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Magistrsko delo obravnava zasnovo algoritma vodenja prožnosti odjema in proizvodnje v distribucijskih omrežjih. Potreba po takšen algoritmu vodenja izhaja iz naslova vedno večjega priključevanja novih tipov naprav, kot so električna vozila, toplotne črpalke ali sončne elektrarne, ki s svojim obnašanjem sodobna distribucijska omrežja postavljajo pred velike izzive na področju obratovanja. K tem izzivom lahko pristopimo na dva načina. Prvi način predstavlja tradicionalni načrtovalski pristop, ki ne upošteva prožnosti, ki jih lahko nudijo novi tipi naprav in odjemalci. Načrtovalci omrežij se tu poslužujejo predvsem nadgradnje omrežij z ojačitvijo obstoječih elementov, kar vodi v neizkoriščenost novo vgrajenih elementov. Alternativo lahko predstavlja upoštevanje potenciala prožnosti odjema in proizvodnje, ki tradicionalno pasivne odjemalce postavi v vlogo aktivnih uporabnikov, ki lahko s svojim prilagajanjem odjema ali proizvodnje pozitivno vplivajo na razmere v omrežju. Cilj magistrskega dela je zasnova algoritma, ki upošteva potencial prožnosti odjema in proizvodnje pri samem obratovanju distribucijskega omrežja. V prvem delu naloge so na kratko predstavljene lastnosti in značilnosti nizkonapetostnih distribucijskih omrežij in njihove obratovalne omejitve. Podrobneje so opisane napetostne in termične omejitve omrežja ter izgube, ki se pojavljajo med obratovanjem distribucijskih omrežij. Te omejitve predstavljajo osnovo pri izračunu priključne zmogljivosti distribucijskega omrežja. V nadaljevanju naloge je predstavljen koncept priključne zmogljivosti distribucijskega omrežja, ki se je do sedaj uporabljal predvsem med načrtovanjem distribucijskega omrežja. Za izračun priključne zmogljivosti lahko uporabimo več vrst metod, med katere sodijo deterministične, stohastične in optimizacijske metode, katerih prednosti in slabosti so predstavljene v priču-jočem delu. Sledi predstavitev obeh metod, ki sta bili preizkušeni znotraj magistrskega dela. Kot potencialno metodo za zasnovo algoritma vodenja prožnosti odjema in proizvodnje smo prepoznali metodo optimizacije z rojem delcev, ki spada med optimizacijske metode, in metodo z občutljivostnimi koeficienti, ki se je do sedaj uporabljala predvsem za regulacijo napetosti na visokonapetostnem nivoju. V zadnjem delu magistrske naloge sta metodi preizkušeni na realnem nizkonapetostnem distribucijskem omrežju znotraj simulacijskega okolja. V prvem delu preizkusa metodi uporabimo za razbremenjevanje omrežja, da bo omrežje zopet obratovalo znotraj postavljenih obratovalnih kriterijev. Simulacijski rezultati prikazujejo, da rezultati obeh metod uspešno zagotovijo, da bo obravnavano omrežje zopet obratovalo znotraj obratovalnih kriterijev. V drugem delu preizkusa smo z metodo, ki temelji na občutljivostnih koeficientih, poizkušali določiti vozliščno priključno zmogljivost, ki bi jo agregator lahko izkoristil za nudenje sistemskih storitev. The master's thesis deals with the design of a flexibility control algorithm for demand and production in distribution networks. The need for such a control algorithm arises from the increasing connection of new types of devices, such as electric vehicles, heat pumps, or solar power plants, which pose great challenges to the operation of modern distribution networks. There are two approaches to addressing these challenges. The first approach is the traditional approach that does not consider the flexibility that new types of devices can provide. Network planners mainly upgrade grids by replacing existing elements, which leads to the underutilization of newly installed elements. An alternative approach could be to consider the flexibility potential of newly connected devices, which puts traditionally passive consumers in the role of active users or prosumers who can positively influence network conditions by adjusting their consumption or production. The goal of the master's thesis is the design of an algorithm that takes into account the potential of demand and production flexibility in the operation of the distribution network. The first part of the thesis briefly describes the characteristics and features of low-voltage distribution networks and their operating limitations. Voltage and thermal limitations of the network, as well as losses that occur during the operation of distribution networks, are described in detail. These limitations form the basis for calculating the hosting capacity of the distribution network. Then, the concept of the hosting capacity of the distribution network, which has so far been used in the planning of the distribution network, is described. Several types of methods can be used to calculate the hosting capacity, including deterministic, stochastic, and optimization methods, whose advantages and disadvantages are presented in this work. The following section introduces both methods that were tested within the master's thesis. As potential methods for designing the flexibility control algorithm, the particle swarm optimization method, which belongs to optimization methods, and the method based on sensitivity theory, which has been mainly used for voltage regulation at the high voltage level, were identified. In the final part of the master's thesis, both methods are tested on a real low-voltage distribution network within a simulation environment. In the first part of the test, the methods are used to ensure, that the network operates within established operational criteria. Simulation results show that the results of both methods successfully ensure that the considered network operates within the established criteria. In the second part of the test, we used the sensitivity coefficient-based method to determine the nodal capacity that an aggregator could utilize to provide system services.

V doktorskem delu obravnavamo zvišanje spoznavnosti v elektroenergetskem omrežju, in sicer se osredotočamo na spoznavnost v srednjenapetostnih in nizkonapetostnih distribucijskih omrežjih. Omenjeno postaja aktualno s potrebo po zvišanju vodljivosti sodobnega distribucijskega sistema z vse višjim deležem obnovljivih virov, toplotnih črpalk, električnih vozil in električnih shranjevalnikov. Po drugi strani zvišanje spoznavnosti predstavlja izziv v današnjih distribucijskih omrežjih, za katere je značilna nizka količina razpoložljivih omrežnih meritev. V začetnih poglavjih naloge so predstavljene ključne značilnosti današnjih elektroenergetskih omrežij. Pri opisu se osredotočamo na lastnosti obeh nivojev distribucije. Vključevanje sodobnih tipov bremen v distribucijska omrežja zahteva vpeljavo vodljivosti v distribucijski sistem. Predpogoj zanjo pa je vzpostavitev spoznavnosti, ki je že dalj časa stalnica v prenosnih omrežjih. Parametri distribucijskih omrežij se bistveno razlikujejo od tistih, ki veljajo za prenosna omrežja, zato neposredna uporaba različnih rešitev, razvitih za prenosno omrežje, ni možna. Je pa omenjeno mogoče nasloviti z namenskim algoritmom za oceno stanja distribucijskega sistema. Dosedanje aktivnosti na področju ocene stanja v distribuciji so predstavljene ob koncu prvega poglavja. Ločeno poglavje obravnava matematično ozadje ključnih gradnikov ocenjevalnika stanja. Ker predstavljajo osnovo metode, je njihovo poznavanje pomembno za razumevanje delovanja samega algoritma. Predstavljeno je ozadje matematičnega modeliranja, ki se zaradi lastnosti distribucijskih omrežij nekoliko razlikuje od modeliranja prenosnega omrežja. Razloženo je tudi ozadje ključnih matematičnih funkcij, s pomočjo katerih ocenjevalni algoritem sistemske meritve prek poznavanja topologije povezuje s spremenljivkami stanja. Uvodni del se zaključuje s predstavitvijo metode uteženih najmanjših kvadratov, ki je najpogosteje uporabljena v ocenjevalniku stanja in tako predstavlja referenco za razviti novi algoritem. Temu sledi opis metode Kalmanovega filtra, ki predstavlja osnovo novega algoritma ocenjevalnika stanja. V sklopu doktorskega dela je bil razvit in praktično preizkušen nov algoritem ocenjevalnika stanja za distribucijska omrežja, ki je predstavljen v nadaljevanju. Ločeno je v podpoglavju podrobno predstavljen zajem in obdelava meritev algoritma. Neposredna uporaba omrežnih meritev namreč ne zadošča, saj je njihovo število v distribucijskem omrežju prenizko za ustrezen nivo redundance. Sledi opis načina priprave matematičnega modela, potrebnega za izvedbo procesa ocene stanja. Med izračunom algoritem ocene stanja pridobljene meritve aplicira na matematični model omrežja in s tem na nek način preverja njihovo smiselnost. To je mogoče samo z ustrezno definiranim omrežnim modelom. Sledi predstavitev nadgradenj, ki smo jih razviti in testirali v sklopu doktorskega dela. Prva predstavlja poenostavitev klasične metode uteženih najmanjših kvadratov za hitrejšo izvedbo ocene stanja nizkonapetostnega distribucijskega sistema. Pri poenostavitvi smo izhajali iz razklopljene metode, ki v primeru prenosnega sistema izkorišča njegove specifične lastnosti pri zanemaritvi posameznih delov sistemskih matrik. Ob upoštevanju razlik med obema napetostnima nivojema smo metodo preoblikovali in uspešno testno izvedli v simulacijski analizi ocene stanja nizkonapetostnega omrežja. Uporabljene predpostavke veljajo samo za nizkonapetostni nivo, torej metode ni mogoče neposredno aplicirati v srednji napetosti. Dodatno imajo ocenjevalniki, osnovani na metodi uteženih najmanjših kvadratov, težavo z robustnostjo v primeru izpadlih meritev, kar je pogost pojav pri merilnih sistemih v današnjih distribucijskih omrežjih. Zaradi opaženih težav z zanesljivostjo merilnega sistema smo se v nadaljevanju osredotočili na robustnejše metode. Mednje sodijo metode iz skupine Kalmanovih filtrov. Nov algoritem smo osnovali na metodi razširjenega Kalmanovega filtra, ki smo jo dodatno nadgradili. Med analizo se je namreč izkazalo, da je mogoče izračun stanja v stacionarnem sistemu bistveno pohitriti s poenostavitvijo na nivoju izračuna sistemskih matrik. Pohitritev ima zanemarljiv vpliv na natančnost izračuna. Z dodatno ustrezno izvedeno detekcijo spremembe v sistemu tako pridemo do hitrega, robustnega in hkrati natančnega algoritma za oceno stanja distribucijskega omrežja. Slednji je bil razvit in implementiran tudi v okviru pričujočega doktorskega dela. V zadnjem delu naloge so ločeno predstavljeni rezultati uporabe razvite metode v laboratorijskem okolju in v realnih omrežjih na terenu. Dodatno je predstavljen način modeliranja samega omrežja. Testiranje v laboratoriju je pokazalo, da razviti algoritem ustrezno zaznava in premaguje izzive, ki so pričakovani v procesu ocene stanja distribucijskih omrežij. Omenjeno se je kot resnično izkazalo tudi med praktično izvedbo, kar je prikazano v zaključnem delu poglavja. To prikazuje tudi izzive, ki so se med praktično izvedbo pokazali v procesu analize podatkovnih baz operaterjev in zajema meritev. Te izzive je bilo treba nasloviti pred samo izvedbo algoritma v realnih omrežjih. Sklepni del podaja zaključke in povzema nekaj glavnih ugotovitev doktorskega dela. Izpostavljeni sta tudi bistveni pomanjkljivosti današnjih distribucijskih omrežij v luči spoznavnosti sistema. Ti sta nezanesljiv merilni sistem in pomanjkljive podatkovne baze omrežij. With the increased penetration of the advanced modern loads, such as distributed renewable energy resources, heat pumps, electric vehicle chargers and energy storage, there is an urge to implement some extent of controllability in the distribution network. This would allow for the better use of existing resources, postponing the need for equipment upgrade. In order to introduce any kind of control to the system, it must be observable in the first place. Establishing observability is a challenge in today's distribution networks, which are known for their low quantity of available network measurements. In the following doctoral thesis, we consider the increase of observability in the power network, with special interest to the medium-voltage and low-voltage distribution networks. Key features of nowadays power networks are presented in the beginning of the thesis. Due to its context, here we focus mostly to the characteristics of the medium and low voltage distribution networks and their key differences in comparison with the high voltage transmission networks. The latter are long known for a successful implementation of different methods that render them observable. With the increasing penetration of modern loads, similar task is now foreseen also for the distribution networks. Due to the significant discrepancy between the two, direct implementation of methods, used in transmission system observability is not possible in the distribution networks. This challenge can be addressed with a dedicated algorithm to assess the state of the distribution system. Recent efforts in the field of the distribution system state estimation are presented at the end of the first chapter. Next chapter gives the mathematical background of crucial parts of the state estimation algorithm. As these represent the heart of the estimation process, their basic knowledge is of great importance for understanding the operation of the algorithm itself. So, the mathematical modelling of the distribution network is given first. As a result of different topologies an electrical characteristic, obtained model differs significantly, from the transmission network models. Additionally, also the necessary measurement functions are explained in this part of the work. These functions and their derivatives enable the estimation algorithm to relate the system measurements with the appropriate state variables, taking into account the mathematical model of the network. The introductory part concludes with a presentation of the weighted least squares method, which is commonly used in the state estimation algorithms. Consequently, it is chosen as a reference for assessment of the developed new algorithm performance. Description of the Kalman filter method is provided next. Kalman filter represents the basis for the developed new state estimation algorithm. A new state estimation algorithm was developed under the scope of the doctoral thesis. Its performance was demonstrated also through field testing in the autonomous estimation of the real Slovenian distribution networks. New algorithm is described in the dedicated chapter. There, the underlying tasks of measurement acquisition and mathematical model development are explained in detail. The straightforward usage of solely network measurements is not sufficient in the distribution network state estimation, as their number is not adequate for establishing the appropriate level of measurement redundancy. Mathematical model, being the other key input of the state estimator, should also be prepared in order to faithfully mimic the real network in order to calculate accurate estimate of the network state. In the process of state estimation, the algorithm attaches the obtained measurements to the mathematical model of the network and thus, in some way, checks their accuracy. This is only possible with a properly defined network model. The presentation of the upgrades, developed and tested as part of the doctoral thesis, are given in the end of the chapter. Firstly, the simplification of the classical weighted least squares method is presented. It enables a faster calculation of the state estimation in the low-voltage distribution system. Simplification is based on the decoupling, known from the transmission system. It takes advantage of some key characteristics of the grid, which allow neglection of the individual parts of the system matrices. Taking into account the differences between the two voltage levels, we redesigned the method and proved its successful performance in the low-voltage network state estimation. However, the employed assumptions are true only in the low voltage network, so the method cannot be applied directly to the medium voltage level. Additionally, estimators based on the weighted least squares method have a problem with robustness in case of great measurement errors, which tend to happen frequently in today’s distribution networks measurement systems. The initial investigations of the established measurement system revealed frequent measurement drops. Consequently, we had to focus ourselves to more robust methods for state estimator. Extended Kalman filter belongs to such methods and was therefore chosen as a basis for the developed new algorithm. During the initial studies it turned out that the state estimation process can be significantly accelerated with introduction of some simplifications to the calculation of system matrices. These can be kept constant when there is no significant change in the estimated system. With additional successful implementation of the system change detection we get to a fast, robust and at the same time accurate algorithm for distribution network state estimation, which is the main outcome of the presented doctoral thesis. In the end, the results of the developed method implementation are presented. This part includes results of the laboratory testing, followed by the results from the real network field testing. Laboratory testing has proven that the developed algorithm adequately detects and overcomes the challenges, expected to emerge in the actual process of distribution network state estimation. This was further on proven through the developed estimator field test and operation. Its brief outcomes conclude the last chapter, together with the difficulties faced during the development and practical implementation of the estimator in the field. These obstacles had to be properly addressed and mitigated prior the algorithm implementation. The final part gives conclusions and summarizes some of the main outcomes of the work. The significant shortcomings of today's distribution networks in the light of system observability are also highlighted. These can be packed to unreliable measurement system and outdated, scarce network databases.

Cilj diplomske naloge je bil izdelati projekt, v katerem je predvidena zamenjava celotne opreme v transformatorski postaji. Predstavljeni so problemi, s katerimi se projektant sreča med izdelavo projekta, kaj vse je treba upoštevati pri projektiranju, ter razlogi za menjavo transformatorja in opreme v transformatorski postaji. Transformatorska postaja je sestavljena iz treh glavnih komponent: iz nizkonapetostne razdelilne stikalne omare, srednjenapetostne razdelilne stikalne omare ter transformatorja. Ker je za učinkovito in zanesljivo distribucijo električne energije do porabnikov potrebna zanesljiva oprema v transformatorskih postajah, jo je treba v določenih časovnih okvirih zamenjati z novo. Življenjska doba distribucijskih transformatorjev je približno 40 let. Stikalne omare se običajno zamenjajo, ko te več ne zagotavljajo varnih in zanesljivih stikalnih manipulacij. V tej diplomski nalogi je predvidena zamenjava starega transformatorja z novim distribucijskim transformatorjem tipa 7HTlM, moči 400 kVA, proizvajalca Kolektor Etra. Za vgradnjo novega srednjenapetostnega stikalnega bloka je predviden Siemensov tipa 8DJH, polnjen s plinom SF6. Nizkonapetostni stikalni blok pa bo izdelalo podjetje IMP TEN in bo narejen po naročilu, v skladu z izračuni ter potrebami transformatorske postaje. V diplomski nalogi je opisan postopek menjave opreme v transformatorski postaji. Predstavljena je vsa oprema, predvidena za vgradnjo. Na podlagi izračunov, predstavljenih v zaključnem delu, so bile izbrane vse potrebne komponente, ki se bodo vgradile v transformatorsko postajo. The main goal of the diploma thesis was to create a project in which, the replacement of all equipment in the transformer station is planned. In the diploma are presented all the problems that a designer may encounter during the production of the project. It also presents what needs to be taken into account when designing and the reasons for replacing the transformer. The transformer station consists of three main components: a low-voltage distribution switch cabinet, a medium-voltage distribution cabinet and a transformer. Since we need reliable equipment in transformer stations for efficient and reliable distribution of electricity to customers, the equipment must be replaced with new equipment within certain time frames. The service life of a distribution transformer is about 40 years. Switch cabinets are usually replaced when they no longer provide safe and reliable switch manipulations. This diploma thesis plans the replacement of the old transformer with a new Kolektor Etra distribution transformer type 7HTIM with a power range of 400 kVA. For the installation of new medium-voltage switchgear, a Siemens switchgear type 8DJH filled with SF6 gas is planned. The low-voltage switchgear will be manufactured by IMP-TEN Company and will be made to order in according to the calculations and needs of the transformer station.

Distribucijska podjetja bodo predstavljala pomembno vlogo pri razvoju distribucijskega omrežja, saj bo zanesljivost in kakovost električne energije predstavljala pomemben del pri doseganju evropskih in slovenskih ciljev glede podnebno nevtralne družbe. Za tako hiter razvoj tehnologij in posledično povečano povpraševanje po električni energiji bo potrebno sorazmerno hitro prilagajanje, razvoj, širitev in nadgradnja obstoječega srednjenapetostnega omrežja in predvsem nizkonapetostnega omrežja, pri čemer se bo manifestirala množična elektrifikacija prometa in ogrevanja. Diplomska naloga je sestavljena iz prvega dela, v katerem govorimo o nacionalnih načrtih za prihodnost, ki so v skladu z evropsko energetsko in podnebno politiko o razogljičenju družbe in doseganju podnebno nevtralne družbe. Nacionalni energetski podnebni načrt je predstavljen skozi pet razsežnosti energetske unije. Pod prvi del pa spada tudi predstavitev nacionalnega standarda SIST EN 50160, ki podaja mejne vrednosti parametrov napetosti na mestu odjema. V srednjem delu govorimo o sestavi distribucijskega načrta in bolj podrobnem pregledu nizkonapetostnega omrežja. Poleg tega zajema še postopek pridobitve koničnih moči gospodinjskih odjemalcev na področju distribucijske enote Trbovlje, ki smo jih uporabili za namen diplomske naloge – tj. pregled stanja na nizkonapetostnem omrežju z usmeritvami za prihodnost. Sledi drugi, analitični del diplomske naloge, v katerem so predstavljeni problematika padcev napetosti v omrežju in način ter namen izračuna padcev napetosti, katerega rezultati se odražajo v stanju na nizkonapetostnem omrežju DE Trbovlje. Poleg dejanskega stanja pa je še predstavljeno predvideno stanje NN omrežja glede množične elektrifikacije prometa in ogrevanja. Narejeni so izračuni, v kakšnem stanju bo omrežje do leta 2030, ko bo potrebno vgraditi nove toplotne črpalke v gospodinjstva in uvesti električna osebnih vozila v gospodinjstva z namenom, da bi dosegli zastavljene nacionalne cilje. Na koncu so predstavljene možne rešitve, ki se jih bodo posluževala distribucijska podjetja za reševanje problematike padcev napetosti zaradi hitrega prehoda v podnebno nevtralno družbo. Zadnji del pa predstavlja pregled stanja in predvidene finančne stroške, ki bi pestili distribucijska podjetja (tukaj govorimo predvsem o stroških distribucijske enote Trbovlje) zaradi nacionalnih načrtov, ki bi se jim morala hitro prilagajati tako distribucijska podjetja kot tudi odjemalci sami. Distributive companies will represent an important role in development of the distributive network, because reliability and quality of electric energy will represent an important role in achieving European as well as Slovenian goals regarding a climate-neutral society. Such rapid development of technologies and consequently increasing demand for electric energy will require a relatively quick adaptation of development, as well as expansion and upgrading of the already existing medium and low voltage network, where mass transport electrification and heating will manifest. This diploma consists of two parts. The first part is about future national plans, which are in conformity with European energetic and climate policy, dealing with decarbonization of society and achieving climate - neutral society. The national energy climate plan is presented through five dimensions of energy union. The first part also deals with SIST EN 50160 national standard presentation, which gives the values of voltage parameters at the place of consumption. The middle part deals with composition of distributive plan and more detailed overview of the low voltage network. In addition, it includes the process of achieving peak powers of household consumers in the area of Trbovlje distribution unit, which we used for the purpose of the diploma thesis. It gives an overview of the low voltage network state, with future directions. The second part, analytical part of my diploma, introduces issues of voltage drops in the network, as well as the way and the purpose of calculating voltage declines which results reflect in the state/condition in low voltage network of DE Trbovlje. Besides the actual state, the projected state of low voltage network, regarding mass traffic electrification and heating is presented. Calculations of what network condition will be by 2030 are made. By the time, it will be necessary to install new heat pumps into households and introduce electric vehicles in order to achieve the already set national goals. Possible solutions, used by distributive companies, to deal with problems of voltage declines, due to the rapid transition to a climate – neutral society, are also presented. The last part presents an overview of the state and estimates financial costs, which could threaten distributive companies (we are mainly dealing with the costs of the Trbovlje distribution unit), due to national plans, which both, distributive companies and customers would quickly need to adapt.

Namen diplomske naloge je s pomočjo najnovejše literature, raziskav in računskih analiz predstaviti situacijo na področju električnih vozil ter omrežne infrastrukture. Pri uvajanju električnih vozil lahko posledično prihaja do preobremenjevanja omrežja. Da bi pridobili celostno sliko, smo v nalogi predstavili vpliv modernizacije z električnimi vozili na elektroenergetski sistem. Glavni cilj diplomske naloge je prikazati, kolikšen vpliv imajo električna vozila na elektroenergetski sistem, vpliv njihove vključitve na okolje in tudi kako zmanjšati preobremenitve sistema. The purpose of the thesis was to identify the situations of electric vehicles and network infrastructure through the acquired literature, researches and analyzes. In this context, the forefront of the thesis was a possibility of introducing electric vehicles and consequently overloading network. In order to gain an overall picture, the thesis was describing the influence of modernization with electric vehicles on the electric power system. The main goal was to demonstrate the impact of electric vehicles on the electric power system, the impact of their integration on the environment, and how to reduce system overload.

V magistrski nalogi je predstavljeno obstoječe razdeljevalno omrežje. Opisana je priprava modelov elementov omrežja, vodov, transformatorjev, bremen in proizvodnih enot, ki so uporabljeni pri simulaciji omrežja. Ustreznost sestavljenega modela omrežja je potrjena z meritvami v omrežju. Cilj naloge je ugotoviti, kakšne vplive ima delovanje polnilne postaje na razdeljevalno omrežje. Preverjeno je delovanje omrežja z vključeno polnilno postajo in brez nje. Primerjana sta napetostna profila omrežja z vključeno polnilno postajo in brez nje. Preverjena je tokovna obremenitev vodov glede na maksimalni dovoljeni tok vodnikov. Predstavljene so standardne rešitve in novejši koncepti, s katerimi je mogoče vplivati na obratovanje omrežja. The master's thesis deals with an existing distribution network. The models of power system elements, like power lines, transformers, loads and power generation units, applied in the distribution system simulation, are presented. The distribution system model obtained in this way is confirmed through the comparison of measured and calculated results. The goal of this thesis is to find out what impacts has charging station on distribution network. The network operation is checked with and without the charging station included. The comparison of voltage profiles in a distribution network operating with and without charging station is performed. The current load of individual lines is checked, considering the maximum allowed current. Standard solutions and newer concepts, that can be applied to influence network operation, are presented and discussed.

V diplomskem delu smo se osredotočili na analizo nekaterih značilnosti distribucijskega omrežja slovenskega trgovca z modnimi izdelki in na izgradnjo ter optimizacijo modela njegovega distribucijskega omrežja. Zaradi zapletenosti procesa pridobivanja podatkov in kompleksne kvantitativne optimizacijske metodologije smo se osredotočili na zgolj 9 vozlišč distribucijskega omrežja, ki sicer dobro predstavljajo značilnosti in karakteristike omrežja ter omogočajo vpogled v delovanje podjetja, ki se ukvarja s prodajo modnih izdelkov, za izvajanje transportnih storitev pa najema zunanje izvajalce. V diplomskem delu smo do potankosti predstavili kvantitativno metodologijo, ki smo jo uporabili za izgradnjo optimizacijskega modela distribucijskega omrežja, prav tako pa smo transparentno predstavili način pridobivanja podatkov, ki smo jih pridobili z zgrajenega modela distribucijskega omrežja v geografskem informacijskem sistemu, s strani slovenskega trgovca z modnimi izdelki in s strani mednarodnega logističnega in transportnega podjetja. Na podlagi pridobljenih podatkov smo lahko do potankosti analizirali značilnosti distribucijskega omrežja, izgradili kvantitativni model in ga optimizirali s pomočjo Excelovega Reševalnika, na koncu pa tudi predstavili optimalne rešitve oz. organizacijske verzije enostavnega in kombiniranega modela distribucijskega omrežja. Najpomembnejša ugotovitev diplomskega dela je, da obstajajo pomembne razlike med karakteristikami stroškovnih podatkov, če so ti podani s strani transportnega podjetja, ali pa so podani s strani podjetja, ki za transport najema zunanje izvajalce. Ko so podatki podani s strani transportnega podjetja, vedno obstaja močna korelacija med transportno razdaljo in stroški transporta, medtem ko te korelacije pri podatkih slovenskega trgovca z modnimi izdelki praktično ni. To se pokaže tudi v optimalnih rešitvah modela distribucijskega omrežja, ugotovitev pa nasprotuje dosedanjim rezultatom preteklih raziskav in s tem odpira nove možnosti za nadaljnje raziskave. In the bachelor thesis, we focused on the analysis of some characteristics of the distribution network of Slovenian fashion retailer, and on defining, building, and optimization of the distribution network model. Due to the complexity of the data collection process, and complex quantitative optimization methodology, we only focused on 9 distribution nodes, which adequately represent characteristics of the distribution network, and provide an interesting insight into the company, which outsources transportation to 3PL providers. In the thesis, we thoroughly presented the quantitative methodology, which is used for building of the optimization model, and we also transparently presented the data collection process, since we collected the data from the model, which was built in the geographical information system, from Slovenian fashion retailer, and from the international logistics and transportation company. On the basis of the collected data, we were able to scrutinize distribution network characteristics, build quantitative model and optimize it with the use of Excel`s Solver, and present the optimal solutions or organizational versions of the simple models (1 cost aspect) and mixed models (2 different cost aspects) of the distribution network. The most important discovery of the bachelor thesis is the fact that there are major differences in the characteristics of the data, when they are provided by a transportation (trucking) company or when they are provided by a company, which outsources its transportation to 3PL providers. In the first case (international logistics and transportation company), there is always a strong correlation between transportation distance and transportation costs (in terms of money), whereas in the other case (Slovenian fashion retailer) there is practically no correlation between the two. This is also clearly visible in the optimal solutions of the distribution network model, and the outcome strongly contradicts the results of the previous researches covering this scientific area, and thus provides the incentive and guidelines for further research work.

V bližnji prihodnosti bodo električna vozila nedvomno zamenjala vozila na fosilni pogon. Pri vseh vprašanjih in razlagah o električnih vozilih in njihovem hitremu razvoju se nam porodi najbolj pomembno vprašanje: kako bi množična uporaba električnih vozil vplivala na distribucijsko omrežje, o katerem ni veliko govora, vendar brez odgovora na to vprašanje ne bo mogoče nadaljevati z razvojem elektromobilnosti, saj imajo lahko napačne analize pri takem vprašanju katastrofalne posledice – govorimo lahko o razpadu omrežja. Ker obstoječa energetska omrežja učinkovito in zanesljivo delujejo že približno sto let, želimo, da tako tudi ostane. Zato se tu soočimo z analizo, ki vključuje nove trende oz. nove izzive na tem področju. Tu govorimo o električnih avtomobilih, ki prinašajo naraščanje porabe energije, ne samo povečanje koničnih moči, temveč tudi nove konične obremenitve (predvsem ponoči zaradi cenejše energije). Te se vključujejo že v obstoječo problematiko, kot so okoljska problematika, razpršena proizvodnja, prostorske omejitve in težave z umeščanjem v prostor ter trenutno tudi zelo problematična – starajoča se infrastruktura. Za ugotovitev, da trenutni elektroenergetski sistem (vsaj NN) ni pripravljen na takšen skok porabe električne energije, ki ga prinaša elektromobilnost, ni potrebna izčrpna analiza, saj vemo, da se distribucijska podjetja s preobremenjenostjo omrežja in transformatorji premajhnih moči srečujejo že zdaj v sodobnem sistemu. Kot bomo videli, napoved, da trenutni elektroenergetski sistem z obstoječimi koncepti načrtovanja ni pripravljen na učinkovito vključevanje novih porabnikov oz. elementov, ni napačna. Menimo, da bodo morala distribucijska podjetja tej problematiki posvetiti še veliko pozornosti, saj je razvoj elektromobilnosti, še posebej v zadnjih letih, ekstremen. To bi lahko pomenilo, da nepripravljenost na nove trende privede do kolapsa omrežja. K sreči se razvoj takih trendov ne zgodi čez noč, kar pomeni, da se elektroenergetski sistem lahko počasi in postopoma nadgrajuje – lahko bi rekli, da je to nekakšna finančna razbremenitev. Če se to ne bo zgodilo (sprotno vlaganje v sistem), bi stanje privedlo do prevelikih finančnih obremenitev, kar v najboljšem primeru pomeni počasnejši razvoj na področju energetike v Sloveniji. Vsem tem negativnim scenarijem se lahko izognemo z dobro organizacijo in s pametnim programom. V programu razvoja pametnih omrežij v Sloveniji je napisan celoten načrt nadgradnje današnjega koncepta obratovanja in načrtovanja sistema in v celoto učinkovito vključuje tudi nove elemente, kot so npr. odjemalci z možnostjo prilagajanja porabe, električni avtomobili, hranilniki električne energije itd. In the near future, electric vehicles will undoubtedly replace fossil fuel vehicles. Among all the questions and explanations, considering electric vehicles and the rapid development of them, the most important is how can massive usage of electric vehicles affect the distribution network, which is not much discussed, but without answering this question it will not be possible to continue the development of electromobility. The consequences of an incorrect analysis of such a problem may have a catastrophic effect – we are talking about the collapse of the network. Existing energy networks have been operating efficiently and reliably for about a hundred years, and we want it to remain so. That is why we are faced with an analysis that includes new trends and new challenges in this area. We are reffering to electric cars that bring an increase in energy consumption, not just an increase in peak power but also a new peak load (especially at night due to cheaper energy). These are included in the already existing issues, such as environmental issues, dispersed production, spatial constraints and space placement problems, and currently also very problematic – older, aging infrastructure. There is no need for any careful analysis in order to find out that the electricity system (at least low voltage) is not prepared for such a leap in electricity consumption caused by electromobility, as we know that distribution companies are already facing overload networks and transformers with little power in the modern energy system. As we will see, the announcement that the current power system with the existing concepts of planning is not ready to effectively integrate new consumers or elements, is not incorrect. We believe that distribution companies will have to pay a lot of attention to this problem, because the development of electromobility, especially in recent years, is extremely high. This could mean that unwillingness to new trends leads to a collapse of the network fortunately, such trends do not develop overnight, which means that the power system can be slowly and gradually upgraded – it could be said to be a kind of financial relief. If this does not happen, the situation would lead to excessive financial burdens and a slower development in the field of energy in Slovenia. These negative scenarios can be avoided by a good organization and a good programme. The entire plan of upgrading the present concept of operation and system design is written in the programme of smart grid development in Slovenia, where it effectively, as a whole, integrates new elements, such as consumers with the ability to adjust consumption, electric cars, power savers, etc.

Zaradi vse večje onesnaženosti zraka in vedno večje potrebe človeka po električni energiji bo v omrežje vključenih čedalje več razpršenih virov. Ti razpršeni viri nam povzročajo spreminjanje smeri pretoka energije. Cilj je ugotoviti kako ti razpršeni viri in veliki porabniki vplivajo na napetostni profil. High air pollution and an increasing need of mankind for electric power increases the share of renewable energy based distributed generation units in electricity distribution networks. These generation units can change the direction of energy flow in the networks several times per day. The aim is to find out how the distributed generation units and large loads influence the voltage profile.

Namen diplomske naloge je predstaviti koncep tvirtualne elektrarne in njen vpliv na obratovanje srednjenapetostnega elektroenergetskega omrežja. V pametnih omrežjih virtualna elektrarna predstavlja del pametnega omrežja, ki je odgovor na spremenjene razmere v omrežju zaradi novonastalih elementov. So posledica sprejetja zavez glede deleža obnovljivih virov v porabi energije, zmanjševanja izpustov CO2 in povečanja energetske učinkovitosti ter razvoju nove tehnologije. V diplomski nalogi predstavljamo rešitev za vzpostavljanje stabilnosti SN omrežja ob izpadu oziroma upadu električne energije. V izbranem omrežju mnogokrat prihaja do izpadov električne energije, zato smo si izbrali vir energije z močjo 1 MVA, v našem primeru dieselski agregat. Priključimo ga na distribucijsko omrežje ob izpadu ali padcu napetosti. Osredotočili smo se na delovanje virtualne elektrarne, predstavili postopek priključitve in dokumentacijo, ki je potrebna, da lahko uporabimo virtualno elektrarno. Kot del, v katerem smo preučili in naredili analizo uporabljenega izvoda, smo preračunali padce napetosti ter obremenitve oziroma pretoke moči na distribucijskem omrežju. V zaključku oziroma kot rešitev opazimo, da je vpliv generatorja na izbran sistem pri različnih obremenitvah (50 % in 100 %) opazen, saj se znižajo padci napetosti. V primeru delovanja je opažen padec delovne moči in stabilizacija napetosti tako v razdelilni transformatorski postaji kot tudi na opazovanem srednjenapetostnem izvodu. Pri polni in polovični obremenitvi srednjenapetostnega izvoda je 30 % znižanje obremenitve celice v razdelilni transformatorski postaji. Vpliv generatorja se kaže tudi pri izgubah, ki so prisotne v srednjenapetostnem izvodu. Izgube se skoraj prepolovijo, vzrok zmanjšanja izgub pa tiči v manjših pretokih moči po omrežju. Vsi ti izračuni so pri najboljših pogojih, ne vemo pa, kako bi se to odražalo v realnosti. The purpose of our thesis is to introduce the concept of virtual power plants and their energy impact on medium electricity grid. When speaking of smart grids, a virtual power plant constitutes a part of a smart grid which is in itself a response to a change in conditions, caused by an unpredicted occurrence. Virtual power plants came to being as a consequence of obligations concerning shares of renewable sources in energy consumption, reduction of CO2 emissions, other improvements in energy efficiency and development of new technology . Our thesis presents a solution in case of a blackout or a failure in power supply. In the grid chosen for our research, power cuts occur frequently, which lead us to choose a power source with an output of 1 MVA. In our case, it was a diesel-powered generator. It is connected to the distribution network upon a partial or total failure in power supply. Focussed on operation of virtual power plants, the paper set about installation and documentation necessary to put the power plant in operation. In the analysis part we have calculated the voltage drops and choke points or current within the distribution network. We come to a conclusion that the generator’s energy impact on the chosen electricity system at different loads (50 % and 100 % load) is significant, since voltage drops are decreased. Regarding operation, we noticed output power decrease and voltage stabilization at the transformer stations, as well as the observed medium voltage outlet. At the full and half load on the medium voltage power outlet, a 30 % load decrease of the transformer station cell is noted. Also notable is generator’s influence on power losses at the mv power outlet. The power losses are reduced to half, the reason for this lying in the lower current throughout the grid. These calculations have been conducted in ideal conditions, but it is uncertain, how these calculations would vary in reality.

Zaradi zagotavljanja predpisane kakovosti električne energije vsem odjemalcem, priključenim na razdeljevalno omrežje, je nujno potrebno ugotoviti, kakšen vpliv na odjemalce in razdeljevalno omrežje ima sprejeta Uredba o samooskrbi z električno energijo iz obnovljivih virov energije (Ur. l. RS, št. 97/15). V magistrski nalogi je izvedena analizo stanja neto samooskrbe v Sloveniji. Prikazani so poteki dnevnih diagramov porabe in proizvodnje za različen tip neto samooskrbe z električno energijo iz obnovljivih virov energije, merjene s števcem električne energije in z instrumentom za ugotavljanje kakovosti napetostnih razmer. Na realnem srednjenapetostnem in nizkonapetostnem omrežju je izvedena simulacija napetostnih profilov, za primer stoodstotne neto samooskrbe, na podlagi letnih izmerjenih podatkov. Naštetih je več sistemskih ukrepov za širšo vpeljavo neto samooskrbe, najpomembnejši je možnost zniževanja napetosti z generacijo jalove moči. In order to ensure that all consumers who are connected to a distribution grid are provided the same quality of electricity supply, it is necessary to determine what kind of impact the Decree on self-supply of electricity from the renewable energy sources (Official Gazette of the Republic of Slovenia, No. 97/15) has on the consumer and on the distribution grid. In this Master’s thesis, I examined the current state of net self-sufficient energy supply in Slovenia. Using electricity meters and power quality analysers, I diagrammed the daily production and consumption for different types of net self-sufficient energy supply from renewable energy sources. Based on annual data from the electric utility, I performed a simulation of voltage profiles in a real medium-voltage and low-voltage power grid – in a scenario in which net self-sufficient energy supply is at 100%. I also listed a number of systemic measures that could help increase the level of net self-sufficient energy supply, the most important of them being the possibility of lowering voltage by generating reactive power.

Ena izmed osnovnih nalog elektrodistribucijskih podjetij je zagotavljanje nemotene oskrbe z električno energijo in ustreznih padcev napetosti znotraj predpisanih mej. Neustrezni napetostni profili v nizkonapetostnem omrežju najbolj vplivajo na končne porabnike. V magistrski nalogi je predstavljeno trenutno stanje pri napajanju oddaljenih odjemalcev, ki so napajani z napetostjo 0,95 kV. Za zagotavljanje ustreznih napetostnih razmer so predstavljene in ovrednotene štiri izvedbe napajanja, in sicer napajanje z 0,4 kV, napajanje z 0,95 kV, napajanje z 0,4 kV in napetostnim stabilizatorjem ter napajanje z 0,4 kV in baterijskim sistemom. S pomočjo izdelanih simulacijskih modelov omrežja smo izvedli analizo napetostnih razmer, analizo izgub električne energije in ekonomsko analizo. Na koncu smo posamezne rešitve ovrednotili in medsebojno primerjali. One of the basic tasks of electrical distribution companies is to ensure constant supply of electrical energy and proper voltage conditions in networks within prescribed limits. Inadequate voltage profiles in low voltage networks have the greatest impact on end users. Master's thesis presents current status of power supply for remote users that are powered with 0,95 kV. Provision of appropriate voltage conditions is presented for four different power supply solutions, which are power supply with 0,4 kV, power supply with 0,95 kV, power supply with 0,4 kV with voltage booster and power supply with 0,4 kV with battery system. Based on simulation models of the discussed network, we analysed voltage conditions and electrical energy losses. We also performed economic analysis for each of the four presented solutions. Lastly, we evaluated them and compared them to each other.

Namen diplomske naloge je predstaviti toplotne črpalke in njihov vpliv na kakovost električne napetosti v omrežju. Odjemalci v današnjem času uporabljamo ogromno električnih naprav, kjer mnoge od njih slabšajo napetostne razmere v omrežju. Večkrat je mentor praktičnega izobraževanja v podjetju Elektro Gorenjska, d.d. pri reševanju problemov zaradi slabih napetostnih razmer naletel na odjemalce, ki so kot toplotni vir uporabljali toplotne postaje. Na njegovo priporočilo sem izbral toplotne črpalke, ki so zadnje čase močno v porastu. Na konkretnem primeru sem prikazal napetostno stanje odjemalca, ki za ogrevanje hiše uporablja toplotno postajo in se je zaradi težav s kakovostjo napetosti pritožil distribucijskemu podjetju. S to diplomsko nalogo bi rad poudaril, da za slabe napetostne razmere ni mogoče kazati s prstom le na enega krivca. To je težava, v katero so vključeni tako proizvajalci električnih naprav, odjemalci kot tudi distribucijska podjetja. Slednja so kot dobavitelj električne energije seveda dolžna vzpostaviti ustrezne napetostne razmere, vendar pa so zaradi nevednih in nerazumevajočih odjemalcev večkrat kritizirani kot edini krivec. V začetku diplomskega dela sem na kratko predstavil kakovost oskrbe z električno energijo, ki je temelj za zanesljivo delovanje strojev in za minimaliziranje njihovih izgub, za preprečitev okvare opreme in naprav ter za končno zadovoljstvo uporabnikov. Kakovost oskrbe z električno energijo je nadpomenka kakovosti napetosti v omrežju. Kakovost napetosti sloni na poznavanju kratkostične moči in na elektromagnetni združljivosti, določena pa je s standardom SIST EN 50160. Podvržena je tokovnim in elektromagnetnim motnjam, ki napetost popačijo ter poslabšajo delovanje naprav in opreme. Opisal sem vseh trinajst elektromagnetnih motenj, vendar me v povezavi s toplotnimi črpalkami zanimajo le napetostni upadi in hitre napetostne spremembe. V drugem delu naloge sem se površno dotaknil distribucijskega omrežja, ki je zadnji segment v verigi omrežja, od vira energije do odjemalca. Za zagotavljanje napetosti in frekvence v skladu s standardi mora biti omrežje dobro načrtovano. Velikokrat je ravno neustrezen presek vodnikov kriv za nedopustno velike tokovne obremenitve in za prevelike padce napetosti. Pri načrtovanju so pomembne tudi dolžine vodnikov med uporabniki, oddaljenost med virom in odjemalcem ter faktor istočasnosti. Izpeljal sem tudi enačbo za izračun padca napetosti na vodu z dolžino l. Tretji del diplomske naloge opisuje toplotne črpalke, ki so zadnje čase kot način ogrevanja zelo v porastu. Predstavljajo obnovljivi vir energije, saj črpajo sončno energijo akumulirano v snoveh. Opisal sem splošno delovanje tokokroga toplotnih naprav, njene temeljne enote ter različne vrste glede na princip delovanja. Pri svojem raziskovanju sem se usmeril v toplotne črpalke zrak/voda, kjer se izkorišča toploto akumulirano v zraku in se jo prenese na vodo. Podrobneje sem se posvetil tudi električnim elementom znotraj toplotne črpalke. Kompresor je zanimiv zlasti iz vidika zagonov in njegove glasnosti, električno krmiljenje in regulacija ter električni grelec pa iz vidika povečanja porabe električne energije. V četrtem delu naloge sem poudaril razloge za nastanek težav v relaciji toplotnih črpalk in elektroenergetskega omrežja. Težave toplotnih črpalk nastanejo zaradi preobčutljivosti na elektromagnetne motnje ali morebitnih velikih zagonskih tokov, težave v omrežju pa vzrok starosti ali slabega načrtovanja. V zadnjem delu diplomske naloge sem teoretični del nadgradil s konkretnim primerom slabih napetostnih razmer. Odjemalec uporablja kakovostno toplotno črpalko z mehkim zagonom, vzrok za težave pa se nahaja v omrežju s premajhnimi preseki. The aim of this thesis is to present heat pumps and their impact on the quality of the electricity supply network. Customers today use a lot of electrical appliances, where many of them deteriorating voltage conditions on the network. Several times the mentor of practical education in the company Elektro Gorenjska, d.d. in solving problems due to poor voltage conditions encountered clients who are used as the heat source of the heat station. On his recommendation I chose the heat pump, which recently strongly on the rise. A specific example I show the stress state of the client, which is used for heating houses heat station and is due to problems with the quality of the voltage appealed to the distribution company. This thesis would like to emphasize that the poor power situation can not show the finger at only one culprit. This is a problem which includes both manufacturers of electrical appliances, customers as well as distribution companies. The latter as a supplier of electricity, of course, required to establish the appropriate voltage conditions, but because of the ignorant and unsupportive customers repeatedly criticized as the only culprit. At the beginning of the thesis, I briefly introduced the quality of electricity supply, which is the basis for the reliable operation of the machines and to minimize their losses, to prevent damage to the equipment and appliances, and for end user satisfaction. The quality of the power supply is superior voltage quality in the network. The voltage quality is based on knowledge of the short-circuit power and electromagnetic compatibility and determined by the SIST EN 50160 standard and is subject to the current electromagnetic disturbances that distort the voltage and impair the operation of plant and equipment. I described all thirteen of electromagnetic interference, but I'm in conjunction with heat pumps only interested voltage sags and rapid voltage changes. In the second part of the thesis I carelessly touched the distribution network, which is the last segment in the chain network, the power source to the customer. To ensure voltage and frequency in accordance with the standards must be well-planned network. It is often very inadequate conductor cross section to blame for the unacceptable high current load and excessive voltage drops. When planning are also important as the cable length between the users, the distance between the source and the customers as well as simultaneous factor. I also carried out the equation for calculating the voltage drop on the line with a length l. The third part of the thesis describes a heat pump, which recently as a method of heating is on the rise. A source of renewable energy, as extracting solar energy accumulated in substances. I described the general operation of the circuit thermal plants, its basic unit and different types according to the principle of operation. In my research I have focused on the heat pump air / water, which exploits the heat accumulated in the air and transfer it to the water. More information I dedicated the electric element inside the heat pump. The compressor is particularly interesting from the perspective starts and its volume electric control and regulation, and an electric heater but from the point of view of the increase in electricity consumption. In the fourth part of the thesis I pointed out the reasons for the emergence of problems in between the heat pump and the electricity grid. Problems of heat pumps caused by hypersensitivity to electromagnetic interference or any large initial currents problems in the network but the cause of old age or poor planning. In the last part of the thesis I theoretical part with concrete examples of bad voltage conditions. The client uses good quality heat pump with soft start, the cause of the problem is located in the network with insufficient sections.

V magistrski nalogi je predstavljeno obstoječe razdeljevalno omrežje. Optimizacija njegovega delovanja je izvedena s spreminjanjem konfiguracije in z generiranjem jalove moči. V delu je opisana priprava modelov elementov v omrežju, vodov, transformatorjev, bremen in proizvodnih enot, ki so uporabljeni v optimizaciji. Ustreznost sestavljenega modela je potrjena z meritvami v omrežju. Cilj optimizacije je zagotoviti napajanje industrijskega odjemalca, ki želi povečati moč odjema ob hkratnem zagotavljanju ustreznih napetostnih profilov v obstoječem omrežju. V obravnavanem omrežju obstajajo tudi večje proizvodne enote, ki dvigujejo napetost v posameznih točkah omrežja. Za zagotavljanje ustreznosti napetostnega profila so preverjene možnosti spremembe konfiguracije omrežja, ki obsegajo radialno obratovanje in obratovanje v zanko, preverjena pa je tudi možnost zniževanja napetosti z generacijo jalove moči induktivnega značaja. The master's thesis deals with an existing distribution network. Its operation is optimized through the reconfiguration and reactive power generation. The models of power system elements, like power lines, transformers, loads and power generation units, applied in the distribution system model inside optimization procedure, are presented. The distribution system model obtained in this way is confirmed through the comparison of measured and calculated results. The optimization goal is utilization of existing network infrastructure to supply an industrial costumer with increased load demand, simultaneously providing a proper voltage profile in the network. Larger power generation units in the discussed network increase the voltage profile. To provide a proper voltage profile the network reconfigurations, considering radial as well as operation in the loop, are applied together with the inductive character reactive power generation.

V magistrskem delu je prikazan vpliv generatorja na kratkostične razmere v distribucijskem omrežju. Namen je ugotoviti vpliv sinhronskega generatorja na kratkostične toke, ki so na mestu priključitve izhodiščni podatek za projektiranje in dimenzioniranje posameznih elementov omrežja. Kratkostični tokovi so v točki kratkega stika določeni s pomočjo programskega orodja DMS, ki je razvito za analizo realnih razmer v omrežju in med drugim omogoča tudi izračune parametrov vseh vrst kratkih stikov. Potrditev modela in točnosti izračunanih parametrov kratkega stika s programskim orodjem DMS je izvedena s primerjavo rezultatov programskega orodja z rezultati dejanskih meritev in z rezultati simulacije v programskem paketu Matlab. Analiza vpliva generatorja na kratkostične toke v distribucijskem omrežju je izvedena v točki blizu generatorja in v točki daleč od generatorja. Ugotovljeno povečanje kratkostičnih tokov zaradi vgradnje generatorjev v distribucijsko omrežje je potrebno upoštevati pri projektiranju in dimenzioniranju distribucijskega omrežja. In the master's degree thesis the influence of the generator at short-circuit current within the distribution network is shown. The aim is to determine the impact of synchronous generator on short-circuit currents that are, at the connection point, the starting points for planning and dimensioning of individual elements of the network. Short-circuit currents are determined by a particular software tool DMS at the point of short circuit. It is developed for analysis of the real situations in the network and it also provides the calculations of parameters of all types of short circuits. The confirmation of the model and the accuracy of the calculated parameters of short-circuit with DMS tools is carried out by comparing the results of the DMS software tool with the results of actual measurements and the results of the simulations in Matlab. The analysis of the influence of the generator on short-circuit currents within distribution network is carried out at a point close to the generator and at a point far from the generator. The findings show that the increase in short-circuit currents due to the installation of generators to the distribution network must be taken into account while planning and dimensioning the distribution network.

V sodobnih sistemih vodenja distribucijskih omrežij je ena izmed glavnih funkcij izračun pretokov energije. V tem magistrskem delu je izračun pretokov energije po eni izmed obstoječih metod uporabljen v kombinaciji z optimizacijskim algoritmom na realnem primeru distribucijskega omrežja Zgornje Savinjske doline, natančneje na daljnovodih Rastke in Logarska dolina. Ovrednoten je vpliv električne energije proizvedene iz razpršenih virov na obravnavano omrežje. S postopkom optimizacije so določene referenčne vrednosti za generacijo delovne in jalove moči razpršenih virov, ki so priključeni na nizkonapetostni strani transformatorskih postaj. Pri tem je analiziran vpliv generacije delovne in jalove moči na profil napetosti ter na izgube v obravnavanem srednjenapetostnem omrežju. Preverjena je robustnost in uporabnost predlaganega algoritma za različna obratovalna stanja. The load flow calculation is one of the main functionalities incorporated in modern distribution network management systems. In this master thesis, an already known load flow calculation method, combined with an optimization procedure, is applied and tested in the case of real distribution network in Zgornja Savinska dolina (upper part of valley Savinjska dolina), more precisely on distribution lines Rastke and Logarska dolina. The impact of electrical energy produced in distributed generation units on discussed distribution network is evaluated. The optimization procedure is applied to determine the reference values for active and reactive power generation in distributed generation units connected to the low voltage side of distribution transformers, where the impact of generated active and reactive power on voltage profile and distribution network losses in medium voltage network is analyzed. The robustness and usefulness of the proposed algorithm regarding its suitability to be used in different operating conditions is checked.

Vsak elektroenergetski sistem mora kot osnovni cilj zagotoviti porabnikom električne energije zanesljivo oskrbo s kakovostno električno energijo. Zato je bil ustanovljen standard o kakovosti napetosti v javnih razdelilnih omrežjih - SIST EN 50160. Namen diplomskega dela je bil načrtovanje priključitve in raziskava različnih vplivov na kakovost električne napetosti ob vključitvi sončne elektrarne na razdelilno omrežje. Meritve smo izvajali na odseku, kjer sončna elektrarna ni priključena neposredno v transformatorsko postajo ampak je med priključkom in njo še nekaj odjemalcev električne energije. Prva metoda diplomskega dela je bila izvajanje meritev kakovosti električne napetosti po standardu SIST EN 50160, pred in po priključitvi sončne elektrarne na omrežje z ustreznimi merilniki - FLUKE 1744 Power Quality Logger. Pri drugi metodi smo uporabili programski paket za analizo in načrtovanje razvoja razdeljevalnega omrežja - GREDOS in s pomočjo programa preverili rezultate, ki smo jih pridobili z meritvijo kakovosti električne napetosti. Glavni problemi, na katere smo naleteli, so bili: povišana napetost, neravnotežje napetosti in harmonsko popačenje napetosti. Every power system has as primary goal to provide customers with a reliable quality electricity supply. Therefore a voltage quality standard in public distribution networks established - SIST EN 50160. The purpose of the graduation thesis was the design of a solar power plant connection to the distribution network and study various influences on the quality of electricity supply. Measurements were carried out on a section, where the solar power plant is not directly connected to a transformer station, but on the connection between it and some consumers of electrical energy . The first method of the thesis was measurements of voltage quality standard - SIST EN 50160, with appropriate gauges - FLUKE 1744 Power Quality Logger .In the second method we used a software package for the analysis and design of distribution network development - GREDOS, to check the results, which were obtained by measuring the voltage quality .The main problems that we encountered were: increased voltage, voltage unbalance and harmonic voltage distortion.

Odkrivanje nepooblaščenih odjemov na nizkonapetostnem distribucijskem omrežju predstavlja elektro distribucijskim podjetjem stalne izzive. Tehnološki razvoj in postopno posodabljanje sistema merjenja z izgradnjo naprednega sistema merjenja omogoča nove pristope v hitrejšem in učinkovitejšem odkrivanju nepooblaščenih odjemov. V večini primerov kontrolorji odjema s primerjalnimi analizami izmerjene energije na različnih točkah v omrežju ugotavljajo odstopanja porabe električne energije. Izkušnje pri iskanju nepooblaščenih odjemov kažejo, da bi lahko na osnovi obstoječih merilnih sistemov razvili metodo, ki bi bolj natančno pokazala na storilce nepooblaščenih odjemov, kar je osnovna motivacija diplomskega dela. Diplomska naloga osvetli uporabnost računskih metod za iskanje lokacije nepooblaščenega odjema na osnovi t.i. kazalca napak in t.i. P/U metode. Pričakujemo, da bi predstavljeni metodi zmanjšali čas in obseg iskanja lokacij nepooblaščenih odjemov. Detection of an unauthorised consumption in a low-voltage distribution network represents a great challenge for electricity distribution companies. Technological development and gradual modernization of the measurement system with the installation of an advanced automatic metering system allows new approaches for faster and more effective detection of a theft of electric energy at the end consumers. In most cases the deviation of electricity consumption is determined by comparative analyses of the measured energy at different points in a distribution network. The following thesis explores the effectiveness of the calculation methods based on error indicator and so called P/U method. The described methods have potential to reduce a detection time of a theft and to simplify the locating of the unauthorised consumption.

Diplomska naloga analizira vpliv malih fotovoltaičnih elektrarn na napetostni profil srednjenapetostnega omrežja in izgube, ki nastanejo pri spremenjenem pretoku energije. Na izbranem delu omrežja proučimo obratovanje malih fotovoltaičnih elektrarn, predpise za njihovo obratovanje in načine reguliranja napetosti. In this thesis the effects of small solar power plants on the voltage profile of a distribution network were analysed including the power losses due to changes in power loads. A selected part of network was used to study the performance of solar power plants as well as technical measures concerning their performance and voltage regulation.

Delo obravnava analizo napetostnih razmer in izgub razdeljevalnega omrežja električne energije, v katerega so vključeni razpršeni viri. Pri analizi napetostnih razmer ob vključitvi razpršenih virov je prikazana primerjava med rezultati statičnega (Gredos) in poenostavljenega dinamičnega (Matlab/Simulink) modela razdeljevalnega omrežja. Rezultati kažejo velik razkorak v spremembah napetosti v stacionarnem obratovalnem stanju v primerjavi s prehodnim pojavom spreminjanja moči vira, katerim so različne vrste virov povsem različno podvržene. This diploma thesis deals with the analysis of voltage conditions and losses in an electricity distribution network with distributed generation. The analysis of voltage conditions in the distribution network with distributed generation units is performed by using the program Gredos for steady-state analysis and a simplified dynamic model build in the program package Matlab/Simulink. The results presented in the diploma thesis show a substantial difference between the voltage profiles in steady-state and transient operations caused by changing power of distributed generation units.

Diplomsko delo obravnava vpliv transformatorja z regulacijskim stikalom na obratovanje distribucijskega omrežja. Za ovrednotenje vpliva transformatorja z regulacijskim stikalom je izdelan simulacijski model dela distribucijskega omrežja, v katerega so vključene tudi sončne elektrarne. V modelu omrežja je klasični transformator zamenjan s transformatorjem z regulacijskim stikalom. Izvedeni so simulacijski izračuni na obstoječem nizkonapetostnem omrežju in na omrežju s transformatorjem z regulacijskim stikalom. Izračuni so izvedeni za različna obratovalna stanja proizvodnih virov in odjemalcev električne energije. Izvedena je bila analiza vpliva spreminjanja nastavitev transformatorja z regulacijskim stikalom na napetostni profil omrežja. Rezultati simulacijskih izračunov kažejo, da lahko s transformatorjem z regulacijskim stikalom v veliki meri uravnavamo napetostna odstopanja od standarda SIST EN 50160. The diploma thesis deals with the impact of transformer with tap changer on distribution network operation. To evaluate the impact of the transformer with tap changer on distribution network simulation model with solar power plant is made. In the network model the classic transformer is replaced by transformer with tap changer. Simulations are implemented on the existing network and on the network with transformer with tap changer. The calculations are performed for different operating conditions of solar power plants and loads. The impact of transformer with tap changer on the voltage profile is evaluated. The results of simulations indicate that the transformer with tap changer can help to avoid voltage profile deviations from the standard SIST EN 50160.

Določitev pretokov energije predstavlja temelj sodobnih sistemov vodenja distribucijskih omrežij. Zato moramo zagotoviti zmogljiv algoritem za določitev pretokov energije, ki hitro konvergira, ima minimalno porabo pomnilniškega prostora in predstavlja numerično robustno metodo, prilagodljivo različnim obratovalnim scenarijem. V magistrski nalogi je podan pregled metod za izračun pretokov energije. Prikazan je postopek modeliranja elementov distribucijskega omrežja – vodov, bremen ter razpršenih proizvodnih enot. Pet determinističnih metod za izračun pretokov energije je implementirano in podrobneje analizirano. Ovrednotenje in primerjava obravnavanih metod glede njihove učinkovitosti in primernosti za izračune pretokov moči v srednjenapetostnih in nizkonapetostnih nesimetričnih trifaznih distribucijskih omrežjih je izvedeno na primeru dela distribucijskega omrežja mesta Maribor. Load flow analysis represents one of the core elements in modern control of electricity systems. Therefore, it is necessary to provide efficient, numerically robust load flow algorithm with fast convergence and minimum usage of memory, suitable for variety of operating scenarios. The Master Thesis gives a review of load flow methods as well as the procedure of modeling the distribution network elements – line sections, loads and distributed generation units. Five deterministic methods, amongst presented ones, have been implemented, compared and evaluated on the low voltage part of the three – phase distribution network system. Furthermore, evaluation of implemented methods for load flow calculation of middle voltage networks has been performed on the realistic model of middle voltage part of distribution network in Maribor.

V uvodu nam predstavi osnovne geografske in demografske značilnosti Postojne ter distribucijsko omrežje na področju Občine Postojna in navede ključne podatke o RTP Postojna ter njenem napajanju. Nadaljuje se s prikazom nastanka zimskega dodatnega bremena – predstavi pogoje za tvorjenje dodatnih bremen in predstavi območja v Sloveniji, kjer se žledenje najpogosteje pojavlja. V nadaljevanju sledi kronološki opis žledenja na območju Občine Postojna v začetku leta 2014 in vpliv na EES. Hkrati predstavi tehnične rešitve, ki so bile izvedene v tem času. Sledi obravnava različnih možnosti napajanja RTP Postojna, kjer so opisno in grafično predstavljene možne rešitve. V zaključku avtor oceni svoje delo in poda komentar na predstavljene rešitve. In the introduction, the thesis presents the basic geographic and demographic characteristics of Postojna and the distribution network in the Municipality of Postojna. It indicates some key information about the Postojna power substation and its power supply. The thesis continues by showing the occurrence of ice load in the winter it presents the conditions for the formation of extra loads and areas in Slovenia where sleet is most common. Next it presents a chronological description of sleet occurrence in the Municipality of Postojna in the beginning of 2014 and the impacts on EPS (Electric Power System). At the same time it shows the technical solutions that have been made at this time. A discussion of different power options of the Postojna power substation with graphically and descriptively presented solutions follows. In the conclusion, the author evaluates his work and comments on the presented solutions.

V diplomskem delu je predstavljen postopek priključitve porabnika na nizkonapetostno distribucijsko omrežje, ki je v lasti distributerja Elektro Maribor d. d. Opisan je postopek priključitve porabnika (namakalni sistem) ob naselju Gomilica na nizkonapetostno distribucijsko omrežje in njegov vpliv na druge obstoječe porabnike. Obdelani sta dve varianti priključitve porabnika na nizkonapetostno distribucijsko omrežje. Prva varianta je priključitev porabnika na obstoječe nizkonapetostno distribucijsko omrežje, druga pa priključitev porabnika na nizkonapetostno distribucijsko omrežje z izgradnjo novega izvoda iz TP Gomilica 2 (t-253). This thesis presents a procedure of user connection to low-voltage distribution network, owned by a distributor Elektro Maribor, d.d. Described is a procedure of connection of a user (irrigation system) near a village of Gomilica to low-voltage distribution network, and its impact on other users. Considered are two variants of user connection to low-voltage distribution network. The first one is user connection to existing low-voltage distribution network, while the second one proposes connection of a user to low-voltage distribution network by making a new cable line from transformer station TP Gomilica 2 (t-253).

Vzdrževanje je pomembna funkcija vsake naprave in tako je tudi pri napravah distribucijskega elektroenergetskega omrežja. V prvem delu magistrskega dela sem želel predstaviti razvoj vzdrževanja, pravilnike, standarde in navodila, ter ekonomske predpostavke v vzdrževanju. V nadaljevanju sem se osredotočil na trenutni nivo vzdrževanja. Cilj izdelave magistrskega dela je bil optimizirati vzdrževanje, zato sem določil kritične točke dela elektroenergetskega omrežja s pomočjo analize FMEA. Vsekakor trenutno vzdrževanje ni idealno, zato sem izdelal tudi optimiziranje vzdrževalnih preventivnih ukrepov. Maintenance is an important function of every device, including the devices of distributive electro energetic network. In the first part of the master's degree thesis, I wanted to present the development of maintenance, rule books, standards and instructions, and economic presumptions in maintenance. Further on, I focused on the current level of maintenance. The aim of the master’s degree thesis was to optimise maintenance, which is why I focused on determining critical points of the electro energetic network function with the help of the FMEA analysis. The current maintenance is by all means not ideal, which is why I designed the optimisation of maintenance preventive measures.

V diplomskem delu so analizirana distribucijska omrežja v Sloveniji, Elektro Maribor in organizacijski enoti Slovenska Bistrica, z vidika primerjave med obratovalnimi značilnostmi in stanje njihovih elementov. Predstavljen je postopek zajemanja podatkov pri snemanju nizkonapetostnega omrežja z zastarelo tehnologijo in vnos omrežja v program GIS. Nato je predstavljeno zajemanje podatkov in ustvarjenje projektov z GPS (Global Positioning System), izris in vnos transformatorske postaje v program SDMS. Predstavljene so analize delovanja nizkonapetostnega in visokonapetostnega omrežja s pomočjo programa SDMS, narejena je primerjava med programoma GIS in SDMS z vidika prednosti in slabosti pri vnosu in analiziranju podatkov ob zamenjavi platforme GIS in SDMS. Predstavljene in analizirane so metode za izboljšanje delovanja programa SDMS z vidika hitrejšega in optimalnega delovanja na vseh ravneh. Narejeni so predlogi, podprti s konkretnimi koraki, v okviru finančnih zmožnosti za nadaljnje razvijanje programa, ki bi uporabniku nudil še večje možnosti obdelave in analiziranja podatkov. This diploma work analyses distribution networks in Slovenia, more specifically Elektro Maribor and its Slovenska Bistrica unit, comparing operating characteristics and the state of their components. Diploma describes the data capture procedure when recording data of a low-voltage network with outdated technology and input of the network into a GIS programme. Next, data capture and creating projects using GPS are described as well as presenting and entering data about transformer stations into an SDMS programme. Analyses of the functioning of low-voltage and high-voltage networks are presented using an SDMS programme, and both, the GIS and the SDMS programmes, are compared in view of advantages and disadvantages of data input and analysis when a GIS and SDMS platform is changed. Finally, the diploma work describes and analyses methods to improve the functioning of the SDMS programme in the light of faster and optimal functioning on all levels. Suggestions are put forward, supported by concrete measures, within the financial capability for further programme development, which would give users even better possibilities of data processing and analysis.

V tem magistrskem delu je predstavljena optimizacija proizvodnje razpršenih virov. Ta je izvedena z uporabo algoritma za generacijo referenčnih vrednosti jalove in delovne moči razpršenih virov priključenih v nizkonapetostno omrežje. V predlaganem algoritmu je uporabljena optimizacijska metode diferenčne evolucije in izračun pretokov energije. Referenčne vrednosti jalove in delovne moči razpršenih virov so določene tako, da je zagotovljen ustrezen napetostni profil omrežja. V kolikor je ustrezen napetostni profil omrežja lahko zagotovljen brez omejitve generacije delovne moči razpršenih virov, morajo biti generacije jalove moči razpršenih virov določene tako, da so minimizirane izgube, ki se pojavijo pri prenosu električne energije omrežju. Predlagan algoritem je preizkušen v različnih obratovalni stanjih omrežja, s čimer je potrjena njegova učinkovitost in robustnost. In this master thesis optimization of distributed power generation is presented. The optimization is based on an algorithm that generates references for reactive and active power generation in distributed generation units connected to the low voltage network. In the proposed algorithm the optimization method called differential evolution and load flow calculations are used. The reference values for reactive and active power generation in distributed generation units are determined in that way that an appropriate voltage profile of distribution network is provided. In case that appropriate voltage profile can be provided without active power generation curtailment, then the reactive power generation is determined in that that way, that transmission power losses are minimized. The proposed algorithm is tested under different operating conditions in distribution network in order to prove its effectiveness and robustness.

V diplomskem delu je predstavljena analiza izgub v distribucijskem omrežju pri obratovanju v zanki. V programskem paketu Matlab/Simulink je sestavljen model distribucijskega omrežja, ki vsebuje tuje omrežje, transformatorja, prenose vode in porabnike. Analiza je izvedena za zanki tipa I in II. Zanko tipa I tvorita v zanko povezana izvoda, ki sta napajana iz sponk istega transformatorja. Zanko tipa II tvorita v zanko povezana izvoda, ki se napajata iz sponk dveh različnih transformatorjev v isti razdelilni transformatorski postaji. Uporabljeni so modeli regulacijskih trifaznih transformatorjev z več odcepi. Za različne nastavitve odcepov transformatorjev so predstavljene izgube v omrežju, ki so določene kot razlike moči na začetkih in na koncih posameznih odsekov vodov. The diploma thesis deals with the analysis of losses in a distribution network operating with feeders closed in the loop. A dynamic model of the discussed distribution network is built in the program package Matlab/Simulink. It contains models of a network feeder, transformers, power lines and loads. The analysis is performer for the loops of type I and type II. The loop type I is established by connecting two feeders feed by a single transformer while the loop type II is established by connecting two feeders feed by two different transformers from the same substation. The transformer models with tap changers were used. Losses related with energy transmission in the discussed network are determined for different settings of tap changers.

Teoretski del naloge predstavi vodo kot kemijsko spojino, z nekaterimi lastnostmi, ki so posebej pomembne za človeka in njegovo preživetje. Opredeljeni so parametri za določanje kvalitete pitne vode in vode v vodotokih. Podrobneje je predstavljena oskrba s pitno vodo in nastanek vodovodnega omrežja v občini Ormož, pomen vodnjakov nekoč in danes ter gospodarski pomen vode (poudarek na občini Ormož). V empiričnem delu je predstavljen projekt z naslovom »Kam teče voda«. Zasnovan je bil z namenom seznanitve otrok s pojavnimi oblikami vode v naravi, njenim pomenom za človeka nekoč in danes. Predpostavljeno je bilo raziskovalno in eksperimentalno delo otrok, s katerim so se uresničili osnovni cilji projekta. Izveden je bil v vrtcu Ormož z otroki starimi štiri do pet let. Drugi del empiričnega dela naloge prinaša rezultate anketiranja, ki je bilo izvedeno v vrtcu Ormož. Ugotovili smo, da vzgojitelji za doseganje ciljev, ki so povezani s spoznavanjem vode, odkrivanjem njenih značilnosti in okoljskem ozaveščanju pomena vode, največ uporabljajo metodo opazovanja in razgovora. Vzgojitelji vrtca Ormož se zavedajo pomembnosti teme in otroke seznanijo s pomenom vode za vsa živa bitja. Theoretical part of the thesis presents water as a chemical compound with its characteristics that are especially important for man and his survival. The parameters to determine the quality of drinking water and water in the watercourses are defined. Drinking water supply and the formation of the distribution network in municipality Ormož is more thoroughly presented as well as the importance of the wells in the past and nowadays and the economic importance of water (especially in municipality Ormož). The empirical part presents the project Where is the water running? It was designed with the purpose to educate the children about different forms of water in nature, its importance for man in the past and nowadays. The research and experimental work was assumed to be used to meet the objectives of the project. The project was carried out in the nursery school in Ormož, with children aged 4 to 5. The research showed that the educators mostly use the method of observation and discussion to meet the objectives connected with teaching about water, determining its properties and teaching about the importance of water. The educators in the nursery school in Ormož are well aware of the importance of the subject so children are familiarized with the importance of water for all living beings.

Diplomsko delo obravnava model nizkonapetostnega distribucijskega omrežja, na katerem so priključeni porabniki in proizvajalci. V programskem paketu Matlab/Simulink je sestavljen dinamični model omrežja, ki nam omogoča izvesti analizo napetostnega profila pri različnih obratovalnih stanjih. V modelu so uporabljeni osnovni elementi elektroenergetskega sistema, kot so: transformator, vodi, porabniki in razpršeni viri. Ob vse večjem številu razpršenih virov v naših omrežjih se postavlja vprašanje o kakovosti napetosti in, ali lahko z ustrezno generacijo jalove moči v enotah razpršene proizvodnje vplivamo na napetostne razmere. Prikazani so rezultati simulacijskih izračunov z in brez razpršenih virov. The thesis deals with a low voltage distribution network that consumers and providers are connected to. A dynamic model of the discussed network was developed in the program package Matlab/Simulink. It enables the analysis of voltage profiles under different operating conditions. The model includes basic elements of the power system such as: a transformer, power lines, consumers and distributed power generation units. The increased number of distributed power generation units in our network imposes the question of voltage quality and appropriate generation of reactive power in the distributed power generation units. The thesis shows the calculated voltage profiles considering loads and distributed power generation units.

Diplomska naloga obravnava problematiko izgub električne energije na oslabljenem prenapetostnem odvodniku na transformatorski postaji Kot-Makej (0,95/0,4 kV) in neozemljenem izvoru. Omenjena transformatorska postaja se napaja iz razdelilne transformatorske postaje Ravne (RTP RAVNE) preko 20 kV daljnovoda Mežica in transformatorske postaje Kot (20/0,95/0,4 kV). Rešitev je predstavljena s programskim orodjem MATLAB/Simulink iz knjižnice PowerSystem, s katerim je izvedena simulacija pri oslabljenem prenapetostnem odvodniku. V nalogi je podana rešitev primera. This diploma thesis deals with the losses of electrical energy casued by the aged surge arrester. The discucced surge arrester is connected to the transformer substation Kot – Makej (0, 95/0, 4 kV where, the neutral point of the transformer’s secondary winding is ungrounded. The substation is supplied from the distribution transformer station Ravne (RTP Ravne) through 20 kV transmission line Mežica and transformer station Kot (20/0, 95/0, 4 kV). The analysis of the losses caused by the aged sourge arrester is performed with the model prepared in the program package MATLAB / Simulink using library PowerSystem. The diploma thesis proposes measures for reduction of energy losses that could be caused by the aged surge arresters.

Magistrska naloga opisuje tehnični varianti elektroenergetskega napajanja novega naselja individualnih objektov v Tomačevem (Ljubljana). Opisani sta dve varianti, in sicer, varianta A: napajanje naselja individualnih objektov iz obstoječega nizkonapetostnega omrežja z izgradnjo še potrebnega nizkonapetostnega omrežja ter varianta B: napajanje predvidenega naselja iz obstoječega 10 kV srednjenapetostnega omrežja, v katerega se vključi nova transformatorska postaja 10/0,4 kV z nizkonapetostnim razvodom za predvideno naselje individualnih objektov. Pri ocenjevanju posamezne variante je bil upoštevan kriterij najustreznejše rešitve. Iz tehničnega vidika je bilo za kriterij izbrano dolgoročno saniranje slabih napetostnih razmer na predvidenem območju, upoštevan je bil predvideni odjem moči bodočih odjemalcev električne energije in ekonomski vidik. In the master thesis, two different technical variants of electricity supplay for the settlement of newly built detached houses in the district of Tomačevo (Ljubljana) are being described. In variant A, the power (electric) supplay of the settlement is being created by construction of the power appropriate low-voltage electrical network. In variant B, the power (electric) supplay of the settlement is being derived from already existing 10 kV middle-voltage electrical network, into which, the process of building a new transformer station 10/0,4 kV with the low-voltage cable distribution across the settlement, has been included. The criteria of the most appropriate solution is being considered in assessing the two technical variants. Criteria called long-term sanitation of bad voltage circumstances on the provided area, has been chosen out of technical aspects. The predicted consumption of electric energy of the future residents and the economical aspect of it, have been also taken in consideration.

Ob množičnem vključevanju sončnih elektrarn v elektroenergetsko omrežje se postavlja vprašanje o kakovosti električne energije. Diplomsko delo obravnava vpliv na kakovost električne energije sončne elektrarne priključene na distribucijsko omrežje. Ta je različen od primera do primera, kjer so vključeni številni dejavniki s strani zasnove sončne elektrarne ter prav tako s strani distribucijskega omrežja. Pri tem ima najpomembnejšo vlogo kakovost razsmernika, moč transformatorja in impendanca omrežja. Da bi bili vplivi sončnih elektrarn na omrežje čim manjši, morajo razsmerniki izpolnjevati vrsto zahtev, ki so predpisane s standardi, kot osnovna zahteva pa velja, da mora biti tok, napetost in frekvenca sončne elektrarne skladni s parametri distribucijskega omrežja. Ker na kakovost električne energije v distribucijskem omrežju vplivajo številni dejavniki se je za ta namen vpeljal standard SIST EN 50160, s katerim je postala kakovost električne energije merljiva. Slednje smo raziskali na podlagi meritev kakovosti električne energije skladno z omenjenim standardom pred in po priključitvi sončne elektrarne. Ugotovili smo, da preučeavana elektrarna ni bistveno poslabšala kakovosti električne energije. Zaznali smo povečanje pete in sedme harmonske komponente v toku na izhodu razsmernikov, kateri nista izrazito vplivali na prispevek k obstoječim harmonikom v distribucijskem omrežju. In recent years, importance of solar power plants as a source of electric energy increased, but there are some concerns about the quality of this energy. The aim of the graduation thesis was to study the impact of solar power plant on the power quality in selected distribution network. The latter is determined by both, solar power plant design and distribution network and differs from case to case. The most important factors that influence the power quality are: quality of inverter, transformer power and impendence of the network. To minimize the impact of solar power plant on the distribution network, certain standards for inverter must be followed and current, voltage and frequency of solar power plant must be consistent with distribution network parameters. For power quality measuring, standard SIST EN 50160 was introduced. In our study, voltage quality was measured in agreement with latter standard before and after of connecting the solar power plant to the network. Our results show that solar power plant in studied network did not change power quality. We detected an increase in fifth and seventh harmonic component in current at the inverter exit, but its impact on the distribution network was not significant.

Diplomska naloga analizira vpliv varčnih sijalk na celostno harmonsko popačenje (THD) tokov in napetosti, kakor tudi na izgube povezane s prenosom električne energije v distribucijskih omrežjih nizke napetosti. Potrebni testi in meritve so izvedeni v nadzorovanih pogojih. Vpliv drugih elementov električnega omrežja na rezultate meritev je izločen z uporabo v ta namen sestavljenega eksperimentalnega sistema, ki je izoliran od električnega omrežja. Sestavni elementi eksperimentalnega sistema so vodeni napetostni vir, linearna in nelinearna bremena v obliki varčnih sijalk in žarnic, pa tudi vodniki, ki povezujejo napetostni vir z bremeni. Vodeni napetostni vir zagotavlja enofazne in trifazne napajalne napetosti z majhnim celostnim harmonskim popačenjem ne glede na značaj bremena. Uporabljen je bil za napajanje enofaznih in trifaznih bremen sestavljenih iz varčnih sijalk in žarnic. Na priključnih sponkah vira napetosti in bremen izmerjeni toki in napetosti so bili uporabljeni za ovrednotenje vpliva varčnih sijalk in žarnic na izgube povezane s prenosom električne energije in na celostno harmonsko popačenje tokov in napetosti. The diploma thesis investigates the impact of compact fluorescent lamps (CFLs) on the total harmonic distortion (THD) of currents and voltages as well as losses related with the energy transmission in low voltage distribution networks. The required tests and measurements are performed under controlled conditions. The influence of the distribution network elements not considered in the investigation on obtained results is eliminated by building up an experimental set-up insulated form the electric grid. The experimental set-up consists of a controlled voltage source, linear and nonlinear loads in the form of CFLs and incandescent lamps (normal bulbs) (ILs), and connection lines between the voltage source and loads. The controlled voltage source is able to generate single- and three-phase sinusoidal supply voltages with low THD regardless on the load character. It was used to supply linear and nonlinear single- and three-phase loads composed of CFLs and ILs. Voltages and currents were measured on the terminals of the voltage source and loads. They were used to evaluate the impact of CFLs and ILs on losses related with energy transmission and THDs of currents and voltages.