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The paper presents the possibility of using ERP business software for the purpose of analyzing steady states of electric drives. A centrifugal pump is used as an example of active load. After reviewing previous research and presenting the basic principles of using the ERP model, the analysis of the operation of the centrifugal pump and the processing of the results of the propulsion measurements were approached. Two flow control options are considered and both methods are compared regarding energy consumption. After that, the method of calculating energy saving using the ERP model is shown. The calculation results provide data on different costs depending on the type of flow control. Since an induction motor with a frequency converter is provided for flow control by changing the speed, the final step is rough profitability estimate of the investment in frequency converter, which was also done directly in the ERP model.

The article presents the application of simulation tools through the example of operation and failure in a real power grid. The history of simulations dates back to the early 1940s. With the development of digital computers and advanced software, simulations are finding more and more application. With well-modeled elements of the simulated system, it is possible to analyze the operation as well as test the system in different situations in order to predict the possible consequences of disturbances in the operation of the system. By connecting this modeled system with a real system, and entering real data and events in real time, the concept of digital twins combined with machine learning was created, with the aim of finding optimal strategies that will result in appropriate decisions and actions depending on process changes.

The System Integrity Protection Scheme (SIPS) is a specialized protection scheme which differs to a great extent from the common protection, especially in its main intention. It is designed for integrity protection, failure prevention and mitigation of disturbance consequences in the whole power system (PS) or modern distribution system (MDS) with a significant power of distributed generation (DG). The input parameters for establishing SIPS in PS are synchronized phasor measurements obtained from the Phasor Measurement Units (PMUs), as a globally acknowledged Smart Grid technology. The realization requires that SIPS is added to the existing Wide Area Monitoring, Protection and Control (WAMPAC), based on synchronized measurements. This paper proposes an algorithm that anticipates optimal PMU placement and then uses angular stability protection based on traditional IEDs supported by synchronized measurements. By using such approach, the system avoids possible blackouts due to the combined operation of the traditional protection and WAMPAC. The proposed SIPS system is tested on specific area in the Croatian transmission system integrating hydro power and wind energy converting power plants. Due to the increased power of renewable energy sources (RES), the proposed algorithm is applicable to modern distribution systems.

In today's business environment, investing in information technology is more than remunerative. To recive the real state of a company, the key element is the realization and implementation of the complete ICT solution. To prepare and realize such a complex system, continuous interaction of all participants is required, from the top management to direct participants of each production segment: personnel in the financial and accounting sectors, planning and analyzing sector, procurement and sales personnel, logistics, occupational safety and quality control... In addition to human resources, proper hardware support is also needed built into the automated machines and devices within the manufacturing location that will deliver operational data to the system. In order to survive and be competitive in the market today, the access to the right information in the shortest possible time is essential. Data warehouses and business intelligence form the foundation on which business people make their strategic and tactical business decisions. The ability to analyze snapshots of the observed subject's state of affairs in the past and to look for similarities and differences in behavior over a period of time makes one of the greatest advantages of the data warehouse over previous transaction systems. Newer technology has enabled the development of ETL (Extract, Transform and Load) applications with minimal delay, and thus the emergence of data warehouses that work in real or near real time. This paper provides guidelines for the development and design of a comprehensive ICT solution and addresses some of the consequences that this solution could have for modern businesses.

This doctoral thesis focuses on the efficient management of a power system with a large share of wind-power generation and on the methods for planning the operating reserve. The approach proposed in this research involves the use of data directly from the network’s dispatch center and the forecasting systems, as well as already existing day-ahead plans for wind and load power to determine the regulating reserve for the load frequency control (LFC). The same principle is used to find the optimal regulating reserve distribution (RRD) between the available generation units in the system for automatic generation control. It is developed using iterative power-flow computation with a reactive power correction and a stochastic search algorithm for transmission-loss minimization. Moreover, variations in the generation of individual wind-power plants (WPPs) from the plan are considered in the optimal RRD. A special focus of this research has been put on the Croatian power system due to the accessibility of relevant information and operating data. The obtained results of the testing with actual data from the Croatian power system indicate substantial savings in ancillary service costs for the LFC, while ensuring safe system operation. The considerable impact of variations from the plan for each individual WPP generation on the optimal RRD was also identified. Comparing the results for the daily sum of regulating reserves obtained with the proposed and the currently used approaches, the corresponding costs indicate a total saving of 21.2% for all 12 selected days in 2015 when using the proposed approach. In practice, a part of the reserve can be slow, i.e., with a lower unit price, thus the savings would be even higher. Furthermore, the obtained optimal RRD computed according to the proposed approach was compared with four commonly used RRDs in Croatia. The results obtained using the proposed approach indicate a decrease in the total transmission losses of between 1% and 2%. With a larger share of the generation from the WPPs and with more dispersed locations of the WPPs and regulating power plants a larger reduction in the transmission losses is expected. Doktorska disertacija se osredotoča na učinkovito upravljanje elektroenergetskih sistemov z velikim deležem vetrnih elektrarn in na metode za načrtovanje obratovalnih rezerv. Predlagani pristop za določitev rezerve za regulacijo moči in frekvence vključuje uporabo podatkov neposredno iz centra vodenja in sistemov za napovedovanje, kakor tudi obstoječih dnevnih načrtov proizvodnje vetrnih elektrarn in obremenitve. Enak princip je uporabljen za iskanje optimalne porazdelitve regulacijske rezerve med razpoložljive proizvodne enote, ki so v sistemu za samodejno regulacijo proizvodnje. Razvit je z uporabo iterativnega izračuna pretokov energij s korekcijo jalove moči in z uporabo stohastičnega iskalnega algoritma za zmanjšanje prenosnih izgub. Poleg tega se pri izračunu optimalne porazdelitve regulacijske rezerve upoštevajo razlike med dejansko in načrtovano proizvodnjo posameznih vetrnih elektrarn. Zaradi dostopnosti do ustreznih informacij in obratovalnih podatkov je bil poseben poudarek te raziskave na hrvaškem elektroenergetskem sistemu. Dobljeni rezultati za dejanske podatke iz hrvaškega elektroenergetskega sistema kažejo na precejšne prihranke pri stroških sistemskih storitev za regulacijo moči in frekvence, pri čemer je zagotovljeno varno obratovanje. Identificiran je bil tudi znaten vpliv odstopanj med dejansko in načrtovano proizvodnjo posameznih vetrnih elektrarn na optimalno porazdelitev regulacijske rezerve. Primerjava rezultatov za dnevno vsoto regulacijske rezerve, dobljene s predlaganim in trenutno uporabljenimi pristopi kaže, da predlagani pristop za 12 izbranih dni v letu 2015 zniža skupne stroške za 21,2%. V praksi je del rezerve lahko počasen (nižja cena na enoto), zato bi bili prihranki lahko še višji. Optimalno porazdelitev regulacijske rezerve smo primerjali s štirimi pogosto uporabljenimi porazdelitvami na Hrvaškem. Dobljeni rezultati kažejo, da se skupne prenosne izgube ob uporabi predlaganega pristopa zmanjšajo med 1% in 2%. Večje zmanjšanje prenosnih izgub bi lahko dosegli z večjim deležem proizvodnje iz vetrnih elektrarn in z bolj razpršenimi lokacijami vetrnih in regulacijskih elektrarn.

The paper presents results of a research made by teachers of undergraduate electrical engineering students in determining the significance of using didactic tools in order to increase the students` motivation to participate actively in the teaching process. Converters used in this research are designed and modelled by students themselves for laboratory power-electronics exercises. It is shown that using didactic tools improves understanding of complex subjects when the students have the opportunity to link practical exercises with the theoretical explanations given in lectures.

Ovaj članak prikazuje rezultate istraživanja i analize postojećeg postupka planiranja snage sekundarne i tercijarne rezerve u Hrvatskom kontrolnom području, kao i različitih determinističkih i probabilističkih metoda predloženih u znanstvenoj literaturi, odnosno primijenjenih u drugim zemljama. Predlaže se novi način izračuna potrebnog raspona rezerve snage za naredni sat u pozitivnom i negativnom smjeru, uzimajući u obzir tendenciju promjena iz prethodnih sati. Pri tome se promatraju proizvedeni iznosi iz svake vjetroelektrane zasebno, kako bi se omogućile različite korekcije planova za vjetroelektrane koje su prostorno udaljene, odnosno koje nisu obuhvaćene istim vjetrom, ovisno o promjeni vremenskih uvjeta u tom području. Predloženo rješenje je testirano s realnim operativnim podatcima iz hrvatske prijenosne mreže za odabrane karakteristične dane u 2015. godini, te pokazuje mogućnosti značajnih ušteda u troškovima pomoćnih usluga.

The article presents the solution of heating and cooling using a heat pump on building no. 3 of the University North in Varazdin. After the description of the principle of heat pump operation, the technical data of the installed heat pump are listed and the remote control system is described. Finally, significant process data are presented that can be remotely monitored, in order to analyze the functioning of the system.

V članku so obravnavani različni modeli verjetnostne porazdelitve napake proizvodnje vetrnih elektrarn. Poleg modelov, znanih iz literature (beta, Weibull, gamma), so obravnavani modeli z razširjeno nesimetrično posplošeno normalno porazdelitvijo. Obravnavan je tudi model s t.i. verzatilno verjetnostno porazdelitvijo, ki je občutljiv na valovitost empirične porazdelitve, vendar omogoča analitičen izračun percentilne funkcije. Dobljeni rezultati kažejo, da modeli z beta, Weibull in gamma verjetnostno porazdelitvijo ne dajejo dobrih rezultatov, bistveno bolj ustrezni so modeli z nesimetrično posplošeno normalno verjetnostno porazdelitvijo.

Pogon elektroenergetskih sustava postaje sve zahtjevnije s povećanom integracijom obnovljivih izvora energije, koji se često nadziru samo na daljinu. Stoga, njihova moderna upravljačka oprema treba omogućiti siguran rad, uz pružanje dovoljnih podataka za daljinski nadzor. U ovom se radu opisuje laboratorij za obnovljive izvore energije instaliran na Odjelu za elektrotehniku Sveučilišta Sjever. Središnji dio sustava je fotonaponska solarna elektrana u otočnom režimu rada sa četiri monokristalna i četiri polikristalna modula, dva odvojena regulatora punjenja te solarnim invertorom. Ugrađena kontrolna oprema omogućava daljinski nadzor i pohranu podataka o radu za naknadnu obradu i analizu.

This article shortly describes the solar power plant built on the roof of Crnec municipality building and shows the difference between actual and designed production of electricity. As example, the selected solar power plant shows the impact of module shading on electricity production and the possibility of their reduction. Moreover, the difference in production is analyzed depending on the position of the module towards the Sun in different seasons.

This article describes the main elements of solar power plant built on the roof of the student restaurant in Varaždin, the used grid inverters in particular. Moreover, the way of connecting the photovoltaic cells on grid converters and user’s installation is presented. At the end of this paper, there is a review of electrical energy production during the first five months of operation.

U radu je opisan realizirani inteligentni sustav za pametnu kuću. Koriste se gotovi mikrokontrolerski moduli koji imaju mogućnost međusobne komunikacije. Uz odgovarajuće dodatne sklopove realizirano je upravljanje grijanjem i svjetlima i objašnjeno kako se sustav može koristiti za nadzor i upravljanje drugim procesima u kući i izvan nje. Realizirano je i upravljanje funkcijama preko daljinskog upravljača pomoću infracrvene veze, te je realiziran prikaz na LCD ekranu. Opisane su hardverske i softverske komponente te funkcionalnost cijelog sustava.

Člankom je dan pregled tijeka izgradnje i puštanja u rad sunčane elektrane postavljene na krov studenskog restorana u Varaždinu. Opisane su postavljene solarne ćelije, pretvarači, elektro razvod sa komponentama, te odabir smještaja i način montaže. Objašnjeno je povezivanje sustava i puštanje u pogon, uz sve preduvjete koje postavlja distribucijsko područje, u ovom slučaju HEP ODS Varaždin, kao i problematika koja se javlja na terenu tijekom izgradnje.

This article describes the way of connections and control of nowadays wind power plants connected to fixed power network, and presents problems that are caused by wind plants because their operative instability. It is also described topology of a newer with better regulations capabilities then today commercial used grid converters. At the end of this paper there is a review of existing wind power plants in Croatia and those in construction with guidelines for improvement of system stability with high wind energy penetration

U radu su opisane smetnje koje mogu djelovati na elektromotor tijekom rada elektromotornog pogona, te elementi koji služe za zaštitu elektromotora od različitih nepovoljnih stanja. Na primjeru promatranog pogona opisana su dva problema koja su se pojavila u elektromotornom pogonu pilane i njegovo adekvatno rješenje.

U članku je opisan način rada postrojenja Aertecnica, predložene izmjene ugradnjom frekvencijskog pretvarača, te su opisane njegove karakteristike i prednosti. Na kraju su izračunati godišnji troškovi potrošnje električne energije za EMP bez ugrađenog frekvencijskog pretvarača, izračunati su troškovi ugradnje frekvencijskog pretvarača i ostalih potrebnih elemenata. Izračunat je i rok povrata sredstava kroz uštede na održavanju i štednji električne energije.

Primjena programabilnog logičkog kontrolera (u daljnjem tekstu PLC, od engl. Programmable logical controller) u automatizaciji danas je već znatno raširena, moglo bi se reći „nije ništa novo“. Ipak, kad se kaže da je upravljanje nekim strojem, uređajem ili postrojenjem izvedeno PLC-om, većina automatski očekuje kompliciranu i svakako skupu automatiku. Istina je da ozbiljnije, složenije i zahtjevnije izvedbe upravljačkih sklopova danas podrazumijevaju primjenu PLC-a, čak i više njih umreženih u sustav. Cilj je ovog rada pokazati da postoje izvedbe upravljanja manje razine složenosti kod kojih može biti ekonomski opravdana primjena PLC-a.

Rad objašnjava način korištenja programa izrađenog na Zavodu za visoki napon i energetiku za proračun prijelaznih elektromagnetskih pojava u mrežama i postrojenjima. Uz to objašnjava način zadavanja parametara i ispisa rezultata na test primjerima iz visokonaponskih i distributivnih postrojenja.

U ovom radu obrađeno je idejno rješenje visokog stupnja automatizacije procesa paletizacije. Obrađeni proces paletizacije je završni proces postojećeg sustava za pakiranje robe u logističko-distributivnom centru. Objašnjeni su pojmovi industrijske automatizacije, paletizacije i idejnog projekta. Opisani su i objašnjeni podsustavi, odnosno dijelovi postrojenja koji su zaduženi za specifične zadatke i koji zajedno tvore cjelinu. Navedena je sva korištena elektronička oprema, a najznačajnija oprema detaljnije je analizirana, opisan princip rada, prikazani nacrti i spojne sheme. Opisano je kodiranje Interleaved 2/5 bar kod oznaka. Opisana su programska rješenja za upravljanje procesom, procesuiranje podataka i protok informacija te korisničko sučelje za nadzor i vizualizaciju procesa. U konačnici ovog rada analiziran je cjelokupni sustav s naglaskom na prednosti automatizacije procesa paletizacije, no i njenim manama. Sustav je uspoređen sa sličnim postrojenjima koji se koriste u pakirnoj industriji.

U ovom radu opisane su pojave na kojima se bazira rad termoelektričnih modula, princip rada termoelektričnog generatora i materijali od kojih se izrađuje. Navedene su prednosti i ograničenja te područja primjene termogeneratora. U praktičnom dijelu opisani su uređaji za regulaciju temperature termoelektričnih hladnjaka i demonstriranje termoelektričnih efekata na modulima, a zatim su provedena testiranja na dvama termoelektričnim modulima. Rezultati mjerenja su prikazani tablično i grafički. The phenomena on which the operation of thermoelectric modules is based, working priciple of thermoelectric generator and materials from which it is made are described in this paper. Advantages and limitations are listed as well as application areas of thermogenerators. In the practical part, devices for temperature regulation of thermoelectric coolers are described as well as devices for demonstrating thermoelectric effects on modules. The results of measurements are presented tabularly and graphically.

U ovome radu biti će obrađeno održavanje računala i računalnih sustava. U uvodnome dijelu rada biti će predstavljeni osnovni problemi održavanja sustava. Nakon uvodnog dijela biti će prezentiran odabir sustava i održavanje ovisno o potrebama korisnika. U četvrtom poglavlju rada biti će prezentirane glavne komponente računalnog sustava te kako ih bolje održati. U petom poglavlju rada biti će predstavljeni problemi kod zlonamjernih softwera, malwera i cyber napada te kako se zaštiti od tih istih problema. Na samom kraju rada sagledati će se analiza istraživnaja pristupačnosti dobavljača računalnih sustava. Cilj ovo završnog rada je dati korisnicima uvid u održavanje raznih sustava u raznim okolinama i s raznim komponentama. Također kornisnicma se daje uvid u dobavljače računalnih sustava tako da sami mogu odlučiti s kojim dobavljačem žele poslovati. This paper will process maintenance of computers and computer systems. The introductory part of this paper will present the main problem in maintaining systems. After the introductory part, the paper will present selection of systems and their maintenance depending on user needs. Fourth chapter of this paper will present main components of computer systems and how to better maintain them. Fifth chapter of this paper will present the main problem of malicious software, malware and cyber attacks and how to protect from those same problems. Analysis of computer systems vendor accessibility research will be shown at the very end of this paper. The goal of this final paper is to give users insight in maintenance of systems in different environments and with different components. Users are also provided with insight of computer systems vendors so that they can decide with which supplier do they want to do business.

U ovom završnom radu prezentirat ću automatizaciju stambenog prostora pomoću HDL uređaja i računalnog programa HDL Bus Pro. U uvodnom djelu završnog rada opisane su prednosti pametnih kuća, drugi dio rada odnosi se na zahtjeve investitora, opremu koja se koristila za ovaj projekt, treći dio rada odnosi se na konfiguraciju navedenih uređaja i na kraju četvrti dio rada odnosi se na izradu i korištenje Magiesta aplikacije koja se koristi za upravljanje pametnom kućom kad se nalazimo izvan nje Automatizirati će se rasvjeta, zavjese, grijanje i hlađenje. Cilj ovog završnog rada je pokazati prednosti pametnih kuća, jednostavnost korištenja sustava te uštedu energije koju pametna kuća donosi. In this final thesis, I'll present the automation of the living space by using HDL devices and their software, HDL Bus Pro. In the intro of the thesis, I've described the benefits of smart houses, the second part refers to the demands of the investors, the equipment which was used for the project, and finally, the last part explains how to make an app with Magiesta, which is used to control the house, and its smart functions when the tenants aren't present. We automated the lighting, heating, cooling, and curtains. The goal of this final thesis is to explain and present the benefits of smart houses, the simplicity of the management system, and how all elements contribute to saving energy for the owners.

U ovom radu ukratko su definirani motori i razlike između sinkronih i asinkronih motora, frekvencijski pretvarači kao i njihove vrste i način rada. Osnovna svrha rada bila je izraditi prototip automatizirane vodoravne tračne pile kojom se upravlja pomoću PLC i HMI uređaja. Rad daje detaljan pregled koraka programiranja PLC-a, kao i slikovni izgled konačnog proizvoda. Predstavljeni su svi korišteni uređaji, kao i alat za programiranje PLC i HMI uređaja Step7 verzije 5.6. Operater koji radi na stroju njime komunicira putem HMI uređaja unošenjem potrebnih veličina. In this paper, motors, differences between synchronous and asynchronous motors, frequency converters as well as their types and mode of operation are briefly defined. The main purpose of this paper was to make a prototype od an automated horizontal band saw which is controlled by PLC and HMI devices. The paper gives a detailed overview of the PLC programming steps, as well as a pictorial appearance of the final product. All used devices are presented, as well as the tool for programming PLC and HMI devices Step7 version 5.6. The operator working on the machine communicates with it via a HMI device by entering the necessary values.