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U ovom završnom radu razmatra se mogućnost korištenja automatske regulacije napona na srednjonaponskoj razini. U radu navedeni su glavni dijelovi elektroeneretskih sustava te primjena i kvalitetna dostava električne energije do krajnjih potrošača. Shodno tome rad nadalje govori o rasklopnim postrojenjima. Radom je dan detaljan opis od čega se sastoji rasklopno postrojenje i detaljno je opisan svaki element rasklopnog postrojenja. Nadalje rad objašnjava osnovni princip rada transformatora, njegove gubitke, režime rada i odnose struja i napona u različitim režimima rada. Specijalne izvedbe transformatora također su obrazložene u radu. Glavni dio ovo rada je mjenjač izvoda pod opterećenjem - OLTC (eng. On-load tap changer). Rad objašnjava transformatore s promjenom prijenosnog omjera pod opterećenjem, raspored namota i gubitak opterećenja sustava s jednim kontaktnim prebacivanjem. Rad analizira različite rasporede namota u OLTC i detaljno ih opisuje. Opisan je OLTC uljnog tipa i vakuumski tip OLTC-a, dani su parametri na koje moramo pripaziti kod odabira OLTC-a. Rad sadrži i praktični dio koji je bio odrađen kod HEP ODS Elektra Čakovec. U praktičnom radu obrađuje se utjecaj sunčane elektrane SE Čakovec na naponski profil u pojnim točkama elektroenergetske mreže Elektre Čakovec. Simulacije su rađene u programu ''Neplan''. Iz shema možemo vidjeti kako automatska regulacija održava i mijenja po potrebi napon mreže i promjene napona SE Čakovec pri minimalnom i maksimalnom opterećenju. This final paper discusses the possibility of using automatic voltage regulation at medium voltage level. The paper lists the main parts of the power system and applies the quality of electricity supply to end users. Accordingly, the paper talks about switchyards. The paper gives a detailed description of what a switchyard consists of and describes each element of switchyards in detail. Furthermore, the paper explains the basic operation principle of a transformer, its losses, operating modes and current and voltage relations in different operating modes. Special transformer designs are also explained in the paper. The main part of this paper is the On-load tap changer – OLTC. The paper explains transformers with change of load ratio under load, winding arrangement and load loss of systems with one contact switching. The paper analyses different winding arrangements in OLTC and describes them in detail. Oil type OLTC and vacuum type OLTC are described, the parameters that must be taken into account when choosing OLTC are given. The paper also contains a practical part that was done at HEP ODS Elektra Čakovec. Practical paper deals with the influence of the solar power plant SE Čakovec on the voltage profile in the connection points of the electric power network of Elektra Čakovec. Simulations were done in the ''Neplan'' program. We can see from the diagrams how the automatic control maintains and changes the voltage as needed. We can also see changes in the voltage of SE Čakovec at minimum and maximum load.

U ovome je radu objašnjena potreba za upravljanjem elektroenergetskim sustavom (EES), te je dan kratak pregled vrsta upravljanja u EES-u. Prvi dio rada daje pregled vrsta regulacija u EES-u, te su navedene prednosti i nedostaci pojedinih razina regulacije s naglasakom na regulaciju napon. Kako bi se projektirao regulator napona izveden je linearni matematički model sinkronog generatora i njegovog uzbudnika, što je prikazano u drugom dijelu rada. Pri tome su detaljno opisane sljedeće komponente sustava: sinkroni generator, uzbudnik i regulator napona. Analizirana je dinamika generatora povezanog na EES-a kako bi se odredila vrsta regulacijske staze regulatora napona generatora, te su projektirani i PI regulator. U trećem dijelu rada izrađen je simulacijski model sustava te je provjerena kakvoća regulacije korištenih regulatora napona. Simulacija je provedena u programskom paketu Matlab/Simulink. The need for voltage and reactive power control of the electric power system is explained in this paper. The first section describes the type of regulation in the electric power system and gives overview of advantages and disadvantages of different levels of control, with emphasis placed on voltage control. In order to design the voltage regulator, a linear mathematical model of synchronous generator and its exciter is given, which is presented in the second section, where the following system components are described in detail:a synchronous generator, an exciter and voltage control. The dynamics of the generator connected to the power system were analyzed to determine the type of control path of the generator voltage control, and the and the PI controller were designed. In the third section, a simulation model of the system was developed and the quality of the used voltage controller was checked. The simulation was performed in Matlab/Simulink software.

Tema ovog diplomskog rada je dati detaljniji uvid u djelovanje i primjenu sinkronog generatora s istaknutim polovima. Opisane su tehničke specifikacije sinkronih generatora s istaknutim polovima, te su pokazane konstrukcijske i upravljačke razlike u odnosu na generator s cilindričnim rotorom. Pomoću fazorskih dijagrama i karakteristika snage i momenta postavljena je teorijska podloga za izradu proračuna. U računskom dijelu izrađene su karakteristike snage i momenta za generator velike snage HE Vinodol, te generator znatno manje snage mHE Pleternica. Također su prikazane mogućnosti varijacije izlazne snage na generatoru kroz promjenu radnih točki upravljanjem faktora snage i protoka kroz hidroelektrane The theme of this Master's thesis was using and application of salient pole synchronous generators. Technical specifications of salient pole synchronous generator are described, as well as the main construction and control difference from cylindrical pole generators. Using the phasor diagrams, power and torque characteristics a theoretical basis for calculation have been set. Power and torque characteristics were calculated for the high-power hydro plant HE Vinodol, as well as for the much smaller hydro power plant mHE Pleternica. The research also showed the possibility of variation of output power switching between generators working points, by changing the flow of the water and controlling the power factor of the generator