Transformers parallel operation - economic considerations

Kroz ovaj rad smo ispitali područje isplativosti prijelaza s pojedinačnog u paralelni rad za određene modele transformatora. Da bi uopće bio moguć paralelni rad transformatora, transformator mora zadovoljiti sljedeće uvjete: ista grupa spoja, isti prijenosni omjer, približno jednaki nazivni naponi i naponi relativnog kratkog spoja te omjer nazivnih snaga ne smije biti veći od 2. Nadalje, analizirali smo gubitke u transformatorima, definirali smo granična opterećenja i faktore opterećenja do kojih je isplativo raditi s jednim transformatorom, dva transformatora ili tri transformatora u paraleli, te smo prema njima nacrtali i dijagrame. Kao i kod pojedinačnog tako i u paralelnom radu s dva ili tri transformatora, za veće transformatore optimalniji je rad s manjim faktorom opterećenja u odnosu na transformatore manjih snaga, gdje je optimalniji rad s većim faktorom opterećenja. U današnje vrijeme se sve manje koristi paralelni rad transformatora kao standardni oblik napajanja mrežnih sustava, jer se koriste transformatori veće nazivne snage te se samo javlja potreba za paralelnim radom kod prespajanja transformatora preko spojnog polja, te u slučaju kvara. Da bi dokazali gore navedeno, u zadnjem poglavlju smo napravili analizu TS “Krk“ te smo nacrtali dijagrame po periodu dana u ovisnosti o radnoj i jalovoj snazi.In this paper we have investigated the area of cost-effectiveness of transition from single to parallel operation for certain transformer models. In order to be able to perform the parallel operation, the transformer must meet the following conditions: the same group of connections, the same transmission ratio, approximately the rated voltages and voltages of the relative short circuit, and the nominal power ratio should not be greater than 2. Furthermore, we have analyzed the losses in transformers , defined the boundary loads and load factors that it is cost-effective to work with a single transformer, two transformers or three transformers in parallel, and draw diagrams accordingly. As in operation of single transformer, as in parallel operation with two or three transformers, for larger transformers, it is more optimal to work with a lower load factor than the smaller power transformers, where it is more optimal to work with a higher load factor. Nowadays, the parallel operation of the transformer is no longer used as a standard form of power supply of the network systems, because higher rated power transformers are used, and there is only a need for parallel operation when converting the transformer through the connection field and in case of failure. To prove the mentioned above, in the last chapter we made an analysis of the TS "Krk" and we drew diagrams per period of time depending on the working and refractive power