Combined Cycle Power Plant in Frequency Regulation

Sa sve većim brojem obnovljivih izvora, narušava se stabilnost elektroenergetskog sustava zbog trenutnih odstupanja između potrošnje i proizvodnje električne energije. Nedostatkom kapaciteta za primarnu i sekundarnu regulaciju s brzim odzivima promjene snage u odnosu na instalirane kapacitete iz obnovljivih izvora energije, sve se više razmatra mogućnost rada kombi elektrane u svrhu regulacije djelatne snage. U radu su analizirane mogućnosti korištenja kombi elektrane u regulaciji djelatne snage i frekvencije. Regulacija se postiče radom kombi bloka u djelomičnom opterećenju, gdje isporučuje manje izlazne snage nego što je to nominalno moguće pri trenutnim okolišnim uvjetima, no s tim se i pogoršavaju performanse elektrane. Dinamika plinsko – parnog kogeneracijskog bloka se razmatra s ciljem promatranja brzina prijelaznih pojava unutar sustava. Kogeneracijska elektrana je matematički modelirana, te su sve jednadžbe za svaki dio integrirane u jedan blok koji se nametnutim poremećajima izbacuju iz stacionarnog stanja te se promatra tromost sustava za postizanje novog stacionarnog stanja. Ekonomska isplativost je bitno narušena kod rada pri smanjenom opterećenju, s obzirom na investicijski trošak cijelog postrojenja. Ako je ekonomski opravdano, elektrana može raditi s smanjenim kapacitetom, te za to dobiva godišnje naknade.With an increasing number of renewable energy sources, that challange the stability of the power system due to the current diffrence between consumption and production of electricity. The lack of capacity for the primary and secondary power reserve, that have fast response of power in relation to the installed capacity, has to be taken as a problem and the combined cycle power plant is a possible solution. The paper analyzes the possibilities of combined cycle power plants in the regulation of active power and frequency. Regulation is achieved by operating the combined-cycle unit at partial load, which delivers a lower power output than is possible with nominal current environmental conditions, but working at partial load decreases both performance and power. The dynamics of gas-steam cogeneration unit is considered with the aim of observing speed transients within the system. Each component of the scheme is mathematically modeled, and all the equations for each part are integrated in a block that is imposed by the disturbance thrown from the stationary state and the system achieves a new steady state. Economic benefit is significantly impaired when operating at reduced load, in view of the investment cost of the plant. If the economic oporavdano, power plants can operate with reduced capacity, and it gets to the annual fee