KOMPARATIVNA ANALIZA RAZLIČITIH METODA DISPEČINGA REAKTIVNIH SNAGA IZMEĐU GENERATORA U ELEKTRANI

Abstract

Two methods of reactive power dispatching between generators in the power plant are presented in the paper. Total reactive power required is deployed between generators connected to the power grid and the load coefficients are maintained evenly. According to the first method, “per grid”, load coefficients are determined as a ratio of generated reactive power and total generator available reactive power range. According to the second method, “per generator”, load coefficients are determined depending on the sign of total reactive power required. If the total reactive power required is positive (on the terminals of the generator), load coefficient is determined as ratio of generated reactive power and positive part of total generator available reactive power range (from zero to maximal ractive power available), and if the total reactive power required is negative, load coefficient is determined as ratio of absorbed reactive power and negative part of total generator available reactive power range (from minimal ractive power available to zero). The advantage of the first dispatching method is that all the generators simultaneously reach their lowest and highest allowed values, Qmin and Qmax, and then simultaneously activate excitation limiters when the grid voltage varies. The advantage of the second dispatching method is maintaining of the terminal voltages of the generators evenly, which has the favorable influence on the generator lifespan. Only if the terminal voltage of the generator is the limiting factor, this method also enshures reaching Qmin and Qmax at the same time and simultaneous limiter activation