A. Safaei - MSC Student, Amirkabir University of Technology
H. Mahdinia Roodsari - MSC Student, Amirkabir University of Technology
H. Askarian Abyaneh - Professor,Amirkabir University of Technology

In general, The Frequency is a vital characteristic of the network and allowed frequency deviation restricted to a few percents of one Hertz. The frequency of an isolated smallhydropower plant is controlled using a dump load and on/off valve control. The water flowing through the penstock is redirected in smaller pipes, three fixed with motor operatedvalves while opening and closing of the valves is attained by on/off controls. On/off control is utilized in order to reduce thesize of dump load because the dump load is a high cost apparatus. However, disadvantage of this method is a largedeviation in the frequency of the hydro-generation units. In this paper, a PI controller has been used to reduce the peak of frequency deviation. The optimal gain of PI controller andintegrator of dump load is obtained by genetic algorithm (GA) to achieve minimum frequency deviation. In this method, thepeak of frequency deviation is reduced less than one Hz while in the conventional scheme, the peak of frequency deviation is three Hz. In other words, the positive or negative peak of frequency deviation has been reduced about 60%.

Small Hydropower Plants, Load Frequency Control, Optimal Controller, Genetic Algorithm (GA