Analysis For Effect Of The Reactive Controlled Unit On Generator Dynamics

The Reactive controlled unit to ensure the power system reactive power distribution and improve the voltage quality is critical. The Reactive controlled unit will directly affect the Excitation system dynamics, which affect the running characteristics of the Power system stabilizer(PSS), so need to consider the Reactive controlled unit when studying the characteristics of the PSS.In order to study the influence about the Reactive controlled unit to the PSS and the Excitation system on frequency characteristics, need the relationship between the Excitation system output fd?E and the Excitation system input t?V after considering the Reactive controlled unit, but accurate generator model is a closed loop system, it would be difficult to get the relationship expression. Therefore, on the basis of the dynamic expression and accurate considering its transmission block diagram of generator and the additional controller, establish a single machine infinite system of six order generator accurate linear model, including the Reactive controlled unit, the Excitation system(EXC) and the Prime mover(GOV), etc. Accurate linear model is used to establish differential or algebraic equations, elimination of the non-state variables, using the method of equation transformation, obtained relatively accurate state space expression between fd?E and t?V.Paper first use the original parameters of generator in the grid in Henan province, and under the effect of the PSS, analysis the output phase frequency characteristics of the Excitation system. Then write complex Gaussian elimination program by Fortran programs, elimination of the non-state variables which in linear equation, then obtain the relationship between the generator Excitation system outputfd?E and the Reactive controlled unit inputt?V, so get the input of the Reactive controlled unit. Then, it would be convenient to calculation after joining the Reactive controlled unit. Examples listed the four different capacity of the generator phase frequency characteristic and analyzed them. By comparing the unit part list consideration and not consider the Reactive controlled unit phase frequency characteristics, it is concluded that in the case of a single machine infinite system, join the Reactive controlled unit will make phase frequency characteristics of excitation control system as a whole down.Each generating unit has its own electromechanical oscillation frequency, under the condition of single power input PSS, if we can make excitation control system provide-90 degree Angle relative to the shaft ?? in the corresponding frequency, in theory, it also provides maximum damping torque conditions. According to the above principle, consider the Reactive controlled unit of four sets of machine, after adjusting the PSS phase shift link time constant, the excitation system under the free oscillation frequency provide-90 degree Angle relative to the shaft ??, to provide some references for the scene setting to compensate the frequency characteristics of the PSS.