Study On Power System Voltage And Reactive Power Control Method

Ultra High Voltage transmission and wind power connecting to the grid on a large scale are the two major issues needed to be solved. Due to high voltage circuit charging power caused by high voltage level of the UHV transmission line, overvoltage and steady-state voltage reactive-power problems should be fully researched. What's more, the low voltage ride through problem of the wind turbine has always been the key issue of the wind power connecting to the grid. Aiming at the problems above, this paper do some research on Power System Voltage and Reactive Power Control Method.Firlstly, aiming at the reactive power layer and district partition balance problem, this article introduced voltage reactive-power zoning control method based on fuzzy clustering, and put forward the regional coupling index evaluation division results based on voltage-reactive power quality. This method is simple and clear of physical conception, it was used in hubei province power grid partition control, and the validity was verified in PSASP. Partition result and choosen dominant node provide a good guidance for voltage control.Secondly, in view of the characteristics of the steady-state overvoltage high-voltage road, this paper emphased on the infulence of casting capacitors to voltage control domain. Found that using the commonly used algorithms, input capacitor causes the voltage drop along the high voltage lines, this conclusion is inconsistent with the actual situation.Through careful anylasis, this paper found that the adopted infinite power model as well as the reactance negative value characteristic of medium-voltage side of the transformer windings is the main reason for casting capacitor caused UHV along voltage drops. On this basis, this paper studied termingal voltage control domain and capacitor casting policy, writed UHV voltage control domain software which has practical value.Finally, the low voltage ride through ability is an important performance measurement of the wind turbine, traditional method adopts parall resisitance in the rotor side to keep the rotor from over current. But, if the reactive power capacitance is enough, we can consider taking other methods for control. Because the self-learning characteristic of neural dynamic programming method, it can deal with nonlinear dynamic system, the auther considered using this method in the wind farm system for reactive power control. Based on Matlab/Simulink set of simulation system, the auther designed the controler, the simulation results proved that the controller can restrain the voltage and power oscillation.