Study On Control Strategy With Stepped Controllable Shunt Reactor In Large-scale Wind Power Systems

In recent years, wind power develops rapidly in our country. It is expected that installed capacity reach160～200million kw by2020. The characteristics of wind power system are tend to concentrated development and long-distance transmission. The problems of reactive compensation and voltage control are severe in large-scale wind power system. One of technical measures for solving this problem is installing controllable shunt reactor (CSR). In northwest of our country, one large-scale wind power system, which is conveying great power, far transmission distance, high voltage level, is building. In this system,750kV stepped controllable shunt reactor (SCSR) is firstly adopted in the world to compensate reactive power and control voltage. The author have been a trainee in China Electric Power Research Institute, and directly involved in research on control method of SCSR. This dissertation comes from actual project.Firstly, the voltage fluctuation in transmission lines of large-scale wind power system is expressed in the dissertation. The reactive power characteristics in large-scale wind power system are analyzed in detail. And conventional reactive compensation methods are introduced. Also the feasibility of SCSR in large-scale wind power system is analyzed.Secondly, example to the SCSR in one large-scale wind power system in our country is given, whose capacity is300Mvar and voltage is750kV (The SCSR include four steps, and three of them are adjustable). Its structure and working principle are analyzed. The simulation model is given, too. Control method of SCSR in steady-state is proposed, which is based on the bus voltage fluctuation of high voltage side in transformer substation. Also the influences of SCSR on power grid in transient state are proposed.Finally, simulation examples are carried out, which are based on an actual wind power project of our country. The relative study tools include PSD-BPA,EMTPE and MATLAB. The differences of voltage fluctuating are contrasted between SCSR and fixed capacity shunt reactor, also between SCSR switches and not switch. By analyzing and comparing these differences, the control method in this dissertation is demonstrated to be practical.