Study on the frequency control method and AGC model of wind power integration based on the full dynamic process simulation program

Abstract

Wind power is a random and intermittent energy source, wind farm output prediction accuracy is not yet able to meet the purpose of engineering applications. In recent years, with the large-scale wind power integration, because of the randomness and volatility of wind power output, the active power of system node fluctuates severely, which greatly increases the difficulties in controlling the grid system frequency. The frequency regulation with wind power not only involves the primary frequency control in short time of second range, but also the secondary frequency control in long time of minute range[1]. It requires the simulation program can not only simulate the regulation of plant governor, but also can simulate combined regulation of the power plant thermal system and hydraulic system, furthermore the simulation time spans from the second level to 10 ∼ 15 minutes. China Electric Power Research Institute developed the full dynamic simulation program( FDS), which combines electromagnetic transient process, the electromechanical transient process, with mid-long-term dynamic process perfectly. The simulation time can be up to dozens of minutes. Consist of the governor model, the boiler model, hydraulic system model and AGC model and so on, FDS can simulate the full dynamic process of power system after big disturbances, and provides the analysis tool for the frequency study on the large-scale wind power integration. This paper is based on AGC model of full dynamic simulation program, mainly aiming at the governor related to the primary frequency control, the main frequency regulation units related to the secondary frequency control, the measured parameters of boiler, turbine and generator controlled by AGC, as well as restrained by AGC control and generating unit ramp rate. The fluctuations of wind farm output power is equivalent as the fluctuations of negative load[2]. This model controls the output of conventional generator to achieve the frequency requirements of wind power integration. At last, a 3-generator 10-node system, which wind power capacity accounts for 5.2% of the entire system, is set up by FDS. The simulation results show that, in the normal operation conditions, AGC can effectively reduce the frequency fluctuation brought by wind power integration.