Research On Active Power Optimal Control In Wind Farms Considering Frequency Regulation Demand

With the continuous increase of the wind power capacity integrated to the grid, a series of challenges are brought to the power grid. Due to the shortage of conventional generation reserve for frequency regulation, the frequency events and peak shaving problems of power system are becoming increasingly prominent. On the other hand, large wind power capacity integrated to the grid that could not be consumptive effectively, leads to massive wind power curtailment. It is necessary for wind farms to possess the ability of active power control(APC) and primary frequency control(PRC) similar to conventional power plants.This paper focus on the ability of APC and PRC of wind farms under wind power curtailment condition, and a de-load control scheme is proposed to reserve part power capacity of wind turbines so that wind farms can dispatch wind turbines flexibly to satisfy the demand of power grid and participate in the frequency regulation of power system. Firstly, wind turbines are classified into three categories according to their wind speed, then a specific de-load control strategy that coordinates over-speed control and pitch angel control based on wind speed condition is put forward, which could take advantage of both over-speed control and pitch angel control. Simulation results under different situations validate the correctness and validity of this strategy.After wind farms have the ability to reserve part wind power which can be used as frequency reserve, a method is come up with to calculate the droop value of WTGs according to the operating condition of wind farms. Wind farms can support the frequency regulation as much as possible under output restricted condition combined with the droop value calculation method and the active power dispatch strategy of wind farms that coordinates limited load demand and frequency control requirement.In the end, a primary frequency simulation model that consists of a conventional power plant and a wind farm is built in Matlab/Simulink. Simulation results show that the proposed de-load control scheme and frequency control strategy could meet the comprehensive demand of the power system, improve the performance of PFC, alleviate the frequency regulation pressure of conventional power plants, and make full use of reserve wind energy.