利用转子动能的风机辅助频率控制最优策略

Optimal Auxiliary Frequency Control Strategy of Wind Turbine Generator Utilizing Rotor Kinetic Energy

风机增加辅助频率控制模块是解决新能源取代同步机导致的电力系统频率安全问题的一种方案,其中利用转子动能的调频模式可以使风机运行在最大功率点,经济性比功率备用模式更好。已有研究主要让风机通过虚拟惯量和频率下垂控制模拟同步机,却未充分利用风机控制灵活、可塑性强的优点,且未考虑风机转子动能限制及系统频率二次跌落。论文跳出虚拟惯量加频率下垂控制的传统框架,提出利用转子动能的风机辅助频率控制最优策略。首先将风机输出功率曲线作为决策变量,通过优化得到最优功率曲线,然后设计对应的辅助频率控制策略,实现最优输出功率曲线。仿真结果验证所提策略的效果,并说明风机辅助频率控制不应局限于模拟同步机,而是有更优的策略。

Adding auxiliary frequency control module to the wind turbine generator(WTG) is a solution to the power system frequency security problem caused by the replacement of synchronous generator(SG) by the new energy. The frequency modulation mode using rotor kinetic energy can make the WTG operate at the maximum power point and obtain better economic gain than the power reserve mode. However, the flexibility of WTG output control are not fully utilized. The kinetic energy limit of the rotor and the secondary drop of system frequency are not considered. This paper broke through the traditional framework of virtual inertia and droop control. The optimal strategy of the WTG auxiliary frequency control based on rotor kinetic energy was proposed. Firstly, the WTG output power curve was taken as the decision variable, and the optimal power curve was obtained through optimization. Then, the corresponding auxiliary frequency control strategy was designed to achieve the optimal output power curve. The simulations verify the effectiveness of the proposed strategy, and show that the auxiliary frequency control of the WTG should have better strategies instead of being limited to the simulation of the SG.