双馈风电机组变系数虚拟惯量优化控制

Optimal Variable-coefficient Virtual Inertia Control for DFIG-based Wind Turbines

传统的变速恒频风力发电机采用电力电子变流器控制,导致机组输出功率与系统频率解耦,使风力机无法响应系统频率变化,降低了系统转动惯量,在分析双馈风力发电机运行特性和虚拟惯量特性的基础上,研究了双馈风力发电机采用虚拟惯量控制的机组转速变化与输出功率的关系,提出了同时考虑调频效益和调频成本的变系数虚拟惯量控制策略。该控制策略分别以调频时双馈风电机组输出功率、转速恢复时间衡量调频效益、调频成本的大小,并采用遗传算法离线计算机组不同运行状态下的调频系数曲线和机组转速变化程度的最优值,以实现机组频率控制系数随机组转速变化而改变。根据计算所得调频系数曲线在MATLAB/Simulink软件平台进行仿真实验,结果表明所提方法能够使双馈风电机组在不同运行状态下响应系统频率变化,并保证机组自身稳定运行。

The traditional variable-speed constant-frequency(VSCF)wind power generator is controlled by the power electronic converter,which causes the active power of the wind turbine to be decoupled from the system frequency.Therefore,the wind power generator cannot respond to frequency changes and the moment of inertia of power system may decrease.Based on the analysis of the operation characteristics and virtual inertia characteristics of the doubly-fed induction generator(DFIG),the relationship between the change of speed and the active power of the DFIG-based wind turbine using virtual inertia control is studied.A variable-coefficient virtual inertia control strategy considering both the frequency regulation efficiency and frequency regulation cost is proposed.In this control strategy,the output active power and speed recovery time of DFIG-based wind turbines are used to measure the efficiency and cost of the frequency regulation.The genetic algorithm is used to calculate the optimal frequency regulation coefficient curve and the rotational speed deviation under different states of the wind turbine,so as to realize the frequency control coefficient changes with the variation of the rotor speed.According to the calculated coefficient curve,the simulation is carried out on the MATLAB/Simulink platform.The results show that the proposed method can respond to the system frequency changes under different operation conditions and ensure the stable operation of the DFIG-based wind turbine itself.