结合超速备用和模拟惯性的双馈风机频率控制策略

Integrated Frequency Control Strategy of DFIGs Based on Virtual Inertia and Over-Speed Control

基于双馈风机的风电场大规模并网将导致电网等效惯量降低、一次调频能力不足。为了使双馈风机同时具备惯性调频和一次调频能力,并解决传统模拟惯性控制方法容易引起的二次频率冲击问题,提出了一种结合超速备用和模拟惯性的双馈风机有功频率控制策略。双馈风机在电网频率正常时运行在超速减载状态,获得一定的调频备用容量并提高转子存储动能;在系统频率变化时,通过检测电网频率偏差、调节参考转速来改变输出功率,参与系统调频。该策略可以使双馈风机具有和常规机组类似的静态调频特性,能有效支持系统的惯性调频,减小静态频率误差,并避免转速恢复对系统频率的二次冲击。最后通过仿真验证了所提控制策略的有效性。

Large scale integration of DFIGs-based wind farms in power system would reduce system equivalent inertia and capability of primary frequency control. To enhance DFIG frequency control ability and avoid secondary frequency drop, this paper presents a new frequency control strategy based on combination of virtual inertia and over-speed control. DFIGs work at higher speed using over-speed control to store more kinetic energy and gain reserve capacity, and their active power output can be changed with virtual inertia control to respond frequency deviation after system disturbance. Using this proposed method, DFIGs achieve frequency regulation performance similar to that of synchronous generators, providing effective inertia support and certain reserved capacity and reducing risk of secondary frequency drop. Simulations performed verified validity of the proposed method.