基于转矩极限的改进风电机组虚拟惯量控制策略

IMPROVED VIRTUAL INERTIA CONTROL STRATEGY OF WIND TURBINE GENERATORS BASED ON TORQUE LIMIT

为解决大规模风电并网带来的系统频率稳定性降低问题,风电机组通过虚拟惯量控制可为系统提供短期频率支撑,然而惯性响应期间风电机组转速收敛缓慢,导致一部分转子动能被无故浪费;转速恢复阶段的有功突变易造成频率二次跌落。为此,提出基于转矩极限的改进风电机组虚拟惯量控制策略,实现在释放较少动能的前提下提供与传统策略相同的频率响应服务;并在频率步入准稳态时,借助时变功率函数开始转速恢复,实现转速快速恢复的同时缓解二次频率跌落。基于EMTP-RV仿真软件搭建包含风电场的电力系统模型,验证了所提策略的有效性。

To solve the issues of reduction of the system frequency stability caused by large-scale wind power integrations,the shortterm frequency support can be obtained for the wind turbine generators by using virtual inertia control. However,when performing virtual inertia control,the slow rotor speed convergence results in the unnecessary waste of the rotor kinetic energy. The sudden change of active power during the rotor speed recovery stage is prone to cause the second frequency drop(SFD). To this end,this paper proposes an improved virtual inertia control strategy of wind turbine generators based on torque limit. The proposed strategy can preserve the frequency nadir with the less released rotor energy;when the system frequency reaches to the quasi-steady state,the rotor speed recovery is started with time-varying power function so as to realize the rapid speed recovery while alleviating the SFD. The proposed virtual inertial control strategy is verified based on an electric power system model embed with a doubly-fed induction generator-based wind power plant using on EMTP-RV.