基于DFIG无功优化控制的直流换相失败暂态过电压抑制

Transient overvoltage suppression of DC commutation failure based on reactive power optimization control of doubly-fed induction generator

当高压直流系统发生换相失败时,送端电网电压呈现“先低后高”连续变化的特征,风电机组动态控制不佳,严重时会造成脱网。为克服传统国标控制策略未考虑电压连续变化特征下的控制“空白区”问题,揭示了换相失败暂态过电压的形成机理并分析了其暂态形态特性;在传统国标控制策略的基础上,引入无功电流系数细化电流指令并利用转子侧换流器进行优先分配,确定了基于双馈感应发电机(DFIG)无功优化的故障穿越控制策略。基于MATLAB/Simulink仿真平台对所提控制策略进行验证。结果表明相较于传统国标控制策略,所提控制策略能够进一步抑制换相失败恢复阶段的暂态过电压现象。

When the commutation failure of the high voltage direct current(HVDC)system occurs,the power grid voltage at the sending end shows the characteristics of continuous change of“low first and then high”,and the dynamic control of the wind turbine is poor,which will cause disconnection in serious cases.In order to overcome the control“blank area”under the existing national standard control strategy that does not consider the characteristics of continuous voltage change,the formation mechanism of commutation failure transient overvoltage is revealed and its transient characteristics are analyzed.On the basis of the existing national standard control strategy,the reactive current coefficient refinement current instruction is introduced and the rotor side converter is used for priority allocation,and the fault ride-through control strategy based on doubly-fed induction generator(DFIG)reactive power optimization is determined.The proposed control strategy is verified based on the MATLAB/Simulink simulation platform.The results show that the pro⁃posed control strategy can further suppress the transient overvoltage phenomenon in the commutation failure recovery stage compared with the traditional national standard control strategy.