基于定关断面积的混合双馈入直流输电系统换相失败抑制策略

A Constant Extinction Area Based Control Strategy for Suppressing Commutation Failure in Hybrid Dual-Infeed HVDC System

为充分发挥电压源型换流器高压直流输电（voltage source converter high voltage direct current,VSC-HVDC）对交流系统无功支撑的作用,抑制电网换相换流器高压直流输电（line-commutatedconverterhighvoltagedirectcurrent,LCC-HVDC）换相失败的发生,提出了一种基于定关断面积的混合双馈入直流输电系统换相失败抑制策略。基于定关断面积得出交流电压补偿值,附加至VSC-HVDC逆变器外环无功控制环节,提升故障发生后VSC-HVDC对受端交流系统的无功支撑能力;增加VSC-HVDC动态功率限幅调节控制,优先保证无功功率的传输,同时尽可能减少有功功率的降幅。基于PSCAD/EMTDC进行了仿真分析,仿真结果证明了该控制策略可显著提升LCC-HVDC抵御换相失败的能力,且有效减少直流系统传输功率的降幅。

In order to take full advantage of the ability of voltage source converter high voltage direct current（VSC-HVDC） to support reactive power of ac system, and suppress commutation failures of line-commutated converter high voltage direct current（LCC-HVDC）, this paper proposes a constant extinction area based control strategy for suppressing commutation failure in hybrid dual-infeed HVDC system. AC voltage compensation is derived based on the constant extinction area, and added to reactive power control of outer loop improving reactive power support ability of VSC-HVDC. Dynamic power limit regulation is put forward to ensure the priority of reactive power transmission, and reduce amplitude decrease of active power as far as possible. Simulation result obtained in PSCAD/EMTDC shows that the proposed strategy can effectively improve the ability of LCC-HVDC to suppress commutation failures, and lower DC power reduction.