考虑不对称故障影响的多馈入直流系统换相失败快速判别方法

Fast Detection Method of Commutation Failure in Multi Infeed DC System Considering the Effect of Unbalanced Fault

多直流馈入系统中直流输电的动态特性对系统整体稳定性的影响成为突出问题。提高交流系统不对称故障时直流准稳态模型对换相失败情况识别的准确度,对于提高系统分析精度具有重要意义。该文从逆变器换流阀的换流方程出发,考虑不对称故障时负序电压分量对换相电压角度偏移的影响,提出一种换相失败风险的快速识别判据。该判据在目前的高压直流准稳态模型基础上稍加修改即可实现。通过与机电–电磁混合仿真结果的比较,验证了文中方法的准确性与有效性。

The dynamic characteristics of HVDC transmission have a serious impact on the overall power system stability, and that has become the most severe challenge in the multi infeed DC system. The correct identification of commutation failure when unbalanced faults occurred in AC system is of great significance, especially in the stability transient simulation with a quasi steady state DC model. This paper proposed a fast identification criterion to access commutation failure risk, based on the commutation equation of inverter valve, considering the effect of negative sequence voltage components on commutation voltage angle offset during unbalanced fault. The criterion can easily be used in the current HVDC quasi steady state model. The accuracy and effectiveness of the proposed method were verified by comparison withthe results of electromechanical and electromagnetic hybrid simulation.