高压直流输电中阀短路保护的动作方程研究

Study on the Operational Equation for Valve Short Circuit Protections in HVDC Projects

作为高压直流输电系统中换流器的主保护,现有的阀短路保护主要有2类动作方程。这2类动作方程的动作函数和制动函数均存在一定的差异。通过分析阀短路保护测量的电流在各种换流器故障下的变化规律,对2类动作方程进行了对比分析。在此基础上,对其中的一类动作方程进行了改进,使其具备定位故障桥的功能。提出阀短路保护的分段式制动函数,较好地克服了保护的选择性和灵敏性之间的矛盾,并给出了相应的参数确定方法。以CIGRE直流输电标准测试系统为例,对区内所有短路故障和区外一些短路故障进行测试,验证了该文对2种动作方程理论分析的正确性和制动函数中参数确定方法的合理性。

As the primary protection for high voltage direct current （HVDC） converters, there are two kinds of typical operational equations for valve short circuit protections. Differences between the two kinds of operation equations were studied. Based on analyzing the characteristics of the currents under various converter faults, the performances of the two operational equations were compared. Furthermore, one of the operational equations was revised to have the function of locating faulty bridge. To coordinate the contradiction requirements of selectivity and sensitivity in protection settings, a setting function was proposed according to the analysis of existent setting functions. Then the protection setting method was described. The short-circuit faults in the converter and some outside the converter were tested with CIGRE HVDC Benchmark Model and the validity of the theoretical analysis was verified.