一种电流突变量选相元件三相短路判据的探讨

Discussion of three-phase short-circuit criterion of phase selection relay based on delta variable element of phase current differential

在详细分析相电流差突变量选相基本原理的基础上,对传统相电流差突变量选相元件三相短路故障判据进行了改进。改进后的判据克服了原判据在实际系统发生三相短路故障时过于严格而产生误判的缺点,较好地解决了三相短路故障的误判问题,具有实现简单、灵敏的优点。以一典型500kV系统为例,运用EMTP(ElectroMagneticTransientsProgram)进行数字仿真形成故障数据文件,并在VC环境中编制选相程序,对改进后的三相短路故障判据和传统判据进行了比较测试,测试结果证明了该判据的正确性和有效性。

Based on the detailed analysis of basic criterion of phase selection element based on principle,the traditional three-phase short-circuit sudden-change of phase current differential is improved. The traditional three-phase short-circuit criteria are too strict to be met on site. The improved criteria are sensitive and simple in site implementation,avoiding the misjudgement of three -phase short-circuit fault. With a typical power system of 500 kV as an example,a comparative test is carried out using EMTP（Electro Magnetic Transients Program） digital simulation and test results show that the improved criteria is valid and effective.