一种超高压输电线路自适应分相电流差动保护新原理研究

Study on new principle of adaptive current differential protection for EHV transmission line

根据分相电流差动保护的基本判据,分析线路两端电流量幅值和相位对保护动作特性的影响,提出一种制动系数自适应于线路两端电流量幅值之比的分相电流差动保护新原理。按照穿越性电流对差动保护进行制动的传统方法忽略了线路两端电流量幅值之比对保护动作特性的影响,新原理则充分考虑了这一影响。理论分析和动模试验数据表明,采用该新原理可以增加分相电流差动保护抗电流互感器饱和能力,有效提高保护反映区内、外故障的总体性能。

According to the basic criteria,the influence of the amplitude and phase of terminal currents on the sensitivity and reliability of conventional phase-segregated current differential protection is analyzed. A new principle of phase - segregated current differential protection is put forward. It has adaptive restraint coefficient corresponding to the amplitude ratio of terminal currents,which is neglected in the conventional approach with the restraint current derived from the current through the line. The results of theoretical analysis and dynamic simulation tests show that the ability against the influence of CT saturation is improved and its general performance in response to both internal and external faults of the protected transmission line is effectively enhanced.