消除STATCOM对线路距离保护影响方法的研究

Research of a new method of eliminating the effect of STATCOM on distance protection

从理论上分析了STATCOM对距离保护测量阻抗的影响,STATCOM的装设使测量阻抗中产生了一个附加阻抗,会使阻抗继电器出现欠范围拒动和超越动作的行为。建立了包含STATCOM的双机保护系统模型,并对不同故障类型和不同补偿度时距离保护的误动进行了仿真,结果表明STATCOM的补偿度越高,距离保护发生误动的情况越严重。根据故障时保护安装处电压幅值的大小与故障点的位置远近有关,提出了故障位置识别的判据及消除距离保护误动的方案,通过判断故障回路是否包含STATCOM而自适应的调整测量阻抗,若故障回路中包含STATCOM,则在原测量阻抗的基础上减去附加阻抗,再与定值进行比较,否则将测量阻抗直接与定值进行比较。对各种故障情况进行仿真验证,结果表明所提方法可以有效地消除距离保护的误动,提高保护的可靠性。

This paper theoretically analyses the impact of the STATCOM on the measured impedance of distance protection. The installation of the STATCOM will produce an additional impedance in the measured impedance. This phenomenon will make the impedance relay under-reaching or over-reaching. A two-generator protect system model with STATCOM is established and the maloperation of distance protection in different fault types and different compensated degree is simulated. Results prove that the higher the compensated degree of STATCOM is, the more serious the effect is. According to that the voltage amplitude of protection at fault is related to the location of fault point, it proposes a criterion of fault point identification and scheme of eliminating the fault action of distance protection. We can judge that whether the fault circuit contains STATCOM, if it contains STATCOM, the actual fault impedance is the original measured impedance minus an additional impedance, and then compare it with definite value; on the contrary, the measured impedance is directly compared with the definite value. Simulations have been made to verify the correctness and the feasibility of this new method. Results prove that the proposed method can effectively eliminate the fault action of distance protection and improve the reliability of the protection.