故障分量方向元件的电容电流补偿方案

Compensation scheme of capacitance current for fault components based directional elements

提出一种电容电流按比例补偿方案,解决环网中故障分量方向纵联保护误动的问题。比较线路两端故障分量电流幅值确定各自补偿比例,采用线路分布参数T模型计算电容电流补偿总量,结合补偿比例和补偿电流总量可以得到线路两侧各自的补偿电流值,并进而求得补偿后的电流量。理论分析及数字仿真表明,利用补偿后的电流量构造故障分量方向元件,能够有效防止环网中线路区外故障两侧正方向元件同时启动导致纵联保护误动的问题,对于仅一端正方向元件启动的情况也能适当提高保护安全性,而对于区内故障补偿产生的影响基本可以忽略。

A proportional compensation scheme of capacitance current was proposed to prevent the mal-operation of the transmission line pilot protection based on fault component directional elements in a loop network. Firstly, the compen- sation ratios of the both ends of lines were confirmed according to the amplitudes of fault component current. Then the gross compensation values of capacitance current were computed by use of the T model which is formed by line distribu- ted parameters. On the basis of the above factors the compensation current and the compensated current of the both ends of lines were acquired. At last, theoretical analysis and numerical simulations demonstrated the suggested scheme can effectively prohibit the mal-operation of pilot protection when an external fault occurs in a loop network, which is resulted from the two terminal forward direction elements both act. Moreover, the protection security can be advanced in the situation that only one terminal forward direction element acts with an external fault. When an internal fault oc- curs, the influence of current compensation can be ignored.