基于时域电容电流补偿的电流差动保护研究

针对超、特高压输电线电流差动保护受暂态电容电流影响,以及基于贝瑞隆线路模型法的差动保护中采样频率和输电线路长度难以配合的问题,提出了基于Π形等值电路的时域电容电流补偿的差动保护.所提出的差动保护是利用微分方程模型对瞬时值进行补偿,能够有效地消除暂态和工频稳态电容电流的影响,解决了常规工频相量补偿法仅能补偿稳态电容电流且计算数据窗较长的缺陷.仿真结果表明,该差动保护适合应用5 ms数据窗的小矢量算法,提高了保护动作速度,而不需要提高采样频率,不增加计算量和通信量,采取低通滤波措施后可以提高时域电容电流补偿的效果.

Current Differential Protection Based on Time-Domain Algorithm of Capacitive Current Compensating

The current differential protection of ultra high voltage transmission lines is affected by transient capacitive current, and it is difficult to match the sampling frequency to the length of transmission lines in a differential relay in Bergeron transmission lines model. Aiming at the mentioned problems, a novel current differential protection scheme based on time-domain compensating algorithm with II equivalent circuit is proposed. Evaluating the instantaneous value of differential equation model, the proposed algorithm enables to effectively eliminate the adverse influence caused from both transient and stable distributed capacitive current, and to break through the limitation of conventional phasor compensating algorithms, where only stable capacitive current can be compensated with a long data-window. The simulation results show that it is unnecessary to augment the sampling rate, mathematical operations and the telecommunication traffic, the phaselet algorithm with data in 5 ms is suitable for the proposed protection, and the effects of time-domain capacitive current compensating algorithm can be improved with lowpass.