为解决目前带串补线路的距离保护可靠性和灵敏性不足的问题,提出一种基于频域模型识别的带串补线路的距离保护方案。利用最小二乘矩阵束方法,准确获取电力系统故障暂态过程中各频点的电压电流相量,通过列写基于分布参数的输电线路端口电压方程,构建串补输电线路全频带模型误差函数。利用全频带误差模型和工频量故障定位结果,识别故障点相对于串补电容的位置,若故障位于串补电容前,则直接驱动断路器跳闸;若故障位于串补电容后,则根据传统的电平检测逻辑动作。该方法仅利用单端量电气量,不受串补电容器和金属氧化物限压器(metal oxide varistor,MOV)(或称限压电阻)的影响,提高了串补输电线路单端量保护的性能。仿真结果验证了该方法的有效性和实用性。
A model identification-based distance protection scheme is proposed in this paper to improve the reliability and sensitivity of the relay protection for series compensated transmission lines.The current and voltage phasors were obtained firstly by using the least squares matrix pencil method which could accurately calculate phasors at each frequency even in transient conditions.Then,based on distributed parameter model of transmission lines and fundamental frequency-based fault location method,a model error function in frequency domain was defined to identify faults in front of the series capacitor from those behind the series capacitor.By utilizing model error identification and conventional distance protection scheme,a novel distance protection scheme was designed for series compensated transmission lines.If a fault takes place in front of the series capacitor,the circuit breaker would be tripped directly.If the fault takes place behind the series capacitor,the circuit breaker would be tripped according to the voltage of the series capacitor.The proposed scheme can improve the performance of the protection for series compensated transmission lines due to its immunity to the influences of series capacitor and metal oxide varistor(MOV).Simulation results verified the validity of the proposed distance protection scheme.