基于R-L模型的串补线路距离保护方案

针对串补线路故障特性更为复杂，造成距离保护难以正确动作的问题，提出了一种利用单端信息的串补线路故障测距方案。以R-L模型为基础，根据串补前及串补后故障线路参数的不同，给出了2个测距计算模型。利用该模型计算出的电阻值与实际电阻值的对比，可准确判断故障点相对串补装置的位置。若故障发生在串补装置前，则直接驱动断路器跳闸;若故障发生在串补装置后，则利用串补后的故障计算模型，判断出故障位置。该方法可以较好地解决传统距离保护在串补线路中的暂态超越问题，同时，利用MOV导通前的暂态信息，避开了MOV导通初期串补电容电压难以获取的问题，极大地提高了距离保护的可靠性。利用PSCAD仿真验证了该方案的可靠性和有效性。

A Distance Protection Scheme of Series Compensated Line Based on R-L Model

Since the failure characteristics of series compensated lines are more complicated, the distance protection is usually difficult to operate correctly. This paper investigated a new fault location algorithm based on one-terminal signals. This method is conducted by the R-L model of the transmission lines. According to the different fault parameters of the transmission line in front of or behind the series compensation device, two calculation models for distance measurement were presented. By comparing the calculated resistance values with the real values, the relative position of the fault can be located. If a fault takes place in front of the series capacitor, the circuit breaker would be tripped directly. But if the fault takes place behind the series capacitor, the fault location can be found by the presented model and the calculation algorithm mentioned above. This scheme can solve the transient overreach problem in traditional series compensated protection scheme. At the same time, this scheme uses the transient data only before the mental oxide varistor(MOV) conducting, the protection can avoid MOV’s nonlinearity which makes the voltage of series compensated capacitors not easy to obtain. By this method, the reliability of the distance protection can also be improved greatly. At the end, the validity and adaptability of the scheme were verified through the PSCAD simulation.