考虑电容电流的同塔双回线接地距离保护零序电流补偿系数的整定

分析了同塔双回线路在独立运行方式下零序互感和电容电流2种因素对零序电流补偿系数的影响.推导了接地距离保护的数学模型,在传统接地距离保护基础上,提出一种零序电流补偿系数整定新方法,即零序电流补偿系数为原始零序电流补偿系数、附加零序互感补偿系数与附加电容电流补偿系数之和,给出了零序电流补偿系数计算公式. PSCAD仿真结果表明,整定范围为线路80%时,线路末端故障情况下,所提方法比传统方法更能准确地反映故障位置,且能使两侧的距离 I 段保护范围有交叉,提高了同塔双回线路的距离保护性能

Setting of Zero-Sequence Current Compensation Coefficient for Ground Distance Relays of Double-Circuit Transmission Lines on Same Tower Considering Capacitive Current

The influences of zero-sequence mutual inductance between the two circuits and capacitive current on zero-sequence current compensation coefficient were analyzed while the two circuits of double circuit transmission lines on the same tower are operated independently.A mathematical model of ground distance protection was derived,and based on traditional ground distance protection a new method to set zero-sequence current compensation coefficient was proposed,i.e.,the zero-sequence current compensation coefficient was regarded as the sum of original zero-sequence current compensation coefficient,additional zero-sequence current compensation coefficient and additional capacitive current compensation coefficient,meanwhile the computing formulae of the three zero-sequence current compensation coefficients were given.Results of PSCAD-based simulation showed that when the setting range was eighty percent of total length of the transmission line and the fault occurred at the end of the transmission line,the fault position could be reflected by the proposed method more precisely than by traditional methods,besides,the first zones within the protection regions measured from both ends of the transmission line could be overlapped,thus the performance of ground distance protection for double-circuit transmission lines on the same tower could be improved.