输电线路微机距离保护中解微分方程算法的分析与改进

为改善基于单端电气量距离保护的性能,提高距离继电器承受过渡电阻的能力,从单端故障测距的角度出发,分析距离保护中计算阻抗的常用算法———解微分方程算法,结合输电线路发生各种故障后的电压电流关系,对传统的解微分方程算法进行了分析。根据分析得到的结果,对两相短路故障和两相接地短路故障算法进行了改进。针对传统的用于两相故障和两相接地故障中的解微分方程算法不能有效地克服负荷电流对于计算电抗的影响,在改进中重点解决如何有效消除负荷电流的影响。两相故障采用非故障相来消除负荷电流的影响,而两相接地故障则根据故障点电流和保护安装处零序电流的关系消除负荷电流影响。通过仿真计算表明,经改进的算法较常用算法抗过渡电阻能力强,测距结果比常用的解微分方程算法更准确,可应用于实际的距离保护装置中。

Analysis and Improvement of Algorithm for Solving Differential Equation in Computer Distance Protection of Transmission Line

For improving the quality of distance protection based on single end electric quantity and overcoming the transition resistance,from the point of view of fault location,the algorithm for solving differential equation is analyzed in computer distance protection.Considering the relation between voltage and current after fault occurred in every fault types,based on the result analysed,the algorithm is improved for solving differential equation used in the double phase fault and double phase grounded fault.Because the traditional algorithm can not overcome the influence of load current,how to overcome this influence is the emphasis.In the double phase fault,non-fault phase is used;in the double phase-ground fault,the relation between the fault current and the current is measured by protection equipment.Through the simulation,we can find the algorithm improved can overcome higher fault resistance and be used in the equipment for distance protection.