一种适用于同杆四回线单相接地距离保护的新算法

针对传统的距离保护直接应用于同杆四回线时易受零序互感的影响,使其测量阻抗精度达不到要求,从而造成保护继电器的误动或拒动,提出了一种单相接地距离保护新算法,利用12序分量法对同杆四回线进行参数解耦,结合同杆四回线单相接地故障模型,推导出保护安装处与故障点相电压之间的关系。在此基础上,根据接地故障时故障电压与故障分支电流间相角关系,分析了故障位置的零序电流与保护安装处的零序电流之间的关系式,并代入故障位置计算,从而消除故障电压对其算法的影响。大量的PSCAD/EMTDC仿真结果表明,该保护在各种单相接地情况下均具有较高灵敏度及可靠性。

New Algorithm for Single-phase Grounding Distance Protection of Four-parallel Transmission Lines

Application of traditional distance relay to four-parallel transmission lines is adversely affected by the mutual coupling between the lines. The result will lead to not achieve measured impedance calculation. And it has impact on the operation of ground protection. In this paper, a new ground distance algorithm is proposed for single-phase grounding fault of four-parallel transmission lines. Based on the case of single-phase grounding fault, the relationship between fault point voltage and the voltage at protection installed location is presented by twelve-sequence component method. According to the relationship of phase corner between the fault voltage and the fault current, the relationship between the zero-sequence current of the fault location and zero sequence current protection installed at the location is analyzed. And then putting them into the fault location, the impact of fault voltage is eliminated. The simulation results of PSCAD/EMTDC show that the new scheme has high sensitivity and reliability under different single-phase grounding fault of four-parallel transmission lines.