谐振接地系统高阻接地故障暂态能量分析与选线

Transient Energy Analysis and Faulty Feeder Identification Method of High Impedance Fault in the Resonant Grounding System

配电线路高阻接地故障时有发生,传统小电流接地故障暂态无功功率方向保护方法不再适用。该文利用谐振接地系统高阻接地故障等值电路,分析故障后系统对地电容与消弧线圈存储的暂态能量以及各线路实际测量的暂态能量随时间的变化规律,发现：健全线路测量的暂态能量是本线路对地电容释放的能量,等于电容在接地时刻的暂态初始能量;故障线路测量的暂态能量是故障点过渡电阻吸收的能量,等于所有健全线路对地电容和消弧线圈在接地时刻的暂态初始能量之和。可选择暂态能量由母线流出的线路为故障线路。该文的工作完善了小电流接地故障暂态理论分析,提高高阻接地故障选线正确率,算法有自具性。仿真和现场数据验证理论分析与选线算法是正确可行的。

High impedance fault occurs frequently in distribution feeders. The conventional transient reactive power direction protection method for single-phase earth fault in non-solidly earthed network fails to work in high impedance fault of the resonant grounding system. By using the equivalent circuit of the resonant grounding system, the changing rule of the post-faulty transient energy stored in the system capacitance to ground and the Petersen coil as well as the post-faulty measured transient energy of all feeders were analyzed. The measured transient energy of the healthy feeder is the energy released by the feeder＇s capacitance to ground, which is equal to the capacitance＇s transient initial energy. The measured transient energy of the faulty feeder is the energy absorbed by the transition resistance, which is equal to the sum of transient initial energy of all the healthy feeders＇ capacitance to the ground and the Petersen coil. The faulty feeder is the feeder whose transient energy flows out of the bus. In this paper, the transient theoretical analysis of single-phase earth fault in non-solidly network was improved, the accuracy of the faulty feeder identification in high impedance fault was increased, and the algorithm was proved to be self-containing. The accuracy and feasibility of the theoretical analysis and novel method were verified by simulation.