基于虚拟能量变化率的谐振接地系统高阻接地故障选线方法

谐振接地系统的高阻接地故障由于消弧线圈和接地阻抗作用,故障电气量较微弱,故障检测与选线困难。通过对高阻故障的暂稳态特征以及故障线路对地支路的瞬时和永久性改变的分析,总结出健全线路和故障线路对地电容参数的瞬时变化规律及特征。进而构造表征故障前后各线路对地电容参数变化的虚拟能量分量,并分析虚拟能量变化率的变化规律。最后,提出了利用线路虚拟能量变化率峰值占比来确定故障线路的判据,并用于设计故障选线方法。所述方法在保证选线正确的同时,扩大了检测范围并增强了抗三相不平衡干扰的能力,仿真结果和现场实测数据验证了方法的准确性与可靠性。

Fault Line Selection Method for High-Impedance Grounding Fault of Resonant Grounded System Based on Change Rate of Virtual Energy

Due to the effect of the arc suppression coil and the grounding impedance,the electrical quantity of the high-impedance grounding fault in the resonant grounded system is relatively weak,which makes fault detection and line selection difficult.Through the analysis of the transient and steady state characteristics of high-impedance faults and the instantaneous and permanent changes of the fault line to the ground branch,the rules and characteristics of the instantaneous change of line-to-ground capacitance parameters of the normal line and the fault line are summarized.Furthermore,this paper constructs the virtual energy component that characterizes the change of line-to-ground capacitance parameters of each line before and after the fault,and analyzes the change law of change rate of virtual energy.Finally,the criterion of using the peak ratio of the virtual energy change rate of the line to determine the fault line is proposed and used in the design of the fault line selection method.The method not only ensures the correct line selection,but also improves the detection range and the ability to resist three-phase imbalance interference.Simulation results and field measured data verify the accuracy and reliability of this method.