基于相电压差值极性的配电网单相接地故障检测方法

Single-phase grounding fault detection method for a distribution network based on phase voltage difference polarity value

针对现有配电网自动化设备和方法难以快速准确检测线路单相接地故障的问题,提出一种基于相电压差值极性的配电网单相接地故障检测方法。通过分析配电网线路单相接地故障时的电压幅值特征,考虑中性点不接地系统和中性点经消弧线圈接地系统的区别,揭示线路单相接地故障时故障相与非故障相的电压幅值关系。利用故障相与非故障相的电压幅值特性,定义线路的电压差值极性系数Q,建立相应的单相接地故障检测判据,实现线路单相接地故障的快速检测。仿真结果表明,所提方法能够有效检测线路单相接地故障,检测结果不受中性点接地方式、负荷波动和故障角度的影响,具有较好的抗高阻故障能力。现场试验表明,所提方法可在3 ms内检测线路是否发生单相接地故障,可有效检测2.5 kΩ过渡电阻的单相接地故障,具有较好的工程适用性。

There are shortcomings in the existing distribution network automation equipment and methods,in that they find it difficult to quickly and accurately detect single-phase grounding fault of lines.Thus a single-phase grounding fault detection method for a distribution network based on phase voltage difference polarity value is proposed.By analyzing the voltage amplitude characteristics of the single-phase ground fault for a neutral point ungrounding system and the neutral point through the arc suppression coil grounding system,the voltage amplitude relationship between the fault phase and the non-fault phase is obtained.From the voltage amplitude law of fault phase and non-fault phase,the voltage difference polarity valueQ is defined.The corresponding single-phase grounding fault detection criterion is established to realize the rapid detection of a single-phase grounding fault of the line.Simulation results show that the proposed method can effectively detect the single-phase grounding fault of the line,and the detection results are not affected by the neutral point grounding mode,load fluctuation and fault angle.It also has good resistance to high-impedance faults.Field tests show that the proposed method can detect single-phase grounding faults within 3 ms,and can effectively detect the single-phase grounding fault with a 2.5 k©resistance.This has good engineering applicability.