基于暂态零序电流凹凸特征的配电网故障区段定位方法

为保证系统安全运行,不改变原系统中性点小电流接地方式,DG中性点一般采用不接地。当主网发生单相接地故障时DG不向系统提供零序电流,故不影响暂态零序电流故障特征。进一步对暂态零序电流波形特征进行分析发现,其凹凸特点包含着可用于定位的故障信息。采用VMD算法来提取能够表征暂态零序电流凹凸特征的有效成分,并提出波峰波谷算法对有效频率分量的凹凸特性进行刻画。根据故障点两侧凹凸数相差较大且初始凹凸性相反,而故障点同侧其凹凸数大致相等且初始凹凸性相同的特征,构造了基于峭度和初始凹凸性故障定位判据。通过将各区段峭度差值与设定阈值比较并判断初始凹凸性是否一致,从而定位故障区段。仿真试验表明,该方法能够适用于有源配电网故障定位,且在不同故障情况下具有较强的适用性。

Fault section location method for a distribution network based on concave and convex characteristics of transient zero sequence current

In order to ensure the safe operation of a system and not change the small current grounding mode of the original system neutral point, the DG neutral point is generally ungrounded. When a single-phase ground fault occurs in the main network, DG does not provide zero sequence current to the system, so it does not affect the fault characteristics of the transient zero sequence current. Further analysis of the waveform characteristics of the transient zero sequence current shows that the concave convex characteristics contain fault information that can be used for location. In this paper, the VMD algorithm is used to extract the effective components. These can represent the concave convex characteristics of the transient zero sequence current, and a wave peak valley algorithm is proposed to describe the concave convex characteristics of the effective frequency components. Given that the concave convex numbers on both sides of the fault point are quite different and the initial concave convex is opposite, while the concave convex numbers on the same side of the fault point are roughly the same and the initial concave convex are the same, a new algorithm based on the kurtosis and the initial concave convex is constructed. By comparing the kurtosis difference of each section with the set threshold and judging whether the initial bump is consistent, the fault section can be located. The simulation results show that the method can be applied to the fault location on an active distribution network, and has strong applicability in different fault situations. This work is supported by National Natural Science Foundation of China (No. U1766204).