基于小波包分解的小电阻接地系统高阻接地故障检测方法  

Detection Method of High Impedance Fault in Small Resistance Grounding System Based on Wavelet Packet Decomposition

作　　者：田凤兰 唐琪 马瑾 徐铭铭 邹会权 李景丽[4] 袁豪 任俊跃 TIAN Fenglan;TANG Qi;MA Jin;XU Mingming;ZOU Huiquan;LI Jingli;YUAN Hao;REN Junyue(Zhengzhou Power Supply Company of State Grid Henan Electric Power Company,Zhengzhou 450052,China;Electric Power Research Institute of State Grid Henan Electric Power Company,Zhengzhou 450052,China;HenanJiuyu Enpai Power Technology Co.,Ltd.,Zhengzhou 450052,China;School of Electrical Engineering Zhengzhou University,Zhengzhou 450001,China)

机构地区：[1]国网河南省电力公司郑州供电公司,郑州450052 [2]国网河南省电力公司电力科学研究院,郑州450052 [3]河南九域恩湃电力技术有限公司,郑州450052 [4]郑州大学电气工程学院,郑州450001

出　　处：《电瓷避雷器》2023年第1期179-190,共12页Insulators and Surge Arresters

摘　　要：小电阻接地系统发生高阻接地故障时电流小于传统的零序电流保护动作阈值,并且时常伴随有电弧的发生,难以准确检测与切除高阻接地故障。文章首先分析了小电阻接地系统发生单相高阻接地故障时母线零序电压与线路零序电流的稳态特征以及接地故障电流的暂态特性。其次,针对高阻接地故障常伴随的电弧现象,对Schwarz电弧模型引入电弧长度加以改进,将改进的Schwarz模型与Mayr模型、Schwarz模型、“控制论”模型对比,分析表明所提电弧模型具有一定的合理性;并搭建了电容电流达158 A的10 kV小电阻接地方式配网模型,更加贴合实际配网。然后利用Coiflet4对母线零序电压和线路零序电流进行5层小波包分解,分析发现故障线路零序电流分解系数的极性与母线零序电压分解系数的极性相反且大于非故障线路零序电流分解系数。最后设置不同过渡电阻直接接地、不同过渡电阻经改进的Schwarz电弧模型串联接地、不同故障距离及不同故障相角等故障条件,验证了所提检测方法的可靠性。When high impedance fault occurs in small-resistance grounding system, the current is less than the traditional zero-sequence current protection action threshold, and it is often accompanied by the occurrence of arcs, so it is difficult to accurately detect and remove the high impedance fault. The author firstly analyzes the steady-state characteristics of busbar zero-sequence voltage and line zero-sequence current and the transient characteristics of grounding fault current when single-phase high-resistance grounding fault occurs in small-resistance grounding system. Secondly, according to the arc phenomenon often accompanied by high impedance faults, the arc length introduced into the Schwarz arc model is improved. The improved Schwarz model is compared with Mayr model, Schwarz model, and cybernetic model. The analysis shows that the proposed arc model has certain rationality. A 10 kV small-resistance grounding distribution network model with capacitor current of 158A is built, which is more in line with the actual distribution network. Then, Coiflet4 is used to decompose the bus zero-sequence voltage and line zero-sequence current by 5-layer wavelet packet decomposition. The analysis shows that the polarity of the zero-sequence current decomposition coefficient of the faulty line is opposite to that of the bus zero-sequence voltage decomposition coefficient, and it is larger than that of the non-faulted line. Finally, the reliability of the proposed detection method is verified by setting the fault conditions such as direct grounding of different transition resistances, series grounding of the improved Schwarz arc model of different transition resistances, different fault distances and different fault phase angles.

关 键 词：高阻接地故障 小波包分解 电弧模型 零序电流 

分 类 号：TM862[电气工程—高电压与绝缘技术]