电工技术学报2024，Vol.39Issue(23)：7418-7429,12.DOI:10.19595/j.cnki.1000-6753.tces.231742
基于相位差的小电阻接地有源配电网接地故障保护算法
Grounding Fault Protection Algorithm of Small Resistance Earthing Active Distribution Network Based on Phase Difference
摘要
Abstract
After the large scale distributed power supply is connected to the distribution network of the small resistance grounding system,the fault current changes significantly,which affects the original grounding protection accuracy of the system,zero-sequence current protection method is used to remove the single-phase ground fault.In recent years,experts and scholars have put forward the zero-order current phase differential protection scheme,pearson correlation protection method and zero-sequence current centralized comparison method,which is necessary to collect the zero-order current amplitude or phase of different monitoring points to upload it to the main station to calculate the fault location,which depends highly on communication and main station algorithm.In order to solve the above problems,the grounding fault protection algorithm of small resistance grounding system based on phase voltage and zero sequence current is proposed. By establishing the structure and model of the distribution network grounding fault electrical system containing multiple distributed power sources,we theoretically derive and calculate the phase voltage and zero sequence current at the time of failure,by calculating the phase difference between different grounding fault positions and different grounding transition resistances.Analyzing the phase difference interval characteristic value of ground boundary fault,outboundary fault and DG outboundary fault,according to the interval eigenvalue,the protection algorithm is implemented by:Real-time acquisition and calculation of zero-order current amplitude,when its effective value is 3In＞Iset,start the protection calculation;real-time acquisition and calculating phase voltage amplitude,compare the three-phase voltage amplitude,select the phase with the amplitude drop as the fault phase;calculate the phase difference between the fault phase voltage and the zero-order current in real time,when the phase difference θUC∈(-10°,40°),is the power side boundary fault,protect the instantaneous action.When the phase difference θUC∈(80°,130°),is the no fault line or no DG fault line,is an extra boundary fault;when the phase difference θUC∈(150°,230°),after the fault point with DG,Or a no fault line with a DG,is the DG external failure,protection time-delay action.The phase difference between fault phase voltage and zero sequence voltage is affected by transition resistance,neutral grounding resistance and line distribution parameters.When the capacitor current of the power grid reaches the extreme 700 A,the fault range within the boundary is expanded from(0.5°,14.8°)to(-6.5°,33°).In order to improve the adaptability of the criterion in extreme cases and consider a certain margin,the accuracy of the criterion is not affected,and the action angle of the protection criterion is larger than the calculation result. After simulation verification,the following conclusions are drawn:(1)The algorithm can accurately judge the power side boundary fault,extra boundary fault and DG external failure.Applicable DG neutral point by the small resistance grounding and not grounding two ways.(2)The algorithm can accurately judge the grounding fault in different grounding transition resistance conditions.Transition resistance up to 3 kΩ.At the different numbers of DG,different DG short-circuit capacity,different cable lengths,With load fluctuations and other on,can accurately judge the grounding fault.(3)The algorithm realizes the grounding fault judgment inside the protection device,without communication with the main station or device to achieve fault judgment,not affected by communication.(4)No need to install a zero-sequence voltage transformer,phase voltage can be obtained by electric field induction,the phase voltage can also be obtained by taking the capacitance of the circuit breaker on the primary and secondary deep fusion column,zero-sequence current can be synthesized by three-phase current,can be adapted to the type fault indicator scenario.It can also be applied to the circuit breaker scene on the primary and secondary fusion column.关键词
有源配电网/相电压与零序电流/相位差/小电阻接地系统/单相接地保护Key words
Active distribution network/phase voltage and zero sequence current/phase difference/small resistance grounding system/single phase grounding fault protection分类
信息技术与安全科学引用本文复制引用
李君,何敏,黄守道,刘君,刘志勇..基于相位差的小电阻接地有源配电网接地故障保护算法[J].电工技术学报,2024,39(23):7418-7429,12.基金项目
国家重点研发计划资助项目(2020YFB0906000). （2020YFB0906000）
