摘要
为解决小电流接地系统中高阻接地故障选线准确率低的问题,从主动调控中性点电压角度出发,提出一种基于零序电流变化量的多判据接地故障选线方法。在特制接地变压器系统侧均匀设置多个接地挡位,系统发生单相接地故障后柔性调节接地档位大小,将故障相电压抑制到故障电弧重燃电压以下。若故障电弧无法熄灭,判断线路发生永久性接地故障,通过降低变压器接地档位,放大故障馈线零序电流、减小非故障馈线零序电流,利用降档前、后各馈线零序电流增减差异进行选线。在过渡电阻较大的情况下,非故障馈线零序电流呈线性变化趋势,故障馈线零序电流呈非线性变化趋势,利用各馈线零序电流非线性畸变程度辅助选线。仿真结果表明,该方法针对瞬时性接地故障能够实现故障电弧快速熄灭,针对永久性接地故障可准确识别十数千欧接地故障馈线,有效提高小电流接地系统高阻故障选线准确率。
In order to solve the low accuracy of high-resistance grounding fault selection in small-current grounding systems,a multi-criteria grounding fault selection method based on the changing amount of zero-sequence current is proposed from the perspective of active regulation of neutral point voltage.Multiple grounding levels are uniformly set on the system side of the special grounding transformer.When a single-phase ground fault occurs in the system,the grounding level size is flexibly adjusted to suppress the fault phase voltage until no higher than the fault arc reignition voltage.If the fault arc can not be extinguished,the line will be judgedas a permanent ground fault line.In that case,the transformer grounding level will be decreased to amplify the fault feeder zero sequence currentand the non-fault feeder zero sequence current.The difference between the zero sequence current increase and decrease of each feeder before and after the lowering gear level can then be incorporated for line selection.Next,in the case of large transition resistance,the non-faulted feeder zero sequence current has a linear trend and the faulted feeder zero sequence current has a non-linear trend,and the degree of this non-linear distortion of each feeder zero sequence current can be exploited in line selection.Simulation results show that the method can achieve rapid extinguishing of the fault arc for transient grounding faults,can accurately identify ten kilo-ohm grounding fault feeders for permanent grounding faults,and effectively improving the accuracy of high resistance fault selection for small current grounding systems.
作者
白浩
黄升平
潘姝慧
李珊
袁智勇
BAI Hao;HUANG Shengping;PAN Shuhui;LI Shan;YUAN Zhiyong(China Southern Power Grid Research Institute Co.,Ltd.,Guangzhou 510663,China;Chongzuo Power Supply Bureau,Guangxi Power Grid Co.,Ltd.,Chongzuo 532299,China;Electric Power Science Research Institute,Guangxi Power Grid Co.,Ltd.,Nanning 530023,China)
出处
《电力科学与技术学报》
CAS
北大核心
2022年第4期105-113,共9页
Journal of Electric Power Science And Technology
基金
广西电网有限责任公司科技项目(ZBKJXM20190061)。
关键词
小电流接地系统
中性点电压
档位调节
故障选线
零序电流变化量
故障辨识
small current grounding system
neutral point voltage
gear level adjustment
fault line selection
zero sequence current change
fault identification
