一种利用零序功率方向的小电流接地系统单相接地故障选线判据  

Criterion for Single-phase Grounding Fault Line Selection for Small Current Grounding System by Using Zero Sequence Power Direction

作　　者：薛颢 李延军 程虎 XUE Hao;LI Yanjun;CHENG hu(PetroChina Lanzhou Petrochemical Company Power Plant ,Lanzhou, Gansu 730060 , Chin)

机构地区：[1]兰州石化公司动力厂,甘肃兰州730060

出　　处：《广东电力》2018年第4期132-138,共7页Guangdong Electric Power

摘　　要：针对谐振接地系统单相接地故障,分析了现有接地保护方法在小信号基础上提取特征信号的不足,基于瞬时功率理论,提出了一种利用零序功率方向的选线新方法。分析了零序能量对应不同元件的变化规律,通过对瞬时零序功率全信号n次积分累加的方法,得出故障特征可近似表述为关于时间的一元n次函数,且函数图像的开口方向由传统意义上零序有功功率的流向决定,故障线路和正常线路函数图像的开口方向完全不同,因此,通过对历史数据的n次积分累加可甄别故障线路;分析了"倒相"产生的原因及"倒相"发生时故障线路与正常线路零序电容测量值的不同特征,提出了"倒相"发生时甄别故障线路的方案。该选线方法充分利用故障全时段的信号,通过信号累加的方法持续放大故障特征,仿真表明该方法有效。In allusion to the single-phase grounding fault of the resonant grounding system,this paper analyzes shortage of current grounding protection method in extracting characteristic signals on the basis of small signals.Based on the theory of instantaneous power,it presents a new method for line selection by using zero sequence power direction.It analyzes variation laws of zero sequence energy corresponding to different elements and by means of the method of n-order accumulation of full signals of instantaneous zero sequence power,it deduces that fault feature can be approximately expressed as the unary n-order function about time,and opening direction of the function is determined by flow direction of zero sequence active power in traditional sense,while opening directions of functions of the faulted lines and normal lines are totally different.Therefore,by means of n-order accumulation of historical data,it is able to discriminate faulted lines.In addition,the paper analyzes reasons for phase inversion and different features of measured values of zero sequence capacitance of faulted lines and normal lines,and proposes a scheme of discriminating faulted lines as phase inversion occurs.This line selection method fully uses all-time signals of the fault and the accumulation method to continuously enlarge fault features.Simulation proves effectiveness of this method.

关 键 词：谐振接地系统 瞬时零序功率 n次积分 接地保护 

分 类 号：TM744.3[电气工程—电力系统及自动化]