基于瞬时实功率和瞬时虚功率的谐振接地系统单相接地选线新方法

A New Integration Method of Fault Line Detection in Resonant Earthed System Based on Instantaneous Real Power and Instantaneous Virtual Power

谐振接地系统发生单相接地故障时故障信号复杂且暂态信息丰富。本文基于瞬时功率理论,提出了采用瞬时实功率和瞬时虚功率的复合选线新方法。谐振接地系统发生单相接地故障时,与健全线路不同,故障线路由于消弧线圈的补偿作用将在接地电流中产生暂态衰减直流分量,通过瞬时实功率和瞬时虚功率分析表现为明显的工频衰减振荡特征。文章确定50Hz为瞬时功率分析的特征频率,通过分别计算故障时各线路瞬时实功率和瞬时虚功率,进一步分解出其振荡分量,综合比较特征频率上各线路瞬时实功率及瞬时虚功率振荡分量的大小来构造选线算法从而检出故障线路。该方法利用暂态信息,多判据复合、不涉及相位分析、实现容易、可靠性高。仿真表明该方法有效。

The accident transition information is not only complex but also enrichment when single-phase-to-ground fault occurs in resonant earthed system. A new integration method of fault line detection based on instantaneous real power and instantaneous virtual power is proposed in this paper. Not as health lines, when single-phase-to-ground fault occurs in resonant earthed system, the grounded current of faulty line contains distinct transition damping oscillation direct current component with the compensation of arc suppressing. The damping oscillation direct current component shows the characteristics obviously of damping oscillation of industrial frequency through the analyses of instantaneous real power and instantaneous virtual power. Here, the characteristic frequency of 50Hz in instantaneous power theory is defined. By calculating the instantaneous real power and instantaneous virtual power respectively of each line after single-phase-to-ground fault occurred, the oscillator components can be decomposed. Through comprehensively analyzing the value of oscillator components with the characteristic frequency of instantaneous real power and instantaneous virtual power, the integration algorithm of fault line detection can be established. The new method makes full use of transition information without considering phase position and multiple distinguish. Large amount of simulation results shows that the proposed method is accurate and reliable.