基于电流修正的智能接地配电系统高阻接地故障选线判据优化方法

Optimization method of line selection criterion for high resistance groundingfault in smart grounding power distribution system based on current correction

智能接地配电系统所用选线判据具有所有线路动作门槛统一的优点,但灵敏性较差,运用其进行选线存在高阻接地故障时保护易拒动问题。电流修正选线法在高阻接地故障时依然能正常选线,但每条线路动作门槛须单独整定,较为繁琐。为解决上述问题,本文结合原判据与电流修正方法,提出一种兼具二者优点的新判据,有效应对高阻接地故障的同时,保留了动作门槛统一的优点,无须其他线路电气特征即可完成选线。新判据在原理上不受过渡电阻影响,耐过渡电阻能力只取决于测量设备精度。经Matlab建模仿真,验证了方法的有效性及新判据的可靠性,仿真结果表明,本文方法能有效应对4 000Ω以下的高阻接地故障。

The fault line selection criterion used in smart grounding power distribution system has the advantage of having uniform threshold for all lines,but the sensitivity needs to be improved,and there is a problem to use it in line selection that the protection is easy to failure when high resistance grounding fault occurs.The current correction line selection method can also normally select lines in case of high resistance grounding fault,but the action threshold of each line must be set separately,making it becomes more complicated.In order to solve the above problems,this paper proposes a new criterion combining the original selection criterion and current correction method,which has of both the advantages.It can effectively deal with high resistance grounding fault while retaining the advantages of uniform threshold,and can complete the line selection process without the need of knowing thelectrical characteristics of other line.The new criterion is not affected by transition resistance in principle and its ability to withstand transition resistance only depends on the accuracy of measuring equipment.The effectiveness of the proposed method and the reliability of the new criterion are verified by Matlab modeling and simulation.The simulation results show that the proposed method can effectively deal with the grounding fault with high resistance within 4000Ω.