配电网电容电流的准确预测

Exact prediction of capacitive current for distribution network

配电网电容电流的准确测量是消弧线圈调节、补偿消弧的前提。本文分析了现有电网电容电流检测方法的特点;提出了单相附加电阻预测故障接地电容电流的新方法;该方法通过测量单相附加电阻后的电网零序电压和接地电阻上的电压,就能在电网正常运行时准确预测出电网发生单相接地故障时的电容电流。设计了基于此新方法,利用DSP实现的智能型电容电流预测装置方案;利用模拟电网对装置预测的准确性进行了验证。结果表明,该系统不仅能准确预测电网发生单线接地故障时的电容电流、对地绝缘电阻电流、接地点的残流等影响熄弧的关键参数,还能检测谐振电网的补偿状态,且操作安全、测量迅速、简便易用。

Existing schemes＇ characteristics to measure capacitive current are analyzed in order to measure capacitive current of distribution network, and then to adjust arc-suppression coil for extingushing electric arc of single phase to earth. The new exact predication scheme of capacitive current is put forward, which is based on a resistance added single-phase line. Using this new method, single-phase ground fault capacitive current is predicted through examining zero sequence voltage and voltage of grounding resistance in normal running condition of distribution network. The intelligent capacitive current measurement device using this new method and DSP is designed. Validity of this new system is testified by giving a distribution network example. The results show that capacitive current, insulation resistance current, remains current, etc., and key parameters of single phase grounding fault can all be exactly predicted, that compensating state of system can be checked at the same time, using the discussed capacitive current prediction system, when distribution network is running normally. This new device is easier to operate, more accurate, more fast and more safe than other methods.