6kV中性点不接地配电网单相接地的危害及对策

天脊集团公司的6kV系统原来采用中性点不接地运行方式，由于配电网络庞大，电网对地电容电流大幅度增加，使得供电系统发生单相接地时，不但不能继续运行，而且经常发生相间短路、设备损坏和人身伤害等事故，严重威胁着供电可靠性。为此采取了两种方法，一是增加消弧线圈装置，当系统发生单相接地时，利用电感线圈产生的电感电流来补偿与之方向相反的电容电流，恰当地选择消弧线圈的分接头，就可使接地电流得到合理的补偿；二是补偿后由于残流较小，使得传统的接地保护不能正确动作。

Harm from the Single-Phase Earthing of 6kV Distribution Network with Neutral Point Unearthing and Countermeasures Against it

The paper describes that 6kV system of Tianji Group,in which the neutral point unearthing was originally adopted, not only can't continue operating, but there are frequently interphase short circuit, equipment damage and personal injury while the single-phase earthing occurs in power supply system because of the increasing current by a large margin from direct-to -ground capacitance resulted from large distribution network,which influences seriously the reliability of power supplying. We have taken two kind of measures. Firstly,to add arc suppression coil whick will compensate the earthing current by using inductance current from inductance coil compensate the reversed capacitance current in the case of single-phase earthing in the system,and the more proper the choice for tap of arc suppression coil is,the more reasonable the compensation is. Secondly,to use earthing select unit MLN98 for weak current in order to improve the original earthing protective performance which can't act functionly as a result of a little residue after being compensated.