1、河南理工大学毕业设计（文档）说明书 1 Participants distribution network neutral point earthing way Summary : comparison of the distribution network neutral point of the advantages and disadvantages of different methods grounded. To the distribution network on the resistance grounded electricity reliability, communica
2、tions, physical security, the impact of switching to an analysis that must be based on the actual situation grid conditions, taken together, a reasonable choice of neutral point earthing, capacitance currents, the distribution network can still use small non-grounded approach to capacitance currents
3、 larger, overhead lines on the distribution network should choose automatic tracking wave half circle grounded approach to cable-based distribution network, the resistance grounded neutral point is the preferred approach. Keywords : neutral point earthing; Resistance grounded; Eliminate half circle;
4、 Resistance value choice 1. Neutral point earthing way Three-phase power grid neutral exchange points and electrical connections between the earth, known as the neutral point grounding grid. Different ways of neutral point earthing grid insulation levels, and over-voltage protection components worth
5、 selection, the reliability of electricity supply, electricity conservation, physical 河南理工大学毕业设计（文档）说明书 2 security and equipment, communications jamming, and electromagnetic compatibility, investment costs will cause different effects. Therefore the choice of neutral point earthing is a comprehensiv
6、e manner, must be based on systems, power grids structure, a comprehensive analysis of capacitance current size can reasonably choose neutral point earthing. My early have : electricity system will be neutral point earthing way into large and small grounded grounded short circuit current system shor
7、t circuit current system categories. Electric arc generally considered grounded out to the grounded since the current system for small Earth System, grounded electric arc not since the grounded out to the current system earthing system. Current size is used for power system neutral earthing point to
8、 clearly defined classification method, and therefore were effectively grounded into neutral point neutral point system and non-effective earthing system. Power system neutral point effectively grounded, including direct grounding or through low resistance devices or low reactance devices grounded,
9、effective earthing grid characteristics : system-wide zero sequence reactance (Xo) is a serial reactance (x1) than (Xo/ x1) is and less than 3% serial resistance (Ro) is a serial reactance (x1) than for being and less than or equal to 1. Effective earthing system in the neutral point, in the case of single-jointed to failure, the failure of the 河南理工大学毕业设计（文档）说明书 3 larger fault current through the greatest value may exceed the three-phase short-circuit fault current, at the failure of the non-stable voltage to no more than 80% of line voltage. Instead neutral point for the non-effective eart
