20kV配电电压等级的接地方式研究

Research of Neutral Grounding Modes in 20kV Distribution Network

针对20 kV城市电缆配电网出现的单相接地故障电流增大以及接地后过电压问题.研究适合20 kV配电不同网络结构的中性点接地方式.通过对20 kV配电网中性点不接地、经消弧线圈接地、经电阻接地3种方式进和接地故障稳态分析、暂态分析和系统参数分析,并与10 kV配电网接地方式相比较,说明20 kV配电网接地方式应用范围,当系统电容电流小于10 A时可采用中性点不接地方式;当系统电容电流在10-15 A之间时可采取消弧线圈接地方式;当系统电容电流在100-1 000 A之间时可采用低电阻接地方式;算例分析表明20 kV电缆配电网宜采用中性点经低电阻接地方式.

For the problems of the single-phase to ground fault current increased and the over-voltage in the 20 kV urban cable distribution network,the neutral grounding modes for different structures are studies.Application scopes of neutral grounding modes in the 20 kV distribution network are confirmed by the steady-state analysis and transient analysis of single-phase to ground fault,and the analysis of system parameters.When the capacitive current is less than 10 A.the insulated grounding mode can be used.Between 10～150A,the arc-suppression coil grounding mode can be used.Between 100～1000 A.the low-resistance grounding mode can be used.The analysis result shows that the mode of the neutral grounding via lowresistance should be applied in the 20 kV cable distribution network systems.