接线方式引起的中性点位移形成三相电压不平衡

Three-phase voltage unbalance formed by displacement of neutral point caused by connection mode

镇湖闸供电系统将10kV高压电缆引入闸内干式变压器(SC10-50/10)降压至0.4kV供设备及办公使用,相电压不平衡且最大电压偏差达10.68%。为解决电压不平衡且偏差大的问题,对水闸电气回路进行详细分析,找出造成此问题的原因一是零线接线方式不当;二是采用变压器接线组别为Yyn-12时,变压器低压侧输出电压易产生不平衡。通过改变零线接线方式,可缓解电压不平衡且偏差大的问题;通过更换Dyn-11接线组别的变压器,并合理分配负荷,可彻底解决电压不平衡且偏差大的问题。

The dry type transformer(SC10-50/10)is introduced into the power supply system of Zhenhu Gate to decrease the 10kV high-voltage cable to 0.4 kV for equipment and office use.The phase voltage is unbalanced and the maximum voltage deviation is 10.68%.In order to solve the problem of unbalanced voltage and large deviation,the gate electrical circuit is analyzed in detail to find out the cause of this problem.One reason is that the connection mode of the null line is improper;second,when the transformer wiring group is Yyn-12,the output voltage on the low voltage side of the transformer is easy to produce imbalance.By changing the connection mode of the null line,the problem of unbalanced voltage and large deviation can be alleviated.By replacing the transformer of Dyn-11 wiring group and distributing the load reasonably,the problem of unbalanced voltage and large deviation can be completely solved.