配电网三相不平衡对线损增加率及电压偏移的影响

随着配网规模增大,用电负荷不断增多,三相负载不平衡现象严重影响了电网的稳定运行,不仅增加了配网损耗还降低了电能质量。文中推导出三相不平衡度与线路损耗增加率的关系公式,不仅考虑三相电流大小不对称,也结合实际情况分析了三相电流相位波动对损耗影响。全面分析了不平衡度-配变负载率-电压偏移三者的关系,提出了基于不平衡度指标下的电压偏移度预警方法。最后结合黄岛某小区具体工程实例以及上述推导公式得出结论,配电网三相不平衡对线损增加率及电压偏移都有一定影响,且其相关性不可忽略。可为配电系统运行决策提供参考,对配电网供电质量提高具有积极作用。

Influence of Distribution Network Three-phase Unbalanceon Line Loss Increase Rate and Voltage Offset

With the increasing scale of the distribution network, the increasing load of electricity, the three-phase load imbalance seriously affected the stable operation of the power grid. Not only distribution network loss increases, power quality are also reduced. The relationship between the three-phase unbalance and the increase rate of the line loss is deduced, which not only considers the asymmetry of the three-phase current, but also analyzes the influence of the phase. The relationship between unbalanced-distribution load-voltage offset is analyzed comprehensively, and the method of warning of voltage offset based on unbalance index is proposed. Results show that the three-phase imbalance has certain impact on the line loss increase rate and voltage offset, and the correlation cannot be neglected, combined with the specific engineering example of Huangdao area and above derivation formulas. It can provide reference for the operation decision of distribution system and have positive effect on the improvement of power supply quality of distribution network.