10kV母线电压不平衡分析

Analysis of Unbalanced 10 kV Bus Voltage

分析了一起某10 k VTV一次中性点与地之间加装消谐器后导致10 k V母线电压不平衡的故障。通过检查TV铭牌,发现三相TV型号不一致,其中A、C相为呈容性电磁式电压互感器,而B相为呈感性电磁式电压互感器,因此初步判定该故障是由三相TV结构不同引起。进一步对故障时的等效电路分析,查找出故障的根本原因是加装消谐器后,三相TV的一次阻抗不同,导致中性点电压偏移。

A 10 kV Bus voltage unbalance fault after the installation of harmonic eliminator between the primary neutral point of 10 kV TV and ground is analyzed. By checking the nameplate of TV, the inconsistent of three phase TV model is found in which A and C phase are capacitive electromagnetic voltage transformer while B phase is inductive electromagnetic voltage transformer. So it is preliminarily concluded that the fault is caused by the different structure of three phase TV. By further analysis of the equivalent circuit during the fault, it is found that the fundamental reason is the difference of primary impedance after the installation of harmonic eliminator which caused the offset of neutral pint voltage.