曲折接线变压器抑制零序三次谐波电流方法研究

Study of Reducing Zero-Sequence Third Harmonics by Zig-Zag Transformer

低压配电系统中非线性用电设备所产生的零序3次谐波会在中性线上叠加,使电流增大,可能对系统产生危害。本文对采用曲折接线变压器抑制3次谐波的方式进行了详细的分析和仿真研究。给出了曲折变压器的额定电压和容量选取原则以及参数的确定方法。对该方式抑制3次谐波的效果与变压器短路感抗变化、三相电压不平衡以及谐波不平衡之间的关系进行了分析,得到了当变压器短路感抗增大,三相电压不平衡度以及零序3次谐波不平衡过大时,此方式抑制谐波的效果变差的结论。给出了应用曲折接线变压器抑制零序谐波的若干适用场合。

The zero-sequence third harmonics of the nonlinear loads result in a significant neutral current in the distribution power system. It is will hazard the power system. The zig-zag transformer can attenuate the zero-sequence harmonics. This paper makes detailed analysis and simulation for applying this equipment to reduce third harmonics. The influence of leakage reactance, unbalance utility voltage and unbalance third harmonic current to the filter efficiency of this equipment has been analyzed. The simulation results show that the filter efficiency become bad when leakage reactance has been increased or under the situation of unbalance utility voltage and unbalance zero-sequence harmonics current. The varied situations that can be applied of this equipment have been proposed.