三相三线制系统电压不平衡度计算方法

A Method to Compute Voltage Unbalance Factor in Three-Phase Three-Wire System

三相电压不平衡度是衡量电能质量的重要指标之一。在三相三线制供电方式下,分析比较了目前计算三相电压不平衡度方法的精度和优缺点,提出了适用于三相三线制系统的电压不平衡度计算新方法。该方法无需通过复杂的向量计算,只需3个相电压的幅值就能精确计算出正序、负序分量及三相不平衡度。通过详细的公式推导和大量的实例计算证明了该方法的正确性。

Three-phase unbalance factor is one of the leading indicators in Power Quality. In this paper, the precision, the advantages and disadvantages of computing methods of three-phase unbalance factor in three-phases, three-lines series power supply are analysised and contrasted, and for the first time put forward a new method applicables to three-phase three-wire system named Vector Graphical Procedure, the new method doesn’t need complicated vector calculus, only uses magnitude of three-phase voltage, the positive-sequence, negative-sequence and three-phase unbalance factor can be calculated exactly, lots of practical examples have been done to prove the correctness of the method.