基于序电流的三相负荷不平衡度数学建模与度量分析

目前，基于序分量建立的三相不平衡度数学模型形式均不唯一，而且序分量在实践中不易测量，会给三相不平衡治理及因三相负荷不平衡带来的损耗分析带来诸多不便。基于3种三相负荷不平衡条件分别建立模型，提出了对应的三相负荷不平衡度算法。针对幅值和相位均不平衡的三相负荷不平衡电力系统，提出采用序分量有效值与三相平均电流有效值之比的平方和的倒数来度量三相负荷不平衡度，建立了三相序分量与三相负荷不平衡度的关系，统一了IEC提出的基于序分量的三相不平衡度量式。试验及案例分析表明，提出的三相负荷不平衡度算法可以有力反映不同条件下的三相负荷不平衡。对于低压供配电系统，所提出的三相负荷不平衡度算法与针对幅值和相位均不平衡的三相负荷不平衡电力系统提出的三相负荷不平衡度算法的度量结果具有一致性，对三相不平衡的治理及工程实践具有较强的实用价值。

Mathematical modeling and measurement analysis of three-phase load imbalance degree based on sequence current

At present, the mathematical model of three-phase imbalance degree based on sequence component is not unique, and the sequence component is not easy to measure in practice. This causes a lot of inconvenience to three-phase imbalance treatment and loss analysis due to three-phase load imbalance. Based on three kinds of three-phase load imbalance conditions, a corresponding three-phase load imbalance degree algorithm is proposed. For three-phase unbalanced load power systems with unbalanced amplitude and phase, the reciprocal of the square sum of the ratio of the effective value of the sequence component to the effective value of the three-phase average current is proposed to measure the three-phase load imbalance. The relationship between the three-phase sequence component and the three-phase load imbalance is established, and the three-phase imbalance measurement formula based on the sequence component proposed by IEC is unified. Experiments and case studies show that the proposed three-phase load imbalance algorithm can effectively reflect the imbalance under different conditions. For low-voltage power supply and distribution system, the proposed algorithm is consistent with the proposed three-phase load imbalance algorithm for three-phase power system with unbalanced amplitude and phase. This has strong practical value for the treatment of three-phase imbalance and engineering practice.