平衡单相牵引负荷补偿容量优化设计

Optimum Design of Compensation Capacity for Balancing the Single-phase Traction Load

针对交流电气化铁路采用Steinmetz补偿电路实现三相平衡所需补偿容量很大的问题,以三相补偿装置总容量最小为目标,运用优化技术提出了一种合理的补偿容量最优方法。首先推导各相间补偿容量与电流不对称度系数及功率因数的关系,当功率因数和电流不对称度系数在允许范围内时,建立各相间补偿容量和平衡容量的数学模型。然后将优化问题转化为数学规划问题,利用优化方法推导最优补偿容量的解析结果。通过MATLAB计算,与Steinmetz电路所需补偿容量进行比较,证明上述结果在性能满足要求的前提下,在补偿容量数值上有明显优势。具体实例计算表明,所述优化设计方法可以以较小的补偿容量达到较好的补偿性能。

In view of the Steinmetz circuit usually used for balancing the single-phase load of the AC electrified railway that requires very large compensation capacity, a rational optimum capacity compensating method is proposed using the optimization technique with minimal total capacity of the three-phase compensation device as the objective. First, the relationship among the phase-to-phase compensation power, the current unbalance degree and system power factor is deduced. When the system power factor and the current unbalance degree are within the allowable ranges respectively, a mathematical model for the phase-to- phase compensation capacity of balancing the single-phase load is developed. By solving the mathematical problem with the Optimum method, the analytical results of the compensation capacity are obtained. Comparisons between the optimal results and those of the original Steinmetz circuit are made by MATLAB simulations, which demonstrate the obvious advantages of the optimum design. A case study shows that the system can be balanced by the optimal capacity with acceptable performance and less cost.