基于Dd匹配变和SVG的牵引变电所群贯通供电系统负序治理方案及控制策略

Negative Sequence Treatment and Control Strategy for the Co-phase Interconnected Power Supply System of Traction Substation Group Based on Dd Transformer and SVG

牵引变电所群贯通供电方案是解决长大坡道、外部电源短路容量小且接口少的电气化铁路供电问题的有效技术手段之一。针对牵引变电所群贯通供电系统负序治理问题,提出了一种基于Dd匹配变和静止无功发生器(static var generator,SVG)的负序治理方案及控制策略。介绍了牵引变电所群贯通供电系统的结构,分析了其各端口电气量及关系,提出了适用不同牵引负荷功率因数的两种负序治理模式,并推导了负序治理数学模型。考虑电网三相电压不平衡度允许值,分析了不同工况下Dd匹配变次边各端口SVG投入容量,提出了补偿模式间切换策略。根据负序治理方案确定系统负序电流检测方法,提出了一种SVG双闭环控制策略。最后搭建了仿真模型,仿真结果表明方案的有效性和控制策略的准确性。

The co-phase interconnected power supply system of traction substation group is a feasible technical solution to electrified railway power supply problem of long and steep slope, external power supply with poor short circuit capacity and lack of interface. Aiming at the problem of negative sequence current, a treatment scheme and its control strategy based on Dd transformer and SVG were proposed. The structure of co-phase interconnected power supply system of traction substation group was introduced, and the relationship of electrical quantity of its each port was analyzed. Then, two modes of negative sequence treatment were proposed, which were separately compatible to different traction load power factor. Meanwhile, a mathematical model was derived. The limit of three-phase unbalance was taken into consideration,and the reactive power capacity resolved by each SVG on secondary ports of the Dd transformer was analyzed when they were working under different conditions. Based on research above, a switching strategy between different modes was put forward. According to the scheme, the negative sequence current detecting methodology was determined and an SVG control strategy of double closed loop was proposed. Finally, the simulation model was built. Simulation results verify the effectiveness of the scheme and the accuracy of the control strategy.