树形双边贯通供电系统运行策略及对外部电源的负序影响

Operation strategy of tree bilateral interconnected power supply system and the negative-sequence effect on external power supply

树形双边贯通供电系统能够实现长距离无分相贯通供电,提高系统的再生制动能量直接利用率。当树形双边贯通供电方案仅由单相接线变压器构成时,列车在公共连接点处产生的三相电压不平衡度将加剧,一旦负序超标,将面临负序带来的不利影响。为了确保系统的良好运行,避免负序带来的不利影响,有必要评估系统的负序情况。分别研究采用单相接线变压器和采用组合式同相供电装置构成的树形双边贯通供电系统及其运行策略,针对采用组合式同相供电装置的方式提出同相供电装置的就地控制策略。以公共连接点处三相电压不平衡度作为评估树形双边贯通供电系统对外部电源的负序影响的评估指标,分别构建传统Vv接线变压器的单边供电系统、采用单相接线变压器构成的树形双边供电系统和采用组合式同相供电装置构成的树形双边供电系统的负序评估模型。以某线路为例,基于构建的负序评估模型对采用树形双边贯通供电方案后的系统的三相电压不平衡度进行评估,并与既有供电方案的结果进行对比,采用单相组合式同相供电的树形双边供电改造方案后,三相电压不平衡度最大值为1.65%,95%概率大值为1.20%,均符合国家标准。结果表明采用树形双边贯通供电系统方案负序问题得到了极大的改善,符合国家标准的要求,也证明了本文同相供电装置运行策略的有效性。

The tree bilateral interconnected power supply system can realize long-distance interconnected power supply without electrical phase separation,which improves the utilization rate of regenerative braking energy of the system.When the tree bilateral interconnected power supply scheme is only composed of single-phase connection transformers,the three-phase voltage unbalance generated by the train at the common connection point will be aggravated.Once the negative sequence exceeds the standard,it will face adverse effects caused by the negative sequence.In order to ensure the good operation of the system and avoid the adverse effects of negative sequence,it is necessary to evaluate the negative sequence of the system.The tree bilateral interconnected power supply system and the operation strategies were studied which including the system using single-phase transformer and the system using combined co-phase power supply device.A local control strategy was proposed for the method of using co-phase power supply device.The three-phase voltage unbalance at the point of common coupling was used as the evaluation index to evaluate the negative sequence influence of the tree bilateral interconnected power supply system on the external power supply,and negative sequence evaluation model of traditional unilateral power supply system based on Vv connection transformer,the tree bilateral interconnected power supply system composed of single-phase connection transformers and the tree bilateral interconnected power supply system composed of combined co-phase power supply devices were constructed respectively.Taking a line as an example,based on the negative sequence evaluation model constructed,the threephase voltage unbalance degree of the system after adopting the tree bilateral interconnected power supply scheme was evaluated,and compared with the results of the existing power supply scheme.After the tree bilateral interconnected power supply transformation scheme of the co-phase power supply was adopted,the maximum value of the three-phase voltage unbalance was 1.65%,and the maximum value of the 95%probability was 1.20%,which were all in line with the national standards.The results show that the negative sequence problem has been greatly improved under the tree bilateral interconnected power supply scheme,which meets the requirements of national standards,and also shows the effectiveness of the operation strategy of the co-phase power supply device in this paper.