DC Traction Power Supply System Based on Modular Multilevel Converter Suitable for Energy Feeding and De-icing

A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel converter (MMC). The FBSM-MMC is a novel type of voltage source converter (VSC) and can directly control the output DC voltage and conduct bipolar currents, thus flexibly controlling the power flow of the urban rail transit catenary. The proposed topology can overcome the inherent disadvantages of the output voltage drop in the diode rectifier units, increase the power supply distance and reduce the number of traction substations. The flexible DC technology can coordinate multiple FBSM-MMCs in a wide area and jointly complete the bidirectional control of catenary power flow during the operation of the electric locomotive, so as to realize the local consumption and optimal utilization of the recovered braking energy of the train. In addition, the FBSM-MMCs can also adjust the output current when the locomotive is out of service to prevent the catenary from icing in winter. The working modes of the proposed topology are illustrated in detail and the control strategy is specially designed for normal locomotive operations and catenary de-icing. Simulation cases conducted by PSCAD/EMTDC validate the proposed topology and its control strategy.

基于禁忌搜索算法的直流融冰计划优化决策

鉴于输电线路在开展直流融冰工作时可能导致系统运行可靠性和输电能力降低的问题,提出一种电网直流融冰计划决策的优化模型。优化模型以全部待融冰线路的融冰时段组合为决策变量,以整个直流融冰周期内因直流融冰引起的系统期望缺供电量的增量最小为目标,采用禁忌搜索算法对待融冰线路的融冰时段进行优化,同时融冰紧急性指标以约束条件的形式能一定程度上保障线路得到及时融冰。通过实际算例验证所提出方法的可行性和有效性。

基于等风险度法的电网直流融冰计划决策

针对电网直流融冰计划的编制需兼顾系统安全及线路安全的问题,提出了基于等风险度法的电网直流融冰计划决策方法。该方法以等期望切负荷量为目标函数,结合已确定的线路直流融冰计划及约束条件,按照线路重要性综合指标依次安排各线路的融冰时段。每次决策时,若出现强受制性线路需优先安排,然后按蒙特卡罗方法计算所选线路可融冰时段的期望切负荷量并安排在其值最小时段。一条线路的融冰时段确定后,更新剩余待安排线路的约束条件,进入下一线路融冰时段的决策。此外,融冰紧急性作为约束条件用以保障线路的安全性。最后,贵州电网的实例验证了方法的有效性和可行性。