基于柔性多状态开关的主动配电网负荷在线紧急转供策略

配电网故障后,传统基于联络线的负荷转供方法存在停电转供、容易引起非故障线路过负荷等诸多问题。近年来出现的一种配电灵活交流输电(DFACTS)设备——智能软开关为上述问题的解决提供了契机。依托其对多条相连线路功率的柔性调节能力,提出了一种兼顾故障馈线残余负荷以及非故障馈线安全运行约束的负荷快速在线转供策略。首先建立了线路末端功率和各节点电压的关系,设置满足配电网正常运行状态的约束条件;在此基础上,以最大负荷转供量为上层目标函数,以电压偏差最小为下层目标函数,在约束范围内进行求解,获取最优潮流分配方法。最后针对上述最优潮流可能影响非故障馈线的安全运行的特殊场景,提出了在保证正常线路安全运行前提下最大程度保全待转供负荷的紧急切负荷策略和实现方案。依托大江东工程实际拓扑结构,搭建了基于PSCAD-MATLAB的联合仿真平台。结果表明,所提出的方案能够实现负荷的不断电在线转供。

Flexible Multi-state Switch Based Online Emergency Load Transferring Strategy for Active Distribution Network

There are some problems in the traditional load transferring scheme based on tie-lines such as long time failure and overload of non-faulty feeders after distribution network fails. In recent years, a kind of distribution flexible AC transmission system(DFACTS)device(i. e. soft normal open point)emerges and provides a possible approach to solve that problem. Based on its flexibility to adjust the power of multiple connected lines, an online load transferring criterion is proposed with the consideration of residual capacity of faulty feeders and the stability of non-faulty feeders. Firstly, the equation relationships between the power at the end of the line and the voltages of each node are established. Meanwhile, the constraints that satisfies the normal operation of distribution network are defined. On this basis, the upper objective function is the maximum transferring load, and the lower objective function is the minimum voltage deviation. Then, the optimal power flow allocation method is obtained by solving the objective functions within the above constraints. Finally, considering the special scenario in which the above optimal power flow allocation method may affect the safe operation of non-faulty feeders, an emergency load shedding strategy and the implementation scheme are proposed. It maximizes the maintenance of the load to be transferred with the premise of ensuring the safe operation of non-faulty feeders. Based on the actual topological structure of the Dajiangdong project of China, a joint simulation platform based on PSCAD and MATLAB is established. The result of simulation shows that the proposed strategy can realize the online load transferring with continuous power supply.