基于不同时间尺度的交直流混合配电网分层优化控制策略

针对传统控制策略难以兼顾交直流混合配电网潮流优化和运行模式快速切换的问题,提出了一种基于不同时间尺度的分层控制策略。在较短时间尺度内,各并网变流器均根据上层调度指令工作于下垂控制模式,使系统稳定时工作于优化状态;当出现恶劣工作状况时,通过切换互联变流器和储能单元变流器的控制策略以维持配电网直流侧电压稳定。在较长时间尺度内,当系统正常运行时以系统电能损耗最小和系统电压偏差最小为优化目标;当直流线路断线时以故障点两侧节点电压偏差最小为优化目标,通过优化调度算法为下层提供调度指令。仿真结果表明:正常运行时该控制策略能实现系统运行优化、维持系统稳定且不过分依赖通信系统;在系统功率骤变、电路故障等恶劣工况时,能实现系统运行状态的平稳过渡。

Hierarchical Optimization Control Strategy for AC/DC Hybrid Distribution Network Based on Different Time Scales

This paper replaced the traditional control with a hierarchical control based on different time scales to solve the existing conflict between power flow optimization and operation mode in hybrid AC/DC distribution network.In short time scale,each grid-connected converter operates in the droop control mode according to the upper-level scheduling command,so that the system works in an optimized state when the system is stable.When the working conditions worsen,the control over interconnected converter and the energy storage unit is switched on to stabilize the DC side voltage of the distribution network.In the longer time scale,the optimization target is minimum system power loss and voltage deviation when the system is in normal operation.When the DC line is disconnected,the optimization target is minimum voltage deviation of the nodes on both sides of the fault point,and the optimal scheduling algorithm provides scheduling instructions for the lower layers.The simulation results show that the improved control strategy optimizes the system operation,maintains the system stability and does not over-depend on the communication system in normal operation.It stabilizes system operation in the cases of severe power fluctuations such as system power failure and circuit failure.