多电压等级直流电网的仿真技术与协调控制策略研究

Research on Simulation Technology and Coordinated Control Strategy of Multivoltage DC Grid

多电压等级的直流电网是未来直流输电技术的重要应用,其关键设备是直流变压器。然而,多电压等级直流电网的电磁仿真模型规模庞大,含直流变压器时的协调控制策略尚不清楚。对此,首先简单介绍了MCT(模块化组合式直流变压器)的运行原理。然后,基于平均开关函数提出了桥臂高等效性模型,用于加快电磁暂态仿真速度。最后,针对舟山五端柔性直流改造工程,研究了含MCT的多电压等级直流电网的协调控制策略。在PSCAD/EMTDC中搭建了基于桥臂高等效性模型的多电压等级直流电网仿真模型,验证了所提出桥臂等效模型以及协调控制策略的有效性。

Multi-voltage DC(MVDC)grid is an important application of DC transmission technology in the future,and its key equipment is DC transformer. However,the electromagnetic simulation model of the HVDC grid is large in scale and its coordinated control strategy in the context of transformers is still unclear. First,the operating principle of modular combined DC transformer(MCT)is briefly introduced;then based on the average switching function,an efficient equivalent model(EEM)of MMC bridge arms is proposed to accelerate the electromagnetic transient simulation. Finally,the coordinated control strategy of the MVDC grid with the MCT is studied. The EEM of MMC bridge arms and a multi-voltage DC grid simulation model are built in PSCAD/EMTDC to verify the EEM of MMC bridge arms and the effectiveness of the coordinated control strategy.