基于模块化多电平换流器(Modular Multilevel Converter,MMC)的多端直流输电(Multi-Terminal HVDC,MTDC)系统被应用于海上风电场并网,其控制策略对于电力系统的稳定性有着重大的影响。文章分析了MMC典型控制系统,结合海上风电场MMC-MTDC并网系统的下垂控制策略,建立MMC及其控制系统的简化状态空间方程;提出了一种基于模型预测控制(Model Predictive Control,MPC)的MMC控制方案,对d轴分量的有功功率和直流电压采用模型预测控制。通过PSCAD中基于4端MMC-MTDC的海上风电并网系统的仿真测试,验证了所提方法的可行性和有效性。
Due to the development of power electronic technology, modular multilevel converter (MMC) based multi-terminal HVDC (MTDC) has a promising future in off-shore wind farm integration, and its control strategy has great impact on the stability of power system. Combined with the droop control strategy of MMC-MTDC with offshore wind farms, a simplified state space equation of MMC and its control system is established. Meanwhile, a model predictive control (MPC) strategy for MMC is proposed.