多端柔性互联的交直流配电系统分层控制策略

Hierarchical Control Strategy for Multi-terminal Flexible Interconnected AC/DC Power Distribution Systems

针对多端柔性互联的交直流配电系统中多功率变换单元协调控制及系统整体能量管理问题,提出了一种基于不同时间尺度的分层控制策略。第1层控制为各功率变换单元的调制方式与基本控制方式,保证各功率变换单元能正常实现其功能。第2层控制依据系统直流母线电压将系统划分为3个运行区间、5种工作模态,并依照不同工作模态生成第1层控制指令,切换系统中柔性互联装置、光伏发电单元、蓄电池储能单元的控制策略,实现系统在正常及故障工况下的稳定运行。第3层控制对新能源利用率最大、系统损耗最小、蓄电池荷电状态最佳、系统购电成本最少等多个目标进行综合优化,生成第2层调度指令,实现系统正常运行工况下的优化运行。最后通过系统仿真对所提控制方案进行验证,系统可以根据所述控制方案在各工作模态下切换,同时可以实现系统的最优能量调度。

Aiming at the problems in the coordination control of multi-power conversion unit and system energy management in multi-terminal flexible interconnected AC/DC power distribution systems,we propose a hierarchical control strategy based on different time scales.The first layer control is the modulation mode and basic control mode of each transform unit,ensuring that each transform unit can normally perform its function.The second layer control achieves stable operation of the system under normal and fault conditions,it divides the system into three operating intervals and five working modes according to the DC bus voltage of the system,and generates a first layer of control commands according to different working modes,which is used to switch the flexible interconnecting device and the photovoltaic power generating unit in the system.The third layer control comprehensively optimizes multiple targets such as maximizing the new energy utilization,minimizing the system loss,optimizing the state of charge of battery,and minimizing the system total electricity price,thus generates second-level scheduling instructions to achieve optimal operation under normal operating conditions of the system.Finally,the proposed control scheme is verified by system simulation.The system can be switched according to the control scheme in each working mode,and the optimal energy scheduling of the system can be realized at the same time.