Hierarchical Improvement of Power Quality and Power Sharing for Interconnected Multivirtual Synchronous Generators

In interconnected multiple virtual synchronous generator (VSG) systems, issues such as power quality degradation and disproportional reactive power sharing arise frequently. In this article, a power quality improvement and power sharing strategy based on a hierarchical architecture is proposed. This strategy can improve both the dynamic performance and steady-state performance of the interconnected system. First, a state-space model for interconnected multi-VSG systems is established. Subsequently, a hierarchical compensation control structure based on residual is designed. This structure encompasses a power quality improving controller at the power electronic layer and a distributed power sharing controller at the network communication layer. Significantly, these controllers do not necessitate the extraction of disturbance information or line parameter information, nor do they require modification of the system’s original controllers. Moreover, they possess the merits of low-order complexity, convenient solution, and rapid response. The overall stability of the hierarchically controlled interconnected systems is validated via small-signal analysis. Finally, comprehensive physical experiments and simulations confirm the efficacy of the proposed strategy.