Extended Disturbance-Observer-Based Virtual Synchronization Control Strategy for Distributed Generation Clusters

This paper presents a disturbance-observer-based virtual synchronization control strategy for DG (distributed generation) clusters. The design process of inertia control structure of virtual synchronous generator is firstly adopted for DG clusters. Then the integrated small-signal virtual synchronization control characteristics is derived considering the DG output power fluctuation and load power fluctuation, which shows that system response needs further enhancement for expected dynamic recovery. To suppress the impact of external disturbances on system response, the extended disturbance-observer both for active and reactive power is proposed in this paper to estimate the external power disturbances and then enhance the robustness of the virtual synchronization control for DGs. The dynamic response analysis of the extended disturbance-observer for DG clusters is also conducted to demonstrate the anti-disturbance performance of the proposed control strategy. Theoretical stability analysis and simulations on PSCAD/EMTDC verify the validity and superiority of the proposed control strategy.