Real-time Coordinated Control for Cascade Hydro-photovoltaic-pumped Storage Complementary Generation System

The cascade hydro-photovoltaic-pumped storage complementary generation system (CHPPSCGS) combined with a cascade small hydropower plant (CSHP), a distributed photovoltaic (PV) plant and a pumped storage unit, can smooth the PV power fluctuations and improve its schedulability. Regarding the real-time control problem of the CHPPSCGS, this paper proposes an empirical mode decomposition (EMD) based control strategy for using the full size converter based variable speed constant frequency pumped storage unit (FSC-VSCFPSU) to smooth the PV power fluctuations, including adaptively determining the smoothing goals and quickly deciding the compensation power of the FSC-VSCFPSU by analyzing the high and low frequency components of the PV power fluctuations obtained by using the EMD algorithm. The paper also proposes a CHPPSCGS power generation dispatch schedule (PGDS) tracking strategy based on the coordinated control of CSHP and FSC-VSCFPSU, which coordinately distributes the output power of the CSHP and the FSC-VSCFPSU to minimize the deviation between the CHPPSCGS output and the PGDS to ensure that the CHPPSCGS smoothly tracks the PGDS while smoothing PV power fluctuations. In addition, a virtual synchronous generator control strategy for the FSC-VSCFPSU based on its variable speed operation mode is given, which enables the FSC-VSCFPSU to have fast power response capabilities by emulating the characteristics of synchronous generators to control the grid-connected operation of the full size converter in the FSC-VSCFPSU, and ensures the effective execution of the control strategies of smoothing PV power fluctuations and tracking PGDS. The validity and feasibility of the proposed control strategies are verified by simulation and analysis with examples. © 2021, Power System Technology Press. All right reserved.