A Grid-following and Grid-forming Collaborative Control Strategy for Enhancing the Active Support Capacity of Photovoltaic Power Plants

In the context of power transmission from large-scale photovoltaic (PV) bases located in the desert, Gobi, and barren lands, conventional PV power plants face challenges of insufficient frequency and voltage support capabilities. For grid-following(GFL) and grid-forming(GFM) hybrid PV power plants, a frequency and voltage collaborative control strategy is proposed to enhance their active support capability. Firstly, considering variations in solar irradiance and the P-V output characteristics of PV arrays, a GFM PV control strategy based on variable reserve capacity ratio is proposed to provide the energy required for active support. Subsequently, by balancing active support capability with economic considerations, a collaborative control strategy for frequency and voltage active support, suitable for GFL/GFM hybrid PV plants, is introduced. Finally, case studies on a practical grid-connected PV power plant demonstrate that, compared with traditional control strategies, the proposed collaborative control strategy for hybrid PV plants can effectively reduce the variation ranges of AC system frequency and voltage under different types of disturbances. The proposed collaborative control strategy for hybrid PV power plants can significantly enhance their active support capability for AC system voltage and frequency. This advancement facilitates the transition of PV generation from an auxiliary power source to a primary one.