Optimization of frequency support parameters and control considering GFL/GFM ratio in heterogeneous renewable energy plants

Under high penetration of wind and photovoltaic power, the frequency dynamic security issues of multi-source heterogeneous renewable energy plants become prominent, creating an urgent need for active system frequency support during disturbances. While increasing the proportion of grid-forming converters (GFM) enhances frequency support capability, it sacrifices plant generation revenue. To address this, this paper establishes a frequency response model for a multi-source plant system considering the hybrid ratio of grid-following converters (GFL) to GFM. It quantitatively analyzes the sensitivity of key control parameters to frequency dynamic characteristics and reveals the mechanism by which energy storage units trigger secondary frequency dips when operating at state of charge (SOC) boundaries. Based on frequency security boundary indicators, a frequency security operation region for the plant is constructed. Furthermore, a parameter optimization method and a control strategy are proposed, balancing active frequency support capability with economic efficiency. Simulation verification based on a modified IEEE 9-bus system demonstrates that the proposed strategy significantly enhances system inertia response and primary frequency regulation capability. Simultaneously, it optimizes plant operational revenue and effectively suppresses secondary frequency dips under critical SOC conditions.