Adaptive Primary Frequency Regulation of Wind–PV Renewable Energy Stations Considering Frequency-Drop Risk and Executable Reserve Credibility

High penetrations of converter-interfaced wind and photovoltaic (PV) generation erode synchronous inertia and make plant-level frequency support increasingly dependent on time-varying active-power headroom. Here we propose a risk-credibility-recovery primary frequency regulation (RCR-PFR) strategy for wind–PV renewable energy stations. The controller maps frequency excursion and negative rate of change of frequency (RoCoF) to a bounded frequency-drop risk index, converts reserve margin, resource volatility, downward trend, ramp-rate feasibility, and saturation margin into an executable-reserve credibility index, and dispatches wind and PV support under capacity and ramp-rate constraints. A recovery-debt term retards premature support withdrawal, while a battery energy storage system (BESS) compensates only the residual demand that remains infeasible after wind–PV projection. In the standard load-step case, RCR-PFR raises the frequency nadir to 49.788 Hz, 0.132 Hz higher than the no-renewable-PFR case, and reduces the secondary frequency dip by 73.4% relative to fixed-ratio allocation. In a constrained-reserve stress case, H = 3.0 s denotes a low-equivalent-inertia condition and the 0.105 p.u. disturbance corresponds to a 105 MW load increase on a 1000 MVA base. Under this condition, residual BESS compensation raises the nadir from 49.595 Hz to 49.813 Hz, limits the maximum frequency excursion to 0.187 Hz, eliminates the 4.24 s low-frequency interval below 49.8 Hz, and reduces unmet support energy from 1.2324 MWh to 0.0114 MWh. These single-area simulations indicate that RCR-PFR can improve frequency-security margins, executable-reserve utilization, and withdrawal-stage stability, although multi-machine, electromagnetic-transient, hardware-in-the-loop, and field validation remain necessary before plant-level deployment.