Adaptive RoCoF Reference-Based Fast Frequency Response With Reduced BESS Operating Costs

Reduced system inertia in power syste ms with high renewable energy penetration poses challenges to frequency regulation. To address these issues, we propose a Fast Frequency Response (FFR) controller to maintain frequency within the predefined thresholds while reducing operating costs associated with Battery Energy Storage Systems (BESSs). To ensure frequency security under credible contingencies, the control gain of the FFR controller is determined offline, based on the worst-case scenario. To avoid excessive FFR during minor disturbances, we introduce an adaptive RoCoF reference that dynamically adjusts based on real-time estimations of power deficits and generator ramping capabilities. This approach tailors FFR needs to varying operational scenarios, including cascading failures, thereby effectively reducing FFR energy transfer and operating costs. Though our method is model-free with a simple mechanism, its energy efficiency is comparable to the controller using contingency-specific critical gains. The validation of the controller in a modified 9-bus test power system and a planned 2025 Taiwan high-renewable system demonstrates its adaptability across scenarios. Notably, across different contingencies and operating conditions, the average Energy Transfer Index (ETI) for the proposed controller is significantly lower than that of the zero reference controller, at 17.37% compared to 28.59%, respectively.