Intelligent Load Frequency Control for Hybrid System With Renewable Integration

This research investigates load frequency control (LFC) in hybrid power systems (HPS) with large-scale renewable energy sources (RESs). An intelligent standalone HPS is developed, integrating diverse power-generating units, variable loads, and electric vehicles (EVs) in grid-to-vehicle mode. Diesel engine generators (DEGs) provide backup support to stabilize grid operation and regulate frequency under fluctuating RES output. Two robust controllers are designed to regulate wind turbine blade pitch and DEG speed governors. Three control strategies proportional-integral-derivative (PID), three-degree-of-freedom PID (3DOF-PID), and fuzzy-3DOF-PID are implemented, with parameters optimized via a quasi-oppositional-based whale optimization algorithm. Comparative analysis reveals that the Fuzzy-3DOF-PID controller achieves superior performance, minimizing figure of demerit and improving dynamic response. Real-time validation using an OPAL-RT simulator confirms the practical feasibility of the proposed method. To evaluate scalability, the optimized controllers are applied to the IEEE 39-bus test system. Results show that the Fuzzy-3DOF-PID controller ensures effective frequency regulation under significant load variations and renewable intermittency while improving damping and stability margins. The study presents a robust, scalable LFC framework for RES-integrated HPS, enabling enhanced grid stability and supporting future smart grid applications.