Controller-in-the-Loop Validation of an Industrial Power Plant Controller for Utility-Scale Hybrid PV–Wind–BESS Plants

The increasing penetration of renewable energy sources and converter-interfaced generators requires rigorous validation of power plant controllers to ensure grid-code compliance and stable operation. This paper presents a CiL test system for validating a redundant PLC-based PPC developed for an actual utility-scale hybrid PV–wind–BESS power plant. To the best of the authors’ knowledge, this represents one of the first CiL-based pre-commissioning validation frameworks specifically developed for an industrial PPC of such a plant. The proposed framework integrates a MATLAB/Simulink plant model with the physical PLC-based PPC through MODBUS TCP for closed-loop signal exchange and MQTT for SCADA integration. The PPC validates key grid-code and plant-level functions, including active power limiting, ramp-rate control, FSM, LFSM-O, LFSM-U, constant reactive power control, voltage regulation, and constant power factor control. A time-compression method is also used to reproduce 24 h operating scenarios within 240 s simulation windows while preserving SCADA schedule consistency. Validation using real 24 h plant data confirms enforcement of the 172.2 MW connection limit through coordinated BESS operation and renewable curtailment, with stable active and reactive power responses. The proposed CiL framework reduces commissioning risk and supports reliable hybrid power plant integration.