Model predictive Control of D-STATCOM with chopper based voltage balancing technique and grey wolf optimisation

This paper presents an integrated control strategy for a three-phase Distribution Static Compensator (D-STATCOM) combining Model Predictive Control (MPC), a chopper-based DC-link voltage balancing technique, and Grey Wolf Optimization (GWO)-based PI tuning. The control architecture consists of an inner MPC current controller for fast dynamic response and constraint handling, and an outer PI voltage controller responsible for maintaining the DC-link reference voltage at the Point of Common Coupling (PCC). The PI controller gains are optimally tuned using GWO by minimising the Integral of Time-weighted Absolute Error (ITAE) of the DC-link voltage error. A chopper circuit is incorporated to balance the split DC-link capacitor voltages, operating independently from the MPC and PI loops to ensure symmetrical voltage distribution under dynamic and unbalanced load conditions. MATLAB/Simulink results demonstrate improved PCC voltage regulation, enhanced transient response, and superior DC-link voltage balancing compared to conventional control schemes.