Knowledge Domain Control of AC/DC Hybrid Microgrid for EV Charging Application

Abstract

This paper presents a Knowledge Domain (KD)-based control framework for a DSTATCOM- integrated ac/dc hybrid microgrid designed for electric vehicle (EV) charging applications. The DSTATCOM, connected to the ac bus, regulates ac voltage and indirectly supports the dc bus via coordinated converter control. A small-signal model of the hybrid microgrid, including DSTATCOM dynamics, is developed to accurately capture system behavior and interactions among PV arrays, energy storage systems (ESS), EV loads, and grid-connected converters. The proposed KD control integrates offline optimization with near real-time adaptability to maintain stable EV charging under dynamically changing conditions. The controller parameters of the state feedback matrix (k) are optimized using Particle Swarm Optimization (PSO) by minimizing state deviations under perturbations via the Integral of Time-weighted Absolute Error (ITAE) criterion. The optimized parameters are stored in a KD database and mapped to operating conditions. During operation, the KD control framework rapidly retrieves appropriate parameters to update controller gains, ensuring fast damping and rapid stabilization under dynamical variations. System stability is evaluated through state perturbation analysis, where individual system states are perturbed to observe the impact on other states and verify proper settling with minimal undershoot/overshoot. A 10% dc bus voltage perturbation demonstrates that the system remains stable, with the DSTATCOM significantly reducing oscillations and settling time, which is further enhanced with PSO-tuned parameters. Experimental validation on the OPAL-RT OP4512 real-time simulator confirms the superiority of KD control over conventional PSO-tuned control, achieving faster damping, reduced settling time, and simultaneous regulation of ac and dc bus voltages. The proposed approach ensures robust microgrid operation, uninterrupted EV charging, and safe performance of interfaced converters under dynamic source and load variations. © 2013 IEEE.