Real-time implementation of advanced control strategies for parallel inverters and power flow management in hybrid microgrid for smart cities application

Hybrid microgrids (HMGs) have emerged as a critical framework for integrating renewable distributed generation, where the intermittency of sources such as solar PV necessitates robust energy storage and advanced control strategies. This paper proposes a high-performance hybrid controller that combines fuzzy logic with a fractional-order proportional–integral–derivative (FOPID) and conventional proportional–integral (PI) schemes for regulating a bidirectional DC–DC converter (BDC) interfaced with a battery energy storage (BES) system. The hybrid controller significantly enhances converter adaptability, optimises charge–discharge coordination, and ensures stable DC-link voltage under variable renewable energy conditions. To further strengthen microgrid stability, the study conducts a comprehensive evaluation of state-of-the-art grid-forming (GFM) inverter control strategies. Four GFM methods are investigated: droop control, virtual synchronous machine (VSM), standard virtual oscillator control (VOC), and two nonlinear oscillator-based extensions—dead-zone oscillator VOC (VOC-DZO) and Van der Pol oscillator VOC (VOC-VPO). Unlike droop and VSM techniques, which are reliant on phasor-based active and reactive power estimation, VOC methods utilise instantaneous current feedback, yielding superior transient and dynamic performance. The proposed control framework and inverter strategies are rigorously validated through extensive simulations in MATLAB/Simulink and real-time experiments on the OPAL-RT platform. Results demonstrate clear performance improvements in dynamic response, voltage regulation, and renewable energy utilisation, establishing the effectiveness of the hybrid control architecture for next-generation HMG applications.