Advancing microgrid power quality: integration of GRU-based control in PV-UPQC systems

This study proposes an innovative approach to enhance the performance of photovoltaic-unified power quality conditioner (PV-UPQC) system by replacing traditional synchronous reference frame control with a sophisticated gated recurrent unit (GRU) network controller. This innovative framework achieves a reduction in system expenditure and intricacy by neglecting mathematical operations. The GRU-based controller dynamically adjusts voltage source converter control signals, effectively mitigating voltage irregularities caused by nonlinear loads and harmonic supply voltages, thus improving overall power quality (PQ). The GRU's proficiency in retaining and adopting historical information renders it well-suited for managing the dynamic and time-varying attributes inherent in power systems. Moreover, a prairie dog optimized adaptive neuro-fuzzy inference system controller is employed for precise DC bus voltage regulation. The PV-UPQC system is reinforced by both PV and battery energy storage system (BESS) support, enhancing reliability and sustainability in grid-connected microgrids. In typical scenarios, PV furnishes active power to the load, seamlessly transitioning to BESS during prolonged voltage interruptions. In contrast to stand-alone PV-UPQC systems, the hybrid PV-BESS configuration ensures heightened reliability, alleviating instability and environmental dependencies. A comprehensive evaluation of this proposed approach, conducted through MATLAB simulations and validated experimentally, substantiates its effectiveness in advancing PQ, reliability and sustainability by generating a reduced settling time of 0.18 s, simulation THD of 0.60% and hardware THD of 1.22%. Moreover, the proposed work exhibits an improved power factor of 0.999 with enhanced dynamic response and reduced complexity.