Enhanced UPQC Control Scheme for Power Quality Improvement in Wave Energy Driven PMSG System

This article focuses on enhancing power quality (PQ) in a wave energy-driven permanent magnet synchronous generator (PMSG) system with unbalanced and highly inductive nonlinear loads using a unified power quality conditioner (UPQC). Our proposed control system improves voltage quality, compensates for reactive power, and mitigates harmonics. It ensures constant voltage amplitudes during supply voltage faults, achieving harmonic rejection, reactive power compensation, and enhanced voltage quality through the UPQC's parallel converter. Compared to previous methods, we introduce a frequency-fixed second-order generalized integrator (FFSOGI) quasi-type-1 PLL for efficient load harmonics extraction and source voltage fault detection. Additionally, a robust nonlinear proportional-integral (N-PI) controller, with a feedforward term, regulates the DC-link voltage swiftly and mitigates fluctuations. Our approach ensures compliance with IEEE standards for source current and load voltage harmonics. Comprehensive PSCAD/EMTDC results, utilizing experimental torque and power data from a wave energy converter at the Australian Maritime College model test pool, highlight the advantages of our proposed approach over conventional methods.