Power quality improvement through UPQC-P using multiple-enhanced Lyapunov-demodulated quadrature signal generator
摘要
This article proposes a generalized multiple-enhanced Lyapunov-demodulated quadrature signal generator (ELD-QSG) structure to control a unified power quality conditioner (UPQC) under grid and load disturbances. Conventional LD-QSG variants exhibit limited filtering capability, allowing lower-order harmonics to reside in the estimated peak signals. While a multiple LD-QSG structure improves estimation accuracy, it remains susceptible to DC offsets in the sensed source voltage or load currents, leading to oscillatory frequency behavior in peak estimates. To address this, a moving average filter (MAF) with a specific window length is incorporated into each harmonic extraction block , forming a generalized multiple ELD-QSG structure that effectively eliminates DC offset and enhances the accuracy of fundamental and harmonic peak estimation. The estimated signals are used to generate reference voltages and currents for compensation, while the amplitude of the fundamental voltage further supports phase angle detection for grid synchronization. The simulation results reveal that both LD-QSG and multiple LD-QSG structures contain