Power Quality Improvement In Distribution Systems Using A Unified Power Quality Conditioner Based On A Pso-tuned Fractional Order Pi Controller

Abstract

The Increasing Penetration Of Nonlinear Loads, Power-electronic Converters And Intermittent Renewable Energy Sources Has Intensified Power Quality (PQ) Disturbances Such As Voltage Sag, Swell And Current Harmonics In Modern Distribution Networks. This Paper Presents The Design And MATLAB/Simulink-based Evaluation Of A Unified Power Quality Conditioner (UPQC) For Simultaneous Voltage- And Current-side Compensation, In Which The DC-link Voltage Regulation Loop Is Controlled By A Fractional Order Proportional-Integral (FOPI) Controller Whose Parameters (Kp, Ki, λ) Are Optimally Tuned Using Particle Swarm Optimization (PSO) With An Integral Of Time-weighted Absolute Error (ITAE) Fitness Function. Shunt Reference Currents Are Generated Using The Instantaneous P–q Theory In The Clarke–Park Reference Frame, While Series Reference Voltage Is Generated Using Unit-vector Templates; Both Inverters Are Switched Using Hysteresis Current Control. The Proposed Scheme Is Benchmarked Against An Uncompensated System, A UPQC With A Classical Ziegler–Nichols-tuned PI Controller, A UPQC With A PSO-tuned PI Controller, And A UPQC With An Empirically Tuned FOPI Controller, Under A Common Disturbance Profile Comprising A 0.7 P.u. Voltage Sag, A 1.3 P.u. Voltage Swell And Superimposed 5th/7th Order Harmonics Feeding A Three-phase Diode-bridge Rectifier Load. Simulation Results Show That The Source-current Total Harmonic Distortion (THD) Of 22.24% In The Uncompensated Case Is Reduced To 3.54% By The Proposed PSO-tuned FOPI-based UPQC, A Reduction Of 84.1%, Comfortably Satisfying The IEEE-519 Limit Of 5%, While Also Providing The Fastest DC-link Settling Time, The Lowest Overshoot, And The Most Effective Sag/swell Mitigation Among The Compared Strategies.

Keywords