A Thorough Examination of Harmonic Mitigation Techniques Through a Comparative Study of the UVT and PWM Methods within Power Systems

Abstract

Introduction: To mitigate the harmonic disturbances caused by non-linear loads, the selection of active power filters has emerged as a means to enhance filter efficiency and address numerous issues associated with traditional passive filters. A critical aspect of effectively implementing an active filter is the adoption of a robust method for generating current or voltage references. Various implementations, grounded in different theoretical frameworks (whether in the time or frequency domain), continuously evaluate their performance to provide increasingly effective solutions.

Objectives: This paper presents a comparative review of two distinct methods. Specifically, it examines the shunt active power filter, where the control strategies are based on the Unit Vector Template (UVT) and compares it with the Pulse Width Modulation (PWM) method.

Methods: SPWM modulation control method employs a single pulse for every half cycle, and the duration of this pulse is modified to control the output voltage of the inverter. Gating signals are generated by comparing a rectangular reference signal of amplitude Er with a triangular carrier wave of amplitude.

The basic system block diagram, showing the use of the UVT (Unit Vector Template) approach. The SAF acts as a component linked in series, successfully neutralizing the harmonic and reactive currents generated by a nonlinear load. As a result, the overall current taken from the primary AC source displays a sinusoidal pattern. In an ideal scenario, the Active Filter (AF) should generate only the required harmonic current to compensate for the nonlinear loads in the circuit.

ResultsThis report explores a method for reducing harmonics using the Shunt Active Filter (Shunt AF) to improve the quality of electric power at the distribution stage. The Shunt AF efficiently tackles the power quality issues linked to current from loads, such as reactive current, imbalance, harmonics, and neutral current.

Conclusions: Out of the two methods examined, the Unbalanced Voltage Technique (UVT) exhibits better results. When compared to other methods, the UVT method offers several advantages such as smaller switching losses, less memory utilization, reduced computing requirements, and much higher speed.