Total Harmonic Distortion Reduction in a Power Grid: A UPQC Based Approach

This study shows a novel design for a unified power quality conditioner (UPQC) to improve the power quality. The designed UPQC has two active power filters (APF) in shunt and series combinations. PWM (pulse width modulation) and hysteresis controls are the two control mechanisms used in this study. To reduce harmonics, a direct-quadrature zero (dq0) conversion is performed. In case 1, for a single-bus system, the total harmonic distortion (THD) of the source current in the system without UPQC was 22.22%. After applying the designed method, THD has been reduced significantly to 2.68%. In case 2, for multi-bus systems, the THD was 20.62% and 5.05% with and without the UPQC, respectively. Here the THD in the grid input voltage was 20.62%, whereas the output voltage was 0.80%. The IEEE 519–2014 standard for voltage and current harmonics distortion criterion for electrical system design is followed in the research.