Utilizing UPQC-Based PAC-SRF Techniques to Mitigate Power Quality Issues under Non-Linear and Unbalanced Loads

Abstract

Power quality (PQ) has taken center stage in contemporary discussions owing to the escalating usage of power electronic gadgets. This paper throws light on the unified power quality conditioner (UPQC), an instrumental tool for load current balancing, voltage regulation, harmonics mitigation, sag and swell mitigation, and load-reactive power demand compensation within a three-phase, three-wire distribution structure catering to a variety of combinations of non-linear and unbalance loads. In scenarios devoid of UPQC, phenomena such as voltage sag, swell, and supply voltage distortion pose a potential threat to the sensitive equipment connected to the system. UPQC ingeniously amalgamates a series active power filter (APF) with a shunt APF, thereby addressing a majority of PQ issues. The control over the shunt APF is achieved via synchronous reference frame (SRF) theory, while the series APF is governed by the power angle control (PAC) technique. The application of SRF-PAC techniques manifests a high degree of robustness, effectively counterbalancing the VA loading imbalance in both series and shunt APFs within the UPQC system. This equilibrium is attained through the fair distribution of reactive load power between the two APFs. The simulation outcomes convincingly illustrate that UPQC minimizes the impact of supply voltage variations and harmonic currents on the power line under diverse loads, with the total harmonic distortion (THD) of load voltages and source currents generated being confined to less than 5%.