Parasitic Boost Circuit For Transformer Less Active Voltage Quality Regulator With Closed Loop Controller

Abstract

Power Quality (PQ) problems have obtained increasing attentions as they can affect lots of sensitive end-users. Studies indicate that voltage sags, transients and momentary interruptions constitute 92% of all the PQ problems occurring in the distribution power system. Typical sag can be a drop between 10% and 90% of the rated rms voltage and has the duration time of 0.5 cycles to 1 min. According to the data presented, majority of the sags recorded are of depth no less than 50%, but deeper sags with long duration time obviously cannot be ignored as they are more intolerable than shallow and short-duration sags to the sensitive electrical consumers. The most studied voltage regulator topologies can be generally categorized into two groups the inverter-based regulator and direct AC–AC converters. Series-connected Devices (SD) are voltage-source inverter-based regulators and an SD compensate for voltage sags by injecting a missing voltage in series with the grid. A new design is proposed in order to compensate the voltage levels. High operation efficiency is obtained by this method of controlling due to application of the DC link voltage adaptive control method. Additionally, the proposed active voltage quality regulator is a cost effective solution for long duration sags that are lower than 50% of the nominal voltage as it is transformer less compared with the traditional dynamic voltage restorer.