Power quality improvement of distribution power networks using capacitor-less H-bridge inverters for voltage regulation

These days FACTS devices are predominantly used to improve the power quality in distribution networks to meet the standards. The dynamic voltage restorer (DVR) plays a vital role in maintaining voltage in a distribution power substation at standard levels. DVRs can compensate a short period of sag or swell in a power network. Currently, many industries employ a servo-controlled voltage stabilizer at their premises to compensate voltage fluctuations and swells that occur for a longer period of time. Servo-controlled voltage stabilizers take about 20–30 power cycles to compensate fluctuation. The operation of sensitive equipment fails due to this inefficient compensation. This paper presents a solution for both voltage fluctuations and prolonged low voltage profiles at distribution networks. The proposed switching algorithm for the H-bridge inverter compensates grid voltage fluctuations by injecting compensating voltage without utilizing a DC bulk capacitor unlike a DVR. A prototype developed in the laboratory is tested experimentally and the obtained test results verify the extended feature of the proposed solution.