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Abstract
A new approach for power line conditioning has been presented in this dissertation. Prevalent state of the art line-conditioning devices like Static Voltage Restorer (SVR), Dynamic Voltage Restorer (DVR) and AC-AC power line conditioner offers higher bandwidth and low filter size requirement due to their high switching frequencies. However, commercial utilization of such devices is restricted by voltage blocking capability of power semiconductor switches employed in these converters. Recent literature reports a Center-Point-Clamped AC-AC Converter topology based on Neutral-Point Clamped DC-AC inverter, where the grid voltage is clamped to its midpoint to reduce the voltage stress on the bi-directional switches employed in the converter by 50%. This document introduces a Power Line Conditioner based on Center-Point-Clamped AC-AC Converter topology, where the grid voltage is clamped to its midpoint to reduce the voltage stress on the bi-directional switches employed in the converter to half the summation of grid input and load output voltage. This power line conditioner is coined as Center-Point-Clamped Power Line Conditioner (CPC PLC). A duty cycle control scheme has also been implemented for feedback control of CPC PLC. An experimental prototype has been built in the laboratory. The results verify that proposed CPC PLC offers reduced voltage stress on the bi-directional switches. It may also be that CPC PLC is capable of mitigating grid voltage sag up to 90% and grid voltage swell up to 10%, which comprise of about 74% of the grid power quality issues. Furthermore, these results verify that the designed duty-cycle based control scheme has excellent load voltage regulation under dynamic line voltage conditions.