Cascaded Multilevel Inverter Type Distribution STATCOM for Power Quality Improvement

In energy transmission systems, effective equipments on power control are generally known as Flexible AC Transmission System (FACTS). In addition, the power electronics-based equipment, which are called power conditioners are use to solve power quality problems. Since the topologies of these equipments are similar to those used in FACTS equipment, power conditioners are also called Distribution FACTS (DFACTS). DSTATCOM is one such power conditioner used for improving power quality. This study proposes a cascaded multilevel inverter type DSTATCOM to compensate voltage sags in utility voltages in power distribution network. The proposed DSTATCOM is implemented using multilevel topology with isolated dc energy storage. The phase shifted PWM and Inverted sine carrier PWM techniques are described to generate firing pulses to cascaded inverter and a comparison is made between the two techniques. The proposed controller adopts itself to the sag and swell provides effective means of mitigating the voltage with the minimum harmonics at the utility end. The proposed concept will be simulated using MATLAB Simulink environment. The Simulink results will be presented to verify the performance of the proposed multilevel DSTATCOM.