DVR Using Diode Clamped Multilevel Inverter with Multicarrier Based Pulse Width Modulation Technique

The Quality of the output power from the utilities has become a major concern of the modern industries. These power quality associated problems are voltage sag, surge, flicker, voltage imbalance, interruptions and harmonic problems. These power quality problems may cause problems to the industries ranging from malfunctioning of equipment to complete plant shut down. It has been identified that power quality can be degraded both due to utility side abnormalities as well as the customer side abnormalities. Voltage sag and swells in the medium and low voltage distribution grid are considered to be the most frequent type of power quality problems based on recent power quality studies. Their impact on sensitive loads is severe. Different solutions have been developed to protect sensitive loads against such disturbances but Dynamic Voltage Restorer (DVR) is considered to be the most efficient and effective solution. In this project, Dynamic Voltage Restorer (DVR) is implemented using fifteen level diode clamped multilevel inverter with Phase Opposition Disposition (POD) and Alternate phase opposition disposition pulse width modulation(APOD). In POD technique, four carrier waveforms are arranged so that all carrier waveforms above zero are in phase and they are 180 degrees out of phase with those below zero. In APOD technique, Carriers are arranged in such a manner that each carrier is out of phase with its neighbor by 180 degrees. The gate signals for the chosen inverter can be derived directly from the PWM signals .This is the difference between the POD and APOD multi carrier PWM technique. The main aim is to reduce the harmonic distortion and to mitigate the voltage sag. Thus the Power quality of the proposed system is expected to improve. Simulations are carried out using MATLAB/SIMULINK to verify the performance of the proposed method.