Comparing the performance of IDVR for mitigating voltage sag and harmonics with VSI and CSI as its building blocks

Abstract

Power system is broadly divided into three stages, generation, transmission and distribution. There are several challenges in each stage which are needed to be addressed. This paper concentrates on the challenges in distributed systems called power quality. Power quality improvement is a major concern in the distributed system. There are several power quality problems like voltage sag, harmonics, flickering, distortions etc. Two major problems considered in this paper are the voltage sag and harmonics. To handle with these power quality problems Flexible AC Transmission Systems (FACTS) devices are utilized. Interline Dynamic Voltage Restorer (IDVR) is proposed to eliminate the voltage sag and harmonics. The major aspect of IDVR is being able to replenish energy to the DC link while injecting required voltage in more than one power line unlike the Dynamic Voltage Restorer (DVR). The building blocks of IDVR used for injecting the voltage can either be voltage source inverter (VSI) or current source inverter (CSI). An IEEE 8 bus system is considered, consisting of generation, transmission and distribution levels. The sensitive loads are assumed to be connected at the distribution side The IDVR is installed near the distribution side. The performance of the IDVR in reducing voltage sag and harmonics as its building block either VSI or CSI is investigated and compared in this paper in MATLAB environment.