Power quality improvement using dynamic voltage restorer and interline power flow controller

Abstract

This work deals with power quality improvement using Dynamic Voltage Restorer (DVR) and Interline Power Flow Controller (IPFC) systems. The Dynamic Voltage Restorer as a means of series compensation for mitigating the effect of voltage sag and well, has become established as a preferred approach for improving power quality at sensitive load locations. The Interline Dynamic Voltage Restorer (IDVR) provides a way to replenish the DC link energy storage dynamically. The IDVR consists of several DVRs connected to different distribution feeders in the power system. The DVRs in the IDVR system share common energy storage. When one of the DVRs compensates the voltage sag appearing in that feeder, the other DVRs replenish the energy in the common DC link dynamically. In principle, the IDVR can operate effectively when the constituent DVRs are electrically far apart. The IDVR is modeled and the corresponding simulation results are presented. A technique based on the SVPWM to generate the pulses is also presented. The Interline Power Flow Controller is a Voltage Source Converter (VSC) based Flexible AC Transmission System (FACTS) controller for series compensation with the unique capability of power flow management among the multiline transmission systems of a substation. The reactive voltage injected by the individual VSC can be controlled to regulate the active power flow in the respective line. While one VSC regulates the DC voltage, the other one controls the reactive power flows in the lines by injecting series active voltage. A dispatch strategy is proposed for an IPFC operating at rated capacity, in which the power circulation between the two series converters is used as the parameter to optimize the voltage profile and power transfer. Voltage stability curves for the test system are shown to illustrate the effectiveness of this proposed strategy. A circuit model for the IPFC is developed, and simulation studies of the IPFC are done using MATLAB simulink.