Real-time Simulations on Ultracapacitor based UPQC for the Power Quality Improvement in the Microgrid

Penetration of renewable energy systems (RES) into microgrid (MG) increases rapidly due to the intensified energy demands by the distribution level consumers. To meet this demand, consumers are erecting small scale distribution renewable energy generating systems (DREGS) which mostly constitutes of solar photovoltaic systems. Injecting power from the DREGS to the MG will rise potential problems like real and reactive power distortions, sag/swells which affect the power quality of the system. Voltage sags and swells are normally caused by MG intermittencies which occur at the high power and low energy situations. In order to maintain the power quality of the MG during intermittencies, an ultracapacitor (UC) is integrated along with a unified power quality conditioner (UPQC) with the DREGS is proposed in this paper. Basically, an ultracapacitor is a high power and low energy density device that will compensate the MG intermittencies. This proposed system deals with the control and design aspects of the ultracapacitor, a bidirectional converter for charging and discharging of UC, and a UPQC. The UPQC will act as a dynamic voltage restorer (DVR) for the MG side and an active power filter (APF) for the load side. The proposed system is designed and modelled using Matlab/Simulink platform and the results were analyzed.