Reducing the Voltage Sag and Swell Problem in Distribution System Using Dynamic Voltage Restorer with PI Controller

One of the major problems observed in distribution system in recent days is Power Quality. Today most of the people are using the sophisticated electrical equipment based on semiconductor device, these equipment pollute the power quality. The sag and swell problem not only occur by the disturbed power quality but also due to high system tapping at the point of common coupling in the system. The non linear load is also creating the same problem at the load end. The Dynamic Voltage Restorer is recognized as the best solution for mitigation of voltage sag and swell associated problems in the highly taped distribution system. This work presents the simulation modeling and analysis of advanced DVR system for solving these problems. The PI control scheme is used for generating the gate pulse for IGBT bridge converter. The reference DC voltages are taken from the battery. The three phase fault is creating in the system and for analyzing the result. The role of DVR is to compensate the load current and voltage is investigated during the fault condition. Over all the DVR is improving the voltage quality as well as the reactive power demand during the uncharacteristic condition Index Terms— Voltage sag, swell, DVR, PI controller, LC filter The DVR is a series conditioner based on a pulse width modulated (PWM) voltage source inverter (VSI), which could generate or absorb real or reactive power independently. The condition of Voltage sags caused by unsymmetrical line to line, single line to ground (SLG), double line to ground fault and symmetrical three phase faults is, influenced in case of sensitive loads. The DVR injects the individual voltages to restore and maintained sensitive loads to its nominal value. The combination of the custom power devices DVR with PI controller for the power quality improvement in the distribution system. Here linear load are considered, only when different fault conditions are measured with these loads to analyze the operation of DVR to improve the power quality in distribution system. A new control strategy has been developed for achieving maximum benefits by eliminating or mitigating voltage sag / swell and power quality problem when abnormal condition occur in the distribution system, for this purpose the dynamic voltage restorer is proposed to improve the power quality and to reduce the sag and swell problem in the system. The DC link capacitor clamped converter is connected with series through transformer. We have proposed that if DC source is integrated with grid, with developing adequate control of grid-interfacing inverter, all objectives can be accomplished either individually or simultaneously. We have implemented the features of DVR for maximum utilization of distribution voltage, which are not fully utilized due to intermittent nature of distribution voltage because our system was highly tapped.