IMPROVING VOLTAGE SAG AND VOLTAGE SWELL OF DISTRIBUTION SYSTEM WITH INTEGRATION OF ULTRA CAPACITOR AND DYNAMIC VOLTAGE RESTORER

Abstract

Power Quality (PQ) problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure of end use equipments. The supply status of electrical services required for case study of Agro Processing Industry illustrates this concept. The voltage sag and swell are the most frequent PQ problems that mainly occur in the distribution systems because of it causes circuit breaker tripping, failure of drive systems, shutdown for domestic and industrial equipment. The Dynamic Voltage Restorer (DVR) connected in series has magnificent dynamic capabilities and is a flexible solution for PQ problems. Ultra-Capacitors (UCAP) has ideal characteristics such as high power and low energy density essential for the mitigation of voltage sag and swell. In this proposed research voltage sag and voltage swell problem are improved by using the method of integration of Ultra Capacitor and Dynamic Voltage Restorer device. In this study UCAP was used as energy storage as it provides excessive power in a short time interval of time. Integrated DVR into Ultra Capacitor via bidirectional DC-DC converter which supports in presenting a rigid dc-link voltage and helps in compensating temporary voltage sag and voltage swell. The integrated UCAP-DVR is implemented at low voltage side of distribution transformer. PI Controller was used in DVR for power quality enhancement. The simulation results carried out by Matlab/Simulink verify the performance of the proposed method. In the proposed system the voltage sag is mitigated from 0.304 p.u to 1p.u and the voltage swell is compensated from 1.125p.u to 1p.u