Improving the voltage sag and voltage swell of power distribution with the integration of ultra-capacitor and dynamic voltage restorer using RBF network

Abstract

Power Quality (PQ) problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure of end use equipment’s. The voltage sag and swell are the most frequent PQ problems that mainly occur in the distribution systems that causes for frequent tripping of circuit breaker, 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 improving the voltage sag and swell. In this thesis, voltage sag and voltage swell problem are improved by using the method of integration of Ultra Capacitor and Dynamic Voltage Restorer device and Radial Basis Function network. Here, UCAP is used as energy storage as it provides excessive power in a short time interval. 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. RBF Controller was used in DVR for power quality enhancement. The simulation results have been carried out by MATLAB/Simulink. In the proposed system the voltage sag is compensated from 0.304 p. u to 1p.u and the voltage swell is compensated from 1.125p.u to 1p.u.