Real-Time Implementation and Testing of a Wavelet-Controlled Dynamic Voltage Restorer

Abstract

This paper presents an experimental testing of a discrete wavelet transform (DWT)-controlled dynamic voltage restorer (DVR) system for power quality improvement. The proposed DWT-operated DVR system is designed to continuously detect, diagnose and respond to different transient disturbances that may affect the power quality. The input voltage to the proposed DVR system is adjusted by approximation signals to ensure transient-free inputs. Also, the output of the proposed DVR is obtained using a dc-ac inverter, whose switching signals are controlled by a detail signal. Both approximation and detail signals are obtained using DWT of the line voltage. An experimental setup for the proposed DWT-controlled DVR system is constructed, where the DWT is implemented using a dSPACE ds1102 digital signal processing board. Moreover, sinusoidal pulse-width modulation switching signals for the output-end dc-ac inverter are generated using the same DSP board. In this paper, the proposed DVR system is experimentally tested for transient voltage dip, steady-state under voltage and transient harmonic distortion cases. Test results for these cases show accurate, fast and effective DVR system responses. In all tested cases, the load voltage is maintained at its predefined nominal value during and post any abnormal conditions, which validate the proposed operating strategy.