Control of DVR using Variable Step-Size Griffith's LMS with Optimized tuning of Proportional Integrator Gains

This paper deals with Dynamic Voltage Restorer (DVR) with a topology having three single phase H-Bridge voltage source converters (VSCs). The Power Quality (PQ) issues addressed by DVR with this topology are sag, swell, imbalances, and distortions in supply voltage. This topology has the advantage of allowing the reduced rating of DC-bus capacitor. The control that is proposed for operation of DVR to compensate the aforesaid PQ issues is VSG-LMS. VSG-LMS stands for Variable Step-size Griffith's Least Mean Square, named after Griffiths cross correlation concept has been added which is free from observation noise concept. Also the step size in this algorithm is dynamically variable using the Okello's variable step size algorithm. This control algorithm contains two Proportional and Integral (PI) controllers for maintaining the DC-link voltage and load terminal voltage respectively. The gains of these error regulators are tuned using Dragonfly based Optimization (DFO) technique. The main advantage of this technique is that the characteristics of optimization algorithms exploration and exploitation which improves the optimization process are achieved by the static and dynamic behaviors of dragon. After compensation of PQ issues listed above, the simulation result have been presented in this paper to evaluate the proposed control algorithm on the DVR.