Self-tuned Adaptation Rate Lyapunov based Voltage Controller for a Grid Connected PV System

Abstract

This paper proposes a novel Self-tuned Adaptation gain enable Lyapunov Based Adaptive Controller (STLBAC) for three-phase Grid-Tied PV System (GTPVS). There are numbers of influencing factors for achieving PV voltages tracking such as intermittent solar irradiance, aging of DC link capacitor. To accomplish better performance of GTPVS in presence of uncertainties in irradiance and DC-link capacitor, a STLBAC is proposed to regulate the PV panel voltage. An adaptation mechanism is designed by using Lyapunov theory to adjust gains such that the desired PV voltage tracking response can be achieved despite the uncertainties. The performances of the proposed STLBAC are verified by using simulation and experimentation on a 2 kW GTPVS. The efficacy of the proposed STLBAC has been compared with Robust Nonlinear Adaptive Backsteeping Controller (RNBC). It is found that the STLBAC provides better PV voltage tracking with less voltage ripple. Also, the grid current THD yielded by STLBAC is less as compared to RNBC. The PV voltage tracking found critically damped with desired settling time (i.e., 20 ms). The grid currents and grid voltages Total Harmonics Distortion (THD) are found as 2.1 % and 2 % respectively which are within the limit of IEEE-1547 standard.