Abstract

Three-phase inverters are widely used in grid-connected renewable energy systems. This paper presents a new control methodology for grid-connected inverters using an adaptive fuzzy control (AFC) technique. The implementation of the proposed controller does not need prior knowledge of the system mathematical model. The capabilities of the fuzzy system in approximating the nonlinear functions of the grid-connected inverter system are exploited to design the controller. The proposed controller is capable to achieve the control objectives in the presence of both parametric and modelling uncertainties. The control objectives are to regulate the grid power factor and the dc output voltage of the photovoltaic systems. The closed-loop system stability and the updating laws of the controller parameters are determined via Lyapunov analysis. The proposed controller is simulated under different system disturbances, parameters, and modelling uncertainties to validate the effectiveness of the designed controller. For evaluation, the proposed controller is compared with conventional proportional-integral (PI) controller and Takagi–Sugeno–Kang-type probabilistic fuzzy neural network controller (TSKPFNN). The results demonstrated that the proposed AFC showed better performance in terms of response and reduced fluctuations compared to conventional PI controllers and TSKPFNN controllers.

Highlights

  • Nowadays, renewable energy sources (RES) such as photovoltaic (PV) solar systems, wind turbines, and others are integrated into conventional power systems to avoid the high cost of constructing new or expanded facilities [1]

  • Many maximum power point tracking (MPPT) techniques have been reported for PV systems, in practice, the most commonly used methods are perturb and observe (P&O) and the incremental conductance (IC) techniques [45]

  • The developed troller relies on two principles: namely, the input-output feedback linearization principle controller relies on two principles: namely, the input-output feedback linearization prinand the approximation capability of the fuzzy system

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Summary

Introduction

Renewable energy sources (RES) such as photovoltaic (PV) solar systems, wind turbines, and others are integrated into conventional power systems to avoid the high cost of constructing new or expanded facilities [1]. Non-linear controllers for grid-connected inverter systems (GCIS) such as sliding mode, feedback linearization, and hysteresis controllers have been proposed in [9,10,11,12,13]. A fuzzy neural network controller based on the Takagi–Sugeno–Kang type approach presented to control the active and reactive power of three-phase grid-connected. To the best of the authors’ knowledge, there is no reported work available that describe the application of AFC to the GCIS This motivates the authors to propose an AFC scheme that exploits the concept of the multi-input multi-output (MIMO) feedback linearization and the approximation capability of fuzzy systems. The proposed AFC, based on the method of feedback linearization, is developed to solve these nonlinearities and uncertainties due to the method’s ability to manage complex nonlinear control systems without the need for a mathematical model.

Grid-Connected
Simulation results are inshould
Three-phase
MIMO Model of GCIS
Input-Output Feedback Linearization of GCIS
Adaptive Fuzzy Approximation Controller for GCIS
Closed-Loop Stability
Implementation of the Proposed Adaptive Fuzzy Controller for GCIS
Simulation Cases and Results
Case I
Case II
Grid current
Case III
13. Figure illustrates the bounded
14. Control signals increase in
16. For thesame case time of thewith
Case IV
Conclusions
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