Design and Implementation of a Robust Current Controller for Single-Phase Inverters Connected Electrical Network via a damped LCL filter for Renewable Energy Systems J. A. Borges, M. V. B. Mendonça, F. A. M. Moura, M. R. M. C. Albertini 2018/04/20

Abstract

A renewable energy source plays an important role in electricity generation. Various renewable energy sources like wind, solar, geothermal, ocean thermal, and biomass can be used for generation of electricity and for meeting our daily energy needs. Energy from the sun is the best option for electricity generation as it is available everywhere and is free to harness. This paper deals with the design and implementation of a current controller for a single-phase voltage-fed inverter connected via an LCL filter. In this proposal, a single-phase micro-inverter connected to the power grid based on a complete bridge topology and the effects presented by the inclusion of a notch filter in the external voltage control mesh were analyzed. The proposed control improves the harmonic rejection capacity of the single phase inverters connected to the electric grid for application in photovoltaic panels, which is based on an alternative control structure and the proper selection of the LCL filter feedback current. The inclusion of a high order filter such as LCL in place of the traditional inductive filter provided greater capacity and attenuation of the unwanted components. However, the resonance from this filter impairs the stability of the system, requiring the inclusion of passive or active damping techniques. With the notch filter acting on the system, the current injected into the network had a substantially better total harmonic distortion index (THD), mainly due to the elimination of the 120 Hz ripple, meeting the requirements of international standards such as IEEE 1547.
In addition, the control of the system proved to be robust and efficient, keeping the steady state error close to zero even in the event of voltage sinking and variations in the frequency of the network.

Authors and affiliations

J. A. Borges(1), M. V. B. Mendonça(2) , F. A. M. Moura(2), M. R. M. C. Albertini(2)
1. Universidade Federal de Uberlandia, Electrical Engineering Department Uberlandia- Minas Gerais, Brazil,
2. Universidade Federal do Triângulo Mineiro, Electrical Engineering Department, Uberaba- Minas Gerais, Brazil

Key words

Electric power. Harmonic distortion. Imbalance. Quality electricity. Renewable energies. photovoltaic system.

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