A Simplified Design Strategy for Multi-Resonant Current Control of a Grid-Connected Voltage Source Inverter with an LCL Filter

Matthias Schiesser,Mario Marchesoni,Sébastien Wasterlain,Mauro Carpita

doi:10.3390/en11030609

Abstract

A distorted grid voltage or nonlinear behavior in the current control loop can cause low frequency current harmonics in a grid-connected voltage source inverter (VSI). Many efforts have been made to mitigate such phenomena, including hardware and/or control structure improvements. A well-known suitable strategy to reduce current harmonics in a selective manner is to apply a Proportional Multi-Resonant (PMR) current controller. Inverter-grid stability is another common issue when dealing with grid-connected VSI. Stability is influenced by the inverter impedance, which depends on the controller parameters. This paper presents a simplified tuning strategy for the PMR controller, taking into consideration the inverter-grid stability issue. The obtained controller was implemented and tested in a 10 kW three-phase inverter with a passively damped LCL filter. A significant reduction of current harmonics emission from the inverter up to 650 Hz was achieved without any hardware modification. The limits of PMR controllers to mitigate current harmonics were studied, and the influence of the grid impedance was verified.

Highlights

Distributed energy generation is increasing with the exploitation of renewable energy sources.Current-controlled voltage source inverters (VSIs) are commonly used to connect those sources to the AC utility grid
Low frequency harmonics exist as a consequence of nonlinear behavior in the current control loop such as the switching dead time [2], grid voltage disturbances [1,3], and DC-link voltage harmonics [3]
This paper focuses on low frequency current harmonics mitigation for a three-phase, three-wire inverter with a passively damped LCL filter, without any hardware intervention

Summary

Introduction

Distributed energy generation is increasing with the exploitation of renewable energy sources.Current-controlled voltage source inverters (VSIs) are commonly used to connect those sources to the AC utility grid. Passive or active output filters are used to reduce these perturbations in the kHz range [1].

Objectives

Results

Conclusion