This paper proposes a novel method for the generalized controller design of a three-phase LCL-filter-based grid-connected inverter system that can address deviations in system parameters. An optimum way to determine the stability bounds under various system parameters cases is introduced. | Journal of Scıence and Technology 54 (3A) (2016) 39-51 A NOVEL METHOD FOR DESIGNING THE CONTROLLER OF A LCL-FILTER-BASED GRID-CONNECTED INVERTER WITH CONSIDERING VARYING SYSTEM PARAMETERS Nguyen Trung Nhan1, *, Nguyen Thi Hanh2 1 Faculty of Electrical Engineering, Industrial University of Ho Chi Minh City, 12 Nguyen Van Bao St, Ward 4, Go Vap Dist, Ho Chi Minh City, Viet Nam 2 Faculty of Information Technology, Industrial University of Ho Chi Minh City, 12 Nguyen Van Bao St, Ward 4, Go Vap Dist, Ho Chi Minh City, Viet Nam * Email: nguyentrungnhan@ Received: 15 June 2015; Accepted for publication: 26 July 2016 ABSTRACT Exactly determining the control coefficients for the controller of a three-phase LCL-filterbased inverter is an important and challenging issue in microgrid systems. However, existing LCL-filter-based inverter systems usually assume that all system parameters are determined accurately and remain constant over time, which is not true in real situations. Variations in the system parameters are known to possibly seriously degrade the performance of LCL-filter-based inverter systems. For efficiency and robustness, this paper proposes a novel method for the generalized controller design of a three-phase LCL-filter-based grid-connected inverter system that can address deviations in system parameters. An optimum way to determine the stability bounds under various system parameters cases is introduced. The assessment of the stability bounds is based on the Routh criterion by solving the characteristic equation of the closed-loop control system. Simulations results are presented to validate the correctness and effectiveness of the proposed design method. Keywords: LCL filter, stability criterion, control quality, renewable energy resources. 1. INTRODUCTION In recent years, penetration of renewable energy resources-based distributed generations (DGs) into the power grid is increasing worldwide at a significant rate. This is an .
