Robust adaptive H-infinity based controller for islanded microgrid supplying non-linear and unbalanced loads

• Published in: IET Smart Grid Vol. 2; no. 3; pp. 420 - 435
• Main Authors: Sedhom, Bishoy E, Hatata, Ahmed Y, El-Saadawi, Magdi M, Abd-Raboh, El-Hosaini E
• Format: Journal Article
• Language: English
• Published: Durham The Institution of Engineering and Technology 01.09.2019; John Wiley & Sons, Inc; Wiley
• Subjects: Adaptive control; Adaptive systems; B8110C Power system control; B8120K Distributed power generation; C1310 Control system analysis and synthesis methods; C1320 Stability in control theory; C1330 Optimal control; C1340E Self‐adjusting control systems; C3110B Voltage control; C3110D Current control; C3110G Frequency control; C3340H Control of electric power systems; C7410B Power engineering computing; C7420 Control engineering computing; Communication; control engineering computing; Control methods; control system synthesis; Controllers; current error tracking; Distributed generation; distributed power generation; droop control loop; droop control method; Effectiveness; electric current control; Electric potential; fault clearance; frequency control; frequency regulation; Frequency variation; H-infinity controller; Infinity; Internal model principle; islanded microgrid; Load fluctuation; Matlab; nonlinear loads; off-grid mode; power distribution control; power engineering computing; power grids; power system stability; Repetitive control; repetitive control method; Research Article; robust adaptive H-infinity based controller; Robust control; Root locus; Simulink; Stability analysis; Step response; system load variation; system stability analysis; system step response; system voltage; Systems stability; Tracking control; unbalanced loads; Voltage; voltage control; voltage tracking; power distribution control; fault clearance; distributed power generation; Simulink; electric current control; repetitive control method; system step response; droop control loop; system load variation; system stability analysis; droop control method; robust adaptive H-infinity based controller; robust control; power grids; system voltage; control engineering computing; islanded microgrid; voltage tracking; power system stability; off-grid mode; control system synthesis; adaptive control; frequency control; unbalanced loads; current error tracking; frequency regulation; power engineering computing; root locus; internal model principle; H-infinity controller; nonlinear loads; voltage control; Matlab
• ISSN: 2515-2947; 2515-2947
• DOI: 10.1049/iet-stg.2019.0024

This study introduces a proposed control method for microgrids (MGs) in islanded (off-grid) mode. The proposed control method is developed by modifying the droop control method using H-infinity controller. In this control method, the droop control loop, current and voltage control loops are adjusted to respond to system load variation. The proposed method is an adaptive control one as it regulates the system voltage and frequency to their nominal values after system load variations. Also, it is a repetitive control method as it depends on the internal model principle that provides good performance for voltage and current error tracking. To prove the applicability and effectiveness of the proposed method, it is applied to a test system using MATLAB/Simulink under three different loading conditions. The results are compared with those of droop control and they prove the effectiveness of the proposed method in adjusting MGs under the off-grid mode of operation. Also, a system stability analysis is performed based on root locus and system step response. Robustness analysis is performed to prove the ability of the proposed controller to restore the system performance after the fault clearance.