Robust Centralized Control for DC Islanded Microgrid Considering Communication Network Delay

Muhammad Mehdi,Chul-Hwan Kim,Muhammad Saad

doi:10.1109/access.2020.2989777

Muhammad Mehdi, Chul-Hwan Kim + Show 1 more

Open Access

https://doi.org/10.1109/access.2020.2989777

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Abstract

In recent years, the application of renewable energy resources (RES) with DC output has increased, and RES integration as DC islanded microgrids (DC ImGs) has attracted the attention of many researchers. However, DC ImGs face many challenges, and voltage stability is extremely critical for efficient power distribution. This challenge becomes more prominent when exogenous disturbances, as well as time-delay, exist in the system mainly because of the communication network. In this study, we develop a mathematical model of the time-delay DC ImG. To compensate for the effect of the time-delay, three control strategies are introduced-stabilizing, robust, and robust-predictor. The controller's stability is guaranteed based on the Lyapunov-Krasovskii theorem, whereas for the exogenous disturbance rejection, the $\mathcal {L}_{2}$ -norm of the system is reduced. Furthermore, to obtain the proposed controllers' gains, linear-matrix-inequality constraints are formulated. The performances of the controllers are investigated through numerous simulations, and a detailed analysis is presented.

Highlights

The increasing use of DC loads and penetration of DC distributed generation units (DGUs) have attracted the attention of researchers worldwide [1], [2]
We present the dynamical representation of the DC islanded microgrids (DC ImGs) with communication delay
The control gains for the controller are obtained by solving the respective LMIs discussed in the last section using the YALMIP toolbox in MATLAB and Mosek as a solver [49], [50]

Summary

Introduction

The increasing use of DC loads and penetration of DC distributed generation units (DGUs) have attracted the attention of researchers worldwide [1], [2]. In the recent years, the development of DC distribution systems and DC Microgrids [3] has attracted increasing attention. The integration of DC DGUs or sources to DC loads has several benefits. The two pronounced advantages are no requirement for synchronization and elimination of the DC/AC-AC/DC conversion losses between sources and loads [3]. Other benefits associated with the DC system are the absence of harmonics and reactive power flow controls. The DC system is more economical in comparison with its AC counterpart [4], [5]

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