Page 5 - IJEEE-2023-Vol19-ISSUE-1

Received: 10 August 2022 Revised: 29 August 2022 Accepted: 02 September 2022
DOI: 10.37917/ijeee.19.1.1
Vol. 19| Issue 1| June 2023

Ð Open Access

Iraqi Journal for Electrical and Electronic Engineering

Original Article

Control Strategy for a PV-BESS-SC Hybrid System in
Islanded Microgrid

Ali Almousawi*1,2, Ammar A. Aldair1
1 Electrical Engineering Department, College of Engineering, University of Basrah, Iraq
2 Electrical Engineering Department, Faculty of Engineering, University of Kufa, Iraq

Correspondence
*Ali Q. Almousawi
Electrical Engineering Department
Faculty of Engineering, University of Kufa, Iraq
Email: ali.almousawi@uokufa.edu.iq

Abstract
In this paper, a control strategy for a combination PV-BESS-SC hybrid system in islanded microgrid with a DC load is designed
and analyzed using a new topology. Although Battery Energy Storage System (BESS) is employed to keep the DC bus voltage
stable; however, it has a high energy density and a low power density. On the other hand, the Supercapacitor (SC) has a low
energy density but a high-power density. As a result, combining a BESS and an SC is more efficient for power density and high
energy. Integrating the many sources is more complicated. In order to integrate the SC and BESS and deliver continuous power
to the load, a control strategy is required. A novel method for controlling the bus voltage and energy management will be
proposed in this paper. The main advantage of the proposed system is that throughout the operation, the State of Charging
(SOC), BESS current, and SC voltage and current are all kept within predetermined ranges. Additionally, SC balances fast-
changing power surges, while BESS balances slow-changing power surges. Therefore, it enhances the life span and minimizes
the current strains on BESS. To track the Maximum Power Point (MPP) or restrict power from the PV panel to the load, a
unidirectional boost converter is utilized. Two buck converters coupled in parallel with a boost converter are proposed to charge
the hybrid BESS-SC. Another two boost converters are used to manage the discharge operation of the BESS-SC storage in
order to reduce losses. The simulation results show that the proposed control technique for rapid changes in load demand and
PV generation is effective. In addition, the proposed technique control strategy is compared with a traditional control strategy.
KEYWORDS: Islanded Microgrid, Hybrid System, PV array, Autonomous Control.

I. INTRODUCTION Several researchers have presented strategies for
implementing a HESS.
Interconnections of Photovoltaic (PV) panels with In [9], the proposed technique is based on the analysis of the
supplemental energy sources which including Fuel Cell frequency of electric energy demand into low and high
(FC), wind turbine, or microturbine should solve the frequency components. Low-frequency components are
intermittency issue in the islanded Microgrid (MG) [1]. associated with elements that have a high energy density but
In addition, several techniques use storage rather than energy a low power density (BESS), while high-frequency
sources, such as Supercapacitors (SC) or Battery Energy components are associated with HESS elements that have a
Storage Systems (BESS). As a result, a PV-BESS or PV- low energy density but a high-power density (SC). The direct
BESS-SC hybrid system are created in order to manage the connection of the BESS in this study unavoidably exposes it
load and PV power generation by supplying/storing the to a rapidly rising charging/discharging current, reducing its
required/surplus loads power [2]. life span.
The BESS has a high energy density and a low power density In [10], the authors suggested an adaptive frequency
while the SC has a low energy density but a high-power technique as a new HESS power management approach for
density. Therefore, a Hybrid Energy Storage System (HESS) electric vehicles. A simpler digital adaptive filter was
combining SC and BESS becomes a common alternative for utilized in this technique to ensure solution convergence and
providing high power density as well as large energy to reduce the computational expense involved with real-time
capacity [3]. This application has been widely used in control. Using a half-bridge DC/DC converter, this power
tramways [4], electric vehicles [5], wind/PV power management method was successfully tested. In this study,
production systems [6], Fuel Cell ships [7], and DC MGs [8]. improved the efficiency only when the load is low.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and

reproduction in any medium, provided the original work is properly cited.

© 2022 The Authors. Published by Iraqi Journal for Electrical and Electronic Engineering by College of Engineering, University of Basrah.

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