Electrical energy storage systems

1. Introduction

Solar-electric-energy system has grown consistently over the years. The core of solar power generation system is a solar cell. Modeling the solar cell is required for study of photovoltaic systems.

Photovoltaic (PV) array which is composed of modules is considered as the fundamental power conversion unit of a PV generator system. The PV array has nonlinear characteristics and it is quite expensive and takes much time to get the operating curves of PV array under varying operating conditions. In order to overcome these obstacles, common and simple models of solar panel have been developed and integrated to many engineering software including Matlab/Simulink. However, these models are not adequate for application involving hybrid energy system since they need a flexible tuning of some parameters in the system and not easily understandable for readers to use by themselves. Therefore, this paper presents a step-by-step procedure for the simulation of PV cells/modules/ arrays with Tag tools in Matlab/Simulink. A DS-100M solar panel is used as reference model.

Energy storage systems play the important role of unifying, distributing and enhancing the capabilities of alternative and renewable energy-distributed generating systems. The storage systems are capable of smoothing out the load fluctuations as well as to react to fast transient power quality. In this manner they can contribute to efficient energy management policies and faster economic investments in the new projects.

The aim of this project is to realize a PV cell out of mathematical models and to obtain a charging state of a polymer electrolyte membrane fuel cell (PEMFC). All results will be realized in the Matlab/Simulink software using the power system library. Therefore, the study proposes a robust model built with tag tools in Simulink environment. The proposed model shows strength in investigating all parameters influence on solar PV array’s operation. In addition, a unique step-by- step modeling procedure shown allows readers to follow and simulate by themselves to do research based on the required application.

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2. Mathematical model for photovoltaic cell

The study proposes a robust model built with tag tools in Simulink environment. The model shows strength in investigating all parameters influence on solar PV operation. The step-by-step mathematical modeling procedure allows us to follow and simulate every part and to do research. The equivalent circuit of a PV cell is shown in Fig. 1. PV cell equivalent circuit The current source ????????ℎ represents the cell photocurrent. ????????ℎ and ???????? are the intrinsic shunt and series resistance of the cell. Usually the value of ????????ℎ is very large and that of ???????? is very small.

Fig. 1. PV cell equivalent circuit

A mathematical model of PV array including fundamental components of diode, current source, series resistor and parallel resistor is modeled with Tags in Simulink environment. In Fig. 2 is the caption of the input parameters used for modeling.

The simulation of solar module is based on equations given in the section above and done in the following steps.

Fig. 2. Input parameters for simulation model

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The photo-current equation of a solar cell is provided as the following:

[1]. L. Barote, “Electrical Energy Storage Systems Laboratory Handbook”, Brașov, Romania, 2013

[2]. Xuan Hieu Nguyen and Minh Phuong Nguyen, “Mathematical modeling of photovoltaic

cell/module/arrays with tags in Matlab/Simulink”, Department of Electric Power System, Faculty of Engineering, Vietnam National University of Agriculture, Trau Quy town, Gia Lam district, Hanoi 10000, Vietnam, 2015

[3]. Samer Said1, Ahmed Massoud, Mohieddine Benammar and Shehab Ahmed,

“A Matlab/Simulink-Based Photovoltaic Array Model Employing SimPowerSystems Toolbox”, Department of Electrical Engineering, Qatar University, Doha P.O. Box 2713, Qatar, 2012

[4]. K. Ishaque, Z. Salam et. al, “An Accurate MATLAB Simulink PV System Simulator Based on the Two-diode Model”, Journal of Power Electronics, vol. 11, no. 2, pp.179-187, 2011