# Performance Analysis of a PEMFC-Based Grid-Connected Distributed Generation System
## 3 Overview of Hybrid Microgrid System  
The proposed DG system is established in Marmara University, Faculty of Technology, Istanbul, Turkey. With this system, university researchers and academicians will be supported in the fields of fuel cell technologies, renewable energy systems, power electronics, sustainable energy management, energy managements systems, and hybrid power systems. The aforementioned components of the DG system are shown in Figure 1 and are as follows: four pieces of PV panels (250 W) exist and create PV modules that are 1000 W rated power. A horizontal axis wind turbine has a 400 W output power with a permanent magnet synchronous machine (PMSM) as a generator. A PEMFC stack operates with a hydrogen generator (electrolytezer) with a 60 sL/h H\({}_{2}\) flow, which gives 1200 W output power. To provide H\({}_{2}\) to the stack, a low-pressure metal hydride hydrogen tank with 1500 sl is included. It should be mentioned that this stack is triggered by a fuel cell start-up battery with a 2 \(\times\) 12 V output voltage and 120 Ah current capacity. This stack cabinet also has a 1500 W power-rated electronics load combined with it. A user-friendly interface is embedded into the PEMFC stack. All these DG elements are connected to the load side with a 2400 W-powered hybrid inverter. As a complementary power source, a battery bank contains six batteries, three connected in parallel and two in series, which are equal to 600 Ah current capacity, 24 V output voltage, and 14.4 kWh energy capacity. To operate the system to meet the desired  
Figure 1: Overall system diagram. requirements, a central energy management unit is employed. This energy management system collects data for visualizing and controlling the power flow from the DG to the load side. This energy management system can be controlled by a user interface connected to the system. The monitoring and control part of the DG system consists of two main parts: energy production and energy storage. The energy production units comprise a wind turbine, PV modules, and PEMFC system. The storage part consists of a battery bank, hydrogen canister, and electrolyzer. A Proton Exchange Membrane (PEM)-type hydrogen fuel cell is used as a backup energy generation system in this hybrid DG structure. Since the polymer material is used as the electrolyte in the hydrogen fuel cell, these fuel cells are known as PEM cells. The electrodes used are carbon-structured. The most important feature of the PEMFC is that it has a membrane with proton conduction. The polymer membrane used is thin, small, and light. The most commonly used membrane material is Nafion(r), manufactured by DuPont (Wilmington, DE, USA). This membrane must be made of a material with high thermal, mechanical, and chemical resistance that is impermeable to water, fuel, oxygen, and other gases in the air. The wind turbine and PV modules on the rooftop of Marmara University, Faculty of Technology, are shown in Figure 2. The laboratory room with the wind turbine, PV modules, stack of hydrogen fuel cells, battery bank, electrolyzer, hydrogen canister (metal hydride tube), and other components is shown in Figure 3.  
Figure 3: The DG system components. Figure 2: Wind turbine and PV modules on the rooftop of the faculty building. The wind turbine specifications are given in Table 1.  
The Weibull probability density function is generally used to calculate the energy generated from wind turbines, depending on the momentarily variable wind. \[f(v)=\frac{k}{c}\Big{(}\frac{v}{c}\Big{)}^{k-1}\exp\biggl{[}-\Big{(}\frac{v}{c} \Big{)}^{k}\biggr{]} \tag{1}\]  
where \(k\) is the shape parameter, and \(c\) is the scale parameter. In the case where much detail is known about the wind regime in a region, the \(k\) shape parameter can be set to 2. In this case, the Weibull probability density function is known as the Rayleigh probability density function [21].