I. Introduction
Technological developments make the use of alternative energy resources in global energy production more necessary. The reason is that the harmful effects of fossil fuels increase the interest in alternative energy sources [1]-[3]. Within alternative energy sources, fuel cell systems become more attractive year by year due to high-efficiency electricity generation and low / zero gas emissions [4]. In recent years, with increasing capacities, fuel cells have been implemented in the integration of the electricity grids. Similar to photovoltaic systems, the integration of grid and fuel cell systems is defined as the grid-connected fuel cell system [5], [6].