Dynamic modeling and simulation of renewable energy based hybrid power systems

This paper describes dynamic modeling and simulation results of a renewable energy based hybrid power system. In order to meet sustained load demands during varying natural conditions, different renewable energy sources need to be integrated with each other. The paper focuses on the combination of solar cell (SC), wind turbine (WT), fuel cell (FC) and ultra-capacitor (UC) systems for power generation. As the wind turbine output power varies with the wind speed and the solar cell output power varies with both the ambient temperature and radiation, a FC system with an UC bank can be integrated to ensure that the system performs under all conditions. Excess wind and solar energies when available are converted to hydrogen using an electrolyzer for later use in the fuel cell. Dynamic modeling of various components of this isolated system is presented. Transient responses of the system to step changes in the load, ambient temperature, radiation, and wind speed in a number of possible situations are studied. The results show that the proposed hybrid power system can tolerate the rapid changes in natural conditions and suppress the effects of these fluctuations on the voltage within the acceptable range.