Frequency regulation of hybrid renewable energy system for large band wind speed variation

A proportional-plus-integral (PI) controlled based small-signal analysis of isolated autonomous hybrid system with different energy storage combinations is presented in this paper. The hybrid systems supplying power to isolated loads comprise of different renewable energy resources such as wind, photovoltaic (PV), fuel cell (FC) and diesel engine generator (DEG) along with the energy storage devices such as flywheel energy storage system (FESS), battery energy storage system (BESS). Large band wind speed based on Van der Hoven´s model is also presented in this paper in order to analyze the frequency deviation due to mismatch between power generation and load demand. Further ultracapacitor (UC) as an energy storing element and PI controllers are incorporated in the hybrid system in order to improve the frequency deviation. A comparative assessment for different hybrid systems in the presence of different storage system combinations and PI controller is carried out which reflects the improvements of the deviation in frequency profile in the presence of the ultracapacitors (UC) as compared to other storage elements.