Mitigating power fluctuations for energy storage in wind energy conversion system using supercapacitors

Abstract

The world is rapidly shifting to green power resources due to inevitable growing energy needs and increasing environmental concerns. However, the irregular production capacity of renewable energy resources requires additional components in the system for conditioning power quality and to make them a sustainable solution. It imperatively needs an energy storage system, which is crucial for the wind energy conversion system (WECS) to maintain a smooth power supply to loads. However, voltage fluctuations from the wind turbine generator, which are caused by the turbulent nature of wind speed, pose disruptions to the DC charge controller of a battery, and affects battery life. To deal with power fluctuations of the wind turbine generator, this study proposes a WECS that integrates a supercapacitor before the stages of the DC charge controller and the energy storage device. Given that batteries have transient charging and discharging characteristics, a test bench is developed to analyze their patterns during the charging/discharging cycles. The DC charge controller in the proposed WECS is designed to operate in the constant current mode as well as constant voltage mode depending on the state of charge of the battery. The simulations and experiments associated with the performance of WECS with a hybrid energy storage system and conventional system are carried out and presented to substantiate the assertion. To validate the proposed idea, the performance of the WECS and improvement in battery life are examined through the charging pattern of battery before and after the integration of a supercapacitor. The behavior of wind turbine generator variables due to the integration of supercapacitor in WECS is analyzed and discussed in detail. A prototype of WECS combined with an arrangement of a supercapacitor (500 F, 2.7 Vdc) module is built and tested. The simulation and experimental results indicating the impact of the integration of supercapacitor in WECS are presented.