Three stages control strategy for hybrid electrical energy systems

This paper describes a three stages control strategy for electrical energy transfers in multisource renewable energy systems. The aim of the control design is to optimize the energy transfers, according to the sources power variations and the load characteristics. The proposed controller determines the operating mode of the multisource renewable energy system, calculates the power ratio provided by each source and drives the dc/dc converters with local current and voltage loops. Another contribution of this work consists in using an estimation of the duty cycle value of the dc/dc power converters as decision criteria to switch the power sources and drive the power ratios. The proposed method doesn't need extra sensors to measure the available power sources for switching. The performance of the controller is compared with classical method based on direct measurements of the available powers (solar radiations, wind turbine shaft speed/torque).