Petri nets control design for hybrid electrical energy systems

This paper describes a supervisory control strategy based on Petri nets for electrical energy transfers in multisource renewable energy systems. The aim is to optimize the energy transfers, according to the sources power variations and the load characteristics. For this purpose, the proposed Petri net controller calculates the operating mode of the multisource renewable energy system. This high level controller is combined with a low level one that tunes the power ratio provided by each source according to sources power (climatic conditions) and load variations. An estimation of the duty cycle value of the dc/dc power converters is used to fire the Petri nets transitions, to switch the power sources and also to drive the power ratios.