Fuzzy control of an electrical energy generation system based on renewable sources

The control of low power systems, which include renewable energy sources, a local network, an electrochemical storage subsystem and a grid connection, is inherently hierarchical. The lower level consists on the control systems of wind sources (power limitation at rated value in full load regime and energy optimization in partial load regime) and photovoltaic (energy conversion optimization). The control problem at the higher level is treated in this paper and aims at generating the control solution for the energetic transfer between the system components, given that the powers of the renewable energy sources and the power in the local network are random variables. For the higher level, the paper proposes a mixed performance criterion, which includes an energy sub-criterion concerning the costs of electricity supplied to local consumers, and a sub-criterion related to the lifetime of the battery. It was defined an algorithm to control the energy transfer in the system, implemented by using fuzzy techniques and a deficit/surplus prediction of energy in the system.