ABSTRACT
The aim of the paper is to analyse and improve existing management strategies applied to renewable energy based stand alone hybrid systems including battery storage and conventional back-up supply and to evaluate the gain brought by modified strategies. A system including controllable energy supply and not only based on variable energy sources allows a greater number of freedom degrees in the energy dispatching point of view. This increased flexibility is of particular interest in order to better control the battery state of charge evolution with time. Focusing on a rational use of both renewable and conventional energy and since the grid back-up is the only power source to be controlled, different strategies of operation can be described taking into account the following parameters: starting time, power of operation and duration of operation from starting time. Examples of strategies of grid back-up used for actual hybrid systems are given and their advantages and drawbacks are highlighted. We define an improved management strategy of the energy stored in the battery under the particular criteria of maximising the use of available renewable energies and minimising energy taken from the grid.
