ARES - A REFINED SIMULATION PROGRAM FOR THE SIZING AND OPTIMIZATION OF AUTONOMOUS HYBRID ENERGY-SYSTEMS

This article outlines several enhancements made to autonomous renewabl e energy systems (ARES)-I, the Cardiff School of Engineering's hybrid photovoltaic and wind energy simulation program. The resulting program , ARES-II, unlike the majority of other hybrid simulation programs, pr edicts the battery state of voltage (SoV) rather than its state of cha rge (SoC). Loss of load (Lot) occurs when the battery voltage drops be low the low voltage cut off limit. Given load and weather profiles, AR ES-II is able to predict the occurrence of loss of load thus giving a direct measure of the system autonomy. The enhanced model also predict s the effect of different battery temperatures on the Lot. Experimenta l work has shown a significant change in storage battery resistance an d capacity with temperature. Incorporating battery temperature effects into the battery algorithm is a novel advancement in hybrid system vo ltage simulation. Further refinements have also been made to the volta ge controller algorithms. Accurate modelling of the non-linear action of the low voltage controller is of paramount importance when predicti ng loss of load probability for hybrid systems. Combining all the abov e features and incorporating them into ARES-II produces a simple, accu rate and reliable method for hybrid system design and Lot prediction a s a function of the combined variability in the weather and load. (C) 1997 Elsevier Science Ltd.