ABSTRACT
This work focuses on the operation control of stand-alone hybrid systems and presents a recent development of system operation. The basic objectives of the developed concept are to achieve consistent technical and economical operating conditions for the system components, especially for the battery and the back-up unit. This concept is flexible enough to account for the actual status of the components (e.g. -battery state of charge (SOC), stratification level in the battery, -renewable energy availability, -diesel loading ratio, etc.) and decide hour-to-hour the most efficient energy dispatch strategy. To consider the continuous changes of the components status, (e.g. battery ageing) the dispatch decision module is designed on the bases of event driven mechanisms, in which the system transfers from one state (mode) to another prescribed state based on the actual components status. Also, the constraints imposed on the components operation have been taken into account. Simulation results illustrate that longer lifetime of the battery is rather achieved via the developed operation control concept than via traditionally used ones. Continuous checking of the battery state of health and suitable sizing of the back-up unit with efficient use of its characteristics keep the battery from quick ageing and reduce the total system replacement, operation and maintenance costs.
