Decreasing Owning Costs of MV/LV Substations Backup Batteries

From the utilities point of view, backup batteries are very important to secure substations of the electrical network. The economical criterion for those batteries are mainly the upfront capital costs and the operational costs including maintenance. Facing the battery\´s owning costs in the 2300 substations under operation in France, Electricite de France Research and Development has developed an innovative system called "Stationary Multibat". From an economical aspect, we have focused our work on the development of a battery management system adapted for low-cost batteries and the use of GSM supervision for reducing maintenance interventions and costs. Then, during the year 2004, EDF R&D has patented the system and developed a laboratory prototype of a 20 kWh backup system under 48 V which includes the following aspects: use of a low-cost lead-acid battery, use of a battery array with parallel strings managed independently to increase reliability, development of a battery manager monitoring capacity periodically and controlling the charge and floating state to be adapted for the selected low-cost batteries, remote control by GSM for maintenance service