3-PHASE MULTIFUNCTIONAL BATTERY ENERGY-STORAGE SYSTEM

A three-phase multifunctional battery energy storage system (BESS) is designed and implemented. When the utility power is in normal conditio n, the proposed BESS can be arranged to shave the peak load or charge the battery bank. In either case, since the load unbalanced, harmonic and reactive powers can be compensated through the proposed active pow er filter control, the power factor is maintained at nearly unity and the line currents drawn from the utility are balanced and sinusoidal w ith very low distortion. As the utility power failure occurs, the prop osed BESS can immediately supply uninterruptible power to the loads. I n this case, an instantaneous control technique is developed to yield good three-phase voltage waveforms. The determination of the reactive components, the dynamic modelling, and the design of controllers for t he proposed BESS are introduced. A 5 kVA prototype system is implement ed and some experimental results are provided to demonstrate the funct ions and performance of the proposed BESS. Finally, the strategies for scaling up the power capacity of the proposed BESS are discussed.