Design and Analysis of a Battery and Super Capacitor Based Hybrid Energy Storage System

This paper proposes an energy storage system (ESS), to satisfy the load demand, is very much essential. BESS is mostly preferred due to its high energy density. It responds slowly to sudden changes during transient conditions. Hence an ESS having high power density like a Super Capacitor has to be accompanied with Battery to form a HESS. A 48 V DC link is connected via PV Array and the ESS. In this work when the output power from the solar increases the HESS takes the excess power to maintain constant power supply to the load and supplies back the energy to the load when the PV is inefficient in supplying the load demand. A combined control strategy is proposed which effectively generates the switching pulses to the bidirectional converter. The total current to the HESS is generated from the voltage control loop. The current control loops are designed and the stability is analyzed. Bode plots are used to test the stability of HESS. The results obtained are promising and the controller does good dc link voltage restoration and effective power sharing between SC and battery. It is found that HESS is good in supplying average power during long durations and handling transient conditions for short durations using the proposed controller.

Keywords: Battery, Renewable energy, Energy Storage System, Hybrid Energy Storage System, Super Capacitor.