RENEWABLE ENERGY STORAGE AND INTEGRATION – THE ROADMAP AND TECHNICAL CHALLENGES

Prof. Ankur Bhattacharjee
9.12.2016

Govt. of India has announced a target of 175 GW Renewable power project by the year 2022 under “Jawaharlal Nehru National Solar Mission” (JNNSM). Looking at the projected plan, it is necessary to think about the future impact of large scale penetration of Renewable Energy (RE) sources into the existing grid. The Grid end problems (Voltage and frequency fluctuation) are classified in to two major categories;
1. Low voltage distribution grid (Weak Grid condition) problem,
2. National grid problem.
Optimized interface of energy storage with the RE sources is therefore a strong point of interest for the new age research and development. Different energy storage technologies have been analysed here for RE application specific choice of energy storage. Depending upon the power management and energy management criteria, the battery storage technology is considered suitable. There are existing battery technologies like Lead acid, Li-ion, NaS which are established as off grid back up power supply. But the new generation Redox Flow batteries claim to be the most suitable storage solution for large scale grid tied Renewable power system. Among the flow batteries, Vanadium Redox Flow Battery (VRFB) appears to be most acceptable due to its independent scalability of Power and energy capacity, very long lifecycle and deep discharge capacity. To implement the optimized battery storage system with RE sources, an efficient battery management system (BMS) is of high demand. There are significant battery internal parameters like; state of charge (SOC), battery temperature, internal impedance, thermal aging, and electrolyte flow rate (for VRFB) need to be taken care of to design an efficient BMS to enhance storage lifetime and overall plant efficiency.