Renewable energy is best utilized when partnered with energy storage to balance the variable supply with daily and seasonal grid demands. At the distribution level, in addition to meeting power demands, there is a need to maintain system voltage and reactive power / VAR control. Rotating machinery is most effective for VAR control at the substation level. This paper presents a patented MW-scale system that provides power from a hydrogen-oxygen-fueled combined cycle power plant, where the hydrogen and oxygen are generated from electrolysis using renewable wind or solar power. The steam generated from combustion is the working fluid for the power plant, in a closed loop system. Also presented is a discussion on a patented strategy for safe combustion and handling of hydrogen and oxygen, as well as how to use this combustion strategy for flame and post flame temperature control. Finally, a preliminary benefits analysis illustrates the various energy storage and distributed generation benefits that are possible with this system. Depending on the storage approach, energy storage — charge and discharge durations — of 4 to greater than 24 hours are possible, much longer than most battery energy storage systems. Benefits include not only peak shaving and VAR control, but also grid balancing services to avoid the “spilling” of excess renewable power when supply exceeds demand and fast ramping in the evening hours.
Reactive Power Injection from Battery Energy Storage During Voltage Dips at a Thermal Power Plant
