A Lumped Model of All-Vanadium Redox Flow Batteries

One of the operational issues associated with using renewable energy to generate 20% of the nation’s total electrical energy consumption is that both the ramp rate and the magnitude of the electrical load balancing requirement are expected to increase significantly. In meeting increased ramp and capacity requirements, the regulating generators may not be able to operate reasonably close to their preferred operating points, resulting in lower efficiencies. Hydro power plants, batteries, flywheels, and demand-side management are flexible options that could provide the needed fast-responsive ancillary services. Compared with other types of batteries, the redox flow battery (RFB) has advantages such as rapid response, flexible sizing and upgrade, and long lifetimes at any given state-of-charge. Although RFB systems have been used widely in distributed renewable power plants, their performance for fast regulating services has not yet been investigated.