Role of the battery storage in the operation of the power system

The application of the batteries only for power system scale stationary energy storage is not the best investment. The power electronics combined smartly controllable storage units has more benefits in the power system operation. In the last years spread over the small household kW scale batteries, the Plug-in Hybrid Electric Vehicles (PHEV) and the medium size MW scale battery storage facilities. The operation of these tools affect differently the power systems. The main role of household devices is to store the daytime generated PV energy and push back it in the early night hours. It is a rough change in the customers daily demand profile and affects the global load curve too. The PHEV-s have mainly security storage role. In case of smaller system disturbance the thousands of Electric Vehicles (EV) can feed back to the (low voltage) power system some energy that can ease the power system level power lack. The medium size battery banks can serve as primary source for the load-frequency control (FCR), but also can form reserve for the secondary control (FRR) in the large power systems but in the smaller microgrids as well.