Power-limited energy storage power supply

Secondary energy storage in a power system is any installation or method, usually subject to independent control, with the help of which it is possible to store energy, generated in the power system, keep it stored and use it in the power system when necessary.

As a consequence, the electrical grid sees much higher power variability than in the past, challenging its frequency and voltage regulation. Energy storage systems will be fundamental for ensuring the energy supply and the voltage power quality to customers.

There are three possibilities for the use of storage in the power system: compulsory regime; optimal regime; and reserve regime. A compulsory regime arises when the planned load curve coincides with the rated load curve; there is a necessity for the energy storage unit to ensure power balance in the system.

An energy storage unit can be connected to the transmission, subtransmission or distribution system in a manner similar to customer-owned conventional or renewable generation facilities such as gas or wind turbines. These dispersed sources are able to change the character of a typical electricity power system completely.

As a consequence, to guarantee a safe and stable energy supply, faster and larger energy availability in the system is needed. This survey paper aims at providing an overview of the role of energy storage systems (ESS) to ensure the energy supply in future energy grids.

In an electricity power system based on thermal, nuclear, hydro and renewable generation, storage will find a wide field of application and may perform various duties, which must be taken into consideration in order to gain the largest possible advantage in the supply side optimisation.