Black start
Hydroelectric plants require power to open intake gates, and to adjust the hydraulic turbines for speed regulation.
Even a wind turbine plant may require a relatively small amount of electric power for such things as adjusting blade pitch and direction.
A hydroelectric station needs very little initial power for starting purposes (just enough to open the intake gates and provide excitation current to the generator field coils) and can put a large block of power on line very quickly to allow start-up of fossil fuel or nuclear stations.
Certain types of combustion turbine can be configured for a black start, providing another option in places without suitable hydroelectric plants.
[2] In 2017, a utility in Southern California successfully demonstrated the use of an energy-storage system based on a lithium-ion battery to provide a black start, firing up a combined-cycle gas turbine from an idle state.
In particular, after a lengthy outage during summer, all buildings will be warm, and if the power were restored at once, the demand from air conditioning units alone would be more than the grid could supply.
In a larger grid, in addition to this "single island" ("bottom-up") approach, different strategies can be involved:[4][5] There are multiple methods of commencing a black start of an island: hydroelectric dams, diesel generators, open cycle gas turbines, grid scale battery stores, compressed air storage, and so on.
In the deregulated environment, this legacy of cost-based provision has persisted, and even recent overhauls of black-start procurement practices, such as that by the ISO New England, have not necessarily shifted to a competitive procurement, even though deregulated jurisdictions have a bias for market solutions rather than cost-of-service (COS) solutions.
The WEMAG battery plant proved that it can restore the power grid after major disruption or blackout.
[20] The output of variable renewable energy (VRE) sources is not predictable, this makes them difficult to use for black start or support in the grid restoration, as the lack of control, inherent in VRE sources, might cause a weak grid emerging from a blackout to collapse yet again.
[23] Wind turbines, mini-hydro, or micro-hydro plants, are often connected to induction generators which are incapable of providing power to re-energize the network.
[24] In 2020, the 69 MW Dersalloch wind farm black-started part of the Scotland grid, using virtual synchronous machines.
