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For the species of bird, see Blackstart.
A black start is the process of restoring a power station to operation without relying on external energy sources.
Normally, the electric power used within the plant is provided from the station’s own generators. Often a transmission line will be installed to provide this station service power if all the main generators are shut down. However, during a wide-area outage, this off-site power supply will not be available. In the absence of grid power, a so-called black start needs to be performed to bootstrap the power grid into operation.
To provide a black start, some power stations have small diesel generators which can be used to start larger generators (of several megawatts capacity), which in turn can be used to start the main power station generators. Generating plants using steam turbines require station service power of up to 10% of their capacity for boiler feedwater pumps, boiler forced-draft combustion air blowers, and for fuel preparation. It is uneconomical to provide such a large standby capacity at each station, so black-start power must be provided over the electrical transmission network from other stations. Often hydroelectric power plants are designated as the black-start sources to restore network interconnections. A hydroelectric station needs very little initial power to start (just enough to open the intake gates), and can put a large block of power on line very quickly to allow start-up of fossil-fueled or nuclear stations.
A black start sequence
A typical sequence (based on a real scenario) might be as follows:
A battery starts a small diesel generator installed in a hydroelectric generating station.
The power from the diesel generator is used to bring the hydroelectric generating station into operation.
Key transmission lines between the hydro station and other areas are energized.
The power from the hydro dam is used to start one of the coal-fired base load plants.
The power from the base load plant is used to restart all of the other power plants in the system including the nuclear power plants.
Power is finally re-applied to the general electricity distribution network and sent to the consumers. Often this will happen gradually; starting the entire grid at once may be unfeasible (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 colder climates a similar issue can occur in winter with the use of heating devices).
In a larger grid, black start will often involve starting multiple “islands” of generation (each supplying local load areas) and then synchronising and reconnecting these islands to form a complete grid. The power stations involved have to be able to accept large step changes in load as the grid is reconnected.
Procurement of black start services
In the United Kingdom the grid operator has commercial agreements in place with some generators to provide black start capacity, recognising that black start facilities are often not economic in normal grid operation.
In the North American Independent System Operators the procurement of Black Start varies somewhat. Traditionally Blackstart was provided by integrated utilities and the costs were rolled into a broad tariff for cost recovery from ratepayers. In those areas which are not part of organized electricity markets this is still the usual procurement mechanism. In the deregulated environment this legacy of cost-based provision has persisted, and even recent overhauls of Blackstart procurement practices, such as that by the New England Independent System Operator (ISO-NE), have not necessarily shifted to competitive procurement, despite the fact that deregulated jurisdictions have a bias for market solutions rather than Cost-of-Service (COS) solutions.
In the USA there are currently three methods of procuring Black Start. The most common is Cost of Service, as it is the simplest and is the traditional method. It is currently used by the California Independent System Operator (CAISO), the PJM Interconnection and the New York Independent System Operator (NYISO). Although the exact mechanisms differ somewhat the same approach is used, namely that units are identified for black start and their documented costs are then funded and rolled into a tariff for cost recovery. The second method is a new method used by the Independent System Operator of New England (ISO-NE). The new methodology is a flat rate payment which increases Blackstart remuneration to encourage provision. The monthly compensation paid to a generator is determined quite simply…(and so on) To get More information , you can visit some products about , . The football shoes, sport shoes, soccer shoes, branded shoes products should be show more here!
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