|
A black start is the process of restoring an electric power station or a part of an electric grid to operation without relying on the external transmission network.〔Knight, U.G. ''Power Systems in Emergencies - From Contingency Planning to Crisis Management '' John Wiley & Sons 2001 ISBN 978-0-471-49016-6 section 7.5 The 'Black Start' Situation〕 Normally, the electric power used within the plant is provided from the station's own generators. If all of the plant's main generators are shut down, station service power is provided by drawing power from the grid through the plant's transmission line. However, during a wide-area outage, off-site power supply from the grid 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, normally called the ''black start diesel generator'' (BSDG), 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 designated tie lines from another station. 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 the excitation of the generator field coils), and can put a large block of power on line very quickly to allow start-up of fossil-fueled or nuclear stations. Certain types of combustion turbine can be configured for black start, providing another option in places without suitable hydroelectric plants. 〔Philip P. Walsh, Paul Fletcher ''Gas turbine performance'', John Wiley and Sons, 2004 ISBN 0-632-06434-X, page 486〕 ==A black start sequence== One method of black start (based on a real scenario) might be as follows: # A battery starts a small diesel generator installed in a hydroelectric generating station or wind-turbine farm. # The power from the diesel generator is used to bring the generating station into operation. # Key transmission lines between the station and other areas are energized. # The power from the station is used to start one of the nuclear/fossil-fuel-fired base load plants. # The power from the base load plant is used to restart all of the other power plants in the system. 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. Note that there are multiple methods of commencing a black start: hydro-electric dams, diesel generators, open cycle gas turbines, compressed air storage and so on. Different generating networks take different approaches, dependent on factors such as cost, complexity, the availability of local resources (i.e. suitable valleys for dams), the interconnectivity with other generating networks and the response time necessary for the black start process. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Black start」の詳細全文を読む スポンサード リンク
|