Abstract:

The power grid for supplying and the standby transformer power grid of UHV transmission units may be connected to 2 regional power grids, which brings problem to switching and operating between station service power supply and standby power supply. Through research and analysis, it is recommended to place a generator circuit breaker to avoid problems when station service power supply is shut off and switched to another grid. During the abnormal operation of high/low voltage systems of factory service power supply, nonsynchronous parallel switch can be added in the closing circuits to help contact to interlock. The closing circuit with decentralized control system, logic blocking and criterion from the same grid, can not only meet the parallel switching requirements on the factory lowvoltage system when the operating mode changes, but also prevent the nonsynchronous parallel accident.

Key words:

thermal power unit, differential frequency power supply, different grids switching, different grids operation, nonsynchronous parallel, preventive measures