Research and Application of FCB Control Strategy for Single-shaft Gas-steam Combined Cycle Unit
In order to strengthen local power supply construction and improve the response to large-scale power outages caused by unexpected factors,Guangdong Power Grid has put forward clear requirements for the isolated operation capacity and"black start"function of combined cycle units.It relies on the second phase infrastructure debugging project of a certain gas turbine power plant to carry out two sets of AE94.3 A gas steam combined cycle"one driven one"single shaft unit fast cut back(FCB)tests.The experiment simulated a fault in the external trans-mission circuit of the power grid,and the unit achieved the goal of"isolated grid operation"by quickly switching the circuit breaker of the power grid.The steam turbine tripped,the gas turbine quickly cut off the load,and the output power was reduced to with plant power.During the experiment,all parameters changed smoothly,and the main and auxiliary equipment were safely shut down.The experiment achieved good results.Through targeted optimization and improvement of control strategies for steam turbine bypass system,boiler overheat/reheat cooling wa-ter system,steam drum liquid level system,condensate and vacuum system,shaft seal system,etc.,the unit has complete and reliable FCB function,significantly enhancing the reliability of power supply on the power side.Relevant experience can be used as a reference for similar u-nits in the future.
gas-steam combined cycle unitFCBisolated network operationthermal control strategy