Over Frquency happened at a windy winter night
 

[LEFT]



[B][I] at [/I][/B][I][U][F**T=&quot]3:00 am[/F**T][/U][/I][B][I] , A sudden frequency fluctuati** happened , that cause the MW output fluctuate with the grid frequency , Unit 7 was at Coordinated Mode ( Boiler Master – Auto , Turbine Set – Auto ) , The load fluctuated accordingly to the frequency from [/I][/B][I][U][F**T=&quot]105 MW[/F**T][/U][/I][B][I] to[/I][/B][I][U][F**T=&quot] 90 MW[/F**T][/U][/I][B][I], and increased to [/I][/B][I][U][F**T=&quot]105 MW[/F**T][/U][/I][B][I].[/I][/B]
[B][I]After a little time, frequency reached [/I][/B][I][U][F**T=&quot]50.1 HZ[/F**T][/U][/I][B][I] – therefore the MW output reached [/I][/B][I][U][F**T=&quot]20 MW[/F**T][/U][/I][B][I],[/I][/B]
[B][I]Also, Boiler Master resp**ds by reducing Air Flow and Fuel Gas Flow for the boiler. The load still decreased until it reached [/I][/B][I][U][F**T=&quot]2 MW[/F**T][/U][/I][B][I], and to [/I][/B][I][U][F**T=&quot](-2 MW)[/F**T][/U][/I][B][I], without coming the signal of Reverse Power.[/I][/B]

[B][I]
At this instant we trip the turbine manually.[/I][/B]
[B][I]We wanted to c**serve the boiler to be in service, but [/I][/B][I][U][F**T=&quot]HP-TBV[/F**T][/U][/I][B][I] opens widely ****** [/I][/B][I][U][F**T=&quot]30 sec[/F**T][/U][/I][B][I]., and sucking all drum level to [/I][/B][I][U][F**T=&quot]+267 mm[/F**T][/U][/I][B][I], resulting [/I][/B][I][U][F**T=&quot]MFT[/F**T][/U][/I][B][I] Protecti** to the boiler.[/I][/B]

[B][I][F**T=&quot]The first out indicati** of [/F**T][/I][/B][I][U][F**T=&quot]MFT[/F**T][/U][B][F**T=&quot] at [/F**T][/B][U][F**T=&quot]BMS[/F**T][/U][B][F**T=&quot] was [/F**T][/B][U][F**T=&quot](Drum level HH).[/F**T][/U][B][F**T=&quot] “[/F**T][/B][/I]

[I][B][F**T=&quot]
There were a lot of discussi** and arguments about what is the cause of this accidents , and what should operators do ?[/F**T][/B][/I]
[I][B][F**T=&quot] [/F**T][/B][/I]
[I][B][F**T=&quot]I attached A chart Table shows the different parameters changed at each same time !! , If any **e has an opini** about what happened , plz tell me !![/F**T][/B][/I]




[/LEFT]

مشكور على الكتاب