I want to be familiarized with the operation of SFC in GT (both barring mode and starting mode). Kindly help in this regards.
Thanks in advance.
control.com has an excellent 'Search' feature at the far right of the Menu bar at the top of every control.com page.
Use the following search term:
+"static frequency converter"
just as typed above. You will find several good threads with lots of information guaranteed to answer at least some of your questions (Note: We don't like 'doubts' here!) and provide additional information you may not have thought of.
However, should you require additional information you can always write back with specific questions about what you have read or something that wasn't covered or wasn't clear.
One of the great things (there are several!) about the GE heavy-duty gas turbine and -Speedtronic control community here at control.com is that a lot of questions have already been asked and answered--some (like those about droop speed control) have been asked and answered MANY times over. So, when you have a question (not a doubt) you should always Search the site for previous threads as you begin your quest for knowledge and understanding. A great many related topics have been covers over a decade or more.
Lastly, SFCs are also called LCIs (Load Commutated Inverters) and "static starters"--two more terms you can use in your search for information. Just like when searching the World Wide Web, some concepts or pieces of equipment can be called by or described with more than one name or term, and as you search you should always be aware of this and use many different combinations of words and terms whenever searching the Web, and control.com.
So, do some research and if you still have questions (not doubts) ask them here and we will do our best to answer them. Consider control.com your first place to search and then ask specific questions if you still need more explanation or have additional questions.
Normally in GT, the gas coming out from the turbine will have less capability to run the rotor of synchronous machine..so we are using sfc which will make the machine to run as the motor while starting..so the rotor will start to rotate very fast with the help of motoring action from sfc and gas from turbine....once required speed is attained...we will cut off the sfc supply.
In starting mode:
Here the incoming ac supply will get converted into dc by 6 pulse rectifier and we will have dc choke in dc bus to control the current output.so we can call it as current controlled device.Then dc will get converted to ac by inverter and finally fed to the stator.
In breaking mode:
The thyristor which is located in the machine side inverter can get switched off only because of the back emf induced in stator windings. But we know that the back emf is very less in starting condition. so in order to switch it off, we will go for breaking mode.