I have gas turbine GE frame 6 with Mark V control system. I want to edit Big Block in Mark V. Let's take example L30COMPV1 - Comparator Block or can someone give an instruction how to create new big block?
One can't "create" new blocks (either Primitive blocks or Big Blocks), but one can create a new rung in a CSP segment that uses either an existing Primitive block or Big Block.
Have you read the chapter entitled "Editing the Control Sequence Program" in the Mark V Application Manual, GEH-6195? I think the sections of the chapter which would be most helpful would be the description of the Editor Window and the various "sub"-windows and their function, and the section 'Rung Editing operations.'
The Control Sequence Editor is not intuitive, but it is the only way to easily (graphically) edit CSP segments. If you want to add a COMP block, which I think is considered a Primitive Block as opposed to a Big Block (but I don't have access to a Control Sequence Editor at this writing), you need to scroll to the area you want to add the block (or rung) and then choose 'Add Next' or 'Add Prev' as appropriate. Then you need to change the rung type to PRIMITIVE (or possibly BBL if you can't find the COMP block in the list of primitives), and choose the PRIMITIVE you want to add. Then supply the necessary parameters.
WHENEVER one wants to edit GE sequencing or application code, it is ALWAYS best to find a similar rung or function block in the existing sequencing or application code and then study it very closely for clues and details. In the case of the Mark V, one needs also to become familiar with the Control Sequence Editor, and the best way to start doing that is to read the applicable section in the Mark V Application Manual, GEH-6195. (If you have a more recent operator, a GE Mark V HMI, you may find information in the newer HMI manual--but I don't have access to that manual at this writing. But, the Control Sequence Editor didn't change, as I recall, when the operator interfaces evolved and changed from <I> to GE Mark V HMI, so the information in GEH-6195 should still be applicable.)
Lastly, if you are just looking around CSP segments using the Control Sequence editor and didn't intentionally make any changes, then just exit the Control Sequence Editor without saving any changes and nothing will be affected. If you have made the changes you want, then save the changes either prior to exiting or as exiting.
You didn't say if you needed to create any new CDB (Control Signal Database) signals. That involves much more than just editing a CSP segment. If you can be more specific about what you are trying to do, we can be more specific about all the steps involved.