Parallel operation of GTG with GRID


Thread Starter

prashant desai

I have 03 GTG (SIEMENS SGT300 with Alstom TEMPEST model Generators) each 5.5 MW with 6.6KV, 50 Hz direct connected to Load bus of 6.6KV. There is separate Turbine control & Gen control panels for each of GTG--these TWO panels are hardwired for necessary talk between them to fulfill functionality of Normal operation of GTG including parallel operations. Now i am going for GRID connectivity with 66/6.6KV grid transformers. Presently all GTG are under 4 % droop -both AVR & governers. My Query is When GTG will be put parallel with GRID, what mode of operation will be required? I know that my GTG will require Droop live and i have TWO options:

1) Put GTG in fixed MW ouput mode and rest of load will go onto GRID automatically ...Or.....

2) Put GRID Import MW limit (in new controller) and rest of MW (from plant load) will go onto GRID ...

i prefer option 2 for monitoring Import MW within Contract Demand with GRID supply Authorities, but in this case variations in GRID volt & freq will have to be followed by GTG controls--How MW /MVAR on individual GTG will get controlled? and also Pf of individual GTG will get maintained around 0.8/0.85? How my New controller can maintain load Bus volt & freq by sending correction pulses to all running GTGs AVR & governor both? Will my Gen to be put under Pf/VAR mode? then on Islanding, will i have to change my mode of governor/AVRs for stable island operations?