I am fresh I&C engineer in combined cycle power plant which is in construction phase & soon it moves to commissioning phase. So I need some assistant which is helpful is starting commissioning that what documents required from contractor, from where I start.
Please help me out about commissioning phase and share your commissioning experience. I hope this information will be useful for all fresh engineers.
Comissioning Activities - I have exclusively been part of commissioning group for co-generation power plants , both gas and steam. The commissioning activities vary depending on the type of plant , the nature of the client , the nature of the consultant and most importantly the operating flexibility of the plant. COgeneration plants are small but commissioning them is a little more time consuming as you have to commission the plant together with a bunch of other operating plants in the same system. this takes extensive cooperation from the plant operating personnel also. well commissioning starts as soon as the first trial run of the plant starts. it is when the erection groups hands over the plant to the commissioning group. The extent of commissioning and the ease of commissioning depends on a lot on how well the plant was erected by the erection group. The core commissioning group is small. there will be a electrical engineer, mechanical engineer, a instrumentation engineer and a group head, and yes there will be a few technicians. most of the people are cross trained each can take the responsibility of the other with ease. This is one of the major attraction of being in commissioning , you get to learn electrical , instrumentation , mechanical and even a little bit of civil engineering.
First thing for a commissioning group is to get the feel of the plant and the surrounding system. The group head allocates the tasks to the engineers after taking into account the nature of the job at hand. There are a few must knows before commissioning , like the plant operating philosophy , nearby systems , extent of completion of the different systems and subsystems in the plant.
After the task is generally divided into the following category
a. Electrical Engineer
- HT panel Inspection, testing and commissioning
- LT panel inspection . testing and commissioning
Both the above takes quite a bit of time depending on how well the erection had been made, predominately this is done
- Testing of power cables (if not charged yet)
- Testing of Control system interlocks in the switchgear
- HT Breaker/LTbreaker / MCC module healthiness checking
- Testing of proper feed back in the electrical SCADA system (open/close, power, current, voltage values etc ...)
- Panel Relay setting, inspection and testing
- Testing of CT's PT's and HT gear transducers
- generator and auxiliaries inspection, testing
- Turbine axillary drives testing
- Boiler/HRSG axillary drives testing
- generator control panel testing and commissioning
- ECP or electrical control panel for plant HT and LT switchgear testing and commissioning
- Generator relay panel testing, setting revision and commissioning
- Plant DC system testing and commissioning
- Plant UPS system testing and commissioning
- Generator AVR testing, tuning and commissioning
b. Instrumentation Engineer
- Turbine control system testing, tweaking and commissioning
- Plant DCS system (Boiler and BOP) testing, tweaking and commissioning
- Plant SCADA system (electrical switchgear control) testing and commissioning
All the above work involves more or less the same type of work
- Testing (occasional calibration and replacement) of Plant field instrumentation
- Testing and commissioning of plant control valves (loop checking and ensuring proper feedback)
- Testing commissioning of plant solenoid valves (proper operation and feedback
- Testing and commissioning of plant MOV (with electrical engineer, this by far in my opinion is the most back breaking work and in the quest of complete automation there are literally 50-100 MOV's in each co generation plant, i don't know MOV's and me do not go well )
- Testing and commissioning of plant servo's (a very subtle art :) )
- Testing and calibration of plant measurement circuits, pressure, temperature, flow, speed, position and vibration probes. They also take a lot of time mainly because they form a major quantity of the plant instrumentation.
- Testing and commissioning of plant analyzers, In boilers, it will be PH, silica, conductivity, phosphate, SOx, NOx, CO, unburnt fuel and oxygen analysers. This work as far as i have seen is exclusively done by the vendors. all you have to do is to verify the operation and sign :).
- Testing and tweaking of graphics, minor modifications in consultation with plant operating personnel.
- testing and tweaking of control constants and minor (to sometimes major) logic modifications in application code to the controllers.
- hanging around a lot of time in marshaling units, RTU's, in the field and in front of the controller, thinking, scratching your head and desperately wising to god that atleast this should work.
- Testing and commissioning of other plant systems, which do not form the part of the typical turbine and DCS control. They include
- Turbine and generator CO2 release system
- Plant and Trubine heat sensors and fire detectors panel
- MCP (manual call points) system and associated auxiliaries
- Plant communication system (another exclusive vendor area)
c. Mechanical Engineer -
- Coordinating any turbine mechanical system commissioning
- Trubine axillary drive testing
- Boiler auxillary drive testing
- Supervise plant piping (though i finished it in three words, it is tough work)
- Memorize the plant layout and the plant PID so that you can be ready for anything the electrical and instrumentation engineer will throw at you (here is a typical example of how a lube oil pressure low in a turbine is resolved ;
Instrumentation engineer - "Interlocks are working fine, my signal is through to the MCC panel, may be it is a electrical problem "
Electrical Engineer - "The mCC panel is energized, i checked my AOP motor healthiness it is absolutely OK it is a mechanical problem, perhaps you should check the relief valve in the suction, or perhaps the pump itself is not performing well "
Mechanical engineer - " The pump has a relief valve in the discharge you dumb shits !!, and it is a new pump for gods sake ")
- Responsible for Boiler / HRSG commissioning activities
- Drum internal / heat exchangers cleaning
- alkali boilout
- Piping hydro testing
- Boiler hydro testing
- coordinating with the instrument engineer regarding boiler/HRSG operation tuning
- safety valve testing and commissioning
- Daerator testing and commissioning
- plant chemical dosing system commissioning
- bribing the boiler inspector at the right time :P even if all systems are 100% OK
- Steam Header charging and targer plate testing
d. commissioning group head
- conflict resolving between members of his own commissioning group on project schedule , division of work , working hours etc ...
- conflict resolving between client , consultant and the vendor who all don't really know what they exactly want
- conflict resolving between plant operating personnel and the commissioning group
- conflict resolving between commissioning group members and their families who complain about long working hours , uneven timing , pathetic moods of their respective sons , husbands and occasional boyfriends :P
- conflict resolving between his own commissioning group and the management higher ups who ask about project delays ,project end date etc ...
well those are the roles and responsibilities , the nature and timing of the commissioning activities differ from site to site , there is always no fixed plan , just a framework which is followed. As most of the plant systems are interconnected, there is always a problem with scheduling. each and every commissioning experience is unique and each as far as i have known have different schedules even though we are almost doing the same work. but the end of commissioning period is marked by
a. Continuous running test to prove the plant reliability
b. Plant disturbance test - a battery of tests carried out to check the survivability of the plant in emergency conditions
c. Performance guarantee test - the final test when the plant is run at full load , readings are taken calculations adjusted to match the specifications :P
d. End of commissioning party - where old enemy's (read company higher ups) , new enemy's (really smug and idiotic operating personnel and consultants) , old friends (your commissioning group of course) and new ones (some brilliant plant operating and maintenance personnel who worked tirelessly with you) drink along with on the same table for the greater good ;)