D11 Hydraulic Oil pump Control


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We are a 2x1 combined cycled power plant. Currently there is no automation on our steam turbine hydraulic oil pumps other than a swap over on low pressure. Otherwise, the pumps run 24/7.

I am planning to automate this so that they will shutdown when the steam turbine is offline.

How do other sites control these pumps?
Sorry, I should have mentioned that we are a peaking plant, starting and stopping once or twice everyday.
Historically, steam turbines were started and run for months, years even. It's really only in the last couple of decades that steam turbines have been cycled in load-following and combined cycle applications.

GE is sometimes slow to change. For years, the turbine control system they provided didn't deal with auxiliaries like motor control centers; that was all handled by the plant control system. The turbine control system was primarily only for controlling the steam flow and protecting and monitoring the steam turbine and little else. A lot of the steam turbine auxiliaries were manually controlled, again, because they were usually put into service and left in service for long periods of time.

It's really only been in the last twenty years or so, basically since GE started using Mark Vs to control steam turbines, that they began to incorporate more of the steam turbine auxiliary control into the steam turbine control system.

GE steam turbine control engineers have also been largely of the opinion that it's not a bad idea to keep the hydraulic oil circulating when the turbine is not running for "brief" periods of time. It's all relative.

Only you know how your plant is operated. Not all plants are operated the same, especially in these "de-regulated" and "independent power producer" days. Do you shut down once or twice a day? Once per week? How long do the shutdowns last?

Reliability and protection are the biggest concerns; just be sure to incorporate those into whatever scheme you devise.
We have been starting daily during the week and are typically down on the weekends. There are periods when we will go weeks without a startup. I have ordered a circulation heater to install into the conditioning pump circuit to keep the oil warm and moisture free. The issue we have is that the hydraulic pumps are expensive to run (estimated $60-70 per day). I would like to implement a control scheme that will start the ST hydraulic pumps when the GTs first fire, and keep them running for 24 hours after the units are shutdown.
When you own the machine, and there is no contractual obligation for any warranty or guarantee from a contractual services provider, you are free to operate the machine, and to automate functions, as you see fit for your site and operating conditions.

You seem to have covered most of the bases. The only thing which I would wonder about is the winter ambient conditions and what might happen to any oil in the piping between the hydraulic power unit and the actuators on the control valves. Is the piping lagged and possibly heat-traced?

Your operating procedures will likely need to start the pump some period of time before an anticipated start to circulate oil to warm the pipes and return/drain lines, not to mention the oil in the servo-valves.