Mark VIe control system

N

Thread Starter

N.V.Q

Dear CSA

Could you please tell me function mark VIe normally control for steam turbine & generator system?

It quite hard, because it depend on scope of each project requirement, but I am asking the normally when Mark VIe control STG, what function/mode of STG system it is going to control?

Your explanation could be highly appreciate.

thank you very much.
 
N.V.Q,

For any piece of rotating equipment driving an AC generator speed control is most important. For steam turbines, preventing overspeed is very critical.

As you so correctly noted, project requirements do dictate other modes of control. There is Acceleration Control, Load Control, Inlet Pressure Control, Extraction Control (Single or Double; Auto or Manual). For large steam turbines there is often also a Power-Load Unbalance unit--again for protecting against overspeed.

Those are the basic modes of control, again, depending on project requirements there can be others. Another respondent, JFB, has decades of experience with steam turbine controls and could list even more modes I'm sure I didn't even realize existed.

As for "generator control" in most GE steam turbine control systems, generator control is usually accomplished with a separate excitation control system. The Mark VIe usually does very little with auxiliary control in most steam turbine applications, focused primarily mostly on steam turbine control and protection. Quite frequently, even hydraulic power units and lube oil pumps are controlled manually or by the plant control system--not the GE turbine control system.

I hope this is helpful.
 
> Those are the basic modes of control, again, depending on project requirements there can be others. Another respondent,
> JFB, has decades of experience with steam turbine controls and could list even more modes I'm sure I didn't even realize existed.

Thanks for the recondition. You Sir are the one I would like to meet!

As for not replying to the OP original question is because I never made the transition to digital. So I have knowledge of what MKVIe is capable of and how it is done.

I think one needs to knew the design of those preceding control schemes to separate what is needed for control and what is now being done just because the digital has the capability to do so. Listening to of the new field controls guy, I sometime worry if those basics are still being preached (or applied).

If you are interested in the evolution of turbine control, I did a slide show once to educate management of how their existing system work in preparation for a digital conversion. while the slides do need farther explanation for the full benefit, you will see the same important requirements that CSA already stated.

http://www.slideshare.net/JosephFByrdJr/turbine-control-basics

Hope this helps
 
Dear CSA,

Thank for your reply, your clarify about the mode of control the turbine and protection.

In our project, the hydraulic unit and lube oi system is controlled by Mark VIe.

I think, this is no problem to control turbine auxiliary equipment with Mark VIe even pump, valve ON/OFF control and regulation control.
 
N.V.Q,

One of the main criteria for the design of the Mark VIe was to expand it to use as more than just a turbine control system--to be a DCS and balance of plant control system. If only GE would use something else for their HMI software (besides CIMPLICITY/PROFICY) they might actually sell more Mark VIes as DCS and BOP (Balance-of-Plant) control systems.

Speedtronic control systems--the forerunner of present-day Mark VIe control systems--were used for "one button" starts of heavy duty gas turbines, which means they controlled a lot of auxiliaries (motors driving pumps and fans; solenoids operating valves and controlling flows; and general plant monitoring and alarming (LOTS of alarms!))--all in addition to controlling fuel and spark and speed and load and starting means and cooldown schemes.

Mark VIe (Speedtronic, as it will always be to me) control systems are very capable control systems in their own right. The documentation provided with them is as good as GE has ever provided--but it still could be LOTS better. Remember, though, that Mark VIe is really just hardware and a programming configuration application (ToolboxST). The way it's used and applied to control turbines and auxiliaries and boilers and water treatment systems is the purview of the "packager"--the 'control system integrator'--and while that may be GE in some cases, it's a different division of GE which has it's own profit and loss goals and responsibilities.

And therein lies the problem GE doesn't even recognize about Speedtronic control systems--the divisions that program and package the Speedtronic control system hardware using the programming and configuration software developed by another division of GE are responsible for documenting--and training--people about how the equipment is being controlled and protected using the Speedtronic control system. But, that's not what the divisions of GE that's doing the packaging believe--they believe that the documentation provided by the division of GE that produces the hardware and programming and configuration software is "GE" ("Good Enough"). And it's not. In some cases, the hardware and software and programming and configuration software are built specifically to accommodate turbine control philosophies. But it's important--for GE!!!--to recognize that the responsibility for documentation of how the Speedtronic controls turbines is the responsibility of the packager of the control system since the packager decides how the turbine operates and what the control philosophies and schemes are that are implemented in the control system they provide with the turbine. That requires much more than the documentation that comes with the Mark VIe hardware and ToolboxST--it's how the hardware and ToolboxST are used to control the protect the turbine, and what's supposed to happen and when.

That's the really important part of the documentation that's missing--and GE needs to recognize this. For their Customers, as well as their engineering teams, and their field service personnel.

Anyway, I digress. But, you are still right--the Mark VIe is very capable, and pretty robust. As with all electronics, though, there seems to be occasional and intermittent issues with the quality control of their overseas (outside of North America) manufacturers.
 
JFB,

I would be honored to carry your tool bag, sir, just to be able to learn at the foot of one of the true, original steam turbine Masters.

I'm glad you didn't say "new field engineers" because they aren't 'engineers' anymore; they're just human relays to the PAC and they aren't even educated how to do that well. But, when management can bend statistics to say that the PAC is cost-effective (and we all know statistics can be--and quite often are--used incorrectly to personal advantage instead of corporate advantage or Customer advantage) that this is what everyone is going to be stuck with.

And, no; the basic philosophies and practices are not being taught or "enforced" (though that's a strong word) these days. Sure, some of the GE A-courses, as they used to be known, still have some of the basics, but it's slowly being pulled out--because many of the instructors don't understand or know what it means or how it can be useful or how to teach it. And a lot of things are being done digitally because someone thinks they should be done but they really don't understand how they should be done. (For example, GE digital steam turbine control systems are awash in Process Alarms because the programmers use a lot of T/Cs to measure metal temperatures in piping and control valves/steam chests/bowls in comparators without deadband or hysteresis--which results in a boatload of dithering alarms. And, they fail to fix this, because, in their simulators simulated T/C signals are always rock solid and they don't have any field experience to the contrary.)

I, too, also find it difficult to find ways of explaining some things when people aren't really interested in history and background--they just want to know how to fix it right NOW. And, that's understandable--but, teaching a man to fish is much more valuable than giving him a fish when he's hungry, right? While fixing it right now is important, knowing how to anticipate and respond before the problem gets critical, and knowing how to deal with nuances by understanding principles and philosophies will serve them much better in the long run, not just on this problem on this machine but on other problems and machines going forward in their careers. But, alas--when fish are so plentiful and easy to obtain, people forget that you reap what you sow--and if you don't sow anything you won't reap anything eventually. How's that for philosophy?

Anyway, thanks for the input--and the link! Hope all is well with you! Hopefully we will meet some day, Sir.
 
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