Dear CSA,

Please explain of the basic governor control of GE mark VIe system.
Basic like what is Governor control, how many mode control?

I have no ideal. For turbine we have SV, CV, RV, IV.

This is electro-hydraulic control to control CV. System to control CV is called governor?

How many modes to control CV? It is on-off control modulation solenoid valve?

Your explain from basic would be highly appreciate.

many thanks

 

N.V.Q,

Please work with GE to get this information. We have discussed this, basically, in the past, but it you want more information you will have to get it from GE.

Most steam turbines are pretty unique machines; until recent years the molds for the turbine cases were literally broken each time a turbine was made--making each one be a unique machine. New materials and manufacturing processes have allowed for more similar types of turbines, but, still--most steam turbine applications are very unique. That's because the boilers where the steam is produced are not very similar, the need for extraction steam varies greatly (there may be one, two, or even three extractions--some controlled, and some not), and the condensers can also be different. So, the control schemes, while using similar loops, can be very unique.

This isn't really a Mark VIe question--because just about any programmable automation controller can be used for steam turbine control these days. What's important is that people understand how the turbine operates and how it's supposed to operate and how it's to be protected. Mark VIe's can be used for steam turbines, gas turbine, hydro turbines, and DCS applications. I'm most familiar with gas turbine applications, and not very familiar with details of steam turbine applications. So, this isn't really a Mark VIe question, it's more of a control scheme and control philosophy question--and the best answers would come from the company that's configuring and programming the Mark VIe for the turbine at your site.

I wish I could do more, but, again--this isn't really a Mark VIe question.

 

> N.V.Q,

> Please work with GE

There are non OEM training companies that do a good job, especially for the basics. you might want to review the courses availaible at HPCnet.com.

 

N.V.Q,

I would also recommend looking at the manuals provided with the turbine (not the Mark VIe manuals--they won't tell you anything about the turbine and its modes of control--only how the Mark VIe works, and that's not what you seem to be asking).

And, as JFB says there are better alternatives to GE turbine and/or turbine control system training. GE make too many assumptions about the basic knowledge of students and do not do a very good job of explaining how a specific turbine at a specific plant operates and how to troubleshoot it using the Speedtronic turbine control system (in this case, the Mark VIe).

 

Thank you very much for your answer.

I am checking now the Turbine control logic software program of Mark VIe. Unfortunately, it is program software, not the control logic like SAMA language, it is Mark VIe program so quite difficult since I still don't know how it control the Turbine.

With the DCS system, it is very easy to understand. Logic, loop like PID control. That all.

But the Mark VIe, they use many block definition by user and no document help. Important part of the Turbine control is Governor control. I want to know the concept first, then I try to read with program.

Any help, could be appreciate.

 

N.V.Q,

You say you're accustomed to reading SAMA diagrams; everyone, at some point in their career learns some method first, and for the majority of them that's the one they like the best for the rest of their career. (I know that's not true of everyone, but it is for the majority of people in this field.) It all boils down to what one is comfortable with, and for those who spend the majority of time working with the first programming method they learn they seem to always like it the best.

I find it easiest when trying to learn a new programming method to find an input or an output and follow it through the program/logic/sequencing/application code/function block diagram--whatever it is. In your case, you seem to want to understand how servo-valve outputs work--what drives them, how they are configured/programmed to operate. So, go to the PSVO pack in the hardware "window" pane, drill down to a TSVO card, find the name of a particular output and then start working backwards from there.

In ToolboxST you can right-click on a block (an algorithmic or a primitive (primitives are ADD, SUBTRACT, MULTIPLY, DIVIDE, SQUARE ROOT, etc., types of functions)) and a window will pop up. One of the selections in the pop-up window should be 'Block Help.' If you click on 'Block Help' you should be able to find more information--should be.

Unfortunately, some "blocks" are macros--which are composed of multiple primitives and some other higher-level algorithmic blocks--and the programmers of these macros are not required to create a 'Block Help' description of the macro for others to use to understand how the block works.

HOWEVER, one can open the macro and all of the individual components of the macro will be visible, they just won't have the actual signal names which the macro operates with shown in the "under macro" level. This makes troubleshooting in the middle of the night very difficult and stressful, but if one has time to analyze and understand the components and can visually apply signal names to block elements (inputs and outputs) it is possible to work through the macro functions. I recommend making a screen capture of the macro elements, printing the screen capture (by pasting it into MS-Word or MS-WordPad and then printing to a local or network printer), and then using a pencil and highlighter to make notes as one works through the macro. It's about the only way I know of to be sure one accounts for the "ins and outs" and the internals of the macro being examined.

I also sometimes pick an input and follow it into the application code and see how it's used--something I'm pretty certain is associated with a function I'm trying to understand. In your case it might main steam pressure, for the Inlet Pressure Control function. Or the input from the megawatt (Load) transducer, for the Load Control function.

Again, if you have the manuals provided with the turbine and auxiliaries you should be able to find some reasonably helpful GE publications about various control functions. As always, <b>read any GE publication for <i>>>>intent<<<</i>--not for content.</b> By that I mean--don't read any written documentation/publication believing that it describes <b>EXACTLY</b> how your turbine operates. Rather, read it for a generic description of how your turbine is <b>intended</b> to operate, and then apply that information to the application code running in the Mark VIe at your site.

The only real "documentation" that describes <b>EXACTLY</b> how the turbine at YOUR site operates is the application running in the Mark VIe of the turbine at your site. It's not in sentences and paragraphs, but if you know how to read SAMA diagrams, you already understand that it's a "language" that can be used to cause desired things to happen in a logical fashion. The FBD (Function Block Diagram) programming method used by GE for the Mark VIe is <b>NO</b> different--it's just that you're not accustomed to it, and you're going to have to spend some time getting accustomed to it.

I also believe you will find that many of the block help functions have very good descriptions (those with block help!) that can be used to follow signals through the block. Inputs are almost always on the left side of the block, and outputs are almost always on the right side of the block (so they "read" from left to right, input to output). I have worked with several people over the years who loathed the GE blocks and relay ladder diagrams--but when they learned how to read and understand the signal names and how to follow signals through the blocks they admitted--reluctantly--that they liked the GE method of documenting sequencing/application code better than what they were previously familiar with. (I'm presently working with some Woodward GAP (Graphical Application Program) logic--and I can tell you it's HORRIFIC--all they have are rectangles with inputs and outputs (which can be and are on any side of the rectangle) and then one has to find a manual which matches the version of GAP they are using to understand exactly what happens inside the rectangle, and it's usually just a simple paragraph without much of a description--and almost never any kind of graphical portrayal of what's happening. Which makes me continually ask, "What's so 'graphical' about this application/program??!!?!!" It just drives me insane--and I was already about two-thirds of the way there and don't need any directions or help getting the rest of the way there!)

Lastly, in my personal opinion the Mark VIe training courses offered by GE are very lacking in the basics of reading and understanding FBDs and blocks and even basic relay ladder diagrams (of which a lot of the logic/sequencing for auxiliaries of the turbine is composed--using Function Blocks). They just ass-u-me that everyone can already read and understand relay ladder logic and Function Block Diagrams, and do not go into the depth or detail required for even basic alarm troubleshooting.

I think you will find some of the blocks have PID control elements inside them, or are composed of other elements with a PID block. The thing that confuses many people about GE control system servo-valve outputs is that the loop (position) is closed at the I/O card (I/O Pack, in your case) level--not in the application code (program). It's just a different way of thinking about loops, but it's actually very effective and quite reliable--and MUCH faster than if it were done in the application code/programming). The regulator loops in the I/O Packs run at 100 Hz or even faster in some cases, which is as much as four times faster than application code (running at 40 msec).

We can try to help here, but my experience with steam turbines is pretty limited. JFB and others, while maybe not so familiar with Mark VIe, can provide a lot of information and detail about how control should be done and help with the low-level details. So, we can try to answer questions here, but I'm afraid you are trying to get to a really detailed understanding--without having had the benefit of observing what happens during commissioning which can be extremely beneficial.

Hope this helps!