29 MVA generator excitation control: GE PLC or Basler 200N?

[TheCairn]

We are in the middle of purchaing a tubine and generator package and GE has proposed a Converteam PLC based excitation control solution instead of the Basler 200N that we have farmiliarity with. I could be wrong but as I understand it, Converteam in the past had an industrial computer based excitation controller but they are now going to convert the code so that it can be run on GE PLCs. With Converteam's takeover by GE, I guess they can get the GE PLCs at a good price.

Does anyone have any comments regarding a PLC based or the Converteam excitation control system (computer or PLC based) compared to a Basler? Features? Hardware? Likes? Dislikes?

Our tubine will be used to convert excess steam capacity to electricity for export to the grid.

TC

 

[catserveng]

I have not worked on this particular system, but have done a few PLC based systems, and personally found them to not be as robust and reliable as a dedicated digital voltage regulator.

A PLC based solution will require some additional hardware, like a voltage and current sensing module that will either convert to analog signals the PLC can read or bring the info in via comms. Will also need a high current/voltage driver module for the field output, since I don't know of any rack based hardware that would drive the needed output.

How about an interface for manual control, going to be done thru the PLC and it's associated HMI? Sometimes paging thru a shared HMI to get to the needed screen for the AVR in a hurry can be a real pain, hopefully whoever programs it will be aware of that (frankly not likely unless you bring it up).

What about the protections? The DECS 200 has a lot of excitation related protections tailored to a genset application, does the PLC based solution offer comparable protections with ease of settings and review? How about the event and waveform capture, will the PLC based solution provide the ability to get data back out in a usable manner?

I have some experience with the Allen Bradley CGCM, while made by Basler for Rockwell, and supposed to be like a DECS200 and a GPS100 relay plus a few other features rolled into one, with a dedicated tie into to a ControlLogix PLC, frankly I hate the thing. Can't do anywhere near the setup, troubleshooting, manual control and small changes sometimes needed to startup and tune a generator.

Personally I'd stick with a real AVR for a generator, especially that size. PLC based solutions can be very good, but greatly depends on how well the person doing the programming understands what you need to be able to see and adjust, and frankly, just haven't seen it happen yet, at least in my experience.

Hope that helps, Mike L.

 

[itsmoked]

Other points:

Basler has very good tech support. I've gotten them out of bed at 3AM and they took it with good spirits. Gonna get that out of Converteam?



Infrastructure cyber attacks are heating up and appear to be targeting PLC based systems. Using the 200N may completely eliminate that issue.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[dpc]

I honestly can't see any advantages to a PLC-based system in this application, only problems.

This is fairly simple control. Even the older analog AVRs still work well. The 200N adds a lot of additional capabilities, most of which are usually not really needed, but also allows communications via the serial port, which some people think they can't live without.

 

[TheCairn]

We are looking at two advantages: GE PLC is standard for our site and capital cost savings of ~40k. Your thoughts?

Is it often that an exciter needs adjustment in a hurry? Once they're setup for the system don't they just kinda work or not work?

TC.

 

[ScottyUK]

I'd go with the purpose-built AVR. The AVR is a small part of the cost of the overall machine, and in your position I would want one which has a decent pedigree and proven track record, and has had time to shake out any bugs or glitches in the design.

I wonder if you are thinking of the pre-history of Converteam when it was still CEGELEC? In those days the uP-based GemDrive was sometimes used as a field controller for large synchronous machines, often with a GEM-80 PLC operating alongside it performing other control functions.

There's also the Alstom MicroREC dating from around the time when GEC-Alsthom owned CEGELEC. It was, not to put too fine a point on it, a heap of crap.



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