hi,

i want to ask if there is anyone who had an experience upgrade mark v to emerson ovation control system. is it working good?

thank you

 

I'm going to try to find contact info for a Customer representative at the site in this press release:

http://www2.emersonprocess.com/en-US/news/pr/pages/907-Fellside.aspx

This job was supposed to be complete in November, 2009. Ask about the turbine control retrofits as well as the total plant control upgrade.

Emerson should also be able to provide contact information for sites they have previously done retrofits on. They would likely be their better-performing jobs, but the questions you could ask could provide you with some very useful information.

Although I refer to an Ovation series controller below, the same questions should be asked of any company providing a control system for a GE-design heavy duty gas turbine application.

Remember, most any programmable controller can be configured and programmed to control most any device or process. The keys are how well the programming is done, and how well the hardware is adapted to the existing field devices.

So, you want to be asking questions about how well the transitions from Droop Speed Control to CPD-biased exhaust temperature control are handled. How will they program CPD-biased exhaust temperature control? Will it be a sliding curve that represents constant firing temperature, or will it be a fixed value of exhaust temperature?

It's not enough to say that the existing software and control schemes will be duplicated. If the people duplicating the existing software and control schemes in the new control system aren't familiar with the software and how it's documented in the old control system, and don't know basic heavy duty gas turbine fundamentals, they aren't going to do a very good job of duplicating existing functionality. A lot of the algorithms (blocks) in Speedtronic control systems are not documented in writing (though they are documented graphically in relay-ladder style). I've seen some very exceptional PLC programming with some very "trick" (excellent examples of smart, intelligent coding) code that just didn't meet basic requirements of smooth transitions from one mode to another and back.

When it comes to hardware, how will the hardware interface with +/-10 mA (bi-polar) electro-hydraulic servo-valves? Will there be any kind of converter used between the output of the Ovation and the servo? Is it proprietary or off-the-shelf?

How will LVDT feedbacks be handled? Will the Ovation be able to provide excitation (approx. 3.0 KHz, approx. 7.0 VAC RMS) and be able to handle the differential feedback directly? Or will there be converters that require external power to produce the LVDT excitation and then convert the differential feedback to 4-20 mA for the Ovation?

How will electrical overspeed be handled? It's presumed your units have an electrical (electronic) overspeed in the existing turbine control system (at least one), and there may be a mechanical overspeed bolt on the turbine(s), or a second, independent electrical overspeed in the turbine control system. How will the Ovation control handle the overspeed(s)? If you require a second, independent electrical overspeed, how will the Ovation system accomplish that?

Flame detection is likely currently accomplished using Geiger-Mueller type flame detectors (usually manufactured by Honeywell). These require 335 VDC for proper operation, and feedback circuits must be able to handle high-frequency 335 VDC feedback. How will the Ovation interface with these flame detectors: directly or with some kind of converter?

Vibration monitoring is another issue. Seismic vibration pick-ups usually have very low outputs (on the order of 100- or 150mV/inch-per-second). Will the Ovation be able to directly interface with the existing seismic vibration pick-ups or will some kind of converter be necessary?

If your unit uses any kind of injection (NOx emissions reduction or power augmentation), how will the programming for that be done?

Ask to see typical electrical schematic drawings for the control system they will be providing. Review them to see how the existing turbine field devices and instrumentation are interfaced and connected to the Ovation system they will be providing. Ask questions of Ovation about anything you don't understand.

This is good that you are asking about others' experiences. The questions you need to ask include not only the ones above, but, questions about execution of the retrofit and commissioning.

Was the removal of the old system, installation of the new system, loop-checking and commissioning done on time and without a lot of issues requiring remote assistance (either via phone or Internet)? Was it well-planned and smooth, or was it haphazard and not well-planned, not well-documented, or well executed?

These are good questions, and questions which should be asked of any references you are given. Ask Emerson for a reference for the Sellafield Fellside job in the press release above, which should be a very recently completed job.

These are questions to ask of both the supplier of any turbine control system, as well as the purchaser of any turbine control system.

Remember: You're not just buying hardware and software. You're buying a <b>turbine control SYSTEM *and* installation and commissioning</b>. Make your evaluation on the system, the installation and the commissioning--not just the price. It's rumored that some suppliers are offering some very good pricing on turbine control packages these days, and one should be very keen to know what their past performance has been on other, similar jobs (not DCS retrofits; turbine control retrofits).

Remember, the installation and commissioning are extremely important and will be the thing that most people remember about a turbine control retrofit, and past performance with respect to schedule and execution of installation and commissioning is every bit as important as the control system and documentation. Be sure to talk to references, and inquire about the <b>entire package</b> and experience. Don't be afraid to ask tough questions, because the ones you don't ask will likely be the ones you'd wished you had!