I'd like to enquire if anyone has had any problems or increased frequency of nuisance G59 tripping in the last year.

Even with repeated re-testing of relays we are still experiencing a high level of trip events at a number of sites across the country.
One particular site has had 100+ events since May.

At present, remotely, from an alarm log perspective I can't differentiate between vector shift or voltage (this is to change!) and the relays have no log. Most of the events happen when the system is not in parallel and are not a problem, but the ones that happen during a STOR run cause a cancelation of the run and subsequently affect the systems ability to meet its contractual obligations.

I have approached the DNO's and I'm waiting replies
I'm wondering if the settings can be adjusted to suit (subject to approval from the DNO)

Chris Taylor

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Is the search for the Higgs Boson mass hysteria?

Hi Chris, a couple of things would help diagnosis
Are the systems LV connected?
Which relay are you using?
Are the relays set for G59/2 which allows a wider voltage window than G59/1?
At the site with the numerous trips have you checked that the 'nominal' system voltage is the same as when the relay was originally set up.
G59 relays we find are extremely reliable and are never asked to go back and retest them [rightly or wrongly]
If you can prove to the DNO what function is causing the tripping they are likely to be sympathetic and allow an adjustment to the setting.
[ They might insist on a retest]
Is there a change in th system voltage with the genset running and with them off-line
Regards 944se

944se

The sites are all LV, the relay is the Woodward MFR11, the settings are G59/2 with vector shift and not ROCOF.

Nominal voltage is seems OK and stable both importing and exporting, well within limits but we are currently putting power quality meters at three sites and using a spare contact from the G59 relay programmed for vector shift into our PLC to see if that the problem.

We are planning to install some non functional relays at these sites as well but with the vector shift at 8 deg rather than 6 deg to see what happens.

Before this year and with G59/1 using ROCOF, I can't remember a nuisance trip

We shall see what happens.

Chris

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Is the search for the Higgs Boson mass hysteria?

Chris, that all seems ok. The only thing I would mention is that unusually on the MFR 11 you can set the vector shift for 3phase or single phase operation. We always use 3 phase setting as we find single phase is too sensitive. I cant recommend you revert to ROCOF as the DNO will be looking for settings in the order of 0.125Hz/ sec which we find will give nuisance tripping.. I 'll be surprised if you find fault with the MFR relays. The 6 degrees should be OK
Regards 944se [interested in the outcome]

944SE

Thats interesting, thank you. As I recall ,we have the vector shift set for both 3 pahse and single phase, I'll look at G59/2 to see if we can remove that element.

Thanks again.

Chris

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Is the search for the Higgs Boson mass hysteria?

Chris, you don't need to set both,in fact the MFR11 is the only common relay that I can think of that gives you the choice.
Regards 944se

If your trips are happening when not in parrallel then why not disconnect your G59 protection when in Island? Assuming you have no equipment issues.

Al

Chris, on the MFR11 terminals 5 and 6 give a blocking function which ensures the relay is in active until the system is in parallel. this should have been set up originally when it was decided the relay should trip the mains. One word of caution is that there are various versions of the MFR11 and you should check your instrument Serial Number with AVK in Maidenhead to see the blocking function is available on your relays..
944SE

AL, 944SE

For our sites we use one contact to directly trip the mains but through mains ACB and Generator ACB NO contacts, so both have to be closed for the trip to be active. We use a second output direct to our monitoring system and this is why we record non-parallel events.
Some DNO's don't like the blocking function and prefer us to use the volt free contact solution and try to keep some sort of continuity in the systems.

Chris

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Is the search for the Higgs Boson mass hysteria?

Chris,

My colleagues Campbell Booth and Adam Dysko here have done a lot of work on ROCOF and VS relays, comparisons and setting, and even a prototype replacement based on phase angle drift which I believe is being trialled by Alstom.

http://banking.contify.com/sto...d-protection-28305984

There is quite a lot of work ongoing about appropriate ROCOF settings etc, both in academia and with organisations like National Grid, and recent experience in Ireland is highlighting such issues, with ROCOF settings perhaps having to reach 0.6Hz/s to avoid nuisance tripping soon, due to reduced system inertia.

There might be some mutual interest in looking at this together, if you want to contact them directly:

Campbell Booth (campbell.d.booth@strath.ac.uk)
Adam Dyso (a.dysko@strath.ac.uk)



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Dr. Andrew Roscoe

http://personal.strath.ac.uk/andrew.j.roscoe

Sorry, I forgot to add these two other links that may be of interest. There will be many others, too.

http://www.sedg.ac.uk/DGSEE%20...Year%202%20Report.pdf

and

http://ieeexplore.ieee.org/xpl...rnumber=4159954&tag=1

Reducing unnecessary disconnection of renewable generation from the power system



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Dr. Andrew Roscoe

http://personal.strath.ac.uk/andrew.j.roscoe

Try talking to George McDowell at ERA he has been poking round G59 relays for more years than he and I care to remember. They have always been problematic, and probably always will be!

http://shop.era.co.uk/images/course_pdf/DistGen.pdf