Wind Turbine Grid Problems??

[Eastender]

Wondered if anyone on here had any ideas with regard to our issue.

We have 2 Gaia turbines (11Kw each) which were installed in August 2011 and March 2012 and both have performed very well overall.
However, over the last 18 months/2 years we have an increasing number of cases of the electrical trip switch tripping which cuts off power to the turbines and they stop until the trip switches are reset (G59??)
This tends to happen in windy weather and is damned annoying!
This week, the same happened again but for the first time, after resetting the trip switch, as soon as the turbines started again the switch tripped again. We tried 5/6 times over the course of the day with no success. Interestingly it was a windy day and both turbines were starting at the same time and getting straight into production before tripping the electricity supply.
Next day was less windy and we tried again. This time one turbine started quite slowly and gently well before the second one and as of writing this they are both still turning without any problems and producing electricity.

My question is this (I am not an electrician!), is it possible that the "grid conditions" have changed over the last couple of years (there have been more (500kw) turbines installed in our area (within sight of here) over the last couple of years and the electricity cable for a large off shore installation comes ashore here too)
When we installed 5/6 years ago we had to use extra heavy duty cables from the turbines in order to combat quite a high inherent overvoltage in the local grid going past our property. At the time the DNO had refused to tap down the transformer as the voltage was required to provide a suitable supply to properties further from the transformer than us.
Is it possible that our local grid supply is now running at a higher voltage than it was 5/6 years ago and is thus making it harder for us to export onto the grid thus triggering the trip/G59 much more often than it used to?
If so, what can we do about it?

As I stated at the beginning, I am not an electrician so if none of this makes any sense then I apologise but any ideas would be most welcome.

Thanks in advance.

 

[akaPABLO01]

Inside the g59 is a monitor relay that should display the phased voltage.

You should monitor and mark down the results. If you don't want to adjust the trip settings then you'll need to call out the manufacturer to do this. I've dealt with g59 manufacturers and they aren't cheap as the kit they use can cost about 10k and they damn well make sure they get a good screw from site attending, maybe overnight costs too.

There should be contact details inside, call them and ask what the trip voltage under/over is set at. They may have no clue but it's worth a try.

Details of the last trip should be displayed in the relay also.

If you're brave enough, adjust the trip settings.

You are right, it is high grid voltage and adding 2/3 volts on overvoltage should stop the g59 tripping. But that's whether you want to do this or pay anything upward of £750 I suspect.

You could also argue the fact it has been set up correctly to handle your grid connection?

Edit; it'd take no more than 1 minute to adjust the voltage trip settings, g59 manufacturer can tell you what to press at g59 unit

 

[sjt01]

Check your line voltage also. If phase to neutral is over 253, then the DNO should alter the transformer tapping as it is illegal for them to connect you over this voltage. If all your local turbines are going flat out in windy weather, the voltage could well rise to that level. They may insist on monitoring voltage for a while, which will probably be over a period of still weather when the voltage stays within limits.

Our G59 relay stores a log of the causes of trips, so if yours does this then look back at the cause of the trip. Over voltage is obvious, ROCOF and vector shift probably indicate glitches in the supply.

If we want anything changed on our G59 relay (170 kW AD CHP) it means getting the test engineers (John or Eddie) to do the settings, and the DNO representative to witness it and sign it off. That gets expensive.

Stephen

 

[DC21]

Every DNO is different, which is yours?

I've found ENW quite good at retapping to reduce high voltages, NPG on the other hand can be difficult - on the last site we had difficulties, they insisted on 1 week of voltage monitoring without generation to show the voltage was over 253V!

 

[sjt01]

We are on UKPN, they will eventually do a tap change but the complaint needs escalating first.

 

[Eastender]

Thanks everyone for your suggestions and useful info on this.
It turns out after a long and protracted investigation that I was barking up the wrong tree, albeit in the right plantation! To cut a long story short, the G59 settings were the problem but overvoltage was not. Our DNO (Northern Power Grid) could not have been more helpful and we had a voltage recorder on site for over a week. They were then happy to share the data with our engineers. Unbeknown to me there are a couple of things called ROCOF and Vector Shift (thanks sjt01) which are also settings within the G59 relay. It turns out that it was these settings which were causing the G59 to trip not overvoltage. These have now been adjusted and we have had trouble free operation through quite a bit of windy weather ever since. Our engineers are Sustainable Energy Systems (SES) and I would recommend them to anyone.

 

[Still Farming]

Funny how this happens as said too windy for wind turbine ?
Maybe as said vac surge and gusting winds maybe worst.
Steady strong wind seems ok ?