Inverter over-voltage fault

[Mylz_95]

Hello!

I have a problem with my recently installed grid tie inverter (wind, 3kw, single ph)
It intermittently (depends on the day) throws two faults:

Grid over voltage
Grid over frequency

It’s a 170m cable run to the meter (swa 5 x 10mm (paired L+N so 20mm + E)) then a further 50m to the transformer (we’re the only property on this transformer)

At time of fault:
Voltage at the inverter: 248v
Voltage at the meter: 250v
Frequency at the inverter: 50.1
Frequency at the meter: 50.0


We also have a couple of solar grid tie inverters (12kw) much closer to the meter, but the fault persists whether they’re isolated or not.

When they’re connected, the frequency and voltage at the faulty inverter increases by 0.08hz / 4v

250v seems a smidge close to the upper limit, should I speak to my DNO?
I’m yet to monitor the readings when it’s working fine, but in the meantime welcome any advice.

Many thanks!

 

[plugsandsparks]

If you are confident in your readings, getting the inverter installers back to calibrate the settings in the inverter would be a good start.

 

[UKMeterman]

Grid over frequency? Please let me know where in the UK are you and has the the DNO got you on a temporary generator?

 

[Mylz_95]

In Cambridgeshire. To be fair the ‘over frequency’ fault is very rare, but over voltage seems to happen every other day. The fault history shows voltages like 255V.
I called the dno out (UKPN) the engineer arrived quite quickly, who only measured 250v. He said while that is close to the upper limit, there’s nothing he can do unless it’s over 253v.
He also mentioned he gets this complaint quite often!

He said to call the solar installers out to make sure all the settings are correct, and left it at that.

Not sure what the way forward is.

 

[UKMeterman]

The issue is physics, you are going to get about a 4 volt drop on that cable with 3kw. Your supply is at 250v ish, the inverter end will see about 254.5V ish. You have also mentioned 12Kw of solar so total site export of 15Kw??? What has the DNO authorised and what is the external loop impedance L to N or PSCC of the supply? It is a three phase or single phase supply?