DNO turning off systemsDno turning off systems

[moggy1968]

UPDATE:

Just spoken to the DNO (uk Power networks). They say it is there policy to not change the voltage settings if they are within guidlines. They will give permission to connect to the gride but if the voltage rises above guidlines they will instruct you to disconnect. Apparently they do not bother to check that it is safe to connect to the grid, they just give permision and then screw the customer if it causes a problem.

hmmmnn, thats helpful then!

 

[Morgan keith]

We had a similar issue on a job but after speaking to the DNO nicely they came and measured the supply voltage at 251V and agreed they'd give all the property's supplied off that transformer 2 weeks notice of the power going off for a few hours and then came back and lowered the voltage. All works fine now.
Most importantly though, we did another job last week and were worried about the grid voltage as is was high but coincedently the customers had a power factor correction unit installed at the same time to 'lower their energy bills' and after that being installed the voltage went down from around 252V to just over 240V! Maybe this could be another solution? Although I'm not too clued up on PFC units, maybe someone else would know??

 

[MickF]

PFC's I think you'll find are the same as VO's a drop to only 240V consumer sided of the 'PFC' is not very good it should ideally be in the range 220V-230V ... if the 240V is supply side, then it's just coincidence. The PV will still need to be connected supply side of the 'PFC'

 

[Morgan keith]

PFC's I think you'll find are the same as VO's a drop to only 240V consumer sided of the 'PFC' is not very good it should ideally be in the range 220V-230V ... if the 240V is supply side, then it's just coincidence. The PV will still need to be connected supply side of the 'PFC'

Well the PFC was connected to the system in parallel (Protected by and MCB) and it lowered the supply voltage in the DB.
Coincence, maybe. But would have to be very coincedental

 

[Gavin A]

UPDATE:

Just spoken to the DNO (uk Power networks). They say it is there policy to not change the voltage settings if they are within guidlines. They will give permission to connect to the gride but if the voltage rises above guidlines they will instruct you to disconnect. Apparently they do not bother to check that it is safe to connect to the grid, they just give permision and then screw the customer if it causes a problem.

I'd check ENA's position on this. The guy who's email addy is on the main page with all the guidance on it gave me a straightforward answer to a query inside a day last time I emailed him, just make sure you approach with a straightforward question.

after that there's Ofgem.

 

[xiaoneitie]

I've never noticed that. Have you asked OFGEM for their advice?

 

[SouthernSpark]

This may be a stupid question, but would installing a battery pack not help this situation? It would give the power somewhere locally to go and would save money in the long run. I know the outlay may be high initially, but if its a case of losing £30K or installing a large Ah Battery pack and using the power produced through the day, in the evenings, plus having the inverters working constantly so you can earn the maximum FIT, the benefits may be worthwhile.

On the other hand I am no engineer and have no idea whether this is actually feasable. Its just an option Im hoping someone on here could either say is possible or eliminate for whatever reason.

 

[st3ve]

First, I'm no expert, but I'm sure that I have read about problems with 2 inveretrs 'affecting each other' in something like the way you described.

I can't remember where, but I'll try to revisit some other sites I've been on in the hope of forwarding a link

 

[Worcester]

Here's an extract from the contents of a G59/2 Connection approval letter we got from UK Power Networks:

UK Power Networks (operations) Limited highlight that the maximum voltage limit for the network at which the generation is to be connected is 253/440V. If the generating plant causes the voltage to raise beyond this level it could ultimately result in the nuisance tripping of the generator sets or an unsafe condition on our distribution network. If the latter is found to be the case, we may require the customer to reduce the level of export or use our statutory powers to disconnect the generation plant altogether. If nuisance tripping of the generator sets occurs that the client or consumer finds unacceptable, this can be resolved by UK Power Networks (operations) Limited undertaking a tap change at the local distribution substation, if this is requested by the client, consumer, you, your company, the installer, electrical contractor or any other party, then it will be chargeable.

Definitely working to the letter of their powers as opposed to other DNO's that we often work with that are more flexible and understanding, givien the area they cover, perhaps UKPN's network has been hammered by so much wind generation, they are less open to variations?

Fortunately we just visited 15 sites within UKPN's area and never got an incoming voltage greater than 241V - perhaps just lucky!

 

[moggy1968]

what would they charge for retapping?

 

[Worcester]

Anything from a couple of hundred up to a few thousand, all depends, also in some areas, you'll find that the transformers are already on Tap 1, so would need to be replaced, that would be a siginicantly greater cost, and they don't like doing that becase of potential knock on effects if they decide to lower the output from the central transformers ...

 

[sedgy34]

I have recently proposed a 30 kw to the DNO they said max allowed on there network is 25 kw and if we want to install the 30kw it's going to cost £17000 to upgrade there equipment.

 

[Gary K]

I have recently proposed a 30 kw to the DNO they said max allowed on there network is 25 kw and if we want to install the 30kw it's going to cost £17000 to upgrade there equipment.

So if you install 25kw, whats stopping them asking you to disconnect at a later date because the input still causes problems in the future???

 

[moggy1968]

nothing it would appear, then you get sued and it's bye bye business, and all for margins at rock bottom at the moment!!

 

[sedgy34]

So if you install 25kw, whats stopping them asking you to disconnect at a later date because the input still causes problems in the future???

They have given us a confirmation letter for the 25 kw is acceptable