half hourly import

[marconi]

Vestas V27 - 225 kW - Boythorpe Wind Energy

A 225kW medium sized wind turbine suitable for powering larger farms, community projects and commercial properties.

www.boythorpewindenergy.co.uk

Do you have the Vestas V27 which has a rated output of 225kW and sold to farms in the UK? You could ask them about the energy consumption of this turbine and whether indeed there might be something wrong with yours.

(As I have got interested - and no doubt some others too - would you mind keeping us posted on what you find out please?)

Without boring you from what I have read up it is well understood in the wind turbine industry and users that they do consume energy/power when idle and when turning even if not generating. This is not surprising when one studies the actual technology and engineering rather than the 'for the lay person' idealised description of them which only mentions usually their maximum rated wind generated power.

One of the metrics for renewables is annual energy yield in MWh but I have not bottomed out if this takes into account annual energy consumption.

 

[marconi]

The professor is at Exeter University.

IT Server Security project | Exeter IT Services | University of Exeter

emps.exeter.ac.uk

This is the content of my email to him:

Dear Professor Abusara,
Please forgive this 'out of the blue' email but I have a simple question I have not been able to find the answer for myself.
It concerns grid connected wind turbine generators using ac asynchronous alternators, either on or off shore.
I understand how they generate electricity and feed this into the grid when the wind blows. My question is about when there is no or very little wind (below the cut-in speed?) - do the rotors keep turning by being powered by the grid ie: motoring?
Yours sincerely
Dom A-H CEng MIET

 

[Lucien Nunes]

Meanwhile, I turned this up - I caution it is from a site biased against wind but the remarks made are true enough about how a large wind turbine draws energy from the grid.

Your caution is well received - I would ignore that piece completely. There are guesses and assumptions, some of which are irrelevant or simply wrong, but all of which purport to demonstrate how wasteful wind turbines are. I do not think the writer has a clear grasp of the technicalities or deliberately confuses them to make his point. I won't bother picking it apart here, nor studying the references although some of those may well be sound.

 

[Gilest]

We met these arguments during planning.
It’s amazing what sort of arguments appear !

 

[marconi]

What matters is the net contribution over the long term (eg a year) of energy to the grid by the turbine, energy which otherwise would have been generated in full or part by fossil fuels.

I suspect that to some folk wind turbines are rather like pylons - you either see them as objects of beauty with benefits or simply an eyesore on the landscape. Items of beauty to me in both cases.

 

[marconi]

Thinking on the intermittent nature of your charging problem....

The Vesta V27 includes switchable power factor correction under computer control because the generator has two selectable windings depending on the power output..

See para 3.12 and 3.17 of

https://www.mwps.world/wp-content/uploads/2010/09/Vestas-V27-Technical-documentation.pdf

Some HH meters record kVAh as well as kWh and some energy suppliers charge for reactive or apparent power consumption and not just kWh.

Blog: The Easy Guide To kVA Levels / Capacity Allowance - Inenco

Businesses with sites affected by P272 may need to understand how the move to half hourly settlement affects their capacity allowance.

www.inenco.com

See: https://www.edfenergy.com/sites/default/files/b2b-guide_to_reactive_power.pdf

Thinking more on the intermittent nature of the 'spikes' in half-hourly consumption, it would be very helpful to know:

a. the units and amounts ie: kW? kWh or kVAh?
b. how is the data from the HH meter returned - through the internet automatically?
c. does your electricity bill show a charge for kVAh and/or reactive kVArh. I am making a distinction here between kWh - actual power consumed and kVAh - apparent power which is higher and comprises of actual power plus reactive power which is not a net transfer of energy but rather a tooing and froing between the supply and certain types of load such as motors and generators.

 

[Lucien Nunes]

See: https://www.edfenergy.com/sites/default/files/b2b-guide_to_reactive_power.pdf

As an aside that EDF e-guide is pretty rubbish! Its first factual error occurs at the third word and there's a further error before the end of the sentence. It doesn't get much better. Can anybody make sense of this:

Where the first step is 50%, the Local Network Operator does not charge for reactive power for the first 50% of units (kWh). Charges therefore apply when the difference between the total units recorded on the reactive register (kVArh) is less than 50% of the total units consumed (kWh).

I know what it is trying to say, but if I didn't, I'd be more confused than when I started.

 

[marconi]

You point out a typo first.

Second you quibble I think about the use of 'difference'. AP = TP + RP when I was at school so RP =AP - TP - a difference. You know why I have written them in bold. AP is apparent power, TP is true power and RP is reactive power.

On the third point you may be tired. An example calculation was provided. But yes, 'more than' instead of 'less than'.

Suggest you contact the author of it.

 

[Lucien Nunes]

Not wishing to sidetrack the thread, my first point was that KVArh is not a unit of power as implied. The second, yes, this is aimed at non-technical people with no knowledge of the underlying maths who are unlikely to interpret correctly the ambiguous 'total power consumed.' Then, apart from the sign issue, the difference between which two variables specifically; the kVArh reading and what?

They were just three of many quibbles picked at random. I could have complained about the meter that consumes 2.5MWh, the number agreement error between 'most electrical equipment' and 'create', the non-sequitur 'reactive power therefore generates...' etc. More importantly, it does not explain reactive power coherently, nor why the charges it attracts are computed in the way they are, nor differentiates between power factor and efficiency (a common source of confusion.) Power factor supposedly 'indicates how effectively electrical power is being used.' Grr.

 

[marconi]

Suggest you contact the author of it or re-write it for EDF (for a fee).