Solar power plants 4

[slavag]

Dear Colleagues.
I'm locking for some fundamental documentation about utility size of solar power plants.
Point is not inverters or strings, issue is connection to MV level and auxiliary supply of inverters, optional configuration: ring, star, option of outdoor solutions, protection and automation.
Could you please recommended some good sites or books.
Thanks in advance.

 

[magoo2]

I would check with the Department of Energy site for info on U.S. installations.

 

[GEORGE2311]

The MV power network of large scale solar plants follows the same principles as in the case of windparks. Just consider that you have an inverter kiosk instead of having a wind turbine. The same with the substation protection and automation concept. The only think that is different is the solar scada, where if you like i can post some document suggestions mainly from vendors when i go back to work at Monday.

G.F.

http://www.engineering-services.gr

 

[magoo2]

You might also check with the following link which lists the major inverter manufacturers by country.

http://www.solar-facts.com/inverters/inverter-manufacturers.php

SatCon and Advanced Energy are big in North America. Usually the inverter manufacturer will want to brag about where they've supplied units. They also show the major configurations.

It's a starting point, but it's not as neat a package as what you asked for. Hope it helps anyway.

 

[slavag]

Thanks.
I have a lot of documentation from vendors of inverters ( ABB and Siemens).
GEORGE2311, btw, I not have experience with wind farm too .
I also finished design of some solar farm 1250kVA before few month.
Now is some big farm, about 10MVA, from technical point of view is not problem, my problem is more economical evaluation.

 

[Skogsgurra]

Hi Slavag
A question in return: How do you evaluate the benefits of static vs rotary grid tie inverters?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[prc]

In solar power plants inverters are connected to transformers with vector group connection of Dy5y5 or Dy11y11.These collecting transformers are connected to a step up transformer with connection Dyn11.

There is an IEC for Transformers for windturbine applications IEC 60076-16ed1.0( 2011-06),most of it will be applicable for transformers used with solar power plants.

 

[prc]

The following books also may be helpful:
1) 1999_ M R Patel_Wind and Solar power Systems_CRC Press

2) 2007_John D McDonald_Substation Engineering _Crc Press

 

[GEORGE2311]

If i were you, i will do the following (for a 10MWp):
1) Chose at least 7x1250kva kiosks assuming 13,5% losses(or external inverter packs)
2) Place each kiosk or external pack at the middle of each own pv panels field territory (after a lot of studies this configuration has less power losses)
3) Make a MV loop and use two incoming bays at the collective MV substation in order to reassure the production export to grid. 10MWp is quite big number to afford power discrepancies. In each kiosk MV distribution use one incomer and one outgoing feeder just to reassure that you can disconnect a faulty or under maintenance kiosk. The incomer and the outgoing feeder don't need to have protection (a lot of money) just install protection to the transformer feeder and of course at the two mv panels at the collective S/S. My personal opinion is not to bother about direction protections and discrimination between the kiosks.
Don't forget to foreseen at least one spare mv cable core. Normal feeding is done through one mv incomer at MV collective S/S.
That is exactly the design i followed in a 50MWp project.
Hope that helps.

PS: alternatively, you can use instead of two incoming cable feeders at the MV S/S just one with double cable box. In any case go for a loop.

G.F.

http://www.engineering-services.gr

 

[slavag]

GEORGE2311, thanks a lot again.
This is a classical solution, I'm used loops with RMU..
I see, you use protection only in the main breakers too.
I think about some fault indicators..

Gunnar, sorry, I don't understand your question.

 

[Skogsgurra]

You may not be aware of the rotary grid-tie inverters. Used for sites where qualified technicians are rare and lightning frequent.

The configuration is a PV field, a DC motor and a synchronous generator. The generator is connectoed to the grid and the DC motor excitation is controlled in such a way as to run at a voltage close to the sweet spot - usually the knee in the U/I characteristic of the PV field.

I have worked with quite a few such units, often several 1 - 1,2 MW units are connected together to form 6 - 10 MW plants.

Advantages are: No EMI problems (DC and synch generator - no PWM). Robust (tolerates a lot more lightning than a PWM inverter does). Simple (no expensive and hard-to-find experts needed).

I don't know about costs. But they are being used. So, it cant be too bad.

I was asking for your opinion when comparing solid state inverters and rotary inverters.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[GEORGE2311]

Maybe this is useful,...

G.F.
www.engineering-services.gr