Do wind turbines using AC/DC/AC topology increase short-circuit power? 1

[Bronzeado]

Dear all,

Do wind turbines using AC/DC/AC topology increase the grid short-circuit power?

Best regards,

Herivelto Bronzeado

 

[davidbeach]

Yeah, but probably a fault current of about 1.2-1.5 per unit. Probably can be ignored for pretty much everything except withstand ratings.

 

[Bronzeado]

Thank you davidbeach,

In this case, could I consider that a wind farm with 50 wind turbines running with this configuration (AC/DC/AC) would increase the short-circuit level by 50x1.2-1.5pu?

We had a problem in a substation busbar (69kV) and we suspect that the wind farm has contribute to the increase of the short-circuit level. But we could not prove that sofar. It is connected 80km away from our substation, being fed by a single line of 69kV.

Do youy think that the influence of that wind farm is considerable?

Regards,

Herivelto

 

[alehman]

You need to contact the turbine/converter manufacturer to determine the actual fault contribution. Then you need to do a proper fault current study to determine the affect at the substation.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[Bronzeado]

Thanks Alan,

The wind farm is embeded in the distribution system and we, as a transmission company, have no contract with them.

My question is a general question as I think that the converter limits (or cut) the current during a short-circuit in the grid.

Best regards,

Herivelto Bronzeado

 

[alehman]

One particular 100 kW model for which I happen to have specs has a fault contribution of 1.0 pu. I don't think it is safe to generalize however.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[Marmite]

Bronzeado, you may find the attached paper of interest.

http://webarchive.nationalarchives....newables/publications/pdfs/dgcg000270000.pdf/

See page 52 onwards.
Regards
Marmite

 

[tlrols]

What you describe is commonly referred to as a "Type 4" machine. Said machines do not source fault currents past a vendor supplied limit, usually (as David Beach says) somewhere around 1.2 pu.

The last integration study I performed (about two days ago) we were supplied vendor data that showed inverter limits right at 1.2 pu fault current. As a worse case you could assume 1.5 to 2.0 pu fault current, but that really is a poor substitute for the proper information.

 

[Bronzeado]

Thank you all for discussing this matter and thanks Marmite for your valuable link.

Could we conclude that a machine with power electronics coupling does not increase tha shor-circuit level regarding to break current?

In other words, should we be worried about changing our circuit breakers in a substation when a wind farm with electronics coulpling machines is connected to that substation?

Regards,

H. Bronzeado