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

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

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

(OP)
Dear all,

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

Best regards,

Herivelto Bronzeado

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

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.  

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

(OP)
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      

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

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.

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

(OP)
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   

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

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.

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

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.
 

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

(OP)
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

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