Re: [femm] Modelling a three phase short circuit of a Synchronous machine.

[David Meeker <dmeeker@xxxxxxxxxxxxxxxxx>]

"C.Prem Kumar" wrote:

> Hello there !
>
> I am interested in simulating a balanced three phase short circuit of
> a Synchronous generator for determining the Short Circuit Ratio. Can
> any one help me on how to go about it ?
>
> Many thanks in advance.
>
> C.Prem Kumar

You can't really do this with femm right now. Simulating this test would
actually require some sort of stepped integration over time in which the
rotor is spinning--femm only does magnetostatic problems and harmonic
problems in which the physical configuration is fixed. Since the source
code to femm is available, it would be possible to "hotwire" the code to
do time transient problems, but it would require some fairly extensive
modifications. I'm hoping to get around to adding this sort of
capability at some point, but I probably won't get to it in the near
future.

However, I understand that the main purpose of this sort of short-circuit
test to infer the machine's reactance. With femm, you can set up a
series of magnetostatic simulations and determine inductance directly for
various rotor orientations. This might allow you to get the information
that you are after without actually having to perform the short-circuit
test on the numerical model.

Dave.

N.B.--A sort of interesting paper that examines performing a
short-circuit test on a synchronous generator via finite element
simulation is: S. Nabeta, et al., "A non-linear time-stepped
finite-element simulation of a symmetrical short-circuit in a synchronous
machine," IEEE Transactions on Magnetics, 31(3):2040-2043, May 1995.


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