Undefined function or variable "xa" error message

Hi. As part of my research work, I am investigating the synchronous machine stability at low speeds. I connected the SI fundamental simulink blockset machine with exciter and speed input to a load. Before I simulating I have tried to carry out a load flow to get steady state using the powergui with no success! I keep getting the error, Undefined function or variable "xa" in the matlab window. Unfortunately I cant get past this error and its delaying my research considerably. Can anyone give me direction on this please.....Thanks.

Answer 1

[Fangjun Jiang]

In the Simulink model, press Ctrl+F, search where the variable 'xa' is used. Then assign a proper value to 'xa' in MATLAB Command Window, for example:

xa=1

[James [e-mail]]

Thanks for response. I have tried your suggestion and it doesnt bring out the undefined function or variable. I also tried to assign it the value 1 in the command window with no success, load flow still throws the same error. What baffles me is that it is an extremely simple circuit and shouldnt have such issues. I have also tried constructing afresh from blockset and the power gui keeps throwing same error. Anything else I can try?

[James [e-mail]]

I've just tried the same simple circuit with the pu standard synchronous model and the load flow/initialization works! The only problem is the larger network I was using the machine in is such that I need the SI units synchronous machine model and not the per unit one...argggh this is driving me up the wall!

[J Gunda]

Hi James...

I am trying to simulate synchronous machine per unit standard block. I have filled all the values but if I observe the waveform of voltage and current its not sinusoidal.

[J Gunda]

IF you have any idea regarding pleas help me...