You may try "nntraintool"

Dear Hatef

Not sure what your application but here is an AGC block for matlab

http://www.mathworks.com/help/comm/ref/agcblock.html

perhaps you can hook up ACG block before the ANN model

http://www.mathworks.com/matlabcentral/fileexchange/11202-automatic-gain-control

trust this helps

Gerro

ِDear Gerro Prinsloo

I mean Automatic Generation Control or Load Frequency Control not Automatic Gain Control but thank you very much for your help...

Sincerely 

Dear Thiyaneswaran Balashanmugam

If you have some simulated example please send it to me.

I don't exactly know how to use nntraintool for AGC problem.

Thanks 

Find the attched file, it may useful to u

thanks