Problem with Matlab - GA to solve Transmission planning problem

Dear Sir,

I am trying to use genetic algorithms ("ga(fitness,.....)") command function to solve power transmission planning problem.

The basic steps are (a)to perform power flow calculation using MatPower=>then (b)compute related parameters used as the constraints required to be input to the ga function=>(c)starts GA...(repeats a,b&c until max. number of generation is reached)

My problem is that as the candidate solutions (number of transmission lines to be added to the transmission system) that generated by GA function each time will vary the value of some of the parameters of the constraints inside the GA function input, how can I update the parameters within the ga function but not just use the same constraints values in the whole process of GA?

Thank you if anyone can help.
Student from HK