Hmmm, yes, unfortunately, I believe that the DC line implementation modifies 
things in a way that breaks the normal handling of other linear constraints by 
changing the number of generators. I'm pretty sure that simply adding 
additional columns of zeros to the right side of your A matrix to make it the 
right size should be sufficient. You don't need to add any rows.

-- 
Ray Zimmerman
Senior Research Associate
419A Warren Hall, Cornell University, Ithaca, NY 14853
phone: (607) 255-9645




On Mar 19, 2012, at 2:23 AM, Zhouxing Hu wrote:

> Dear Dr. Zimmerman,
> 
> I want to add additional constraints on only regular generators but not on 
> "Dummy" generators that created by DC line modeling. However, I got problem 
> of A matrix dimensions: 
> 
> Error using opf_model/add_constraints (line 102)
> @opf_model/add_constraints: number of columns of A does not match
> number of variables, A is 3174 x 3312, nv = 3888
> 
> The difference of 3888 - 3312 = 576 is exactly the number of "Dummy" 
> generators created by DC line modeling. But I don't want to add constraints 
> to those generators. I'm thinking of adding zeros, '-Inf' and 'Inf' to A, l 
> and u vector respectively. I'm worried about this would affect the 
> convergence or computation time. Do you have any better suggestions on 
> solving this? Thanks,
> 
> Zhouxing Hu

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