I assume that the logic behind retaining the original Ybus is so that you do not have to refactor the matrix. MATPOWER does not include code to compute the AC PTDF or LODF, but I imagine it would assume some matrix factorizations.
-- Ray Zimmerman Senior Research Associate 419A Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Mar 4, 2012, at 11:45 PM, jigna pandya wrote: > Respected Ray sir, > i ask the question in detail. > i want to determine ATC considering line outage and want to find ACPTDF > considering line outage. > the steps involved in determining AC line outage distribution factors are > (1)execute load flow > (2) for simulation of line outage (say line k which is connected between bus > r and s), we make STATUS of line k as zero, which will change the elements of > Ybus. > but according to theory, in order to retain original Ybus, a line outage is > simulated by considering two fictitious generators connected at buses r and s > whose injected powers are equal and opposite. thus net power flow in the line > becomes zero. > also a fictitious line is connected between bus r and s whose parameters are > same as that of original line k. As a result Ybus remains unaffected. > so my question is : Why we are interested in maintaining same Ybus? is there > any computational advantage? > Because if we just make status zero, then it will make some entries of Ybus > zero, which will on the contrary , reduce computational burden. > > thank you > > --- On Fri, 3/2/12, Ray Zimmerman <[email protected]> wrote: > > From: Ray Zimmerman <[email protected]> > Subject: Re: PTDFs > To: "MATPOWER discussion forum" <[email protected]> > Date: Friday, March 2, 2012, 11:11 AM > > I'm not sure I understand the question. There is less computation involved in > calculating the PTDF for a system with a line out than for the same system > with the line in service (i.e. one row becomes all zeros and does not need to > be computed). If that doesn't answer your question, you'll have to try > rephrasing it. > > -- > Ray Zimmerman > Senior Research Associate > 419A Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > > On Mar 2, 2012, at 1:32 AM, jigna pandya wrote: > >> Respected Ray sir, >> Does the outage simulation of a line produce any computational burden in >> calculating PTDF? >> thanks >> >
