Here are few questions that might be helpful in steering you toward a solution ...
- If you are convinced that you have the correct p.u. parameters for the transmission lines? Errors in the p.u. conversion could result in such problems? - If you are attempting to model an existing system, currently in operation, are you sure you are using voltage limits that include the actual normal operating point? - Are you missing any shunt capacitors used for voltage support? - Have you tried a simple power flow to see how far out of range the voltages are? - Have you tried using a continuation power flow to see if your operating point is beyond the point of voltage collapse? - Have you looked at FAQ #5 <http://www.pserc.cornell.edu/matpower/#pfconvergence>? Best, Ray > On Mar 30, 2015, at 5:12 AM, Eser Patrick <[email protected]> wrote: > > Dear MATPOWER community, > > I am currently building a transmission system database for an emerging > nation. When running an OPF simulation for this system, I encounter the > problem of massive voltage drops over particularly long lines. This is hardly > surprising, since some lines of the system are longer than 400 km. Combined > with realistic reactances per km, this yields high per unit X (and B) values, > and hence voltage drops. When I artificially reduce the reactance and > susceptance values, I am able to achieve convergence. > > My questions are: Is there a way of solving this issue, without tampering > with the X and B values? > > I have played around with the tap ratios, but unfortunately, these are not > within the parameters of the optimisation (i.e. they are fixed a priori). I > have also tried adding a fictitious “reactive power generator” at each > substation, without success. > > Any help would be appreciated. Thanks! > > Best Regards, > > Patrick Eser
