AC powerflow has convergence problem in many scenarios which we all know. The DC powerflow converges for the whole system even if this system has one or many islands; however, if a system contains one or many islands the AC powerflow does not converge. Does this answer your question?
On Mon, Mar 23, 2015 at 11:44 PM, Ray Zimmerman <[email protected]> wrote: > I don’t understand approach (1). I don’t know why you say that DC power > flow implies you don’t have to keep track of islanding. How does the AC or > DC power flow make a difference here? > > Ray > > > > On Mar 20, 2015, at 6:08 AM, Bijay Hughes <[email protected]> > wrote: > > > > Hej all, > > > > I am modeling blackout in the US transmission lines system, and have two > approaches to do so. I do it with DC power flow, which means I don't need > to take care of islanding if I don't want to (although I am aware that I > need to take care of isolated buses for convergence reasons). I have two > approaches to do so: (1) do cascading failure simulation on whole system > each iteration, whereby one doesn't keep track of islands; (2) do cascading > failure simulation on the whole system to begin, see if islands are formed, > and run the same simulation on each of these islands, and repeat the > process exhaustively. In both cases, the powerflow converges as it is DC > flow. However, the results are not matching, and I am wondering why. Could > it be because of the difference in the number of slack buses? Because in my > approach (1) the system will only have one slack bus in each iteration, > however in my approach (2) the system will have multiple slack buses as the > matpower chooses slack buses for each island automatically, thereby my > system as a whole will have multiple slack buses. Is this the only reason? > Which approach is better, (1) or (2)? > > > > Best, > > > > BH > > > >
