I made a mistake in my last reply... Power generation limits are fixed and set beforehand....limits are only referencial....They are more useful in optimal power flow.
Branch limits are to check overloads... Sorry. Santiago 2014-05-08 16:22 GMT-05:00 Santiago Torres <[email protected]>: > When you run a simple power flow (DC or AC) you have fixed generation set > beforehand, so the power generation limits are only referencial in order to > check overloads (you have to check by yourself; Matlab does not provide > overloads checking). In both cases, the power flow will not converge if > there is no balance.. If you want to simulate cascading failure and see > what happens with the power system, you have to use a dynamic simulation > tool (these tools use differential equations to model the system). Matpower > cannot handle this kind of situation. > > Hope this help, > > Santiago > > > 2014-05-08 16:10 GMT-05:00 Christian Stiller < > [email protected]>: > > Hey Scott, >> to 1) >> I have had similar Problems. Matpower only recognizes Limits if you run >> an optimal Power Flow (rundcopf in your case, don't forget to set the >> generator costs) >> >> and as santiago said, if there is not enough power, the problem won't >> converge. (in my case I limited the branches and got some very very strange >> results (not converged), so unfortunately matpower was not the tool for me. >> >> to 2) >> maybe the fact that there is no solution as way of recognizing? >> >> christian >> >> Am 08.05.2014 22:50, schrieb Scott Proper: >> >> This partially answers my question. Note that I am using a DC power flow >> for right now, not an AC flow or OPF. >> >> So my questions remain: >> >> 1) How can I modify case14.m (or any similar problem) to cause this to >> happen? Currently Matpower doesn't seem to recognize Pmax on generators. >> >> 2) I need some way of recognizing when this has happened in a simulation >> and calculating the result. If a blackout occurs, how do I know? And what >> happens exactly in this scenario to loads, generators, buses, and branches? >> >> This is all in the context of simulating a cascading failure situation >> like the 2003 northeast blackout. >> >> Scott >> >> On 05/08/2014 01:39 PM, Santiago Torres wrote: >> >> In practice, when there is no balance between load and generation, the >> frecuency of the system drops, and if you dont disconnect load, a blackout >> occurs. >> >> In that case, the simple power flow does not converge. >> >> The optimal power flow will converge only if there is enough power from >> some generator to satisfy the demand. In that case, the power generation >> is rescheduled by the optimal power flow algorithm. >> >> However, load and power generation balance is a requeriment in order to >> get the power flow (or optimal power flow) converged. >> >> You can refer to a power system textbook. >> >> Hope this help. >> >> Santiago >> >> >> 2014-05-08 15:21 GMT-05:00 Scott Proper <[email protected]>: >> >>> Recently I have been experimenting with using Matpower and rundcpf() >>> to simulate cascading branch failures and islanding. One question that has >>> occurred to to me is what happens when there is not enough generator >>> capacity to satisfy the loads at all the buses? I have had little success >>> figuring this out on my own. To this end, I have two questions: >>> >>> 1) Is it possible to modify a case (i.e. case14.m) to create a shortage >>> of generator power? My attempts to do this have failed. Turning down Pmax >>> doesn't seem to limit generator power. >>> >>> 2) How does Matpower handle this case? Is it possible to measure the >>> satisfied load when there aren't enough generators? >>> >>> Thank you, >>> Scott >>> >> >> >> >> -- >> Dr.-Ing. Santiago Torres >> IEEE Senior Member >> >> Power Systems Researcher >> >> >> >> > > > -- > Dr.-Ing. Santiago Torres > IEEE Senior Member > > Power Systems Researcher > -- Dr.-Ing. Santiago Torres IEEE Senior Member Power Systems Researcher
