Dear Wu Jun, I do not believe that the approach you propose will work because the power-flow equations (normally) do not include the machine reactance. As you know, when calculating the short-circuit impedance at a network node, synchronous machines should be represented by a constant-voltage behind an appropriate impedance. The appropriate impedance might typically be the sub-transient reactance or transient reactance of the machine, depending on the time-frame of interest. In the loadflow computation, (typically) the generator terminal voltage is constant, which represents the longer-term response of the machine due to the action of the automatic voltage regulator (AVR).
Hope this helps, David. Wu Jun wrote: > Ara and others, > > I think the short circuit currents (3-phase SC) can be easily calculated by > the practical formula shown as below, isn’t it? > Id=V(0)/Zdd > where Id is the short circuit current (3-phase SC), V(0) is the initial > voltage at the failure point and Zdd is the self-reactance of the failure > point. > So I think Matpower can also calculate it because all elements in the right > side of the formula can be achieved in the process of calculating the power > flow. But I am not familiar with the inner structure of Matpower. > I am wondering how to get the Zdd from it? > > -------------- > Yours sincerely, > Wu Jun > Unit: State Key Lab. of Power Systems, > Dep. of Electrical Engineering, > Tsinghua University, P.R. China. > Email: [email protected] > 2007-04-18 > > > > 发件人： Panosyan, Ara > 发送时间： 2007-04-13 20:21:58 > 收件人： [email protected] > 抄送： > 主题： [?? Probable Spam] WG: Re: About the short circuit current > > > Wu, > > as I wrote in my first email, I am not sure what each tool can, since I > haven't used any of them, but I thought maybe you would be interested in > knowing about the available Matlab Tools for PS-Analysis. > > I am not sure what kind of analysis do you mean? Do you want to calculate > only the short circuit currents (3-phase SC)? Or the dynamic fault analysis? > I guess if it’s the 2nd one, then you should be able to use many tools. Short > circuit current calculation according to standard procedure (i.e. IEC 909 or > ANSI http://ieeexplore.ieee.org/iel1/28/5799/00222435.pdf?arnumber=222435) is > probably a bit trickier to program, because of its unsystematic nature. Maybe > that’s why most tools still don't have it. > > Regards > > Ara > > > ------------------------------------ > Dipl.-Ing. Ara Panosyan > University of Hannover > Institute of Electric Power Systems > [email protected] > ------------------------------------ > > > -----Ursprüngliche Nachricht----- > Von: [email protected] > [mailto:[email protected]] Im Auftrag von ?? > Gesendet: Freitag, 13. April 2007 10:44 > An: MATPOWER discussion forum > Betreff: Re: [?? Probable Spam] Re: About the short circuit current > > Ara, > > Thanks for your attention and suggestion. > I've read the paper and gotten more information about the PSAT from the > author's homepage. But unfortunately, the author said below words in one > presentation: The fault analysis and some other tools are still not available > as Matlab packages or toolboxes. So I have to go on looking for other tools. > > -------------- > Yours sincerely, > Wu Jun > Unit: State Key Lab. of Power Systems, > Dep. of Electrical Engineering, > Tsinghua University, P.R. China. > Email: [email protected] > 2007-04-13 > > > > 发件人： Panosyan, Ara > 发送时间： 2007-04-12 21:09:08 > 收件人： MATPOWER discussion forum > 抄送： > 主题： [?? Probable Spam] Re: About the short circuit current > > Wu, > > check this paper for some of the available Matlab based PS-Tools. > But it doesn't look like any of them has the IEC-standard short-circuit > calculation (if that is what you are looking for?). > I'm not sure thought, since I haven't used any of them. > > http://www.power.uwaterloo.ca/~claudio/courses/ece664/project/PSATpaper.pdf > > Ara > > ------------------------------------ > Dipl.-Ing. Ara Panosyan > University of Hannover > Institute of Electric Power Systems > [email protected] > ------------------------------------ > > > -----Urspr�ngliche Nachricht----- > Von: [email protected] > [mailto:[email protected]] Im Auftrag von ?? > Gesendet: Donnerstag, 12. April 2007 14:31 > An: matpower-l > Betreff: About the short circuit current > > Hi all, > > Can the Matpower calculate the short circuit currents? > If it can not, which one can? Please introduce one toolbox in MATLAB for me. > Thanks! > > > -------------- > Yours sincerely, > Wu Jun > 2007-04-12 > -- David Vowles, Research Engineer, School of Electrical and Electronic Engineering, The University of Adelaide, Australia, 5005. Phone: +61 8 8303 5416 Fax: +61 8 8303 4360
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