Sir, Here i try to elaborate my question for your kind guidance I want to solve a non linear (AC Power Flow ) Problem using DC approximation (linear) method which gives estimations of lines power flows on AC power systems.It is non-iterative and absolutely convergent but less accurate than AC Load Flow (ACLF) solutions. DC approximation looks only at active power flows and neglects reactive power flows
I want to simplify the nonlinear model of the AC system to a linear form through these assumptions • Line resistances (active power losses) are negligible i.e. R<< X. • Voltage angle differences are assumed to be small i.e. sin(h) = h and cos(h) = 1. • Magnitudes of bus voltages are set to 1.0 per unit (flat voltage profile). • Tap settings are ignored. Regards Saeed Ahmed On 17 July 2017 at 23:41, Ray Zimmerman <[email protected]> wrote: > You can solve the DC power flow using rundcpf(). And MATPOWER does not > include a “WLS” function, so I’m not sure what you are referring to there. > > Ray > > > On Jul 17, 2017, at 9:34 AM, Saeed Ahmed <[email protected]> > wrote: > > > > Hi every one > > > > I need help for solving DC power flow using WLS function. I have tried > following and need guidance for developing it further. > > > > ************************************************************ > **************************************** > > cd = loadcase('case4gs'); > > casesystem = size(cd.bus, 1); > > cd.bus(:,6) = zeros(length(cd.bus(:,6)), 1) > > cd.branch((cd.branch(:,9) ~= 0),9) = zeros(size(cd.branch((cd.branch(:,9) > ~= 0),9))); > > pfres = runpf(cd); > > > > TCL MERGE ERROR ( 07/17/2017 10:41:24 ): "invalid command name > "Importing"" > OutmailID: 121661759, List: 'matpower-l', MemberID: 78104594 > SCRIPT: "Importing line Data > linedata = cd.branch(:, 1:6); % Calling > "linedata6.m" for Line Data... > linedata(:,6) = ones(size(linedata, 1),1); > > fb = linedata(:,1); % From bus number... > tb = linedata(:,2); % > To bus number... > r = linedata(:,3); % Resistance, R... > x = > linedata(:,4); % Reactance, X... > b = linedata(:,5)./2; % Ground > Admittance, B/2... > a = linedata(:,6); % Tap setting value.. %Assumed > 1 > > y = 1./(r + 1j*x); > > nbus = max(max(fb),max(tb)); % no. of > buses... > nbranch = length(fb); % no. of branches...¨ > >" > Formation of Y-Bus(Admittance) Matrix > > ybus = zeros(nbus,nbus); % Initialise YBus... > > % Formation of the Off-Diagonal Elements... > > for k=1:nbranch > > ybus(fb(k),tb(k)) = ybus(fb(k),tb(k))-y(k)/a(k); > > ybus(tb(k),fb(k)) = ybus(fb(k),tb(k)); > > end > > % Formation of Diagonal Elements... > > for m =1:nbus > > for n =1:nbranch > > if fb(n) == m > > ybus(m,m) = ybus(m,m) + y(n)/(a(n)^2) + 1j*b(n); > > elseif tb(n) == m > > ybus(m,m) = ybus(m,m) + y(n) + 1j*b(n); > > end > > end > > end > > ybus > > > > TCL MERGE ERROR ( 07/17/2017 10:41:24 ): "extra characters after > close-quote" > OutmailID: 121661759, List: 'matpower-l', MemberID: 78104594 > SCRIPT: "Formation of B-Bus > > Bp=-imag(ybus-diag(sum(ybus))); > > Bpp=imag(ybus) > ****************************** > ********************************************************************** > > > Regards > Saeed Ahmed > > --Apple-Mail=_7E621648-30BB-424D-B739-B09FEBED71AC > Content-Transfer-Encoding: quoted-printable Content-Type: text/html; > charset="utf-8" <html><head><meta http-equiv="Content-Type" > content="text/html charset=utf-8"></head><body style="word-wrap: > break-word; -webkit-nbsp-mode: space; -webkit-line-break: > after-white-space;" class="">You can solve the DC power flow using <font > face="Courier" class="">rundcpf()</font>. And MATPOWER does not include a > “WLS” function, so I’m not sure what you are referring to there.<div > class=""><div class=""><br class=""></div><div class=""> > Ray</div><div class=""><br class=""><div><blockquote type="cite" > class=""><div class="">On Jul 17, 2017, at 9:34 AM, Saeed Ahmed <<a > href="mailto:[email protected]"; class="">[email protected]</a>> > wrote:</div><br class="Apple-interchange-newline"><div class=""><div > dir="ltr" class=""><div class="gmail_default" style="font-family: tahoma, > sans-serif; font-size: small;">Hi every one </div><div > class="gmail_default" style="font-family: tahoma, sans-serif; font-size: > small;"><br class=""></div><div class="gmail_default" style="font-family: > tahoma, sans-serif; font-size: small;">I need help for solving DC power > flow using WLS function. I have tried following and need guidance for > developing it further.</div><div class="gmail_default" style="font-family: > tahoma, sans-serif; font-size: small;"><br class=""></div><div > class="gmail_default" style="font-family: tahoma, sans-serif; font-size: > small;">**************************************************** > ************************************************</div><div > class="gmail_default"><div class="gmail_default"><font face="tahoma, > sans-serif" class="">cd = loadcase('case4gs');</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class="">casesystem = > size(cd.bus, 1);</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class="">cd.bus(:,6) = zeros(length(cd.bus(:,6)), > 1)</font></div><div class="gmail_default"><font face="tahoma, sans-serif" > class="">cd.branch((cd.branch(:,9) ~= 0),9) = > zeros(size(cd.branch((cd.branch(:,9) > ~= 0),9)));</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class="">pfres = runpf(cd);</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class=""><br > class=""></font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class="">" > Importing line Data</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class="">linedata = cd.branch(:, 1:6); % Calling > "linedata6.m" for Line Data...</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class="">linedata(:,6) = ones(size(linedata, > 1),1);</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class="">fb = linedata(:,1); % From bus > number...</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class="">tb = linedata(:,2); % To bus > number...</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class="">r = linedata(:,3); % Resistance, > R...</font></div><div class="gmail_default"><font face="tahoma, sans-serif" > class="">x = linedata(:,4); % Reactance, > X...</font></div><div class="gmail_default"><font face="tahoma, sans-serif" > class="">b = linedata(:,5)./2; % Ground Admittance, > B/2...</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class="">a = linedata(:,6); % Tap setting > value.. %Assumed 1</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class=""><br class=""></font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class="">y = 1./(r + > 1j*x);</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class=""><br class=""></font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class="">nbus = > max(max(fb),max(tb)); % no. of buses...</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class="">nbranch = > length(fb); % no. of > branches...¨</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class=""><br class=""></font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class="">%% Formation > of Y-Bus(Admittance) Matrix</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class="">ybus = zeros(nbus,nbus); > % Initialise YBus... </font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class=""> % > Formation of the Off-Diagonal Elements...</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class=""> for > k=1:nbranch</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class=""> ybus(fb(k),tb(k)) = > ybus(fb(k),tb(k))-y(k)/a(k);</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class=""> ybus(tb(k),fb(k)) = > ybus(fb(k),tb(k));</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class=""> end</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class=""> % > Formation of Diagonal Elements...</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class=""> for m > =1:nbus</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class=""> for n =1:nbranch</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class=""> > if fb(n) == m</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class=""> > ybus(m,m) = ybus(m,m) + > y(n)/(a(n)^2) + 1j*b(n);</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class=""> elseif > tb(n) == m</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class=""> > ybus(m,m) = ybus(m,m) + y(n) + 1j*b(n);</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" class=""> > end</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class=""> end</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" > class=""> end</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class=""> ybus</font></div><div > class="gmail_default"><font face="tahoma, sans-serif" > class=""> </font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class=""> %% Formation of > B-Bus</font></div><div class="gmail_default"><font face="tahoma, > sans-serif" class=""> </font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class=""> Bp=-imag(ybus- > diag(sum(ybus)));</font></div><div class="gmail_default"><font > face="tahoma, sans-serif" class=""> Bpp=imag(ybus)</font></div></div><div > class="gmail_default" style="font-family: tahoma, sans-serif; font-size: > small;">**************************************************** > ************************************************<br class=""></div><div > class="gmail_default" style="font-family: tahoma, sans-serif; font-size: > small;"> </div><div class=""><div class="gmail_signature"><div > dir="ltr" class=""><div dir="ltr" class=""><div class=""><font face="arial > narrow, sans-serif" size="4" class="">Regards</font></div><div > class=""><font face="arial narrow, sans-serif" size="4" class="">Saeed > Ahmed</font></div><div class=""><br class=""></div></div></div></ > div></div> > </div> > </div></blockquote></div><br class=""></div></div></body></html>
