MAKEYBUS Builds the bus admittance matrix and branch admittance matrices. [YBUS, YF, YT] = MAKEYBUS(MPC) [YBUS, YF, YT] = MAKEYBUS(BASEMVA, BUS, BRANCH) Returns the full bus admittance matrix (i.e. for all buses) and the matrices YF and YT which, when multiplied by a complex voltage vector, yield the vector currents injected into each line from the "from" and "to" buses respectively of each line. Does appropriate conversions to p.u. Inputs can be a MATPOWER case struct or individual BASEMVA, BUS and BRANCH values. Bus numbers must be consecutive beginning at 1 (internal ordering). See also MAKEJAC, MAKESBUS, EXT2INT.
0001 function [Ybus, Yf, Yt] = makeYbus(baseMVA, bus, branch) 0002 %MAKEYBUS Builds the bus admittance matrix and branch admittance matrices. 0003 % [YBUS, YF, YT] = MAKEYBUS(MPC) 0004 % [YBUS, YF, YT] = MAKEYBUS(BASEMVA, BUS, BRANCH) 0005 % 0006 % Returns the full bus admittance matrix (i.e. for all buses) and the 0007 % matrices YF and YT which, when multiplied by a complex voltage vector, 0008 % yield the vector currents injected into each line from the "from" and 0009 % "to" buses respectively of each line. Does appropriate conversions to p.u. 0010 % Inputs can be a MATPOWER case struct or individual BASEMVA, BUS and 0011 % BRANCH values. Bus numbers must be consecutive beginning at 1 (internal 0012 % ordering). 0013 % 0014 % See also MAKEJAC, MAKESBUS, EXT2INT. 0015 0016 % MATPOWER 0017 % $Id: makeYbus.m,v 1.17 2010/06/25 17:37:40 ray Exp $ 0018 % by Ray Zimmerman, PSERC Cornell 0019 % Copyright (c) 1996-2010 by Power System Engineering Research Center (PSERC) 0020 % 0021 % This file is part of MATPOWER. 0022 % See http://www.pserc.cornell.edu/matpower/ for more info. 0023 % 0024 % MATPOWER is free software: you can redistribute it and/or modify 0025 % it under the terms of the GNU General Public License as published 0026 % by the Free Software Foundation, either version 3 of the License, 0027 % or (at your option) any later version. 0028 % 0029 % MATPOWER is distributed in the hope that it will be useful, 0030 % but WITHOUT ANY WARRANTY; without even the implied warranty of 0031 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 0032 % GNU General Public License for more details. 0033 % 0034 % You should have received a copy of the GNU General Public License 0035 % along with MATPOWER. If not, see <http://www.gnu.org/licenses/>. 0036 % 0037 % Additional permission under GNU GPL version 3 section 7 0038 % 0039 % If you modify MATPOWER, or any covered work, to interface with 0040 % other modules (such as MATLAB code and MEX-files) available in a 0041 % MATLAB(R) or comparable environment containing parts covered 0042 % under other licensing terms, the licensors of MATPOWER grant 0043 % you additional permission to convey the resulting work. 0044 0045 if nargin < 3 0046 mpc = baseMVA; 0047 baseMVA = mpc.baseMVA; 0048 bus = mpc.bus; 0049 branch = mpc.branch; 0050 end 0051 0052 %% constants 0053 nb = size(bus, 1); %% number of buses 0054 nl = size(branch, 1); %% number of lines 0055 0056 %% define named indices into bus, branch matrices 0057 [PQ, PV, REF, NONE, BUS_I, BUS_TYPE, PD, QD, GS, BS, BUS_AREA, VM, ... 0058 VA, BASE_KV, ZONE, VMAX, VMIN, LAM_P, LAM_Q, MU_VMAX, MU_VMIN] = idx_bus; 0059 [F_BUS, T_BUS, BR_R, BR_X, BR_B, RATE_A, RATE_B, RATE_C, ... 0060 TAP, SHIFT, BR_STATUS, PF, QF, PT, QT, MU_SF, MU_ST, ... 0061 ANGMIN, ANGMAX, MU_ANGMIN, MU_ANGMAX] = idx_brch; 0062 0063 %% check that bus numbers are equal to indices to bus (one set of bus numbers) 0064 if any(bus(:, BUS_I) ~= (1:nb)') 0065 error('buses must appear in order by bus number') 0066 end 0067 0068 %% for each branch, compute the elements of the branch admittance matrix where 0069 %% 0070 %% | If | | Yff Yft | | Vf | 0071 %% | | = | | * | | 0072 %% | It | | Ytf Ytt | | Vt | 0073 %% 0074 stat = branch(:, BR_STATUS); %% ones at in-service branches 0075 Ys = stat ./ (branch(:, BR_R) + 1j * branch(:, BR_X)); %% series admittance 0076 Bc = stat .* branch(:, BR_B); %% line charging susceptance 0077 tap = ones(nl, 1); %% default tap ratio = 1 0078 i = find(branch(:, TAP)); %% indices of non-zero tap ratios 0079 tap(i) = branch(i, TAP); %% assign non-zero tap ratios 0080 tap = tap .* exp(1j*pi/180 * branch(:, SHIFT)); %% add phase shifters 0081 Ytt = Ys + 1j*Bc/2; 0082 Yff = Ytt ./ (tap .* conj(tap)); 0083 Yft = - Ys ./ conj(tap); 0084 Ytf = - Ys ./ tap; 0085 0086 %% compute shunt admittance 0087 %% if Psh is the real power consumed by the shunt at V = 1.0 p.u. 0088 %% and Qsh is the reactive power injected by the shunt at V = 1.0 p.u. 0089 %% then Psh - j Qsh = V * conj(Ysh * V) = conj(Ysh) = Gs - j Bs, 0090 %% i.e. Ysh = Psh + j Qsh, so ... 0091 Ysh = (bus(:, GS) + 1j * bus(:, BS)) / baseMVA; %% vector of shunt admittances 0092 0093 %% build connection matrices 0094 f = branch(:, F_BUS); %% list of "from" buses 0095 t = branch(:, T_BUS); %% list of "to" buses 0096 Cf = sparse(1:nl, f, ones(nl, 1), nl, nb); %% connection matrix for line & from buses 0097 Ct = sparse(1:nl, t, ones(nl, 1), nl, nb); %% connection matrix for line & to buses 0098 0099 %% build Yf and Yt such that Yf * V is the vector of complex branch currents injected 0100 %% at each branch's "from" bus, and Yt is the same for the "to" bus end 0101 i = [1:nl; 1:nl]'; %% double set of row indices 0102 Yf = sparse(i, [f; t], [Yff; Yft], nl, nb); 0103 Yt = sparse(i, [f; t], [Ytf; Ytt], nl, nb); 0104 % Yf = spdiags(Yff, 0, nl, nl) * Cf + spdiags(Yft, 0, nl, nl) * Ct; 0105 % Yt = spdiags(Ytf, 0, nl, nl) * Cf + spdiags(Ytt, 0, nl, nl) * Ct; 0106 0107 %% build Ybus 0108 Ybus = Cf' * Yf + Ct' * Yt + ... %% branch admittances 0109 sparse(1:nb, 1:nb, Ysh, nb, nb); %% shunt admittance