gusucode.com > matpower工具箱源码程序 > matpower工具箱源码程序/MP2_0/makeYbus.m
function [Ybus, Yf, Yt] = makeYbus(baseMVA, bus, branch) %MAKEYBUS Builds the bus admittance matrix and branch admittance matrices. % [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. % MATPOWER Version 2.0 % by Ray Zimmerman, PSERC Cornell 12/19/97 % Copyright (c) 1996, 1997 by Power System Engineering Research Center (PSERC) % See http://www.pserc.cornell.edu/ for more info. %% constants j = sqrt(-1); nb = size(bus, 1); %% number of buses nl = size(branch, 1); %% number of lines %% define named indices into bus, branch matrices [PQ, PV, REF, NONE, BUS_I, BUS_TYPE, PD, QD, GS, BS, BUS_AREA, VM, ... VA, BASE_KV, ZONE, VMAX, VMIN, LAM_P, LAM_Q, MU_VMAX, MU_VMIN] = idx_bus; [F_BUS, T_BUS, BR_R, BR_X, BR_B, RATE_A, RATE_B, ... RATE_C, TAP, SHIFT, BR_STATUS, PF, QF, PT, QT, MU_SF, MU_ST] = idx_brch; %% check that bus numbers are equal to indices to bus (one set of bus numbers) if any(bus(:, BUS_I) ~= [1:nb]') error('buses must appear in order by bus number') end %% for each branch, compute the elements of the branch admittance matrix where %% %% | If | | Yff Yft | | Vf |; %% | | = | | * | |; %% | It | | Ytf Ytt | | Vt |; %% stat = branch(:, BR_STATUS); %% ones at in-service branches Ys = stat ./ (branch(:, BR_R) + j * branch(:, BR_X)); %% series admittance Bc = stat .* branch(:, BR_B); %% line charging susceptance tap = ones(nl, 1); %% default tap ratio = 1 i = find(branch(:, TAP)); %% indices of non-zero tap ratios tap(i) = branch(i, TAP); %% assign non-zero tap ratios tap = tap .* exp(j*pi/180 * branch(:, SHIFT)); %% add phase shifters Ytt = Ys + j*Bc/2; Yff = Ytt ./ (tap .* conj(tap)); Yft = - Ys ./ conj(tap); Ytf = - Ys ./ tap; %% compute shunt admittance %% if Ps is the real power consumed by the shunt at V = 1.0 p.u. %% and Qs is the reactive power injected by the shunt at V = 1.0 p.u. %% then Ps - j Qs = V * conj(Ys * V) = conj(Ys) = Gs - j Bs, %% i.e. Ys = Ps + j Qs, so ... Ys = (bus(:, GS) + j * bus(:, BS)) / baseMVA; %% vector of shunt admittances %% build Ybus f = branch(:, F_BUS); %% list of "from" buses t = branch(:, T_BUS); %% list of "to" buses Cf = sparse(f, 1:nl, ones(nl, 1), nb, nl); %% connection matrix for line & from buses Ct = sparse(t, 1:nl, ones(nl, 1), nb, nl); %% connection matrix for line & to buses Ybus = spdiags(Ys, 0, nb, nb) + ... %% shunt admittance Cf * spdiags(Yff, 0, nl, nl) * Cf' + ... %% Yff term of branch admittance Cf * spdiags(Yft, 0, nl, nl) * Ct' + ... %% Yft term of branch admittance Ct * spdiags(Ytf, 0, nl, nl) * Cf' + ... %% Ytf term of branch admittance Ct * spdiags(Ytt, 0, nl, nl) * Ct'; %% Ytt term of branch admittance %% Build Yf and Yt such that Yf * V is the vector of complex branch currents injected %% at each branch's "from" bus, and Yt is the same for the "to" bus end if nargout > 1 i = [[1:nl]'; [1:nl]']; %% double set of row indices Yf = sparse(i, [f; t], [Yff; Yft]); Yt = sparse(i, [f; t], [Ytf; Ytt]); end return;