function [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%IDX_BUS   Defines constants for named column indices to bus matrix.%   [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%%   Some examples of usage, after defining the constants using the line above,%   are:%%    Pd = bus(4, PD);       % get the real power demand at bus 4%    bus(:, VMIN) = 0.95;   % set the min voltage magnitude to 0.95 at all buses% %   The index, name and meaning of each column of the bus matrix is given%   below:%%   columns 1-13 must be included in input matrix (in case file)%    1  BUS_I       bus number (1 to 29997)%    2  BUS_TYPE    bus type (1 = PQ, 2 = PV, 3 = ref, 4 = isolated)%    3  PD          Pd, real power demand (MW)%    4  QD          Qd, reactive power demand (MVAr)%    5  GS          Gs, shunt conductance (MW at V = 1.0 p.u.)%    6  BS          Bs, shunt susceptance (MVAr at V = 1.0 p.u.)%    7  BUS_AREA    area number, 1-100%    8  VM          Vm, voltage magnitude (p.u.)%    9  VA          Va, voltage angle (degrees)%    10 BASE_KV     baseKV, base voltage (kV)%    11 ZONE        zone, loss zone (1-999)%    12 VMAX        maxVm, maximum voltage magnitude (p.u.)%    13 VMIN        minVm, minimum voltage magnitude (p.u.)%   %   columns 14-17 are added to matrix after OPF solution%   they are typically not present in the input matrix%                   (assume OPF objective function has units, u)%    14 LAM_P       Lagrange multiplier on real power mismatch (u/MW)%    15 LAM_Q       Lagrange multiplier on reactive power mismatch (u/MVAr)%    16 MU_VMAX     Kuhn-Tucker multiplier on upper voltage limit (u/p.u.)%    17 MU_VMIN     Kuhn-Tucker multiplier on lower voltage limit (u/p.u.)% %   additional constants, used to assign/compare values in the BUS_TYPE column%    1  PQ    PQ bus%    2  PV    PV bus%    3  REF   reference bus%    4  NONE  isolated bus%   MATPOWER%   $Id: idx_bus.m,v 1.5 2004/12/15 22:46:28 ray Exp $%   by Ray Zimmerman, PSERC Cornell%   Copyright (c) 1996-2004 by Power System Engineering Research Center (PSERC)%   See http://www.pserc.cornell.edu/matpower/ for more info.%% define bus typesPQ      = 1;PV      = 2;REF     = 3;NONE    = 4;%% define the indicesBUS_I       = 1;    %% bus number (1 to 29997)BUS_TYPE    = 2;    %% bus type (1 - PQ bus, 2 - PV bus, 3 - reference bus, 4 - isolated bus)PD          = 3;    %% Pd, real power demand (MW)QD          = 4;    %% Qd, reactive power demand (MVAr)GS          = 5;    %% Gs, shunt conductance (MW at V = 1.0 p.u.)BS          = 6;    %% Bs, shunt susceptance (MVAr at V = 1.0 p.u.)BUS_AREA    = 7;    %% area number, 1-100VM          = 8;    %% Vm, voltage magnitude (p.u.)VA          = 9;    %% Va, voltage angle (degrees)BASE_KV     = 10;   %% baseKV, base voltage (kV)ZONE        = 11;   %% zone, loss zone (1-999)VMAX        = 12;   %% maxVm, maximum voltage magnitude (p.u.)      (not in PTI format)VMIN        = 13;   %% minVm, minimum voltage magnitude (p.u.)      (not in PTI format)%% included in opf solution, not necessarily in input%% assume objective function has units, uLAM_P       = 14;   %% Lagrange multiplier on real power mismatch (u/MW)LAM_Q       = 15;   %% Lagrange multiplier on reactive power mismatch (u/MVAr)MU_VMAX     = 16;   %% Kuhn-Tucker multiplier on upper voltage limit (u/p.u.)MU_VMIN     = 17;   %% Kuhn-Tucker multiplier on lower voltage limit (u/p.u.)return;