//IDX_BUS   Defines constants for named column indices to bus matrix.
//   Example:
//
//   [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 (positive integer)
//    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 demanded at V = 1.0 p.u.)
//    6  BS          Bs, shunt susceptance (MVAr injected at V = 1.0 p.u.)
//    7  BUS_AREA    area number, (positive integer)
//    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 (positive integer)
//    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
//
//   See also DEFINE_CONSTANTS.

//   MATPOWER
//   Copyright (c) 1996-2016, Power Systems Engineering Research Center (PSERC)
//   by Ray Zimmerman, PSERC Cornell
//
//   This file is part of MATPOWER.
//   Covered by the 3-clause BSD License (see LICENSE file for details).
//   See https://matpower.org for more info.

// define bus types
PQ      = 1;
PV      = 2;
REF     = 3;
NONE    = 4;

// define the indices
BUS_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, 1-100
VM          = 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, u
LAM_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.)
