total_load

total_load(bus, gen, load_zone, opt, mpopt)
total_load() - Returns vector of total load in each load zone.
PD = TOTAL_LOAD(MPC)
PD = TOTAL_LOAD(MPC, LOAD_ZONE)
PD = TOTAL_LOAD(MPC, LOAD_ZONE, OPT)
PD = TOTAL_LOAD(MPC, LOAD_ZONE, OPT, MPOPT)
PD = TOTAL_LOAD(BUS)
PD = TOTAL_LOAD(BUS, GEN)
PD = TOTAL_LOAD(BUS, GEN, LOAD_ZONE)
PD = TOTAL_LOAD(BUS, GEN, LOAD_ZONE, OPT)
PD = TOTAL_LOAD(BUS, GEN, LOAD_ZONE, OPT, MPOPT)
[PD, QD] = TOTAL_LOAD(...) returns both active and reative power
demand for each zone.

MPC - standard MATPOWER case struct

BUS - standard BUS matrix with nb rows, where the fixed active
    and reactive loads are specified in columns PD and QD

GEN - (optional) standard GEN matrix with ng rows, where the
    dispatchable loads are specified by columns PG, QG, PMIN,
    QMIN and QMAX (in rows for which ISLOAD(GEN) returns true).
    If GEN is empty, it assumes there are no dispatchable loads.

LOAD_ZONE - (optional) nb element vector where the value of
    each element is either zero or the index of the load zone
    to which the corresponding bus belongs. If LOAD_ZONE(b) = k
    then the loads at bus b will added to the values of PD(k) and
    QD(k). If LOAD_ZONE is empty, the default is defined as the areas
    specified in the BUS matrix, i.e. LOAD_ZONE = BUS(:, BUS_AREA)
    and load will have dimension = MAX(BUS(:, BUS_AREA)). LOAD_ZONE
    can also take the following string values:
        'all'  - use a single zone for the entire system (return scalar)
        'area' - use LOAD_ZONE = BUS(:, BUS_AREA), same as default
        'bus'  - use a different zone for each bus (i.e. to compute
            final values of bus-wise loads, including voltage dependent
            fixed loads and or dispatchable loads)

OPT - (optional) option struct, with the following fields:
        'type'  -  string specifying types of loads to include, default
                   is 'BOTH' if GEN is provided, otherwise 'FIXED'
            'FIXED'        : sum only fixed loads
            'DISPATCHABLE' : sum only dispatchable loads
            'BOTH'         : sum both fixed and dispatchable loads
        'nominal' -  1 : use nominal load for dispatchable loads
                     0 : (default) use actual realized load for
                          dispatchable loads

    For backward compatibility with MATPOWER 4.x, OPT can also
    take the form of a string, with the same options as OPT.type above.
    In this case, again for backward compatibility, it is the "nominal"
    load that is computed for dispatchable loads, not the actual
    realized load. Using a string for OPT is deprecated and
    will be removed in a future version.

MPOPT - (optional) MATPOWER options struct, which may specify
    a voltage dependent (ZIP) load model for fixed loads

Examples:
    Return the total active load for each area as defined in BUS_AREA.

    Pd = total_load(bus);

    Return total active and reactive load, fixed and dispatchable, for
    entire system.

    [Pd, Qd] = total_load(bus, gen, 'all');

    Return the total of the nominal dispatchable loads at buses 10-20.

    load_zone = zeros(nb, 1);
    load_zone(10:20) = 1;
    opt = struct('type', 'DISPATCHABLE', 'nominal', 1);
    Pd = total_load(mpc, load_zone, opt)