, the load is
Constant power loads are modeled as a specified quantity of real and reactive power
consumed at a bus. For bus , the load is
 | (3.6) |
and 
denotes the 
vector of complex loads at all buses. The MW
and MVAr equivalents (before conversion to p.u.) of 
and 
are specified
in columns PD (3) and QD (4), respectively of row 
of the bus matrix. These
fields can also take on negative quantities to represent fixed (e.g. distributed)
generation.
Constant impedance and constant current loads are not implemented directly, but the
constant impedance portions can be modeled as a shunt element described below.
Dispatchable loads are modeled as negative generators and appear as negative values in
.