OPTIMAL POWER FLOW PROBLEM FORMULATION
Generally, the OPF problem can be
formulated as follows [1]:
(1)
Subject to:
(2)
(3)
(4)
where J is objective function to be minimized. x is the
vector of dependent variables consisting of slack bus powerPG 1, load bus voltagesVL , generator reactive power outputsQG , and transmission line loadingsSl . Accordingly, vector x can be
expressed as:
(5)
where NL, NG and NTL are number of load buses, number of generators, and
number of transmission lines, respectively.
u is the vector of control variables, consisting of generator
active power outputs PG (except at the slack busPG 1), generator voltagesVG , transformer tap settings T , and shunt
VAR compensations QC . Hence, u can be
expressed as:
(6)
where NT and NC are the number of the regulating transformer and VAR
compensators, respectively.