  In this letter we propose a generalized branch model to be used in DC optimal
power flow (DCOPF) applications. Besides AC lines and transformers, the
formulation allows for representing variable susceptance branches, phase
shifting transformers, HVDC lines, zero impedance lines and open branches. The
possibility to model branches with concurrently variable susceptance and
controllable phase shift angles is also provided. The model is suited for use
in DCOPF formulations aimed at the optimization of remedial actions so as to
exploit power system flexibility; applications to small-, medium- and
large-scale systems are presented to this purpose.
