,, and are complex voltages and currents at “from” and “to” ends of the branch. The series controllable parameters, and are used to describe the effects of TCSC, TCPS and ULTC, respectively. Shunt compensation devices can be modelled as extra susceptance at their buses so that they are not shown in Fig. 1.
,
, 
and 
are complex voltages and currents at “from” and “to” ends of the branch. The 
, 
and 
are used to 