  Accurate grid topology information is of paramount importance for routine
power system operations, while the growing availability of synchrophasor data
offers the opportunity to identify topology changes in real time.
Identification of bus split events, where the substation becomes electrically
disconnected, is becoming increasingly important for maintaining the security
of power systems. This paper aims to provide an efficient modeling and
monitoring framework for bus split events by using a concise bus-branch
representation. The linear sensitivity analysis is first performed to quickly
evaluate the grid-wide impact of such events. Furthermore, the synchrophasor
data enabled identification problem is formulated by matching the changes in
bus phase angles (and possibly line flows). To address the resultant bilinear
multiplication involving the binary connectivity variables, the McCormick
relaxation technique is leveraged to attain an equivalent mixed-integer linear
program reformulation that is efficiently solvable. Numerical studies on the
IEEE 14-bus and 300-bus systems demonstrate the validity and efficiency of the
proposed identification algorithm towards real-time implementation.
