  Transmission networks consist of thousands of branches for large-scale real
power systems. They are built with a high degree of redundancy for reliability
concern. Thus, it is very likely that there exist various network topologies
that can deliver continuous power supply to consumers. The optimal transmission
network topology could be very different for different system conditions.
Transmission network topology control (TNTC) can provide the operator with an
additional option to manage network congestion, reduce losses, relieve
violation, and achieve cost saving. This paper examines the benefits of TNTC in
reducing post-contingency overloads that are identified by real-time
contingency analysis (RTCA). The procedure of RTCA with TNTC is presented and
two algorithms are proposed to determine the candidate switching solutions.
Both algorithms use available system data: sensitivity factors or shifting
factors. The proposed two TNTC approaches are based on the transmission
switching distribution factor (TSDF) and flow transfer distribution factor
(FTDF) respectively. FTDF based TNTC approach is an enhanced version of TSDF
based TNTC approach by considering network flow distribution. Numerical
simulations demonstrate that both methods can effectively relieve flow
violations and FTDF outperforms TSDF.
