Identification of Critical Cutsets for Static Collapse Analysis

This paper deals with static transfer stability limits (STSLs) of network branches, cutsets of network branches, and their relation to power flow Jacobian singularity. A minimal cutset is a grouping of system branches that -if removed from the system -separates the seller and buyer for a given transaction into two separate subsystems (islands) of the original network while containing no unnecessary branches in the grouping. Originally, it was proposed to define a critical cutset as a minimal cutset of system branches that exactly reaches its own cutset STSL (CSTSL) at the instant of power flow Jacobian singularity. However, it is shown that line inductive losses can reveal more information. A critical cutset is defined as the transfer loss stability limit (Critical Cut TLSL) as the point of system collapse. This paper proposes a conjecture that at least one minimal cutset in a power system is the critical cutset for a given transfer. Multiple power system models are analyzed to experimentally support the conjecture.