Extended Enumeration of Hypothesized Substations Outages Incorporating Overload Implication

The risk of cascading outages is often associated with overloading. As a result of electrical short circuits, protective relaying picks up the faults and electrically disconnects overloaded transmission lines through circuit breakers. With similar disturbance and implication, disruptive switching cyberattacks in one or more compromised substations can initiate such events that will aggravate system’s operating conditions, leading to a widespread blackout. This paper proposes an extended enumeration of substation outages that excludes the overloaded lines from a power flow model. First, the exhaustive combination which starts from the initial combination size ${k=1}$ is enumerated searching for nonconvergent solutions of the hypothesized contingencies associated with the outages of single or more substations. The depth ${k=S'}$ is the level of contingencies which determines when the evaluation will halt. Each combination is then integrated with the overloaded effect that de-energizes transmission lines under the hypothesized scenarios. Nonconvergent solutions on both attack and overloading are carried to the next level of enumerations. This may include islanding that splits a system into multiple areas. The proposed power flow verification is validated using IEEE test cases as well as evaluation of parallel computing to determine its effectiveness of nonconvergent enumeration within a reasonable timeframe.