Stochastic-Algebraic Calculation of Available Transfer Capability

Power systems are stochastic in nature due to uncertainty in bus loading and transmission system asset status. The available transfer capability (ATC) is a measure of "available capacity" in a power transmission system beyond already committed uses, i.e., beyond base case loading. To render the ATC as a more realistic measure of transmission availability, a stochastic calculation of ATC is proposed. A stochastic power flow algorithm can be used to help quantify and evaluate the uncertainty of the ATC. The limitations considered in the stochastic ATC calculation algorithm are: transmission thermal rating limits; bus voltage magnitude limits; and transmission circuit outages. The stochastic-algebraic calculation of ATC is described and tested using a reduced order WECC 179 bus system