A method of calculating Available Transfer Capability and the exploration of the first order effects of certain power system network variables are described, The Federal Energy Regulatory Commission has ordered that bulk electrical control areas must provide to market participants a "commercially viable" network transfer capability for the import, export, and through-put of energy. A practical method for deriving this transfer capability utilizing both linear and non-linear power flow analysis methods is developed that acknowledges both thermal and voltage system limitations, The Available Transfer Capability is the incremental transfer capability derived by the method reduced by margins, A procedure for quantifying the first order effect of network uncertainties such as load forecast error and simultaneous transfers on the calculated transfer capability of a power system snapshot are explored. The quantification of these network uncertainties can provide information necessary for system operation, planning, and energy market participation.
