Transmission capacity assessment

The problem of electric power transmission limitations due to finite reactive resources is studied. Maximum system load, i.e., loadability, is determined using a nonlinear optimization technique (Modified Augmented Lagrangian) which accommodates limits on reactive generation as well as other practical constraints. The sensitivities of the system loadability with regard to transmission-element primitive admittances are by-products of the proposed optimization method. These parameters indicate the relative strength of the transmission elements at the voltage stability limit. The weakest element is considered to be the one exhibiting the greatest sensitivity. Electrical strengthening of this element would enhance the system loadability. Sample results are presented for a 30-bus system.