Increasing the Effectiveness of Interface MW Limits for Maintaining Voltage Security

Interface MW limits are commonly used as surrogates for voltage constraints in DC power flow models. This work proposes a simple improvement to accepted practice so that the interface MW limits better represent actual voltage vulnerability. Weights are assigned to the individual lines in the interface so that the weighted interface MW flows have the same sensitivity to real power injections as the underlying voltage constraints. Calculation of the weights requires the solution of a small dimensional linear regression equation and is of slight computational burden. The weighted interface MW limit is demonstrated to be an accurate proxy for low voltage limits to inter-area transfers using the Nordic test system.