Available transfer capability applying linear phasor methods to the AC power flow

Abstract

The DC Load Flow is a fast tool to aid in calculating transfer capabilities in large power system models, such as the MMWG eastern interconnection. Unfortunately, it has numerous short comings that might best be summed up by noting that when the BES is the most stressed, the DC Load Flow is the least accurate. Low voltages, high loss situations, bad X/R ratios etc., are detractors for the accuracy of the DC Load Flow, just when the planners are seeking the best answers they can get to maintain system security. The authors propose some simple methods to borrow linear theory and apply these techniques to simplify AC transfer analysis. Reversing the concept that the DC Load Flow is an accurate representation of the “non-linear” AC power flow, we find that the AC power flow is locally linear in the phasor domain and thus, linear methods can be used effectively for ATC calculations. This paper shows how NITC and FCITC can be calculated using a simple Phasor Method, which gains us ATC results from the more robust AC power flow model.