Real-Time Estimation of Transmission Losses from PMU Measurements

This paper discusses the application of PMU measurements in real-time estimation of transmission line power losses. Instead of directly computing the difference between sent and received power, the losses are estimated as separate components, calculated from line equations. On one hand, this provides more information about the operation of the line-active losses are split into Joule and corona losses and the balance of reactive power is separated into inductive losses and capacitive generation. On the other hand, it reveals large measurement errors in active losses on lightly loaded transmission lines, closely related to similar errors in estimated line parameters. This is demonstrated on examples of actual PMU measurements of a transmission line at low loads.