Tracing the flow of power in transmission networks for use-of-transmission-system charges and congestion management

With the separate pricing of generation and transmission, it has become necessary to find the capacity usage of different transactions occuring at the same time so that a fair use-of-transmission-system charge can be given separately to individual customers. It is also helpful to transmission congestion management if the power produced by each generator and consumed by each load could be tracked through the network, The existing proportional sharing and circuits based methods, and the newly developed power flow comparison method are introduced and compared in this paper. Calculations are illustrated in an example 6-bus power system. The new power flow comparison method and the existing proportional sharing method are also tested on the IEEE 57-bus system to show their capabilities. The power flow comparison method offers more alternatives in using available transmission capacity and pricing line flows, and provides the user with sensitivity information on how proposed corrections will affect the flows in other critical lines