This paper investigates the effects of measurement and parameter
errors on the calculation of power transfer distribution factors (PTDFs).
Calculation of PTDFs depends mainly on two factors: the operating
conditions and the network topology. Both of these factors change in real
time and are monitored through the use of a state estimator. The role of
the state estimator in providing not only the state information but also
the real-time network model is shown to influence power market operations
via PTDF-based decisions such as congestion management and pricing. The
IEEE 14 bus test system is used for the illustration of these
influences.