  Phase Shifting Transformers (PST) are used to control or block certain flows
of real power through phase angle regulation across the device. Its
functionality is crucial to special situations such as eliminating loop flow
through an area and balancing real power flow between parallel paths. Impedance
correction tables are used to model that the impedance of phase shifting
transformers often vary as a function of their phase angle shift. The focus of
this paper is to consider the modeling errors if the impact of this changing
impedance is ignored. The simulations are tested through different scenarios
using a 37-bus test case and a 10,000-bus synthetic power grid. The results
verify the important role of impedance correction factor to get more accurate
and optimal power solutions.
