  Phasor Measurement Unit measurement data have been widely used in nowadays
power system applications both in steady state and dynamic analysis. The
performance of these applications running in utilities' energy management
system depends heavily on an accurate positive sequence power system model.
However, it is impractical to find this accurate model with transmission line
parameters calculated directly with the PMU measurements due to ratio errors
brought by instrument transformers and communication errors brought by PMUs.
Therefore, a methodology is proposed in this paper to estimate the actual
transmission lines parameters throughout the whole system and, at the same
time, calibrate the corresponding instrument transformers. A PMU positive
sequence measurement error model is proposed targeting at the aforementioned
errors, which is applicable to both transposed and un-transposed transmission
lines. A single line parameters estimation method is designed based on Least
Squares Estimation and this error model. This method requires only one set of
reference measurements and the accuracy can be propagated throughout the whole
network along with the topology acquired by the introduced Edge-based
Breadth-first Search algorithm. The IEEE 118-bus system and the Texas 2000-bus
system are used to demonstrate the effectiveness and efficiency of the proposed
method. The potential for deployment in reality is also discussed.
