Modelling of transformers in PSS/E

Figure 1 represents the internal PSS/E model for the two winding transformer model

and Figure 2 resents its approximated transformer model. In this model Z represents the

series impedance and Ym represents the magnetizing admittance [1],[2].

Figure 1: PSS/E Transformer models of two winding transformer model

Figure 2: Standard PSS/E two winding Transformer circuit

Modelling of two winding transformers in PSS/E requires following minimum

parameters. They are,

Winding 1& 2 ratio (pu) = 1pu:1pu ratio was set in the model.

Winding 1&2 Nominal Voltage (kV) = Respective voltages of the buses was entered in the

model.

Winding MVA = 100MVA which is the default power base was set.

Rate A (MVA) = Transformer capacity.

Rate B (MVA) = The contingency rating is set 120% of the Rate A.

Series Resistance R (pu) = assumed to be negligible.

Series Reactance X (pu) = Since the series resistance was assumed to be negligible, reactance

(X) was assumed to be equal to the percentage impedance (Z).

Shunt Conductance G (pu) = Assumed to be negligible.

Shunt Susceptance B (pu) = Assumed to be negligible.

References

[1] “PSS®E 33.2 Program Operation Manual.” Siemens Industry, Inc. Siemens Power

Technologies International.

[2] “Transformers in the positive sequence,” in Program Application Guide, vol. 1, 2 vols.,

SEIMENS.