5. Transient analysis with a classical generator model will be studied next for a three-phase

Question

bolted fault at bus 2. Assume the system is in its original state with bus 2 PD=720 MW,

QD=252 Mvar and PG3-520 MW before the new line was installed. Using the following

parameters for the GENCLS model,

G1: 400 MVA, H=1, D=1, Xd'=0.24

G3: 800 MVA, H=12, D=1, Xd'-0.24

determine the critical clearing angle, if any, that causes generator 1 to lose synchronism

with generator 3. Consider G3 with its large inertia to be similar to an infinite bus. Load

the DesignProject GENCLS auxiliary file using PowerWorld's Add Ons: Transient Stability

button near the top of the window. Note: you must be in "Run Mode" to select "Transient

Stability". Use the "Load All Settings From" button in the lower lefthand corner to open the

menu. Choose "Load Auxiliary..." and then select the proper AUX file. Modify the "Time

(Seconds)" field in the "Transient Contingency Elements" record in the lower panel to control

the time instant that the fault is cleared.

(a) Use the formulas given in lecture to determine the critical clearing angle for generator 1,

if any, using the internal power angle for generator 3 as a reference, similar to an infinite

bus.

(b) Use PowerWorld to determine the clearing angle that causes generator 1 to hit the

highest angle it can without losing synchronism with generator 3. When you find the

largest clearing angle, capture the generator power angle plot (not the rotor angle plot)

by first clicking on the small triangle in the lower righthand corner of the plot window,

and then selecting the "Export Chart..." option.

(c) Compare the results from your formula-based calculation and the PowerWorld simula-

tion.