How i can do dynamic simulation and find Critical Clearing Time in PSS/E?

dsam
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Hello, When I do dynamic simulation in PSS/E to find the critical clearing time I notice from channels plot that if a fault occurs in a bus with generator the network is asynchronous at any time I clear the fault and a line is tripped. On the contrary, when an fault occurs in any other bus, the system is permanently synchronized at any time I clear the fault. So i can not find the critical clearing time. Can someone explain to me why this is happening and what I am doing wrong?

answered May 19 '1

perolofl

3452 ●1 ●9 ●20

updated May 19 '1

Maybe you are isolating the generator bus from the rest of the system when you trip a line (or transformer?) at fault clearing? Or you are splitting the system into two separate systems?

EDIT: Maybe you are not doing anything wrong. It is a small test system and it might be that all generators are accelerating similarly for some fault locations and synchronism is maintained even for long fault clearing times. Plot the speed deviation for all generators and see if they are following each other.

link

Comments

The network I use is ieee 14 bus. When I trip a line at fault clearing, there is another line that connects this bus with the rest of the network.

dsam (May 19 '1)

I plotted the speed deviation for all generators and i noticed that they are not following each other when the fault occurs in a generator bus and the network is asynchronous.

dsam (May 19 '1)

Exactly, this shows that there are fault locations where no generator will go out of step. It is best seen in the rotor angles but also in speed. Nothing is wrong with the results.