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PSS/E vs E-tran for Network reduction and PSCAD conversion

asked 2016-02-01 13:16:10 -0500

MW gravatar image

Hi all,

Can someone enlighten me on the subject of the pro's and cons between the two approaches to receive a reduced network model in PSCAD. The two options are below (if you have a better 3rd please feel free to add):

  1. By using SCEQ function in PSS/E reducing the network to a reasonable size. Compare V and angles in load flow as well as 3 ph and SLG faults with full and reduced network so they are close. Then use E-tran to convert the reduced network to a PSCAD network for PSCAD simulations (also validation performed against PSS/E data: V, angles, 3 ph, SLG, rotor angle response of generators if any included in .dyr-file)

  2. Use E-tran directly to both reduce and convert the network from PSS/E to PSCAD. In an E-tran information sheet they say it can be validated by performing a "network frequency scan" at the relevant bus. First using a reduced network 2 buses away, then 3 then 4 etc. until a nice approximation is received. (Source:

I guess if you have specific ideas on that you want to model 4 buses away on one end and 2 buses away on the other, 2. is not as efficient but also more specifically; Have anyone seen noticable differences in the simulation result between 1 and 2? Anyone with a link to some comparative study etc.?

Best regards MW

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I have used first approach only. I will try second one and let you know. (Earlier I thought E-tran creates some wide band equivalent for necessary frequency ranges.But these references show we can apply contingencies etc in retained network )

Mahesh gravatar imageMahesh ( 2016-02-06 14:29:14 -0500 )edit

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answered 2018-09-05 05:53:28 -0500

jfconroy gravatar image

I have used the second approach with ETRAN and PSCAD.

I had to go 6 buses away from the relevant bus, at which point there was no significant difference compared to the frequency sweep results (Impedance vs Frequency) using the 5 buses away option. Therefore, explicit representation of the network up to 5 buses away from the relevant bus gives sufficient accuracy. In your own study, the answer may be 3, 4, 5 or >5, but the approach should be the same.

You can also consider using the frequency dependent equivalent network element in PSCAD. With this element, you enter the results of the frequency sweep at the relevant bus, do some vector fitting, and then you have an equivalent representation of the external network that is valid for a large range of frequencies.

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Asked: 2016-02-01 13:16:10 -0500

Seen: 2,185 times

Last updated: Sep 05 '18