How to model over frequency relay tripping?

asked 2026-03-18 14:52:38 -0500

updated 2026-03-24 17:56:32 -0500

I am trying to model relay trip action to trip loads/feeders for over-frequency conditions in PSSE dynamic simulations. However, I can't seem to find any suitable model. Most relays are based on underfrequency

LDSHBL, LDSHOW, LDSHZN, LDSHAR, LDSHAL

The only over-frequency relay I found are the:

FRQDCAT, and FRQTPAT,

However, they only disconnect generators, or the whole bus. Is their any over-frequency relay that would trip a load or a percentage of a load?

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answered 2026-03-31 11:49:26 -0500

perolofl

3737 ●1 ●9 ●23

Do the following:

Split the load bus and move the load to be tripped to the new bus (LBUS). Change the bus code to 2.
Add a dummy generator at the load bus with Mbase=0.01, Qmax = Qmin = 0.
Add dynamic model GENCLS to the dummy generator with H=0.001.
Add dynamic model FRQDCAT with ICON(M)=LBUS, ICON(M+1)=LBUS and ICON(M+2)=generator id.

The load is now connected to a fictitious generator bus and model FRQDCAT can be used to trip the bus at overfrequency.

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Thanks @perolofl

Mohamed_M ( 2026-03-31 15:58:14 -0500 )edit

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Asked: 2026-03-18 14:52:38 -0500

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How to model over frequency relay tripping?

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