Synchronous Generator's Transient And Subtransient Time Constant

ETAP Knowledge Base

Synchronous Generator's transient and subtransient time constant Description: Synchronous Generator's transient and subtransient time constant Category:

Dynamic Model

Type: Keywords:

Synchronous Generator, Dynamic Model, Subtransient and transient time constant

Question: What is the relationship between open-circuit and short-circuit subtransient/transient time constants? Answer: Subtransient and transient time constants of synchrnous generator’s model in ETAP are based on open-circuit studies. This model is based on IEEE standard 1110.

For cases where manufacturer provides time constants based on short-circuit studies, standard suggests following relationship to approximate those values:

This document is confidential and proprietary to Operation Technology, Inc. and may not be reproduced, published or disclosed to others without the written authorization of Operation Technology, Inc., 17 Goodyear, Suite 100, Irvine, CA 92618, USA. © 2011 by Operation Technology, Inc. All Rights Reserved.

© Operation Technology, Inc.

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ETAP Knowledge Base

Synchronous Generator's transient and subtransient time constant

Where Reactances with subscript “u” are measured in unsaturated conditions. Subscript “v” applies to quantities appropriate for large current variations associated with faults; for example, sudden three-phase short circuit from rated terminal voltage. Since most stability studies are carried out with flux conditions (pre-fault or pre-disturbance) corresponding to rated terminal voltage, rated-voltage values of the transient and subtransient reactances ( X’dv and X’dv) are usually implied when X’d and X”d are specified [IEEE 1110, 2002]. These subtransient, transient manufacturers.

and synchronous reactances should be provided by

This document is confidential and proprietary to Operation Technology, Inc. and may not be reproduced, published or disclosed to others without the written authorization of Operation Technology, Inc., 17 Goodyear, Suite 100, Irvine, CA 92618, USA. © 2011 by Operation Technology, Inc. All Rights Reserved.

© Operation Technology, Inc.

Page 2 of 2

ETAPKB