Description

This module is based on the IEEE Std 412.5 type DC3A excitation system model [1]. This excitation system is used to represent older systems; to represent a non-continuous regulator for the DC commutator exciter. The voltage magnitude is periodically adjusted with a rheostat for small errors and is shorted or forced to a reference signal for large errors.

Mask and Parameters

AVR Parameters

DC3A-AVR mask parameters

Expanding the "DC2A diagram" displays the block diagram in the parameters window.

Name	Description	Unit
Tr	Regulator input filter time constant. This input filter is not part of the standard and there are no typical values recommended in [1]. It was added for flexibility. N.B. This parameter can be set to 0 if the filter is not used.	s
Kv	Fast raise/lower contact setting	s
Trh	Rheostat travel time	s
Vrmax	Maximum voltage regulator output	pu
Vrmin	Minimum voltage regulator output	pu

Exciter Parameters

Expanding the "Exciter diagram" displays the block diagram in the parameters window.

Name	Description	Unit
Te	Exciter time constant	s
Ke	Exciter constant related to self-excited field	-
Se1, Se2	Exciter saturation factor at the corresponding Vex	pu
ZEfd1, Efd2	Exciter voltage for the exciter saturation function	pu

Initial Values Mask Parameters

Name	Description		Unit
Efd0	Exciter output voltage initial value		pu

The parameter Efd0 can be set manually, by entering a numerical value. It can also be set automatically based on load flow calculations, by entering a referenced synchronous machine variable. For instance, if the name of the synchronous machine on which the excitation system is connected is “SM1”, then Efd0 shall be set as “=SM1.EfdInit” if a thermal machine or a hydraulic machine is used, and as "=SM1.EFD_Init" if a pu standard or pu fundamental machine is used.

The HYPERSIM® simulation option Set Initial Conditions must be checked for the automatic initialization to work properly.

Inputs and Outputs and Signals Available for Monitoring

Inputs

Name

Description

Unit

Vc1

Signal proportional to compensated terminal voltage

If a load compensator block is not used upstream from the exciter block, then Vc1 is equal to Vt (main alternator terminal voltage)

pu

Vref

Voltrage regulator reference voltage

pu

Outputs

Name	Description	Unit
Efd	Exciter output voltage	pu

References

1. “IEEE Recommended Practice for Excitation System Models for Power System Models for Power System Stability Studies,” IEEE Standard 421.5-2005.