Description

IEEET3 model was developed based on the Type 3 excitation system specified in the IEEE committee report "Computer representation of excitation systems" [1][2]. The IEEET3 takes the generator terminal current as well as the potential as the excitation source [1].

Mask and Parameters

AVR parameters

Expanding the "IEEET3 diagram" displays the block diagram in the parameters window.

Name	Description	Unit	Parameter range
Tr	Regulator input filter time constant	s	--
Ka	Voltage regulator gain	-	--
Ta	Regulator time constant	s	--
Kf	Excitation control system stabilizer gain	-	--
Tf	Excitation control system stabilizer time constant 1	s	Tf1>=0.001
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	Parameter Range
Te	Exciter time constant	s	Te >= 0.04
Ke	Exciter constant related to self-excited field	--	--
Kp	Potential circuit gain coefficient proportional to voltage	--	--
Ki	Potential circuit gain coefficient proportional to current	--	--
Vbmax	Maximum field voltage	pu	--

Initial value tab

Name	Description	Unit	Hard coded parameters
Efd0	Exciter output voltage initial value	pu	--
Ifd0	Initial field current	pu	--

The parameters Ifd0 and 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”:

If a thermal machine or a hydraulic machine is used, Ifd0 shall be set as “=SM1.IfdInit” multiplied by the synchronous machine parameter Xad = Xd – Xl, and Efd0 shall be set as “=SM1.EfdInit”;
If a pu standard or pu fundamental machine is used, Ifd0 shall be set as “=SM1.IF_Init” and Efd0 shall be set as "=SM1.EFD_Init".

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

Inputs and Outputs and Additional Signals Available for Monitoring

Inputs

Name	Description	Unit
Vc1	Signal proportional to compensated terminal voltage If the Load Compensator block is not used upstream from the exciter block, then Vc1 is equal to Vt (main alternator terminal voltage)	pu
Vref	Voltage regulator reference voltage	pu
Vs	Is defined as the output voltage of a Power System Stabilizer (PSS) [1].	pu
Ifd**	Synchronous machine field current**	pu
Id	Active component of generator terminal current or component from load compensator	pu
Iq	Reactive component of generator terminal current or component from load compensator	pu
Vd	Active component of generator terminal voltage or component from load compensator	pu
Vq	Reactive component of generator terminal voltage or component from load compensator	pu
Vuel*	Under-excitation limiter output*	pu
Voel*	Over-excitation limiter output*	pu

*Vuel and Voel is normally an input to this excitation system but the user has the option to use a fixed constant value directly in the mask by choosing internal in the mask option.

**If a Synch. Machine (Hydraulic or Thermal) from the Network Machines and Generators library is used, the machine observable Ifd must be multiplied by the synchronous machine parameter Xad = Xd – Xl prior to its input to the exciter. This multiplication is not needed if a Synchronous Machine (pu Standard) or (pu Fundamental) is used.

Outputs

Name	Description	Unit
Efd	Exciter output voltage	pu

References

1. C. Report, "Computer representation of excitation systems," IEEE Transactions on Power Apparatus and Systems, pp. 1460-1464, June 1968

2. PSS®E 34.2.0 Model Library. NY, USA: Siemens Industry, Inc., 2017.