ETAp-Dynamic Models Excitation System

Dynamic Models Excitation System ETAP 24-27 ETAP 12.0 User Guide

24.4 Excitation System To accurately account for dynamics from exciter and AVR systems in power system transient responses, complete modeling of these systems is usually necessary. ETAP provides the following exciter and AVR models: IEEE Type 1 IEEE Type 2 IEEE Type 3 IEEE Type 1S IEEE Type DC1 IEEE Type DC2 IEEE Type DC3 IEEE Type ST1 IEEE Type ST2 IEEE Type ST3 IEEE Type AC1 IEEE Type AC2 IEEE Type AC3 IEEE Type AC4 IEEE Type AC5A Basler SR8F & SR125A HPC 840 JEUMONT Industrie IEEE Type ST1D IEEE Type AC8B IEEE Type AC1A IEEE Type ST4B IEEE Type DC4B IEEE Type AC7B IEEE Type ST1A IEEE Type AC2A IEEE Type ST2A User-defined Dynamic Model (UDM) For IEEE type exciter and AVR systems, the equivalent transfer functions and their parameter names are in accordance with the IEEE recommended types from the following references: IEEE Committee Report, “Computer Representation of Excitation System”, IEEE Trans. on PAS, Vol. PAS-87, No. 6, June 1968, pp 1460-1464. IEEE Committee Report, “Excitation System Models for Power System Stability Studies”, IEEE Trans. on PAS, Vol. PAS-100, No. 2, February 1981, pp 494-509. IEEE Std. 412.5-1992, “IEEE Recommended Practice for Excitation System Models for Power System Stability Studies”, IEEE Power Engineering Society, 1992.

Excitation System Saturation The following is a typical block diagram used for exciters:

Dynamic Models Excitation System ETAP 24-28 ETAP 12.0 User Guide

This diagram shows the output of the AVR is applied to the exciter after a saturation function SE is subtracted from it. The exciter parameter KE represents the setting of the shunt field rheostat when a selfexcited shunt field is used. It should be noted that there is a dependency between exciter ceiling Efdmax, AVR ceiling VRmax,

exciter saturation SE and exciter constant KE. These parameters are related by the following equation (the sign of KE is negative for a self-excited shunt field): VR – ( KE + SE ) Efd = 0 for Efdmin < Efd < Efdmax At excitation ceiling ( Efd = Efdmax ) the above equation becomes: VRmax = (KE +SEmax ) - Efdmax Therefore, it is important that the exciter parameters entered satisfy the above equation, when applicable. ETAP will check this condition at run time and flag any violations. The exciter saturation function (SE) represents the increase in exciter excitation due to saturation. It is defined as: where the quantities A and B are defined as the exciter field currents which produce the exciter output voltage on the constant-resistance-load saturation curve and air gap line, respective, as shown in the exciter saturation curve below ETAP assumes that SE is specified at the following exciter voltages: Saturation Factor Exciter Voltage SEmax Efdmax SE.75max 0.75Efdmax

Dynamic Models Excitation System IEEE Type (1) ETAP 24-29 ETAP 12.0 User Guide

24.4.1 IEEE Type 1 IEEE Type 1 - Continuously Acting Regulator and Exciter (1) This type of exciter and AVR system represents a continuously acting regulator with a rotating exciter system. Some vendors' units represented by this model include: Westinghouse Brushless Systems with TRA, Mag-A-Stat, Silverstat, or Rotoroal Regulator Allis Chalmers Systems with Regulex Regulator General Electric Systems with Amplidyne or GDA Regulator

Parameters and Sample Data Parameters for this model and their sample data are shown in this screen capture of the Exciter page:



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. SEmax The value of excitation function at Efdmax SE.75 The value of excitation function at 0.75 Efdmax Efdmax Maximum exciter output voltage p.u. KA Regulator gain p.u. KE Exciter constant for self-excited field p.u. KF Regulator stabilizing circuit gain p.u. TA Regulator amplifier time constant sec. TE Exciter time constant sec. TF Regulator stabilizing circuit time constant sec. TR Regulator input filter time constant sec.

Dynamic Models Excitation System

IEEE Type (2) ETAP 24-32 ETAP 12.0 User Guide

24.4.2 IEEE Type 2 IEEE Type 2 - Rotating Rectifier System (2) This type of exciter and AVR system represents a rotating rectifier exciter with static regulator system. Its characteristics are similar to IEEE Type 1 exciter, except for the feedback-damping loop. This system is applicable to units where the main input to the damping loop is provided from the regulator output rather than the exciter output. To compensate for the exciter damping which is not included in the damping loop, the feedback transfer function contains one additional time-constant. An example of such a system is the Westinghouse Brushless System, which was in service up to 1966.

Parameters and Sample Data Parameters for this model and their sample data are shown in the following screen capture:



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. SEmax The value of excitation function at Efdmax SE.75 The value of excitation function at 0.75 Efdmax Efdmax Maximum exciter output voltage p.u. KA Regulator gain p.u. KE Exciter constant for self-excited field p.u. KF Regulator stabilizing circuit gain p.u. TA Regulator amplifier time constant sec. TE Exciter time constant sec. TF1 Regulator stabilizing circuit first time constant sec. TF2 Regulator stabilizing circuit second time constant sec. TR Regulator input filter time constant sec.


24.4.3 IEEE Type 3 IEEE Type 3 - Static System with Terminal Potential and Current Supplies (3) This type of exciter and AVR system represents static excitation systems with compound terminal voltage and current feedback. The regulator transfer function for this model is similar to IEEE Type 1. In this model, the regulator output is combined with a signal, which represents the self-excitation from the generator terminals. An example of such a system is the General Electric SCPT System.


Dynamic Models Excitation System

IEEE Type (3) ETAP 24-36 ETAP 12.0 User Guide

Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. Vbmax Max. value of field voltage (saturated value) p.u. KA Regulator gain p.u. KE Exciter constant for self-excited field p.u. KF Regulator stabilizing circuit gain p.u. KI Current circuit gain coefficient (on system base – 100MVA) p.u. KP Potential circuit gain coefficient p.u. XL Reactance associated with potential source p.u. TA Regulator amplifier time constant sec. TE Exciter time constant sec.


TF Regulator stabilizing circuit second time constant sec. TR Regulator input filter time constant sec.

Dynamic Models Excitation System IEEE Type (1S) ETAP 24-38 ETAP 12.0 User Guide

24.4.4 IEEE Type 1S IEEE Type 1S - Controlled Rectifier System with Terminal Voltage (1S) In this type of exciter and AVR system, excitation is obtained through terminal voltage rectification. In this model, the maximum regulated voltage (VRmax) is proportional to terminal voltage Vt.




Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmin Minimum value of the regulator output voltage p.u. Efdmax The value of excitation function at Efdmax p.u. KA Regulator gain p.u. KF Exciter constant for self-excited field p.u. KP Regulator stabilizing circuit gain p.u. TA Regulator amplifier time constant sec. TF Regulator stabilizing circuit second time constant sec. TR Regulator input filter time constant sec.

Dynamic Models Excitation System IEEE Type (DC1) ETAP 24-41 ETAP 12.0 User Guide

24.4.5 IEEE Type DC1

IEEE Type DC1 - DC Commutator Exciter with Continuous Voltage Regulation (DC1) This type of exciter and AVR system is used to model field-controlled DC-Commutator exciters with continuous voltage regulators. Examples of this model are: Allis Chalmers Regulex regulator General Electric Amplidyne and GDA regulator Westinghouse Mag-A-Stat, Rototrol, Silverstat, and TRA regulators



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. SEmax The value of excitation function at Efdmax SE.75 The value of excitation function at 0.75 Efdmax Efdmax Maximum exciter output voltage p.u. KA Regulator gain p.u. KE Exciter constant for self-excited field p.u. KF Regulator stabilizing circuit gain p.u. TA Regulator amplifier time constant sec. TB Voltage regulator time constant sec. TC Voltage regulator time constant sec.


TE Exciter time constant Sec. TF Regulator stabilizing circuit time constant Sec. TR Regulator input filter time constant Sec.


24.4.6 IEEE Type DC2 IEEE Type DC2 - DC Commutator Exciter with Continuous Voltage Regulation and Supplies from Terminal Voltage (DC2) This type of exciter and AVR system is used for field-controlled DC commutator exciters with continuous voltage regulators supplied from the generator or auxiliary’s bus voltage. Its only difference from IEEE Type DC1 is the regulator output limits, which are now proportional to terminal voltage Vt.




Parameter Definitions and Units

Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. SEmax The value of excitation function at Efdmax SE.75 The value of excitation function at 0.75 Efdmax Efdmax Maximum exciter output voltage p.u. KA Regulator gain p.u. KE Exciter constant for self-excited field p.u. KF Regulator stabilizing circuit gain p.u. TA Regulator amplifier time constant sec. TB Voltage regulator time constant sec. TC Voltage regulator time constant sec. TE Exciter time constant sec. TF Regulator stabilizing circuit time constant sec. TR Regulator input filter time constant sec.


24.4.7 IEEE Type DC3 I EEE Type DC3 - DC Commutator Exciter with Non-Continuous Voltage Regulation (DC3) This type of exciter and AVR system is used for the older DC commutator exciters with noncontinuously acting regulators. Examples of this model are: General Electric exciter with GFA4 regulator Westinghouse exciter with BJ30 regulator



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. SEmax The value of excitation function at Efdmax SE.75 The value of excitation function at 0.75 Efdmax Efdmax Maximum exciter output voltage p.u.


KE Exciter constant for self-excited field p.u. KV Fast raise/Lower contact setting p.u. TE Exciter time constant sec. TR Regulator input filter time constant sec. TRH Rheostat travel time sec.

Dynamic Models Excitation System IEEE Type (ST1) ETAP 24-50 ETAP 12.0 User Guide

24.4.8 IEEE Type ST1 IEEE Type ST1 - Potential-Source Controlled-Rectifier Exciter (ST1) This type of exciter and AVR system is used to represent potential-source, controlled-rectifier excitation systems. This model applies to all systems supplied through a transformer from the generator terminals. Examples of this model include: Canadian General Electric Silcomatic exciters Westinghouse Canada Solid State Thyristor exciters Westinghouse type PS static excitation systems with type WTA or WHS regulators



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. VImax Maximum internal signal within voltage regulator p.u. VImin Minimum internal signal within voltage regulator p.u. KA Regulator gain p.u. KC Regulator gain p.u. KF Regulator stabilizing circuit gain p.u.


TA Regulator amplifier time constant sec. TB Voltage Regulator amplifier time constant sec. TC Voltage Regulator amplifier time constant sec. TF Regulator stabilizing circuit time constant sec. TR Regulator input filter time constant sec.


24.4.9 IEEE Type ST2 IEEE Type ST2 - Static System with Terminal Potential and Current Supplies (ST2) This type of exciter and AVR system is used for compound source rectifier excitation systems. These systems use both current and voltage sources. An example of this model is General Electric static exciter SCT-PPT or SCPT.



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. Efdmax Maximum exciter output voltage p.u.

KA Regulator gain p.u. KC Regulator gain p.u. KE Exciter constant for self-excited field p.u.


KF Regulator stabilizing circuit gain p.u. KI Current circuit gain coefficient (on system base – 100MVA) p.u. KP Potential circuit gain coefficient p.u. TA Regulator amplifier time constant sec. TE Exciter time constant sec. TF Regulator stabilizing circuit time constant sec. TR Regulator input filter time constant sec.


24.4.10 IEEE Type ST3 IEEE Type ST3 - Compound Source-Controlled Rectifier Exciter (ST3) This type of exciter and AVR system represents compound-source rectifier excitation systems. These exciters utilize internal quantities within the generator as the source of power. Examples of this model are: General Electric GENERREX exciter Shunt-Thyristor exciter



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. Efdmax Maximum exciter output voltage p.u. VGmax Maximum inner loop voltage feedback p.u. VImax Maximum internal signal within voltage regulator p.u. VImin Minimum internal signal within voltage regulator p.u.


KA Regulator gain p.u. KC Rectifier loading factor related to commutating reactance p.u. KG Inner loop feedback constant p.u. KI Current circuit gain coefficient (on system base – 100MVA) p.u. KJ First stage regulation gain p.u. KPreal Real part of potential circuit gain coefficient p.u. KPimg Reactive part of potential circuit gain coefficient p.u. TA Regulator amplifier time constant sec. TB Exciter time constant sec. TC Regulator stabilizing circuit time constant sec. TE Exciter time constant sec. TR Regulator input filter time constant sec. XL Reactance associated with potential source p.u.

Dynamic Models Excitation System IEEE Type (AC1) ETAP 24-59 ETAP 12.0 User Guide

24.4.11 IEEE Type AC1 IEEE Type AC1 - Alternator-Rectifier Exciter System with Non-Controlled Rectifiers and Field Current Feedback (AC1) This type of exciter and AVR system represents alternator-rectifier excitation systems with noncontrolled rectifiers and exciter field current feedback. There is no self-excitation and the source of voltage regulator power is not affected by external transients. Westinghouse Brushless Excitation Systems fall under this type of exciter model.



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. SEmax The value of excitation function at Efdmax SE.75 The value of excitation function at 0.75 Efdmax Efdmax Maximum exciter output voltage p.u.


KA Regulator gain p.u. KC Rectifier loading factor related to commutating reactance p.u. KD Demagnetizing factor p.u. KE Exciter constant for self-excited field p.u. KF Regulator stabilizing circuit gain p.u. TA Regulator amplifier time constant sec. TB Exciter time constant sec. TC Regulator stabilizing circuit time constant sec. TE Exciter time constant sec. TF Regulator stabilizing circuit time constant sec. TR Regulator input filter time constant sec.


24.4.12 IEEE Type AC2 IEEE Type AC2 - High-Initial-Response Alternator-Rectifier Exciter System (AC2) This type of exciter and AVR system represents high-initial-response, field-controlled alternatorrectifier excitation systems. The model uses an alternator main exciter and non-controlled rectifiers. It is similar to IEEE Type AC1 exciter model but has two additional field current feedback loops. An example of this model is Westinghouse High-Initial-Response Brushless Excitation System.



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. SEmax The value of excitation function at Efdmax SE.75 The value of excitation function at 0.75 Efdmax VAmax Maximum regulator internal voltage p.u. VAmin Minimum regulator internal voltage p.u.


Efdmax Maximum exciter output voltage p.u. KA Regulator gain p.u. KB Second stage regulator gain p.u. KC Rectifier loading factor related to commutating reactance p.u. KD Demagnetizing factor p.u. KE Exciter constant for self-excited field p.u. KF Regulator stabilizing circuit gain p.u.


Parameter Definition Unit KH Exciter field current feedback gain p.u. KL Gain of exciter field current limit p.u. TA Regulator amplifier time constant sec. TB Exciter time constant sec. TC Regulator stabilizing circuit time constants sec. TE Exciter time constant sec. TF Regulator stabilizing circuit time constant sec. TR Regulator input filter time constant sec. VLR Exciter field current limit reference


24.4.13 IEEE Type AC3 IEEE Type AC3 - Field-Controlled Alternator-Rectifier Exciter (AC3) This type of exciter and AVR system represents field-controlled, alternator-rectifier excitation systems. It can model systems that derive voltage regulator power from the exciter output voltage and simulate their non-linearity. An example of this model is General Electric ALTERREX excitation system using static voltage regulators.



Parameter Definitions and Units

Parameter definitions and their units are provided in the following table: Parameter Definition Unit SEmax The value of excitation function at Efdmax SE.75 The value of excitation function at 0.75 Efdmax Efdmax Maximum exciter output voltage p.u. EFDN Value of Efd at which feedback gain changes p.u. VAmax Maximum regulator internal voltage p.u. VAmin Minimum regulator internal voltage p.u.


VLV Exciter low voltage limit reference p.u. KA Regulator gain p.u. KC Rectifier loading factor related to commutating reactance p.u. KD Demagnetizing factor p.u. KE Exciter constant for self-excited field p.u. KF Regulator stabilizing circuit gain p.u. KLV Gain of the exciter low voltage limit signal p.u.


Parameter Definition Unit KN Exciter control system stabilizer gain p.u. TA Regulator amplifier time constant sec. TB Exciter time constant sec. TC Regulator stabilizing circuit time constant sec. TE Exciter time constant sec. TF Regulator stabilizing circuit time constant sec. TR Regulator input filter time constant sec. KR Constant for regulator and alternator field power supply p.u.


24.4.14 IEEE Type AC4 IEEE Type AC4 - High-Initial-Response Alternator-Supplied Controlled Rectifier Exciter (AC4) This type of exciter and AVR system represents alternator-supplied, controlled-rectifier excitation systems. A high-initial response excitation system, it has a Thyristor bridge at the output circuit. General Electric ALTHYREX and Rotating Thyristor excitation systems are examples of this type of exciter.



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. VImax The value of excitation function at Efdmax p.u. VImin The value of excitation function at 0.75 Efdmax p.u. KA Regulator gain p.u. KC Rectifier loading factor related to commutating reactance p.u.

TA Regulator amplifier time constant sec. TB Exciter time constant sec. TC Regulator stabilizing circuit time constant sec. TR Regulator input filter time constant sec.

Dynamic Models Excitation System AC5A ETAP 24-72 ETAP 12.0 User Guide

24.4.15 IEEE Type AC5A IEEE Type AC5A - Simplified Rotating Rectifier Excitation System (AC5A) This type of exciter and AVR system is a simplified model for brushless excitation systems. The regulator is supplied from a source, such as a permanent magnet generator, which is not affected by system disturbances. This model can be used to represent small excitation systems such as those produced by Basler and Electric Machinery.




Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. SEmax The value of excitation function at Efdmax SE.75 The value of excitation function at 0.75 Efdmax Efdmax Maximum exciter output voltage p.u. KA Regulator gain p.u. KE Exciter constant for self-excited field p.u. KF Regulator stabilizing circuit gain p.u. TA1 Voltage regulator time constant sec. TA2 Voltage regulator time constant sec. TA3 Voltage regulator time constant sec. TE Exciter time constant sec. TF1 Exciter control system time constant sec. TF2 Exciter control system time constant sec. TF3 Exciter control system time constant sec. TR Regulator input filter time constant sec.

Dynamic Models Excitation System Basler SR8F & SR125A ETAP 24-75 ETAP 12.0 User Guide

24.4.16 Basler SR8F & SR125A Basler SR8F & SR125A Excitation System (SR8F) This type of exciter and AVR system is used to represent Basler SR8F and SR125A Exciter Systems.


Parameters and Sample Data

Parameters for this model and their sample data are shown in the following screen capture:

Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. KA Regulator gain p.u. KF Regulator stabilizing circuit gain p.u. TA Regulator amplifier time constant sec.


TB Voltage regulator time constant sec. TF1 Regulator stabilizing circuit time constant sec. TF2 Regulator stabilizing circuit time constant (Rot. Rec.) sec. TR Regulator input filter time constant sec.

Dynamic Models Excitation System HPC 840 (HPC) ETAP 24-78 ETAP 12.0 User Guide

24.4.17 HPC 840 HPC 840 Excitation and AVR System (HPC) This type of exciter and AVR system includes both forward gain and feedback damping loops. There are three compensation signals that regulate excitation voltages. These signals are terminal voltage magnitude, real power generation, and reactive power generation.



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit Amax Regulator internal maximum limit (Amax = VImax * Ka) p.u. Amin Regulator internal minimum limit (Amin = VImin * Ka) p.u. Bmax Integrator upper limit (Bmax = LIMmax * Ka) p.u. Bmin Integrator lower limit (Bmin = LIMmin * Ka) p.u. C Combined excitation system (C = Kg * kp * Ka) p.u.


D Combined stabilizing feedback gain (D = Kd * Kf/Kp) p.u. Efdmax Maximum Exciter output voltage p.u. Kpow Active power compensation factor p.u. KQ Reactive power compensation factor p.u. KE Exciter constant for self-excited field p.u. SE .75 Value of excitation saturation function at 0.75 Efdmax SEmax Value of excitation saturation function at Efdmax TL Integration time constant sec. T4 Excitation system total delay sec. TD Stabilizing feedback time constant sec. Tdsty Voltage transducer filter time constant sec.

TE Exciter time constant sec. TF Regulator stabilizing circuit time constant sec. TP Active power compensation time constant sec. TQ Reactive power compensation time constant sec. VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. Control Bus Voltage feedback bus ID

Dynamic Models Excitation System JEUMONT Industrie (JEUM) ETAP 24-81 ETAP 12.0 User Guide

24.4.18 JEUMONT Industries JEUMONT - JEUMONT Industrie (JEUM) This type of exciter and AVR system consists of a voltage block, a current block, a voltage regulator block, and an excitation block. It uses a rotating rectifier for the excitation system.



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit AV1 Gain of voltage control loop AV2 Constant of voltage control loop sec. AV3 Constant of voltage control loop sec. AV4 Gain of voltage control loop AV5 Gain of reference voltage


AV6 Gain of voltage control loop AV7 Time constant of voltage control loop sec. AV8 Time constant of voltage control loop sec. AV9 Time constant of voltage control loop sec. AV10 Time constant of voltage control loop sec. AV11 Parameter of voltage control loop Ai1 Gain of current control loop Parameter Definition Unit Ai2 Gain of supply voltage to current control loop Ai3 Gain of current control loop Ai4 Gain of current control loop Ai5 Gain of current control loop Ai6 Gain of current control loop Ai7 Time constant of current control loop sec. Ai8 Time constant of current control loop sec. Ai9 Time constant of current control loop sec. Ai10 Time constant of current control loop sec. Ai11 Gain of current control loop Ai12 Time constant of current control loop sec. AR1 Gain of regulator AR2 Regulator reference KU1 Gain of terminal voltage feedback V KU2 Gain of regulator

Vres Supply voltage of thy-bridge V VSUP Supply voltage of current control loop V Te Time constant of exciter loop sec. Ke Gain of exciter loop SEmax Saturation coefficient at maximum field voltage SE.75max Saturation coefficient at 0.75 maximum field voltage Efdmax Maximum field voltage V Kae Gain of field current feedback loop Kif Gain of field current feedback V Max1 Maximum value 1 of voltage control loop V Min1 Minimum value 1 of voltage control loop V Max2 Maximum value 2 of voltage control loop V Min2 Minimum value 2 of voltage control loop V Max3 Maximum value 3 of voltage control loop V Min3 Minimum value 3 of voltage control loop V Max4 Maximum value 4 of current control loop V Min4 Minimum value 4 of current control loop V Max5 Maximum value 5 of current control loop V Min5 Minimum value 5 of current control loop V Max6 Maximum value 6 of current control loop V Min6 Minimum value 6 of current control loop V Max7 Maximum value 7 of current control loop V Min7 Minimum value 7 of current control loop V Control Bus Voltage feedback bus ID



24.4.19 IEEE Type ST1D IEEE Type ST1D- Static System with Terminal Potential and Current Supplies (ST1D) This type of exciter and AVR system is used for compound source rectifier excitation systems with voltsperhertz limiter. These systems use both current and voltage sources.



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit RC Resistive part of reactive droop compensation p.u. XC Inductive part of reactive droop compensation p.u. TR Transducer time constant sec. TC Transient gain reduction lead time constant sec. TB Transient gain reduction lag time constant sec. KA Amplifier gain p.u.


TA Amplifier time constant sec. KF Stabilizing feedback signal gain p.u. TF Stabilizing feedback signal time constant sec. KC Field current gain p.u. VVLR Set point of V/Hz limiter p.u. KVL Over-excitation feedback signal gain p.u. TVL Over-excitation feedback signal time constant sec.


Parameter Definition Unit KVF Stabilizing feedback signal gain p.u. TH Measurement time constant sec. VImax Maximum error limit p.u. VImin Minimum error limit p.u. VRmax Maximum regular output p.u. VRmin Minimum regular output p.u. Vdc Field flashing battery voltage volts Rf Field flashing battery and external circuit resistance ohms Vref Voltage reference p.u. TD Pickup delay time sec. VHZ V/Hz pickup value p.u. Ifb Exciter base current amps Vfb Exciter base voltage volts

Dynamic Models Excitation System IEEE Type (AC8B) ETAP 24-89 ETAP 12.0 User Guide

24.4.20 IEEE Type AC8B Parameters and Sample Data Parameters for this model and their sample data are shown in the following screen capture:



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum value of the regulator output voltage p.u. VRmin Minimum value of the regulator output voltage p.u. SEmax Saturation value of exciter at Efdmax p.u. SE.75 Saturation value of exciter at 0.75 Efdmax p.u. Efdmax Maximum exciter output voltage p.u. KP Proportional control gain p.u. KI Integral control gain p.u. KD Derivative control gain p.u. KA Regulator gain p.u. KE Exciter constant for self-excited field p.u. TD Derivative control time constant sec. TA Regulator amplifier time constant sec. TE Exciter time constant sec.

Dynamic Models Excitation System IEEE Type (AC1A) ETAP 24-92 ETAP 12.0 User Guide

24.4.21 IEEE Type AC1A IEEE Type AC1A Exciter (AC1A)



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VAmax Maximum value of the regulator output voltage p.u. VAmin Minimum value of the regulator output voltage p.u. VRmax Maximum regulator internal voltage p.u. VRmin Minimum regulator internal voltage p.u. VUEL Underexcitation limiter p.u.


VOEL Overexcitation limiter p.u. SEmax Saturation value of exciter at Efdmax p.u. SE.75 Saturation value of exciter at 0.75 Efdmax p.u. Efdmax Maximum exciter output voltage p.u. KA Regulate gain p.u.


Parameter Definition Unit KC Rectifier loading factor p.u. KD Demagnetizing factor p.u. KF Regulate stabilizing circuit gain p.u. KE Exciter gain p.u. TA Regulator amplifier time constant sec. TC Internal signal lead time constant sec. TB Internal signal lag time constant sec. TE Exciter time constant sec. TF Regulate stabilizing time constant sec. TR Regulate input filter time sec. a1 Rectifier regulation characteristic coefficient p.u. a2 Rectifier regulation characteristic coefficient p.u. b1 Rectifier regulation characteristic coefficient p.u. b2 Rectifier regulation characteristic coefficient p.u. b3 Rectifier regulation characteristic coefficient p.u. b4 Rectifier regulation characteristic coefficient p.u. b5 Rectifier regulation characteristic coefficient p.u. b6 Rectifier regulation characteristic coefficient p.u. b7 Rectifier regulation characteristic coefficient p.u. b8 Rectifier regulation characteristic coefficient p.u. b9 Rectifier regulation characteristic coefficient p.u. b10 Rectifier regulation characteristic coefficient p.u.

Dynamic Models Excitation System IEEE Type (ST4B) ETAP 24-96 ETAP 12.0 User Guide

24.4.22 IEEE Type ST4B IEEE ST4B Exciter



Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameter Definition Unit VRmax Maximum AVR output p.u. VRmin Minimum AVR output p.u. VMmax Maximum inner loop output p.u. VMmin Minimum inner loop output p.u. VBmax Maximum Source Voltage p.u.


VOEL Over excitation limit input p.u. VUEL Under excitation limit input p.u. KC Rectifier loading factor p.u. KG Field voltage feedback gain p.u. KI Current source constant (on system base – 100MVA) p.u. KPM Inner loop proportional gain p.u. KIM Inner loop integral gain p.u. KPR AVR proportional gain p.u. KIR AVR integral gain p.u. KPreal Real part of potential source constant p.u. KPimg Imaginary part of potential source constant p.u. TA AVR time constant sec. TR AC sensor time constant sec. XL Source leakage reactance p.u.

Dynamic Models Excitation System IEEE Type (DC4B) ETAP 24-99 ETAP 12.0 User Guide

24.4.23 IEEE Type DC4B IEEE Type DC4B – DC commutator exciter with PID style regulator




Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Note: Alternative VOEL and VUEL are considered as summation at the input of PID controller.

Parameters Description Unit VRmax Maximum controller output p.u. VRmin Minimum controller output p.u. VEmin Exciter minimum output voltage p.u. VOEL Overexcitation limiter output p.u. VUEL Underexcitation limiter output p.u. E1 Exciter flux at SE1 p.u. SE1 Saturation factor at E1 p.u. E2 Exciter flux at SE2 p.u. SE2 Saturation factor at E2 p.u. KP Regulator proportional gain p.u. KI Regulator integral gain p.u. KD Regulator derivative gain p.u. KF Rate feedback gain p.u. KE Exciter field proportional constant p.u. KA Regulator output gain p.u. TA Regulator output time constant sec. TF Rate feedback time constant sec. TD Regulator derivative filter time constant sec. TE Exciter field time constant sec. TR Regulator input filter time constant sec.


24.4.24 IEEE Type AC7B IEEE Type AC7B – Alternator-rectifier excitation system


Parameters and Sample Data Parameters for this model and their sample data are shown in the following screen capture: IEEE Type AC7B - Dataset 1


IEEE Type AC7B - Dataset 2


Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameters Description Unit VAmax Maximum voltage regulator output p.u. VAmin Minimum voltage regulator output p.u. VRmax Maximum voltage regulator output p.u. VRmin Minimum voltage regulator output p.u. VEmin Minimum available exciter voltage p.u. VFEmax Maximum fast exciter current limit p.u. VUEL Underexcitation limiter output p.u. E1 Exciter flux at SE1 p.u. SE1 Saturation factor at E1 p.u. E2 Exciter flux at SE2 p.u. SE2 Saturation factor at E2 p.u.

KPR Regulator proportional gain p.u. KIR Regulator integral gain p.u. KDR Regulator derivative gain p.u. KPA Voltage regulator proportional gain p.u. KIA Voltage regulator integral gain p.u. KP Potential circuit gain coefficient p.u. KL Low band gain p.u. KE Exciter constant related to self-excited field p.u. KD Demagnetizing factor, A function of exciter alternator reactances p.u. KF1 Excitation control system stabilizer gain p.u. KF2 Excitation control system stabilizer gain p.u. KF3 Rate feedback loop gain p.u. KC Rectifier loading factor proportional to commutating reactance p.u. TE Exciter time constant, integration rate associated with exciter control sec. TF Excitation control system stabilizer time constant sec. TDR Regulator derivative filter time constant sec. TR Regulator input filter time constant sec.

Dynamic Models Excitation System IEEE Type (ST1A) ETAP 24-106 ETAP 12.0 User Guide

24.4.25 IEEE Type ST1A IEEE Type ST1A – Potential-source, controlled-rectifier exciter


Parameters and Sample Data Parameters for this model and their sample data are shown in the following screen capture: IEEE Type ST1A - Dataset 1


IEEE Type ST1A - Dataset 2


Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Note: Alternative VUEL and stabilizer input are considered as summation at the input of controller. Parameters Description Unit VAmax Maximum voltage regulator output p.u. VAmin Minimum voltage regulator output p.u. VImax Maximum voltage regulator input limit p.u. VImin Minimum voltage regulator input limit p.u. VRmax Maximum voltage regulator output p.u. VRmin Minimum voltage regulator output p.u. VUEL Underexcitation limiter output p.u. VOEL Overexcitation limiter output p.u. KA Voltage regulator gain p.u. KC Rectifier loading factor proportional to commutating reactance p.u. KF Excitation control system stabilizer gain p.u.

KLR Exciter output current limiter gain p.u. ILR Exciter output current limit reference p.u. TB Voltage regulator time constant sec. TB1 Voltage regulator time constant sec. TC Voltage regulator time constant sec. TC1 Voltage regulator time constant sec. TA Voltage regulator time constant sec. TF Excitation control system stabilizer time constant sec. TR Regulator input filter time constant sec.


24.4.26 IEEE Type AC2A IEEE Type AC2A – High initial response alternator-rectifier excitation system with noncontrolled rectifiers and feedback from exciter field current




Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameters Description Unit VAmax Maximum voltage regulator output p.u. VAmin Minimum voltage regulator output p.u. VRmax Maximum voltage regulator output p.u. VRmin Minimum voltage regulator output p.u. VUEL Underexcitation limiter output p.u. VOEL Overexcitation limiter output p.u. VFEmax Maximum fast exciter current limit p.u. E1 Exciter flux at SE1 p.u. SE1 Saturation factor at E1 p.u. E2 Exciter flux at SE2 p.u. SE2 Saturation factor at E2 p.u. KA Voltage regulator gain p.u. KB Second stage regulator gain p.u. KC Rectifier loading factor proportional to commutating reactance p.u. KD Demagnetizing factor, A function of exciter alternator reactances p.u. KE Exciter constant related to self-excited field p.u. KF Excitation control system stabilizer gain p.u. KH Exciter field current feedback gain p.u. TA Voltage regulator time constant sec. TB Voltage regulator time constant sec. TC Voltage regulator time constant sec. TE Excitation time constant, integration rate associated with exciter control sec. TF Excitation control system stabilizer time constant sec. TR Regulator input filter time constant sec.


24.4.27 IEEE Type ST2A IEEE Type ST2A – Compound-source rectifier exciter




Parameter Definitions and Units Parameter definitions and their units are provided in the following table: Parameters Description Unit VRmax Maximum voltage regulator output p.u. VRmin Minimum voltage regulator output p.u. VUEL Underexcitation limiter output p.u. Efdmax Maximum exciter output voltage p.u. KA Voltage regulator gain p.u. KC Rectifier loading factor proportional to commutating reactance p.u. KE Exciter constant related to self-excited field p.u. KF Excitation control system stabilizer gain p.u. KI Regulator integral gain p.u. KP Potential circuit gain coefficient p.u. TA Voltage regulator time constant sec. TE Exciter time constant, integration rate associated with exciter control sec. TF Excitation control system stabilizer time constant sec. TR Regulator input filter time constant sec. Note: Alternative VUEL input is considered as summation at the input of controller. Note:

Dynamic Models Excitation System User-defined Dynamic Model (UDM) ETAP 24-116 ETAP 12.0 User Guide

24.4.28 User-defined Dynamic Model (UDM) You can access the UDM models that have been created and saved using the exciter type list. Details on how to use UDM models are described in User-defined Dynamic Models chapter.

ETAp-Dynamic Models Excitation System

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