Description
This module is based on the IEEE std 412.5 type ST1A excitation system model [1]. The block diagram of a static excitation system model: the regulation is performed with a controlled rectifier, and a transformer is used for the excitation.
Mask and Parameters
AVR Parameters
Expanding the "ST1A 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. NB. This parameter can be set to 0 if the filter is not used. | pu | |
Tb, Tb1 | AVR lead-lag denominator time constants | pu | |
Tc, Tc1 | AVR lead-lag numerator time constants | pu | |
Ka | AVR filter gain | pu | |
Ta | AVR filter time constant | pu | |
Kf | Excitation control system stabilizer gain | pu | |
Tf | Excitation control system stabilizer time constant | pu | |
Vamax | Maximum regulator internal voltage | pu | |
Vamin | Minimum regulator internal voltage | pu | |
Vrmax | Maximum voltage regulator output | pu | |
Vrmin | Minimum voltage regulator output | pu | |
VImax | Maximum regulator input voltage | pu | |
VImin | Minimum regulator input voltage | pu |
Exciter Parameters
Expanding the "Exciter diagram" displays the block diagram in the parameters window.
Name | Description | Unit | |
---|---|---|---|
KLR | Exciter output current limiter gain | pu | |
ILR | Exciter output current limit reference | pu | |
Kc | Rectifier loading factor proportional to commutating reactance | pu |
Initial Values Mask Parameters
Name | Unit | Description |
Ifd0 | pu | Synchronous machine field current initial value |
Efd0 | pu | Exciter output voltage initial value |
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 Signals Available for Monitoring
Inputs
Name | Description | Unit |
---|---|---|
Voel^ | Overexcitation limiter output | pu |
Vc1 | Signal proportional to compensated terminal voltage. If the Load Compensator block is not used upstream from the exciter block, then Vc1 should be connected to Vt. | pu |
Vt | Machine terminal voltage | pu |
Vuel^ | Under-excitation limiter output* | 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 |
^Vuel and Voel are normally input to this excitation system, but the user can choose to use a fixed constant value directly in the mask by choosing internal in the mask option.
*A switch allows the users to select UEL input locations
- Summation point UEL ( at voltage error )
- HV gate 1
- HV gate 2
**A PSS input location switch
- Summation point at voltage error calculation
- Summation point at voltage regulator output
***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. “IEEE Recommended Practice for Excitation System Models for Power System Models for Power System Stability Studies,” IEEE Standard 421.5-2005.