UEL2C
IEEE UEL2C model
Context
This underexcitation limiter model first appeared in the IEEE Std 421.5-2016 [1].
Model use, assumptions, validity domain and limitations
This model is associated to one of the voltage regulators (types AC, DC, ST) defined by the IEEE Std 421.5-2016 [1].
The model provides an underexcitation limiter signal for the purpose of takeover : the underexcitation limiter signal acts as a lower limit on the voltage regulator main signal which then becomes the excitation voltage.
Model inputs and output
The input signals are :
| Variable | Description | Unit |
|---|---|---|
| \(PGenPu\) | Active power generated by the synchronous machine | \(pu\) (base \(SnRef\)) |
| \(QGenPu\) | Reactive power generated by the synchronous machine | \(pu\) (base \(SnRef\)) |
| \(utPu\) | Complex stator voltage | \(pu\) (base \(UNom\)) |
| \(VFbPu\) | Reference voltage from ST7C | \(pu\) (base \(UNom\)) |
| \(VfPu\) | Excitation system stabilizer signal | \(pu\) |
Both \(PGenPu\) and \(QGenPu\) follow the generator convention.
The output signal is \(UUelPu\), the underexcitation limiter voltage in \(pu\) (base \(UNom\)).
Model parameters
| Parameter | Description | Unit | Value |
|---|---|---|---|
| \(K1\) | Voltage exponent for active power input to UEL table | \(-\) | \(2\) |
| \(K2\) | Voltage exponent for reactive power output of UEL table | \(-\) | \(2\) |
| \(KFb\) | UEL gain of reference voltage from ST7C | \(pu\) | \(-\) |
| \(KFix\) | UEL fixed gain reduction factor | \(pu\) | \(1\) |
| \(Kuf\) | UEL excitation system stabilizer gain | \(pu\) | \(0\) |
| \(Kui\) | UEL integral gain | \(pu\) | \(0.5\) |
| \(Kul\) | UEL proportional gain | \(pu\) | \(0.8\) |
| \(Sw1\) | UEL logic switch for adjustable gain reduction | \(-\) | \(true\) |
| \(tAdj\) | UEL adjustable gain reduction time constant | \(s\) | \(3\) |
| \(tQRef\) | UEL reactive power reference time constant | \(s\) | \(0\) |
| \(tU1\) | UEL first lead time constant | \(s\) | \(0\) |
| \(tU2\) | UEL first lag time constant | \(s\) | \(0\) |
| \(tU3\) | UEL second lead time constant | \(s\) | \(0\) |
| \(tU4\) | UEL second lag time constant | \(s\) | \(0\) |
| \(tUl\) | UEL time constant of filter for reference voltage from ST7C | \(s\) | \(0\) |
| \(tUP\) | UEL active power filter time constant | \(s\) | \(5\) |
| \(tUQ\) | UEL reactive power filter time constant | \(s\) | \(0\) |
| \(tUV\) | UEL voltage filter time constant | \(s\) | \(5\) |
| \(VBiasPu\) | UEL voltage bias | \(pu\) (base \(UNom\)) | \(1\) |
| \(VUel1MaxPu\) | UEL maximum output | \(pu\) (base \(UNom\)) | \(0.25\) |
| \(VUel1MinPu\) | UEL minimum output | \(pu\) (base \(UNom\)) | \(0\) |
| \(VUel2MaxPu\) | UEL maximum output | \(pu\) (base \(UNom\)) | \(99\) |
| \(VUel2MinPu\) | UEL minimum output | \(pu\) (base \(UNom\)) | \(-99\) |
| \(VUiMaxPu\) | UEL PI control maximum output | \(pu\) (base \(UNom\)) | \(0.25\) |
| \(VUiMinPu\) | UEL PI control minimum output | \(pu\) (base \(UNom\)) | \(0\) |
| \(XqPu\) | UEL characteristic reactance | \(pu\) (base \(SnRef\), \(UNom\)) | \(-\) |
The UEL lookup table is defined by 5 pairs (active power, reactive power) in \(pu\), typically with the following values :
| \(P\) | \(Q\) |
|---|---|
| \(0\) | \(-0.31\) |
| \(0.3\) | \(-0.31\) |
| \(0.6\) | \(-0.28\) |
| \(0.9\) | \(-0.21\) |
| \(1.02\) | \(0\) |
Model diagram
Open source implementations
This model has been successfully implemented in :
| Software | URL | Language | Open-Source License | Last consulted date | Comments |
|---|---|---|---|---|---|
| Dynawo | Link | Modelica | MPL v2.0 | 09/10/2024 |