ST7C
Exc IEEE ST7C model
This article is incomplete, some sections must be written.
Context
This voltage regulator model first appeared in the IEEE Std 421.5-2016 (of Electrical & Engineers, 2016). It has been reproduced identically in the IEC 61970-302:2024 version (Commission, 2024). In the previous standard version (2005), its predecessor model was called ST7B. Compared to ST7B, ST7C has an additional time constant tA.
Model use, assumptions, validity domain and limitations
To be completed
Model inputs and output
The input variables are :
| Variable | Description | Units |
|---|---|---|
| UsPu | measured stator voltage | pu (base UNom) |
| UsRefPu | reference stator voltage | pu (base UNom) |
| UOelPu (optional) | output voltage of overexcitation limiter | pu (base UNom) |
| UPssPu (optional) | output voltage of power system stabilizer | pu (base UNom) |
| USclOelPu (optional) | output voltage of stator current overexcitation limiter | pu (base UNom) |
| USclUelPu (optional) | output voltage of stator current underexcitation limiter | pu (base UNom) |
| UUelPu (optional) | output voltage of underexcitation limiter | pu (base UNom) |
The output signal is EfdPu, the excitation voltage in pu (user-selected base voltage).
Model parameters
| Parameters | Description | Units |
|---|---|---|
| Kh | High-value gate feedback gain | pu |
| Kia | Voltage regulator feedback gain | pu |
| Kl | Low-value gate feedback gain | pu |
| Kpa | Voltage regulator proportional gain | pu |
| PositionOel | Input location : (0) none, (1) voltage error summation, (2) take-over at AVR input, (3) take-over at AVR output | - |
| PositionScl | Input location : (0) none, (1) voltage error summation, (2) take-over at AVR input, (3) take-over at AVR output | - |
| PositionUel | Input location : (0) none, (1) voltage error summation, (2) take-over at AVR input, (3) take-over at AVR output | - |
| tA | Thyristor bridge firing control equivalent time constant | s |
| tB | Voltage regulator lag time constant | s |
| tC | Voltage regulator lead time constant | s |
| tF | Stator voltage lag time constant | s |
| tG | Stator voltage lead time constant | s |
| tIa | Feedback time constant | s |
| tR | Stator voltage filter time constant | s |
| VMaxPu | Maximum reference voltage | pu (user-selected base voltage) |
| VMinPu | Minimum reference voltage | pu (user-selected base voltage) |
| VrMaxPu | Maximum field voltage | pu (user-selected base voltage) |
| VrMinPu | Minimum field voltage | pu (user-selected base voltage) |
Model diagram
Model variant
In the ST7B model, the final first order filter is ignored.
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 | 24/05/2024 |
References
- of Electrical, T. I., & Engineers, E. (2016). IEEE recommended practice for excitation system models for power system stability studies . IEEE Std 421.5-2016. https://home.engineering.iastate.edu/ jdm/ee554/IEEEstd421.5-2016RecPracExSysModsPwrSysStabStudies.pdf
- Commission, I. E. (2024). Energy management system application program interface (EMS-API) Part 302: Common information model (CIM) dynamics. IEC 61970-302. https://webstore.iec.ch/preview/info_iec61970-302%7Bed2.0%7Db.pdf