ST7C

Voltage regulator

ST7C

generic

Opensource

CIM model

RMS

phasor

MRL4

Single phase

ExcIEEEST7C

IEEE

dynawo

#106

Author

Erwan Guichard (DPS for RTE)

Published

May 4, 2024

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 [1]. It has been reproduced identically in the IEC 61970-302:2024 version [2]. In the previous standard version (2005), its predecessor model was called ST7B. Compared to ST7B, ST7C has an additional time constant \(t_A\).

Model use, assumptions, validity domain and limitations

To be completed

Model inputs and output

The input variables are :

Variable	Description	Units
\(U_s P_u\)	measured stator voltage	\({pu}\) (base \(U N_{om}\))
\(U_{s} R_{ef} P_u\)	reference stator voltage	\({pu}\) (base \(U N_{om}\))
\(U_{Oel} P_u\) (optional)	output voltage of overexcitation limiter	\({pu}\) (base \(U N_{om}\))
\(U P_{ss} P_u\) (optional)	output voltage of power system stabilizer	\({pu}\) (base \(U N_{om}\))
\(U S_{cl} O_{el} P_u\) (optional)	output voltage of stator current overexcitation limiter	\({pu}\) (base \(U N_{om}\))
\(U S_{cl} U_{el} P_u\) (optional)	output voltage of stator current underexcitation limiter	\({pu}\) (base \(U N_{om}\))
\(U U_{el} P_u\) (optional)	output voltage of underexcitation limiter	\({pu}\) (base \(U N_{om}\))

The output signal is \(E_{fd} P_u\), the excitation voltage in \({pu}\) (user-selected base voltage).

Model parameters

Parameters	Description	Units
\(K_h\)	High-value gate feedback gain	\({pu}\)
\(K_{ia}\)	Voltage regulator feedback gain	\({pu}\)
\(K_l\)	Low-value gate feedback gain	\({pu}\)
\(K_{pa}\)	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	\(-\)
\(t_A\)	Thyristor bridge firing control equivalent time constant	\({s}\)
\(t U_{B1}\)	Second lag time constant	\({s}\)
\(t U_{B2}\)	First lag time constant	\({s}\)
\(t U_{C1}\)	Second lead time constant	\({s}\)
\(t U_{C2}\)	First lead time constant	\({s}\)
\(t_{I} a\)	Feedback time constant	\({s}\)
\(t_R\)	Stator voltage filter time constant	\({s}\)
\(V_{Max} P_u\)	Maximum reference voltage	\({pu}\) (user-selected base voltage)
\(V_{Min} P_u\)	Minimum reference voltage	\({pu}\) (user-selected base voltage)
\(V_{r} Max P_u\)	Maximum field voltage	\({pu}\) (user-selected base voltage)
\(V_{r} Min P_u\)	Minimum field voltage	\({pu}\) (user-selected base voltage)