ST1A Excitation System
Implements IEEE type ST1A excitation system model
Simscape / Electrical / Specialized Power Systems / Electrical Machines / Synchronous Machine Control
This block models an excitation system where the supply of power to the controlled bridge rectifier is provided by the generator terminals through a transformer to lower the voltage to an appropriate level. The voltage regulator gain and excitation system time constants are represented by Ka and Ta, respectively.
This block is an adaptation of the ST1A excitation system of the IEEE® 421 standard, copyright IEEE 2005, all rights reserved.
- Low-pass filter time constant
The time constant Tr of the first-order system representing the stator terminal voltage transducer. Default is
- Voltage regulator gain and time constant
The gain Ka and time constant Ta of the first-order system representing the main regulator. Default is
- Voltage regulator input limits
The voltage regulator input limits VImin and VImax, in p.u. Default is
- Voltage regulator internal limits
The voltage regulator internal limits VAmin and VAmax, in p.u. Default is
- Voltage regulator output limits
The voltage regulator output limits VRmin and VRmax, in p.u. Default is
- Damping filter gain and time constant
The gain Kf and time constant Tf of the first-order system representing the derivative feedback. Default is
- Transient gain reduction lead and lag time constants
The time constants Tb, Tc, Tb1, and Tc1 of the second-order system representing the lead-lag compensator. Default is
[0 0 0 0].
Exciter and Rectifier Tab
- Exciter output current limiter gain KLR
The exciter output current limiter gain. Default is
- Exciter output current limit reference ILR
The exciter output current limit reference. Default is
- Rectifier loading factor Kc
The rectifier loading factor proportional to commutating reactance. Default is
Initial Values Tab
- Initial values of terminal voltage and field voltage
The initial values of terminal voltage Vt0 and field voltage Efd0, both in p.u. Initial terminal voltage is normally set to 1 pu. The Vt0 and Efd0 values can be determined using the Powergui Load Flow tool. Default is
- Sample time
Specify a value greater than zero to discretize the block at the given sample time. Set to -1 to inherit the simulation type and sample time parameters of the Powergui block. Default is
The reference value of the stator terminal voltage, in p.u.
The measured value in p.u. of the stator terminal voltage of the controlled Synchronous Machine block.
The measured value in p.u. of the stator field current of the controlled Synchronous Machine block.
Connect this input to a power system stabilizer to provide additional stabilization of power system oscillations. When you do not use this option, connect to a Simulink® ground block. The input is in p.u.
The field voltage to apply to the
Vfinput of the controlled Synchronous Machine block. The output is in p.u.
power_machines example contains a Configurable
Subsystem block that allows you to select between seven types
of excitation systems to control the terminal voltage of the Synchronous
Machine block. This configurable block refers to the
library that contains seven pretuned excitation system blocks that
fit simulation requirements for this example.
Right-click the EXCITATION configurable block, then select ST1A from the Block Choice menu to control the Synchronous Machine block using the ST1A Excitation System block.
 “IEEE Recommended Practice for Excitation System Models for Power System Stability Studies.” IEEE Standard, Vol. 421, No. 5, 2005 (Revision of IEEE 521.5-1992).