Excitation System (Power System Blockset)

Provide an excitation system for the synchronous machine and regulate its terminal voltage in generating mode.

Library

Machines

Description

The Excitation System block is a purely Simulink system implementing a DC exciter described in [1], without the exciter's saturation function. The basic elements that form the Excitation System block are the voltage regulator and the exciter.

The exciter is represented by the following transfer function between the exciter voltage Vfd and the regulator's output ef:

Dialog Box and Parameters

Low-pass filter time constant: The time constant Tr, in seconds (s), of the first-order system which represents the stator terminal voltage transducer.
Regulator: The gain Ka and time constant Ta, in seconds(s), of the first-order system representing the main regulator.
Exciter: The gain Ke and time constant Te, in seconds (s) of the first-order system representing the exciter.
Transient gain reduction time constants: The time constants Tb, in seconds (s), and Tc, in seconds (s), of the first-order system representing a lead-lag compensator.
Damping filter: The gain Kf and time constant Tf, in seconds (s), of the first-order system representing a derivate feedback.
Regulator output limits: Limits Efmin and Efmax are imposed to the output of the voltage regulator. The upper limit can be constant and equal to Efmax or variable and equal to the rectified stator terminal voltage Vtf times a proportional gain Kp. If Kp is set to zero, the former will apply. If Kp is set to a positive value, the latter will apply.
Initial conditions: The initial values of terminal voltage Vt0 (p.u.) and field voltage Vf0 (p.u.). When set correctly, they allow you to start the simulation in steady-state. Initial terminal voltage should normally be set to 1 p.u. Initial field voltage can be computed by the load flow utility of the Powergui block.

Example

See the Hydraulic Turbine and Governor block.

Inputs and Outputs

The first input of the block is the desired value of the stator terminal voltage. The following two inputs are the v_q and v_d components of the terminal voltage. The fourth input can be used to provide additional stabilization of power system oscillations. All inputs are in p.u. The output of the block is the field voltage Vf for the Synchronous Machine block (p.u).

References

[1] "Recommended Practice for Excitation System Models for Power System Stability Studies." IEEE Standard 421.5-1992, August 1992

Distributed Parameter Line Ground