Machine Inertia
Perfect rotational inertia.
Description
The Machine Inertia block simulates the inertia and damping that is connected to the mechanical rotation port R of a three-phase machine.
The block contains an in-built connection to the mechanical rotational network reference point. The figure shows an equivalent configuration of a Machine Inertia unit using mechanical rotational components.
Use the Specify inertia parameterization by parameter to specify the inertia directly or using the machine inertia constant .
If you specify the inertia constant for the machine, the block calculates the inertia as
,
where:
-
- inertia.
-
- inertia constant.
-
- rated total power of the connected machine.
-
- rated electrical frequency of the connected machine.
-
- number of pole pairs of the machine.
Damping is the viscous friction between the machine rotor and the reference point of the mechanical rotating network. Depending on the value selected for Specify damper parameterization by, you specify the damping factor in relative units or in SI units. If you specify a damping factor in relative units, the unit calculates the damping factor in SI units using these equations:
,
,
,
и
,
Where:
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- basic mechanical speed in rad/s.
-
- basic damping torque in Nm.
-
- basic damping coefficient in Nm/(rad/s).
-
- damping coefficient in relative units.
-
- damping coefficient in SI units Nm/(rad/s).
Parameters
Main
Rated apparent power, VA - rated apparent power
`555e6 V*A (by default)
Rated power.
Rated electrical frequency, Hz - rated electrical frequency, Hz
50 Hz (by default).
The rated electrical frequency for which the rated total power is specified.
Number of pole pairs - number of pole pairs
1 (By default).
Number of pole pairs of the machine.
Inertia
Specify inertia parameterization by - inertia parameterization
Inertia constant, H (by default) | Actual Inertia, J
Inertia type.
-
Inertia constant, His the inertia constant. -
Actual Inertia, J- actual rotational mechanical inertia of the machine rotor.
*Inertia constant, H is the constant of inertia
`3.525 s*W/VA (by default).
Inertia constant.
Dependencies
Used when Specify inertia parameterization by is set to Inertia constant, H.
Actual inertia, J - actual inertia
27548 kg*m^2 (by default).
Actual rotational mechanical inertia of the machine rotor. This parameter is only visible if the inertia parameterization by Specify inertia is set to Actual inertia, J.
Dependencies
Used when Specify inertia parameterization by is set to Actual Inertia, J.
Specify damper parameterization by - damping parameterization
Per-unit damping coefficient, pu_D (by default) | SI damping coefficient, D.
Unit type for the damping coefficient.
-
Per-unit damping coefficient, pu_D (by default)is the damping coefficient in relative units. -
SI damping coefficient, D- damping coefficient in SI units.
*Per-unit damping coefficient, D_pu - damping coefficient per unit
0.01 (by default).
Damping coefficient in relative units.
Dependencies
Used when Specify damper parameterization by is set to Per-unit damping coefficient, pu_D.
SI damping coefficient, D - damping coefficient
39.0509 Nm/(rad/s) (by default).
Damping coefficient in SI units.
Dependencies
Used when Specify damper parameterization by is set to SI damping coefficient, D.
Initial Conditions
Specify initialisation by - frequency initialisation
Initial electrical frequency (by default) | Initial mechanical frequency
Frequency type.
-
Initial electrical frequency- electrical frequency. -
Initial mechanical frequency- mechanical frequency.
*Initial electrical frequency - initial value of electrical frequency
50 Hz (By default).
Initial electrical frequency value.
Dependencies
Used when Specify initialisation by is set to Initial electrical frequency.
Initial mechanical frequency - initial value of mechanical frequency
50 Hz (By default).
Initial value of mechanical frequency.
Dependencies
Used when Specify initialisation by is set to Initial mechanical frequency.