Multi-Mass Torsional Shaft Interface

 Name for Identification

Text

Optional text parameter for identification of the component.

 For Use With...

Choice

Select Synchronous Machine, Induction Machine, DC Machine or PM Machine.

Number of Masses

INTEGER

Literal

Enter the number of turbines (1 to 25).  If 25 turbines are desired, the exciter mass cannot be modeled.

Machine Total MW

REAL

Constant

The 3-phase MW of the machine, to which the multi-mass is attached [MW]

Electrical Base Frequency

REAL

Constant

Enter electrical base frequency [Hz]

Machine Mechanical Synchronous Speed

REAL

Constant

Actual speed of the machine [rpm]

Machine Initial Electrical Speed

REAL

Constant

Initial speed of the machine [pu]

Unit System Number (see help)

Choice

Select 1 to 10.  See the table below for definitions

Initialization switch: 0-Init;1-Release

INTEGER

Variable

0-Initialization, 1-Release.  Until the switch turns 1 the generator will be spinning at the 'Machine rated speed' or at rated slip.  The variable name can come from the one assigned in the synchronous  machine under the Output Variables for Controller Initialization section of the input parameters.

Generator Mass Number

INTEGER

Literal

Enter the generator mass position number.

Unit System

Inertia Constant

Ji or Hi

Mutual Damping

MDij

Spring Constant

Kij

Torque Share

TFi

Self Damping

SDi

1

lb•ft•ft

-

lbf•ft/rad

pu

-

2

in•lbf•s2

-

lbf•in/rad

pu

-

3

lb•in•in

-

lbf•in/rad

pu

-

4a*

H [s]

-

pu

pu

-

4b*

H [s]

-

pu/rad

pu

-

5

kg•m•m

-

N•m/rad

pu

-

6

lb•ft•ft

lbf•ft•s/rad

lbf•ft/rad

pu

lbf•ft•s/rad

7

in•lbf•s2

lbf•in•s/rad

lbf•in/rad

pu

lbf•in•s/rad

8

lb•in•in

lbf•in•s/rad

lbf•in/rad

pu

lbf•in•s/rad

9a*

H [s]

pu

pu

pu

pu

9b*

H [s]

pu

pu/rad

pu

pu

10

kg•m•m

N•m•s/rad

N•m/rad

pu

N•m•s/rad

 Output Initialized Mechanical Torque

Choice

Select Yes or No.  This input could be used to initialize the governor/turbine and is available only if the For Use With... input parameter is set to Synchronous Machine

Input Initialized Steady Electrical Torque

Choice

Select Yes or No.  If the steady state Electrical Torque is available, this could be used to initialize the multi-mass and is available only if the For Use With... input parameter is set to Synchronous Machine.

 Mass # Inertia Constant

REAL

Constant

Enter the inertia constant for the corresponding mass

 Spring Constant From Mass # to #

REAL

Constant

The shaft spring constants are used to describe the dynamics of the shaft.  The torque exerted on the adjacent masses by the shaft is proportional to the relative mechanical angles between those masses.

 Torque Share for Mass #

REAL

Constant

The total mechanical torque applied to the multi-mass system may be distributed over the individual masses.  Each mass receives a fraction of the total mechanical torque: Its torque share.  The sum of the torque shares for all masses modeled (except the generator mass) must total 1 (one) [pu].

 Modal Damping for all Modes

REAL

Constant

A uniform modal damping factor for all modes.  This input is used only for Unit System Numbers 1 to 5.  The time constant for the decay of all modal oscillations is inverse of this [1/s]. In order to make the modal damping
uniform, the self damping coefficient (in per unit Torque or per unit Speed) is set to 4 times the uniform modal damping factor, times the inertia [s] for each mass. See Reference [47].

 Mass # Self Damping

REAL

Constant

The self-damping coefficient creates a torque on the appropriate mass which is proportional to the speed of the mass.  This may be used to represent friction and windage for the mass.  

 Damping Between Mass # & #

REAL

Constant

The mutual damping coefficient creates a torque, which is proportional to the difference in speed from one mass to the next.  Thus, this torque will not be applied in steady state, but will damp out oscillations between masses.

Torque on Shaft from Mass # - #

REAL

Output

Torque experienced by the shaft # [pu].

Mechanical Position  of Mass # Relative to Generator

REAL

Output

Mechanical position of mass # with respect to the generator [rad].

Rated Mechanical Speed of the System

REAL

Output

Rated mechanical speed [rad/s].

Delta Mechanical Speed of Mass #

REAL

Output

Difference between the rated speed and the speed of mass # [rad/s].