The DC machine is modelled as a Norton equivalent which has a direct interface with the network component. The machine electrical parameters must be specified with real parameters (SI). The control of the machine can only be done externally through the mechanical speed or the mechanical torque.

The DC machine does not participate in the load flow

Mask and Parameters

The mask of the machine has two tabs:

Electrical Parameters: General parameters of the machine
Mechanical Data: Mechanical parameters of the machine

General Parameters tab

Name	Description	Unit
Base power	Nominal power	kW
Base Voltage	Nominal Voltage	kV
Ra	Armature resistance	Ohm
Laa	Armature inductance	H
Rf	Field resistance	Ohm
Lff	Field inductance	H
Laf	Mutual inductance	H

Mechanical Data tab

Name	Description	Unit
Control type	Mechanical torque or speed control	-
Moment of inertia J	Moment of inertia	kgm²
Friction Kd	Friction coefficient	Nm.s
Mechanical torque	User select if the mechanical torque characteristic is internal or external	-
Tmec	Torque points of the mechanical torque versus speed	Nm
Wmec	Speed points of the mechanical torque versus speed	rad/s

Ports, Inputs, Outputs and Signals Available for Monitoring

Ports

Name	Description
A+	DC machine positive connector of the armature. It supports single-phase connection.
A-	DC machine negative connector of the armature. It supports single-phase connection.
F+	DC machine positive connector of the field. It supports single-phase connection.
F-	DC machine negative connector of the field. It supports single-phase connection.

Inputs

Name	Description	Unit
	Torque or speed signal if the control is external	Nm or rad/s

Outputs

None

Sensors

Name	Description	Unit
Ias	Armature current	A
If	Field current	A
Ps	Consumed power	W
Tmec	Mechanical Torque	Nm
Tmec_i	Load torque or speed
Wm	Mechanical speed	rad/s
Wrpm	Mechanical speed	rpm

Additional Information & Model Equations

The equations below describe the dc machine:

The mechanical torque and the dynamic equation are described as follows:

The figures below show the shunt and serial connections of the DC machine.

Shunt DC machine:

Series DC machine:

Limitations

This model does not take into account the saturation.

References

Analysis of Electric Machinery and Drive Systems, 2^nd edition, Paul C. Krause, Oleg Wasynczuk, Scott D. Sudhoff.

Direct Current Machine