Three-Phase Source - Implement three-phase source with internal R-L impedance

Library

Electrical Sources

Description

The Three-Phase Source block implements a balanced three-phase voltage source with an internal R-L impedance. The three voltage sources are connected in Y with a neutral connection that can be internally grounded or made accessible. You can specify the source internal resistance and inductance either directly by entering R and L values or indirectly by specifying the source inductive short-circuit level and X/R ratio.

Dialog Box and Parameters

Phase-to-phase rms voltage

The internal phase-to-phase voltage in volts RMS (Vrms)

Phase angle of phase A

The phase angle of the internal voltage generated by phase A, in degrees. The three voltages are generated in positive sequence. Thus, phase B and phase C internal voltages are lagging phase A respectively by 120 degrees and 240 degrees.

Frequency

The source frequency in hertz (Hz).

Internal connection

The internal connection of the three internal voltage sources. The block icon is updated according to the source connection.

Select one of the following three connections:

`Y`	The three voltage sources are connected in Y to an internal floating neutral.
`Yn`	The three voltage sources are connected in Y to a neutral connection which is made accessible through a fourth terminal.
`Yg`	The three voltage sources are connected in Y to an internally grounded neutral.

Specify impedance using short-circuit level

Select to specify internal impedance using the inductive short-circuit level and X/R ratio.

3-phase short-circuit level at base voltage

The three-phase inductive short-circuit power, in volts-amperes (VA), at specified base voltage, used to compute the internal inductance L. This parameter is available only if Specify impedance using short-circuit level is selected.

The internal inductance L (in H) is computed from the inductive three-phase short-circuit power Psc (in VA), base voltage Vbase (in Vrms phase-to-phase), and source frequency f (in Hz) as follows:

Base voltage

The phase-to-phase base voltage, in volts RMS, used to specify the three-phase short-circuit level. The base voltage is usually the nominal source voltage. This parameter is available only if Specify impedance using short-circuit level is selected.

X/R ratio

The X/R ratio at nominal source frequency or quality factor of the internal source impedance. This parameter is available only if Specify impedance using short-circuit level is selected.

The internal resistance R (in Ω) is computed from the source reactance X (in Ω) at specified frequency, and X/R ratio as follows:

Source resistance

This parameter is available only if Specify impedance using short-circuit level is not selected.

The source internal resistance in ohms (Ω).

Source inductance

This parameter is available only if Specify impedance using short-circuit level is not selected.

The source internal inductance in henries (H).

Note Either resistance or inductance of the source can be set to zero, but not both at the same time. The block icon is updated accordingly.

Example

See the power_3phseriescomp demo, which uses a Three-Phase Source block to model a portion of a 735 kV system with a simplified R-L source. The source impedance is specified by using the three-phase short-circuit level (30,000 MVA) and X/R ratio (X/R = 10).

Three-Phase Source - Implement three-phase source with internal R-L impedance

Library

Description

Dialog Box and Parameters

Example

See Also

Related Products & Applications