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Three-Phase Programmable Voltage Source

Implement three-phase voltage source with programmable time variation of amplitude, phase, frequency, and harmonics

Library

Electrical Sources

Description

Use this block to generate a three-phase sinusoidal voltage with time-varying parameters. You can program the time variation for the amplitude, phase, or frequency of the fundamental component of the source. In addition, two harmonics can be programmed and superimposed on the fundamental signal.

Dialog Box and Parameters

Parameters Tab

Positive-sequence

The amplitude in volts RMS phase-to-phase, the phase in degrees, and the frequency in hertz of the positive-sequence component of the three voltages.

Time variation of

Specify the parameter for which you want to program the time variation. Select None if you do not want to program the time variation of the source parameters. Select Amplitude if you want to program the time variation of the amplitude. Select Phase if you want to program the time variation of the phase. Select Frequency if you want to program the time variation of the frequency.

The time variation applies to the three phases of the source except when the Type of variation parameter is set to Table of amplitude-pairs. In that case you can apply a variation to phase A only.

Type of variation

Specify the type of variation that is applied to the parameter specified by the Time variation of parameter. Select Step to program a step variation. Select Ramp to program a ramp variation. Select Modulation to program a modulated variation. Select Table of amplitude-pairs to program a series of step changes of amplitudes at specific times.

The Table of amplitude-pairs option is not available when the Time variation of parameter is set to Frequency.

Step magnitude

This parameter is visible only if the Type of Variation parameter is set to Step.

Specify the amplitude of the step change. The variation of amplitude is specified in pu of the positive-sequence amplitude.

Rate of change

This parameter is visible only if the Type of Variation parameter is set to Ramp.

Specify the rate of change, in volt/seconds. The rate of change of voltage is specified in (pu of the positive-sequence voltage)/second.

Amplitude of the modulation

This parameter is only visible if the Type of variation parameter is set to Modulation.

Specify the amplitude of the modulation for the source parameter that is specified in the Time variation of parameter. When the varying quantity is the voltage amplitude, the amplitude of the modulation is specified in pu of the positive-sequence amplitude.

Frequency of the modulation

This parameter is only visible if the Type of variation parameter is set to Modulation.

Specify the frequency of the modulation for the source parameter specified in the Time variation of parameter.

Variation timing(s)

Specify the time, in seconds, when the programmed time variation takes effect and the time when it stops.

Fundamental and/or Harmonic generation

If selected, two harmonics can be programmed to be superimposed on the fundamental voltage of the source.

A: [Order Amplitude Phase Seq]

This parameter is only visible if the Fundamental and/or Harmonic generation check box is selected.

Specify the order, amplitude, phase, and the type of sequence (1 = positive-sequence; 2 = negative-sequence; 0 = zero-sequence) of the first harmonic to be superimposed on the fundamental signal. The voltage of the harmonic is specified in pu of the positive-sequence voltage.

Specify 1 for the harmonic order and 0 or 2 for the sequence to produce a voltage imbalance without harmonics.

B: [Order Amplitude Phase Seq]

This parameter is only visible if the Fundamental and/or Harmonic generation check box is selected.

Specify the order, amplitude, phase, and the type of sequence (0 = zero sequence, 1 = positive sequence, 2 = negative sequence) of the second harmonic to be superimposed on the fundamental signal. The voltage of the harmonic is specified in pu of the positive-sequence voltage.

Specify 1 for the harmonic order and 0 or 2 for the sequence to produce a voltage unbalance without harmonics.

Variation Timing(s)

This parameter is visible only if the Fundamental and/or Harmonic generation check box is selected.

Specify the time, in seconds, when the harmonic generation is superimposed on the fundamental signal and the time when it stops.

Load Flow Tab

The load flow parameters are used to define block parameters for use with the Load Flow tool of the Powergui block. These load flow parameters are used for model initialization only. They have no impact on the block model and on the simulation's performance.

The configuration of the Load Flow tab depends on the option selected for the Generator type parameter.

Generator type

Specify the generator type of the voltage source.

Select swing to implement a generator controlling magnitude and phase angle of its terminal voltage. The reference voltage magnitude and angle are specified by the Swing bus or PV bus voltage and Swing bus voltage angle parameters of the Load Flow Bus block connected to the voltage source terminals.

Select PV to implement a generator controlling its output active power P and voltage magnitude V. P is specified by the Active power generation P parameter of the block. V is specified by the Swing bus or PV bus voltage parameter of the Load Flow Bus block connected to the voltage source terminals. You can control the minimum and maximum reactive power generated by the block by using the Minimum reactive power Qmin and Maximum reactive power Qmax parameters.

Select PQ to implement a generator controlling its output active power P and reactive power Q. P and Q are specified by the Active power generation P and Reactive power generation Q parameters of the block, respectively.

Active power generation P

Specify the active power that you want generated by the source, in watts. This parameter is available if you specify Generator type as PV or PQ.

Reactive power generation Q

Specify the reactive power that you want generated by the source, in vars. This parameter is available only if you specify Generator type as PQ.

Minimum reactive power Qmin

This parameter is available only if you specify Generator type as PV. Indicates the minimum reactive power that can be generated by the source while keeping the terminal voltage at its reference value. This reference voltage is specified in the Swing bus or PV bus voltage parameter of the Load Flow Bus block connected to the source terminals. The default value is -inf, which means that there is no lower limit on the reactive power output.

Maximum reactive power Qmax

This parameter is available only if you specify Generator type as PV. Indicates the maximum reactive power that can be generated by the source while keeping the terminal voltage at its reference value. This reference voltage is specified in the Swing bus or PV bus voltage parameter of the Load Flow Bus block connected to the source terminals. The default value is inf, which means that there is no upper limit on the reactive power output.

Example

The power_3phsignalseqpower_3phsignalseq circuit illustrates the use of the Three-Phase Programmable Voltage Source block to produce a step variation of the positive-sequence voltage and to inject harmonics into the circuit.

A 25 kV, 100 MVA short-circuit level, equivalent network feeds a 5 MW, 2 Mvar capacitive load. The internal voltage of the source is controlled by the Discrete 3-phase Programmable Voltage Source block.

A positive sequence of 1.0 pu, 0 degrees is specified for the fundamental signal. At t = 0.05 s a step of 0.5 pu is applied to the positive-sequence voltage magnitude, then at t = 0.1 s, 0.08 pu of fifth harmonic in negative sequence is added to the 1.5 pu voltage.

The three-phase voltage and current are measured at the output of the source impedance. Two Discrete Sequence Analyzer blocks are used to measure the positive-sequence fundamental component and the negative-sequence fifth harmonic of the three-phase voltage.

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