SimPowerSystems

Three-Phase V-I Measurement

Measure three-phase currents and voltages in a circuit

Library

Measurements

Description

The Three-Phase V-I Measurement block is used to measure three-phase voltages and currents in a circuit. When connected in series with three-phase elements, it returns the three phase-to-ground or phase-to-phase voltages and the three line currents.

The block can output the voltages and currents in per unit (p.u.) values or in volts and amperes. If you choose to measure the voltages and currents in p.u., the Three-Phase V-I Measurement block does the following conversions:

where V_baseLL is the base line-to-line voltage in volts RMS and P_base is the three-phase base power in volts-amperes. The two base values V_baseLL and P_base are specified in the Three-Phase Measurement block menu.

The steady-state voltage and current phasors measured by the Three-Phase V-I Measurement block can be obtained from the Powergui block by selecting Steady-State Voltages and Currents. The phasor magnitudes displayed in the Powergui stay in peak or RMS values even if the output signals are converted to p.u.

Dialog Box and Parameters

Voltage measurement

Select no if you do not want to measure three-phase voltage. Select phase-to-ground if you want to measure the phase-to-ground voltages. Select phase-to-phase if you want to measure the phase-to-phase voltages.

Use a label

If selected, the voltage measurements are sent to a labeled signal. Use a From block to read the voltages. The Goto tag of the From block must correspond to the label specified by the Signal label parameter. If not selected, the voltage measurements are available via the Vabc output of the block.

Signal label

Specifies a label tag for the voltage measurements.

Voltages in p.u.

If selected, the three-phase voltages are measured in p.u. Otherwise they are measured in volts.

Base voltage (Vrms phase-phase)

The base voltage, in volts RMS, used to convert the measured voltages in p.u. The Base voltage (Vrms phase-phase) parameter is not visible in the dialog box if Voltages in p.u. is not selected.

Current measurement

Select yes if you want to measure the three-phase currents that flow through the block.

Use a label

If selected, the current measurements are sent to a labeled signal. Use a From block to read the currents. The Goto tag of the From block must correspond to the label specified by the Signal label parameter. If not selected, the current measurements are available via the Iabc output of the block.

Signal label

Specifies a label tag for the current measurements.

Currents in p.u.

If selected, the three-phase currents are measured in p.u. Otherwise they are measured in amperes.

Base power (VA 3 phase)

The three-phase base power, in volt-ampere (VA), used to convert the measured currents in p.u. The Base power (VA 3 phase) parameter is not visible in the dialog box if Currents in p.u. is not selected.

Output signal

Specifies the format of the measured signals when the block is used in a phasor simulation. The Output signal parameter is disabled when the block is not used in a phasor simulation. The phasor simulation is activated by a Powergui block placed in the model.

Set to Complex to output the measured voltages and currents as complex values. The outputs are complex signals.

Set to Real-Imag to output the real and imaginary parts of the measured voltages and currents.

Set to Magnitude-Angle to output the magnitudes and angles of the measured voltages and currents.

Set to Magnitude to output the magnitudes of the measured voltages and currents. The output is a scalar value.

Inputs and Outputs

A, B, C a, b, c

Inputs A, B, C and outputs a, b, c are the phase connectors of the measurement block. Connect the Three-Phase V-I Measurement block in series with other three-phase electrical blocks.

Vabc

Simulink port Output 1 is a vector containing the three measured phase-to-ground or phase-to-phase voltages. The Vabc output disappears when the Use a label parameter is selected or when the Voltage measurement menu is set to no.

Iabc

Simulink port Output 2 is a vector containing the three measured line currents. The Iabc output disappears when the Use a label parameter is selected or when the Current measurement menu is set to no.

Example

See the power_3phseriescomp demo for a circuit using the Three-Phase V-I Measurement block.

Three-Phase Transformer (Three Windings)

Thyristor