Contents

Three-Phase Parallel RLC Load

Implement three-phase parallel RLC load with selectable connection

Library

Elements

Description

The Three-Phase Parallel RLC Load block implements a three-phase balanced load as a parallel combination of RLC elements. At the specified frequency, the load exhibits a constant impedance. The active and reactive powers absorbed by the load are proportional to the square of the applied voltage.

Only elements associated with nonzero powers are displayed in the block icon.

Dialog Box and Parameters

Parameters Tab

Configuration

The connection of the three phases. Select one of the following four connections:

Y(grounded)

Neutral is grounded.

Y(floating)

Neutral is not accessible.

Y(neutral)

Neutral is made accessible through a fourth connector.

Delta

Three phases connected in delta

The block icon is updated according to the load connection.

Nominal phase-to-phase voltage Vn

The nominal phase-to-phase voltage of the load, in volts RMS (Vrms).

Nominal frequency fn

The nominal frequency, in hertz (Hz).

Active power P

The three-phase active power of the load, in watts (W).

Inductive reactive power QL

The three-phase inductive reactive power QL, in vars. Specify a positive value, or 0.

Capacitive reactive power QC

The three-phase capacitive reactive power QC, in vars. Specify a positive value, or 0.

Measurements

Select Branch voltages to measure the three voltages across each phase of the Three-Phase Parallel RLC Load block terminals. For a Y connection, these voltages are the phase-to-ground or phase-to-neutral voltages. For a delta connection, these voltages are the phase-to-phase voltages.

Select Branch currents to measure the three total currents (sum of R, L, C currents) flowing through each phase of the Three-Phase Parallel RLC Load block. For a delta connection, these currents are the currents flowing in each branch of the delta.

Select Branch voltages and currents to measure the three voltages and the three currents of the Three-Phase Parallel RLC Load block.

Place a Multimeter block in your model to display the selected measurements during the simulation. In the Available Measurements list box of the Multimeter block, the measurements are identified by a label followed by the block name.

Measurement

 

Label

Branch voltages

Y(grounded): Uag, Ubg, Ucg

Uag: , Ubg: , Ucg:

 

Y(floating): Uan, Ubn, Ucn

Uan: , Ubn: , Ucn:

 

Y(neutral): Uan, Ubn, Ucn

Uan: , Ubn: , Ucn:

 

Delta: Uab, Ubc, Uca

Uab: , Ubc: , Uca:

Branch currents

Y(grounded): Ia, Ib, Ic

Iag: , Ibg: , Icg:

 

Y(floating): Ia, Ib, Ic

Ian: , Ibn: , Icn:

 

Y(neutral): Ia, Ib, Ic

Ian: , Ibn: , Icn:

 

Delta: Iab, Ibc, Ica

Iab: , Ibc: , Ica:

Load Flow Tab

The parameters on this tab are used by 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 performance.

Load type

Specify the load type.

If you select constant Z, the load impedance is determined from the nominal phase-to-phase voltage Vn, active power P, and reactive power (QL-QC) specified on the Parameters tab of the block dialog box. During the load flow solution, the impedance is kept constant. The effective P and Q are therefore varying proportionally to the square of the bus voltage computed by the Load Flow tool.

If you select constant PQ, the active power P and reactive power Q are kept constant and equal to the values specified on the Parameters tab of the block dialog box. When you apply the load flow solution to the model (by clicking the Apply button of the Load Flow tool), the Nominal phase-to-phase voltage Vn parameter on the Parameters tab is automatically adjusted to the phase-to-phase bus voltage computed by the Load Flow tool.

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