Since R2019a

• Libraries:
Simscape / Electrical / Passive

## Description

The Dynamic Load (Three-Phase) block models a balanced dynamic load for a balanced three-phase supply.

This table shows how the block calculates the consumed active and reactive power based on the voltage from the supply, V.

Range of V ValuesConsumed Active and Reactive Power
$V>{V}_{\mathrm{min}}$$\begin{array}{l}{P}_{actual}={P}_{in}\\ {Q}_{actual}={Q}_{in}\end{array}$
$V<{V}_{\mathrm{min}}$

The block models a load with an impedance equal to:

$\begin{array}{l}R={V}_{\mathrm{min}}^{2}\frac{{P}_{in}}{{P}_{in}^{2}+{Q}_{in}^{2}}\\ X={V}_{\mathrm{min}}^{2}\frac{{Q}_{in}}{{P}_{in}^{2}+{Q}_{in}^{2}}\\ Z=\sqrt{{R}^{2}+{X}^{2}}\end{array}$

In these equations:

• Vmin is the value of the Minimum supply voltage (phase-to-phase RMS) parameter.

• Pactual is the consumed active power of the Dynamic Load (Three-Phase) block.

• Pin is the input active power of the Dynamic Load (Three-Phase) block, determined by external input port P.

• Qactual is the consumed reactive power of the Dynamic Load (Three-Phase) block.

• Qin is the input reactive power of the Dynamic Load (Three-Phase) block, determined by external input port Q.

The Dynamic Load (Three-Phase) block consumes or generates active power depending on the polarity of input active power Pin. If Pin > 0, the block consumes active power. If Pin < 0, the block generates active power.

### Faults

You can model an electrical fault as an open circuit and trigger a fault event at a specific time. To enable faults modeling, in the Faults section, set the Enable open circuit fault parameter to `On`. The block triggers the fault at the time specified in the Simulation time for fault event parameter.

You can also choose whether to issue an assertion when a fault occurs by using the Reporting when a fault occurs parameter. The assertion can take the form of a warning or an error. By default, the block does not issue an assertion.

If the block is in a network that is compatible with the frequency-time simulation mode, you can perform a load-flow analysis on the network. A load-flow analysis provides steady-state values that you can use to initialize a machine.

For more information, see Perform a Load-Flow Analysis Using Simscape Electrical and Frequency and Time Simulation Mode.

## Ports

### Input

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Physical signal port associated with real power, specified as a scalar.

Physical signal port associated with reactive power, specified as a scalar.

### Conserving

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Composite three-phase port associated with the three-phase voltage.

#### Dependencies

To enable this port, set Electrical connection to ```Composite three-phase ports```.

Expanded three-phase port associated with the phase A voltage.

#### Dependencies

To enable this port, set Electrical connection to ```Expanded three-phase ports```.

Expanded three-phase port associated with the phase B voltage.

#### Dependencies

To enable this port, set Electrical connection to ```Expanded three-phase ports```.

Expanded three-phase port associated with the phase C voltage.

#### Dependencies

To enable this port, set Electrical connection to ```Expanded three-phase ports```.

## Parameters

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### Main

Whether to model composite or expanded three-phase ports.

When you select `Composite three-phase ports`, the ~ conserving port represents a composite three-phase port.

When you select `Expanded three-phase ports`, the a, b, and c conserving ports represent the individual phases of a three-phase system.

Since R2023a

Rated electrical frequency.

Minimum voltage, in phase-to-phase RMS, that the supply needs for the block to act as a dynamic load.

Since R2023a

Time constant associated with the transients of the terminal voltage measurement.

Since R2023a

Terminal voltage, in phase-to-phase RMS, at time zero.

Since R2023a

Terminal voltage angle of phase A at time zero.

Since R2023a

Parasitic conductance to electrical reference.

### Faults

Select `On` to enable fault modeling and expose the associated parameters in the Faults section, which enables you to select the reporting method and specify the time at which the fault triggers.

Choose whether to issue an assertion when a fault occurs:

• `None` — The block does not issue an assertion.

• `Warn` — The block issues a warning.

• `Error` — Simulation stops with an error.

#### Dependencies

To enable this parameter, set Enable open circuit fault to `On`.

Simulation time when the block enters the faulted state.

#### Dependencies

To enable this parameter, set Enable open circuit fault to `On`.

Conductance during the open-circuit state.

#### Dependencies

To enable this parameter, set Enable open circuit fault to `On`.

## Version History

Introduced in R2019a

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