# Dynamic Load

Dynamic load for DC or AC supply

**Library:**Simscape / Electrical / Passive

## Description

The Dynamic Load block implements a dynamic load for a DC or AC supply.

If you set the **Load type** parameter to
`DC`

:

The consumed power of the block is equal to the

**P**port as long as it is greater than the value of the**Minimum consumed power**parameter and the voltage from the DC supply is equal to or greater than the value specified for the**Minimum supply voltage**parameter.When the voltage from the DC supply drops below the

**Minimum supply voltage**, the load behaviour changes and the block acts as a resistive load. If the supply voltage becomes negative, the block acts as an open circuit conductance.

To ensure smooth transitions between these behaviours, the block uses a third-order
polynomial spline with continuous derivatives. You can specify the width of this
transition using the **Transition voltage width** parameter.

If you set the **Load type** parameter to `AC`

,
this table shows the relationship between the voltage from the AC supply,
*V*, the active power at the **P** port,
*P _{in}*, and the consumed active power of
the block,

*P*:

_{actual}Applicable Range of V
Values | Applicable Range of
P Values_{in} | Corresponding Consumed Active Power |
---|---|---|

$$V>{V}_{\mathrm{min}}$$ | $${P}_{in}>{P}_{\mathrm{min}}$$ | $${P}_{actual}={P}_{in}$$ |

$${P}_{in}<{P}_{\mathrm{min}}$$ | $${P}_{actual}={P}_{\mathrm{min}}$$ | |

$$V<{V}_{\mathrm{min}}$$ | $${P}_{in}>{P}_{\mathrm{min}}$$ | The block models a load with an impedance equal to:$$\begin{array}{l}R={V}_{\mathrm{min}}^{2}\frac{{P}_{actual}}{{P}_{actual}{}^{2}+{Q}_{actual}{}^{2}}\\ X={V}_{\mathrm{min}}^{2}\frac{{Q}_{actual}}{{P}_{actual}{}^{2}+{Q}_{actual}{}^{2}}\\ Z=\sqrt{{R}^{2}+{X}^{2}}\end{array}$$ |

$${P}_{in}<{P}_{\mathrm{min}}$$ | $${P}_{actual}={P}_{\mathrm{min}}$$ |

Where:

*V*is the value of the Minimum supply voltage (RMS) parameter._{min}*P*is the value of the Minimum active power parameter._{min}*P*is the consumed active power of the Dynamic Load block._{actual}*Q*is the consumed reactive power of the Dynamic Load block._{actual}

The consumed reactive power of the block is equal to the **Q** port
as long as the voltage from the AC supply is equal to or greater than the value
specified for the **Minimum supply voltage (RMS)** parameter.
Otherwise, the block models a load with an impedance equal to:

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

.

### Faults

The Dynamic Load block allows you to model an electrical fault as an open circuit. The block can trigger fault events at a specific time.

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.

### Load-Flow Analysis

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

### Conserving

## Parameters

## Extended Capabilities

## Version History

**Introduced in R2020b**