# Three-Phase Dynamic Load

Implement three-phase dynamic load with active power and reactive power as function of voltage or controlled from external input

**Libraries:**

Simscape /
Electrical /
Specialized Power Systems /
Passives

## Description

The Three-Phase Dynamic Load block implements a three-phase, three-wire dynamic load whose active power P and reactive power Q vary as function of positive-sequence voltage. Negative- and zero-sequence currents are not simulated. The three load currents are therefore balanced, even under unbalanced load voltage conditions.

The load impedance is kept constant if the terminal voltage V of the load is lower than a specified value Vmin. When the terminal voltage is greater than the Vmin value, the active power P and reactive power Q of the load vary as follows:

$$\begin{array}{c}P(s)={P}_{0}{\left(\frac{V}{{V}_{0}}\right)}^{{n}_{p}}\frac{1+{T}_{p1}s}{1+{T}_{p2}s}\\ Q(s)={Q}_{0}{\left(\frac{V}{{V}_{0}}\right)}^{{n}_{q}}\frac{1+{T}_{q1}s}{1+{T}_{q2}s},\end{array}$$

where

*V*_{0}is the initial positive sequence voltage.*P*_{0}and Q_{o}are the initial active and reactive powers at the initial voltage V_{o}.*V*is the positive-sequence voltage.*n*and_{p}*n*are exponents (usually between 1 and 3) controlling the nature of the load._{q}*T*_{p1}and*T*_{p2}are time constants controlling the dynamics of the active power*P*.*T*_{q1}and*T*_{q2}are time constants controlling the dynamics of the reactive power*Q*.

For a constant current load, for example, you set
*n _{p}* to 1 and

*n*to 1, and for constant impedance load you set

_{q}*n*to 2 and

_{p}*n*to 2.

_{q}### Examples

The `power_dynamicload`

model uses a Three-Phase Dynamic Load block
connected on a 500 kV, 60 Hz power network.

## Ports

### Input

### Output

### Conserving

## Parameters

## Extended Capabilities

## Version History

**Introduced before R2006a**