Power (Positive-Sequence)

(To be removed) Compute positive-sequence active and reactive powers

The Specialized Power Systems library will be removed in R2026a. Use the Simscape™ Electrical™ blocks and functions instead. For more information on updating your models, see Upgrade Specialized Power System Models to use Simscape Electrical Blocks.

Library

Simscape / Electrical / Specialized Power Systems / Sensors and Measurements

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Description

The Power (Positive-Sequence) block computes the positive-sequence active power P (in watts) and reactive power Q (in vars) of a periodic set of three-phase voltages and currents. To perform this computation, the block first computes the positive sequence of the input voltages and currents with a running window over one cycle of the specified fundamental frequency. These formulas are then evaluated:

$$\begin{array}{c}P=3\times \frac{\left|V_1\right|}{\sqrt{2}}\times \frac{\left|I_1\right|}{\sqrt{2}}\times \cos (\phi )\\ Q=3\times \frac{\left|V_1\right|}{\sqrt{2}}\times \frac{\left|I_1\right|}{\sqrt{2}}\times \sin (\phi )\\ \phi =\angle V_1-\angle I_1\end{array}$$

V₁ is the positive-sequence component of input Vabc. I₁ is the positive-sequence component of input Iabc.

A current flowing into an RL circuit produces a positive P and a positive Q.

As this block uses a running average window, one cycle of simulation must complete before the outputs give the correct value. For the first cycle of simulation, the output is held constant using the values specified by the Voltage initial input and Current initial input parameters.

Parameters

Fundamental frequency (Hz)

Specify the fundamental frequency, in hertz, of the input signals. Default is 60.

Voltage initial input [ Mag, Phase (degrees) ]

Specify the voltage initial magnitude and phase used by the block to compute the constant output for the first cycle of simulation. Default is [0, 0].

Current initial input [ Mag, Phase (degrees) ]

Specify the current initial magnitude and phase used by the block to compute the constant output for the first cycle of simulation. Default is [0, 0].

Sample time

Specify the sample time of the block, in seconds. Set to 0 to implement a continuous block. Default is 0.

Inputs and Outputs

Vabc

The three-phase voltage signal.

Iabc

The three-phase current signal.

P

The positive-sequence active power, in watts.

Q

The positive-sequence reactive power, in vars.

Characteristics

Sample Time	Specified in the Sample Time parameter Continuous if Sample Time = 0
Scalar Expansion	No
Dimensionalized	No

Version History

Introduced in R2013a