Power

Compute active and reactive powers of voltage-current pair at fundamental frequency

Libraries:
Simscape / Electrical / Specialized Power Systems / Sensors and Measurements

Description

The Power block computes the active power (P), in watts, and the reactive power (Q), in vars, of a voltage-current pair at fundamental frequency. To perform this computation, the block first determines the fundamental values (magnitude and phase) of the two input signals V & I. The following P and Q are then calculated:

$\begin{array}{l} P = \frac{| V |}{\sqrt{2}} \times \frac{| I |}{\sqrt{2}} \times \cos (φ) \\ Q = \frac{| V |}{\sqrt{2}} \times \frac{| I |}{\sqrt{2}} \times \sin (φ) \\ φ = ∠ V - ∠ I \end{array}$

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 outputs are held constant using the values specified by the Voltage initial input and Current initial input parameters.

Examples

The power_Power model shows the accuracy of the Power block in evaluating the active and reactive powers of a voltage-current set.

The model sample time is parameterized by the Ts variable set to a default value of 50e-6 s. Set Ts to 0 in the command window to simulate the model in continuous mode.

Characteristics

Sample Time	Specified in the Sample Time parameter Continuous if Sample Time = 0
Scalar Expansion	Yes, of the parameters
Dimensionalized	Yes

Ports

Input

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V — Voltage signal
scalar

The voltage signal.

I — Current signal
scalar

The current signal.

Output

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P — Active power
scalar

The active power of voltage-current pair signal, in watts.

Q — Reactive power
scalar

The reactive power of voltage-current pair signal, in vars.

Parameters

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Fundamental frequency (Hz) — Input signal fundamental frequency
`60` (default) | positive scalar

Specify the fundamental frequency, in hertz, of the input signals.

Voltage initial input [ Mag, Phase (degrees) ] — Initial voltage magnitude and phase
`[1, 0]` (default) | two-element vector

Specify the voltage initial magnitude and phase to set a constant output for the first cycle of simulation.

Current initial input [ Mag, Phase (degrees) ] — Initial current magnitude and phase
`[1, 0]` (default) | two-element vector

Specify the current initial magnitude and phase to set a constant output for the first cycle of simulation.

Sample time — Block sample time
`0` (default) | nonnegative scalar

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

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2013a

Power

Description

Examples

Characteristics

Ports

Input

V — Voltage signal scalar

I — Current signal scalar

Output

P — Active power scalar

Q — Reactive power scalar

Parameters

Fundamental frequency (Hz) — Input signal fundamental frequency 60 (default) | positive scalar

Voltage initial input [ Mag, Phase (degrees) ] — Initial voltage magnitude and phase [1, 0] (default) | two-element vector

Current initial input [ Mag, Phase (degrees) ] — Initial current magnitude and phase [1, 0] (default) | two-element vector

Sample time — Block sample time 0 (default) | nonnegative scalar

Extended Capabilities

C/C++ Code Generation Generate C and C++ code using Simulink® Coder™.

Version History

V — Voltage signal
scalar

I — Current signal
scalar

P — Active power
scalar

Q — Reactive power
scalar

Fundamental frequency (Hz) — Input signal fundamental frequency
`60` (default) | positive scalar

Voltage initial input [ Mag, Phase (degrees) ] — Initial voltage magnitude and phase
`[1, 0]` (default) | two-element vector

Current initial input [ Mag, Phase (degrees) ] — Initial current magnitude and phase
`[1, 0]` (default) | two-element vector

Sample time — Block sample time
`0` (default) | nonnegative scalar

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.