Measure single-phase real and reactive power
Simscape / Power Systems / Simscape Components / Control / Measurements
The Power Measurement block measures the real and reactive power of an element in a single-phase network. The block outputs the power quantities for each frequency component you specify. For three-phase measurements, consider using the Three-Phase Power Measurement block.
Use this block to measure power for both sinusoidal and nonsinusoidal periodic signals.
Set the Sample time parameter to
continuous-time operation, or explicitly for discrete-time operation.
Specify a vector of all frequency components to include in the power output using the Harmonic numbers parameter:
To output the DC component, specify
To output the component corresponding to the fundamental frequency,
To output components corresponding to higher-order harmonics, specify
n > 1.
For each specified harmonic k, the block calculates the real power Pk and reactive power Qk from the phasor equation:
G is equal to
0.25 for the DC
component (k = 0) and
0.5 for the
AC components (k > 0).
is the phasor representation of the k-component input voltage.
is the complex conjugate of , the phasor representation of the k-component input current.
The block estimates the real-time k-component voltage and current phasors using these relationships:
V(t) and I(t) are the input voltage and current, respectively.
T is the period of the input signal, or equivalently the inverse of its base frequency F.
If the input signals have a finite number of harmonics n, the total real power P and total reactive power Q can be calculated from their components:
v— Input voltage
Voltage across element from which to measure power, in V.
i— Input current
Current through element from which to measure power, in A.
P— Real power
Real power for selected frequency components, in W.
P— Reactive power
Reactive power for selected frequency components, in var.
Base frequency (Hz)— Fundamental frequency
60(default) | positive number
Fundamental frequency corresponding to component k=1.
Harmonic numbers— Frequency components
[0 1 2 3](default) | scalar or vector
Frequency components to include in the output. Specify either a scalar value corresponding to the desired component or a vector of all desired components.
The value k = 0 corresponds to the DC component.
The value k = 1 corresponds to the fundamental frequency.
Values k > 1 correspond to higher-level harmonics.
If you specify a vector, the order of the power outputs correspond to the order of this vector.
Sample time— Block sample time
0(default) | positive number
Sample time for the block. For continuous operation, set this property to
0. For discrete operation, specify the sample time
explicitly. This block does not support inherited sample time.