Total Harmonic Distortion#

The Total Harmonic Distortion block calculates the total harmonic distortion (THD) of a periodic distorted signal. The input signal may be measured voltage or current.

The harmonic distortion factor is defined as the ratio of the root mean square value of the harmonics of the signal (except for the fundamental) to the root mean square value of the fundamental harmonic of the signal. For example, for an input current signal, the total harmonic distortion is calculated using the formula (1) :

(1)#\[THD=\frac{I_Г}{I_{Осн.}}\]

\(I_Г=\sqrt{I_2^2+I_3^2+...+I_n^2}\),

where:

\(I_n\) - root mean square value of the harmonic with number;

\(I_{Main}\) - root mean square value of the main (first) harmonic of the signal.

Important

The harmonic distortion factor for a pure sinusoidal signal will be equal to 0.

1. Properties#

Property	Default Value	Description	Units of measurement
Fundamental frequency	50.0	-	Hz
Sampling type: Fundamental project frequency decimation; Sample time; Sampling frequency	Fundamental project frequency decimation	-	-
Decimation factor of project fundamental discretization frequency, available when selecting `Sampling type` - `Fundamental project frequency decimation`	1	-	-
Sample time, available when selecting `Sampling type` - `Sample time`	0.05	-	s
Sampling frequency, available when selecting `Sampling type` - `Sampling frequency`	20.0	-	Hz

2. Inputs and outputs#

Parameters	Input/Output	Description	Units of measurement	Port type
Input signal	Input	-	-	Automation
Output signal	Output	-	-	Automation

In order to see the connection capabilities of the block, you need to go to page Description of block ports