TotalHarmonicDistortionOutput the total harmonic distortion (THD) 
This information is part of the Modelica Standard Library maintained by the Modelica Association.
This block determines the total harmonic distortion (THD) over the given period 1/f
.
Consider that the input u
consists of harmonic RMS components
U_{1}
, U_{2}
, U_{3}
, etc.
The total RMS component is then determined by:
The calculation of the total harmonic distortion is based on the parameter useFirstHarmonic
.
The default value useFirstHarmonic = true
represents the standard THD calculation used in
electrical engineering.
The nondefault value useFirstHarmonic = false
calculates the THD typically used for the assessment of audio signals.
If useFirstHarmonic = true
, the total higher harmonic content (harmonic order numbers > 1)
refers to the RMS value of the fundamental wave:
If useFirstHarmonic = false
, the total higher harmonic content (harmonic order numbers > 1)
refers to the total RMS:
In case of a zero input signal or within the first period of calculation, the boolean output signal
valid
becomes false
to indicate that the calculation result is not valid. Valid
calculations are indicated by valid = true
.
f 
Value: Type: Frequency (Hz) Description: Base frequency 

useFirstHarmonic 
Value: true Type: Boolean Description: THD with respect to first harmonic, if true; otherwise with respect to total RMS 
u 
Type: RealInput Description: Connector of Real input signal 


y 
Type: RealOutput Description: Connector of Real output signal 

valid 
Type: BooleanOutput Description: True, if output y is valid 
harmonic 
Type: Harmonic 


rootMeanSquare 
Type: RootMeanSquare 

greaterThreshold 
Type: GreaterThreshold 

division 
Type: Division 

limiter 
Type: Limiter 

pythagoras 
Type: Pythagoras 

andValid 
Type: And 

booleanExpression 
Type: BooleanExpression 

switch1 
Type: Switch 
Modelica.Blocks.Examples Calculation of total harmonic distortion of voltage 