Total Harmonic Distortion

The Total Harmonic Distortion (total harmonic distortion, shortened THD) represents the variation of a signal compared to a reference.

Theory

The rate of harmonic distortion total describes the influence of the harmonic components of a signal:

$\{THD\}\; =\; \backslash \; sqrt\; \{\backslash \; sum\_\; \{h=2\}\; ^\; \{h=H\}\; \backslash \; left\; (\backslash \; frac\; \{Q\_h\}\; \{Q\_1\}\; \backslash \; right)\; ^2\}$

• Q_i : effective value of the current/the tension

• Q₁: basic component
• H: harmonic row
• H: maximum harmonic row, in theory infinite

This definition does not take into account the interharmonic components of the signal. One can then use the total report/ratio of distortion ( TDR ), definite like this:

$\{TDR\}\; =\; \backslash \; frac\; \{CCT\}\; \{Q\_1\}\; =\; \backslash \; frac\; \{\backslash \; sqrt\; \{Q^2\; -\; Q\_1^2\}\}\; \{Q\_1\}$

• Q₁ : effective value of the basic component

• Q: total effective value of the size (running or tension)

THD-F

The harmonic Taux of distortion compared to fundamental (THD-F) is defined as:

$\{THD-F\}\; =\; \backslash \; frac\; \{Vh\}\; \{Vf\}\; \backslash \; times\; 100$

with Harmonic Vh = effective Value of the S and effective Vf = Value of the fundamental

THD-G

The rate of harmonic distortion total (THD-G) is defined as:

$THD-G\; =\; \backslash \; frac\; \{Vh\}\; \{Vg\}\; \backslash \; times\; 100$

with Harmonic Vh = effective Value of the S and effective Vg = Value of the total signal

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