谐波畸变计算器 — 公式
## Total Harmonic Distortion (THD)
THD quantifies how much the waveform deviates from a pure sinusoid.
### Formula
**THD = sqrt(V3^2 + V5^2 + V7^2 + ...) / V1 x 100%**
where V1 is the fundamental component and V3, V5, V7 are harmonic magnitudes. IEEE 519 recommends voltage THD below 5% at the point of common coupling for general systems.
THD quantifies how much the waveform deviates from a pure sinusoid.
### Formula
**THD = sqrt(V3^2 + V5^2 + V7^2 + ...) / V1 x 100%**
where V1 is the fundamental component and V3, V5, V7 are harmonic magnitudes. IEEE 519 recommends voltage THD below 5% at the point of common coupling for general systems.
计算示例
A 230V supply with 15V 3rd harmonic, 12V 5th, and 8V 7th.
- RSS harmonics = sqrt(225 + 144 + 64) = sqrt(433) = 20.81
- THD = 20.81 / 230 x 100 = 9.05%
- This exceeds the 5% IEEE 519 limit; mitigation is needed.