IEC電壓閃爍規範61000-4-15係以模擬視覺對光線變化之反應，評估閃爍的嚴重程度，以 值為1.0作為閃爍的門檻值。所提出的演算法涵蓋白熾燈發光物理特性、視覺對燈光閃爍之敏感度以及視覺暫留等生理效應之模擬，能完整的表達出燈光、視覺的響應。
電力電子設備切換所產生的間諧波亦會引起電壓閃爍。然而，IEC電壓閃爍量測程序卻無法檢出由超過102Hz之間諧波所引起的閃爍。乃因其平方解調與帶通濾波設計，會將該間諧波的成分予以濾除。
既有文獻尚無有效方法可以萃取包含間諧波之電壓閃爍的波動包絡線，為解決此困難，本論文提出「擴頻式包絡線萃取法」，本法以Hilbert轉換為基礎，並根據間諧波閃爍的頻率特性輔以頻譜修剪，以取代IEC電壓閃爍量測程序中的平方解調與帶通濾波器，如此，得以萃取由間諧波造成之電壓閃爍的波動包絡線。
經與IEC電壓閃爍量測程序相比對，「擴頻式包絡線萃取法」可以檢出調幅波閃爍，檢出結果與IEC電壓閃爍量測程序之檢出結果相同。至於在間諧波閃爍的檢測部分，「擴頻式包絡線萃取法」優於IEC電壓閃爍量測程序。乃因「擴頻式包絡線萃取法」可以有效檢出由間諧波引起的閃爍。本研究亦評估新法的缺陷，若有雜訊與頻率漂移，則產生誤差，經由測試分析，建議修改前置電壓波形整理裝置以適當衰減或濾除雜訊並修正頻率漂移引起之誤差。

International Electrotechnical Committee Standard, IEC Std. 61000-4-15, gives functional and design specifications for a flickermeter which is the simulation process based on the response of human’s visual perception to the fluctuation of light. The simulation process, which includes square multiplier, band-pass filter, weighting filter, first-order sliding mean filter and statistic calculation of instantaneous flicker level curve (IFL), can effectively estimates value to assess the severity of voltage flicker.
Interharmonics are spectra components whose frequencies are not integral number of the system fundamental frequency. When a voltage waveform contains interharmonics, the RMS value and the magnitude of the waveform will fluctuate. This fluctuating magnitude is essentially a form of voltage flicker. If the magnitude is sufficiently large and the fluctuation frequency is in a range perceptible by human eyes, a light flicker will occur.
The IEC flicker meter has been widely applied to processing the waveform to measure the severity of flicker. However, the meter has a major deficiency: it is unable to measure flickers caused by interharmonics whose frequencies are higher than 102Hz.
This thesis proposes an envelope detection method which is based on the Hilbert transform and the spectrum processing to detect the envelope system voltage flicker which contains the flicker caused by interharmonics. The proposed method can effectively replace of the envelope extraction function (which encompasses squaring demodulator and the band-pass filter) of IEC flickermeter and make it possible to assess the voltage flicker caused by interharmonics.
The performance of the IEC metering procedure and the proposed method are compared. The comparison shows that the proposed method can work well with the system voltage containing the interharmonics whose frequencies are larger than 102Hz. The test also investigates the deficiency of proposed method and suggests future modification on the pre-processor of voltage to enhance the noise immunity and measuring stability of proposed method.

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