A DIGITAL MEASUREMENT SCHEME FOR TIME-VARYING TRANSIENT HARMONICS

This paper presents an enhanced measurement scheme on the harmonics in power system voltages and currents which is not limited to stationary waveforms, but can also estimate harmonics in waveforms with time-var ying amplitudes, The paper starts with a review of the common techniqu es for harmonics measurement based on the Fast Fourier Transform (FFT) , The major pitfalls in the common FFT application techniques are desc ribed and the concepts of a new scheme for reducing the picket-fence e ffect are introduced, The proposed scheme is based on Parseval's relat ion and the energy concept which ''group harmonic'' identification for estimation the energy harmonics time-varying distribution in waveform s, The scheme is tested on a portable computer-based harmonic recorder providing onsite harmonic data collection and precise harmonic identi fication.