Abstract
Precise measurement of dielectric loss angle is very important for electric capacity equipment in recent power systems. When signal-to-noise is low and fundamental frequency is fluctuating, aiming at the measuring error of dielectric loss angle based on some recent Fourier transform and wavelet transform harmonics analysis method, we propose a novel algorithm based on sparse representation, and improved it to be more flexible for signal sampling. Comparison experiments describe the advantages of our method.
Highlights
In distributed monitor of the recent power systems, dielectric loss angle (DLA) plays a very important role in reflecting the insulating ability of high voltage electrical equipment, and on-line methods for measuring the electric capacity equipment mainly depend on DLA
Measuring the tangent value of DLA, tanδ=IR/IC, with software method is suitable with the field data sampled with hardware
Because frequency is fluctuating in power system and the entire cyclical sampling condition is difficult to satisfy in digital sampling, “stockade effect” and “frequency spectrum divulges” are arouse, which cause large errors when measuring the phase between the waves of voltage and current during the course of real measurement
Summary
In distributed monitor of the recent power systems, dielectric loss angle (DLA) plays a very important role in reflecting the insulating ability of high voltage electrical equipment, and on-line methods for measuring the electric capacity equipment mainly depend on DLA. Measuring the tangent value of DLA, tanδ=IR/IC, with software method is suitable with the field data sampled with hardware. In order to suppress the highordered harmonic, direct current and noise components, a high accuracy method is essential. Three state-of-the-art categroies of algorithms in DLA measurements with software methods are wave matching, filtering and harmonic analysising [1,2,3,4]. Computational cost and accrucay are two major concerns for the first two methods in realtime applications, and the last one, calculates tanδ with harmonic analysis [1,2,3] (e.g., Fourier transform, wavelet transform), is much more efficiency and not affected by high-ordered harmonic wave and zero-drift. In order to resolve the measure error in non-synchronous sampling, the windowed harmonic analysis is used [3].
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