Dielectric loss on-line accurate measurement method based on phase factor transformation and interpolation

Abstract

The invention relates to a dielectric loss on-line accurate measurement method based on phase factor transformation and interpolation. The method includes following steps of: 1) performing digital sampling on voltages and currents at both ends of electric power capacitive devices, and obtaining discrete sampling values of the voltages and the currents; 2) performing discrete Fourier transform in which a Hanning window is added on the discrete sampling values of the voltages and the currents, and performing phase factor transform on frequency spectra of the voltages and the currents and obtaining new frequency spectra of the voltages and the current; 3) performing three-spectral line superposition and interpolation on fundamental components of the new frequency spectra of the voltages and the currents, and obtaining fundamental phase values of the voltages and the currents; and 4) performing conversion on the obtained fundamental phase values of the voltages and the current, and calculating a dielectric loss angle delta and a dielectric value tan delta. Compared with the prior art, the dielectric loss on-line accurate measurement method based on the phase factor transformation and interpolation is simple and accurate.

Description

technical field [0001] The invention relates to the field of measurement of electric variables, in particular to an on-line precise measurement method of dielectric loss based on phase factor transformation and interpolation. Background technique [0002] Dielectric loss tangent, as an indicator to comprehensively reflect the characteristics of dielectric loss, is an important reference quantity for measuring and monitoring the insulation performance of various power equipment. It can reflect the defects of equipment insulation such as moisture, cracking, and air gap discharge. An important item for system equipment failure and monitoring equipment insulation performance. In recent years, with the rapid development of electrical equipment status detection technology, people pay more and more attention to the on-line measurement technology of dielectric loss, so different methods have been formed. According to the different measurement methods and principles of dielectric lo...

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Problems solved by technology

At the same time, the frequency in the power system is in dynamic fluctuation, which makes it difficult to sample the voltage and current in the whole cycle, and the asynchronous sampling leads to the inability to completely eliminate the spectrum leakage

Aiming at the common fence effect and spectrum leakage problems in harmonic analysis methods, the literature "Measurement of Dielectric Loss Angle by High-Order Sine Fitting Method with Hanning Window Interpolation" (Authors: Xu Zhiniu, Lu Fangcheng, Wang Fochi, Li Heming, Gao Voltage Technology, 2007, 33(4): 50-53) proposed adding Hanning window interpolation to measure the dielectric loss angle, which improved the real-time performance and accuracy of the dielectric loss angle, and the algorithm realized the online measurement of the dielectric loss, but the angle measurement The accuracy is limited, and the measurement results will be greatly affected in the environment of high interference and large noise

[0004] Since the dielectric loss angle is generally very small, often between 0.001 and 0.02rad, it is easily affected by noise interference, asynchronous sampling and aperiodic signal truncation when it is measured online.

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