A Method for Measuring Grid Voltage Flicker

Abstract

The invention discloses a method for measuring electric network voltage flicker, and discloses a high-accuracy rapid flicker calculating method aiming at a non-integral cycle low sampling rate by taking account of errors probably caused by harmonic waves and electric network frequency. The core of the calculating method is that: a low fixed sampling rate is adopted to perform non-integral cycle sampling on electric network voltage waveforms, a cosine window is used for performing a fast Fourier transform algorithm (FFT), then the flicker frequency component is accurately extracted through a double-spectral line interpolation algorithm and a frequency spectrum searching algorithm, and the instantaneous flicker visual sensitivity is obtained through calculation. By using the method, under the condition of non-integral cycle low sampling rate, the errors caused by frequency spectrum leakage and harmonic wave aliasing are overcome, the frequency resolution is improved, the complexity of flicker calculation is effectively simplified, and a flicker measurement result is acquired quickly. By using the method, the performance requirement of hardware of an analog-digital converter, a processor and the like is reduced, thus the cost of a flicker measuring instrument is reduced, and simultaneously the measuring accuracy is improved; and besides, the method is applicable to fast low-cost measurement of the electric network voltage flicker, and has a very good effect.

Description

technical field [0001] The invention relates to a method for measuring grid voltage flicker, which belongs to the technical field of electric power. Background technique [0002] With the continuous development of the national economy, a large number of nonlinear high-power devices have entered the grid, causing grid pollution such as harmonics and flicker. In order to provide standards for the measurement of flicker, our country refers to the electromagnetic compatibility standard IEC61000-3-7 of the International Electrotechnical Commission, and issued the standard GB 12326-2000 "Power Quality Voltage Fluctuation and Flicker" in 2000, which was revised in 2008. IEC61000-4-15 provides the corresponding flicker test structure diagram and the transfer function of the human brain for frequency selection characteristics, but this method is more complicated, has higher requirements on the hardware platform, and has poor real-time performance. [0003] The calculation of flicker...

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Problems solved by technology

The document "Voltage Fluctuation and Flicker Calculation Method Based on High-precision FFT" (the 24th Joint Academic Annual Conference of the Power System Professional Committee of Seven Provinces (Districts) in Central and South China, 2009) proposed a flicker analysis method from the perspective of frequency domain Calculation method, but does not fully consider the impact of frequency resolution on flicker measurement

The spectrum analysis method proposed in the document "Flicker Value Measurement Method Based on Spectrum Analysis" ("Electrical Measurement and Instrumentation", 2010, 47(04):46~48) does not consider the error caused by grid harmonics to flicker measurement

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