Three-phase imbalance detection method for power grid

A balance detection, three-phase technology, applied in the fields of power electronics and signal processing, can solve the problems of spectrum leakage, the existence of the fence effect, and the difficulty of high-precision detection of three-phase unbalance in the power grid, achieving excellent attenuation speed and solving problems. Leakage and fence effect, the effect of improving the accuracy of detection results

Inactive Publication Date: 2019-05-31
CENT SOUTH UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

There have been patent No. 201510326063.0 "Fast Harmonic Analysis Method and System Based on Windowed Quadrogram Interpolation FFT", Application No. 201611151571.0 "A Windowed Interpolation FFT Harmonic Detection Algorithm", and Application No. 201810411526.7 " Harmonic detection method based on high-order Hanning self-convolution window and improved interpolation algorithm", patent number 201410142969.2 "Three-phase unbalance detection method and inverter based on FFT and symmetrical component method" and other authorizations, all concentrated in Harmonic detection method, and the spectrum leakage and fence effect still exist due to the fundamental frequency fluctuation in the power grid
Therefore, it is difficult to achieve high-precision detection of three-phase unbalance in the power grid.

Method used

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  • Three-phase imbalance detection method for power grid
  • Three-phase imbalance detection method for power grid
  • Three-phase imbalance detection method for power grid

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Embodiment Construction

[0045] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. The following examples are explanations of the present invention and the present invention is not limited to the following examples.

[0046] In this embodiment, the three-phase voltages are respectively:

[0047]

[0048] as an example

[0049] The implementation of the three-phase unbalance detection method for the power grid includes the following steps:

[0050] S1, through the A / D converter at the sampling frequency f s =3200 Sampling 10 cycles of the measured voltage and current signals in a three-phase four-wire system to obtain N=640 points of sampling data;

[0051] S2. The four-item third-order Nuttall self-convolution window function with the same length as the structure and the advantages of low side lobe level and fast attenuation speed is:

[0052] w N (n)=w(n)*w(n);

[0053] in:

[0054] n=0,1,2,...,N-1

[0055] a 0 =0.3...

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Abstract

The invention discloses a three-phase imbalance detection method for a power grid. According to the method, a new window function is constructed through self-convolution on the basis of a four-item third-order Nuttall window function with low sidelobe level and high decay speed; windowed FFT operation is performed on sampled data; a three-spectrum line interpolation algorithm is used to correct amplitudes and phases, so that the accuracy of detection results is improved; a symmetrical component method is used to calculate the zero-sequence, positive-sequence and negative-sequence components ofvoltages and current; and three-phase imbalance calculation is completed with high precision; the electric energy quality of a grid-connected point and a user end is monitored in real time; and a reliable data basis is provided for three-phase imbalance.

Description

technical field [0001] The invention relates to the technical field of signal processing, in particular to a three-phase unbalance detection method for a power grid, and is mainly applicable to the technical field of power electronics. Background technique [0002] With the extensive use of global energy and the pollution hazards caused by energy applications, the research on new energy technologies has received more and more attention and attention. A series of problems such as balance and harmonics have seriously affected the power quality of the grid. The three-phase unbalance problem in the low-voltage distribution network causes a series of hazards, including damage to the distribution transformer and increased line loss, resulting in a serious drop in the quality of the power supply voltage of the heavy-duty phase in the distribution area. Three-phase roughness detection is getting more and more attention and research. [0003] The Fast Fourier Transform (FFT) algori...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R29/16G01R23/16
Inventor 梁晓丁家峰李新梅
Owner CENT SOUTH UNIV
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