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Voltage flicker measuring method for wind generating set

A technology for wind power generators and voltage flicker, which is applied to measuring devices, measuring electrical variables, frequency measuring devices, etc., and can solve problems such as large measurement errors and inability to obtain flicker time and frequency and amplitude of flicker voltage

Inactive Publication Date: 2018-06-15
INNER MONGOLIA UNIV OF TECH
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The measurement error of IEC analog flicker meter, digital flicker meter and rectification detection method is large at low frequency and high frequency; the measurement error of instantaneous reactive power method, Teager energy operator method, Hilbert algorithm is large at low frequency; IEC analog flicker meter, digital flicker meter, instantaneous reactive power method, and D-q transformation method cannot perform time-frequency analysis on the flicker envelope, and cannot calculate the time of flicker occurrence and the frequency and amplitude of flicker voltage

Method used

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  • Voltage flicker measuring method for wind generating set
  • Voltage flicker measuring method for wind generating set
  • Voltage flicker measuring method for wind generating set

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0089] Example 1: Flicker caused by wind turbines

[0090] Set the simulation signal according to formula (20) or formula (21), and conduct a simulation analysis on the accuracy of the measurement results of flicker caused by the method proposed in this paper. The sampling rate f of the simulated signal in this example s 2000Hz

[0091] From 3s to 18s, three flicker changes with frequencies of 6Hz, 8.8Hz, and 12Hz occurred respectively. The relationship between the frequency, amplitude and time of the flicker voltage is as follows: Figure 3a and Figure 3b shown.

[0092] The standard parameters of S(t)=1 within 25Hz given by the IEC standard are selected to simulate and analyze the short-term severity of flicker caused by wind turbines. Based on the method proposed in this paper, the short-term flicker severity errors at different frequencies are as follows: Figure 3c shown.

[0093]

[0094]

[0095] In formula (20), A 0 is the fundamental wave voltage amplitu...

example 2

[0101] Example 2: Harmonics caused by wind turbines

[0102] In order to verify the accuracy of the method proposed in this paper to detect the harmonics caused by wind turbines, the harmonic signal is set according to formula (22). The sampling rate f of the simulated signal in this example s 4000Hz

[0103] Harmonics of different times are set to occur at different times. Since the energy of the fundamental wave is much greater than the energy of the harmonics, it is necessary to perform FFT filtering on the harmonic signals truncated by the 4 smallest sidelobe Nuttall windows to filter out the 50Hz fundamental wave. Then find out the frequency and amplitude of the harmonic through HHT. The harmonic measurement results of the simulation experiment are shown in Fig. 4. in Figure 4a is the relationship between time and frequency of the harmonic signal, Figure 4b is the relationship between the time and amplitude of the harmonic signal.

[0104]

[0105] In formula (...

example 3

[0107]Example 3: Voltage swell caused by wind turbines

[0108] Uncertainty of wind speed leads to unstable output current and power of grid-connected wind turbines, which causes voltage swell in grid voltage. The simulation signal is set according to formula (23), and the accuracy of the algorithm proposed in this paper to detect the voltage swell caused by the wind turbine is simulated and verified. The sampling rate f of the simulated signal in this example s 2000Hz

[0109] The grid voltage has two 5% voltage swells at different times. The measurement results of the voltage swell caused by the wind turbine are shown in Fig. 5. Figure 5a is the relationship between time and frequency, Figure 5b is the relationship between time and amplitude.

[0110]

[0111]

[0112]

[0113] In formula (23), f s = 2KHz; A 0 is the fundamental wave voltage amplitude of the power grid, is the initial phase angle, φ 0 =0; the simulation time is 10s.

[0114] It can be s...

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Abstract

The invention discloses a voltage flicker measuring method for a wind generating set, and relates to the technical field of electric energy quality measurement of the wind generating set. The method comprises the following steps that S1) the output end of the wind generating set is measured to obtain voltage and current time sequences; S2) voltage fluctuation is simulated in the virtual power grid; S3) an output signal of the virtual power grid is squared; S4) a Nuttall window function is used to cut the squared output signal; S5) filtering is carried out via FFT; S6) a flicker envelop signalwith the highest frequency is screened from signals only including the DC component and a low-frequency flicker envelop via empirical mode decomposition; S7) HHT transform is carried out on each IMF fluctuation signal; and S8) spectrum analysis is carried out on flicker voltages to obtain the short-time clicker server degree including frequency components. The method can be used to measure the short-time flicker server degree of the flicker voltage including multiple frequency components accurately.

Description

technical field [0001] The invention relates to the technical field of measuring the power quality of a wind power generating set, in particular to a method for measuring the voltage flicker of a wind generating set. Background technique [0002] In recent years, with the increasing consumption of fossil energy and the serious deterioration of the environment today, wind energy has been widely used as a clean energy source. research focus. [0003] With the rapid development of wind power generation, more and more high-power wind turbines are connected to the grid, which seriously reduces the power quality of the grid. As a result, the power quality problems of wind power and their solutions have gradually become a research hotspot. To improve the power quality of the power grid, it is first necessary to accurately detect and analyze the power quality, measure the power quality level of the power grid, analyze and judge the causes of various power quality problems, and pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R19/04G01R23/02G01R23/165
CPCG01R19/04G01R23/02G01R23/165
Inventor 孟克其劳王旭张占强
Owner INNER MONGOLIA UNIV OF TECH
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