Harmonic degradation analysis method for parameter-unknown grid-connected inverter based on impedance fitting

An analysis method and inverter technology, applied in complex mathematical operations, design optimization/simulation, special data processing applications, etc., can solve problems such as there is no very effective method, reduce the number of iterations, and meet fast and accurate impedance modeling The effect of shortening the time-consuming calculation

Active Publication Date: 2021-05-25
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Abstract
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Problems solved by technology

There are a large number of commercial grid-connected inverters whose internal information is kept secret in the a

Method used

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  • Harmonic degradation analysis method for parameter-unknown grid-connected inverter based on impedance fitting
  • Harmonic degradation analysis method for parameter-unknown grid-connected inverter based on impedance fitting
  • Harmonic degradation analysis method for parameter-unknown grid-connected inverter based on impedance fitting

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Embodiment 2

[0080] Based on RT-LAB, a semi-physical real-time simulation platform was built, and the following experiments were carried out: Example 1: The power grid is in a state of no background harmonics, and the grid-connected current waveform of the inverter at the PCC point is observed, as shown in Figure 5(a); Carry out FFT decomposition, and draw the frequency spectrum as shown in Fig. 5(b). Embodiment 2: There are 14 background harmonics in the grid voltage, and the harmonic amplitude is 5% of the rated voltage. Observe the grid-connected current waveform of the inverter at the PCC point, as shown in Figure 5(c); perform FFT on it Decompose and draw the spectrogram as shown in Figure 5(d).

[0081] When there is no background harmonic in the power grid, it can be seen from Figure 5(a): the grid-connected inverter grid-connected current waveform has no obvious distortion; it can be seen from Figure 5(b) that the grid-connected inverter will Inject wide-frequency domain harmonic ...

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Abstract

The invention discloses a harmonic degradation analysis method for a parameter-unknown grid-connected inverter based on impedance fitting, and the method comprises the following steps: S1, collecting frequency response data of the grid-connected inverter, converting the frequency response data into time domain data, and calculating an initial order and an initial pole through a matrix pencil algorithm; S2, updating a pole, estimating a residue, a first term and a constant term by using vector matching, and performing impedance fitting to obtain a frequency response fitting value; S3, calculating the relative error percentage of the frequency response fitting value and the actually measured frequency response data, comparing the relative error percentage with a given threshold value, if the relative error percentage is greater than the given threshold value, updating the initial parameter, repeating S2 to form iteration until the relative error percentage is less than the given threshold value, and outputting an impedance fitting result; and S4, based on a fitting result, searching a harmonic resonance point through an impedance analysis method. According to the method, impedance fitting is carried out on the grid-connected inverter with an unknown structure, parameters and a control mode based on frequency response data, the time consumption of iterative calculation is short, and the precision of a fitting result is high.

Description

technical field [0001] The present invention relates to the technical fields of cloud computing and collaborative rendering, in particular to a harmonic degradation analysis method for grid-connected inverters with unknown parameters based on impedance fitting. Background technique [0002] Grid-connected inverters with multiple types and multiple working conditions are more and more widely used in power electronic new energy power systems. Affected by the impedance characteristics of the network, the harmonics in the grid-connected current of the grid-connected inverter may be amplified by the excitation of the background harmonic voltage in the grid, resulting in harmonic degradation and reducing the grid-connected power quality of the grid-connected inverter , affecting the stability of the power system operation. The key to harmonic degradation analysis of grid-connected inverters is impedance modeling. However, the current inventive methods all require that internal in...

Claims

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Application Information

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IPC IPC(8): G06F30/20G06F17/16G06F17/12
CPCG06F30/20G06F17/16G06F17/12Y02E40/40
Inventor 李建文吴滨源马小棠王月杨夷南
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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