Wide-range frequency self-adaptive control method based on current type grid-connected system

A technology of frequency self-adaptation and control method, applied in AC network to reduce harmonics/ripples, electrical components, circuit devices, etc., can solve the problems of control system performance degradation, complex control, increase of program memory, etc., to achieve Frequency self-adaptation, solving the output current oscillation, and improving the effect of precision

Active Publication Date: 2020-10-16
SHIJIAZHUANG TONHE ELECTRONICS TECH CO LTD
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  • Application Information

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Problems solved by technology

[0003] Single-phase grid-connected inverters use the current loop control method. Scholars at home and abroad have conducted in-depth research on the sudden change of grid frequency. However, under normal circumstances, the grid frequency changes between 49.5HZ-50.5HZ, and it is kept between 45HZ-55HZ. Wide range of grid frequency variations between, few people involved in
[0004] Most scholars use repetitive control to adapt to the frequency of the power grid. For example, in 2020, Li Weifeng and others published in "Power System Protection and Control": "New Frequency Adaptive Compound Repetitive Control and Grid-connected Inverter Application" and 2017 The “New Frequency Adaptive Repetitive Control Method for LCL Grid-connected Inverters” published by Chen Lei et al. used repetitive control, but this method usual

Method used

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  • Wide-range frequency self-adaptive control method based on current type grid-connected system
  • Wide-range frequency self-adaptive control method based on current type grid-connected system
  • Wide-range frequency self-adaptive control method based on current type grid-connected system

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Embodiment Construction

[0068] The technical solutions of the present invention will be further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0069] In the experiment, the system uses a rated voltage amplitude of 220V, a frequency of 45Hz-55Hz, and the grid introduces harmonics. Under this condition, when the grid frequency is 50Hz, the output waveform of the all-pass filter is as follows: Figure 11 As shown, it is obvious that the use of all-pass filter has a general suppression effect on grid harmonics.

[0070] In the case of 50Hz, change the parameters of the second-order low-pass filter from fixed values ​​to fitting curves, and output current waveforms, such as Figure 12 As shown, it can be seen that due to the limitation of curve fitting accuracy, the fitting parameters are not completely consistent with the actual parameters in the case of 50Hz, resulting in output distortion. In the same state, experiment at 45Hz and 55Hz, the experi...

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Abstract

The invention discloses a wide-range frequency adaptive control method based on a current type grid-connected system. When an inverter is in grid-connected operation, because the frequency of the power grid changes suddenly, the output of the inverter is distorted, harmonic distortion occurs, and then current oscillation occurs. In this case, the instability of the system has a great influence onelectric equipment and an inverter module. To meet market requirements, according to the method, the power grid frequency is suddenly changed in a wider range (45Hz-55Hz), the inverter system has goodstability, and a wide-range frequency adaptive control strategy is provided on the premise of considering the sudden change of the power grid frequency, so that the stable operation of the system isrealized.

Description

technical field [0001] The invention belongs to the field of electrical control, in particular to a wide-range frequency self-adaptive control method based on a current-type grid-connected system. Background technique [0002] With the depletion of traditional fossil energy, new energy power generation systems such as photovoltaic power generation and wind power generation have sprung up, becoming a research hotspot in recent years. New energy power generation systems usually realize grid-connected operation through the inverter interface. In order to improve the current quality of the inverter grid-connected current and system stability, it is important to rationally design the control scheme of the inverter system according to different grid states and sudden changes in grid frequency. significance. [0003] Single-phase grid-connected inverters use the current loop control method. Scholars at home and abroad have conducted in-depth research on the sudden change of grid f...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02J3/24H02J3/01
CPCH02J3/38H02J3/241H02J3/01H02J2203/20H02J2300/22H02J2300/28Y02E40/40
Inventor 马群曹会平张浩赵子龙逯曼吴彦
Owner SHIJIAZHUANG TONHE ELECTRONICS TECH CO LTD
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