Adaptive network voltage feed-forward compensation method for grid-connected inverter

Abstract

The invention discloses an adaptive network voltage feed-forward compensation method for a grid-connected inverter and belongs to the field of current control of the grid-connected inverter (including an inverter and a rectifier). The method comprises the following steps that the network voltage of a point of common coupling is sampled and the voltage is taken as an input signal for adaptive network voltage feed-forward compensation of the grid-connected inverter, the input signal generates one group of output signals through one group of parallel band-pass filters at the harmonic frequency, and independent output signals in the group of output signals are added to generate a voltage signal used for feed-forward compensation; and meanwhile, resonance detection is carried out on the independent output signals, and when the amplitude of one output signal is suddenly increased, the related output signal is eliminated from the voltage signal used for feed-forward compensation according to the adaptive logic. The method has the advantages of strong adaptability for large-range varying network impedance, excellent grid-side current quality and convenience for design.

Description

technical field [0001] The invention relates to a grid-connected converter adaptive grid voltage feed-forward compensation method, which belongs to the field of current control of grid-connected converters (including inverters and rectifiers). Background technique [0002] With the vigorous development of new energy distributed grid-connected power generation, grid-connected converters, as a key part of them, have gained widespread attention. However, converters using pulse width modulation technology generate a large number of switching frequency sub-harmonics. Inserting a filter between the converter and the grid can effectively suppress harmonics. Commonly used filters include L and LCL filters. In order to achieve higher grid-connected power factor and lower grid-side current harmonic distortion, scholars have proposed a large number of grid-connected converter control methods. However, the existing relatively mature control methods only consider the ideal grid. Unce...

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Problems solved by technology

This method solves the instability problem of the grid-connected converter under the weak grid, but this method sacrifices the ability of the PCC voltage feed-forward compensation to suppress the grid-side current harmonics, which is not conducive to improving the grid-side of the grid-connected converter under the weak grid. current quality

[0004] Based on the above analysis, PCC voltage feed-forward compensation can better suppress the grid-side current harmonics caused by grid voltage distortion, but in weak grids, feed-forward compensation can easily lead to poor system stability and serious grid-side current harmonic distortion.

The existing typical feed-forward compensation method is difficult to take into account the stability of the grid-connected converter and the quality of the grid-side current in a weak grid

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