Parallel active power filter direct current side voltage low-frequency ripple suppression method

Abstract

The invention discloses a parallel active power filter direct current side voltage low-frequency ripple suppression method, and belongs to the field of power electronic control. The method comprises the following steps of 1, connecting a direct current side split capacitor active power decoupling circuit in parallel on the direct current side of a traditional parallel active power filter; and 2, by controlling the active power decoupling circuit, transferring the low-frequency fluctuation power of the direct-current side of the active power filter to an auxiliary capacitor, and realizing low-frequency ripple suppression of the voltage of the direct-current side of the active power filter. Based on an active power decoupling technology, 6-frequency-multiplication, 12-frequency-multiplication, 18-frequency-multiplication and 24-frequency-multiplication fluctuation of the direct-current side voltage of the parallel active power filter is suppressed, a thin-film capacitor with a small capacitance value can be used for replacing a traditional electrolytic capacitor under the condition that the direct-current side voltage fluctuation is small, and the reliability of a system is improved. In addition, a low-pass filter in a direct-current side voltage control link of the active power filter is omitted, and the corresponding speed of the system is increased.

Description

Technical field [0001] The present invention relates to the field of power electronics control, and more particularly to a parallel active power filter DC side voltage low frequency ribbal wave suppression method. Background technique [0002] Active power filter balances fast harmonic compensation and reactive compensation function, is an important device in power quality management, which can be compensated for harmonics caused by nonlinear loads such as various rectifiers, inverters, and improve power quality. . Among them, the Shunt Active Power Filter, SAPF) is easy to perform the operation of the grid, and is currently widely used in the power system during the failure. [0003] The load harmonics in the three-phase opposite grid mainly include 6k + 1 (k = 1, 2, ... (natural number)) secondary sequence harmonics and 6K + 5 (k = 0, 1, ... (natural number)) subordination Harmonics, SAPF will cause its direct side voltage to be 6K (k = 1, 2, ... (natural number)) times when co...

AI Technical Summary

Problems solved by technology

The amplitude of the voltage fluctuation on the DC side greatly affects the quality of the SAPF output current. In order to suppress the voltage fluctuation on the DC side, the traditional method is to connect a large-capacity electrolytic capacitor in parallel on the DC side of the SAPF to slow down the fluctuation, but there is an electrolyte in the electrolytic capacitor. Volatility and short life, especially when the fluctuating voltage is large, the fluctuating current repeatedly charges and discharges the electrolytic capacitor, which accelerates the aging of the capacitor and requires frequent replacement of the electrolytic capacitor, which affects the reliability of the device. At the same time, the large capacity The value of the electrolytic capacitor greatly affects the response speed of the DC side voltage

In addition, in order to avoid the impact of the fluctuation voltage on the DC side on the output current of the SAPF, a low-pass filter with a very low cut-off frequency needs to be added, which further reduces the response speed of the system

[0004] At present, a small number of scholars have suppressed the fluctuation of the SAPF DC side voltage by introducing a resonant controller, but the effect is very small, and it will also have a certain impact on the output current of the SAPF.

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