An active power filter based on a nonlinear tracking differentiator and an arithmetic circuit thereof

Abstract

The invention discloses an active power filter based on a nonlinear tracking differentiator and an arithmetic circuit thereof. The filer comprises a voltage loop outputting the difference between themeasured actual value of a DC side voltage and a voltage reference value; a PI controller and a proportional integral controller are connected to the output of the voltage loop for outputting a corresponding reference current; a nonlinear differential tracker connected to the proportional integral controller and capable of more rapidly tracking a reference current and the derivative signal, and filtering the harmonics in the reference current; a phase-locked loop generating a unit sinusoidal voltage signal in the same phase and same frequency with a grid side voltage and detecting the voltagephase on the grid side; and a multiplier connecting with the outputs of the nonlinear tracking differentiator and the phase locked loop to obtain a reference value of the current on the grid side . According to the invention, the dynamic performance of the active power filter is greatly improved under the premise of shortening the reaction time, and the reference current can maximize the suppression of harmonics.

Description

technical field [0001] The invention relates to the electronic field, in particular to an active power filter based on a nonlinear tracking differentiator and an operation circuit thereof. Background technique [0002] The active power filter is a power electronic device for real-time compensation of reactive power and suppression of harmonic currents. It can perform real-time compensation for harmonics with varying frequency and size and varying reactive power, which can overcome traditional filters Disadvantages of equal harmonic suppression and reactive power compensation methods. The control method based on harmonic current detection and the double closed-loop control method are the main two control methods. The basic principle of the control method based on harmonic current detection is to first detect the harmonic and reactive components in the load current, and offset them by outputting a compensation current of equal magnitude and opposite direction through the conv...

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Problems solved by technology

[0003] However, this method needs to detect load current, compensation current and grid voltage, etc., and requires more complicated mathematical formulas and algorithms to process the load current to extract harmonics and reactive components. The hardware needs greater support, such as More advanced processing chips, etc., equipment costs are relatively large

In contrast, the double closed-loop control method only needs to detect the voltage and current on the grid side, and does not need to detect the load current and compensation current, and does not need to extract harmonics and reactive power. The algorithm is simple, easy to implement, and more economical and reliable. The control method usually uses a proportional-integral controller to adjust the output current in real time, but we can understand that the output signal of this controller contains harmonic signals, which cannot achieve the desired effect.

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