Method, device and system for modulating zero sequence voltage pulse width of three-phase four-legged APF (active power filter)

Abstract

The invention provides a method, a device and a system for modulating a zero sequence voltage pulse width of a three-phase four-legged APF (active power filter). The method comprises the following steps of solving a zero sequence component according to a reference value of a voltage of midpoints of legs A, B and C of the three-phase four-legged arm APF to a midpoint of a leg N of the three-phase four-legged arm APF; controlling a pulse duty ratio according to a reference value of a voltage of a calculating point N of the three-phase four-legged APF to a point O of a cathode of a direct-current bus capacitor and a switch tube of the leg N; and solving a voltage of the midpoints of the legs A, B and C of the three-phase four-legged APF to the point O of the cathode of the direct-current bus capacitor and a corresponding duty ratio. A zero sequence voltage linear control pulse width modulation strategy is applied to the three-phase four-legged APF. Compared with the traditional 3D-SVPWM (three-dimensional space vector pulse width modulation) strategy, the zero sequence voltage linear control pulse width modulation strategy is easy to implement and can reduce calculation delay and requirements on main frequency; and the response speed of the three-phase four-legged APF can be increased further, the harmonic compensation accuracy of the three-phase four-legged APF can be improved, hardware investment is saved, and the method has an important practical significance on practical degree of a project of the three-phase four-legged APF.

Description

technical field [0001] The invention relates to the technical field of pulse width modulation strategies of three-phase four-arm active power filters, in particular to a zero-sequence voltage linear control pulse width modulation technical scheme of three-phase four-arm active power filters. Background technique [0002] With the increasing application of various power electronic devices, the voltage and current waveforms of the distribution network are seriously distorted, which affects the safe and stable operation of the system. In my country, the 380V low-voltage distribution network is powered by a three-phase four-wire system, and the three-phase four-arm active power filter (Acitve Power Filter, APF) is used to control the harmonics and neutral in the three-phase four-wire distribution network. One of the most effective means of excessive line current. APF can track and compensate the harmonics whose frequency and amplitude change, and the compensation characteristics...

AI Technical Summary

Problems solved by technology

[0004] The present invention proposes a pulse width modulation strategy using the zero-sequence component of the APF output voltage reference value to perform linear control of the switching tube control pulse duty ratio, and solves the problem that the traditional 3D-SVPWM strategy has a complex implementation process and a large calculation delay leading to poor compensation effects question

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