Active power filter and control method therefor

Abstract

The invention discloses an active power filter and a control method therefor. A power filter of a single phase system comprises a current detection unit, a control unit, a series transformer unit and a passive filter unit, wherein the current detection unit detects a primary side current of the series transformer unit and outputs the primary side current to the control unit; the control unit receives the primary side current, extracts a fundamental component and a harmonic component of the primary side current, and converts the fundamental component and the harmonic component into a current fundamental instruction signal obtained by inverting the fundamental component and a current harmonic component instruction signal obtained by multiplying the harmonic component by a multiple K respectively; the control unit generates corresponding currents proportional to the current fundamental instruction signal and the current harmonic component instruction signal, and outputs the currents to a secondary side of the series transformer unit; and the passive filter unit receives a harmonic current of a harmonic source load. According to the active power filter and the control method therefor, no passive branches are required, so that the problem of reduced harmonic equivalent impedance caused by harmonic voltage interference is improved and a better filtering effect is achieved.

Description

technical field [0001] The invention relates to the technical field of power filters, in particular to a series hybrid active power filter and a control method thereof. Background technique [0002] The wide application of power electronic devices and nonlinear loads generates a large number of harmonics, which degrades the power supply quality of the power system. There are two existing solutions to harmonic problems: one is an active solution, that is, to modify the power electronic device itself so that it does not generate harmonics; the other is a passive solution, by installing a harmonic compensation device To compensate harmonics, this is commonly referred to as a power filter. Power filters are generally divided into passive power filters and active power filters. Among them, passive power filters are currently the most widely used and mature harmonic suppression However, passive power filters have some inherent disadvantages: it may cause resonance, the impedance ...

AI Technical Summary

Problems solved by technology

There are two existing solutions to harmonic problems: one is an active solution, that is, to modify the power electronic device itself so that it does not generate harmonics; the other is a passive solution, by installing a harmonic compensation device To compensate harmonics, this is commonly referred to as a power filter. Power filters are generally divided into passive power filters and active power filters. Among them, passive power filters are currently the most widely used and mature harmonic suppression means, but passive power filters have some inherent disadvantages: it may cause resonance, the impedance of the system seriously affects the filtering characteristics, and it is impossible to compensate the changing harmonics in real time, etc.

[0003] Among these active power filters, the series hybrid active power filter uses a combination of a parallel passive filter and a smaller-capacity active power filter to complete the large-capacity filtering task, which can reduce costs and has a high cost performance , so it is widely used, but the existing series hybrid active power filter has many passive branches, and is easily affected by harmonic interference voltage, which greatly reduces the filtering effect of the filter

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