An Active Power Filter

Abstract

The invention discloses an active electrical filter, wherein the active electrical filter of a single phase system comprises a harmonic wave voltage detection unit, a control unit, a series connection transformer unit and a passive filter unit. The harmonic wave voltage detection unit comprises a voltage transformer and a harmonic wave voltage detection device; the control unit comprises a voltage gain circuit and a voltage generation circuit, wherein the voltage transformer is in parallel connection with the first side of the series connection transformer unit, and is in connection with the harmonic wave voltage detection device; the harmonic wave voltage detection device is in connection with the voltage gain circuit; the voltage gain circuit is in connection with the voltage generation circuit; the voltage generation circuit is in connection with the secondary side of the series connection transformer unit; the first side of the series connection transformer unit is in series connection between an access grid and a harmonic wave source load; the passive filter unit is in parallel connection with two ends of the harmonic wave source load. The active electrical filter has the characteristics of smaller inversion amount, simple structure and control, and good filtering effects, and is convenient to realize.

Description

technical field [0001] The invention relates to the technical field of power filters, in particular to a series hybrid active power filter. Background technique [0002] The wide application of power electronic devices and non-linear loads generates a large number of harmonics, which degrades the power supply quality of the power system. Harmonics is a kind of pollution and a public nuisance to the power system. It not only poses a threat to the safe and economic operation of the power system itself, but also brings great influence and harm to the surrounding electrical environment. Various advanced precision instruments and equipment in the fields of modern information technology, microelectronics technology and numerical control processing technology have higher and higher requirements for power supply quality, and harmonic suppression has become a hot issue concerned by power systems and power users. [0003] Power electronic conversion devices are the most important sou...

AI Technical Summary

Problems solved by technology

[0003] Power electronic conversion devices are the most important source of harmonics in the power system at present. There are two solutions to solve the harmonic problems caused by power electronic devices: one is the active solution, that is, to transform the power electronic devices themselves so that they do not generate Harmonic, this kind of device belongs to the green power electronic device, which is a popular research direction in the field of power electronics. The main disadvantage of this scheme is that the power electronic device must bear all the power, the system dynamic response is very high, and the existing equipment It is expensive to update; the other is a passive solution, which compensates harmonics by installing a harmonic compensation device, which is commonly referred to as a power filter. In addition to filtering functions, most power filters also have Function of static or dynamic var compensation

Power filters are generally divided into passive power filters and active power filters, among which passive power filters are currently the most widely used and mature means of harmonic suppression, but passive power filters have some inherent disadvantages: it may cause Resonance phenomenon, the impedance of the system seriously affects the filter characteristics, and it is impossible to compensate the changing harmonics in real time, etc.

The unified power quality controller consists of two inverters, one is connected in series in the system, mainly for harmonic isolation, voltage regulation and compensation for flicker and unbalanced voltage; the other is connected in parallel at both ends of the harmonic source, mainly for compensation Harmonic current or negative sequence current and the role of regulating the DC bus voltage of the two inverters, the disadvantage of this system is that the structure and control are very complicated

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