An active power filter based on multi-phase variable flow structure

Abstract

The invention discloses an active power filter based on a multiphase converter structure. The active power filter comprises a multiphase converter, a multiphase filter, a controller and a multiphase transformer. By adopting a multiphase compensation current generation device and a multiphase-to-three-phase converter structure and by using the characteristic that a multiphase PWM (pulse width modulation) converter has a plurality of control freedom degrees, the active power filter realizes low-voltage high power and is easier to realize on the premise that the direct serial and parallel connection of electronic power devices is avoided; compared with the existing multilevel active power filters, the structure of the active power filter is simple, the overall control is facilitated, the goal of perfect uniform coordinated output is realized and the energy density is high; since the converter adopts low-voltage power devices, the cost is reduced, the goal of fault-tolerant control is easy to realize, the corresponding phase is only required to be cut off when one phase or several phases have a fault, the overall output of a system is not influenced and the reliability is higher; and by changing the structure of the multiphase converter, the active power filter is also suitable for independent power supply systems of ships and the like, and the application scope is wide.

Description

technical field [0001] The invention belongs to the technical field of harmonic compensation, and in particular relates to an active power filter based on a multi-phase variable flow structure. Background technique [0002] In recent years, the use of a large number of nonlinear loads has made the problems of harmonic pollution and power factor degradation increasingly prominent. The effective control of harmonics is of great significance to power systems and power users. For high-voltage and large-capacity harmonic sources, the filtering performance of the LC passive filter (PF) currently used in the market is extremely sensitive to changes in system impedance, frequency and other parameters, and its dynamic performance is poor, making it difficult to achieve the expected filtering effect. The active power filter (Active Power Filter, APF) can dynamically compensate the harmonics and reactive power that change in frequency and amplitude, damp the local grid resonance, reduc...

AI Technical Summary

Problems solved by technology

[0004] In the traditional active power filter, the two-level active power filter can no longer meet the requirements of high power and high frequency; considering the capacity limitation of power semiconductor devices, at this stage, multi-level active power filters are mostly used in the field of high voltage and high power Active Power Filter

Multi-level active power filter Each power device withstands The DC bus voltage (n is the number of levels) can achieve high voltage and high power with low withstand voltage devices. The flat PWM converter has n 3 The switching variable, the difficulty of control is greatly increased; in addition, because the multi-level converter uses multiple power devices, the system is expensive and the reliability is low, and a device failure of the high-voltage multi-level three-phase active power filter system can render the entire system inoperable

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