H-bridge cascade type active power filter

Abstract

The invention relates to an H-bridge cascade type active power filter. In the invention, an A phase valve circuit LINKA, a B phase valve circuit LINKB, a C phase valve circuit LINKC and a passive filtering inductor branch are connected in a star shape or a triangular shape and then are merged in a power grid. The valve circuit of each phase comprises a common alternating-current bus, a single-phase transformer bank, a direct-current isolation capacitor, an inductor series circuit group, a single-phase H-bridge auxiliary transformer bank, a direct-current voltage support unit direct-current capacitor group and a single-phase H-bridge main convertor group; the single-phase transformer bank comprises m single-phase transformers, and primary windings are connected in parallel through the common alternating-current bus; n secondary windings of the m single-phase transformers are connected with n single-phase H-bridge auxiliary converters through an inductor and the direct-current isolation capacitor group; the n single-phase H-bridge auxiliary converters are respectively connected with n single-phase H-bridge main transformer direct-current voltage support capacitors; and n single-phase H-bridge main converters are connected with the power grid in parallel through the passive filtering inductor branch after being cascaded.

Description

technical field [0001] The invention relates to an active power filter, in particular to an H-bridge cascaded active power filter suitable for large-capacity reactive power compensation and harmonic suppression. Background technique [0002] With the development of power electronics technology, various nonlinear power electronic devices have been widely used in power systems, industries (especially metallurgy, steel, chemical industry, etc.), transportation, building automation and households, and their device capacity is increasing The large and diversified control methods make the voltage and current waveform distortion in the power grid more and more serious, and the harmonic pollution in the power grid is becoming more and more serious. In order to overcome the shortcomings of passive power filter (PPF), an important trend of harmonic suppression devices is to use active power filter (APF) to meet the harmonic standards IEEE519-1992, Requirements of GB / T14549-93 "Power ...

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Problems solved by technology

For APF, its compensation current is a harmonic current, which requires a high switching frequency, a large change in the pulse width of each H-bridge, and requires rapid capacitor voltage balance. The need for harmonic governance

Chinese patent 03142679.4 also performs balance control on the DC side capacitor voltage of the H-bridge cascaded multi-level inverter, and enables active power exchange between the H-bridge cascaded power units through additional external equipment, thereby realizing balanced control of the capacitor voltage , but it uses more power switching devices, which increases system cost and control complexity

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