Series hybrid active electric filter device

Abstract

The invention discloses a serial hybrid active power filter device, which comprises a harmonic current detection unit, a harmonic current compensation and generation unit, a serial transformer and a passive filter. The serial transformer has a small self-inductance per-unit value of 0.1 to 10%. S identical harmonic currents generated by the harmonic current compensation and generation unit are injected to S identical secondary windings of the transformer. The harmonic current is identical to the harmonic current at the primary side and has a magnitude of (a*k) / S times the harmonic current at the primary side, so that the serial transformer has smaller self induction L1 relative to the fundamental wave and larger self induction L1 plus aM relative to the harmonic current so as to make the harmonic current flow to the passive filter. If a fault occurs on the active section, the active section is switched off by a switch to prevent from influencing the power supply on loads. Due to the open access of the serial transformer, the system impedance is increased by 0.1 to 10% and still has filter effect. The device has the advantages of no need for LC functional wave resonant circuit, small capacity of the secondary side of the active section and the serial transformer, and good filter effect, and reduces the cost.

Description

A series hybrid active power filter device technical field The invention belongs to the technical field of power filtering, and in particular relates to a series hybrid active power filtering device using a low self-inductance series transformer. Background technique The series hybrid filter is a combined power filter that uses series active and parallel passive. It can better overcome the resonance problem when the passive filter is used alone, and significantly improve the filtering effect of the passive filter. Moreover, the capacity of the active part is small, the cost performance is high, and it has a good application prospect. So far, the series hybrid active power filter mainly has the following schemes: Scheme 1 (PengFangZheng; AkagiHirofumi; SabaeAkira, A new approach to harmonic compensation in power systems--A combined system of shunt passive and series active filters, IEEE Transactions on Industry Applications, vol.26, no.6, Nov-Dec, 1990, page983-990) propo...

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Problems solved by technology

If the active part fails or needs to be repaired and out of operation, the load will be powered off in the above three schemes, so the power supply reliability is poor

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