Control method for predicating switching signal of three-phase four-wire active filter

Abstract

The invention discloses a control method for predicating a switching signal of a three-phase four-wire active filter, comprising the following steps of: step 1: acquiring a signal, and computing a reference current signal Iref, wherein the computing formula of the reference current signal is that Iref=Ipref*sin omega t+Idc-pref / 3+Ih; step 2: computing the switching time T of the next time; T=(Us+L1*(Iref-Iinv-Ic1-Ic2) / T +L2*(Iref-I-Ic1) / T) / U, or computing by the formula T=-(Us+L1*(Iref-Iinv-Ic1-Ic2) / T +L2*(Iref-I-Ic1) / T) / U; and step 3: controlling a switching device of each phase in a three-level inverter bridge according to the T. The control method for predicating the switching signal of the three-phase four-wire active filter is used for predicating the switching state of the next control period according to the single-phase status of the active filter, thereby being easy to implement, and quick in response speed.

Description

technical field [0001] The invention belongs to the active filter technology, and relates to a three-phase four-wire active filter switch signal predictive control method. Background technique [0002] With the popularization of household electronic equipment, the power quality of distribution network is seriously affected. In particular, household electrical equipment widely uses rectifiers for power supply, which brings a lot of harmonic pollution to distribution network and must be treated. The treatment of harmonics mainly includes passive filters, active filters and hybrid filters. Parallel passive filter is the simplest harmonic control method, but it can only have a good filtering effect on specific harmonics, and the filtering frequency band is very narrow. Passive filter is a power electronic device that can compensate harmonics of any frequency and size. The compensation characteristics are not affected by grid impedance and frequency changes. It is an ideal harmo...

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Problems solved by technology

[0004] For the three-phase four-wire active power filter of the distribution network, since the harmonic frequency band to be controlled is very wide (generally from the 2nd harmonic to the 50th harmonic), it must be ensured that the controller has a large frequency range in the wide frequency range. Gain, the traditional PI control is difficult to meet

For this reason, the 2nd to 50th harmonics must be detected separately, and then a controller is designed for each harmonic separately, which makes the controller very complicated and it is difficult to guarantee the response speed of the system. compensation, the three phases must be controlled separately, which further increases the burden on the controller

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