Active filter control method based on harmonic voltage selection compensation

Abstract

The invention discloses an active filter control method based on harmonic voltage selection compensation. According to the method, by introducing a base wave and step factors in sub-harmonic wave self-adaption filtering link, the weight coefficient of sub-voltage component is rapidly and accurately calculated through recursive iteration, and the defects that according to traditional sliding Fourier transform, the calculated amount is large and the resource consumption is large are overcome. The method includes the steps of achieving sub-harmonic voltage selection compensation by reconstituting sub-harmonic components, and adjusting sub-harmonic wave conductance gains through the self-adaption algorithm according to the magnitude of the sub-harmonic wave containing ratio. The method is not influenced by the route parameter uncertainty or the time-varying characteristics, and the defect of fixed gains is overcome. According to the active filter control method, when distortion of the system voltage is serious and the system runs in an asymmetrical mode, sub-harmonic wave voltage components can be accurately extracted, self-adaption adjustment of the conductance gains can be accurately conducted, the stability is high, and the tracing speed is high.

Description

technical field [0001] The invention belongs to the technical field of power system harmonic control, and relates to a control method for an active filter to suppress harmonic voltage amplification, and in particular to an active filter control method based on harmonic voltage selective compensation. Background technique [0002] In order to compensate reactive power and improve power factor, large power factor correction capacitors are usually connected in parallel in substations and factories, and there is line equivalent inductance on the system transmission line. Due to the existence of background harmonics, capacitors and line inductance may form a series-parallel connection A resonant circuit causes harmonics of a certain frequency to resonate and propagate on the transmission line. Whether it is series resonance or parallel resonance, it will lead to severe distortion of the grid voltage, which not only reduces the power supply quality of the power system, but also is...

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Problems solved by technology

However, there are few researches on the control method of active filter based on harmonic damping at present, and the harmonic voltage damping is carried out under the condition of knowing the harmonic distribution of the background harmonic voltage. The control method is relatively simple and cannot satisfy the harmonic When the voltage distribution frequency is wide and the degree of distortion is large, the usual method is to collect the three-phase voltage of the APF installation point, transform it into the dq coordinate system through the park, and then obtain the voltage harmonic component through a high-pass filter, multiply it by the conductance gain K Get the reference value of APF compensation current, but Keiji Wada passed in "Considerations of a Shunt Active Filter Based on Voltage Detection for Installation on a Long Distribution Feeder, IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL.38, NO.4, JULY / AUGUST2002" Calculate the impedance of the line to derive the conductance gain K. This method can achieve a good harmonic damping effect when the system background harmonics and line parameters are known.

Its shortcoming is that this method is affected by the uncertainty and time-varying nature of line parameters, and it is difficult to obtain the conductance gain K through calculation. Therefore, this method is difficult to implement in practical applications, which may lead to the reduction of voltage harmonics at the installation point. Harmonic amplification at the installation point of APF is difficult to apply to occasions where the order of harmonic voltage is uncertain and the response speed is high

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