A Control Method for Compensating the Neutral Line Current of Distribution Network by Three-level Four-leg Active Filter

Abstract

The invention provides a three-level four-leg active filter compensation distribution network neutral current control method. The method includes the steps of extracting harmonic waves and the sum of negative sequence components and zero sequence components of a line current as a command current of the controlling; setting the alternating current side three-phase current of an active filter and a neutral current as feedback currents, and performing feedforward decoupling control and dq0-abc conversion on each current component of dq0 axis for outputting three-phase voltage after respectively performing abc-dq0 conversion on the command current and the feedback currents; separately performing compensation control on the neutral current. The purpose of direct current side voltage balance and stability can be achieved through direct current side voltage stability and balance control. The three-level four-leg active filter compensation distribution network neutral current control method can effectively solve the problems such as overcurrent of a neutral line due to load imbalance in a three-phase four-wire system and is quick in response of a control system, capable of achieving dynamic real-time compensation and good in control effects.

Description

technical field [0001] The invention relates to a control method, in particular to a control method for compensating the neutral wire current of a distribution network by a three-level four-bridge arm active filter. Background technique [0002] In China's low-voltage distribution network, most of the power is supplied to users with a three-phase four-wire system. If the high-power single-phase load is unbalanced connected to the three-phase grid or the power consumption of the single-phase load is not synchronized, these will lead to three-phase faults in the distribution network. unbalanced. At the same time, it will also bring a series of hazards, for example, the excessive current of the neutral line will cause the line to burn out, the generated zero-sequence current will cause losses to the transformer, and the power supply quality problems such as three-phase voltage asymmetry. [0003] To solve the above-mentioned problems such as excessive neutral line current caus...

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Problems solved by technology

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a control method for compensating the neutral line current of the distribution network with a three-level four-arm active filter, which can effectively solve the problem caused by the unbalanced load in the three-phase four-wire system Neutral line overcurrent and other problems, the control system responds quickly, can realize dynamic real-time compensation, and the control effect is excellent

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