Active filtering circuit for preventing harmonic of 400V power distribution system in plant

Abstract

The invention provides an active filtering circuit for preventing harmonic of a 400V power distribution system in a plant. The active filtering circuit comprises a slow starting circuit, a filtering circuit and an inversion circuit, wherein the slow starting circuit is connected with an A phase, a B phase and a C phase of a three-phase power supply, a rear end of the slow starting circuit is connected with the filtering circuit, a negative electrode of the filtering circuit is connected with a null line pole N of the three-phase power supply, the inversion circuit is connected in parallel withthe filtering circuit by a reactor, and a rear end of the inversion circuit is connected with an energy storage circuit and then is connected with the null line pole N of the power supply. By the active filtering circuit, each harmonic can be compensated, flickering can be prevented, reactive power can be compensated, various functions by a machine are achieved, the active filtering circuit is relatively reasonable in cost performance, the filtering characteristic is free from the influence such as system impedance, the risk of resonance with the system impedance can be eliminated, the activefiltering circuit has an adaptive function, the changing harmonic can be automatically traced, and the active filtering circuit has the characteristics of high controllability, rapid response and thelike.

Description

Technical field [0001] The invention relates to a harmonic active filter circuit for suppressing a factory 400V power distribution system. Background technique [0002] In the power distribution system of modern enterprise factories, due to the wide application of high-power semiconductor converter equipment and electronic voltage regulating devices, such as frequency converters, central air conditioners, etc., these nonlinear loads bring non-sinusoidal currents to the power system, causing a lot of The injection of power harmonics has caused the quality of the power supply of the power system to decline, and the serious harmonic pollution in the low-voltage power grid has increased the power loss and caused great safety risks. The current electricity consumption problems of enterprises are mainly manifested in the following aspects: 1. Harmonic current is superimposed on the fundamental wave of the capacitor, resulting in resonance, which will increase the capacitor current, inc...

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Problems solved by technology

[0002] In the power distribution system of modern enterprise factories, due to the wide application of high-power semiconductor converter equipment and electronic voltage regulation devices, such as frequency converters, central air conditioners, etc., these nonlinear loads bring non-sinusoidal currents to the power system, causing a large number of The injection of power harmonics causes the power supply quality of the power system to decline, and the serious harmonic pollution in the low-voltage power grid increases power loss and causes great safety hazards

The current power consumption problems of enterprises are mainly manifested in the following aspects: 1. The harmonic current is superimposed on the fundamental wave of the capacitor, resulting in resonance, which will increase the current of the capacitor, increase the temperature, shorten the service life, and affect the normal and safe use of electricity. The long-term impact of wave current on the capacitor may cause the capacitor cabinet to burn out, and even more serious electricity safety accidents; 2. Distorted power increases the copper loss and iron loss of the transformer, reducing the capacity of the transformer; 3. The transformer overheats and generates large Noise, under the impact of harmonic current for a long time, will reduce the service life of the transformer, and may cause damage to the transformer in severe cases; increase line loss, increase power loss, reduce power supply efficiency, overheat the cable, and easily cause short circuit, fire and other hidden dangers; Affect the efficiency and normal operation of other electrical equipment, generate vibration and noise, and shorten the life of equipment

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