A full spectrum active power filter with simple structure

Abstract

The key technique of active filter is to separate pure harmonics. A simple full spectrum active power filter (APF) is presented, which adopts LL series harmonic separation method to obtain pure harmonics. It uses harmonic energy to eliminate harmonic itself, belonging to the field of harmonic control. The non-sinusoidal voltage applied to the two LL series circuits composed of the primary and primary, secondary and secondary harmonic transformers will produce the fundamental currents I1, I2 in the same direction and the harmonic currents IX, IX' in the opposite direction in the two series branches due to the similarities and differences in the direction of the same name terminal of each transformer coil. The LL series circuit consists of two LL series circuits composed of the primary and secondary harmonic transformers. The fundamental magnetic flux generated by I 1 and I 2 in harmonic transformer cancel each other, and the coil of I 1 and I 2 is zero inductance to the fundamental wave, so the fundamental voltage falls on the fundamental transformer. The harmonic flux generated by IX, IX' in the fundamental transformer cancels each other, and the coil presents zero inductance to harmonic, so the harmonic voltage falls on the harmonic transformer, thus realizing the complete separation of harmonic and fundamental wave.

Description

1. Technical field [0001] The invention relates to a novel device capable of filtering out all harmonics of the full frequency spectrum of a power system. The device adopts a simple and effective harmonic separation technology——LL series harmonic separation method. This is an active filter device that eliminates the harmonic itself by completely utilizing the energy of the harmonic itself without inverter, and belongs to the technical field of harmonic control and energy saving. 2. Background technology [0002] The harmonics in the power system come from electrical equipment. The main contradiction that affects the quality of the grid voltage waveform is the nonlinear electrical equipment, that is to say, the nonlinear electrical equipment is the main source of harmonics. When the power system supplies power to nonlinear equipment, these While absorbing the fundamental wave energy, the equipment converts part of the fundamental wave energy into harmonic energy, and sends a ...

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Problems solved by technology

[0005] 3. For various electric welding machines, the ignition and violent changes of the arc form a highly non-linearity, which causes the current to fluctuate irregularly

[0014] (1) Harmonics cause additional power loss, heat generation, mechanical vibration and noise to rotating electrical machines;

[0015] (2) Harmonics cause additional loss to the power supply line;

Due to the many harmonic frequencies, there may be resonance, which will amplify the harmonic current and cause capacitors and other equipment to be burned

[0017] (4) Harmonics will cause relay protection and automatic devices to malfunction, and cause large errors in meters and electric energy measurement

[0032] It can be seen from the above that the active power filter overcomes the shortcomings of the passive filter and has good regulation performance. Not high, the cost is high, the components are easy to burn out, and the reliability is not high, so it is impossible to popularize and apply it in large quantities at this stage

[0033] my country's active filter technology is still in the research and test stage, and only a few prototypes are put into operation in industrial applications, which is not suitable for the increasingly serious harmonic pollution in my country

With the in-depth development of my country's power quality control work, the use of active filtering for harmonic control will have huge market application potential, but the high cost and low reliability of existing active filtering technology have become the bottleneck of its development

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