How To Deal With Harmonics In Power System?

Thereare many ways to suppress harmonic. In this paper, GDZX briefly introduces several methods to modify harmonic source itself.

I Try to select rectifier with high power factor

It is more traditional to reduce the harmonic by using the multiple rectifier. The rectifier constructed by this method is not enough to be called high power factor rectifier. The high power factor rectifier is a kind of combination device which can transform the rectifier itself to avoid harmonics as much as possible, and its current and voltage are in phase. This kind of rectifier can be called unit power factor converter (UPFC). This method can only be paid attention to in the process of equipment design, so as to get the effect of harmonic suppression in practice.

IIIncrease the number of phases rectified at the secondary side of the rectifier transformer

For equipment with rectifying elements, increasing the number of phases or pulsations of rectifying as much as possible can eliminate the low order characteristic harmonics better. This measure can reduce the harmonic content produced by harmonic source, which is generally considered in engineering design. By increasing the number of phases or pulsations, the low order harmonics can be effectively suppressed. However, although this method can be realized in theory, the cost in practical application is too high and the effect of eliminating harmonics is not good in technology. Therefore, this method is mostly used in large capacity rectifier load.

III The rectifier transformer adopts Y/ or /y wiring

This method can suppress the multiple high-order harmonics of 3. Taking the rectifier transformer as an example, when the high-order harmonic current is inversely connected from the thyristor to the secondary winding of the transformer, the multiple high-order harmonic current of 3 can not be connected, so it is naturally suppressed and does not exist. The advantage of this kind of harmonic suppression is that it can eliminate the integral times harmonic of 3. It is the basic method to suppress the high-order harmonic, which is mostly used for the load of large capacity rectifier device.

IV Multiplicity of rectifying circuit

The multiplicity of rectifying circuit means that multiple square waves are superposed to eliminate the harmonics with lower frequency, so as to obtain the step wave close to the sine wave. The more multiplicity, the closer the waveform is to sine wave, but the more complex the circuit is, so this method is generally only used in large capacity occasions. In addition, this method can not only reduce the harmonic of AC input current, but also reduce the harmonic amplitude of DC output voltage and improve the ripple frequency. If the above method is used with PWM technology, it will produce a good harmonic suppression effect. This method is used in bridge rectifying circuit to reduce the harmonic of input current.

The problem ofpower qualityhas been paid more and more attention in the development of modern technology. The new power quality testing instruments improve the monitoring, management and analysis of power quality, and establish a reliable power quality monitoring network. As a manufacturer of high-voltage test equipment,GDZXhas a professional technical team and large-scale productivity. It pays attention to industry related information, understands timely new trends, keeps pace with the times and develops innovation.