Application background:

　　1). The load types of the above-mentioned industries are mainly power electronic rectifier power supplies and variable frequency speed control devices that will generate 5th, 7th, 9th, 11th, 13th and other harmonics. With twelve pulse and twenty-four pulse rectifiers The popularity of low-order harmonics gradually decreases, and the 23rd and 25th harmonic currents gradually increase;

　　2) The working mode of the equipment is dynamic impact operation. The single machine capacity of the equipment is large, the amplitude and frequency of active power and reactive power vary greatly, and it has a certain periodicity.

　　3), causing system voltage fluctuations and flicker, low power factor, unbalanced three-phase current, increased line loss, excessive harmonic content, etc.

　　Recommended plan:

　　Install digital reactive power generators (DVG) and active power filters (APF) on the low-voltage side bus (generally 0.4kV) to improve power factor, solve reactive power fluctuations and avoid over-compensation, and filter out high Subharmonics.

　　Design capacity of active filter = operating current * current distortion rate

　　Note: In order to make the compensation effect better, there is generally a margin. Therefore, the effective harmonic current under the maximum load rate is generally calculated by multiplying 1.2 as the final configuration capacity.

　　Customer benefits:

　　The power quality meets national standards, avoiding fines from power companies

　　The improvement of power quality makes the power supply system safe and reliable

　　Effectively control harmonics to avoid interference to sensitive equipment

　　Reduce equipment loss, reduce equipment maintenance costs, and extend service life