active power filter
Steel/non-ferrous metals industry
Jun 16, 2018

ZDDQ solutions for stable, efficient production in the metalworking industry.

The provision of an environmentally friendly water supply is one of the greatest challenges of the 21st century. In order to achieve the greatest degree of energy efficiency possible, power generation plants (e.g. solar power plants) are increasingly being integrated into modern treatment facilities, including frequency converters, in order to operate the electrical pumps with the power generated. However, these pumps can cause disruptive electric harmonics that make the use of active filters a necessity. Furthermore, many countries have complex regulations in place to ensure that power generation plants are properly connected to the power grid, and these regulations pose additional challenges.
With innovative products, ZDDQ offers its customers a wide range of possible solutions to address the challenges described above.


0.4kv Capacitor banks

6kv~35kv Capacitor banks

0.4Kv Static var generator

6~35kv statcom

Active Harmonic Filter

Are you sure that your production facilities are sufficiently protected against disruptions? We are happy to carry out a comprehensive grid analysis with you in order to proactively identify any possible problems. Naturally, should you have any questions, feel free to contact us at any time.

Our typical Project

Industry background
Dynamic reactive power, low power factors, and high harmonic content are common power quality problems in the metallurgical industry. Major contamination sources of power quality include the arc furnace, induction melting furnace, rolling mill, and electroplating, which contains rectification loads. The operation of an arc furnace is complex. During smelting and refining periods, harmonic current is irregular. When harmonics occur, dynamic reactive current and 3-phase imbalance are produced. The 3-phase arc furnace is commonly used in steel smelting and the single-phase arc furnace is often used in copper and copper alloy smelting.

During the smelting period, the power factor of arc furnace is below 0.7, and even drops to 0.1 after a short circuit. During the refining period, the power factor is only 0.8. Voltage fluctuates as reactive power is dynamic, and this can have a great impact on the grid and influence the normal operation of other loads.

Shandong Aluminium Factory Group (SAF), the largest AL product manufacturer in SD province.

Power quality problem description
SAF uses non-linear dynamic loads, such as arc furnaces and electroplating, extensively during copper smelting, and major problems include:

1.      The dynamic harmonic and reactive currents that cause grid voltage to fluctuate.

2.      Frequent failure of capacitor banks and reactive penalties from the power distributor due to low PF.

3.      Voltage distortion that exceeds national standards due to harmonic current.

4.      High maintenance costs due to high equipment failure rates.

Dynamic reactive and harmonic current management are implemented on the arc furnace connected to the 400V side. APF (single unit capacity 800A) was implemented as shown below:


The effectiveness of active power filter was significant, as shown in the data below:




Current (A)

Power Factor (PF)











APF has been running steadily at SAF for over three years. PF is steady at over 0.98; current THD was reduced from 28.9% to 3.4%; and current, voltage, and PF are now better than the national standard and power distributor requirements. The failure rate of both the arc furnace and electroplating equipment were significantly reduced. By decreasing the apparent current, thermal losses of the circuit were reduced. Meter monitoring shows energy saved to a specific degree. No resonance of the capacitor banks is reported for secure grid stability.

Site pictures

APF application in steel factory

Send a Message
welcome to zddq
If you are interested in our products and want to know more details,please leave a message here,we will reply you as soon as we can.