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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.
Customer
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.
Solution
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:
Effectiveness
The effectiveness
of active power filter was significant, as shown in the data below:
|
Integrated |
THDi |
THDu |
Current (A) |
Power Factor (PF) |
|
Before |
28.9% |
6.5% |
941 |
0.83 |
|
After |
3.4% |
2.3% |
685 |
0.98 |
Conclusion
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
NO.25,JINHE RD,HUAIYUAN ECONOMIC DEVELOPMENT ZONE ,BENGBU,ANHUI
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