Dans des installations industrielles modernes, les secteurs manufacturiers particulièrement énergivores tels que la production de silicium monocristallin, le maintien d’une qualité d’énergie élevée est essentiel à la fiabilité opérationnelle, efficacité énergétique, and equipment longevity. As production automation and power electronics become increasingly prevalent, harmonic pollution has emerged as one of the most challenging power quality issues.
Chez CoEpower, we recently completed a successful harmonic mitigation project for a leading monocrystalline silicon manufacturer located in Ningxia, Chine. By deploying our CoEpo-APF-1200/0.4 Filtre d'alimentation actif, we significantly reduced harmonic distortion, restored stable operation of the compensation system, and improved overall electrical performance.
This article presents the project background, challenges, conception de solutions, commissioning results, and lessons learned from the field.
Contexte du projet
The customer operates a large-scale monocrystalline silicon manufacturing facility. The production process relies heavily on monocrystalline furnaces, which are nonlinear loads that generate substantial harmonic currents.
During routine power quality inspections, the customer discovered severe harmonic distortion throughout the low-voltage distribution network. The existing passive compensation system frequently malfunctioned and was unable to provide effective reactive power compensation due to harmonic resonance issues.
According to on-site measurements, the primary affected equipment was a:
- 3150 transformateur kVA
- 10 kV / 0.4 kV distribution system
- Multiple monocrystalline silicon furnaces
The customer required an immediate and reliable solution capable of:
- Reducing harmonic distortion
- Protecting electrical equipment
- Restoring capacitor bank operation
- Améliorer le facteur de puissance
- Ensuring compliance with power quality standards
Why Harmonics Are a Serious Problem in Silicon Manufacturing
Monocrystalline silicon production facilities utilize a large number of:
- Drives de fréquence variable (VFDS)
- Redresseurs
- Power electronic converters
- High-power heating equipment
Ces appareils tirent des courants non sinusoïdaux du réseau, creating harmonics that can lead to:
Surchauffe du transformateur
Excessive harmonic currents increase copper and iron losses, reducing transformer life expectancy.
Capacitor Failures
Capacitor banks may resonate with system inductance, causing overheating and frequent tripping.
Equipment Malfunctions
Sensitive control systems can experience false triggering, communication failures, and unexpected shutdowns.
Increased Energy Losses
Higher harmonic content results in additional system losses and reduced energy efficiency.
Poor Power Factor
Harmonics distort current waveforms, negatively affecting apparent power and increasing utility penalties.
For this Ningxia project, harmonic levels had already reached a point where the existing compensation system could no longer operate reliably.
CoEpower Solution Design
After conducting a comprehensive site survey and power quality analysis, our engineering team recommended the installation of a high-capacity active harmonic filtering system.
Équipement installé
| Parameter | Specification |
| Product Model | CoEpo-APF-1200/0.4 |
| Capacité de rémunération totale | 1200UN |
| Installation Quantity | 1 Cabinet |
| Transformer Capacity | 3150 kva |
| Tension du système | 400V |
| Emplacement d'installation | Behind Compensation Cabinet |
The APF cabinet dimensions were:
1200mm × 1000mm × 2200mm
The solution was designed to dynamically detect and compensate harmonic currents in real time, ensuring continuous power quality improvement under varying load conditions.
How Active Power Filters Work
Unlike traditional passive filters that target specific harmonic frequencies, Active Power Filters continuously monitor the electrical system and inject equal but opposite harmonic currents.
This process effectively cancels unwanted harmonics before they propagate through the network.
Key advantages include:
- Compensation harmonique en temps réel
- Dynamic load adaptation
- No resonance risk
- Simultaneous reactive power compensation
- Reduced maintenance requirements
- Fiabilité améliorée du système
For facilities with rapidly changing production loads, APFs are often the preferred solution compared to passive filtering technologies.
Installation and Commissioning
The commissioning process was carried out under normal production conditions to ensure accurate performance evaluation.
Test Equipment
The measurements were conducted using a:
FLUKE 435-II Power Quality Analyzer
Key specifications included:
- IEC 61000-4-30 Class A compliance
- Précision de tension: 0.1%
- Précision actuelle: 0.5%
- Comprehensive harmonic analysis capability
The testing location was the incoming distribution cabinet, allowing us to evaluate overall system performance before and after APF activation.
Harmonic Mitigation Results
The commissioning data demonstrated substantial improvements in both current and voltage quality.
Current THD Reduction
Avant indemnisation
Current Total Harmonic Distortion (THD):
28.9%
Après indemnisation
Current Total Harmonic Distortion (THD):
5.2%
This represents an approximate:
82% reduction in current harmonic distortion.
Voltage Quality Improvement
Before APF Operation
Voltage THD:
6.3%
After APF Operation
Voltage THD:
5.2%
Although voltage distortion was less severe than current distortion, the APF still produced a measurable improvement in voltage waveform quality.
Harmonic Order Analysis
The most dominant harmonics observed on-site were the:
- 5ème harmonique
- 7ème harmonique
- 11ème harmonique
The APF effectively suppressed these components.
| Harmonic Order | Avant l'APF | Après l'APF | Reduction |
| 5ème | 398.3 UN | 19.6 UN | 95% |
| 7ème | 169 UN | 12.5 UN | 92.6% |
| 11ème | 123.9 UN | 10.5 UN | 91.5% |
The reduction of these dominant harmonics significantly improved overall system stability and reduced electrical stress on transformers and capacitor banks.
Waveform Improvement
One of the most visible indicators of APF effectiveness was the transformation of system waveforms.
Avant indemnisation:
- Distorsion sévère de la forme d'onde
- Significant harmonic content
- Increased electrical stress
After compensation:
- Waveforms became nearly sinusoidal
- Lower distortion levels
- Improved power transmission efficiency
This improvement directly contributes to longer equipment lifespan and reduced maintenance costs.
Power Factor Optimization
In addition to harmonic mitigation, the APF system was configured to provide reactive power compensation.
After enabling compensation mode:
Power Factor Achieved
FP = 1.0
Achieving unity power factor provides several benefits:
- Pénalités réduites pour les services publics
- Improved transformer utilization
- Lower system losses
- Increased electrical efficiency
- Better voltage regulation
For industrial users with high monthly energy consumption, even small improvements in power factor can generate substantial cost savings over time.
Avantages sociaux
Following commissioning, the customer experienced several immediate advantages:
Improved Production Reliability
Reduced harmonic interference minimized risks of unexpected equipment shutdowns.
Enhanced Equipment Protection
Lower harmonic currents reduced thermal stress on transformers, câbles, et d'appareillage de commutation.
Stable Capacitor Operation
The existing compensation system could now operate without resonance-related failures.
Coûts de maintenance réduits
Cleaner power quality translates into longer equipment life and fewer repairs.
Future Expansion Readiness
The APF provides dynamic compensation capable of adapting to future production growth.
Conclusion
This project demonstrates how advanced Active Power Filter technology can effectively solve severe harmonic problems in high-energy industrial applications such as monocrystalline silicon manufacturing.
By installing the CoEpower CoEpo-APF-1200/0.4 Active Power Filter, the Ningxia facility achieved:
✔ Current THD reduced from 28.9% à 5.2%
✔ Voltage THD reduced from 6.3% à 5.2%
✔ 5th harmonic reduced by 95%
✔ Power factor improved to 1.0
✔ Near-sinusoidal current and voltage waveforms
✔ Reliable operation of the compensation system
As industries continue adopting more power electronic equipment, harmonic mitigation will become increasingly important for maintaining power quality and operational efficiency. CoEpower remains committed to delivering innovative APF solutions that help industrial customers achieve safer, cleaner, and more reliable electrical systems.
À propos de CoEpower
CoEpower specializes in power quality solutions including:
- Active Power Filters (APF)
- Générateurs de variables statiques (SVG)
- Filtres harmoniques hybrides
- Systèmes de correction du facteur de puissance
- Energy Efficiency Solutions
Si votre installation subit une distorsion harmonique, pannes de condensateur, transformer overheating, or poor power factor, contact CoEpower’s engineering team to discuss a customized power quality improvement solution.
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