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How a Copper Manufacturing Plant Solved Severe Harmonic Issues with SVG + APF Technology
Real-world case study: Improving power quality, restoring capacitor operation, and eliminating production disruptions at Zhejiang Jinjia Special-Shaped Copper Co., Ltd.
The Challenge: High Harmonics, Failed Capacitors, and Unstable Production
Zhejiang Jinjia Special-Shaped Copper Co., Ltd., located in Changxing County, Huzhou, is a leading manufacturer of high-precision oxygen-free copper rods, busbars, and specialty copper products. The facility operates multiple production lines powered by induction furnaces, frequency converters, and other non-linear loads — all of which generate significant harmonic distortion.
During routine operations, the plant faced critical power quality issues on its #3 1600kVA transformer:
Initial measurements revealed:
| Parameter | Measured Value |
| Total Harmonic Voltage Distortion (THDv) | Up to 7.72% |
| Total Harmonic Current Distortion (THDi) | Up to 28.5% |
| Dominant Harmonics | 5th, 11th, 13th |
| Reactive Power Demand | 781 kvar |
Conclusion: The #3 transformer was suffering from severe harmonic pollution, causing resonance with existing capacitor banks and making power factor correction impossible.
Root Cause Analysis: Harmonic Resonance and System Instability
Further testing showed:
This confirmed that non-linear loads (especially VFDs and rectifiers) were injecting harmonics into the system. When traditional capacitor banks were switched on, they formed parallel resonance circuits with system inductance, amplifying harmonic currents — leading to failures.
The Solution: Hybrid SVG + APF Active Compensation System
To solve this, a hybrid active power quality solution was designed and deployed:
| Device | Device | Quantity | Function |
| Static Var Generator (SVG) | SVG-100kvar | 8 units | Provides dynamic reactive power compensation (total 800kvar) |
| Active Power Filter (APF) | APF-150A | 3 units | Filters 2nd–50th odd harmonics |
Alternative Option: Replace existing capacitors with 7% detuned reactors + capacitors to avoid resonance.
Results: Immediate Improvement in Power Quality
After installation and commissioning, measurements showed dramatic improvements:
| Parameter | Before | After | Improvement |
|---|---|---|---|
| Power Factor | 0.61 | >0.95 | +55% |
| THDv (Voltage) | 7.72% | <3% | -60% |
| THDi (Current) | 28.5% | <5% | -82% |
| Capacitor Operation | Failed | Stable & Functional | Restored |
| VFD Startup Reliability | Unreliable | 100% Success | Resolved |
Why This Matters for Industrial Manufacturers
This case highlights a common but often overlooked issue in modern factories:
"You can’t fix power factor with capacitors if harmonics are present."
Traditional capacitor banks can make harmonic problems worse, leading to:
The solution? Active compensation technology:
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