Technical Proposal: CT Reliability Enhancement Solution Based on Hybrid Gas Insulation
Application Scenario: Extreme cold regions (-40°C environment), environmentally stringent projects (e.g., Nordic wind power grid connection stations)
Core Goal: Enhance long-term reliability of Current Transformers (CTs) within Gas-Insulated Switchgear (GIS) while meeting low-carbon environmental requirements.
I. Insulation Medium Optimization: SF₆/N₂ Hybrid Gas Technology
- Parameter - Solution Design
- Gas Ratio: SF₆ (80%) + N₂ (20%) mixture
- Insulation Strength: At 20°C & 0.5MPa, insulation strength >85% of pure SF₆
- Environmental Performance: GWP (Global Warming Potential) reduced by 70%, significantly lowering greenhouse gas impact
- Low-Temperature Suitability: Hybrid gas liquefaction point ≤ -60°C, ensuring no liquefaction risk at -40°C in extreme cold environments
II. Anti-Partial Discharge Shielding Design
- Structural Innovation:
- Epoxy Resin Casting:
- CT coils manufactured using vacuum casting process, epoxy resin filling rate >99.9%, eliminating internal voids.
- Equipotential Metal Shielding Mesh:
- Zinc-plated copper mesh added to the outer layer of the casting body, maintained at equipotential to the CT primary conductor.
- Eliminates surface electric field distortion and suppresses partial discharge.
- Performance Validation:
- PD (Partial Discharge) level <5 pC (per IEC 60270 standard)
- Passed -40°C thermal cycling test, with no risk of insulation cracking.
III. Dynamic Temperature Rise Control System
- Intelligent Control Architecture:
Sensor Layer → Control Layer → Execution Layer
PT100 Temp Sensors → GIS Monitoring System → Fan Speed Control Module - Function Implementation:
- Real-time Monitoring: Built-in PT100 probes (±1°C accuracy) locate CT hotspot temperatures.
- Active Cooling: Automatically activates GIS fan arrays when temperature rise exceeds threshold (e.g., ΔT >40K).
- Energy Efficiency Optimization: Fan power dynamically adjusted based on demand, reducing wasted energy.
IV. Key Technical Advantage Comparison
|
Indicator |
Traditional SF₆ CT |
This Solution: Hybrid Gas CT |
|
Insulation Lifetime |
25~30 years |
>40 years |
|
GWP Value |
100% (SF₆=23,900) |
Reduced by 70% |
|
Low-Temp Reliability |
Prone to liquefaction at -30°C |
Stable operation at -40°C |
|
Partial Discharge Control |
10~20 pC |
<5 pC |
V. Scenario Adaptability Validation
- Extreme Cold Wind Power Scenario (Nordic):
- Passed -40°C /72h cold start test; CT ratio error ≤ ±0.2%.
- Optimized Pressure-Temperature curve for hybrid gas prevents excessive pressure drop at low temperatures.
- Environmental Compliance:
- Complies with EU F-gas Regulation (No.517/2014) restrictions on SF₆ usage.
- Life cycle carbon footprint reduced by 52% (per ISO 14067 standard).
