Komprehensibong Solusyon sa Pagsasarili ng Performance para sa Transmission Transformers: Paghuhubog sa Cooling ug Pagbawas sa Magnetic Circuit Losses

1. Background and Challenges

Su kadaghanon nga paglambo sa mga load sa kuryente ug ang mas maong pangutana alang sa stable nga operasyon sa grid, ang mga transmission transformers naghaharap sa seryo nga mga hamubo bahin sa operational efficiency, kontrol sa temperature rise, ug long-term reliability. Ang labi ka taas nga temperatura sa operasyon nagpasabot og mas mabilis nga aging sa insulation materials, pagsayop sa lifespan sa equipment, ug pagtaas sa risk sa pagkapaso. Ang mataas nga magnetic circuit losses (primarily iron loss ug copper loss) nagbawas sa energy utilization efficiency, nagresulta og unnecessary nga operational costs. Aron matubag ang duha ka core issues nga kasagaran makita sa mga transmission transformers—excessive temperature rise ug significant magnetic circuit losses—gihimo kini nga comprehensive solution.

2. Solution Objectives

• Significantly Reduce Operating Temperatures: Kontrolhon ang top-oil temperature ug winding hotspot temperature sa safe operating margins.
• Effectively Reduce Magnetic Circuit Losses: Pokus sa pagbawas sa no-load losses (iron loss) ug load losses (copper loss), naaumento ang overall operational efficiency.
• Enhance Operational Reliability: Bawasan ang rate sa pagkapaso gikan sa overheating ug excessive losses, padayonon ang service life sa transformer.
• Optimize Total Life Cycle Cost: Padayonon ang economic efficiency sa transformer pinaagi sa energy savings ug pagbawas sa frequency sa maintenance.

3. Core Mitigation Measures

Gihimo kini nga solution usa ka integrated strategy sa "Source Control of Losses + Enhanced Heat Dissipation Capability + Precise Condition Management":

3.1 Cooling System Optimization and Upgrade, Improving Heat Dissipation Efficiency (Addressing Temperature Rise)

• Employ High-Efficiency Cooling Methods:
• Forced Air Cooling (OFAF/ODAF): Retrofit ang existing naturally air-cooled (ONAN) o air-forced cooled (ONAF) transformers, o iquip ang bag-ong units uban sa high-performance axial fans. Pilipon ang efficient, low-noise, ug weather-resistant fans combined with intelligent airflow control (e.g., automatic start/stop based on temperature or variable frequency drive adjustment) aron mahimulos ang air convection efficiency sa radiator surfaces ug mapabilis ang pagkuha sa heat.
• Forced Oil Water Cooling (OFWF): Prioritized para sa ultra-high-capacity transformers, units nga may high load factors, o ang mga nagsilbi sa high ambient temperatures. Iquip uban sa high-efficiency oil pumps ug plate heat exchangers aron gamiton ang water's high specific heat capacity para sa efficient heat exchange. Kinahanglan og supporting water treatment systems (to prevent scaling and corrosion) ug reliability assurance mechanisms (e.g., dual water circuits, standby pumps).
• Heat Pipe Assisted Cooling: Install heat pipe modules sa critical points sa radiators aron mahimulos ug mapabilis ang local hot spot heat pinaagi sa phase-change principle.
• Optimize Radiator Structure and Layout:
• Paggamit sa radiators nga may increased surface area (e.g., finned, panel radiators) ug optimized flow path designs.
• Ensure smooth flow paths for cooling media (air or water), eliminate local flow restrictions, ug improve heat dissipation uniformity.
• (For air cooling) Optimize fan positioning ug duct design aron masiguro ang uniform airflow coverage over radiator surfaces, minimizing dead zones.
• Intelligent Cooling Control:
• Automatically adjust cooling system output (fan speed/number, oil pump flow rate) based on real-time monitoring of oil temperature, winding temperature, ug ambient temperature. Achieves on-demand cooling, guaranteeing heat dissipation effectiveness while minimizing auxiliary equipment energy consumption.

3.2 Core Material and Structural Optimization, Reducing Iron Loss (Core Magnetic Loss Control)

• Select High-Performance Core Materials:
• Prioritize high-permeability, low-unit-loss cold-rolled silicon steel sheets (e.g., HiB steel) o more advanced amorphous alloy materials (offering significant advantages for no-load loss reduction).
• Strictly control silicon steel sheet thickness, flatness, ug insulation coating quality to minimize hysteresis losses ug eddy current losses.
• Optimize Core Design and Manufacturing Processes:
• Implement step-lap stacking techniques to minimize magnetic reluctance at joints, reducing additional iron losses.
• Precisely control core stacking factor ug clamping force to ensure uniform magnetic path distribution ug avoid local over-saturation.
• (Applying Advanced Technologies) Explore techniques like laser scribing (Laser Scribbling) to further optimize material magnetic domain structure.
• Optimize core grounding methods ug shielding to reduce stray losses in structural components.

3.3 Winding Design Optimization and Process Improvement, Reducing Copper Loss (Key Magnetic Loss Control)

• Optimize Winding Structure and Electromagnetic Design:
• Precisely calculate ampere-turn distribution, optimize conductor cross-section shape (e.g., using continuously transposed cables - CTC or self-bonding transposed cables - TTC) to minimize circulating current ug eddy current losses.
• Reasonably select conductor material (high-conductivity oxygen-free copper) ug current density, effectively reducing DC resistance losses while meeting temperature rise constraints.
• Optimize winding height, diameter, ug radial dimensions to control leakage flux ug reduce stray losses.
• Advanced Manufacturing Processes:
• Ensure uniform winding compactness using constant-tension winding equipment.
• Employ advanced Vacuum Pressure Impregnation (VPI) or resin casting processes to ensure thorough filling of gaps with insulating materials, improving thermal conductivity ug mechanical strength, thereby aiding heat dissipation ug reducing partial discharges.

3.4 Magnetic Circuit Condition Monitoring and Proactive Maintenance (Closed-loop Management, Ensuring Long-term Performance)

• Implement Precise Magnetic Circuit Condition Monitoring:
• Comprehensively assess magnetic circuit health by integrating online monitoring (e.g., Dissolved Gas Analysis - DGA, high-frequency partial discharge monitoring, vibration/acoustic noise monitoring, infrared thermography) ug offline testing (periodic winding deformation testing, no-load & load loss testing, core ground current testing).
• Focus Monitoring: Signs of core multi-point grounding faults, abnormal loss fluctuations, overheating of magnetic shields ug clamping structures.
• Establish a Preventive Maintenance Mechanism:
• Develop targeted magnetic circuit maintenance plans based on condition monitoring data ug operational history.
• Periodically inspect core and clamping structure grounding: Ensure reliable single-point grounding, promptly detect ug rectify multi-point grounding faults (which significantly increase iron losses ug cause overheating).
• Inspect magnetic shields, clamps, ug other structural components: Check for looseness, overheating, or discharge traces; promptly eliminate abnormalities.
• During core/lid lifting inspections, conduct focused checks ug maintenance on core lamination joints ug clamping condition.
• Perform in-depth diagnostic analysis on detected upward trends in abnormal losses to identify root causes ug implement corrective actions.

4. Expected Benefits

• Significant Reduction in Temperature Rise: Operating temperatures (especially hotspot temperatures) are expected to be effectively controlled, with reductions reaching projected targets (e.g., 15-25%), greatly alleviating thermal aging stress on insulation.
• Effective Reduction in Magnetic Circuit Losses:
• Iron loss (No-Load Loss): Expected reduction of 20-40% through new materials ug processes (especially significant when using amorphous alloys).
• Copper loss (Load Loss): Expected reduction of 10-25% through optimized winding design.
• Overall efficiency improvement of 1-3 percentage points, delivering considerable economic benefits ug carbon emission reduction.
• Substantial Improvement in Reliability: Failure risks caused by overheating ug magnetic circuit abnormalities are significantly reduced, enhancing equipment availability ug extending service life.
• Optimized Total Life Cycle Cost: Despite potentially higher upfront investment (e.g., high-performance materials, advanced cooling systems), the benefits derived from long-term energy savings, reduced maintenance costs, ug extended lifespan are more substantial, achieving a favorable Return on Investment (ROI).

5. Applicable Scope

This solution applies to newly built and in-service oil-immersed transmission (power) transformers at 35kV voltage level and above. Specific measures can be customized ug implemented based on the transformer's capacity, voltage level, operating environment, criticality, ug current condition.