Comparison and Economic Analysis of Current Carrying Capacity Between Power Frequency Transmission and Low-Frequency Transmission
Time: 2025-03-17 15:36:47
Source: Henan Province Jianyun Cable Co., Ltd.
Introduction
In the field of offshore wind power transmission, the current carrying capacity and economic feasibility of low-frequency transmission (20 Hz) and power frequency transmission (50 Hz) have become critical topics. This study utilizes COMSOL software to establish an electromagnetic-thermal-fluid coupling simulation model to analyze the current carrying capacity and cost-effectiveness of both systems.
1. Key Findings from the Study
1.1 Reduced Losses with Low-Frequency Transmission
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When voltage level, cable section, and laying parameters remain unchanged, conductor losses, sheath losses, and armor losses decrease with lower load frequency.
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The reduction trend becomes more significant as the load current increases.
1.2 Cross-Section Reduction
Compared with power frequency transmission, low-frequency transmission allows the submarine cable conductor cross-section to be reduced by 1 to 3 levels, depending on transmission conditions.
1.3 Improved Economic Performance
For a 600 MW offshore wind farm, using 220 kV submarine cables, the economic advantage of low-frequency AC transmission becomes evident when the transmission distance reaches 32 km.
2. Technical Comparison: Power Frequency vs. Low-Frequency Transmission
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Parameter
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Power Frequency (50 Hz)
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Low-Frequency (20 Hz)
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Conductor Loss
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High
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Lower
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Sheath Loss
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High
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Significantly Lower
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Armor Loss
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High
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Reduced
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Cross-Section
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Large
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Reduced by 1-3 Levels
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Economic Advantage
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Not obvious
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Significant at 32 km+
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3. Current Carrying Capacity Analysis
3.1 Simulation Model
Using COMSOL's electromagnetic-thermal-fluid coupling model, the current carrying capacity of 220 kV submarine cables was analyzed under different frequencies.
3.2 Loss Distribution
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Loss Type
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Power Frequency (50 Hz)
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Low Frequency (20 Hz)
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Conductor Loss
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60.75 W/m
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53.33 W/m
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Sheath Loss
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9.75 W/m
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1.72 W/m
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Armor Loss
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10.39 W/m
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2.32 W/m
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Total Loss
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80.89 W/m
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57.37 W/m
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4. Economic Analysis of Transmission Cost
4.1 Total Cost Calculation Formula
Ptotal=Pinvestment+Ploss+PmaintenanceP_{total} = P_{investment} + P_{loss} + P_{maintenance}Ptotal=Pinvestment+Ploss+Pmaintenance
4.2 Cost Breakdown for 100 km Transmission Line
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Transmission Capacity
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Power Frequency Cost (¥ Million)
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Low-Frequency Cost (¥ Million)
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600 MW
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291.48
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252.88
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228 MW
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126.48
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125.27
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5. Conclusion
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Low-frequency transmission reduces total power loss, especially in sheath and armor layers.
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With the same transmission capacity, low-frequency transmission allows for smaller conductor cross-sections, reducing material costs.
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Economic benefits start appearing at 32 km transmission distance for 600 MW offshore wind farms.
6. Keywords
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Low-Frequency Transmission
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Current Carrying Capacity
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Offshore Wind Power
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Submarine Cable Loss Analysis
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Economic Feasibility of Power Transmission
7. References
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Wang Dongxu et al. (2024). Comparison and Economic Analysis of Current Carrying Capacity Between Power Frequency Transmission and Low-Frequency Transmission. Wire & Cable, No.6, 2024. DOI: 10.16105/j.dxdl.1672-6901.202406010
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GB/T 12706-2008 - Electric Cable Standard
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IEC 60287 - Current Capacity Calculation Standard
