1 Introduction
2 Composition of three-phase traction power supply system
2.1 System structure
2.2 System voltage levels
3 Analysis on electrical characteristics of three-phase traction power supply system
3.1 System equivalent model and short-section current distribution
3.2 Voltage drops and loss for a single vehicle
3.3 Voltage drops and loss for multiple vehicles
4 Modeling three-phase traction power supply system
4.1 Chain network model of traction network
4.2 Parameter calculation of CTN
4.2.1 Calculation of cable impedance matrix
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Self-impedance of “core–earth” loop:
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Self-impedance of “sheath–earth” loop:
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Mutual impedance between any two loops:
4.2.2 Calculation of cable admittance matrix
4.3 Parameter calculation of TTN
5 Simulation analysis of three-phase traction power supply system
5.1 System simulation model
Parameter | Traction cable | Contact strip |
---|---|---|
Wire material | Copper | Copper |
Voltage level (kV) | 35 | 3 |
Sectional area (mm2) | 630 | 1000 (Equivalence) |
Ampacity (A) | 1160 | > 3500 |
Spacing (mm) | 140 | 200 |
\({Z}_{\mathrm{s}}\) (Ω/km) | 0.0776 + 0.7089i | 0.0678 + 0.6980i |
\({Z}_{\mathrm{m}}\) (Ω/km) | 0.0494 + 0.5529i | 0.0494 + 0.5305i |
\(C\) (10–7 F/km) | 2.50 | 7.33 |
5.2 Distribution law of traction current
5.2.1 Current distribution of short-section
Position (km) | \({I}_{\mathrm{L}}\) (A) | \({I}_{\mathrm{R}}\) (A) | ||
---|---|---|---|---|
Theoretical | Simulation | Theoretical | Simulation | |
0 | 734.2 | 730.5 | 0.0 | 3.7 |
1 | 680.1 | 680.6 | 75.6 | 75.1 |
2 | 623.3 | 624.3 | 155.8 | 154.8 |
3 | 559.2 | 560.7 | 239.6 | 238.1 |
4 | 487.0 | 489.2 | 324.7 | 322.5 |
5 | 408.1 | 411.0 | 408.1 | 405.2 |
6 | 324.9 | 328.6 | 487.3 | 483.6 |
7 | 239.7 | 244.2 | 559.2 | 554.7 |
8 | 156.0 | 161.4 | 623.9 | 618.5 |
9 | 75.7 | 82.0 | 681.3 | 675.1 |
10 | 0.0 | 7.2 | 731.7 | 724.5 |
5.2.2 Current distribution of two-stage power supply network
Position (km) | 12 | 28 | 35 | 43 |
---|---|---|---|---|
\(I\) (A) | 781.2 | 779.9 | 816.1 | 799.3 |
\({I}_{\mathrm{C}}\) (A) | 772.0 | 769.5 | 806.2 | 790.9 |
5.3 Voltage losses of traction network
5.4 Equivalent impedance of traction network and vehicle
5.5 Distribution of system voltage
5.5.1 Voltage distribution at no load
5.5.2 Voltage distribution at tight operation
5.6 Three-phase voltage unbalance factor
Sectional areas (mm2) | Voltage unbalance (%) |
---|---|
630 | 0.085 |
800 | 0.083 |
1000 | 0.081 |
5.7 Utilization rate of regenerative energy
Position | \({P}_{\mathrm{reg}}\) (MW) | \({P}_{\mathrm{L}}\)(MW) | \({P}_{\mathrm{MSS}}\) (MW) | Utilization (%) |
---|---|---|---|---|
– | – | 4.00 | 4.261 | – |
S1 | 2.00 | 4.00 | 2.304 | 97.85 |
S2 | 2.00 | 4.00 | 2.299 | 98.10 |
S3 | 2.00 | 4.00 | 2.298 | 98.15 |
S4 | 2.00 | 4.00 | 2.294 | 98.35 |
S5 | 2.00 | 4.00 | 2.264 | 99.85 |
5.8 Technical comparison of different power supply schemes
Index | TTPSS | AC 27.5 kV | DC 1.5 kV |
---|---|---|---|
Electrical phase separation | None | Existed | None |
Harm of stray current | Low | Low | High, and seriously threatening to underground facilities |
Utilization of regenerative energy | High and can be utilized directly | Low, mainly back to the grid | Difficult to utilize economically |
Negative sequence | None | Existed | None |
Insulation distance | Small | Large | Small |
Vehicle-mounted devices | AC-DC-AC converters + motors | Transformers + AC-DC-AC converters + motors | DC-AC converters + motors |
Power supply intermediary | Contact strip + rail | Rigid/flexible catenary | Rigid/flexible catenary or third rail |
Power supply capability | Superior | Superior | Relatively low |