Optimal Operation of Railway. Power Supply Systems. Lars Abrahamsson, Nordic Seminar on Railway Technology, Bergen 141014 ...
Optimal Operation of Railway Power Supply Systems Lars Abrahamsson, Nordic Seminar on Railway Technology, Bergen 141014
Outline •
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•
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Introduction • General railway power systems background • Different ways of feeding – Some non-electricians here – Some Finns here Converter feeding in Sweden • Railway map • Voltage Source Converters, VSC (M2C) • Rotary (Q48/Q49) Optimal commitment of Rotary Converters • Main Idea • Results Questions & Discussion
General railway power systems background •
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Energy Efficiency of Electrified Railways • Most energy-efficient land-based means of transportation • Electrical motors > combustion engines • Power plants > diesel generators Improvements • New infrastructure – More of the same – Innovative design • More efficient use of existing infrastructure
Different ways of feeding (1/2) 50/60 Hz
50/60 Hz
DC or 15-25 Hz
50/60 Hz 1900-
1950-
Different ways of feeding (2/2) 50/60 Hz
50/60 Hz
16.7-25 Hz 50/60 Hz (exceptional)
DC 1970-
(GTO) (Gate turn-off)
1980-
Different ways of feeding (2/2) 50/60 Hz
50/60 Hz
6-pulse & 12 pulse rectifiers existed for longer time
16.7-25 Hz 50/60 Hz (exceptional)
DC 1970-
(GTO)
1980-
Swedish Power Supply System Map
VSC (Modular Multilevel Converters, M2C) • • •
Four quadrant controllability (active and reactive independent) Real-time active operation control Modules/blocks (M2C) • Optimized workload distribution (cf. Q48/Q49) • Block sizes from 12 to 120 MVA • Of total 600 MVA • Redundancy (modules can fail)
Rotary Converters (Q48/Q49) (1/2) •
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Controllability • Active and reactive power related • Power output follows voltage level/angle • Load-sharing – Unit commitment in station (experience) – Terminal voltage (avoid overloading) Benefits • Proven and reliable • Mechanical inertia (not software)
Rotary Converters (Q48/Q49) (2/2) •
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Facts • Synchronous or asynchronous to utility grid • Some models have adjustable stators • Will be around for some decades Idea • Existing equipment as efficient as possible • Focus on commitment (activation) this study • Minimize – No-load losses – Conversion losses – Transmission losses
Optimal commitment of Rotary Converters • Main idea: • Minimize system losses • With respect to converter commitment • Assuming load sizes & load positions known • 5 converter stations, equidistant • 2 trains
Optimal commitment of Rotary Converters (1/2) Station
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2
3
4
5
Committed (4)
1
1
0
0
1
Active Power
6.93 MW
7.52 MW
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3.63 MW
Reactive Power
0.88 MVAr
0.99 MVAr
-
-
0.21 MVAr
Train 1
12 MW
25 km
14.2 kV
Distance
Between
Train 2
4 MW
175 km
15.4 kV
Converters
50 km
Optimal commitment of Rotary Converters (2/2) Station
1
2
3
4
5
Committed (4)
2
2
0
0
1
Active Power
13.82 MW
13.125 MW
-
-
- 3.08 MW
Reactive Power
3.83 MVAr
3.89 MVAr
-
-
0.15 MVAr
Train 1
20 MW
25 km
11.5 kV
Distance
Between
Train 2
- 4 MW
175 km
17.4 kV
Converters
50 km
Future Work • Numerically more stable models • I admit present model unreliable • Severe voltage drops/long lines • Flat optimums • Voltage droop control (railway: compounding)
