IEEE Electrification Magazine - September 2016 - 10

Three-Phase, 33-kV, 50-Hz
Utility Distribution
Three-Phase, Three-Level, Single-Phase, Three-Level,
NPC Bridge
NPC Bridge
Feeder
Station 1
iss1

iss2

Feeder
Station 2

Feeder
Station 3

iss3

u
v

dc-Link Capacitors
and Second
Harmonic
Harmon
m ic
i Filter

w
d1 =
17.5 km

d2 =
32.5 km

d=
50 km

Overhead
Ov
Line

Figure 7. The train load supplied by three feeder stations with droop

Figure 9. The detailed structure of a back-to-back converter with one

control with line impedances in evidence.

three-phase and one single-phase bridge. NPC: neutral point clamped.

distance (87.5 km), the third station is providing power.
Because the load is purely resistive, and the line is
mostly inductive, the reactive power of each station is
expected to be slightly different. Thus, only active
power can be shared. Initial simulations look promising,
and further investigation is required for a complete

10

I E E E E l e c t r i f i cati o n M agaz ine / SEPTEMBER 2016

Current (A)

Voltage (kV)

description of the droop-control performance of a single-phase electrified network. The main benefit of this
scheme is that no communication, or external synchronization, is required between different converters.
The majority of power converter topologies for static
converter substations are based on voltage-source inverters, converting the three-phase ac
voltage to a dc and then to a singlephase ac. Figure 9 shows that dc5
link voltages can be up to 3.25 kV
for two-level H-bridges using 6.5-kV
0
IGBTs and up to 6.5 kV for threelevel neutral-point clamped bridg-5
0
1
2
3
4
5
6
7
8
9
10
es. Because the catenary is 25-kV
(a)
rms, a single-phase output transformer is required for most con5
verter topologies.
To increase the power of the
0
converter and the power quality,
the three-phase side is connected
-5
0
1
2
3
4
5
6
7
8
9
10
through a three-winding d-d-y
(b)
transformer using two three-phase
bridges. On the single-phase side,
5
multiple H-bridges are connected
in parallel via a multiple-winding
0
transformer, as shown in Figure 10.
This transformer has the second-5
0
1
2
3
4
5
6
7
8
9
10
ary windings connected in series to
(c)
reach the required voltage of the
overhead line. To reduce the distor50
1,000
tion of the single-phase current,
the pulsewidth modulation carriers
0
0
of the single-phase converters are
-50
-1,000
normally interleaved.
5.9 5.92 5.94 5.96 5.98
6
6.02 6.04 6.06 6.08 6.1
The back-to-back converter
(d)
has
a limited fault tolerance. If
Active Power (MW)
one of the dc-link capacitors fails,
Reactive Power (MVAR)
the converter cannot be operated.
This also applies to a short circuit
Figure 8. The three substations with droop-control sourcing and sinking load power: (a) substation 1,
(b) substation 2, (c) substation 3, and (d) traction load.
fault in any of the transistors of



Table of Contents for the Digital Edition of IEEE Electrification Magazine - September 2016

IEEE Electrification Magazine - September 2016 - Cover1
IEEE Electrification Magazine - September 2016 - Cover2
IEEE Electrification Magazine - September 2016 - 1
IEEE Electrification Magazine - September 2016 - 2
IEEE Electrification Magazine - September 2016 - 3
IEEE Electrification Magazine - September 2016 - 4
IEEE Electrification Magazine - September 2016 - 5
IEEE Electrification Magazine - September 2016 - 6
IEEE Electrification Magazine - September 2016 - 7
IEEE Electrification Magazine - September 2016 - 8
IEEE Electrification Magazine - September 2016 - 9
IEEE Electrification Magazine - September 2016 - 10
IEEE Electrification Magazine - September 2016 - 11
IEEE Electrification Magazine - September 2016 - 12
IEEE Electrification Magazine - September 2016 - 13
IEEE Electrification Magazine - September 2016 - 14
IEEE Electrification Magazine - September 2016 - 15
IEEE Electrification Magazine - September 2016 - 16
IEEE Electrification Magazine - September 2016 - 17
IEEE Electrification Magazine - September 2016 - 18
IEEE Electrification Magazine - September 2016 - 19
IEEE Electrification Magazine - September 2016 - 20
IEEE Electrification Magazine - September 2016 - 21
IEEE Electrification Magazine - September 2016 - 22
IEEE Electrification Magazine - September 2016 - 23
IEEE Electrification Magazine - September 2016 - 24
IEEE Electrification Magazine - September 2016 - 25
IEEE Electrification Magazine - September 2016 - 26
IEEE Electrification Magazine - September 2016 - 27
IEEE Electrification Magazine - September 2016 - 28
IEEE Electrification Magazine - September 2016 - 29
IEEE Electrification Magazine - September 2016 - 30
IEEE Electrification Magazine - September 2016 - 31
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IEEE Electrification Magazine - September 2016 - 33
IEEE Electrification Magazine - September 2016 - 34
IEEE Electrification Magazine - September 2016 - 35
IEEE Electrification Magazine - September 2016 - 36
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IEEE Electrification Magazine - September 2016 - 49
IEEE Electrification Magazine - September 2016 - 50
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IEEE Electrification Magazine - September 2016 - 52
IEEE Electrification Magazine - September 2016 - Cover3
IEEE Electrification Magazine - September 2016 - Cover4
https://www.nxtbook.com/nxtbooks/pes/electrification_december2022
https://www.nxtbook.com/nxtbooks/pes/electrification_september2022
https://www.nxtbook.com/nxtbooks/pes/electrification_june2022
https://www.nxtbook.com/nxtbooks/pes/electrification_march2022
https://www.nxtbook.com/nxtbooks/pes/electrification_december2021
https://www.nxtbook.com/nxtbooks/pes/electrification_september2021
https://www.nxtbook.com/nxtbooks/pes/electrification_june2021
https://www.nxtbook.com/nxtbooks/pes/electrification_march2021
https://www.nxtbook.com/nxtbooks/pes/electrification_december2020
https://www.nxtbook.com/nxtbooks/pes/electrification_september2020
https://www.nxtbook.com/nxtbooks/pes/electrification_june2020
https://www.nxtbook.com/nxtbooks/pes/electrification_march2020
https://www.nxtbook.com/nxtbooks/pes/electrification_december2019
https://www.nxtbook.com/nxtbooks/pes/electrification_september2019
https://www.nxtbook.com/nxtbooks/pes/electrification_june2019
https://www.nxtbook.com/nxtbooks/pes/electrification_march2019
https://www.nxtbook.com/nxtbooks/pes/electrification_december2018
https://www.nxtbook.com/nxtbooks/pes/electrification_september2018
https://www.nxtbook.com/nxtbooks/pes/electrification_june2018
https://www.nxtbook.com/nxtbooks/pes/electrification_december2017
https://www.nxtbook.com/nxtbooks/pes/electrification_september2017
https://www.nxtbook.com/nxtbooks/pes/electrification_march2018
https://www.nxtbook.com/nxtbooks/pes/electrification_june2017
https://www.nxtbook.com/nxtbooks/pes/electrification_march2017
https://www.nxtbook.com/nxtbooks/pes/electrification_june2016
https://www.nxtbook.com/nxtbooks/pes/electrification_december2016
https://www.nxtbook.com/nxtbooks/pes/electrification_september2016
https://www.nxtbook.com/nxtbooks/pes/electrification_december2015
https://www.nxtbook.com/nxtbooks/pes/electrification_march2016
https://www.nxtbook.com/nxtbooks/pes/electrification_march2015
https://www.nxtbook.com/nxtbooks/pes/electrification_june2015
https://www.nxtbook.com/nxtbooks/pes/electrification_september2015
https://www.nxtbook.com/nxtbooks/pes/electrification_march2014
https://www.nxtbook.com/nxtbooks/pes/electrification_june2014
https://www.nxtbook.com/nxtbooks/pes/electrification_september2014
https://www.nxtbook.com/nxtbooks/pes/electrification_december2014
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