Utilizing Wayside Energy Storage Substations in … · Utilizing Wayside Energy Storage Substations...

8 –Technical Forums Energy, Environment & Transit

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Utilizing Wayside Energy Storage Substations in Rail

Transit Systems – Some Modelling and Simulation

Results

J.G.Yu, PhD SYSTRA Consulting,Inc

Philadelphia, PA

Martin P. Schroeder American Public Transportation

Association Washington, DC

David Teumim Teumim Technical, LLC

Allentown, PA

Keywords: DC Traction Power Systems, Energy Storage

Devices, Wayside Energy Storage Substations, Computer

Simulation; Energy Savings.

Abstract

The APTA / EPRI Energy Storage Research Consortium [1]

study team, funded by the Transportation Research Board

TCRP program, conducted a study of wayside energy storage

systems coupled with track propulsion networks of actual

system designs. Adding energy storage is aimed at reducing

energy consumption through improved capture of regenerative

braking energy, reduced energy costs through reduction of

peak power demand, improvement of power quality through

low-voltage support, and use of energy storage systems as

supplements to or replacements for conventional electrical

substations under specific conditions. Computer simulations

are performed to assess the benefit of wayside energy storage

systems starting with a look at voltage support.

Introduction

Energy storage devices (ESD) for transit may take different

forms, such as flywheels, batteries, electrochemical capacitors,

or hybrid devices (batteries combined with electrochemical

capacitors, and other variations). Such devices have seen rapid

development in recent years. Their applications have spread

from traditional roles as small scale Uninterruptible Power

Supplies (UPS) to utility scale storage devices.

In DC-traction power systems, wayside energy storage

substations (WESS) using ESD are emerging as a viable

supplement to traditional substations for traction power system

designers. A WESS can be located on its own anywhere along

the track, without the need of medium voltage power supply

sources from the utility. However, it is also recognized that a

WESS can be tied to an AC utility supply using DC/AC

inverters should there be interest in sharing the benefits of

storage between transit systems and utilities, both sharing

similar needs in power quality and peak power reduction. The

systems studied here however, only address a DC connected

WESS. The following discussion will focus on the potential

benefit of ESD-substations to correct voltage support problems

and improve capture ratio of available regenerative braking

energy. Results will also highlight how various general design

parameters affect the performance of energy storage systems.

1 A Typical WESS Design

The main components of a WESS installation and a traditional

rectifier substation are compared in the following figure.

Figure 1: Comparison of the main components between a

rectifier substation and a WESS

The core components of most wayside energy storage

substations consist of a storage medium and a power control

unit, as well as the necessary DC bus and switchgear for


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power distribution to the track, third rail or overhead contact

systems (OCS).

Control of WESS charging and discharging cycles is based on

voltage levels as shown in Figure 2.

Figure 2: Power control diagram for WESS

The main parameters that define a WESS design are:

Energy storage capacity (kWh)

Power rating (kW)

Power conversion efficiency

Maximum current (charging or discharging) (amps)

Control voltage (Vc) and various other voltage levels

for charging and discharging control (volts)

Computer models have been developed that include these

energy storage device parameters [2]

and the associated

constitutive power distribution models of the traction power

systems. Computer simulations predict full-system operating

behaviour, energy storage performance and establish the

degree of sensitivity to various system design parameters.

Additional general system parameters used in simulations

included variables defining electrical performance of circuit

breaker houses and substations, electrical resistances of third

rail and return rail, substation capacity, track alignment data,

vehicle braking and propulsion capabilities, and operational

data such as train headway scheduling, station dwell times,

off-peak operating changes, and various other parameters.

To further identify optimal locations of energy storage devices

within the alignment of candidate conventional propulsion

system designs, simulations without energy storage are

conducted first to establish potential weaknesses within the

system associated with problems of voltage sag or

regenerative braking energy capture. This type of analysis was

conducted for three families of rail systems including light

rail, heavy rail and commuter rail. From these families,

representative system designs were chosen and energy storage

systems sized based on simulation results, energy storage

characteristics, and analysis of data taken from actual

operating transit agencies.

Simulations were performed on three representative systems

organized. For each system, simulation results predicted

performance of the overall system as well as the energy

storage benefit.

Light Rail

System parameters

The main parameters of the light rail transit (LRT) system

being simulated are listed as follows:

7 Miles of track (double track system)

12 Stations

750V nominal voltage DC traction power system,

7 Traction power substations (TPSS); each equipped with

1.5MW rectifier unit

1 Circuit breaker house (CBH)

2 car trains in operation with regenerative braking

5 Minute headway in peak hours

15 Minute headway in off peak hours and weekends

The following figure shows the motoring and regenerative

braking control diagram for a typical LRT vehicle.

Figure 3: Power control diagram for the LRT vehicle

Train voltage support requirement

Train voltage is a critical performance parameter for the

traction power system. For this particular system, when a

train’s voltage falls below 575V (see Figure 3) corresponding

to a voltage sag condition, the train’s power demand cannot be

fully met by the traction power system, which will have an

adverse impact on the performance of the train. At or below

500V, the train’s traction power motor will be shut down in

order to avoid damage to the equipment.

Under normal conditions (when all substations are in service),

the simulated train voltages are all above 575V, which are

adequate for trains to achieve their on-time performance.

However, when the rectifier in positions A4 or A5 TPSS is out

of service, the minimum train voltage can fall to 504V and

559V respectively. These sags are shown in the following


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figures where it is noted that the data points represent

solutions at time steps in the simulation.

Simulated Train Voltages

(Case 64 - A4 Outage, 5-Minute Headway)

100

200

300

400

500

600

700

800

900

1,000

24.5 25.0 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0 31.5 32.0

Location (miles)

Tra

in V

olt

ag

e (

V)

Train Voltage

Substations

Stations

A1-T

PS

SS

T 0

1

A4-O

UT

ST

07

A6-T

PS

S

A5-T

PS

S

A7-T

PS

S

A2-T

PS

S

A3-T

PS

S

ST

02

ST

03

ST

04

ST

05

ST

06

ST

08

ST

09

ST

12

ST

10

ST

11

A4X

-CB

H

Figure 4: Train voltages under A4-TPSS outage condition


(Case 65 - A5 Outage, 5-Minute Headway)

100

200

300

400

500

600

700

800

900

1,000

24.5 25.0 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0 31.5 32.0

Location (miles)

Tra

in V

olt

ag

e (

V)

Train Voltage

Substations

Stations

A1

-TP

SS

ST

01

A4

-TP

SS

ST

07

A6

-TP

SS

A5

-Ou

t

A7

-TP

SS

A2

-TP

SS

A3

-TP

SS

ST

02

ST

03

ST

04

ST

05

ST

06

ST

08

ST

09

ST

12

ST

10

ST

11

A4

X-C

BH


In order to avoid the excessively low voltage conditions when

the rectifier in A4 or A5 TPSS is out of service or has failed,

either a full rectifier substation or a WESS at A4X-CBH

location can be considered as a reinforcement. Addition of

energy storage (WESS) will help support the voltage sag and

provide a potential energy saving benefit by improving capture

of regenerative braking. This simulation and analysis process,

by which we begin with a look at voltage support first and

energy saving second is carried throughout the various mode

analyses.

New WESS option

Returning to the example above, if an appropriately sized

WESS is installed in location A4X, the resulting train voltage

improvements can be shown in Figures 6-7, given that

rectifiers at positions A4 or A5 TPSS are removed.


(Case 74b - A4 Outage, 5-Minute Headway)

100

200

300

400

500

600

700

800

900

1,000

24.5 25.0 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0 31.5 32.0

Location (miles)

Tra

in V

olt

ag

e (

V)

Train Voltage

Substations

Stations

A1-T

PS

SS

T 0

1

A4-O

UT

ST

07

A6-T

PS

S

A5-T

PS

S

A7-T

PS

S

A2-T

PS

S

A3-T

PS

S

ST

02

ST

03

ST

04

ST

05

ST

06

ST

08

ST

09

ST

12

ST

10

ST

11

A4X

-ES

D



(Case 75b-ESD760V - A5 Outage, 5-Minute Headway)

100

200

300

400

500

600

700

800

900

1,000

24.5 25.0 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0 31.5 32.0

Location (miles)

Tra

in V

olt

ag

e (

V)

Train Voltage

Substations

Stations

A1-T

PS

SS

T 0

1

A4-T

PS

S

ST

07

A6-T

PS

S

A5-O

ut

A7-T

PS

S

A2-T

PS

S

A3-T

PS

S

ST

02

ST

03

ST

04

ST

05

ST

06

ST

08

ST

09

ST

12

ST

10

ST

11

A4X

-ES

D


The above figures indicate that the new WESS installation in

A4X location will be adequate for train voltage support with

either A4 or A5 TPSS rectifier removed. The minimum train

voltages for a system with energy storage are summarized in

Table 1.

Table 1Minimum Train Voltage and ESD Energy Summary

Case # Scenario A4X Type

Minimum

Train

Voltage (V)

Voltage

Improveme

nt (V)

ESD Energy

(kWh)

64 A4 outage CBH 504 n/a n/a

74b A4 outageESD

(Vc=760V)588 84 3.1

84 A4 outage TPSS 605 101 n/a

65 A5 outage CBH 559 n/a n/a

75b A5 outageESD

(Vc=760V)630 71 3.7

85 A5 outage TPSS 632 73 n/a

Note - ESD power rating at 1500 kW


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WESS parameters

With the installation of the WESS in location A4X, the

system’s receptivity (the ratio of utilized regenerative energy

over the total available regenerative energy) will also be

improved, resulting in a greater potential to recover

regenerative braking energy. As a result, the energy saving

ratio due to regenerative braking (the ratio of energy

consumption with regenerative braking over the energy

consumption without regenerative braking) can be improved.

When all substations are in service and we do not experience a

voltage sag problem, we can take a different look at the effect

of energy storage, principally to save energy. The control

voltages of the WESS may be adjusted to best optimize energy

saving rather than providing voltage support, thus maximizing

the capture of regenerative energy. So, when voltage support is

not needed, an adjustment in the voltage settings of the WESS

can be made for optimal energy saving. Table 2 compares

system-wide energy saving potential resulting from variations

in WESS control voltages. This table also demonstrates the

corresponding energy and power rating requirements for the

WESS. An electricity cost saving analysis utilizing this

strategy is undertaken in the next section.

Table 2 System-wide Energy Summary

Case # A4X TypeReceptivity

(%)

Energy

Savings (%)

ESD Energy

(kWh)

60 CBH 83.6 29.9 n/a

70aESD

(Vc=720V)84.1 30.1 0.20

70bESD

(Vc=760V)84.5 30.2 1.30

70cESD

(Vc=793V)88.0 31.5 2.30

80 TPSS 83.3 29.8 n/a

Note - All TPSS in normal operation

Electricity cost saving analysis

We have shown that a WESS can effectively mitigate

problems associated with low train voltages. To examine the

potential energy and cost saving benefits of energy storage, a

simple electricity cost analysis can be performed using the

options noted above. We start with a comparison of the 15-

minute power averages across all substations in the system

under normal operation with and without a WESS, as shown in

Table 3. The 15-minute averages are used because of the

correlation with utility peak power charging average time

periods, which are in most cases 15-minutes.

Table 3 15-Minute Average Power Values by Substation

With A4X-

TPSS

With A4X-

ESD

With A4X-

TPSS

With A4X-

ESD

A1 403 406 162 165

A2 449 458 178 185

A3 388 408 152 156

A4 382 410 153 159

A4X 208 0 81 0

A5 366 395 137 144

A6 412 425 153 162

A7 361 368 134 138

Sum 2,969 2,870 1,150 1,110

15-Minute Average Power (kW)

5-Minute Headway 15-Minute Headway

Substation

From the table it can be seen that the 15-minute average power

in each substation for 5-minute headways represents the peak

power demand, while 15-minute headways are less as

measured over the same 15 minute period. What this table

shows is the utility supplied power to each substation along

the alignment. Higher power requirements are shown near the

WESS because there is no supply at that point and

neighbouring substations would need to provide the additional

power to charge the WESS, although only marginally. Both

the 5-minute and 15-minute headway conditions are used to

compute the overall energy saving in a 24 hour period. More

specifically, the following 24-hour train operation schedules

are assumed:

5-minutes in peak hours (6-10Am and 4-8PM)

15-minutes in off-peak hours and weekends

No train service between 1AM and 4AM on any day

Using actual published electricity tariffs from a USA utility

company [3]

, the annual cost for each substation is calculated

based on individual traction substation billing arrangements

and the power demands noted in Table 3. These are listed in

Table 4.

Table 4 indicates that the WESS installation will have an

annual electricity cost benefit of $45,000 (based on the current

tariffs) compared against a full rectifier installation in the A4X

location. Additional cost benefits may be possible because a

WESS is typically less expensive than a full rectifier utility

substation.


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Table 4 Summary of Annual Electricity Cost Saving due to

WESS (all figures in US $)

SubstationWith A4X-

TPSS

With A4X-

WESS

Savings with

WESS

A1 $182,342 $184,763 -$2,422

A2 $202,057 $207,687 -$5,630

A3 $173,973 $181,808 -$7,835

A4 $172,945 $183,581 -$10,637

A4X $93,875 $0 $93,875

A5 $161,894 $172,907 -$11,012

A6 $181,397 $189,110 -$7,713

A7 $159,353 $162,810 -$3,456

Sum $1,327,835 $1,282,666 $45,169

Annual Electricity Cost Summary

Metro Rail

System parameters

A similar simulation analysis, again looking at the conditions

of low voltage and regenerative braking energy, is performed

for a heavy rail (subway) system using the simulation

parameters below.

5 Miles Metro System; 4 Stations

700V DC traction power system

4 Traction substations

2 Circuit breaker houses (CBH)

8 Car trains with regenerative braking

2 Minute in peak hours (AM & PM)

5 Minute headway in mid day hours

15 minute headway in off peak and weekend operations

To set up the model, Figures 8-9 show the motoring and

regenerative braking control diagram for a typical metro rail

vehicle and the conditions of low voltage. Simulations will

utilize these characteristics. For this case, sensitivity analyses

are performed to characterize the influence on system design

parameters on overall energy storage performance.

Simulation results indicate that there will be low voltage

occurrences at the east end of the track, as shown in Figure-9.

Figure 8: Power control diagram for the Metro rail vehicle


0

100

200

300

400

500

600

700

800

900

1,000

7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5

Location (miles)

Tra

in V

olt

ag

e (

V)

Train Voltage

Substations

Stations

Minimum Voltage

G0

2A

-

PS

SS

top

-

2

G0

4-

TP

SS

G0

5B

-

CB

H

G0

5A

-

TP

SS

G0

2B

-

CB

H

G0

3-

TP

SS

Sto

p-

3

Sto

p-

4

Sto

p-

5

Case 430-2 Min Headway; 750-840V Regen Taper; No ESD

Figure 9: Train voltages with CBH at G05B

The effect of ESD power rating

If an ESD is installed at position G05B at the east end of the

track, the low voltage conditions will be improved. A 3MW

installation is required to achieve 525V or better, as shown in

Figure 10.


0

100

200

300

400

500

600

700

800

900

1,000

7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5

Location (miles)

Tra

in V

olt

ag

e (

V)

Train Voltage

Substations

Stations

Minimum Voltage

G0

2A

-

PS

SS

top

-

2

G0

4-

TP

SS

G0

5B

-

3M

W

ES

D

G0

5A

-

TP

SS

G0

2B

-

CB

H

G0

3-

TP

SS

Sto

p-

3

Sto

p-

4

Sto

p-

5Case 431-2 Min Headway; 750-840V Regen Taper; 3MW ESD

Figure 10: Train voltages with 3MW ESD at G05B

A larger installation of 4MW will achieve an even better

result. Simulated load and energy cycles for the ESD are

shown in Figures 11-12.


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Simulated ESD Load Cycle

-4,000

-3,000

-2,000

-1,000

0

1,000

2,000

3,000

4,000

7:40 7:41 7:42 7:43 7:44 7:45

Time

Po

wer

(kW

)

3MW ESD

4MW ESD2 Minute Headway

Figure 11: Simulated ESD load cycles

Simulated ESD Energy Cycle

4

6

8

10

12

14

16

18

20

22

7:40 7:41 7:42 7:43 7:44 7:45

Time

En

erg

y (

kW

h)

3MW ESD

4MW ESD2 Minute Headway

Figure 12: Simulated ESD energy cycles

The effect of headway offset

For peak hour operation (2 minute headway), simulations were

carried out for different offsets between east and west bound

train’s dispatching timing (headway offsets). Such offsets

result in the trains meeting at different locations, which in turn

affect the train voltage and other conditions in the system.

Time-distance plots for three different headway offsets on

west bound trains are illustrated in the following figure.

Simulated Trains

7:40

7:41

7:42

7:43

7:44

7:45

7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5

Location (miles)

Tim

e (

hh

:mm

)

WB Offset by 0s

WB Offset by 15s

WB Offset by 30s

Substations

Stations

G0

2A

-

PS

SS

top

-

2

G0

4-

TP

SS

G0

5B

-

TB

D

G0

5A

-

TP

SS

G0

2B

-

CB

H

G0

3-

TP

SS

Sto

p-

3

Sto

p-

4

Sto

p-

5

Time-Distance Plots; 2 Minute Headway

Figure 13: Time-distance plot for peak hour trains under

different headway offsets for WB trains

Minimum train voltages and system receptivity (the ability to

accept regenerative power) under different installations at

different headway offsets are shown in the following figure.

Minimum Train Voltages by Different Installations

(2 Minute Headways; 840V Voltage Limit)

497

604

558

627

655644

593

547

634

617617

562

637

619

520

651

400

450

500

550

600

650

700

0 15 30 45

WB train headway offset (seconds)

Vo

ltag

e (

V)

CBH

3MW Sub

3MW ESD

4MW ESD

Figure 14: Minimum train voltages versus headway offsets

System Receptivity Under Different Installations

(840V Voltage Limit)

67.4

86.9

72.2

66.0

58.1

89.7

76.3

69.5

61.7

72.8

59.1

87.6

61.8

69.7

76.7

90.1

50

55

60

65

70

75

80

85

90

95

0 15 30 45

Headway offset for WB trains

Sy

ete

m R

ece

pti

vit

y (

%)

CBH

3MW Sub

3MW ESD

4MW ESD

Figure 15: System receptivity versus headway offsets

Many factors affect the system receptivity and energy saving

figures, such as track alignment, passenger station locations,

electrical parameters of the traction power system, vehicle

characteristics, train operational characters (acceleration and

braking rates, coasting, offsets in headway dispatches on the

two tracks, timing deviation from regular headways, etc.). The

figures contained in this paper represent nominal conditions.

Variations from these figures can be expected when system

conditions change, but such detailed comparative analyses are

beyond the scope of this investigation. However, the following

sections illustrate the general impact on system performance

given such variations.

The effect of voltage limit

Receptivity variations versus voltage limits are shown in the

following figure.


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System Receptivity Under Voltage Limits

(2 Minute Headway)

69.5

95.74

82.93

77.46

68.62

76.3

61.7

89.7

72.17

79.24

84.38

97.41

55

60

65

70

75

80

85

90

95

100

0 15 30 45

Headway offset for WB trains

Sy

ete

m R

ece

pti

vit

y (

%)

840V Voltage Limit

900V Voltage Limit

970V Voltage Limit

Figure 16: System receptivity versus voltage limits

The effect of headway

Receptivity variations versus headways are shown in the

following figure.

System Receptivity Under Different Installations

(840V Voltage Limit)

68.6

49.7

86.9

68.4

49.5

89.7

77.3

63.5

90.1

77.6

65.1

87.6

45

50

55

60

65

70

75

80

85

90

95

2 5 15

Headway (minutes)

Syete

m R

ece

pti

vit

y (

%)

CBH

3MW Sub

3MW ESD

4MW ESD

Figure 17: System receptivity versus headway

Energy cost savings

The estimated annual cost for the track section and cost

savings [3]

under different options are shown Table 5.

Table 5 Summary of Annual Electricity Cost Savings

(All figures in US $) Substation CBH 3MW Sub 3MW ESD 4MW ESD

Total annual cost $4,874,350 $4,831,516 $4,776,365 $4,760,599

Savings over

3MW Sub Option-$42,833 $0 $55,152 $70,917

Commuter Rail

A 5 mile section of a commuter rail system is simulated to

assess the feasibility of WESS as an alternative to the

traditional rectifier substation for train voltage support. The

noload voltage is at 720V and the nominal voltage 685V.

Regenerative braking is not applied for this system as most

commuter rail vehicles are incapable of braking regeneration.

Train voltage plots under different options at location MP-35

are shown in the following figures.

Train Voltages - MP32 to MP37

7-8 AM Peak Hours

MP

35-C

BH

Sub-B

34

Sub-B

36

Sub-B

32

0

100

200

300

400

500

600

700

800

32 33 34 35 36 37

Location (milepost)

Vo

ltag

e (

V)

Voltage (v)

Substations

Minimum Voltage

Figure 18: Train voltages under CBH option


7-8 AM Peak Hours

Su

b-3

5 (

New

)

Sub-3

4

Sub-3

6

Sub-3

2

0

100

200

300

400

500

600

700

800

32 33 34 35 36 37

Location (milepost)

Vo

ltag

e (

V)

Voltage (v)

Substations

Minimum Voltage

Figure 19: Train voltages under substation option


7-8 AM Peak Hours

ES

D-3

5

Sub-3

4

Sub-3

6

Sub-3

2

0

100

200

300

400

500

600

700

800

32 33 34 35 36 37

Location (milepost)

Vo

lta

ge

(V

)

Voltage (v)

Substations

Minimum Voltage

Figure 20: Train voltages under ESD option (Vc=670V)

The effect of ESD control voltage

Adjusting the control voltage (Vc) of an ESD installation will

achieve different levels of train voltage improvement. On the

other hand, high levels of voltage improvement demand higher

power ratings and larger energy capacities for the device.

Due to the distances between the ESD and the nearby

substations, the charging rate can be limited by the circuit


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resistances. Higher Vc setting can have better improvement of

train voltages. However, this needs to be balanced against the

requirement to maintain sufficient energy rate to keep the

device at desired capacity, so that there is sufficient energy

content for the next discharging cycle.

The following figure shows the load cycle under different

control voltages. The same figure also illustrates the charge

rates limited by the electrical circuits, between 1.6 and 1.8

MW.

Simulated ESD Load Cycle

-2,000

-1,500

-1,000

-500

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

7:40 AM 7:41 AM 7:42 AM 7:43 AM 7:44 AM

Time

Po

wer

(kW

)

Vc=650

Vc=660

Vc=670

Figure 21: ESD load cycle under different control voltages

The maximum charging and discharging rates and minimum

train voltages are compared in Table 6.

Table 6 ESD Rating and Capacity vs. Voltage Improvement ESD Control

VoltageVc=650 Vc=660 Vc=670

Max. MW Output 3.2 3.6 3.8

Max. kWh Usage 31.7 37.5 42.4

Minimum Train

Voltage518 529 536

Summary

This paper presented simulation results for three systems with

potential applications of a WESS as an alternative to

traditional rectifier substations for train voltage support. ESD

power ratings and energy capacities vary with the systems and

the desired levels of voltage improvement, as shown in Figure

22.

ESD Energy Capacity Requirement

3.7

12.5

14.7

31.7

42.4

0

5

10

15

20

25

30

35

40

45

Light Rail 1.5MW

ESD

Metro Rail 3MW

ESD

Metro Rail 4MW

ESD

Commuter Rail 3MW

ESD

Commuter Rail 4MW

ESD

System Types and Power Ratings

En

erg

y (

kW

h)

Figure 22: ESD energy capacity versus system type and power

rating

For two of the systems where regenerative braking is used,

there is added energy saving benefits of an ESD option. It

should be expected that the annual savings will increase in the

future as the electricity tariffs tend to go up in line with

general energy cost increases.

Acknowledgements

The authors thank Mr. Larry Goldstein, Senior Program

Officer for ACRP and TCRP, Transportation Research Board,

for his support with the study. The authors also thank all the

transit agencies, government agencies and vendors of the

APTA/EPRI Energy Storage Research Consortium for their

generous involvement and support of the project. The

simulation results presented in this paper were obtained by

using SYSTRA’s RAILSIM® Load Flow Analyzer.

References

[1] Symposium: TCRP C-75 Wayside Energy for Transit,

APTA/EPRI Energy Storage Research Consortium,

American Public Transportation Association,

Washington, DC, February 10, 2010.

[2] Energy Storage Vendor Advisory Group, APTA/EPRI

Energy Storage Research Consortium, American Public

Transportation Association, 2009.

[3] LADPW Electric Rates - Schedule A-1: Small General

Service (Effective July 1, 2009) (http://www.ladwp.com)

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