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IICPE.2016.8079493

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Conventional Indian Railways and the Advanced
Transportation Systems: A Comparative Review
V. Shirish Murty
Shailendra Jain
Student Member, IEEE
Research Scholar, MANIT, Bhopal
murty.shirish@gmail.com
Senior Member, IEEE
Prof. EE. Dept., MANIT, Bhopal
sjain68@gmail.com
Abstract— This paper presents the concepts of conventional
electric traction system and the advanced transportation systems
adopted for research and commercialization in Indian railways.
A comparative study is presented on Conventional systems,
Metro transit, Pendolino trains, Talgo transit system and Maglev
technologies. The principle requirements, control mechanisms,
merits and demerits of electromagnetic schemes of maglev
systems are also presented. Static and dynamic model
explanation is given to propose the control mechanism for the
development of High Speed Transit System with Maglev effect.
Keywords— Electric traction system, Metro transit, Pendolino
trains, Talgo Transit system, Magnetic Levitation, High speed
transit system, Linear motors.
I.
INTRODUCTION
With the increase in traffic density in the developing
countries, like India, the transit systems like automobiles and
air services are unable to provide the required load of mass
transit. In order to meet the demand, the transit system should
be convenient, high speed, eco friendly, maintenance free,
reliable, safe and suited to bulk transportation [1,2]. Reduction
of transport associated pollution, and a more comfortable and
efficient transportation in respect of both the ride quality and
improved speed, is the primary motivation. A novel
technology that brings all the advantages of high speed
transportation system, such as the Maglev without the
exorbitant cost is the demand of the scenario.
In earlier days, direct current motors were used. Bad
commutation, high initial and maintenance cost has became the
major disadvantages of the DC motors. Later on AC induction
machines were launched in the field of traction. Due to their
fixed speed characteristics, they were difficult to apply for
traction applications [2].
One of the best solutions to fulfil the above requirements is
Magnetic Levitation (Maglev) trains [1,5]. Conventional
railway locomotives moves by utilising friction between rails
and wheels but the Maglev trains have electromagnets in place
of wheels. It levitates on the guideway and produces
propulsion force electromechanically without having any
physical contact [2].
In this paper, the concepts of conventional electric traction
system and the advanced transportation systems such as Metro
transit, Talgo system and High speed Maglev transit system,
978-1-5090-4530-3/16/$31.00 ©2016 IEEE
have been presented. The suitability of such advanced transit
systems for research and commercialization in Indian railways
has also been discussed. A study on the static and dynamic
modeling of the locomotive which will be useful for the
implementation on high speed transit systems is analyzed. The
need of linear motors in practical scenario and their various
practical applications are also included. Using finite element
method the magnetic performance of the proposed Linear
motor is demonstrated.
II.
CONVENTIONAL INDIAN RAILWAYS
The Indian rail is considered to be the single largest user of
the electrical power in the country. It has one of the largest rail
networks in the world [2-4]. It has a large fleet of trains, which
includes diesel and electric engines, and a requirement of a
high capacity of transportation for passengers and goods. Its
passage through huge sections of forests and its impact
adversely affects these forests [4]. Curbing the consumption of
fuel per ton per mile by the railways, would have substantial
environmental impact and would be single greatest contributor
for energy conservation.
There are many factors which hurdles in increasing the
speed of trains [3,4]. These are as follows1. Old technology and infrastructure, which are still using
track building and other subtle foundation of the
infrastructure.
2. Poor coupling technique which decreases the stability and
permit of high speed transportation.
3. Longer length of trains to cater large number of passengers
and inability of heavy loading of goods in transportation.
4. Unreliable tracks, in some sections trains can’t even touch
100 km/h speed falling against the dream of achieving 200250 km/h.
5. Economy does not support investment in new
infrastructure.
6. Potential commuters constitute very less percentage as
compared to current number.
7. Large distance between major cities.
Our present technology is sufficient to cross the threshold
of 200 km/hr, as seen on Delhi-Agra section [3-5]. The system
can be made more reliable by having solid track foundation,
improved coupling system and by decreasing length of trains.
A detailed scenario of the electric traction system in Indian
railways is explained in the next section.
A. Electric traction system
Electric locomotive is a vehicle that can move along rails
and push or pull a train attached to it using electric power
drawn from overhead lines. This power is extracted from
overhead lines and then transformed and modified before
feeding it to traction motors.
compared to AC motors [1]. But, with an advent of highly
robust and flexible 3 phase AC machines , the DC motors are
almost replaced with AC motors [4,5]. Locomotives uses 3
phase induction motors, though the speed torque curve of
induction motor is flat, but better speed control is achieved by
supplying A.C. of varying frequency as shown in Fig.1.
B. Metro
Trains which functions as a means of transportation within
a particular city are generally termed as Metro trains, which is
shown in Fig. 2. They are faster and are light weight plus have
high more horsepower per ton (15 kW/ton) as compared to
conventional (5-10 kW/ton) [6]. Base of track is also solid
which results in decreased vibrations and stable and smooth
ride. It employs polyphase induction motor for traction.
Fig. 1 Conventional Electric railway locomotive [5]
For modifying, the present system, it uses a number of
components which carry out the complicated processes of
conversion, reconversion, smoothening and transformation of
the current, voltage and frequency [5]. The parameters of
locos WAP 5, WAP7 and WAG9 are shown below in Table 1.
Table 1: Mechanical and Electrical parameters of Locomotives [2]
PARAMETER
WAP5
WAP 7
WAG9
GEAR RATIO
1:3.65
1:3.6
1:5.133
WEIGHT
78 TONNE
123 TONNE
123 TONNE
OHE
VOLTAGE
NORMAL
MAX.
MIN.
25kV
30kV
17.5kV
FREQUENCY
NORMAL
MAX.
MIN.
50 Hz
55 Hz
45 Hz
NO. Of
TRACTION
MOTORS
4
VOLTAGE TO
TRACTION
MOTOR
6
Fig. 2 Metro transit system [6]
The requirement of a train working as metro is high
starting torque, high acceleration and high deceleration. It
should start faster, accelerate fast to reach track speed and
then decelerate fast to stop at the station. As the distance
between two consecutive stations is around one km, so slow
start or slow braking is not affordable. For this purpose, metro
uses two systems:
1. Distributive traction
6
2180V
POWER OF
TRACTION
MOTOR
1536 hp
1156 hp
1156 hp
TRACTIVE
EFFORT
258 kN
322.6 KN
458kN
BRAKING
EFFORT
160kN
182 KN
260 kN
TOTAL HP
5440 hp
6120 hp
6120 hp
MAX SPEED
160 km/hr
130 km/hr
100 km/hr
In earlier locos (WAP 5/ WAP 7/ WAG 9), traction motors
driving the axles were DC motors. DC motors were initially
used as they provide far superior speed and torque control
In this locomotive units are installed under the bogies of
the train. Either each or every other bogie has its propulsion
unit. Generally, 4 wheels of the coach are powered and 4 are
unpowered, therefore the complete train is started with all the
propulsion units working in unity. Thus provide high starting
torque, high acceleration and high braking capacity [6, 7].
This system can be used to achieve high speed also; in fact,
most of the high speed trains around the world uses
distributive traction (other than maglev).
2.
Electrical Multiple Units (EMU)
In India, metros work on this system. Here multiple units
are connected in a single metro train. Usually every metro
train consists of 3-4 EMU’s for obtaining high torque for the
propulsion of the locomotive [6].
Disadvantages in operation as conventional trains:
1. A fleet of MU cars cost more than conventional
locomotive to maintain [7].
2.
3.
4.
Have more parts means more maintenance and
inspection.
Bigger maintenance sheds required plus time
consumption would be more as compared to single
locomotive.
They are not that effective on long routes.
With an increase in demand of high speed mass transit of a
nation, Talgo hybrid train has arrived as an ideal solution. It
can run on both electrified and non-electrified lines, and
within electrified lines both AC and DC supply is supported.
Moreover propulsion bogies have been designed to allow
dynamic gauge change.
III.
The new traction chain is adapted in two ways; one side
considers the traction locomotives to be able to operate in
diesel or electric mode, which also possesses the ability to
detect and translate DC and AC supply during a change in
supply system [8-10]. On the other side, the innovation in
bogie design with adapted motors and gear boxes allows
dynamic gauge change of the train [9,10]. This enables Talgo
trains to adapt every situation with its advanced integrated
system and fulfill the measures of safety and reliability.
ADVANCED TRANSPORTATION SYSTEMS
A. Pendolino Trains
The word ‘Pendolino’ is derived from pendulum. It is an
Italian family of trains which runs in Italy, Spain, Portugal,
Russian federation, and U.K. [8]. The high speed travel
through Pendolino is still under research stage in Indian
Railway industry. It has to go through a compatibility check
on Indian railway tracks, after which, It may proceed for test
runs. A geometric design of Pendolino is shown in Fig. 3.
These trains are already being tested in the Spanish railway
network, with a highly successful result, and will be shortly
placed in commercial service, proving that the model is
exportable to any part of the world, including India. A model
of train imported for India Railways [10] is shown in Fig. 4.
Fig. 3 Pendolino transit system [9]
In these trains, a secondary suspension is provided between
the bogie and the passenger car with the help of
electromechanical actuators. Accelerometers are placed on
each coach, which senses the lateral acceleration and provides
the input to processing unit. These high speed controllers
gives command to actuators resulting in tilting of the vehicle
in the direction of curvature of the track [8,9].
The effect of lateral acceleration is not completely
cancelled, as it may create nausea or motion sickness to the
passengers sitting inside the train. This effect occurs because
of the different inputs from eyes and body, where at one end
the eye informs the brain that train is tilting on a curvature
track, but on the other end the body informs that nothing is
happening, therefore the passengers may not be able to cope
up with this dual response, and hence produces a sense of
motion. Due to this, only 70-80% effect is cancelled out [9].
B. Talgo Trains
Talgo Hybrid Train is a Spanish construction. It is an alltrack train built up with an aim of providing maximum
interoperability, eliminating the limitations of the
conventional railway system, such as variation in gauge,
supply feeds and speed constraints on the curvature. Since a
single train is capable enough to operate on almost any
condition, it is accepted by many countries as a convenient
means of transportation [10].
Fig. 4 Talgo transit system [10]
C. Magnetic Levitation Technology
It is a method by which an object is suspended with no
support other than magnetic fields. Magnetic force is used to
counteract the effects of the gravitational acceleration and any
other acceleration [11]. With maglev, a vehicle travels along a
guide way using magnets to create both levitation and
propulsion, which is shown below in Fig. 5.
Propulsion
Track
N
S
N
S
Car-4Car-3
S
Train
N
N
Car-2Car-1
Train
N
S
N
Track
S
Train
N
S
S
S
N
S S
NN
N
S
Track
Propulsion
Levitation
Guidance
Fig. 5 Principles of Maglev technology [6]
Combination of systems required for successful levitation
and control of all 6 axes (3 translational, 3 rotational) in such a
way that it provides at least one stable axis for the system to
levitate and stabilize other axes [12]. The various methods
used for stable magnetic levitation are as follows-
ƒ Servomechanism
An on-off mechanism is used in electromagnets for
producing the levitation [11]. The electromagnet attracts the
magnetic surface laid on the ground. When the electromagnet
is switched on, the energization of current in the coils pulls it
towards the magnetic surface. As soon as, the electromagnet is
switched off, the mutual field coupling breaks and the distance
between them becomes less than 10 cm. This gap is
maintained using servo mechanism.
ƒ Induced currents
Induced current is another method to produce levitation.
The principle behind the production of induced currents is
Repulsion due to Lenz’s law. It can be achieved by relative
motion (magnet dropped in copper tube), or by oscillating
electromagnetic fields [12].
ƒ Diamagnetic levitation
It uses the property of diamagnetism i.e. object create a
magnetic field opposite to an externally applied magnetic
field. Mechanical constraint is used in levitation stability. If a
magnetic surface is repelling other magnet, characterizing
same polarities, it will try to get attached, but some constraint
is provided in terms of displacement for maintaining the gap.
ƒ Superconductors
They are considered as perfect diamagnets, but require low
temperature for operation. It uses a series of superconducting
coils for the production of levitation force between the coils
and the magnetic surface. A heavy cryogenic support is
required to generate the force of levitation [11-13].
The block diagram of the maglev system enabling
levitation, propulsion and guidance is shown in Fig.6.
V.
FACTORS AGAINST MAGLEV (INCLUDING ITS
COMPATIBILITY TO INDIAN ECONOMY) [12,13]
1. High initial constructional cost makes it a costlier system
to be adopted by a developing country.
2. Use of rare earth magnets, which have stronger magnetic
field than ordinary ferrite or alnico, increasing its
construction costs.
3. In view of the fact that presently in Indian railways, 7080% revenue from passengers comes from sleeper and
general class, there doesn’t seems a promising future of
maglev.
4. Present infrastructure does not even support complete use
of durantos or rajdhanis on all sections. Thus we have to
build separate corridor which demands huge infrastructure.
5. These systems need high maintenance and high precision
in operation.
VI.
TYPES OF MAGLEV SYSTEMS
There are two existing technologies of Maglev trains,
Electro-Magnetic Suspension (EMS) and Electro-Dynamic
Suspension (EDS), which use servo-controlled electromagnets
and cryogenically cooled superconducting magnets,
respectively [11-15]. EMS and EDS technologies are used in
German Trans Rapid and Japanese Yamanashi trains
respectively, operating at speeds of about 500 km/hr [11].
They are described as followsA. Electromagnetic Suspension (EMS)
Shanghai Maglev works on the principle of EMS [11]. In
EMS, the current to electromagnets is continually altered to
change the strength of the magnetic field and allows a stable
levitation to occur. It uses the property of attraction of
opposite poles of magnet.
In this system train is lifted from beneath the track. There
are iron core electromagnets in carriages and ferromagnetic
rails underside of the guideways. Propulsion is done with the
help of linear synchronous motor [12].
Fig. 6 Block diagram of conventional maglev system
IV.
ADVANTAGES OF MAGLEV OVER CONVENTIONAL
TRAINS [11-14]
1. Significant reduction in wear and tear of the rolling stock.
2. Reduced size of the locomotive as well as linear motors.
3. Little or no pollution, less noisy. So, they are very suitable
for urban as well as sub urban areas.
4. Ability to move the goods-wagons and the passenger
coaches at a comparative higher speed, resulting into
multifold increase of the system’s carrying capacity.
5. Increases the stability and allows higher permissible speeds
because of the virtual gauge width over the complete
surface of the coaches.
6. Smooth and comfortable rides, with a reduction of
bumping on the seats of the passengers.
Pros: Longer lifetime, lower operating costs, faster operation,
low magnetic exposure.
Cons: Expensive computer systems for monitoring magnetic
strength.
B. Electrodynamic Suspension (EDS)
Japanese Maglev system follows the principle of Magnetic
Repulsion for establishing the Electrodynamic mechanism
[11]. Japan is working on the concept of Maglev
transportation since 1962. HSST Linimo (Linear motor
maglev) and SC (Superconducting) Maglev are based on
principle of magnetic repulsion between the track and the cars
[12-14]. This system uses an electro dynamic suspension
(EDS) mechanism. Superconducting magnets are installed in
the train’s bogies which repels the coils on the guide way.
It runs on rubber wheels initially up to 100-150 km/h
speed. Below this speed, the induced current developed is not
sufficient to lift the train. When the vehicle attains a certain
speed, an electrical potential is developed between the
superconducting magnets and the coils, and the current flows
in such a way that it opposes the effect producing it (Lenz’s
law), tries to centre the magnetic field and lift the train [13].
Pros: Longer lifetime, lower operating costs, faster and
reliable operation, safer during power outage.
Cons: Significant incremental cost for additional cryogenic
support required for cooling superconductive magnets.
VII.
LINEAR MOTORS
Linear motors are the extended form of conventional
rotary motors as shown in Fig. 7. Rotary motors produce
torque circularly in rotor whereas linear motors give force
linearly in translator. Depending on the usage, linear motors
are categorized into high acceleration motors and low
acceleration motors. High acceleration motors are used in the
field of spacecraft propulsion, weapon firing, and
hypervelocity collisions whereas, Low acceleration motors are
used in the area of Maglev trains and ground based
transportation applications [16, 17].
VIII.
Permanent Magnets are emerging as a promising material
in the production of high field strength for the development of
High Speed Transit System. Linear motors is emerging for
many applications such as rapid transit systems, amusement
rides, automatic closing doors, lift applications, aircraft
launching etc. With the advent of better power controllers and
favorable cost, it is finding huge response in automation
industries as well as in high speed transit applications. These
can be used to reduce the cost of the system and to make the
system compact, highly reliable and maintenance free.
REFERENCES
[1]
[2]
[3]
[4]
Fig. 7 Conversion from conventional motor to linear motor [17]
Depending on the working principle, linear motors are
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and Linear Switched Reluctance Motors. Due to high cost and
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applications. LIM, LSM, LSRM are used in various
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Reluctance Motor is shown in Fig, 8
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
Fig. 8 Linear Reluctance motor for maglev application
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