Using the ATP-EMTP simulation software to analyse and understand problems on Spoornet ...

106 Pages·2012·1.3 MB·English

Using the ATP-EMTP simulation software to analyse and
understand problems on Spoornet electric locomotives.
by
Barend Adriaan de Ru
Submitted in partial fulfilment of the requirements for the
degree
Magister in Engineering
in the
Faculty of Engineering
at the
Rand Afrikaans University
Supervisor: Prof. M. Case
November 1997
Using the ATP-EMTP simulation software to
analyse and understand problems on
Spoornet electric locomotives.
Abstract
Spoornet currently has a fleet of more than 1500 electric locomotives in
service. The majority of electric locomotives are resistor controlled but there
are many chopper as well as thyristor controlled locomotives which all
incorporate direct current (dc) traction motors. In recent years Spoornet has
also bought locomotives employing alternating current (ac) traction motors.
Because locomotives are very expensive and the running costs are high it is
important that these locomotives must be available and reliable. Most of the
newer generation locomotives, which are the semiconductor controlled
locomotives, must be in service for at least another 20 years.
The availability and reliability are often influenced by delayed design
problems as well as problems arising due to changes in the total system
configuration. One way of solving these problems, or at least understanding
them, is by employing computer simulations.
The availability and reliability can also be improved by using new
technologies which were not originally employed on the locomotives. By
doing computer simulations the optimal solution can be obtained when
introducing new technologies on the locomotive.
A good example of this type of application within Spoornet is given in [6],
where simulation models for high technology locomotives were developed
which were suitable to be used in the assessment of electromagnetic
compatibility between modern power electronic locomotives and the railway
signaling system. However, these models are also suited to be used in other
applications. These models make use of the ATP-EMTP simulation program.
Contents
CHAPTER 1 (cid:9) 6
BASIC DESIGN CONCEPTS OF AN ELECTRIC LOCOMOTIVE.(cid:9) 6
1 INTRODUCTION. (cid:9) 6
2 THE ELECTRICAL TRACTION SYSTEM. (cid:9) 7
2.1 Electrification. (cid:9) 7
2.2 The electric locomotive. (cid:9) 8
2.2.1 The traction motors. (cid:9) 10
2.2.2 Power Converters. (cid:9) 11
2.2.3 The control system. (cid:9) 12
3 DESIGN SPECIFICATIONS. (cid:9) 12
3.1 The Class 92 Tunnel Train. (cid:9) 13
3.1.1 Basic Specifications. (cid:9) 13
3.1.2 Designed Values. (cid:9) 13
3.2 The Class 9E locomotive. (cid:9) 14
3.2.1 Basic Specifications. (cid:9) 14
3.2.2 Basic Tractive Effort Calculations. (cid:9) 14
CHAPTER 2 (cid:9) 17
USING THE ELECTROMAGNETIC TRANSIENT PROGRAM IN TRACTION
APPLICATIONS (cid:9) 17
1 BACKGROUND. (cid:9) 17
2 SIMULATION EXAMPLE.(cid:9) 17
3 DATA BASED MODULES (cid:9) 18
4 USING MODELS AND TACS (cid:9) 20
5 MODELING OF MOTORS (cid:9) 21
5.1 The primitive machine (cid:9) 21
5.2 Simulation of machines with the ATP-EMTP (cid:9) 22
6 USING THE ATP-EMTP TO SIMULATE ELECTRICAL CONVERTERS. (cid:9) 24
7 NUMERICAL OSCILLATIONS. (cid:9) 25
CHAPTER 3 (cid:9) 26
SIMULATION COMPONENTS OF SPOORNET ELECTRIC LOCOMOTIVES. 26
1 INTRODUCTION. (cid:9) 26
2 DESCRIPTION OF A THYRISTOR CONTROLLED LOCOMOTIVE. (cid:9) 27
3 THYRISTOR CONTROLLED LOCOMOTIVE SIMULATION MODEL. (cid:9) 28
3.1. The Transformer. (cid:9) 28
3.1.1 The classical transformer model (cid:9) 28
3.1.2 A high frequency transformer model. (cid:9) 32
3.2 The Double Bridge Half Controlled Rectifier. (cid:9) 36
4 SIMULATION OF THE TRACTION MOTORS. (cid:9) 37
4.1 Traction motor models. (cid:9) 37
4.2 The mechanical system. (cid:9) 39
4.3 The Control System. (cid:9) 40
CHAPTER 4 (cid:9) 42
PRACTICAL APPLICATION AND FUTURE WORK.(cid:9) 42
1 INTRODUCTION. (cid:9) 42
2 THYRISTOR CONTROLLED LOCOMOTIVE. (cid:9) 42
2.1 Typical results. (cid:9) 42
2.2 Power factor correction circuits. (cid:9) 45
3 MOTOR SIMULATION RESULTS. (cid:9) 45
4 HIGH FREQUENCY TRANSFORMER MODELING (cid:9) 48
5 OTHER PROPOSED MODELS (cid:9) 50
6 LEARNING TOOL (cid:9) 52
7 ELECTROMAGNETIC COMPATIBILITY (cid:9) 52
Chapter 1
Basic Design Concepts of an Electric Locomotive.
1 (cid:9) Introduction.
The first railway engine ever was built by Richard Trevithick in the beginning
of the 19th century. Less than fifty years later, in 1842, the first true electric
locomotive was built by Robert Davidson and employed on the Glasgow-
Edinburg line [1]. Since then railway engines have undergone many
developments, and in many respects played a leading role in industry. For the
first part of this century up to the early 1970's direct current (dc) traction
motors were the accepted norm because of their versatility having a wide
variety of volt ampere or speed-torque characteristics. These motors were
mainly controlled, using resistor-switching controls. From the mid 1960's
thyristor controls were introduced in electric locomotives. Semiconductor
devices were now being developed at an ever-increasing rate, and thyristors
were replaced by gate turn-on thyristors (GTO's). Computer technology also
developed at a rapid rate since the 1970's, which made it more and more
possible to design variable speed drive systems for alternating current
motors. These variable speed drive systems, also employing integrated gate
bipolar transistor (IGBT) technology, are now very common in the traction and
other industries, and have been for a few years.
These developments were also implemented in South Africa, with most of the
technology coming from Europe and Japan. The first type main line electric
locomotive to be employed in South Africa was the class lE locomotive. It
was introduced into traffic in 1924 [2]. From the 1950's up to the 1970's,
hundreds of 3kV resistor controlled dc trains were supplied to the South
African Transport Service (now called Spoornet). The first thyristor controlled
alternating (ac) locomotives were introduced in 1976 [3]. This was the class
7E locomotive. South Africa also bought several different classes of chopper
controlled locomotives. In the 1980's induction motors were used for the first
time in traction on the 38 class diesel-electric locomotives, and thereafter on
the class 14E locomotives.
Spoornet currently has a fleet of more than 1500 electric locomotives in
6
service. The majority of electric locomotives are resistor controlled but there
are many chopper as well as thyristor controlled locomotives which all
incorporate dc traction motors. There are also a few inverter controlled
locomotives incorporating induction motors.
This chapter gives a basic introduction on the design concepts of electric
locomotives. Different drive systems used in Spoornet are briefly discussed,
as well as traction motor mechanical system interaction and control system
strategy. Basic specifications on some locomotives used in other parts of the
world as well as South-Africa are also discussed.
2 (cid:9) The electrical traction system.
The basic electrical traction system consists of the electrification system,
which includes the supply, contact wire and rail as shown in figure 1, and the
locomotive.
Contact wire
Rail
Figure 1 Basic traction system
The ideal computer model would take into account the whole electric traction
system incorporating all the effects of all the trains on the line and different
switching operations. This will require enormous computing power, taking into
account the very short time periods (due to quick switching transients) and
also the very long time periods (such as accelerating a locomotive with a
loaded train, to a specific speed). Therefore it makes more sense to break
any simulation down into manageable parts.
An example of the simulations of a basic traction system is given in [8,9].
2.1 (cid:9) Electrification.
Throughout the world there are different standards of electrification. Most
countries have more than one system. Typical systems in use are 1.5kV dc,
3kV dc, 15kV 16 and 2/3 Hz ac and 25kV 50Hz ac. In Europe a high
percentage of railroads are electrified. A summary of the electrification is
given in table 1 [10,16].
7
(cid:9)
(cid:9)
3kV dc 1.5 kV dc 15kV 16 2/3 Hz 25kV 50Hz
T
Belgium Netherlands Germany Portugal (cid:9) Bulgaria
Italy South of Switzerland United (cid:9) Romania
Spain France Austria Kingdom (cid:9) Croatia
Poland Norway North of (cid:9) Servia
Czechoslovakia Sweden France (cid:9) Finland
Slovenia Hungary (cid:9) Part of
Part of Russia Russia
Table 1 Electrification in Europe
In the United Kingdom a 3rd rail 750V dc system is also used. A typical
arrangement for a 25kV ac electrification system is shown in figure 2 [26].
88kV 3 Phase 50Hz
. (cid:9) •(cid:9)
r' (cid:9) i __=.-Circuit Breaker
- (cid:9)
r Line Break
[1
25kV 50Hzie,/_ (cid:9) -_-(cid:9)/ ,_.:.,,,,-'/' --/'-• (cid:9)
Figure 2 Typical 25kV ac electrification system
In the America's a low percentage of railroads are electrified. In Southern
Africa only 3 countries have electrified railroads namely Zambia * , Zimbabwe
and South Africa. In South Africa almost 10 000 km of railroad are electrified
with 3kV dc, 25kV 50Hz ac or 50kV 50Hz ac systems [10].
2.2 (cid:9) The electric locomotive.
An electric locomotive is an electromechanical energy converter. Electrical
energy is converted to mechanical energy when the locomotive is powering.
Mechanical energy can also be converted to electrical energy when the
locomotive is moving and electrical brakes are applied.
This energy conversion is shown in figure 3. The electrical input power is
equal to Vijne x /me. The input power is converted to mechanical output power.
The output power is equal to Force x Speed. The Force could either be a
It is not known whether this line is in operation
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pulling force, TE (Tractive Effort), or a braking force, BE (Braking Effort).
TE
--> TE/BE (cid:9)
Vlines-) Speed
---> Speed BE7
Powering
Speed
Braking
Figure 3 Electromagnetic Energy Conversion of a Locomotive
This figure also shows the Tractive Effort and Braking Effort curves. These
curves are typical basic design curves for a locomotive. The following basic
equations apply for powering and braking respectively (if it is assumed that all
the power is transferred back to the line).
TE x Speed + (Electrical Loss + Mechanical Loss)
'line x I line =
(1)
V BE x Speed — (Electrical Loss + Mechanical Loss)
line x I line =
The electrical system of an electric locomotive can be broken up into different
components. The main components are the following
Traction motors which do the electrical to mechanical energy
conversion
Power converters and power supply, supplying the traction motors
with the correct input power
Control system which control the power converters according to the
altered driver demand
A generalised block diagram of the implementation of these basic
components on Spoornet locomotives is shown in figure 4.
Motor with
Power (cid:9) Mechanica
Suppl (cid:9) Load
Driver (cid:9) Referance Control Power
Demand Convertor
Figure 4 Generalised Block Diagram of Spoornet
Electric Locomotives.
9
(cid:9)
Since the introduction of the first electric locomotive, all these components
have undergone a great deal of development, to keep up with modern trends
like speed, higher efficiency, heavier freight and so forth.
2.2.1 The traction motors.
The direct current (dc) motor has been the workhorse of traction for many
years. With the introduction of semiconductor technology and improvement in
microprocessor control, induction motors with variable speed drive systems
became the norm. Synchronous motors have also been used in traction, but
as with dc motors the maintenance cost, among other problems, is still high
compared to induction motors.
Before selecting a traction motor and power converter for a certain traction
application, load requirements must be available. These are for example the
maximum load to be hauled, the speed range and the maximum speed. In
traction applications these values are summarized in tractive effort and
braking effort curves, as shown in figure 3.
A motor and load system is shown in figure 5.
r6
II

Motor (cid:9)
(cid:9) y El El (I
) • .1 ruL TL
Jrn B,„ (cid:9) (01",,, (cid:9) 'i's'
PI ,( IVI
Load (cid:9) JL BL
1
Figure 5 Motor with load
The motor and load are coupled using a gear mechanism with the torque's on
both sides of the gears related as (assuming that the efficiency of the gear is
100%)
= (cid:9) = NcT, (2)
n,
where nn, and nL are the number of teeth on the motor and load side
respectively [17].
10