1. APPLICATIONS OF HIGH TEMPERATURE SUPERCONDUCTOR AND
ITS BENEFITS IN POWER SYSTEM TRANSMISSION
A MINI PROJECT
PRESENTED IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE
COURSE EEE492
IN
DEPARTMENT OF ELECTRICAL ENGINEERING, FACULTY OF ENGINEERING,
UNIVERSITY OF NIGERIA NSUKKA
BY
NWOKOLO, ERIC ONYEKACHI
2008/158226
OCTOBER, 2012

2. CERTIFICATION PAGE
This is to certify that I am responsible for the work submitted in this mini
project, and the original work submitted therein has not been submitted to this
department for the course EEE 492
NWOKOLO, ERIC ONYEKACHI
2008/158226
DATE: -------------------------------------

3. APPROVAL PAGE
This mini project has been approved by the Department of Electrical
Engineering, faculty of Engineering, University of Nigeria, Nsukka.
BY
---------------------------------- --------------------------------
Engr. M. J. MBUNWE Date
(Project supervisor)
---------------------------------- --------------------------------
Engr. C. A. NWOSU Date
(Mini Project Co-ordinator)
……………………………… ………………………….
ENGR. DR. B.O. ANYAKA Date
(Head of Department)

4. TITLE PAGE
APPLICATIONS OF HIGH TEMPERATURE SUPERCONDUCTOR AND
ITS BENEFITS IN POWER SYSTEM TRANSMISSION

5. DEDICATION
This work is dedicated to the almighty God that gives me the strength to
write this work and the inspiration he endowed on me in the course of writing
this mini project. Also it is dedicated to the entire family of Mr. and Mrs.
Nwokolo B.I. for their immense support in the course of writing this work both
financially and otherwise. More so, it is dedicated to my friends, well wishers
who have in one way or the other helped me in organizing and making this work
successful.

6. ACKNOWLEGMENTS
First of all I recognize the strength and wisdom God has bestowed on me
to see this work (mini project) come to reality. A work of this nature cannot be
complete without the supports receive from people of good will. I owe a lot to
those noble men and women. Among them is my project supervisor, Engr M.J.
Mbunwe, a highly principled somebody. Gratitude is a debt we owe and remains
one that must be settled. My gratitude also goes to scholars I made reference to
their work.
I also thank my father, Mr. Nwokolo B.I. and my mother, Mrs. Nwokolo
R., my elder sister Mrs. Ozor N.V., onyinye, chidera, udoka (my sisters) and
ikechukwu (my younger brother) for their understanding and patience in neglect
of family affairs during this research. Thanks a million times.

7. ABSTRACT
An aging and inadequate power grid is now widely seen as among the greatest
obstacles to efforts to restructure power system markets. In light of new and
intensifying pressures on the nation’s power infrastructure, industry and policy
leaders are looking to new technology solutions to increase the capacity and
flexibility of the grid without further raising system voltages. High Temperature
Superconductor (HTS) cable is regarded as one of the most promising new
technologies to address these issues. Among HTS cable designs, one in particular
– shielded cold dielectric cable – offers performance advantages particularly well
suited to today’s siting, reliability and performance challenges. Shielded cold
dielectric HTS transmission cables feature very close spacing between the
conductor and shield layers of wire in a coaxial cable. This close spacing result in
several advantages: lower electrical losses; the virtual elimination of stray EMF;
and significantly lower impedance than conventional cables and lines. Cables
suited for distribution-voltage, high-current applications exhibit similar benefits;
including the HTS cables design which make it possible to control power flows
over HTS circuits .

8. TABLE OF CONTENTS
Certification page…………………………………………………….. ii
Approval page………………………………………………………… iii
Title page……………………………………………………………….. iv
Dedication……………………………………………………………… v
Acknowledgement……………………………………………………… vi
Abstract………………………………………………………………….. vii
Table of contents……………………………………………………… viii
CHAPTER ONE:
1.0Introduction…………………………………………………………. 1
1.1Purpose of the study………………………………………………… 3
1.2Statement of the problem…………………………………………… 3
1.3Limitation of the study……………………………………………. 4
CHAPTER TWO:
2.0 Literature review…………………………………………………… 5
2.1Superconductor material……………………………………………… 8
2.2 Special Properties of super conductor ………………………………. 9
2.3 High temperature super conductor cable architectures……………… 10
2.4Comparison between Superconductor and Other Conductors……….. 12
CHAPTER THREE:
3.0 Methodology……………………………………………………… 13
3.1 Area of study……………………………………………………… 13

9. 3.2 Instrument for data collection…………………………………….. 13
3.3 Methods of data collection……………………………………….. 13
3.4 Methods of data analysis…………………………………………. 14
3.5Applications of high temperature superconductor in power system…… 14
3.6Benefits of superconductors in power system…………………………. 22
CHAPTER FOUR
4.0 Discussion…………………………………………………………..... 28
4.1 Outcome of case studies……………………………………………… 29
4.2 Analysis of the research………………………………………………. 33
4.3 Cost of the research …………………………………………………. 37
CHAPTER FIVE
5.1 Conclusions…………………………………………………………… 39
5.2 Recommendations …………………………………………………… 40
REFERENCES.
APPENDIXES.

10. CHAPTER ONE
1.0 INTRODUCTION
Superconductivity is a unique and powerful phenomenon of nature. Nearly
a century after its first discovery, its full commercial potential is just beginning to
be exploited. It is widely regarded as one of the great scientific discoveries of the
20th Century. This miraculous property causes certain materials, at low
temperatures, to lose nearly all resistance to the flow of electricity [1]. This state
of approximately zero loss enables a range of innovative technology applications.
At the dawn of the 21st century, superconductivity forms the basis for new
commercial products that are transforming our economy and daily life.
Superconductor-based products are extremely environmentally friendly compared
to their conventional counterparts [1]. They generate no greenhouse gases and are
cooled by non-flammable liquid nitrogen (nitrogen comprises 80% of our
atmosphere) as opposed to conventional oil coolants that are both flammable and
toxic. They are also typically at least 50% smaller and lighter than equivalent
conventional units which translate into economic incentives. These benefits have
given rise to the ongoing development of many new applications in the electric
power system sector.
However, superconductors enable a variety of applications to aid our aging
and heavily burdened electric power infrastructure - for example, in generators,
transformers, underground cables, synchronous condensers and fault current

11. limiters. The high power density and electrical efficiency of superconductor wire
results in highly compact, powerful devices and systems that are more reliable,
efficient, and environmentally harmless [1].
More so, an aging and inadequate power grid is now widely seen among
the greatest obstacles to restructure power markets. Utilities and users face
several converging pressures, including steady load growth, unplanned additions
of new distribution capacity, rising reliability requirements, and stringent barriers
to sitting new facilities, particularly extra-high voltage (EHV) equipment [2]. In
light of persistent challenges to proposals for conventional grid expansion, and
the recognition that industry reforms cannot succeed without renewed grid
investment, new technologies that can increase the attention are now becoming in
view. Interest in new, low-profile technologies to solve grid reliability problems
intensified as a result of frequent blackout in the nation which highlighted the
importance of power system reliability and the extent to which the margin for
error in this critical system has been eroded by falling investment and other
factors [2].
Moreover, one of the technologies with the greatest promise to address the
problem of power system is the high capacity, high-temperature superconductor
(HTS) cable which is capable of serving very large power requirements at
medium and high-voltage ratings. Over the past decade, several HTS cable
designs have been developed and demonstrated. All of these cables have a much
higher power density than copper-based cables or other convectional conductor.

12. Hence, because they are actively cooled and thermally independent of the
surrounding environment, they can be fit into more compact installations than
conventional copper cables, without concern for spacing or special backfill
materials to assure dissipation of heat. This advantage reduces environmental
impacts and enables compact cable installations with three to five times more
enough than conventional circuits at the same or lower voltage [3]. In addition,
HTS cables exhibit much lower resistive losses (approximately zero) than occur
with conventional copper or aluminum conductors. Despite these similarities,
important distinctions do exist among the various HTS cable designs.
1.1 PURPOSE OF THE STUDY
There are many applications of high temperature superconductor which
include: electric power, transportation, medicine, industry, communication, and
Scientific Research. In this work, the purpose or goal of this study is to find out
application of high temperature superconductors and its benefits in power system
transmission.
1.2 STATEMENT OF THE PROBLEM
An aging and inadequate power grid is now widely seen among the
greatest obstacles in efforts to restructure power system markets. In light of new
and intensifying pressures on the nation’s power infrastructure, industry and
policy leaders are looking to new technology solutions to increase the capacity
and flexibility of the grid. Thus, the need to know the applications of High

13. Temperature Superconductor (HTS) cable since it is regarded as one of the most
promising new technologies to address these issues in power system
transmission. These problems of power system include: overloading of the
cables, problem of siting new lines, issue of moving power safely and
efficiently, carbon free electric power, instability of power, unacceptably high
power surges.
1.3 LIMITATION OF THE STUDY
There are many applications of high temperature superconductor and their
benefits in different fields as a result of its unique characteristics. In electronic,
the low microwave losses of HTS thin films enables the coupling of an
unprecedentedly large number of resonators to microwave filter devices with
much sharper frequency characteristics than conventional compact filters, in
military, in aircraft electronics, for better rejection of interference noise in aircraft
radar systems, in mobile phone communication systems, HTS microwave filter
subsystems are already a commercially available solution for problematic radio
reception situations, as in sensors, magnets, Power applications [1]. Hence, our
study here will be limited on the application of high temperature superconductor
and their benefits in power system transmission.

14. CHAPTER TWO
2.0 LITERATURE REVIEW
In 1911, H. K. Onnes, a Dutch physicist, discovered superconductivity by
cooling mercury metal to extremely low temperature and observing that the metal
exhibited approximately zero resistance to electric current. Prior to 1973 many
other metals and metal alloys were found to be superconductors at temperatures
below -249.8oC [1]. These became known as Low Temperature Superconductor
(LTS) materials. Since the 1960s a Niobium-Titanium (Ni-Ti) alloy has been the
material of choice for commercial superconducting magnets. More recently, a
brittle Niobium-Tin inter-metallic material emerged as an excellent alternative to
achieve even higher magnetic field strength. In 1986, J. G. Bednorz and K. A.
Muller discovered oxide based ceramic materials that demonstrated
superconducting properties as high as -238oC. This was quickly followed in early
1997 by the announcement by C. W. Chu of a cuprate superconductor
functioning above -196oC the boiling point of liquid nitrogen. Since then,
extensive research worldwide has uncovered many more oxide based
superconductors with potential manufacturability benefits and critical
temperatures as high as -1380C.
Hence, a superconducting material with a critical temperature above
-249.8oC is known as a High Temperature Superconductor (HTS), despite the continuing need for cryogenic
refrigeration for any application. High-temperature superconducting (HTS) cable,
characterized by high current density and low transmission loss, shows promise

15. as a compact large-capacity power cable that exhibits several environmental
advantages such as energy and resource conservations as well as no external
electromagnetic fields [1]. It must be noted that the “approximate zero resistance”
ascribed to HTS material applies to the transmission of direct current (DC)
power, while there is some electricity loss involved in AC transmission. HTS DC
cable takes maximum advantage of the characteristics of superconductivity [4].
Fig 1: Transition in Superconductor Discoveries [1]
However, there are absent of those problems unique to AC applications, HTS
DC cables are expected to outpace HTS AC cables, in line with future
performance enhancement and price reduction of converters. However, the
diagram above shows the transition in superconductor discoveries starting from
1911 through 2010 [1].
However, there are some challenges that are often encountered in the use of
superconductor in power system which include:

16.  Cost
 Refrigeration
 Reliability
 Acceptance
More so, many years of development and commercialization of applications
involving LTS materials have demonstrated that a superconductor approach
works best when; it represents a unique solution to the need. Alternatively, as the
cost of the superconductor will always be substantially higher than that of a
conventional conductor in the field of power system, it must bring overwhelming
cost effectiveness to the system. The advent of HTS has changed the dynamic of
refrigeration by permitting smaller and more efficient system cooling for some
applications [1].
Moreover, design, integration of superconducting and cryogenic technologies(at very low temperature)
demonstration of systems cost benefits and long term reliability must be met before superconductivity delivers on
its current promise of major societal benefits and makes substantial commercial inroads into new applications. It
is widely regarded as one of the great scientific discoveries of the 20th Century. This miraculous property causes
certain materials, at low temperatures, to lose all resistance to the flow of electricity. This state of approximately
zero loss enables a range of innovative technology applications. At the dawn of the 21st century,
superconductivity forms the basis for new commercial products that are transforming our economy and daily life.
However, Current Commercial applications of superconductors include the following [1]:
 Magnetic Resonance Imaging (MRI)
 Nuclear Magnetic Resonance (NMR)
 High-energy physics accelerators
 Plasma fusion reactors

17.  Industrial magnetic separation of kaolin clay
Hence the major commercial applications of superconductivity in the medical diagnostic, science and
industrial processing fields listed above all involve LTS materials and relatively high field magnets. Indeed,
without superconducting technology most of these applications would not be viable. Several smaller applications
utilizing LTS materials have also been commercialized, example, research magnets and Magneto-
Electroencephalography (MEG); the latter is based on Superconducting Quantum Interference Device (SQUID)
technology which detects and measures the weak magnetic fields generated by the brain. The only substantive
commercial products incorporating HTS materials are electronic filters used in wireless base stations. About
10,000 units have been installed in wireless networks worldwide to date [1].
2.1 SUPERCONDUCTOR MATERIAL
A Superconductor material differs fundamentally in quantum physics
behavior from conventional materials in the manner by which electrons or
electric current move through the material. It is these differences that give rise to
the special properties and performance benefits that differentiate superconductors
from all other known conductors [1]. A superconductor is an element or metallic
alloy which, when cooled to near absolute zero, dramatically lose all electrical
resistance. In principle, superconductors can allow electrical current to flow
without any energy loss (although, in practice, an ideal superconductor is very
hard to produce). In addition, superconductors exhibit the Meissner effect in
which they cancel all magnetic flux inside, becoming perfectly diamagnetic
(discovered in 1933). In this case, the magnetic field lines actually travel around
the cooled superconductor. It is this property of superconductors which is
frequently used in magnetic levitation experiments.
2.2 SPECIAL PROPERTIES OF SUPERCONDUCTOR MATERIALS

18. Approximately zero resistance and high current density have a major impact
on electric power transmission and also enable much smaller or more powerful
magnets for motors, generators, energy storage, medical equipment and industrial
separations. Low resistance at high frequencies and extremely low signal
dispersion are key aspects in microwave components, communications
technology and several military applications [1]. Low resistance at higher
frequencies also reduces substantially the challenges inherent to miniaturization
brought about by resistivity. The high sensitivity of superconductors to magnetic
field provides a unique sensing capability, in many cases 100 percent superior to
today’s best conventional measurement technology. Magnetic field exclusion is
important in multi-layer electronic component miniaturization, provides a
mechanism for magnetic levitation and enables magnetic field containment of
charged particles. The final two properties form the basis for digital electronics
and high speed computing well beyond the theoretical limits projected for
semiconductors. All of these materials properties have been extensively
demonstrated throughout the world. These properties of superconductor can be
summarized under the following points [1]:
 Zero resistance to direct current
 Extremely high current carrying density
 Extremely low resistance at high frequencies
 Extremely low signal dispersion

19.  High sensitivity to magnetic field
 Exclusion of externally applied magnetic field
 Rapid single flux quantum transfer
 Close to speed of light signal transmission.
2.3 HIGH TEMPERATURE SUPERCONDUCTOR
CABLE ARCHITECTURES
Interest in the field of superconducting power cable dates to the 1960’s, but
because conventional metallic superconductors required cooling with liquid
helium, these cable system designs were excessively complex and cost-
prohibitive. Interest in the field was renewed following the discovery of
ceramics-based high-temperature superconductors in the late 1980’s, which
enabled the use of liquid nitrogen as a cooling medium. Liquid nitrogen is widely
used in a variety of industrial applications and is recognized as a cheap, abundant
and environmentally harmless coolant [2].
Over the past several decades, a variety of cable designs were prototyped
and developed to take advantage of the efficiency and operational benefits of
superconductivity, while minimizing the additional capital and operating costs
that result from the requirement that HTS cables be refrigerated. Variations in
cable architecture have important implications in terms of efficiency, stray
electromagnetic field (EMF) generation, and reactive power (Volt Ampere
Reactive or VAR) characteristics. At present there are two principal types of HTS

20. cable. The simpler design is based on a single conductor, consisting of HTS wires
stranded around a flexible core in a channel filled with liquid nitrogen coolant
[2]. This cable design employs an outer dielectric insulation layer at room
temperature, and is commonly referred to as a "warm dielectric" design. It offers
high power density and uses the least amount of HTS wire for a given level of
Figure 1. Single-phase warm-
dielectric cable Figure 2. Single-
phase cold-dielectric cable
power transfer. Drawbacks of this design relative to other superconductor cable
designs include higher electrical losses (and therefore a requirement for cooling
stations at closer intervals), higher inductance, required phase separation to limit
the effects of eddy current heating and control the production of stray
electromagnetic fields (EMF) in the vicinity of the cable. Most of the HTS cable
demonstrations undertaken to date have been based on the warm dielectric
design.
An alternative design employs concentric layer(s) of HTS wire and a cold
electrical insulation system. Liquid nitrogen coolant flows over and between
both layers of wire, providing both cooling and dielectric insulation between the
center conductor layer and the outer shield layer. This is commonly referred to as
a coaxial, "cold dielectric" design. Cold dielectric HTS cable offers several
important advantages, including higher current carrying capacity; reduced AC
losses; low inductance; and the complete suppression of stray electromagnetic
fields (EMF) outside of the cable assembly. The reduction of AC losses enables
wider spacing of cooling stations and the auxiliary power equipment required to
assure their reliable operation [2].

21. 2.4 COMPARISM BETWEEN SUPERCONDUCTOR AND OTHER CONDUCTORS
Normal conductors have resistance which restricts the flow of electricity
and wastes some of the energy as heat. The resistance increases with the length of
the conductor. Superconductors have close to zero or zero resistance and a few
other properties, but the resistance is the most important one because it means
electricity can flow more efficiently through it. The drawback is that all the
superconductors we know of today have to be cooled down to extremely low
temperatures to achieve superconductivity [5].
CHAPTER THREE
3.0 METHODOLOGY
This chapter describes the procedures or steps adopted while carrying out the study. It is
discussed under the following points: area of study, instrument for data collection, method of data collection and
method of data analysis.
3.1 AREA OF STUDY
The area of study of this work has been chosen to be United States power
system grid. A superconductor application is still a young technology and has not been practiced in Nigeria.
3.2 INSTRUMENT FOR DATA COLLECTION
The researcher has chosen to consult the works of other scholars mainly.
This was taken due to lack of time and necessary materials for experimentation.
The option of structured questionnaire was avoided because the researcher could not

22. tour all round the area chosen due to logistic constraints. Also this instrument will be easy in terms of data
collection.
3.3 METHODS OF DATA COLLECTION
The researcher collected data for this study through visiting the internet
and works of scholars online, visiting the library to read books written by well know writers.
Data were also sourced using computer software like Encarta premium. The writer did not relent to have
discussion with colleagues in order to verify facts.
3.4 METHOD OF DATA ANALYSIS
The method the researcher used in analyzing data is data comparison. The
researcher gets information from different authors, compares them and uses the results to draw
out conclusion.
3.5 APPLICATIONS OF HIGH TEMPERATURE SUPERCONDUCTOR
IN POWER TRANSMISSION
Today’s power grid operators face complex challenges that threaten
their ability to provide reliable service; steady demand growth; aging
infrastructure; mounting obstacles to sitting new plants and lines; and new
uncertainties brought on by structural and regulatory reforms. Advances in high
temperature superconductivity (HTS) over the past two decades are yielding a
new set of technology tools to renew this critical infrastructure, and to enhance
the capacity, reliability and efficiency, of the nation’s power system. Power
industry experts in the United States have widely agreed that today’s aging power
grid must be strengthened and modernized. Utilities must cope with a growth in

23. the underlying level of demand driven by our expanding, high technology-
intensive economy [1].
Consumers in the digital age have rising expectations and requirements for
grid reliability and power quality. Competitive reforms have brought about new
patterns of power flows. EPRI (The Electric Power Research Institute) has
estimated that huge amount of resources must be spent over the next ten years to
achieve and maintain acceptable levels of electric reliability. At the same time,
utility shareholders are insisting on strong financial performance and more
intensive use of existing utility assets.
Moreover, gaining approval to site new infrastructure - both generating
plants as well as transmission lines - has become extremely difficult in the face of
landowner and community opposition and the NIMBY (“not in my back yard”)
phenomenon. This is especially the case in urbanized areas where power needs
are concentrated. As a result, utilities face lengthy and uncertain planning
horizons, as well as a rising risk of costly blackouts and other reliability
problems. The existing grid is also becoming increasingly regionalized with more
generation located remotely to be close to its particular source of fuel. The grid
will therefore have to mitigate increasing inter-regional fault current transfers and
the increasing number of parallel transmission paths that will be required to allow
lowest cost electricity to flow to where it is needed and to allow a smarter grid to
quickly respond to disruptions of sources, transmission or local generation paths
[1].

24. Distributed generation can help but is not always available when needed, and
also must be redesigned, possibly with the help of fault current limiters, to ride
through local fault and remain available. Solving this complex set of problems
will require a combination of new policies and technologies. Regulatory reforms
are needed to foster stronger incentives for grid investment and to overcome the
fragmentation that has impeded utilities ability to raise the required investment
capital.
Beyond all this new rules, however, the physical nature of the challenge
requires the adoption of advanced grid technologies, including those based on
HTS. These new HTS technologies have undergone rapid development in the
comparatively short time of two decades. The first HTS compounds were
synthesized in research laboratories in the late 1980s. Today, the HTS industry
has advanced to full-scale power equipment prototypes and demonstration
projects that are undergoing the rigors of in-grid evaluation. As these new
technologies are incorporated into the existing power system, they will offer
utilities new tools to ease the pressures that limit the performance and capacity of
their systems – with much lower space and land use impacts and with major
environmental benefits that are available using traditional grid upgrade solutions
[1].
3.5.1 HIGH TEMPERATURE SUPERCONDUCTOR WIRE
The foundation of these applications is a new generation of wire capable of
carrying vastly (on the order of 100 percent times) higher currents than

25. conventional copper wires of the same dimension, with approximately zero or
negligible resistive losses. Today’s prototype and demonstration technologies
have made use of a proven, readily available and high-performance first
generation HTS wire that is multi-filamentary in composition. Second generation
(2G) HTS wire, using coated conductor architecture and a variety of thin film
manufacturing processes, is rapidly making its way to market. 2G wire will
greatly broaden the addressable market for existing HTS devices because of its
predicted lower cost. It will also enable altogether new types of HTS applications
due to its superior performance characteristics in certain modes of operation. 2G
wire has been commercially available since 2006. HTS wire, in short, brings the
promise of a revolution in the way electricity is generated, delivered and
consumed - much as the introduction of optical fiber led to a technological leap
forward in the telecommunications industry. Among the power system
applications of HTS wire enables are the following:
3.5.2 HIGH TEMPERATURE SUPERCONDUCTOR POWER CABLES
Today’s conventional power lines and cables are being operated closer to their
thermal limits, and new lines are becoming hard to site. Compact, high-capacity
underground HTS cables offer an important new tool for boosting grid capacity.
Today’s advanced HTS cable designs enable controllable power flows and the
complete suppression of stray EMF.HTS power cables transmit 3-5 times more
power than conventional copper cables of equivalent cross section, enabling more
effective use of limited and costly rights-of-way. Significant progress toward the

26. commercialization of HTS cable is underway. Three major in-grid
demonstrations have been completed in the US including the world’s first HTS
power transmission cable system in a commercial power grid which is capable of
transmitting up to 574 megawatts (MW) of electricity, enough to power 300,000
homes. Two more demonstrations are in the planning stage in the US and another
dozen projects are active around the world [1].
3.5.3 HIGH TEMPERATURES TRANSFORMERS
Grid operators face a major challenge in moving power safely and efficiently,
from generators to consumers, through several stages of voltage transformation.
At each stage, valuable energy is lost in the form of waste heat. Moreover, while
demands are continually rising, space for transformers and substations -
especially in dense urban areas - is severely limited. Conventional oil-cooled
transformers also pose a fire and environmental hazard. Compact, efficient HTS
transformers, by contrast, are cooled by safe, abundant and environmentally
harmless liquid nitrogen. As an additional benefit, these actively-cooled devices
will offer the capability of operating in overload, to twice the nameplate rating,
without any loss of life to meet occasional utility peak load demands [1].
3.5.4 HIGH TEMPERATURE SUPERCONDUCTOR TRANSFORMERS
FOR WIND ENERGY
The increasing demand for clean, carbon free electric power, coupled with the
global warming crisis, has fueled tremendous interest in and development of

27. renewable energy technologies such as wind power. To break through the
economic barrier and ensure the future of this vast and critically important green
energy source, new technologies are needed offering lower weight, higher
efficiency, and significantly improved reliability. Direct drive wind generators
are utilizing a new high-efficiency stator design and replacing copper with HTS
wire on the rotor. Estimates are that a 10 MW drive utilizing HTS technology
would weigh about one third the weight of a conventional direct drive generator
with the same power rating. This reduction in weight would also allow an
increase in blade size and greater power output. The net effect is expected to
double the power system capacity of conventional systems and lower the cost of
wind generated energy [1].
3.5.5 ENERGY STORAGE
With power lines increasingly congested and prone to instability, strategic
injection of brief bursts of real power can play a crucial role in maintaining grid
reliability. Small-scale Superconducting Magnetic Energy Storage (SMES)
systems, based on low-temperature superconductor, have been in use for many
years. These have been applied to enhance the capacity and reliability of
stability-constrained utility grids, as well as by large industrial user sites with
sensitive, high-speed processes, to improve reliability and power quality. Larger
systems, and systems employing HTS, are a focus of development. Flywheels,
based on frictionless superconductor bearings, can transform electric energy into
kinetic energy, store the energy in a rotating flywheel, and use the rotational

28. kinetic energy to regenerate electricity as needed. Using bulk HTS self centering
bearings allows levitation and rotation in a vacuum, thereby reducing friction
losses. Conventional flywheels suffer energy losses of 3-5 percent per hour,
whereas HTS based flywheels operate at <0.1 percent loss per hour. Large and
small demonstration units are in operation and development [1].
3.5.6 HIGH TEMPERATURE SUPERCONDUCTOR FAULT CURRENT
LIMITERS
As new generators are added to the network, many local grids face a rising risk
of unacceptably high power surges that result from “faults” or short circuits.
These occasional surges are induced by adverse weather, falling tree limbs,
traffic accidents, animal interference and other random events. As fault current
levels rise, they pose a mounting risk that such surges will exceed the rating of
existing conventional circuit breakers, switchgear, bus, distribution transformers
and other equipment and expose grids to much more costly damage. HTS
technology enables a new solution: compact, “smart” fault current limiters
(FCLs) that operate passively and automatically, as power “safety valves” to
ensure system reliability when individual circuits are disrupted. Taking advantage
of the inherent properties of superconductors, they sense such dangerous over
currents and reduce them to safe levels by changing state instantaneously, from
“super” conductors to resistors. Several demonstrations of this breakthrough
technology are now underway, with an expected commercial horizon of 2010 [1].

29. 3.5.7 AN ENABLER OF THE ELECTRICITY REVOLUTION
The advent of HTS technology offers the opportunity for grid operators to move
to a new level of power system performance. Since the dawn of the utility
industry in the late 19th century, power system networks have been based almost
exclusively on components made of conventional materials such as copper,
aluminum and iron. The performance and capacity of the grid has been improved
and expanded over time. Yet grid performance is ultimately limited by the
inherent properties and limitations of these materials. HTS-based technology
removes many of these operational and space constraints. It offers grid operators
a new set of tools and strategies to improve the performance, reliability, safety,
land use and environmental characteristics of a power system. The need for such
new solutions is becoming acute with the relentless electrification of energy use -
a trend that makes our aging, heavily burdened grid more critical than ever to the
functioning of modern society. However, in many ways, the electric power
industry is at a crossroads. Within the past few years, electric power industry
structural reform efforts have stalled perceptibly. The current gridlock in policy
reforms and power flows is largely due to the mounting difficulty of expanding
the power delivery network. Without a way to expand the “superhighway
system” that supports power flows, recent competitive market reforms simply
cannot succeed. HTS technology can play an important role in “breaking the

30. gridlock” of power flows and policy reforms that threaten the power industry and
our overall economy.
However, before HTS technology solutions can enjoy broad acceptance,
they must undergo field trials. Such demonstrations play a crucial role in
establishing a record of reliability and working out grid integration issues.
Despite the acute needs facing the power system sectors, it is widely observed
that investor-owned utilities have taken a cautious and conservative approach to
adopting new technology solutions in recent years. This has resulted from several
factors including: a perception of asymmetric regulatory risks; disallowances
resulting from past technology failures; and the loss of sites where experimental
technologies can be tested without potentially adverse consequences for
customers. Industry restructuring efforts underway since the early 1990’s
moreover have had the unfortunate effect of undermining investment in jointly-
funded industry R&D [1].
3.6 BENEFITS OF HIGH TEMPERATURE SUPERCONDUCTORS IN
POWER TRANSMISSION
Using high temperature superconductor in power transmission can translate into
significant cost savings. The factors that lead to lower costs on an installed
system basis may be summarized as follows:
3.6.1 SHORTER LENGTHS

31. Short, strategic insertions of HTS cable could achieve the same power flow
benefit as lengthier circuits of overhead line. HTS cable need not be cost-
competitive with conventional cable or overhead line technology on a stand-alone
basis for it to offer a lower total cost solution. For example, with HTS cable
utilities may solve power flow problems with shorter circuit lengths, e.g.,
connecting to the more pervasive 11/33/66 Kv system rather than tying back to
the more distant EHV backbone transmission system [3].
3.6.2 LOWER VOLTAGES
Because of the higher capacity of HTS cable (approximately three to five times
higher than conventional circuits), utilities may employ lower-voltage equipment,
avoiding both the electrical (I²R) losses typical of high-current operation and the
capital costs of step-up and step-down transformers (as well as the no-load losses
within the transformers themselves). High-current HTS cables at 33 kV or even
11 kV may solve problems that would ordinarily require a 132 kV or 330 kV
conventional solution. The ability to operate at lower voltages translates into
lower costs for cable dielectric/insulating equipment, reduced hazards, as well as
lower cable and ancillary costs, which are driven by the voltage level of the
selected solution. In the long run, HTS may make unnecessary the much higher
system costs (e.g., transformer and breaker replacement) associated with wide-
area voltage up-ratings [3].
3.6.3 GREATER CONTROLLABILITY

32. HTS cable offers the ability to control power flows with conventional series
reactors, yielding market and reliability benefits typically associated with other
"controllable" forms of transmission e.g., FACTS (Flexible AC Transmission
Systems) or DC transmission. Yet this control at the terminal of a line would be
achieved with much less expense and complexity than is typically required using
conventional technologies (e.g., large, inflexible DC converter stations or the
large-scale power electronic devices often associated with conventional FACTS
devices). Whereas DC lines are limited to point-to-point flows, HTS cable
systems could be expanded to provide controllability to many points in a
network. This inherent controllability has important regulatory implications. For
example, HTS could form the basis for private, at-risk investment in merchant
transmission projects with assignable property rights in transmission capacity,
outside of the rate base framework, in situations where DC and conventional
FACTS solutions are not cost-competitive. The cost of DC systems is highly
impacted by the cost of converter stations. For short runs of DC transmission,
system costs are dominated by the cost of converter stations; HTS cables face no
such penalty [3].
3.6.4 LIFE EXTENSION AND IMPROVED ASSET UTILIZATION
HTS cable represents a new weapon to attack the principal enemy of congested
urban transmission systems: heat. Over time, thermal overload ages and degrades
cable insulation. By drawing flow away from overtaxed cables and lines,

33. strategic insertions of HTS cable can "take the heat off" urban power delivery
networks that are increasingly prone to overheating, the inevitable result of
increased loadings and acute siting difficulties associated with siting
conventional (copper or aluminum-based) system expansions. Reducing the
burden on existing electrical pathways will extend the life of conventional system
elements. This approach also improves overall asset utilization, and defers the
need for the large-scale capital investment required for the replacement of aging
and worn-out grid infrastructure [3].
3.6.5 EXPANDED GENERATOR SITING OPTIONS
Because it greatly reduces voltage drop, HTS cable has the ability to "shrink
electrical distance". This means that new generators could be located at greater
distance from urban loads (where land, labor and other costs are lower), while
providing the same degree of voltage support as if they were located in or
adjacent to the city center. Thus, HTS transmission lines could be deployed as
"virtual generators" to solve both power supply and reactive power problems [3].
3.6.6 REDUCED ELECTRICAL LOSSES
In specially optimized designs, cable can result in lower net energy losses than
occur in either conventional lines and cables or unshielded HTS cables with a
single conductor per phase, offering a transmission path with high electrical
efficiency. Because HTS circuits tend to attract power flow, they will naturally

34. operate at a high capacity factor, reducing the losses on other circuits and further
magnifying their efficiency advantage [3].
3.6.7 INDIRECT AND NON-MONETARY SAVINGS
In addition to these "hard cost" savings, HTS cable may result in other "soft
cost" savings. For example, time to install may be shortened because of reduced
siting obstacles associated with compact underground installations and less
burdensome siting requirements for lower-voltage facilities. HTS cables might be
routed through existing, retired underground gas, oil or water pipes, through
existing (active or inactive) electrical conduit, along highway or railway rights-
of-way, or through other existing corridors. While HTS cables “off-the-shelf” are
likely to cost more than conventional cables, the net cost of a fully installed cable
system may be lower because of the smaller space requirements associated with
HTS cables, and the ability to make adaptive reuse of existing infrastructure
where it exists, or the ability to use guided boring machines instead of costlier
and more disruptive trenching where such infrastructure does not exist. The
expansion of siting options would reduce the need for costly and controversial
expropriation proceedings. Indirect impacts on property values resulting from
overhead line construction would also be avoided. Communities that host HTS
projects would gain the benefit of higher property valuations, e.g., higher
property tax receipts and broader development options [3].
3.6.8 REDUCED REGIONAL CONGESTION COSTS

35. Finally, and perhaps most significantly, the ability to complete grid upgrade
projects more quickly will translate into the earlier elimination or relaxation of
grid bottlenecks. Solving physical bottleneck problems will sharply reduce the
grid congestion costs that, in today's unsettled, imperfectly competitive
marketplace, can impose huge penalties on consumers and the economy at large
[3].
3.7 ENVIRONMENTAL BENEFITS
Beyond the cost advantages outlined above, HTS cable will yield several
environmental advantages over conventional technology. Some of these
advantages are due to the very same characteristics of HTS cable that result in
lower-cost installed solutions. For example [3]:
 Underground placement: The underground placement of HTS cable will
eliminate the visual impact of overhead lines.
 Shorter cable lengths: Solving power flow problems with shorter lengths
of cable in more compact rights-of-way will reduce the disruptive effects
of construction.
 Reduced losses: The reduced losses in HTS circuits, as well as reduced
I²R losses on adjacent, conventional circuits that are offloaded due to the
"current hogging" effects of HTS cable, will translate into reduced fuel
consumption for generation.

36.  Environmentally harmless dielectric: Liquid nitrogen, the
coolant/dielectric of choice for HTS cables, is inexpensive, abundant and
environmentally compatible [3].
CHAPTER FOUR
4.0 DISCUSSIONS
The system study “Applications of High Temperature Superconductivity
(HTS) and its benefits in power system transmission”, lists the applications;
technical and economical benefits in power system generation, transmission and
distribution systems, and using components build up with HTS material
considering the state of the art in knowledge on superconductivity.
Besides minimal transmission losses, the ability to carry large current
densities is an important criterion for superconducting materials to create
favorable conditions for applications using this new technology. The current
densities of known HTS materials are about 100A/mmsq, which is at least 10
times larger compared to the current densities in conventional aluminum or
copper conductors.

37. Another interesting feature is the use of the transition from the
superconductor to the non superconducting state of the material. This property is
used for current limiting in power system. The advantages of the low energy
losses compared with the actual cost of investment and maintenance do not
justify an economical application of most superconducting components in power
system today. Therefore, additional benefits seem to be required in order to
guarantee a successful implementation of superconductor in the field of electric
power applications. An example of such benefit is the integration of the current
limiter and the superconducting transformer. This solution combines the two
element superconducting transformer with low energy losses and current limiter
in an advantageous manner. The current limiter permits then a decrease of the
transformer short circuit impedance, which one hand leads to a larger
transmission capacity and on the other hand allows for an improved voltage
stability at the secondary side of the transformer .These synergies lead to a
reduction of the investment cost, to more economical applications due to
integration as well as to an increase of energy efficiency in the transmission and
distribution system.
4.1 OUT COME OF CASE STUDIES
Detailed research activities are necessary to show the potential of using
high temperature superconductivity in the field of power system. Hence a set of
case studies have been investigated:

38.  Increase of transmission capacity by reducing impedances
 Increase of mesh of power system
 Increase of quality and availability of power system
 Re-dimensioning of elements used in power system
 Reduction of energy losses
 Reduction of environmental impacts
 Increase of the dynamic stability
 Integration of power production plants
 Development of new switchgear concepts
 Application of DC network in power system
The result of the system study is categorized as discussed below (ideas, solution
approaches and economical solutions).
I. IDEAS
The transmission capacity of a network can be increased due to the
realization of a network with low ohmic, coaxial or concentrically constructed,
superconducting cables and transformers. The high current capability of the HTS-
cable gives in selected cases the possibility to exchange the 380kv voltage level

39. by one of 110kv. Another possibility is to keep the 380kv level for the European
power system and to transform the power directly from 380kv to powerful
superconducting backbone-lines in the distribution network.
II. VISION
If government requirements change concerning environmental impacts for
the realization of overhead lines, it might be impossible to build new overhead
lines and it might be mandatory to replace existing overhead lines by
underground cables. HTS- cables could in such a situation, be the solution to
economically transmit the increasing need of energy in the major centers with a
low environmental impact. Possible scenarios are superconducting connections
through road or railway tunnels in mountain areas with the aim to reduce the
number of the overhead lines and to decrease transmission losses as well as a
backbone solution for the transit of energy.
III. ECONOMICAL SOLUTIONS
The result of case studies concerning the integration of current limiters in
power system show the great potential using these elements in a technically
efficient manner independent of the nominal power in all voltage levels of power
system. The actual production costs are difficult to calculate in detail. It must be
assumed that the cost lie in a range affordable. An investment cost at the upper
end of this range allows an economical use, especially in regional distribution

40. and industrial power system. An important advantage resulting from the
introduction of current limiters in distribution system is the use of load breakers
instead of the expensive short circuit breakers as switching devices.
The main benefits of the superconducting transformers are the low energy
losses, the decrease in weight and volume as well as the reduction of
environmental impacts. Due to it’s the behaviors of the superconducting
transformers at restart, its first economical applications are seen in urban cable
networks and as blocks transformers in power plants. The integration of the
current limiting function in transformers will increase number of economically
advantageous applications.
IV. SOLUTION APPROACHES
The replacement of conventional copper cables by HTS-cables in existing
ducts result in the simultaneous effect that in the same space more power with
less electrical losses can be transmitted. Due to the larger current densities
compared to conventional cables, superconducting cables must be constructed in
a new manner.
Besides the coaxial construction principle, a concentric construction
principle might also be possible. With these two construction variations, the
electromagnetic influence outside of the cable can be eliminated. This will be a
requirement considering the expected applications of large current density. With

41. the mentioned constructions principles, it would for instance be possible to
manufacture 110kv HTS-cables with similar physical parameters and
transmission capacity as 380kv conventional overhead lines. The use of
superconducting cables is most promising for direct current networks. Large
current applications imply the possibility to eliminate some voltage levels of an
electrical network.
Due to this effect, the DC superconducting cables may cost about 4 times
as much as the conventional cables. Moreover, the following conclusions are
important from a technical point of view:
Superconducting cables with nominal voltages higher than 20kv can be realized
in a technical efficient manner both for AC and DC system;
The use of HTS-DC cables is economically more attractive than the application
of HTS-AC-cables. The essential advantages are the effect of no losses in the
duct and no dielectric losses as well as the very compact design.
The application of the high temperature superconducting magnetic energy
storage devices (SMES) is not economical compared with the flywheel. Reasons
are the physical parameters of existing BISSCO HTS-materials. These materials
have a large decrease of the critical current density in a relatively small magnetic
field. If in future the HTS-material YBCO will be available, the comparison has

42. to be repeated because the stability of the magnetic field of this material is much
better.
4.2 ANALYSIS OF THE RESARCH
4.2.1 ANALYISI ON TRANSFORMER APPLICATION
The basic design process for the HTS transformers is similar to that of
conventional transformers. A good design is a function of the optimal use of
active materials such an iron-core, HTS material and cryogenic cooling system.
Below are a few analyses that are significant impact on the size, weight, cost and
performance of HTS transformer.
a) AC losses in HTS winding: CTC is used in the design analysis in order to
minimize the AC losses in the winding. The AC losses could represent a
significant portion of the total thermal load on the refrigeration system, but no
reliable analysis is available for estimating these losses while a CTC carries the
AC and experiences the external AC field.IRL and others are in process of
developing AC loss analysis formulations. Due to unavailability of good analysis
basis, AC losses have not been estimated for the windings.
b) Size and weight: Voltage per turn is a measure of core limbs cross section.
A larger core cross section may lower HTS consumption at the expense of larger
weight and size. The larger core will also require bigger diameter coils. However,
a manufacturer may prefer winding diameter no larger than what their existing

43. machinery can handle. Thus, by keeping the core diameter similar to that of
conventional transformers, it is possible to reduce the overall size and weight of
HTS transformers of similar rating. In other words a transformer manufacture
could produce HTS transformers of twice the rating within the capabilities of
their existing winding and handling equipment and facility space. However, some
customers may not mind the larger weight caused by the larger diameter core,
provided that the product price is lower .selection between the two approaches is
better made by discussion between a customer and a manufacturer.
c) Operating temperature: A conventional oil-cooled transformer designed
for 100 degrees Celsius operation can be operated at 50 percent overload by
circulating oil in the tank and at 100 percent overload by providing additional
cooling fans. Similar ratings are also possible with HTS transformers. For
example if an HTS transformer is designed for operation at 77k ,then it is
possible to overload it by 50 percent and 100 percent by operating it at 70k and
64k, respectively. Lower temperature operation will require additional cryogenic
cooling capacity.
d) Operational constraints: Since HTS winding are more compact than
copper winding of a conventional transformer, the leakage reactance of HTS
transformers can be designed to be low. A low leakage reactance result in lower
output voltage variations between no –load and rated load conditions. It might
also be possible to eliminate use of tap changers typically employed to correct

44. output voltage as a function of load. However, lower leakage reactance generates
higher through fault current and forces during a short circuit event experienced
by a transformer. Thus a compromise is needed between lower leakage reactance
and acceptable fault current.
4.2.2 ANALYSIS ON FAULT CURRENT LIMITERS APPLICATION
High temperature superconductor technology permits a modern solution to
eliminate surge in power system transmission. This is as a result of its compact
and simplicity in any system incorporated. It allows the passive and automatically
operated circuit as power safety valves. Also because of its transition from
superconductor to resistor when a high current density passed through the
material, this particular application was able to achieve.
4.2.3 ANALYSIS ON HTS POWER CABLE AND WIRE APPLICATION
The basis of these particular applications is a new technology of wire
capable of carrying more than 100 percent higher currents than conventional
cables/wire of the same dimension, with approximately zero or negligible
resistive losses. Looking at Nigeria power grid, characterized by aluminum or
copper cable/wire it has being marked with low voltage as a result of its radial
network. In which if this HTS cable is used in the network will account for less
loss in the network and deliver equal voltage in the sending end of the power
system
4.2.4 ANALYSIS ON ENERGY STORAGE APPLICATION

45. Power system is often marked by instability of supply. Superconducting
Magnetic Energy Storage system can solve this issue based on low temperature
superconductor. These can been apply to enhance the capacity and reliability of
stability-constrained utility grids; For example Flywheels, based on frictionless
superconductor bearings, can transform electric energy into kinetic energy, store
the energy in a rotating flywheel, and use the rotational kinetic energy to
regenerate electricity as needed. And this will ensure continuity in the system.
Generally, the integration of high temperature superconductor in power
system transmission is as a result of its following features which in include:
environmentally harmless dielectric, reduced loss, shorter cable lengths, highly
efficient in underground placement, indirect and non-monetary savings, reduced
regional congestion costs, expanded generator siting options, life extension and
improved asset utilization, greater controllability, lower voltages as the author
has highlighted above.
4.3 COST OF RESEARCH
This research work is relatively expensive to the author. This is so because
the researcher lacks the necessary material to carry out the work effectively.
Hence, he relents on online material by browsing through a subscription made to
GLO/MTN network using modem, thus this subscription make the work
expensive.

46. 4.4 PROBLEMS ENCOUNTERED IN THE CAUSE OF WRITING
THIS RESEARCH WORK
As a result of carrying out this research work the author encountered many
problems which include:
a. The use of high temperature superconductor is not used in Nigeria where the
author is leaving, thus he could not get some information required to carry out the
research work effectively.
b. The usual problems of power failure also pose a great obstacle during the
research work.
c. The author also encountered the problem of analyzing the online material and
other material collected in the cause of writing this work and putting it in a
simple language that can be generally understand by anybody.
d. Also the author lacks some statistical material and equipment to carry out the
experimental study.

47. CHAPTER FIVE
CONCLUSIONS AND RECOMMEDATION
5.0 CONCLUSION
Given today's acute level of concern about power system reliability and
new competitive pressures, it brings to our notice that strategies to control and
redirect transmission flows have greater value than ever before. As power
transmission problems have intensified across the nation's grid over the past few
years, the need for new technology solutions has become apparent. HTS cables
constitute new tools to develop these strategies. By taking advantage of their
outstanding features, utilities and regional transmission operators will find new
and less expensive ways to tackle grid congestion problems, reduce grid security
violations, improve overall asset utilization and extend the life of their existing
systems.

48. Also, the widespread commercial adoption of these superconducting devices for
power networks has great potential to generate a range of economic,
environmental and reliability benefits, many of which are discussed herein.
Yet, as is often the case with many “breakthrough” technologies that are initially
high-cost, early developers, and users face high risks. These risks are
compounded by the very uncertainties and regulatory complications that VLI
cable could ultimately help to resolve. It is important, therefore, to undertake all
appropriate steps to speed the commercialization of this promising technology.
5.1 RECOMMENDATION
Generally series of demonstration projects to illustrate the power flow attributes
of HTS cables, to develop a reliability record for the technology, and to resolve
system integration and other issues should be a top priority of public officials
responsible for power system related policy.
As in the case where the author is residing the new technology is not in practice
at all. Thus he urges utilities, experts and the federal government to embark on
the use of the new technology as integration in power system components so as to
reduce the problems of power system in the country in which it can address as
seen from this study. Which include in high temperature superconductor wire,
high temperature superconductor power cables, energy storage, high temperatures
transformers and high temperature superconductor fault current limiters etc.

50. REFERENCE
[1] IEEE CSC council on superconductivity, Superconductivity its present and
future application.
[2] John Howe, Very low impedance superconductor cables, concepts,
operational implications and financial benefits.
[3] Pascale Strubel, A cost-effective way to upgrade urban power networks while
protecting the environment.
[4] High-Temperature Superconducting Wind Turbine Generators Wenping Cao
Newcastle University upon Tyne United Kingdom
[5] Wikipedia- what is the difference between superconductor and other
convectional conductor.
[6] B. R. Oswald, Technical and Economical Benefits of Superconducting Fault
Current Limiters in Power Systems
[7] Dr.G Schnyder, Application of high temperature superconductor in power
system