Wednesday, November 5, 2014
Sharing APIC Collaborative Research Results and Experiences
Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
October 15, 2014
Dear Delegates;
The Alberta Power Industry Consortium (APIC) is pleased to welcome you to our 7th Annual Alberta
Power and Energy Innovation Forum, “Sharing APIC Collaborative Research Results and Experiences”.
This year’s forum showcases a number of projects conducted by the University of Alberta in close
collaboration with APIC companies. These projects provide scientific support to the decision making
of APIC companies or introduce technical innovations to help their engineering work. The presenters
also share their collaborative experiences with you so that your department can take advantage of
the opportunities offered by the APIC platform.
We are very pleased to have Mr. Mark F. McGranaghan, Vice-President of Electric Power Research
Institute,( EPRI) US, as a guest speaker to the Forum. Mark will share his thoughts on emerging
technologies and innovations in the utility industry.
I would like to thank the presenters who have generously agreed to share their experience. Also, in
the spirit of collaboration a number of students, ElTs and researchers are also displaying posters of
their research results or project findings. We appreciate your time and contribution to the forum.
Our forum would not be possible without the support of the organizing committee and numerous
volunteers. Many thanks for their good work.
I hope you will enjoy our forum, and look forward to meeting you.
Barrie Gorrie
Chair, Board of Alberta Power Industry Consortium
Director, Distribution Engineering, ATCO Electric
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Table of Contents
About APIC ................................................................................................................................. 1
General Information .................................................................................................................... 2
Forum Location .............................................................................................................................. 2
WiFi Connection ............................................................................................................................ 2
Forum Website .............................................................................................................................. 2
Downloading Forum Materials Online .......................................................................................... 2
Forum Program ........................................................................................................................... 3
Presentations and Speaker Biographies ....................................................................................... 4
Poster Presentations – Industry Engineers in Training ................................................................ 14
Poster Presentations – University of Alberta Researchers ........................................................... 15
Summaries of APIC Project Reports ........................................................................................... 17
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
About APIC
The Alberta Power Industry Consortium (APIC) consists of six Alberta utility companies,
AESO, AltaLink, ATCO Electric, ENMAX, EPCOR and FortisAlberta, and the University of
Alberta. Established in the fall of 2007, its goal is to bring Alberta power companies
together, with the University of Alberta as the coordinating organization, to solve technical
problems of common interest, to produce more power engineering graduates, to support
the professional development of APIC employees, and to promote technical cooperation
and exchange in Alberta’s power utility companies.
APIC operates under the guidance of an Industry Advisory Board. Current board members
are:
Dan Shield, Director, Transmission Engineering & Performance, AESO
Daniel Wong, Principal Engineer, ALTALINK, L.P. Management Ltd.
Barrie Gorrie, Senior Manager, Distribution Engineering, ATCO Electric Ltd.
Ken Chao, Director, Projects & Engineering, ENMAX Power Corporation.
Suresh Sharma, Director of Transmission, EPCOR Distribution & Transmission Inc.
Richard Bahry, Senior Manager of Distribution Planning, FortisAlberta Inc.
Wilsun Xu, Research Chair Professor, University of Alberta
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
General Information
Forum Location
The forum is held in the Solarium, on the 2nd floor of the Engineering Teaching and Learning
Complex (ETLC building) of the University of Alberta, at 9107 - 116 street, Edmonton.
A map of the University of Alberta campus is here: http://www.campusmap.ualberta.ca/
WiFi Connection
A WiFi connection is available courtesy of the University of Alberta.
The connection id is: Guest@UofA. No password is required.
Forum Website
The website of the forum can be accessed at: http://www.ece.ualberta.ca/~apic/
(click on ‘Innovation Forum’ on the left side of the page)
or at: http://www.ece.ualberta.ca/~apic/pmwiki.php?n=Forum.Homepage2014
Downloading Forum Materials Online
Presentations and other forum materials can be downloaded via the forum website.
The password for accessing the materials is: APIC2014UofA
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Forum Program
Time Activity and Speaker
Morning
8:00 – 8:30 Breakfast, registration and poster session
8:30 – 8:40 Welcome and Opening Remarks Wilsun Xu, Professor, University of Alberta
8:40 – 9:10 APIC Activities and Benefits to Industry Partners Barrie Gorrie, Chair, APIC Board and Director, Distribution Engineering, ATCO
9:10 – 9:40 Magnetic Field Emission From Electronic Meters, FortisAlberta Zurex Fontanilla, Senior Engineer, Power Quality Robert Heimann, Manager, Meter Data Management & Technical Services
9:40 – 10:10 Effectiveness of Equipotential Bonding Mats for Hydro-excavation, EPCOR Ray Cislo, Compliance Specialist, Health, Safety & Environment Richard Vercholuk, Trainer, Hydro-Vac U3
10:10 – 10:40 Coffee break and poster session
10:40 – 11:10 Implementation Strategy for Harmonic Monitors in the Calgary Transmission System, ENMAX Samantha Hoffman, Transmission Planning Engineer
11:10 – 11:40 Feeder Neutral Potential Rise Due to GPR Transfer and Induction, ATCO Electric Alexandre Nassif, Senior Engineer, Power Quality & Technical Services
11:40 – 1:00 Lunch and Poster Session U of A researchers will present research work in posters and demonstrations.
Afternoon
1:00 – 1:45 Invited Talk: Emerging Technologies and Innovations for Utility Industry, Electric Power Research Institute (EPRI), United States Mark McGranaghan, Vice-President of EPRI
1:45 – 2:15 Estimation of Fault Resistance from Fault Recording Data, Altalink Daniel Wong, Principal Engineer, Protection & Control Michael Tong, Team Lead, Disturbance Analysis & System Operations
2:15 – 2:45 Coffee break and poster session
2:45 – 3:15 Transmission Line Impedance Estimation Using SCADA Data, AESO James Shen, Principal Engineer, System Operations
3:15 – 3:45 New Methods to Mitigate Power System Harmonics, University of Alberta Wilsun Xu, Professor, University of Alberta
3:45 – 4:00 Closing Remarks and Acknowledgements Barrie Gorrie, Chair, APIC Board and Director, Distribution Engineering, ATCO
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Presentations and Speaker Biographies
1. APIC Activities and Benefits to Industry Partners Barrie Gorrie, Chair, APIC Board and Director, Distribution Engineering, ATCO
Barrie graduated from University of Alberta in 1980. Upon graduation, he went to work with
ATCO Electric where he has held various engineering, operations, and management positions.
Barrie is currently the Director Engineering and Chief Engineer of ATCO Electric - Distribution
Division.
2. Magnetic Field Emission From Electronic Meters, FortisAlberta Zurex Fontanilla, Senior Engineer, Power Quality
Robert Heimann, Manager, Meter Data Management & Technical Services
Zurex Fontanilla is a graduate of Electrical Engineering from the University of Santo Tomas in
the Philippines. Zurex worked for Manila Electric Company (MERALCO) upon graduation and
has over 23 years of technical engineering experience. His work experience includes design
and operation of distribution assets. He currently holds a position with FortisAlberta as Sr.
Engineer, Power Quality. Zurex is a member of CSA Technical Committee C577
Electromagnetic Compatibility, FortisAlberta representative on the Canadian Electricity
Association Power Quality Task Group and a registered professional engineer in the province
of Alberta.
Robert Heimann is a 1985 graduate of Electronics Engineering Technology from the Southern
Alberta Institute of Technology, has a Management Development Certificate from the
University of Alberta and holds a Professional Manager designation from the Canadian
Institute of Management. Robert has 29 years of utility experience related to revenue
metering, implementation of FortisAlberta’s automated metering infrastructure, distribution
equipment refurbishment and ISO quality programs. His metering expertise and leadership
has benefited the metering industry in his role as Chair and participant of various
Measurement Canada working groups related to Federal Metering Policy, as well as the
FortisAlberta management representative on the Canadian Electricity Association Metering
Task Group.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Notes
Speaker presentations can be accessed online at: http://www.ece.ualberta.ca/~apic/
Click on ‘Innovation Forum’ on the left-hand side of the web-page.
Under ‘Download Forum Materials’, the password is: APIC2014UofA
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Presentations and Speaker Biographies
3. Effectiveness of Equipotential Bonding Mats for Hydro-excavation, EPCOR Ray Cislo, Compliance Specialist, Health, Safety & Environment
Richard Vercholuk, Trainer, Hydro-Vac U3
Ray Cislo holds degrees in electrical engineering from the University of Toronto and Human
Kinetics from the University of Guelph. Combining technical and human performance
knowledge, Ray has prepared medical and hospital safety standards with CSA, worked as a
clinical engineer with the Royal Alexandra Hospital, and prepared Alberta’s Occupational
Health and Safety Code as a Government of Alberta OHS regulator. For the past 4 years he has
done occupational health and safety work with EPCOR. His present responsibilities as a work
methods advisor means he helps crews develop new practices and refine existing ones.
Helping to critically review the use of portable bonding mats is an example of that work.
Richard Vercholuk is a proud 15-year EPCOR employee with a strong commitment to his work.
For the past ten years, Richard has worked as a both a Hydro-vac operator and a
supervisor/trainer. Richard’s primary responsibilities at EPCOR Technologies support the safe
and efficient operation of a fleet of hydro excavators. His day-to-day responsibilities include
training and supervising hydro-vac operators and swampers, orientating hydro-vac
contractors, supervising worksites, and planning and organizing projects involving hydro-
excavation. Researching safer and more efficient work methods and solutions for every-day
jobs to complex projects is Richard’s passion. He aims to provide his colleagues with the
knowledge and confidence they need to hone their skills as operators and accomplish their
work in a safe and productive manner.
4. Implementation Strategy for Harmonic Monitors in the Calgary
Transmission System, ENMAX Samantha Hoffman, Transmission Planning Engineer
Samantha Hoffman is a 2010 graduate of the Electrical Engineering Honours program at
McGill University. Samantha spent a year as an intern working at ABB’s Corporate Research
Centre in Switzerland and worked for ENMAX Corporation upon graduation. She has over 5
years of technical engineering experience. Her work experience includes programming tools
for a substation simulator, the project management and design of distribution and
transmission substation upgrades, performing power system studies on the Calgary
transmission system and developing transmission projects for execution. She has a special
interest in the development of project staging and constructability assessments of large-scale,
brownfield transmission projects. Samantha currently holds a position with ENMAX Power
Corporation as a Transmission Planning Engineer. She is a registered professional engineer in
the province of Alberta. In her free-time, Samantha can be found hiking, biking and
backpacking in the Rocky Mountains.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Notes
Speaker presentations can be accessed online at: http://www.ece.ualberta.ca/~apic/
Click on ‘Innovation Forum’ on the left-hand side of the web-page.
Under ‘Download Forum Materials’, the password is: APIC2014UofA
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Presentations and Speaker Biographies
5. Feeder Neutral Potential Rise Due to GPR Transfer and Induction, ATCO
Electric Alexandre Nassif, Senior Engineer, Power Quality & Technical Services
Alexandre Nassif received his Ph.D. degree from the University of Alberta in 2009, a degree
obtained under the supervision of Dr. Xu. From 2009 to 2012 he worked as a Transmission
Protection Planner in Hydro One, Toronto, and in 2012 he joined ATCO Electric Distribution as
a Senior Engineer, Power Quality. Alex is a licensed Professional Engineer in the province of
Alberta and a Senior Member of IEEE.
6. Emerging Technologies and Innovations for Utility Industry, Electric Power
Research Institute (EPRI), United States Mark McGranaghan, Vice-President of EPRI
Mark McGranaghan is Vice President of Power Delivery and Utilization for the Electric Power
Research Institute (EPRI). He leads the teams responsible for EPRI's research involving
technologies, systems, and practices for power delivery systems from the generator to the
plug and for the devices and technologies that use the electricity.
From 2003 to 2010, McGranaghan was Director of Research in the Distribution and Smart Grid
areas for EPRI. Priorities during this period were restructuring of the distribution research
program, coordinating EPRI research in the smart grid area with government and industry
efforts, creating the smart grid demonstration initiative, and increasing the technical strength
of the EPRI research team.
Prior to joining EPRI, McGranaghan was Vice President at Electrotek Concepts (1998-2003),
where he helped develop a new business area around power quality and power system
studies into a world leader.
From 1978 to 1988 McGranaghan was a Manager at McGraw-Edison/Cooper Power in
Canonsburg, Pennsylvania. He managed studies for the utility industry and internal studies for
application of McGraw-Edison products (power transformers, circuit breakers, arresters,
distribution switchgear, capacitors) and directed a wide range of power system studies.
McGranaghan has Bachelor of Science, Electrical Engineering and Master of Science, Electrical
Engineering degrees from the University of Pittsburgh. He has taught seminars and workshops
around the world and is very active in standards development and industry activities (IEEE,
CIGRE, IEC). He is a member of the NIST Smart Grid Interoperability Panel Governing Board
and he is the Vice-Chairman of the CIRED U.S. National Committee.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Notes
Speaker presentations can be accessed online at: http://www.ece.ualberta.ca/~apic/
Click on ‘Innovation Forum’ on the left-hand side of the web-page.
Under ‘Download Forum Materials’, the password is: APIC2014UofA
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Presentations and Speaker Biographies
7. Estimation of Fault Resistance from Fault Recording Data, Altalink Daniel Wong, Principal Engineer, Protection & Control
Michael Tong, Team Lead, Disturbance Analysis & System Operations
Daniel Wong received his B.Sc. degree from University of New Brunswick in 1975, and worked
as a Lab Instructor in UNB. From 1976 to 1981, Daniel worked for NB Power in the Distribution
Department. From 1981 to 2000, Daniel worked for TransAlta Utilities. He had held many
key roles in Power System Protection. From 2000 to 2005, Daniel worked for General Electric.
His major accountabilities were: Lead Protection Engineer, Product Line Manager and Asia
Sales Liaison. In June 2005, Daniel joined AltaLink in as the Principal Engineer for Protection &
Control. Daniel has over 39 years of engineering experience in Electric Power Industry. He is a
Professional Engineer in Alberta and New Brunswick, and an IEEE Senior Member. He is also
an Executive Board Member of APIC.
Michael Tong received his B.Sc. degree in Electrical Engineering in 1991, from Shanghai Jiao
Tong University, Shanghai, China. He is currently the Team Lead of the Disturbance Analysis
Group in AltaLink, an electric transmission company serving Alberta, Canada. Michael has
been working in the domain of electric power system for over 20 years, and he is a
Professional Engineer in Alberta.
8. Transmission Line Impedance Estimation Using SCADA Data, AESO James Shen, Principal Engineer, System Operations
James Shen received his M. Sc. degree in Power System Engineering from Shanghai Jiaotong
University, China in 1982, and M. Sc. degree in Electrical Engineering from University of
Saskatchewan in 1988. In 1998 he joined Power Pool of Alberta/AESO and worked at different
departments and now is a principal engineer in Power System Applications of Operations
Systems. His specialties include power system analysis, and design/development of business
solutions and market applications and systems. He worked as an engineer at Enmax for many
years and before moved to Canada he was a university faculty in Shanghai Jiaotong University,
China. He is a registered professional engineer in Alberta and a member of IEEE.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Notes
Speaker presentations can be accessed online at: http://www.ece.ualberta.ca/~apic/
Click on ‘Innovation Forum’ on the left-hand side of the web-page.
Under ‘Download Forum Materials’, the password is: APIC2014UofA
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Presentations and Speaker Biographies
9. New Methods to Mitigate Power System Harmonics, University of Alberta Wilsun Xu, Professor, Department of Electrical and Computer Engineering
Dr. Wilsun Xu received a B.Sc. degree from China in 1982 and a Ph.D. degree from the
University of British Columbia, Vancouver, Canada, in 1989. From 1989 to 1996, he was with
BC Hydro as an Electrical Engineer. He has been with the University of Alberta, Edmonton,
Canada, as a Faculty Member since 1996 and is currently a NSERC/iCORE Research Chair
Professor. His current research interests are power disturbance issues such as power quality
and power disturbance analytics.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Notes
Speaker presentations can be accessed online at: http://www.ece.ualberta.ca/~apic/
Click on ‘Innovation Forum’ on the left-hand side of the web-page.
Under ‘Download Forum Materials’, the password is: APIC2014UofA
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Poster Presentations – Industry Engineers in Training
1. EIT Experience of Altalink Sameh Al-Eryani, EIT, AltaLink
Sameh Al-Eryani joined AltaLink in 2011 as a substation equipment engineer EIT in the
Engineering Standards and Support group. In his current role, he develops engineering
standards and equipment specifications and support principal engineers with long term
sparing strategies and new technology evaluations. Sameh obtained his BSc. Degree in
electrical engineering from the University of Calgary in 2011 and is currently pursuing his MSc.
at the University of Calgary on part time basis.
2. EIT Experience of Altalink Chu Cheng, Anas Alhomsi, EIT, AltaLink
Chu Cheng joined AltaLink in 2012 for a 16 month internship. Since she has graduated from
Electrical Engineering at the University of Calgary and has jumped into expanding her
protection and control knowledge and is becoming a valuable asset to the Operational
Engineering team.
Anas Alhomsi joined AltaLink in 2012 for a 16 month internship after completing his third year
of Electrical Engineering with a specialization in Energy and Environment at the University of
Calgary. Since graduation he is working in System Operations and adds value to his team by
preparing outages risk assessments and dealing with real time issues on the system.
3. Overview of Solar Industry in Alberta Michael Chai, EIT, ENMAX
Michael Chai is a 2014 graduate of Energy Systems Engineering from University of Toronto.
Michael worked for Toronto Hydro as an Intern before joining ENMAX Corporation upon
graduation in 2014. His work experience includes Risk-Based Asset Management, Network
Design and Distributed Generation. He has a special interest in the Optimization and Power
Electronics of Renewable Energy Systems. Michael currently holds an EIT position with
ENMAX. Michael is an active member of the IEEE and was the 2013-2014 Chair the IEEE UofT
Student Branch.
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Poster Presentations – University of Alberta Researchers Presenter Title
Alaei, Ramiar A Review on High Power Multilevel Converters
Ding, Tianyu (Tyrone) Micro-filter scheme to mitigate harmonics in residential systems – feasibility research*
Ding, Tianyu (Tyrone) Harmonics in the Alberta power transmission system*
Gao, Pengfei Investigation on EMF emission from electronic meters*
Gao, Pengfei Sensor for telephone interference measurement
Haji Moghimi, Moosa A Survey on Power System Steady-state and Dynamic Equivalents
Li, Benzhe Electrical Signatures of Utility Equipment Failure
Li, Xiang Micro-filter scheme to mitigate harmonics in residential systems – hardware research
Li, Xin (Shawn) Characteristics of Interharmonics Produced by VFDs
Liu, Zhixue (Sam) A Novel circuit-breaker failure protection scheme
Shabestary, Masoud A Comparative Study on Low-Voltage Ride-Through Reference-Current-Generation (LVRT-RCG) Strategies in Converter-Interfaced DG Units
Shabestary, Masoud Maximum Allowable Reactive Power Delivery under Different Grid Faults and Respecting Phase-Currents-Limitation Imposed by DG Owners
Shaloudegi, Kiarash Spectral Learning: Application for Non-Intrusive Home Appliance Monitoring
Wang, Yang (Frank) Fault Resistance Estimation Based on Fault Records*
Wang, Yang (Frank) Transmission Line Impedance Estimation Using SCADA Data*
Wu, Wenriu Real-time Large-scale Matrix Solver in Power Flow Problem Using FPGAs
Xia, Bing (Michael) Feeder Neutral Potential Rise due to GPR Transfer & Induction*
Xia, Bing (Michael) Effectiveness of Equipotential Bonding Mats for Hydro-excavation*
Zhang, Wenhai Circuit Parameters Calculation Based on Damped Sinusoidal Signal & Its Applications
Zhou, Yaxiang (Peter) Novel Resynchronization Strategies for Microgrid
Sun, Yuanyuan (Summer)
Modeling of voltage source inverter based VFD for harmonic analysis
Zhu, Ke Capacitor condition monitoring using coded-energization scheme
Zhu, Ke Method to monitor conditions of substation capacitors
Galvan, Juan Temperature Reduction of Power Transformer Tanks due to Stray Losses
Yong, Jing Inductive coordination between distribution feeders and pipelines
Liang, Hao Plug-in Electric Vehicle Charging Demand Estimation via Queueing Network Analysis
*Posters & demos related to presentations
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Summaries of APIC Project
Reports
University of Alberta
For a copy of those reports, e-mail Dr. Wilsun Xu at: [email protected]
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Report No. 2014B-1
Modeling of Variable Frequency Drives for
Power System Dynamic Studies
August 2014
Variable Frequency Drives (VFDs) are widely used in various industrial applications and make an
increasingly large portion of total loads in industrial facilities. However, dynamic models of VFDs are
currently not available for power systems dynamic studies.
This report presents two sets of research results on the subject of developing models of VFDs for
power systems dynamic studies. The first set of research results clarifies how a VFD responds to
voltage sags. Voltage sags occur when power systems experience short-circuit faults, which is
typically the starting point of power systems dynamic simulation. This research shows that VFDs will
trip when they experience a relatively large voltage sag (>20% - 30% voltage drop). As a result, there
is no need to include VFDs in dynamic studies in this case. Based on the finding, a simple procedure
to determine if a VFD needs to be included for dynamic studies is proposed and presented in this
report.
The second set of research results presents how to model VFDs when they experience mild voltage
disturbances and are able to ride through. The equivalent dynamic models for motor drive systems
dedicated under such conditions are proposed. These models are created using the linearization
approach and include effects of the drive, the motor, and the control system. Aggregation algorithms
for motor drive systems are also proposed to achieve load equivalence facility wide.
Due to significant different topologies for different types of drives, the mathematical models of the
motor drive systems are different. The equivalent dynamic models are created for the two common
motor drive systems, low voltage VSI drives and medium voltage cascaded inverter drives, with their
induction motor loads in this report. These models are expressed by 7th order transfer functions. Both
voltage dependency and frequency dependency are considered in the models. The equivalent
dynamic models and aggregation algorithms are verified to be accurate by comparing dynamic
responses of the developed models with that of the detailed switching models by case studies. The
dynamic model derivation for other types of motor drive systems can serve as the future work.
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Report No. 2014A-1
Feeder Neutral Potential Rise Due to GPR
Transfer & Induction
June 2014
The neutral potential rise (NPR) of MGN feeders is a safety concern because the
neutral grounding points could be located in public areas. The step voltage around
the neutral grounding point may exceed the safety voltage limitation. There are two
causes for NPR and both are associated with fault situations. The first cause is the
transfer of substation ground potential to the neutral if the feeder neutral is
connected to the substation neutral. The second cause is the induction of voltages
on feed neutral by the fault current. This situation arises when the feeder is not
connected to the substation neutral.
This project has determined the key factors affecting the NPR for both causes and
proposed practical methods to estimate the NPR levels. An intuitive explanation on
the mechanism of NPR is also established. One of the potential applications of the
findings is to determine if a feeder neutral should be connected to the substation
neutral from safety perspective.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2013A-1
Estimation of Fault Resistance from Fault
Record Data
September 2013
This report presents the results of an APIC project on the estimation of fault
resistances. Representative fault resistance values are needed for establishing
proper distance relay settings for transmission line protections. In this project, an
algorithm to estimate the fault resistances from fault data recorded by relays or fault
recorders is developed. The algorithm has been verified through simulation and
experimental studies. More importantly, the algorithm has been applied to determine
the fault resistance values for over 50 short-circuit events experienced by the 130kV
and 230kV lines of Altalink. The results have revealed the general range of fault
resistances in the Altalink system. It was found that the fault resistances are less
than 5 ohm for the majority of events analysed.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2013A-2
Applying Temporary Grounds for
Trip Grounding
September 2013
Trip grounding is the practice of grounding a worksite for the safety of field workers. There are,
however, confusion and challenges with respect to this practice. For example, it is not clear as to
what constitutes an ‘acceptable’ trip grounding point for a worksite, how to ensure a grounding
arrangement performing its intended functions and so on. These concerns are especially true when
temporary grounding rods are used. The objective of this project is to address such concerns, clarify
the issues and recommend solutions for the APIC companies.
The project found that the main function or benefit of trip grounding at a worksite is to increase the
fault current, leading to reliable and faster activation of protective relays or fuses. The benefits of
reducing energized voltage, lowering ground potential rise and limiting equipment damage are very
limited and are often not dependable. The requirement for grounding resistance less than 20~25ohm
has been adopted by many utility companies. However, extensive literature search failed to find
documents or papers that provide scientific justifications for the threshold. It seems that the threshold
is established based on what can be achieved by a 3 meter grounding rods under typical and slightly
optimistic soil resistivity values.
Since the purpose of grounding a worksite is to activate the protection, trip grounding is essentially a
protection coordination issue. The threshold of grounding resistance shall be established according to
the system impedance characteristics, the relay operation characteristics, and proper margin of errors.
Based on the measured grounding resistance data and soil resistivity characteristics collected by this
project, the coordination between trip grounding and existing protection schemes is not dependable.
For example, trip grounding provides a false sense of safety for about 15% worksites or higher. This
work also revealed that increasing fault current to activate protection is just a means, not the goal, of
trip grounding. In fact, increasing fault current is highly undesirable from various safety perspectives
such as arc-flash, step voltage and conductor whipping.
This report also presents some short, medium and long term solutions to the problems faced by the
trip grounding practice. The basic consideration of these solutions is to increase or ensure proper
coordination between grounding and protection.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2012A-1
An Investigation on the Effectiveness of Equipotential Bonding Mat
May 2013
This report provides technical and scientific information that APIC companies may
use to determine work practices and procedures associated with the use of portable
equipotential bonding mats (or simply called “bonding mats” or “mats”). The bonding
mats are used, for example, by utility workers during hydro excavation activities to
create equipotential zones at work sites. The main findings of the project are
summarized as follows:
- The portable bonding mat with its current design cannot create an acceptable
equipotential zone, from the perspective safe touch/step voltages. This finding is
valid regardless of whether the mat is bonded to a grounding structure or not.
The scientific reason behind the above findings is the following: an array of
meshed conductors laid on the ground surface cannot equalize the surface
potential to an acceptable level when they are energized.
- The specifications for designing, testing and inspecting the mats need
improvement. It is not clear what the technical justifications for some of the
specifications are. This report has shown how to establish proper specifications
and test procedures.
- Since the mat cannot create an equipotential zone but it can bring high voltage
closer to a worker under certain energization scenarios, the use of the mat could
actually increase electric risk to workers.
- The mats can be improved in two ways. The first is to make the fabric layer
dielectric and the other is to reduce the mesh size. Only the second option may
lead to the creation of (approximate) equipotential zone.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2012A-7
Low Frequency Magnetic Field Measurement of Utility Revenue Meters
and Home Appliances
February 2013
This report documents the findings on the Magnetic Field (B-field) measurement
results for utility revenue meters and common electrical appliances. Some Albertans
are concerned about the Electromagnetic Field (EMF) produced by utility revenue
meters. The University of Alberta, sponsored by the Alberta Power Industry
Consortium, initiated a project to help addressing this concern. The approach is to
measure, analyze and compare the low frequency magnetic field at homes with and
without revenue meters.
A magnetic field measurement system was developed for this project. B-field
emissions at five residential locations (four houses and one apartment) were
measured. The B-fields generated by 22 common electrical appliances were also
measured. The data are analyzed and compared. The main conclusion is that the
utility revenue meters do not produce additional consequential magnetic fields.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2012B-2
A Novel Zero-Sequence Harmonic Filter for Telephone Interference Mitigation
January 2013
The mass penetration of both energy efficient and consumer electronic devices in
homes have resulted in excessive harmonic distortions in residential feeders. One of
the consequences is the telephone interference problems experienced by three of
the APIC companies. This report presents a novel filter conceived to mitigate such
telephone interference problems. The idea is based on the concept of passive zero-
sequence harmonic filter modified with a double-tuning capability. This feature
makes it possible to trap two harmonics, such as the 9th and 15th harmonics, with
the filter. As a result, it is especially attractive to solving harmonic-caused telephone
interference problems. A practical method for sizing and designing the filter has also
been proposed. As an example application, the proposed filter package has been
applied through simulation studies to mitigate a telephone interference problem in a
feeder operated by EPCOR. Issues such as filter location, the number of filters
required and the effectiveness on filtering harmonics produced by distributed
residential loads have been investigated. The results show that the proposed filter is
a very promising technique to reduce zero sequence harmonics in general and to
mitigate telephone interference in particular.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2012B-5
Fault Current Contributions of Distributed
Generators and Their Impact on
Overcurrent Protection
December 2012
Distributed Generators (DGs) are known to contribute fault currents to their
interconnected power system. As a result, there is a concern that the DGs may
affect the coordination of overcurrent (O.C.) protection in a distribution system. This
may cause miscoordination among O.C. devices, nuisance tripping and relays’ reach
reduction (desensitization). This report presents the findings on the contributions of
DGs to fault currents and their probable impacts on the O.C. protection coordination.
Three types of DGs have been investigated. They are Inverter-based DGs (IBDGs),
Induction-Machine DGs (IMDGs) and Synchronous-Machine DGs (SMDGs). Fault
current contributions of each type are analyzed and simulations are presented to
support the analysis. The magnitude and duration of the currents are then assessed
from the perspective of relay coordination. This research found that the inverter-
based and the induction generator based DGs have negligible impact on overcurrent
protection. The synchronous machine based DGs are the only type that may cause
miscoordination when instantaneous, extremely inverse and, in some cases, inverse
overcurrent protection schemes are involved.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2012A-6
Harmonic Distortion Levels Measured at
The ENMAX Substations - 2012
October 2012
This report documents the findings on the harmonic voltage and current levels at
ENMAX Power Corporation (EPC) substations over a two year period. ENMAX is
interested in gaining an understanding on the harmonic levels in some of its
transmission substations and their trend in recent years. The University of Alberta
team initiated a project to help addressing this interest. The approach is to measure,
analyze and compare the harmonic currents and voltages at the substations of
interest to Enmax.
Harmonic voltage and current field measurements were carried out during a one-
week period in August 2012 at several ENMAX substations. This is the second time
to collect the data. Similar measurements were carried out in August 2011. The data
have been analyzed and compared in this report. The results include the daily
profiles as well as the statistical distributions of the harmonic voltage and current at
both phase and sequence domains.
This project did not study if the measured harmonic levels are high or low, or how
they compare with standards or other data. These are not the objectives of the
project.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 1.1
Identification of Harmonic Polluters
December 2011
Harmonic distortion is one of the main power quality problems for power system
utilities. Nowadays, there are many harmonic-generating loads in a given distribution
or sub-transmission system. These loads typically have comparable sizes and are
scattered all over the system. Developing methods and techniques to quantify the
harmonic impacts of the customers and the utility system, especially when a
harmonic problem occurs in a system, is highly important for power quality
management. Unfortunately, there are no viable techniques that can pinpoint which
customers cause harmonic distortions problem at a specific location of a system.
This report presents a data-based method and associated techniques for
determining the individual harmonic impact of multiple harmonic-producing loads
scattered in a power system. To facilitate technology transfer to the consortium
members, this method has been implemented in a software package, which is
available to APIC members. This reports covers following topics.
1) A quick tutorial of the provided software and two application examples.
2) The technical principal of the software.
3) Verification studies of the proposed methods and sensitivity analysis.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2011A-1
Harmonic Distortion Levels Measured at
The ENMAX Substations - 2011
October 2011
This report documents the findings on the harmonic voltage and current levels at
ENMAX Power Corporation (EPC) substations. ENMAX is concerned about the
harmonic impact of future HVDC converters to be implemented close to its
substations. The University of Alberta team initiated a project to help addressing this
concern. The approach is to measure, analyze and compare the harmonic currents
and voltages at substations close to the future converter stations before and after
the HVDC energization.
Harmonic voltage and current field measurements were carried out during a one-
week period in August 2011 at several ENMAX substations. This is the first time to
collect the data. Similar measurements are planned for next year (February 2012
and August 2012) and thereafter. The collected data have been analyzed and
presented through typical PQ indices and under different perspectives in order to
facilitate comparison with future field measurements. The results include the daily
profiles as well as the statistical distributions of the harmonic voltage and current at
both phase and sequence domains. Comparative harmonic level analysis will be
conducted after collecting more data in the future.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 3.3 (Task 2)
Modelling of Variable Frequency Drives for
Power System Dynamic Studies
Part 1: Implication of VFD Trip Characteristics on Dynamic Simulation
August 2011
Variable Frequency Drives (VFDs) are widely used in various industrial applications
and make an increasingly large portion of total loads in industrial facilities. However,
dynamic models of VFDs are currently not available for power system dynamic
studies.
This report presents the first set of research results on the subject of developing
models of VFDs for power system dynamic studies. It clarifies how a VFD responds
to voltage sags. Voltage sags occur when power system experiences short-circuit
faults, which is typically the starting point of power system dynamic simulation. This
research shows that VFDs will trip when they experience a relatively large voltage
sag (>20% - 30% voltage drop). As a result, there is no need to include VFDs in
dynamic studies under such conditions. Based on the finding, a simple procedure to
determine if a VFD needs to be included for dynamic studies is proposed and
presented in this report.
How to model VFDs when they experience mild voltage disturbances is still under
investigation.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 1.2
Advanced Load Shedding Scheme
April 2011
This project investigates an advanced load shedding scheme for the Alberta Integrated Electric
System (AIES). Based on the experiences of existing load shedding schemes and the advancement
of power system communication technologies, an event-driven load shedding scheme is proposed. In
this scheme, load shedding is triggered by outage events reported by the SCADA system or other
means and is initiated from the control center. The locations and amounts of loads to shed are based
on pre-established shedding tables. This is similar to the transfer trip scheme but it is done on a
system-wide scale and the settings are adjusted continuously according to the system conditions. A
design procedure for the proposed scheme has been developed through a series of analytical and
simulation studies. The main findings of this project are summarized as follows:
- An extensive review on the industry implemented load shedding schemes and on the operation
conditions of AIES suggests that an event-driven load shedding strategy is the most attractive
option for AESO.
- The load shedding locations can be obtained by following the proposed planning studies. The
planning studies also provides a set of load shedding actions, including load shedding locations,
amount, and maximum allowed time-delay for each critical contingency.
- The load shedding amount will be updated online by using the established system-condition
based tuning procedure. The tuning process can operate in a time cycle or be manually triggered
by the system operator or automatically triggered by the user-defined criteria.
- The maximum allowed time-delay of the load shedding actions is evaluated through time domain
simulation. If adjustments are needed for time delays, a bisection search method has been
proposed to find the proper values.
- A python-based add-on program for PSS/E has been developed by this project to facilitate
designing and tuning the event-driven load shedding rules. An event-driven load shedding
example on the AIES is given at the end of the report to illustrate how to use the python add-on in
PSS/E.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2.2 (Task 2)
Assessment and Mitigation of Harmonics in Power Distribution Systems
Task 2: Telephone Interference Encountered in an ATCO Distribution System
December 2010
This report documents the findings on the telephone interference problem in the
Goodfare area supplied by ATCO Electric. The problem was investigated through
field measurements and computer simulation studies. The project found that the
telephone interference problem was caused by distributed harmonic sources
residing in the residential houses. The harmonic currents injected by these loads
collectively lead to a high level of zero sequence 9th harmonic current flowing in
ATCO feeder 5L405. A comparative analysis of the results measured from different
feeders and from extensive harmonic simulations indicates that the high zero
sequence harmonic current distortions not unique to feeder 5L405. It seems that the
electrical nature of present-day home appliances have resulted in wide-spread
increase of zero sequence harmonics in residential feeders. A rough estimate is that
each 1 MW load (at 25kV) will increase the power line IT by 170A. Both power and
telephone companies need to adjust their expectations on the power quality levels of
residential feeders and to develop a harmonic management strategy accordingly.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2.2 (Task 3)
Assessment and Mitigation of Harmonics
in Power Distribution Systems
Task 3: Telephone Interference Encountered in EPCOR Summer Side Area
August 2010
This report documents the findings on the telephone interference problem along the 41st Ave SW in
Edmonton and its utility-side solutions. The problem was investigated through field measurements
and simulation studies. Several days of field measurements were conducted in the area. With the
support of Telus, voltages induced on a telephone line have also been measured.
The field measurements revealed that the high IT levels measured have similar characteristic to other
residential feeders recorded in the past. There are no specific causes of high IT level unique to the
Summer Side feeders. The 9th harmonic was found to be the main contributor to the telephone
interference level. Further studies revealed that feeder 21SU is the main contributor to the telephone
interference problem along the 41 Ave.
Simulation studies have shown that improvements on grounding points (i.e. reducing grounding
resistances) and load balancing do not yield noticeable reduction on telephone interference level.
Eliminating broken neutral points in the zone parallel with the telephone circuit will reduce the
telephone interference level. Two types of tuned zero sequence filters, Yg/∆ transformer-based and
shunt capacitor-based, have been found effective to reduce the telephone interference level.
This project once again showed that the high IT levels have become a norm for residential feeders.
As confirmed by simulation results, such IT levels are actually expected. All residential feeders with
regular demand levels are very likely to exceed power IT limits specified for industrial customers. The
implication is that harmonics from home appliances have become a major source of harmonic
pollution in power systems and they shall become a serious concern to utility companies. Broader
strategies are needed to address the problem. As for the specific problem of telephone interference,
this project has presented some promising utility-side solutions. However, the final solution to each
problem needs to take into account the costs of both utility-side and telephone-side solution options.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2.1
Fault Detection in De-Energized Distribution Power Line
December 2009
Before reclosing the circuit breaker, a need exists to check if the downstream still
experiences a fault. A novel power electronics-based fault detection scheme has
been developed and verified in both theoretical analysis and computer simulation.
Compared to other existing methods, the proposal has three significant benefits: (1)
a controllable power electronics-based signal generator, (2) capability of detecting
different kinds of faults in a single device and (3) capability of distinguishing a fault
from a capacitor bank or a stalled motor.
To further investigate the performance of the proposal, a real-time lab test has been
carried out recently in the PDS-LAB. Instead of based on a real distribution line, the
voltage source for this test is from the 120V, 60Hz power outlet in the lab. All
parameters of the lab test circuit are therefore scaled down from the 25kV-based
computer simulation model. A thyristor is controlled to inject a detection signal to the
test circuit and both voltage and current pulses are captured. The corresponding
harmonic impedance is calculated from the analysis of the voltage and the current in
frequency domain. The effects of a stalled induction motor are also presented. At
last, the actual fault conditions (using tree branch and dirt) are tested and compared.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 1.3
Measuring the Load Model Parameters
December 2009
The objective of this project is to develop algorithms for the online measurement and
monitoring of power system load model parameters. In this report, the existing load
modelling algorithms in literature have been reviewed, the load parameter
measurement problem is formulated and solution algorithms are proposed. An
algorithm is proposed to detect the tap movement using the step change in voltage
waveform. The proposed tap change detection and load modelling algorithms have
been verified using several field measurements from different substations. Moreover,
sensitivity studies have been done to investigate the characteristics of the tap
movement. The results show that the proposed algorithm can fulfil the load model
parameter measurement requirements.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 3.3 (Task 1)
Modeling of Industrial Facilities for Power System Dynamic Studies
November 2009
Presently, models for industrial facilities are usually not available for the utility long-
term planning study and operation study. Such facilities typically draw large amounts
of power and have complex dynamic responses to power system disturbances.
Traditional load modeling approaches such as those based on load composition or
site measurement are not adequate to produce dynamic models for such facilities.
Extensive literature review indicates that no such work has been done or attempted
in the past.
In this project, a facility template based load modeling technique along with template
scaling/equivalence algorithms is proposed to solve the facility modeling problem.
Oil refinery facilities are used as an example to illustrate the proposed modeling
technique. The technique requires minimal user input and can be implemented in a
database program. A complete information has been provided for creating a
dynamic load model for oil refinery facilities.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 2.2 (Task 1)
Assessment and Mitigation of Harmonics
in Power Distribution Systems
Task 1: Telephone Interference Encountered in an EPCOR Distribution System
September 2009
This report documents the findings on the telephone interference problem in the Ellerslie Road are of
Edmonton. Objectives of the project are to develop techniques for assessing and troubleshooting
harmonic problems in residential feeders and to research filtering methods to mitigate the harmonics.
The project found that the 23E feeder’s telephone interference problem was caused by distributed
harmonic sources residing in the residential houses. The harmonic currents injected by these loads
collectively lead to a high level of zero sequence 9th and 15th harmonic currents flowing in the feeder.
The 9th harmonic is the main component resulting in the telephone interference. In addition, a 9th
harmonic resonance experienced by the feeder exasperated the problem. A comparative analysis of
the results measured from different feeders indicates that high harmonic current distortions are not
unique to feeder 23E. Almost all residential feeders have comparable harmonic current levels and
spectral characteristics. Some of the feeders exhibit a very high IT level. It is also found that
residential loads produce more zero sequence harmonics than commercial and industrial loads. In
view of these findings, the project developed a simple and approximate chart for APIC members to
check if a feeder may experience zero harmonic resonance.
In summary, this task has identified successfully the causes of the telephone interference problem in
the Ellerslie road area. The results further suggest that distributed harmonic sources in residential
loads have emerged as a major cause of harmonic concern in power distribution systems. The next
goal is to research techniques to mitigate such harmonic problems. Before this task is attempted,
however, we intend to investigate one more real case reported in the ATCO system. Such an
additional case study will help to confirm the above findings so mitigation solutions to be developed
will have general applications.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 3.1 (Task 2)
Truck-Grounding Issue Investigation
March 2009
This report is prepared to provide technical information that electric utility companies may use to
determine working practices and procedures for working with non-insulated vehicles in the vicinity of
primary energized overhead distribution lines. The report considers grounding, barricading and other
methods that may be used to prevent or minimize injuries due to inadvertent contact of the vehicle
and equipment with energized lines.
This project has identified four safety options for utility companies to consider (1) grounding, (2)
barricading, (3) using an isolation mat and (4) wearing insulating boots/gloves. The grounding option
has been narrowed down into two choices (1) grounding to the system neutral or rod and (2) no
grounding. A utility company may mix and match these options to create a safety package for the
workers. Table 5.1 summarizes all possible combinations for consideration by the project sponsors.
Table 5.1: Possible safety packages for consideration by utility companies
Package No. Grounding* Barricade Isolation mat Boots/Gloves
Combination of all options 1 Yes Yes Yes Yes
Combination of three options
2 Yes Yes Yes No
3 Yes Yes No Yes
4 Yes No Yes Yes
5 No Yes Yes Yes
Combination of two options
6 Yes Yes No No
7 Yes No Yes No
8 Yes No No Yes
9 No Yes Yes No
10 No Yes No Yes
11 No No Yes Yes
Individual option
12 Yes No No No
13 No Yes No No
14 No No Yes No
15 No No No Yes
*Means grounding to system neutral or rod
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 3.1 (Task 1)
Wire to Earth Voltage Comparative
Analysis for Underbuilt Circuits
January 2009
This report presents results on the GPR (ground potential rise) characteristics and values at the multi-
grounded line configuration where a distribution line is installed below a transmission line in the same
tower structure. The GPR results of such a configuration are compared to those associated with
common single circuit configurations. The results are obtained through extensive analytical studies
and computer simulations. The main findings are summarized below:
- The under-built MGN distribution line has no adverse effect on the shield potential rise (SPR) of
the corresponding transmission line, i.e. the maximum SPR does not increase when a D-line is
added. This is because the highest SPR is caused by T-line faults and the D-line configuration
has little impact on this value.
- The above conclusion is valid even if one considers the fact that a T-line normally has a much
shorter fault clearing time than a D-line. More specifically, as long as the fault current of a T-line is
1.76 times greater than the D-line fault current, the T-line fault caused GPR poses higher safety
risk than the (underbuilt MGN) D-line fault. This is partially due to the fact that the electrocution
risk to humans is in proportion only to the square root of the fault clearing time.
- The D-line neutral points will experience higher neutral potential rise (NPR) when a fault occurs in
the overbuilt transmission line and if the T-line fault current is about 2.5 times higher than the D-
line fault current. This is in comparison to the NPR produced by a D-line fault. Shield wire of the
T-line has little impact on the maximum NPR (produced by the T-line fault). However, bonding
can significantly increase the NPR to about 1.6 times greater than that of the unbonded case,
during T-lien to shield (tower) faults.
In conclusion, there is no evidence to support the concern that an underbuilt distribution line poses
additional GPR-related threats to the transmission line. On the other hand, the designers of the
underbuilt D-lines shall pay attention to the higher NPR which may occur when the overbuilt T-line
experiences a phase-to-shield, phase-to-tower or phase-to-ground fault.
39
Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 3.2
A Practical Guide for Motor Starting
Planning
October 2008
The power quality impact of motor starting is a concern to utility companies. This
concern is especially important in Alberta due to the presence of a large number of
industrial facilities and the relatively long distribution lines. Although there are
various ways to reduce the impact of motor starting, almost all of the solutions need
to be planned and designed before the motor and its facility are connected to the
system. Furthermore, new power quality standards such as the IEC flicker meter are
gaining acceptance and it has become necessary to consider these standards when
conducting the motor starting planning studies.
The objective of this report is to provide technical information to support the motor
starting planning study from the utility’s perspective. The report attempts to address
all key issues involved in the study and to provide practical ways for efficient motor
starting impact assessment. The topics covered by this report include: 1) power
quality issues associated with motor starting, 2) customer and utility side solutions to
the motor starting problems, 3) methods for motor starting study and 4) practical
tools for quick screening of motor starting problems. These practical tools, called
motor starting guideline charts, are developed according to the latest IEEE power
quality standards. They help a planning engineer quickly estimate if a motor
installation can cause voltage sag or voltage flicker problems. He or she can then
decide if detailed motor starting study is required.
40
Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 3.4
Determining Acceptable AIES System
Restoration Island Synchronizing
Parameters
August 2008
This project investigates the main technical issues associated with the re-synchronization of islanded
Alberta Integrated Electric System (AIES). It determines if the current synchronization relay settings
are adequate and recommends changes if required. Through a series of analytical and simulation
studies, the impact of each synchronization parameter on generators and overall system performance
has been identified. The study further established analytical methodologies for interpreting the
simulation results by revealing the nature and mechanism of the synchronization disturbances.
Synchronization protection settings for AIES are recommended. The main findings of this project are
summarized as follows:
- The generator-system synchronization produces the highest transients on the generators in
comparison with the island-island synchronization cases when same synchronization criteria are
used. The implication is that if one adopts the relay settings of generator-system synchronization
to island-island synchronization, the impact of the synchronization transients on the generators
will be less than that produced by the generator-system synchronization.
- The results further show that the island-island synchronizing angle can go as high as 20o while
the resulting impact on generators is still within those produced by the generator-system
synchronization conducted at 10o. A frequency different up to 0.3Hz during island-island
synchronization can be tolerated from the perspective of impact on the generators. From the
stability and implementation perspectives, however, it is more desirable to keep the frequency
deviation within the 0.067-0.1Hz range.
- The voltage magnitude difference has the lowest impact on all indices except for the sudden
change in generator terminal voltages and in generator reactive power. Although the sudden
voltage change is within 5% for most generators, generator units at bus #350 and 1482 need
special attention to prevent higher voltage change beyond 5% during synchronization.
41
Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 1.4
Measuring the Supply System Impedance
Parameters
August 2008
The objective of this project is to develop algorithms for the online monitoring and
measurement of power system equivalent circuit parameter, such as the supply
system impedances. In this report, the measurement problem is formulated and
solution algorithms are proposed. Practical issues encountered for impedance
determination are investigated and solutions are developed. The proposed method
has been verified using computer simulation studies and several field measurements.
The results show that the proposed algorithms can fulfil the impedance
measurement requirements.
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Alberta Power Industry Consortium http://www.ece.ualberta.ca/~apic/
Report No. 4.1
Survey of High-Impedance Fault Detection
Techniques
April 2008
High impedance faults usually occur at primary network level in electrical distribution
systems. They can be described as those faults which do not draw sufficient current
to be recognized and cleared by the over-current devices in common use in the
utility industry. Research on high impedance fault detection has been conducted for
decades. However, a complete solution has not yet been found. Not only is the
current too small, but also because distinguishing high impedance faults from normal
operations are very complicated as various normal operations unfortunately create
the similar transient as HIF. The development of high impedance fault detection
techniques is reviewed in this paper while individual techniques are analysed and
classified. Composite systems which are implemented to overcome the
disadvantage of single techniques are also introduced. Moreover, alternate solutions
including mechanical techniques and remote techniques are presented. Finally,
possible improvements are proposed at the end of this paper.