BEV 40603
POWER QUALITY
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WITH WISDOM WE EXPLORE
Lecturer’s Info
• PM Ir. Dr. Dur Muhammad Soomro
• +60-17-7356197
• dursoomro@uthm.edu.my
• QA-602-12
• Main Medium: AUTHOR UTHM
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Chapter 1: Introduction to Power Quality
(PQ)
1.1 Definition
1.2 PQ issues
1.3 Sources of PQ problems (pbs)
1.4 Effects of PQ pbs
1.5 CBEMA CURVES
1.6 PQ Standards
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WITH WISDOM WE EXPLORE
Power quality definitions (contd…)
What is PQ?
Different perspectives
Equipment designer
Electrical utility Industrial/ end-user
or manufacturer
“A perfect
“The power that
sinusoidal wave,
works for
with no variations
“V availability or whatever
in the V, and no
outage.” equipment the
noise present on
end-user is
the grounding
applying.”
system.”
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Power quality definitions (contd…)
More concise
definition:
IEEE Definition:
“PQ is asset of
“The concept of electrical boundaries
powering and that allows a piece of
grounding sensitive equipment to function
electronic equipment in its intended
in a manner suitable manner without
for the equipment.” significant loss of
performance or life
expectancy.”
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Power quality definitions (contd…)
Gerry Heydt: Roger Dugan,
Mark
“The measure,
analysis, and McGranaghan,
improvement of bus and Wayne Beaty:
voltage, usually a load “Any power problem
bus voltage, to manifested in V, I, and
maintain that voltage f deviations that
to be a sinusoid at results in failure or
rated voltage and mis-operation of
frequency.” customer equipment.”
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Power quality definitions (contd…)
SUPPLY/ UTILITY
What PQ?
PQ=Reliability
Why PQ?
- Loss of production
- Product damages Voltage
- Maintenance
Quality Current and PQ
- Hidden cost
frequency Quality
CONSUMERS/
LOADS
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Power Frequency (PF) Disturbance
Electromagnetic Interference (EMI)
Power System Transients
Electrostatic Discharge (ESD)
Power System Harmonics
Power Factor Correction (PFC)
Grounding and Bonding
Radio Frequency Interference (RFI)
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Reasons for concern with PQ
Complexity of industrial processes.
End-user equipment become more
sensitive to PQ due to many
microprocessor-based controls.
Power electronics equipment used
for enhancing system stability,
operation and efficiency. They are
major source of bad PQ and are
Large computer systems in many vulnerable to bad PQ as well.
businesses facilities.
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Recent sources of PQ problems
High efficiency
Modern load & adjustable-speed
Increased awareness
equipments are more motor drives and
of the PQ issues by
sensitive to PQ shunt capacitors
the end users.
variations. results in increasing
harmonic levels.
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Internal Cause External Cause
• Approximately 80% of electrical • About 20% of PQ problems
disturbances originate within a originate with the utility
business facility. transmission and distribution
• E.g. Large equipment start-up system.
or shutdown, Improper wiring • E.g. The most common cause is
and grounding, Overloaded a lightning strike; others
circuits or Harmonics Equipment failure, Vehicle
accidents, Weather conditions,
Neighboring business, and even
Normal operation of utility
equipment
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Sources of PQ problems causing Transients
Distribution System
• External:
• Lightning
• Car hitting poles
• Internal
• Switching Operations (Breakers,
Capacitors,…)
• Fault Clearing/Breaker Operations
Customer System
• External
• Lightning
• Internal:
• Arcing Devices
• Starting & Stopping Motors
• Breaker Operations
• Capacitor Switching
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PQ problems, causes, effects and mitigation
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Examples of disturbing loads
MPcontrolled
Computers Equipment
ASDs for Motors
High-intensity
Lighting
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Typical types of PQ (PQ Issues)
Typical
Power
Quality
Voltage Voltage Voltage
Harmonics Transients
Flicker Sag/Dip Swell
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Typical types of PQ (PQ Issues)
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Typical types of PQ (PQ Issues)
Interruption
The complete loss of voltage for a period of time.
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Typical types of PQ (PQ Issues)
Overvoltage
An RMS increase in the ac V, at the power f, for a duration greater than a few seconds.
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Typical types of PQ (PQ Issues)
Undervoltage
An RMS decrease in the ac V, at the power f, for a duration greater than a few seconds.
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Typical types of PQ (PQ Issues)
Voltage Swell
An RMS increase in the ac V, at the power f, for durations from a half-cycle to a few seconds.
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Typical types of PQ (PQ Issues)
Voltage Sag
An RMS reduction in the ac V, at the power f, for durations from a half-cycle to a few seconds.
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Typical types of PQ (PQ Issues)
Flicker
A repetitive variation of input voltage sufficient in duration to allow visual observation of a change
in electric light source intensity.
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Typical types of PQ (PQ Issues)
Impulse Transient
A sudden, non-power frequency change in the steady state voltage or current, which has a
unidirectional polarity (nsec to msec).
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Typical types of PQ (PQ Issues)
Oscillatory Transient
Sudden, non-power frequency change in the steady state voltage or current, that includes
both positive and negative polarity values (5 usec to 3 msec).
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Typical types of PQ (PQ Issues)
Low Frequency Oscillatory Transient
Sudden, non-power frequency (300 Hz and 900 Hz) change in the steady-state voltage or
current, that includes both positive and negative polarity values – usually caused by utility
capacitor switching (0.5 to 3 cycles).
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Sources of PQ Problems
High Frequency!
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Sources of PQ Problems
Low Frequency!
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Sources of PQ Problems
High Frequency!
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Sources of PQ Problems
Low Frequency!
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Sources/Causes of PQ Problems and
Their respective Solutions
Power Quality Typical Causes Example Solutions
Impulse Transient Lightning, Electrostatic Surge arresters, Filters,
discharge, Load switching. Isolation transformers.
Oscillatory Transient Line/ Cable switching, Surge arresters, Filters,
Capacitor switching. Isolation transformers.
Voltage Sags/ Swells Remote system faults. Ferroresonant
transformers, UPS.
Under/ Over Voltage Motor starting, Load variation. Voltage regulators,
Ferroresonant
transformers.
Harmonics Distortion Nonlinear load, System Active/ Passive Filters,
resonance. Transformer with zero
sequence components.
Voltage Flicker Intermittent loads, Motor Static Var systems.
starting, Arc Furnaces.
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Effects of PQ problems (Broadly)
Increased Outside
Equipment costs from consultant
malfunctions downtime expense
Excessive Increased
wear or maintenance,
premature repair time
failure of and expenses
equipment
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Why PQ Standards?
• To provide guidelines, recommendations, and limits to help and assure
compatibility between end use equipment and the system where it is
applied.
• To protect the utility and end user equipment from failing or mis-
operating when the V, I, or f deviates from normal.
• PQ standards provide this protection by setting measurable limits as to
how far the V, I, or f can deviate from normal.
• By setting these limits, PQ standards help utilities, and their customers
gain agreement as to what are acceptable and unacceptable levels of
service.
• To help the PQ industry compare the results of PQ measurements from
different instruments
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Role of Standards (contd…)
Standards
Organizatio
ns (IEEE,
Power ANSI)
Conditionin Research
g Organizatio
Equipment n
Manufactur
ers
Utility
Customer
Manufacturer
Architects/E
Consultants ngineerings
Facility
Monitoring Designers
Equipment
Manufactur
ers
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PQ
Standards
IEEE IEC ANSI
Institute of Electrical International American National
and Electronic Engineers Electrotechnical Standard Institute
Commission
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IEEE:
- Corporate office in New York City
- Formed in 1963 from the amalgamation of the American Institute of Electrical
Engineers and the Institute of Radio Engineers
- Objectives are the educational and technical advancement of electrical and
electronic engineering, telecommunication and computer engineering and
allied disciplines
- Serves as a major publisher of scientific journals and organizer of
conferences, workshops, and symposia
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IEC:
- Coined in 1980
- Members 43 countries
- Concerned mainly about standards that
will enhance international trade referring
to PQ standards called as an
electromagnetic compatibility (EMC)
standards
- Primary concern is the compatibility of
end-user equipment with the utility’s
electrical supply system
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ANSI:
- Private, Non profit organization that oversees the development of voluntary
consensus standards for products, services, processes, systems, and
personnel in the United States
- Coordinates U.S. standards with international standards so that American
products can be used worldwide
- Accredits standards that are developed by representatives of other standards
organizations, government agencies, consumer groups, companies, and
others
- Does not develop standards, but facilitates standards development by
qualified groups, like the IEEE
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IEEE 1159-2009
Standard
Table 2 —Categories and
typical characteristics of
power system
electromagnetic
phenomena
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IEC Standard
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In the 1970s, the Computer Business Equipment Manufacturers
Association (CBEMA) developed the curve
In the 1990s, the Information Technology Industry Council
(ITIC)
curve was developed by a working group of CBEMA. In recent
years, the ITIC curve has replaced the CBEMA curve.
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PQ STANDARDS
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END
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