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TRANSCRIPT
Grid Fundamentals
Participant Guide
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Contents
1 | Electric Fundamentals .................................................................................................................................. 5
2 | How to Build an Interconnected Power System .................................................................................... 41
3 | Power System Operations ......................................................................................................................... 73
4 | Regulation .................................................................................................................................................... 92
5 | Environment and the Grid ...................................................................................................................... 107
6 | Current Events .......................................................................................................................................... 115
Appendix A—Glossary .................................................................................................................................. 123
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1 | Electric Fundamentals
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1 | Electric Fundamentals
Regulatory Agencies
In the early days of electricity, power systems were small, local, isolated, and served pockets of customers. As
the systems grew and became large enough to merge, they could offer more power resources. At the same
time, if one system had disturbances, the whole system would be unstable. Then, in 1965, the Great Northeast
Blackout revealed just how much the system had grown without any standards for reliability. Participation in
reliability of the electric power system was voluntary. Because of the 1965 large-scale outage, the need for
consistent national standards was realized.
Today there are three main entities that set regulation and compliance.
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Federal Energy Regulatory Commission
The Federal Energy Regulatory Commission (FERC) was established in 1920 as the Federal Power Commission
(FPC) and reorganized in 1977 as the Federal Energy Regulatory Commission.
FERC:
• Is an independent agency that reports to the U.S. Department of
Energy (DOE)
• Regulates the interstate transmission of natural gas, oil, and high-
voltage electricity. FERC uses civil penalties and other means against
energy organizations and individuals who violate FERC rules in
energy markets.
FERC is composed of five commissioners who are appointed by the president with the advice and consent of
the Senate. Commissioners serve five-year terms and have an equal vote on regulatory matters. There is no
review of FERC decisions by the president or Congress, therefore maintaining FERC’s independence as a
regulatory agency and providing fair and unbiased decisions. The commission is funded through costs
recovered by the fees from the industries it regulates.
Mission
To provide reliable, efficient, and sustainable energy for customers and to assist consumers in obtaining
reliable, efficient, and sustainable energy services at a reasonable cost through appropriate regulatory and
market means.
Delegates Authority
To manage its interstate electric reliability responsibilities, FERC delegates authority to an Electricity
Reliability Organization (ERO) called North American Electric Reliability Corporation (NERC).
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North American Electric Reliability Corporation
NERC was first formed in 1968 as the National Electric Reliability Council to promote the reliability of the bulk
power system. In 1981, NERC changed its name to the North American Electricity Council. In 2006 NERC
became the electric reliability organization (ERO) for North America, subject to oversight from FERC. In 2007,
NERC changed its name to the North American Electric Reliability Corporation.
NERC oversees six Regional Entities.
NERC oversees delegated authority with six Regional Entities covering the contiguous United States, Canada,
and part of Baja California, Mexico:
• Midwest Reliability
Organization (MRO)
• Northeast Power Coordinating
Council (NPCC)
• ReliabilityFirst (RF)
• SERC Reliability Corporation
(SERC)
• Southwest Power Pool (SPP)
• Texas Reliability Entity (TRE)
• WECC
Mission
To ensure the reliability and security of the
bulk electric system in North America. To achieve that NERC:
• Develops and enforces reliability standards;
• Annually assesses seasonal and long-term reliability;
• Monitors bulk electric system through system awareness; and
• Educates and trains industry personnel.
Delegates Authority
To manage its electric reliability responsibilities, NERC delegates authority to the Western Electricity
Coordinating Council (WECC) as a Regional Entity (RE) to oversee the Western Interconnection.
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Western Electricity Coordinating Council
In 1967, utility executives formed the Western Systems
Coordinating Council (WSCC) to promote reliability by
bringing the region’s planning and operating coordination
activities under one organization. The WSCC technical staff
was established in 1971 to perform planning studies and
coordinate WSCC committee activities. The WSCC
Dispatcher Training Program was established in 1981 to give
system operator training.
WECC was formed on April 18, 2002, by the merger of the
Western Systems Coordinating Council (WSCC), and two
regional transmission associates: The Southwest Regional
Transmission Association (SWRTA) and the Western
Regional Transmission Association (WRTA).
In 2007, WECC was designated as the Regional Entity for the
Western Interconnection responsible for compliance
monitoring. In addition, WECC was to provide an environment for development of reliability
standards and the coordination of the operating and planning activities of its members.
What is WECC?
Incorporated: 2002
Business: 501(c)(4) not-for profit a social welfare organization
Board of Directors: 9 Members, Independent
Employees: 140
Members: 364
Offices: Salt Lake City, UT, and Vancouver, WA
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Who is WECC?
• Largest of six Regional Entities
• Service territory
o Canada (Alberta and British Columbia)
o Northern portion of Baja California, Mexico
• All or portions of the 14 western United States
Governance
• Board of Directors
• Committees
o Operating Committee (OC)
o Reliability Assessment Committee (RAC)
o Market Interface Committee (MIC)
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This section introduces basic electrical forces, quantities, and components. The focus of this section is:
• What difference does electricity make?
• Physics of electricity
This section introduces basic electrical forces, quantities, and components. The focus of this section is:
• What difference does electricity make?
• Physics of electricity
What Difference Does Electricity Make?
“Just imagine, for a minute, life without energy. You don’t have a way to run a laptop, mobile phone, TV, or video games.
You don’t have lights, heat, air conditioning, or even the Internet to read this letter. About 1.3 billion people—18 percent
of the world’s population—don’t need to imagine. That’s what life is like for them every day.”—Bill Gates
The Great Northeast Blackout of 2003
Cause:
Heavy loads due to heat, state estimator not operating, alarm systems not working, lines sagging into trees,
• Lack of communication
• Affected: 50 million people
• 30 hours without electricity
“Electricity is what keeps our society tethered to modern times. Taking down [the] grid would scatter millions of
Americans in a desperate search for light, [we would] tumble back into something approximating the mid-nineteenth
century.”—Ted Koppel
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Electricity Through Time
Inventor Invention
1752 Benjamin Franklin Lightning = Electricity
1800 Alessandro Volta Battery
1820 Hans Oersted/ Andre
Amp
Relation to Magnetism
1826 Georg Ohm V = I x R
1831 Michael Faraday Electromagnetic Induction
1837 Thomas Davenport Electric Motor
1844 Samuel Morse Telegraph
1860 James Maxwell Mathematical Theory
1876 Brush Electric Motor
1876 Alexander Bell Telephone
1879 Thomas Edison Light Bulb
1883 Nikola Tesla Transformer/3 phase
1893 George
Westinghouse
Chicago World’s Fair
1897 Guglielmo Marconi Radio
1936 America Hoover Dam
1946 Pres Eckert, John
Mauchly
ENIAC Computers
1947 Bell Laboratories Transistor
1954 Russia Nuclear Power Plant
1962 USA Telstar
1954 Texas Instruments Transistor Radio
1960 Gordon Gould Laser
1965 Northeast Blackout Northeast Blackout
1991 Tim Berners-Lee World Wide Web
1994 Isamu Akasaki,
Hiroshi Amano, and Shuji
Nakamura
Blue LED
2007 Apple iPhone
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Evolution of the North American Electric System
The development of the electric utility industry provides insight into how the electric system is operated
today. Following is a timeline to illustrate the milestones of the electric power grid and its regulation.
1880s
The “War of the Currents” between Thomas Edison (Direct
Current) and Nikola Tesla (Alternating Current) is in full
competition.
1889
The first long-distance
transmission of DC
electricity in the United
States was switched on at
Willamette Falls Station in Oregon City, Oregon.
1890
The Willamette Falls Station DC power system was destroyed by
flood.
1891
The Willamette Falls Station was replaced with an AC power
system travelling 14 miles into Portland.
1920
Congress establishes the FPC to coordinate
hydroelectric projects under federal control. No
standards are in place.
1928
Congress gives the FPC funds and the FPC
expands to regulate natural gas, oil, and electricity.
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1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
1960s
Because of the FPC's expanded jurisdiction, the nation faced an energy crisis with chronic brownouts in
the 1960s and the OPEC embargo in the 1970s. This called for re-organization of the FPC which
happened in 1977.
1963
There are no standards or regulation of the electric power
system. An informal and voluntary organization of operating
personnel called the North American Power Systems
Interconnection Committee (NAPSIC) is formed (later to
become NERC) to coordinate the Bulk-Power System in the
United States and Canada. Seven interconnected transmission
systems are connected to form the largest electricity grid in
the world.
1965 The Great Northeast Blackout
November, New York City, the power goes out for 30 million
people, stranding 600,000–800,000 commuters in the subway.
Cause: Maintenance incorrectly setting a protective relay much
lower than its capacity. The originating substation tripped off,
overloading the next substation and what followed was a cascade of
events as power stations tripped off to protect their equipment.
Effect: Power was out for 30 million people in northeastern Canada and the United States. 20,000 MW
of load was lost for 13 hours.
Findings and Recommendations: The FPC led an investigation and made four recommendations.
1. Develop a system of controls to prevent one failure from cascading to shut down the whole
grid.
2. Ensure all emergency services have backup lighting systems so that hospitals, subways, etc.
have emergency lighting.
3. Establish a council on power coordination of representatives from Regional Entities to discuss
inter-regional coordination.Establish a National Electric Reliability Council (NERC).
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1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
1967
The Western Systems Coordinating Council (WSCC) is formed by 40
power systems as a trade organization. The WSCC becomes WECC 35
years later in 2002.
1968
June 1, the NERC is established by the electricity industry in response to the 1965 blackout and the
recommendation of the FPC. Nine regional reliability organizations are formed under NERC. Also
formed are regional planning coordination guides. The utilities maintain and practice voluntary
NAPSIC operating criteria and guidelines.
1970s
The nation faces an energy crisis
with chronic brownouts and the
OPEC embargo calling for a
reorganization of the FPC, which
happens in 1977. Environmentalism
reached new heights during the
crisis. Various acts of legislation
sought to redefine America’s
relationship to fossil fuels and other
sources of energy.
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1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
1977 New York Blackout
It is 12 years later, July 13–14, and New York City has another
blackout.
Cause: Two lightning strikes overload main transmission
lines. Auxiliary generation stations cannot be started because
the workers had gone home for the day. Additionally, a line
sagged into a tree and the combination resulted in all lines
tripping off in New York City.
Affect: 9 million people were without power. 6,000 MW of
load was lost with a 26-hour restoration time.
Findings and Recommendations: An investigation was done and three recommendations were made:
1. During a storm, increase local generation in case it is needed.
2. Install remote start-up of auxiliary turbines to allow operators to turn them on when no one is
in the facility.
3. Have contingency plans by using computers to help determine the most reliable actions to take.
1977
The New York blackout leads to the first limited reliability
provision in federal legislation. The legislation enables the
federal government to propose voluntary standards, an
authority never exercised.
The FPC is reorganized by Congress as the Federal Energy
Regulatory Commission (FERC) and reports to the
Department of Energy (DOE).
1979
Report is made to NERC by Joseph Swindler, former chair of the FPC, with recommendations with
respect to the substantive role of NERC, considering the Public Utility Regulatory Policy Act of 1978
(PURPA).
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1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
1980
NAPSIC becomes part of NERC, forming the NERC Operating Committee and bringing the reliability
roles of operations and planning together in one organization. NERC adopts NAPSIC operations
criteria and guides.
1981
NERC (National Electric Reliability Council) changes its name to the North American Electric Reliability
Council in recognition of Canada's participation and to reflect the broader scope of NERC’s
membership.
1987
NERC forms a committee to address terrorism and sabotage of
the electricity supply system at the urging of the National
Security Council and Department Of Energy.
1989 Hydro-Quebec Blackout
On March 13, Hydro-Quebec in
Canada experienced a geomagnetic
storm.
Cause: The terrain in this area acted
as a natural insulator and the
geomagnetically induced currents
(GIC) were not absorbed into the
ground. The energy moved to the
power lines where it destabilized the
voltage and tripped breakers in 90
seconds.
Effect: 6 million people were without
power and millions of dollars of equipment was damaged with a nine-hour restoration time.
Findings and Recommendations:
Develop a process of notification to communicate a geomagnetic storm
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1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
1992
NERC board of trustees states for the first time that conformance to NERC and regional reliability
policies, criteria, and guides should be mandatory to ensure reliability in one of six Agreements in
Principle adopted by the board. (At the time, NERC had no authority to enforce compliance with the
policies, criteria, and guides).
Building on the Agreements in Principle, NERC publishes "NERC 2000" a four-part action plan that
recommends mandatory compliance with NERC policies, criteria, and guides and a process for
addressing violations. "NERC 2000" encompasses policies for interconnected systems operation,
planning reliable bulk electric systems, membership, and dispute resolution.
1996
Two major blackouts in the western United States prompt the Western Systems Coordinating Council
(WSCC) to develop a regional Reliability Management System in which members enter voluntarily into
agreements with WSCC to pay fines if they violate certain reliability standards.
1997
The Electricity System Reliability Task Force established by the DOE and an independent Electric
Reliability Panel formed by NERC determine that grid reliability rules must be mandatory and
enforceable. They recommend the creation of an independent, audited, self-regulatory electric
reliability organization to develop and enforce reliability standards throughout North America. Both
groups conclude that federal legislation is necessary. NERC begins converting its planning policies,
criteria, and guides into standards.
1999
Broad coalition of industry, state, and consumer organizations propose legislation in the United States
that would create an electric reliability organization to develop and enforce mandatory reliability rules,
with oversight in the United States, by FERC.
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1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
2000
NERC is appointed as the electric utility industry's primary point of contact with the U.S. government
for national security and critical infrastructure protection issues. NERC establishes the Electricity Sector
Information Sharing and Analysis Center. Proposed reliability legislation first introduced in U.S.
Congress by Senator Slade Gorton of Washington.
2002
NERC operating policies and planning standards become mandatory and enforceable in Ontario.
WECC is formed from the WSCC when three regional transmission systems merge.
2003 The Northeast Blackout
On August 14, the largest-ever blackout in North
American history happens.
Cause: Heavy loads due to the heat; major
generating plants were off line for maintenance, the
state estimator was not operating, alarm systems
were not working, a line sags into a tree, and
operators did not communicate to neighboring
areas, which means they did not know to take
precautionary actions.
Affect: 50 million people out of power in Ontario and the United States. 60,000 MW of load was lost
and a 30-hour restoration time.
Findings and Recommendations
Lack of planning and situational awareness led to the following recommendations:
1. Standards—Implement mandatory reliability standards, enforce the standards and fines for
noncompliance.
2. Training—Create operator specific training.
3. Improved monitoring—Improved situational awareness in control rooms.
4. Communication—Establish better communication between entities.
5. Tree trimming—Trees must be trimmed so they do not contact sagging power lines.
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1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
2004
Final report of the U.S.-Canada Power System
Outage Task force on the 2003 blackout
concludes the most important
recommendation for preventing future
blackouts, and for reducing the scope of those
that occur, is for the U.S. government to make
reliability standards mandatory and
enforceable.
2005
NERC Version 0 Reliability Standards become effective. Voluntary compliance expected as a matter of
good utility practice.
2005
Energy Policy Act of 2005 authorizes the creation of an audited, self-regulatory "electric reliability
organization" that would span North America, with FERC oversight in the United States. The
legislation states that compliance with Reliability Standards would be mandatory and enforceable.
2006
April, NERC files an application with FERC to become the electric reliability organization in the United
States. NERC files 102 Reliability Standards with FERC.
July, FERC certifies NERC as the electric reliability organization for the United States.
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1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
2007
January, the North American Reliability Council becomes the North American Reliability Corporation.
The new entity has a large membership base representing a cross section of the industry.
March, FERC approves 83 NERC Reliability Standards, the first set of legally enforceable standards for
the U.S. Bulk-Power System, effective June 2007. FERC states that voluntary compliance with NERC's
additional standards should continue as a good utility practice.
April, FERC approves agreements by which NERC delegates its authority to monitor and enforce
compliance with NERC Reliability Standards in the United States to eight Regional Entities, with NERC
continuing in an oversight role. WECC is delegated authority by NERC as the Western Regional Entity.
June, compliance with approved NERC Reliability Standards becomes mandatory and enforceable in
the United States.
2008 South Florida Blackout
On February 8, 2008, a field protection engineer notified the control center when the primary source of
protection was removed, but did not notify the control center when the secondary level of protection
was removed. This was the first major event after the formation of NERC, the first investigation to
determine if the blackout was the result of noncompliance.
Cause: A transmission arc 20 seconds in duration caused a three-phase fault on a circuit breaker.
Because the primary and secondary protection was disabled, the circuit breaker was delayed by 1.7
seconds and the delay caused an imbalance in the southern Florida electric system with large swings in
frequency across the region. The frequency fluctuations were felt as far away as Canada.
Affect: 590,000 people were out of power. This was a loss 3,650 MW of power on 22 transmission lines
and 11 generators in the region with an efficient, three-hour restoration time.
Recommendations
1. Standards—Implement mandatory reliability standards, enforce the standards.
2. 24 recommendations were made to prevent recurrence of errors and to improve performance of all
NERC-affiliated organizations.
3. Florida Power and Light (FPL) was fined $25 million.
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1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
2011 Southwest Blackout
On September 8, 2011, a disturbance occurs in the Pacific
Southwest, leading to cascading outages.
Cause: This outage is an example of an error in one area of
the grid that rapidly spread to surrounding areas. The initial
error was from a switching operator who missed a step in
the switching procedure which caused the Hassayampa-
North Gila line to trip.
Affect: 2.7 million people in southern California (the entire city of San Diego), Arizona and Mexico’s
Baja California were without power. The restoration was efficiently completed in 12 hours.
Findings and Recommendations
FERC and NERC investigated and found the following:
1. The region was not operating securely in an N-1 condition.
2. Lack of operations planning. Improve sharing of data and the use of real time modeling and
contingency planning to anticipate outcomes.
3. Lack of communication and, therefore, situational awareness. Improve situational awareness of
real-time conditions by improving communication between Western Interconnection entities.
4. Overreliance on real-time tools, State Estimators, and Real-Time Contingency Analysis (RTCA)
tools, which do not always operate properly. Review tools to be sure they include all systems
critical to the regions reliability.
2012
FERC and NERC release report of the Arizona-Southern California Outages of September 8, 2011.
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Physics of Electricity
Understanding the basic forces and components of electricity will build a foundation for comprehending and
predicting how electrical equipment and the power system will operate.
This section includes:
• Voltage
• Current
• Power and Energy
• Electromagnetics
• Circuit Components
• Circuit Analysis
• Alternating Current (AC)
Atoms, Electrons, and Charge
Matter is composed of atoms, which in turn are made of negative charged electrons, positive charged protons,
and neutral neutrons. Electricity is the phenomenon associated with charges and movement of charged
particles and the forces they create.
Maxwell’s Equations
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Voltage
An electric field exists around any charged object. The electric field
exerts a force on any other charged object. Like charges repel
while opposite charges attract.
Voltage (V) is a measure of electrical pressure—how far will the
spark jump?
Unit of Measurement: Volts (V) For example, a transmission line
may operate at 138,000 volts or 138 kV.
Sample Voltage Levels
AA Battery 1.5 v
Car Battery 12 v
Household 120 v
Distribution Feeder
Circuit
12.47 kV
High Voltage Line 47 kV to 500 kV
Lightning 1,000,000 + volts
Current
Current is the movement of charge through a conductor.
Electrons carry the charge.
Current (I) is a measure of how much charge passes a point
in a second.
Unit of Measurement: Amperes or Amps (A). For example,
a large 1272MCM aluminum conductor (about 1 inch in
diameter) can carry about 1,200 amps.
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Cell phone battery charger 5/1000 Amps = 5 mA = (5
mil-amps)
Sensation .2–.5 mA
Let-go threshold 5 mA
Potentially lethal 50 mA
40-watt incandescent light
bulb
.33 Amps
Toaster 10 Amps
Car Starter Motor 100+ Amps
Transmission line
conductor
1,000 Amps
Lightning Bolt or Ground
Fault
20,000+ Amps
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Check your Knowledge
1. What is voltage?
2. What is current?
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Power and Energy
Power and Energy are ways to measure how much work can be done with electricity. Work is a concept for
describing things such as creating heat or turning motors. When we perform work over time, we use energy.
Power (P) is the rate at which work can be performed and is the product of Voltage and Current.
Unit of Measurement: Watts (W)
Power = Voltage x Current 𝑷 = 𝑽 ∗ 𝑰
One horsepower is 745 watts. For example, a large generator may produce 500,000,000 watts or 500 MW.
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Sample Power Calculation
Using the formula for power and substituting the known values, we have:
𝑃 = 𝑉𝐼
𝑃 = (120 𝑉) (10 𝐴)
𝑃 = 1,200 𝑊𝑎𝑡𝑡s
Example Power Use
Small light bulb 40 watts
Toaster 1,200 watts or
1 kilowatt (1 kW)
Household 5–10 kW
One horsepower 746 watts
(.746 kW)
Wind turbine 2,000 kW or
2.0 Megawatts (MW)
Combined Cycle Power Plant 500 MW
Watts and Watt-hours
A “watt” is instantaneous value. It is the
power being used at any given time.
A “watt hour” indicates how much
energy is used over time.
Watt x Time (in hours) = watt hours = energy
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Energy (kWh) is the sum of power delivered over time.
Unit of Measurement
Wholesale: Watt-seconds or Joules. The measurement for wholesale power is too small for utility
applications where energy is typically measured in thousands of watt-hours, or kWh.
Retail Consumption: Kilowatts x Time (in hours) = Kilowatt hours (kWh).
Energy = Power x Time
Watt-hours = Watts x Hours
1 kWh = 1,000 Watts x Hours
33.4 kWh = 1 Gallon Gas
Example:
5,000 watts used for 3 hours
5,000 watts = 5 kW
5 kW x 3 hours = 15 kWh
Customers are billed $0.07 to $0.15 per kWh.
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Electromagnetics
Electromagnetism is magnetism produced by an electric current, and electric
current produced by a changing magnetic field.
• Magnetic Field
• Current-Induced
Electric Field
• Magnetic-Induced
Electric Field
Characteristics of Electromagnetics:
• Wherever an electric current exists, a magnetic field
also exists.
• Whenever there is a change in a magnetic field, it
creates a circulating electric field.
• The magnetic field carries the invisible force of
magnetism.
• The magnetic field surrounds the conductor.
• A wire moving within a magnetic field will have a
voltage induced within the wire—this is how a
generator operates.
Electromagnetic Induction creates a voltage or current in a conductor when a magnetic field changes.
Whenever current flows through a conductor, a magnetic field is created around the conductor.
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Check Your Knowledge
1. What is power?
2. What is energy?
3. How do you create electricity with a magnet?
4. How do you create a magnet with electricity?
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Electric Circuit Components
This section includes:
• Conductors and Insulators
• Resistors
• Capacitors
• Batteries
• Inductors
• Generators
• Transformers
Conductors and Insulators
In some materials, electrons can move easily from atom to atom. These materials are called Conductors. Other
materials do not allow electrons to move between atoms. These materials are called Insulators.
Insulators Conductors
Air Copper, Aluminum
Dirt Dirt
Rubber Water
Plastic Other metals
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Resistors
Resistance (R)
Unit of measurement: Ohms
A resistor is composed of a measured length of high-
resistance material. Resistors oppose the flow of electrical
current and provide resistance to a circuit. This is sometimes
called impedance.
Resistance depends on:
Resistivity—Conducting material has very low resistivity, insulators have very high resistivity.
Length—Decreasing the material's length decreases the resistance.
Cross-sectional area—Increasing the material's cross-sectional area decreases the resistance.
Temperature—The hotter the wire, the more resistance it exhibits.
Resistors convert electric energy into heat. A transmission line is a resistor.
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Capacitors
Unit of measurement: Farads
Capacitance (C)
• Oppose change in voltage
• Store electrical charge and come in all shapes and sizes.
• Are used to INCREASE voltage
• Are composed of two plates of metal foil separated by
an insulating “dielectric” material. The flow of current
builds charge on the plates.
Batteries
A battery uses chemical energy to produce electric energy. A battery is composed of one or more pairs of
electrodes—each with different material separated by a chemical solution or “electrolyte.” The electrodes have
different “electron affinities,” i.e., one element “wants” the electrons more than the other.
Chemical Battery Operation
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Inductors
Unit of measurement: Henrys
Inductance (L)
• Opposes change in current.
• An inductor is composed of a coil of
wire or a long transmission line.
• An inductor provides inductance or
reactance.
• Inductors are used to REDUCE
voltage.
Generators
A generator is created by spinning a magnetic rotor past a stationary winding (stator).
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Check Your Knowledge
Create a motor by—
• Winding a coil to make an electromagnet to be a rotor.
It must have:
• A complete circuit
• A strong stator magnet
• A balanced rotor
• Good clearance
Watch out for heat, friction, and battery life.
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Transformer
A transformer changes high voltage to low voltage, enables high-voltage transmission of power, and works
only with Alternating Current (AC).
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Circuit Analysis
Ohms Law
Ohm’s Law defines the relationship between voltage, current, and resistance. It applies to both AC and DC
systems.
Voltage = Current times Resistance
V = I X
R
Where:
V = Voltage in Volts
I = Current in Amps
R = Resistance in Ohms
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Symbols
Conductors and Insulators
Resistors
Capacitors
Batteries
Inductors
Generators
Transformers
Transmission Line Electrical Model
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Reactive Impedance in Lines
• Reactance
• Voltage Drop
• Volt-Amps-Reactive = VARS
• Induced Voltages
Series and Parallel
A series circuit is a circuit that has only one path for current to flow.
A parallel circuit is a circuit that has more than one path for current to flow.
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Check your Knowledge
Why does a utility person need to know about?
• Voltage
• Current
• Power and Energy
• Electromagnetics
• Circuit Components
• Circuit Analysis
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Alternating Current
In this section, you will learn the difference between Alternating and Direct Current, and where and why each
is used. Topics include:
• Generating AC Current
• Sine waves
• RMS values
• Phase relationship
• Right triangle relationships
• Impedance–resistance, inductance, capacitance
Direct Current (DC) flows in one direction in a circuit. Early inventors such as Thomas Edison used and were
advocates for DC. Direct current is typically produced by a battery, or a rectifying power supply. Many
electronic devices such as radios, computers, LEDs, cell phones, and televisions use DC. Since power from a
wall outlet is alternating current, many of these devices contain an adapter or internal power supply that
rectifies and smooths the AC current into DC.
Alternating Current (AC) periodically changes direction of flow and magnitude. AC current is easily
produced by a rotating generator. Nikola Tesla was an early inventor and advocate for AC power systems,
which eventually prevailed over Edison’s proposed DC systems. A major advantage of AC is that voltage can
be changed easily up or down using transformers. As the voltage is stepped up, the current steps down and
lower current results in lower losses and smaller conductors.
The changing voltage and current values produced by the rotation in the generator can be represented by sine
waves. Sine waves are characterized by:
• Cycle—one complete repetition
• Period (T)—the time required to complete one cycle
• Frequency (F)—the rate at which the cycles are
produced
• Frequency is measured in Hertz (Hz). One hertz
equals one cycle per second
• Amplitude
• Peak
• Peak-to-peak
• RMS (Effective Value)
• Phase Angle is the angle difference between two
sine waves with the same frequency
1 | Electric Fundamentals
43
Sine Waves
Household Voltage
Generating 3-Phase Power
44
Phase Angle Between Two Generators
Power Factor = Real Power/Apparent Power
3-Phase Circuits
Power in AC Circuits
Real Power does the work; it does the heating, lighting, and turning off motors, etc., and is measured in
Watts.
Reactive Power supports magnetic and electric fields required for AC systems to function and is measured in
Volt-Amperes-Reactive (VAR).
Power in AC Circuits—Power Factor
Power factor = real power/apparent power
1 | Electric Fundamentals
45
Review
1. What difference does electricity make?
2. Physics of electricity
• Voltage
• Current
• Power and energy
• Electromagnetics
• Electric circuit components
• Circuit analysis
• Alternating Current
2 | How to Build an Interconnected Power System
46
2 | How to Build an Interconnected Power System
An interconnected electric power system consists of a lot of equipment that is all operated in synchronism.
This section covers system equipment and how it is used.
• Power transmission equipment
• Power generation
• What is an interconnection?
Power Transmission Equipment
Transmission equipment includes:
• Transmission lines
• Transformers
• Substation equipment
Power Transmission Lines
Transmission lines consist of:
• Conductors
• Towers
• Insulators
• Shield wires
• Rights-of-way
2 | How to Build an Interconnected Power System
47
The high-voltage lines that carry enormous amounts of power long distances are known as the transmission
system. Understanding the design, construction and operation of the system are essential to modern electric
grid. A transmission system consists of high-voltage power transmission lines that move power from remote
generation stations to large load centers.
Transmission lines are usually constructed using overhead conductors supported by large towers. These
transmission lines can span hundreds of miles. Transmission lines from various electrical utilities are
commonly interconnected to form a network or grid. This electrical grid improves reliability and creates
efficiency in the system.
48
Conductors
Conductors carry electricity. Transmission line conductors are made of copper, aluminum, or a combination of
aluminum (or copper) and steel. The most common conductor material is an aluminum conductor, steel
reinforced (ACSR) because it is light weight and low cost.
• The outer strands of aluminum carry most of the current
• The inner strands of steel provide physical strength for the conductor
• Conductors can be solid or stranded. Most utilities use stranded conductors because they are more flexible
All conductors are not capable of carrying the same amount of current. The ability to carry current depends on
size, material, and the ability to dissipate heat. Copper can carry more current for the same size of aluminum
conductor, but aluminum is less expensive. Overhead conductors are insulated by air.
Underground high-voltage transmission cables must be insulated with materials such as oil, gas, or rubber.
This increases the cost of the cable. The insulation and being buried also limits the cable’s current-carrying
capability because the heat cannot dissipate.
2 | How to Build an Interconnected Power System
49
Towers
Transmission towers support high-voltage transmission line conductors. Tower design must ensure there
is enough clearance between:
• Conductor phases
• The tower itself
• The ground and underlying objects like vegetation or structures
The distance between two towers, called a span, depends on the allowable sag. Sag is the amount the line
droops at the span's midpoint.
50
Insulators
Non-conducting—Insulators are non-conducting devices that attach the energized conductors to the support
tower. Insulators electrically isolate conductors from each other, as well as from the ground and support
towers.
Mechanical strength—The insulator must have enough mechanical strength to support the greatest loads
reasonably expected from ice and wind. Insulators must withstand mechanical abuse (such as gunfire and
thrown objects), lightning strikes, and power arcs without dropping the conductor.
Prevent flashover—Insulators prevent flashover under conditions of humidity, rain, ice, or snow; and with
dirt, salt, smoke, and other contaminants accumulating on the surface.
How insulators are made—Insulators are made of glass, polymer, or ceramic material. Most utilities use
porcelain for insulators because it has excellent insulation properties and mechanical strength. Some utilities
coat the porcelain with a glaze to provide a smooth surface from which contaminants can easily be removed by
rainfall or wash sprays.
Strings—Transmission line insulators consist of a string of insulator disks that are connected and suspended
from the support tower. Individual, bell-shaped insulator disks increase the distance that an electrical arc must
travel to get from the energized conductor to the support tower. This distance is called leakage distance.
Each insulator disk has metal connectors on the top and bottom to allow individual disks to be connected into
strings. Porcelain separates these connectors from each other to prevent short-circuiting the insulator.
The higher the voltage, the greater the number of disks required in each insulator string to maintain clearance.
Shield wires
Shield wires, mounted at the top of the support tower, protect the energized conductors from lightning strikes.
With conservative tower design, almost all lightning strikes to the transmission line hit a shield wire instead of
a line conductor.
Transmission lines need a conductive path from the shield wire to the ground to direct electrical energy from
the lighting strike to the ground.
• With a steel tower, the tower connects directly to the shield wire.
• With wood poles, ground wires run from the shield wire to the ground.
Sometimes the shield wires are also used for communications.
2 | How to Build an Interconnected Power System
51
Right-of-way (ROW)
Right-of-way is the land over which one or more
transmissions lines pass.
Right-of-way provides:
• Access to the line during construction and
subsequent line inspections, tests, and
maintenance; and
• Access to the vegetation under the line to
prevent it from growing up into the line and
causing short circuits.
Right-of-way must be wide enough to have adequate
clearance between the transmission line and trees and
buildings that are outside the right-of-way.
Transmission system definitions:
Extra-High Voltage (EHV) refers to transmission lines operating above 230 kV. These EHV lines form the
backbone of the Western Interconnect. Some common EHV line voltages are 345 kV, 500 kV, and 765 kV.
Ultra-High Voltage (UHV) refers to transmission lines above 800 kV. The use of UHV lines is still somewhat
experimental in North America.
High-Voltage Direct Current (HVDC) refers to transmission lines with voltages up to 1,000 kV pole to pole.
These are less common than the AC transmission lines, however, they do play a vital role in an interconnected
power system. The characteristics of EHV and HVDC lines will be discussed further in Module 7, Power
Transmission.
Electrical Characteristics of Lines
• Resistance → Losses
• Reactance → Voltage drop
• Reactance → Volt-Amps-Reactive (VAR)
• Induced voltages (in fences, railroad tracks, pipelines, etc.)
• Capacitance → Voltage rise
52
Check your Knowledge
1. What is the importance of insulators in transmission lines?
2. What considerations are there for conductors?
3. Why is it important to know electrical characteristics of a transmission line? (i.e., voltage, current,
resistance, reactance, capacitance, etc.)
2 | How to Build an Interconnected Power System
53
Transformers
Many different voltages are required to deliver power long distances and serve various equipment and
customer needs. A transformer is the component that changes from one voltage to another.
Transformers raise or reduce voltage to a usable level. For example, a transformer reduces high voltage down
to a usable level in a home.
How a Transformer Works: Magnetism and Electromagnetism
A transformer is made up of two or more conductors wound around a single magnetic core, usually iron. The
wound conductors, usually copper, are called windings.
How Windings Work:
• An alternating current in the coil causes an alternating magnetic flux in the core
• The magnetic flux in the core passes through another coil (the secondary winding), inducing an
alternating voltage in this coil
• The amount of induced voltage depends on four factors:
1. Core composition and shape
2. Number of turns in primary coil or winding
3. Number of turns in the secondary coil or winding
4. Primary voltage
54
Transformer Core
• A transformer core is made from carefully stacked pieces of steel sheet metal
• Magnetic flux travels through (permeates) the steel hundreds of times easier than through air
• The core is shaped to allow the maximum steel path for the flux to flow through with minimum air-gaps
• Individual sheets of steel reduce eddy currents between sheets
The core and the windings are mounted in a steel tank filled with mineral oil or some other liquid suitable for
insulating and cooling. Insulated bushings, usually mounted at the top of the tank, connect the windings to
other power system equipment.
2 | How to Build an Interconnected Power System
55
Transformer Turns Ratio
Voltage changes in the transformer are determined by
the turns ratio or windings ratio.
Types of Transformers
• Power Transformers
• Autotransformers
• Phase Shifting Transformers
• Instrument Transformers
• Distribution Transformers
Transformer Ratings
Oil to air (OA) New nomenclature is ONAN (meaning Oil—Natural Circulation, Air—Natural
Circulation)
Forced air (FA) New nomenclature is ONAF (meaning Oil—Natural Circulation, Air—Forced Circulation)
Forced-oil and air (FOA) New nomenclature is OFAF (meaning Oil—Forced Circulation, Air—Forced
Circulation)
56
Substation Equipment
Substations are critical facilities to the generation, transmission, and distribution of electrical power. One
general purpose for a substation is to localize all the necessary electrical equipment for an area into one site.
Power lines originate and terminate at substations. The size of a substation can vary greatly, depending on the
number of lines connecting to it, the voltages of incoming and outgoing lines, and the amount of equipment
contained within the site.
A substation usually includes a control house. A control house is used to protect sensitive equipment that
cannot be exposed to the elements. Substations often have a ground mat (or ground grid). A ground mat is a
system of grounded, buried conductors connected to all substation equipment (including the fence around the
substation). A properly installed grounding mat ensures that all equipment remains the same potential,
preventing an electric shock hazard. Ground grids also provide protection for overvoltage, which can damage
expensive substation equipment. A substation can be indoor or outdoor.
2 | How to Build an Interconnected Power System
57
Common equipment located within a substation:
• Bus
• Current Transformer
• Power Transformer
• Potential Transformer
• Circuit breaker
• Switch
• Capacitors
• Lightning arrestor
• Protective relays
• Meters
• Alarms
• Communication
58
Transmission Substation
A transmission substation is a facility where transmission lines terminate or connect to other transmission
lines. Transmission substations contain equipment to sectionalize the power system. These sectionalizing
points are necessary to isolate faults on system equipment, as well as remove equipment from service for
maintenance. Most transmission substations contain transformers to step down the high transmission system
voltages to lower sub-transmission voltages.
Sub-Transmission System
A sub-transmission system is an intermediate step between the
transmission system and the distribution system that supplies
electricity to customers.
Sub-transmission lines are energized with a lower voltage than
the EHV lines, typically ranging between 46 kV and 229 kV. One
of the greatest benefits of a sub-transmission system is that it does
not require the large "rights-of-way" required by EHV
transmission lines. Sub-transmission lines are also used to serve remote, small communities.
Sub-transmission systems are also beneficial if a generating station is near the load. In this case, the sub-
transmission lines can serve local distribution substations without the need for stepping up the voltage to EHV
levels.
Switching Station
Transmission substations that do not contain any transformers are referred to as switching stations.
These switching stations only serve as a sectionalizing point for a transmission system. Transmission
substations will be discussed in greater detail in Module 5, Substation Overview.
Distribution Substation
A distribution substation energizes the distribution system, which supplies power to customers.
Distribution substations contain power transformers that step down the transmission- or sub-transmission-line
voltage to the primary distribution voltage. Most utilities operate their distribution systems between 4 kV and
34.5 kV.
Utilities use circuit breakers within distribution substations to de-energize and re-energize individual
distribution circuits. These breakers are necessary to isolate faults on the system, or to remove the line from
service for maintenance.
2 | How to Build an Interconnected Power System
59
Substation Protection
System protection is important to protect the equipment in a substation and
elsewhere from damage to under or over equipment operating ratings.
Substation protection equipment and their functions include:
• Circuit breakers are big switches.
• Relays look at current and voltage.
• Relays decide when there is a problem on the system.
• Relays issue trip signals to circuit breakers.
• Circuit breakers open the circuit before things melt.
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Power Generation
A generating station supplies power to the electrical system. The power is produced using turbines which turn
large-scale generators, which generates alternating current (AC) at a frequency of 60 hertz. These turbines are
driven by steam, water, combustion gases, wind, and other forces.
This section covers:
• Generator components
• Thermal generators and sources of fuel
• Other generators
39%
26%
15%
8%
3%
3%
3%3%
Nameplate Capacity, 2015 (MW)
Gas 108,400 Hydro 71,645 Coal 39,090 Wind 22,859
Solar 9,513 Nuclear 7,679 Other Renewable 7,723 Other Thermal 1,843
2 | How to Build an Interconnected Power System
61
Each generator must operate in a manner that conforms to and supports the grid. Frequency must be
maintained at 60 Hz; this is a function of how many poles the rotor has and how fast the shaft spins.
A stand-alone generator may speed up or slow down in response to the balance between load and input
mechanical power. When operating on the grid, a synchronous generator must stay in step and adjust its
output and input mechanical power to match.
Generator Components
Generator components include:
• Stators
• Rotors
• Exciters
• Controls
• Turbines
Generating 3-Phase Power Waves
62
Stators and Rotors
A generator consists of a magnetized rotor spinning inside a set of stator windings. The rotor is an
electromagnet whose current is provided by the exciter through slip rings on the shaft. Input power comes
from a turbine or reciprocating engine via the input shaft.
The rotor of a motor is an electromagnet. When it is energized, it is repelled or attracted by surrounding
magnets. The slip rings and brushes energize the rotor; first one way, then the other.
Changing the magnetic field creates a current in a conductor—this is called electromagnetic induction. To
create a generator, combine these magnetic phenomena:
• Create a magnet using current through a coil of wire.
• Spin the magnet past another coil of wire to create a voltage in that coil.
When the generator circuit is not connected, the rotor can spin freely, however, when it is connected and
current begins to flow, the stator windings become magnets…that oppose the force that creates them.
Excitation System
• Supplies current to the rotor through brushes
• Turns the rotor into a spinning magnet
• Can vary current to affect voltage and VAR output
• Exciter current flows from the brushes to the slip rings on the rotor
2 | How to Build an Interconnected Power System
63
Generator Operating Characteristics
Generator characteristic curves show the operating limits of a generator.
V Curves show the relationship between Field Current and Armature Current for different power output
levels. Adjusting the field current (supplied by the exciter) changes the VAR output (power factor) of the
generator.
D Curves show the capability with different cooling levels.
64
Generator Controls
Generator controls allow generators to react to power system changes faster than a person could react. Those
controls include:
• Automatic Voltage Regulator (AVR)
• Automatic Generator Control (AGC)
• Power System Stabilizer (PSS)
• Digital Control System (DCS)
• Human Machine Interface (HMI)
• Supervisory Control and Data Acquisition (SCADA)
Types of Generators and Energy Sources
Turbine/Prime
Mover
Energy Sources Type of
Generator
Thermal/Steam
Steam Turbine
Combustion
Turbine
Internal
Combustion
Coal
Natural gas
Diesel
Nuclear
Solar
Geothermal
Biomass
Synchronous
Hydro Turbine Rivers Synchronous
Wind Turbine Wind Induction
Generator
Photons Solar Photovoltaic
Other Hydrogen/Natural
Gas
Fuel Cell
Wave Generation Ocean Induction
Generation
2 | How to Build an Interconnected Power System
65
Thermal Generators and Sources of Fuel
Steam Turbines
Turbines consist of a series of blades or fans attached to a rotating shaft. High pressure air, steam, or water
turns the blades as it passes to a low-pressure area. Efficiency is a function of the pressure difference from
front end to back end as well as how efficiently the design of the blades captures the energy.
Combustion—Compressed air and natural gas ignite
and combustion products expand through the turbine.
Combined Cycle—Uses both a gas and a steam turbine
together to produce up to 50 percent more electricity from
the same fuel than a traditional, simple-cycle plant. The
waste heat from the gas turbine is routed to the nearby steam
turbine, which generates extra power.
Internal Combustion
Not a turbine, but uses expanding combustion
products to move pistons, which rotate a shaft.
66
Thermal Energy Sources
Coal and Gas
Turbine/Prime Mover Energy Sources Energy Type
Thermal/Steam:
Steam Turbine
Combustion Turbine
Internal Combustion
Coal
Natural gas
Diesel
Nuclear
Solar
Geothermal
Biomass
Fossil
Fossil
Fossil
Nuclear
Renewable
Renewable
Renewable
Hydro Turbine Rivers Renewable
Wind Turbine Wind Renewable
Solar Solar Renewable
Fuel Cell Hydrogen/Natural
Gas
Mix
Wave Generation Ocean Renewable
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67
Nuclear Powered Generation Plant
Geothermal
Biomass
68
Hydro
High-pressure water from a
reservoir or river-fed pen-stock
turn the turbine.
Wind
Large fan-like blades catch the wind
and are pulled and pushed around
using advanced aeronautical design.
2 | How to Build an Interconnected Power System
69
Solar-Thermal
Solar—Photo-Voltaic (PV)
Diesel Fuel Cell
70
Check your Knowledge
1. What are the trade-offs between different generation types?
• Construction cost
• Fuel cost
• Renewable factors (i.e., solar, wind, etc.)
• Environment considerations
2 | How to Build an Interconnected Power System
71
What is an Interconnection?
The electric power system consists of many individual electric utilities that are electrically tied together and
are synchronized at a frequency of 60 Hz.
Building an interconnected system requires:
• Planning;
• Preparation;
• Standards;
• Communications; and
• Real-time monitoring.
72
3 | Power System Operations
73
3 | Power System Operations
Power system operations includes operating both the equipment as well as economic dispatch of power. This
section covers:
• Types of Load
• Load Characteristics
• Balancing Authority
• Balancing Tools and Measures
• System Operators
• Safety
• System Restoration
Types of Load
• Residential
• Commercial
• Industrial
• Agriculture
Load Obligations
• Firm
• Interruptible
• Contract
Appliances, 22%
Water Heating, 18%
Space Cooling, 9%
Lighting, 6%
Space Heating, 45%
Appliances Water Heating Space Cooling Lighting Space Heating
74
Load Characteristics
• On- vs. Off-peak
• Seasonal
• Daily
• Renewable
• Predicting load
Load Varies:
• Moment to moment
• Time of day
• Day of week
• Time of year
3 | Power System Operations
75
Load Forecasting
The “Duck Chart”
Load forecasting is done hourly, daily, weekly, monthly, yearly, and years ahead. Predicting load in relation to
weather and cultural trends is an ongoing challenge. Building transmission lines and generators in the next
two to 10 years is done by forecasting the needed load.
76
Check Your Knowledge
1. What are 4 types of load?
2. What is peak vs. off-peak load?
3. Why does load vary?
4. What things are considered when doing load forecasting?
5. How far in the future do we forecast load?
3 | Power System Operations
77
Balancing Authority
A balancing authority operates within the metered boundaries of their area and is responsible to:
• Maintain balance between loads, generation, and net interchange;
• Control frequency;
• Maintain reserves;
• Implement interchange transactions; and
• Minimize cost.
78
Balancing Authorities
AESO Alberta Electric System Operator
AVA Avista Corporation
AVGO Arlington Valley, LLC
AZPS Arizona Public Service Company
BANC Balancing Authority of Northern California
BCHA British Columbia Hydro Authority
BPAT Bonneville Power Administration - Transmission
CFE Comisión Federal de Electricidad
CHPD PUD No. 1 of Chelan County
CISO California Independent System Operator (CAISO)
DOPD PUD No. 1 of Douglas County
EPE El Paso Electric Company
GCPD PUD No. 2 of Grant County
GRID Gridforce Energy Management, LLC
GRIF Griffith Energy, LLC
HVPD New Harquahala Generating Company, LLC
IID Imperial Irrigation District
IPCO Idaho Power Company
LDWP Los Angeles Department of Water and Power
NEVP Nevada Power Company
NGW NaturEner Power Watch, LLC
NWMT NorthWestern Energy
PACE PacifiCorp East
PACW PacifiCorp West
PGE Portland General Electric
PGR Gila River Power, LP
PNM Public Service Company of New Mexico
PSCO Public Service Company of Colorado
PSE Puget Sound Energy
SCL Seattle City Light
SRP Salt River Project
TEPC Tucson Electric Power Company
TID Turlock Irrigation District
TPWR City of Tacoma, Department of Public Utilities
WACM Western Area Power Administration, Colorado-Missouri
Region
WALC Western Area Power Administration, Lower Colorado
Region
WAUW Western Area Power Administration, Upper Great Plains West
3 | Power System Operations
79
Balancing Tools and Measures
• Load and generation balancing
• Automatic Generation Control (AGC) basics
• Area Control Error (ACE)
• Frequency response
• Operating reserves
• Operating limits
• Interchange scheduling
Load/Generation Balance
Frequency control keeps the system in balance.
Purpose of Frequency Control: Protection
Frequency control protects equipment from being damaged by abnormal frequencies. For example, generators
will trip off. When generation is lost, coordinated dropping of load will keep frequency in balance.
80
Automatic Generation Control (AGC)
AGC is a system for adjusting the power output of generators in response to changes in the load to keep the
electric power system in balance.
AGC:
• Increases output when it sees low frequency
• Decrease output when it sees high frequency
• Governor action takes place without control center instruction
Area Control Error (ACE)
ACE measures whether a Balancing Authority is properly generating its MW requirements, which in turn
helps to control the interconnection frequency.
ACE Equation
ACE = (Actual – Scheduled – (Bias x (Actual Frequency – 60 Hz))
ACE = (NIA – NIS) – (10B x (FA - FS))
Negative ACE = under-generation
Positive ACE = over-generation
3 | Power System Operations
81
Sample AGC Response
Somewhere in the system, a generator trips…
• Stored energy (inertia) from all rotating mass in system acts to slow frequency decline…
• ACE equation tells the Automatic Generation (AGC) to increase generation…
• All generator governors act to restore frequency…
• AGC of deficient system eventually reacts to compensate for lost generation.
•
Off-Nominal Frequency Plan
When frequency deviates from 60 Hz…
1. AGC causes generators to respond…
2. Operator action…
• Routine generation changes
• Interruptible load curtailments
• Manual load shedding (coordinated throughout WECC)
3. Automatic relay action…
• Under-frequency load shedding
• Over-frequency load restoration
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Frequency Response
When there is a disturbance in the system, a frequency response sequence kicks in.
Operating Reserves
Electricity production is a “real-time” process. Extra generating capacity needs to be readily available:
• To replace lost generation or imports
• Supply load increases
• Used to meet the Disturbance Control Standard (DCS)
• Systems can meet requirements collectively
• Can create Reserve Sharing Groups
3 | Power System Operations
83
Operating Reserve Standards
BAL-002-WECC-2 Contingency Reserve Standard
The greater of either:
• Most severe single contingency;
• Three percent of load plus three percent of generation.
Composed of:
• Spinning (online generators with extra capacity)
• Contract
• Interruptible load
• Other resources
Reserve Sharing Groups
Reserve Sharing Groups consist of two or more Balancing Authorities that collectively maintain, allocate, and
supply operating reserves for use in recovering from contingencies within the group.
There are many types of Reserve Sharing Groups:
• Self-supply
• Market structure
o California ISO
• Reserve sharing groups
o Northwest Power Pool
o Desert Southwest Reserve Sharing Group
o Rocky Mountain Reserve Group
84
Operating Limits
Operating Limits vary by situation and by path.
• Power from generators to loads follows all available paths
• Most power flows over paths with least impedance
• Operating limits are in place to avoid overloads
• When a line opens, power flow redistributes almost immediately
• System is designed to handle contingencies of line tripping or lost generation
• Relays, Operators, or Special Protection Schemes (SPS or RAS) act to prevent equipment overloads
• Path Limits monitored are—
o Thermal limits;
o Stability limits; and
o Voltage limits.
• There is enforcement for operating limit violations
Electricity is a commodity.
• Must be used immediately as it is generated
• Power exchanges track pricing per location
• Power exchanges track pricing per time of the day (clearing as frequently as every five minutes)
• Because of the lack of inventory/storage, the price of electricity on the power markets can vary
dramatically:
o Day-ahead exchange;
o Intra-day exchange (a few hours ahead); and
o Real time.
3 | Power System Operations
85
FERC Orders 888/889: Transmission Service Fair Treatment
This order protects and promotes generation competition and enforces fair treatment of external users of the
transmission system. The order requires—
• Functional separation of merchant (power marketers) and transmission (power scheduler) functions;
• Transmission service to be equally available to all market players; and
• Transmission to be marketed via an OASIS (Open Access Same-time Information System)
A Day-in-the-Life of a Market
Ancillary Service
Ancillary services support the transmission of electric power from seller to purchaser.
• Scheduling and dispatch
• Reactive supply and voltage control
• Load regulation and frequency control
• Energy imbalance
• Operating reserves
• Energy loss compensation
Generation Market
(loads)
• Assess market
conditions
• Submits a
“willing to
purchase price”
• Looks for a
seller
Consumer Market
(producers)
Generation Market
(producers)
Generation Market
(producers)
• Assess market
conditions
• Submits an
“asking price”
(bid)
• Looks for a
buyer
• Assess market
conditions
• Submits an
“asking price”
(bid)
• Looks for a
buyer
• Assess market
conditions
• Submits an
“asking price”
(bid)
• Looks for a
buyer
86
Interchange Scheduling
How is Power Scheduled?
Example: How do we get 100 MW of power to flow from Balancing Authority A to B?
• A generates 100 MW more than its load.
• B generates 100 MW less than its load.
Excess MW from A serves the deficiency in B.
What is Scheduled Interchange?
3 | Power System Operations
87
Unscheduled Flow
The difference between actual and scheduled interchange is Unscheduled Flow (USF). USF is the phenomenon
by which power flows over paths other than its contract or scheduled paths. USF is a result of operating an
interconnected electric system in which many parallel paths exist for power flowing from sending points to
receiving points.
The magnitude of the USF on a given path will vary as a function of several factors. USF is a physical
byproduct of interconnected-system operation.
Some of the ways USF is managed is to use phase shifters, series capacitors, and curtail schedules that cause
USF.
88
Common Power Types in the Market
Firm
• Highest level of delivery priority
• Backed up by system-wide resources
Contingent
• Depends on availability of certain resources
• Cut before any firm deliveries are cut
Non-firm/Interruptible
• Lowest level of priority
• Highest likelihood of being cut
Power Scheduling
• Schedulers make transactions for the next day’s operation.
• Operators make real-time schedule adjustments as needed.
• In real-time, hourly schedule changes are ramped to smooth abrupt changes.
3 | Power System Operations
89
Transaction Tagging
Electronic Tagging (e-Tag) is the process that allows each transaction to:
• Be uniquely identified
• Identify all parties and transmission arrangements
• Facilitate timely schedule cuts if problems arise
After-the-Fact Accounting
Actual operation often differs from the original plan. Accounting
personnel unravel the changes from the prescheduled operation.
Markets 101
Decentralized
Power Markets
Centralized
Power Markets
Most common (Bilateral
markets)
Becoming increasingly common
(CAISO, AESO, PJM, MISO, ERCOT)
Individual sellers →
Brokers → Buyers
Marketplace- organized trade for power
Like a real estate deal Stock market like - Rules/framework
can vary—fairness and consistency is
key
Do not typically include
ancillary services but now,
they do…
Market products for ancillary services
(freq. or voltage support)
Transaction costs can vary
but offers flexibility
Goal is to reduce transaction costs but
market operator has enormous
discretion and “information.”
Transmission Markets and Service
FERC order 888/889 regulates an Open Access Same-Time market.
Energy Imbalance Market
Energy Imbalance Market (EIM) is simply an every-five-minute automatic version of manual dispatching that
was every 60 minutes. Before the EIM, typically, the same person bought and sold power. In the EIM market,
different people handle the market and operation.
90
Check Your Knowledge
1. What results when power does not travel on the scheduled path?
2. What is AGC?
3. How is frequency related to generation/load balance?
4. What is an e-Tag?
5. What is EIM?
3 | Power System Operations
91
System Operators
An electric system operator is an individual at a Control Center of a Balancing Authority, Transmission
Operator, or Reliability Coordinator, who operates or directs the operation of the Bulk Electric System (BES) in
real-time. As system information is brought into the control room, the system operator determines what
actions to take. Key responsibilities are monitoring:
• SCADA (Supervisory Control and Data
Acquisition);
• AGC (Automatic Generation Control);
• Generator status;
• Breaker and line status;
• Issuing clearances for system maintenance;
• System overloads;
• Situational awareness;
• State estimator;
• Contingency analysis;
• Economic dispatch;
• Interchange transaction scheduling; and
• Power system analysis.
1880s 1920s 1960s 1970s 1980s 1990s 2000s 2010s
92
Safety
Utilities are listed as a high-risk industry.
Safety is a main part of daily operation.
• Personnel safety
• Switching orders
• Clearance to work on equipment
• Restoration to service
System Restoration
A major disturbance can result in islanding, load
shedding, tripping of generation, and full or partial
blackout, and requires restoring the system back to
normal balance. Sometimes it requires restoring
multiple systems.
August 10, 1996 NW Disturbance
3 | Power System Operations
93
Causes of Major Disturbance
• Storms
• Earthquakes
• Equipment malfunction
• Inadequate system
• Operating errors
• Sabotage
• Combination of events (perfect
storm)
Challenges of Restoration
The system operator’s goal is to make
sure everyone is safe first, then get the
lights back on. Challenges during a
major system restoration are dealing
with the public, the media, getting the
frequency stabilized, and balancing the
generation to the load.
94
Arizona-Southern California Outages
September 8, 2011
Initiating Event:
• 500 kV line
• Due to an operating error
• A hot summer day
Outcome:
• Complete outage for San
Diego and southwest
Arizona
• Five different utilities lost
load
o million customers
• All load was restored in
about 12 hours
SDG&E 4293 MW
CFE 2150 MW
IID 929 MW
APS 389 MW
WALC 74 MW
3 | Power System Operations
95
FERC/NERC Report Findings
The system was not being operated in a secure state for an N-1 outage due to:
• Lack of information sharing between entities
• Lack of adequate studies
• Sub-100-kV facilities not adequately considered in next-day studies
Some of the NERC Standards that were violated were:
• COM-002-2, R2
o Issue directives in a clear and concise manner
o Three-part communication
• EOP-001-2.1b
o Developing, maintaining, and implementing emergency plans
• EOP-003-2
o Shed load rather than risking uncontrolled failure or cascade
• EOP-005-2
o Returning system to normal following a disturbance
• EOP-006-2
o Coordination with Reliability Coordinator
• TOP-004-2
o Operate so that instability, uncontrolled separation, or cascading outages will not occur due to the
most severe single contingency
96
Check Your Knowledge
1. What causes disturbances?
2. What are the fundamental challenges of building from a blackout?
4 | Regulation
97
4 | Regulation
Topics covered in this section are:
• Regulatory Agencies
• Evolution of the North American electric system
• Risk, Audit, and Enforcement
Public vs. Private vs.
Municipal Utilities
American Public Power
Association | 2015-2016 Annual
Directory & Statistical Report.
www.power.org
Municipals
(Muni’s)
• Utility companies that are publicly owned for
providing power to a city’s residents
• Size of muni’s vary
• Often regulated by state
PUC’s
Rural Electric
Cooperatives
(Co-ops)
• Member-owned utilities
• Rural customers over a wide area
• Generally not-for-profit
• No federal taxes,
sometimes not even state
regulated
Investor
Owned Utilites
(IOU)
• Owned by shareholders for profit
• De-regulation and market-based pricing
• Wholesale services
regulated by FERC and
Securities and Exchange
Commission
Federal Power
Agencies
• BPA, WAPA • DOE
Power
Marketers
• Buy and sell electricity at wholesale among all
electric utilities
• Generally do not own or control electricity
assets
• FERC
98
Power Cost and Rates
Unlike other commodities, electricity cannot be stored, so rates have a direct relationship to supply and
demand. Electricity prices also reflect the cost to build, finance, maintain, and operate power plants and the
electric grid. Electricity prices are influenced by:
• Energy
• Capital (building lines and generators)
• Expenses (employees, maintenance, etc.)
• Interest and return on borrowed or invested capital
• Taxes on profit
Cost
Return on Investment = Allowed rate of return
• Set by Public Utility Commission
• Cannot keep extra profits
• Can earn less than allowed rate of return
…in which case, the investors go to another investment.
…in which case, stock price goes down; harder to finance construction.
Rates
• Add up all the costs to serve a group of customers
• Divide by the number of kWh you think they will consume
• Calculate $/kWh (In Utah that is about $.10 for residential customers)
• Add charges for demand, power factor, etc.
• Use different rates for different usage levels to provide fairness and incentive for more or less usage
• Get rate structure approved
• California $0.18
• Colorado $0.12
• New York $0.17
• Utah $0.10
• Washington $0.09
• Hawaii $0.32
• Texas $0.12
• Paris $0.17
Data for 2015 | Release Date: January
2017 www.eia.gov/electricity/state/
4 | Regulation
99
Power Bill Examples
Customer with Rooftop Solar
Customer without Rooftop Solar
100
Light Bulb Cost Comparison
Bulb Type Incandescent LED
Replacement Cost $0.5 $5
Life 1,000 30,000
Energy per kWh 0.08 0.08
Wattage 100 23
Reliability Planning and Performance Analysis
Planning Services
Base cases, transmission studies, scenario planning
Reliability Assessments
Power supply assessment, state of the interconnection
Performance Analysis
Event analysis, operational practices survey
Standards Development
Regional Standards, variances, and interpretations
Entity Oversight
• Entity registration
• Inherent risk assessment
• Internal controls evaluation
4 | Regulation
101
• Auditing: critical infrastructure protection, operations and planning
• Standards violation enforcement
102
Reliability Planning and Performance Analysis
Planning Services
Base cases, transmission studies, scenario planning
Reliability Assessments
Power supply assessment, state of the interconnection
Performance Analysis
Event analysis, operational practices survey
Standards Development
Regional Standards, variances, and interpretations
Entity Oversight
• Entity registration
• Inherent risk assessment
• Internal controls evaluation
• Auditing: critical infrastructure protection, operations and planning
• Standards violation enforcement
Working Together on Standards Development
WECC Process—WECC Standards Committee (WSC)
• Standards Authorization Request (SAR)
• Drafting Team
• Vote of Members
• Board Approves
NERC Process—NERC Standards Committee (SC)
1. Standards Authorization Request (SAR)
2. Drafting Team
3. Vote of Members
4. Board Approves
5. FERC—Final Approval
4 | Regulation
103
NERC Functional Model
• Balancing Authorities (BA)
• Compliance Enforcement Authority
• Distribution Providers (DP)
• Generator Operators (GOP)
• Generator Owners (GO)
• Interchange Coordinator
• Load-Serving Entity
• Market Operator (Resource Integrator)
• Planning Coordinator (PC)
• Purchase Selling Entity
• Reliability Assurer
• Resource Planner
• Standards Developer
• Transmission Operators (TOP)
• Transmission Owners (TO)
• Transmission Planner (TP)
• Transmission Service Provider (TSP)
NERC Mandatory Standards: Subject to Enforcement
BAL Resource and Demand Balancing 10
CIP Critical Infrastructure Protection 11
COM Communications 2
EOP Emergency Preparedness and Operations 6
FAC Facilities Design, Connections, and
Maintenance
9
INT Interchange Reliability Operations and
Coordination
4
IRO Interconnection Reliability Operations
and Coordination
11
MOD Modeling, Data, and Analysis 13
NUC Nuclear 1
PER Personnel Performance, Training, and
Qualifications
3
PRC Protection and Control 20
TOP Transmission Operations 3
TPL Transmission Planning 2
VAR Voltage and Reactive 4
104
WECC-Approved Regional Standards
Other Regulating Agencies
Peak Reliability
The single Reliability Coordinator (RC) in the WECC region. Peak provides situational awareness and real-
time monitoring of the Western Interconnection.
State Public Regulatory/Service Commission
Environmental Protection Agency
US Army Corps of Engineers, Fish and Wildlife
State, County, City
Zoning, taxing, industrial facilities citing, state historical preservation office
105
Check Your Knowledge
1. What is DOE? What is its role?
2. What is FERC? What is its role?
3. What is NERC? What is its role?
4. What is WECC? What is its role?
5. How do these organizations interact?
6. How do these organizations impact the industry?
106
Risk, Audit, and Enforcement
NERC and WECC use the Compliance Monitoring and Enforcement Program (CMEP).
Delegation Agreement
• Develop standards
• Develop training
• Conduct reliability assessments and event analysis
• Regulate entities
Compliance Objective
Monitor and enforce compliance with mandatory reliability standards approved by the Federal Energy
Regulatory Commission (FERC) and by authorities in Alberta, British
Columbia, Canada, and in Baja California, Mexico.
Risk
Risk Analysis
Perform inherent risk assessments and issue
compliance oversight plans.
Internal Controls
Evaluate internal controls as a high- vs. low-
risk measure.
Investigate Noncompliance
Support enforcement on settlements and open
enforcement actions.
Compliance Monitoring
Subject matter experts in—
• Operations and Planning (O&P) Compliance
Monitoring
• Critical Infrastructure Procedures (CIP) Compliance Monitoring
Enforcement
• Research, analyze, and process Open Enforcement Action dispositions
• Conduct settlement activities (for penalties and sanctions)
107
5 | Environment and the Grid
This section includes discussion about the environment related to Generation and Transmission.
Generation
Controlled and Uncontrolled Pollution
Air Quality
• Clean Air Act
o SOx (Sulphur Dioxide)
o NOx (Nitrous Oxide)
• ROX (Dust)
• Clean Air Mercury Rule (CAMR)
o Mercury
• Ash
• Carbon Dioxide
o Competing views
Global Warming
Global Warming Potential (GWP) developed to:
• Measure across different types of gases
• Create a common unit of measure
• Measure how much energy the emissions of 1 ton of a gas will absorb over a given period relative to
the emissions of 1 ton of carbon dioxide (CO2).
The GWP—
• Allows analysts to add up emissions estimates of different gases (e.g., to compile a national GHG
inventory).
108
• Enables regulators and policymakers to compare emissions reduction opportunities across sectors and
gases.
GWP Estimates—https://www.epa.gov/ghgemissions/understanding-global-warming-potentials
IPCC’s 5th Climate Change Assessment Report
Fossil Fuel Emission Comparatives: (*lbs./Billion BTU of Energy Input)
109
Fossil Fuel Emission Comparatives: (*lbs./Megawatt Hour of Electric Energy Produced)
110
Coal
Coal = Carbon + dirt
Combustion product is
CO2 + dirt + SOx + NOx
Natural Gas
Natural Gas = CH4
Combustion product is
CO2 + 2-H2O + SOx + NOx + VOC
Renewables: Wind
111
Renewables: Solar and Thermal
Water Usage
112
View Scape
• NIMBY (Not In My Back Yard)
• BANANA (Build Absolutely Nothing Anywhere Near Anything)
• Aesthetics
• Use of Public Lands
113
Transmission
• NEPA (National Environmental Policy Act)
• NIMBY (Not In My Back Yard)
• ROW (Right-of-Way)
• Easements
• Environmental Impact Statement (EIS)
• Cultural protected sites
• Animal habitats
• People habitats
114
Overhead vs. Underground
Trends
It is all a matter of perspective.
115
6 | Current Events
Key Drivers to public-interest concerns:
• Future makeup of the Grid
• Changes in consumer and rate-payer sentiments
• Evolving technologies and regulations
• Operational and physical infrastructure upgrades
Environmental Issues: Climate Change
• Anthropogenic + natural factors
• Kyoto Protocol—1997 binding agreement—UN Framework Convention on Climate Change
• Logic: “common but differentiated responsibilities”
Paris Agreement: 133/197 countries ratified agreement to: Global temperature rise below 2 degrees Celsius.
($$$, technology, others)
Technological Changes
Drivers Changing the Resource Mix
• Market dynamics
• Aging coal and gas fleet—Upgrades expensive
• Changing economics of: prices, quantity
o Coal versus natural gas
o Fossil fuels versus Renewables
• Regulatory Policy (e.g.: CPP)
o MATS—Mercury and Air Toxics Standard
o Haze
o CPP (Clean Power Plan—stranded in courts)
116
Natural Gas Recovery
Hydraulic Fracturing
117
CPP Affected Generation
(Percentage of Business as Usual)
• Source based rule—Location matters
• Fossil-fuel-producing states
• Critical for regional
• Compliance
• On average, 11 percent reduction (28
million metric tons) is needed across the
Western Interconnection by 2024
• Emission trading encouraged
between states
Changing Resource Mix Implications
More pressure on traditional base-load
resources
• Coal plants/EPA CPP
• Nuclear retirements
• Loss of storable fuel supply
• Loss of inertia and other essential
reliability services
Expansion of Variable Energy Resources
• Behind the meter
• Utility scale solar
• Wind
• Lack of visibility
• Increasing flexibility needs
• More weather dependency
• Contribution to peak load
Natural gas transition
• Combined Cycle Gas Turbine
• Reliance on “just-in-time” delivery
• Infrastructure adequacy and security
• Unclear “firmness”
118
Clean Power Plan Realities and Limitations
• U.S. Supreme Court upheld a stay on CPP
• D.C. Circuit Court to rule anytime in 2017
• What WECC cannot do with any reliability assessments of federal/state regulations
o Entity-specific and localized studies that entities typically do
o Recommend mitigation solutions and analyses
o Use Production Cost Modeling (PCM) studies to convey any “compliance cost” estimates
Solar Price Trends
$0.00
$2.00
$4.00
$6.00
$8.00
2010 2011 2012 2013 2014 2015 2016 2017
20
17
USD
per
Wat
t D
C
Installed Costs (NREL Sunshot 2017)
Residential PV Commercial PV Fixed Tilt Utility PV
119
Solar—PV Growth
0.0
5.0
10.0
15.0
20.0
25.0
30.0
2016201520142013201220112010200920082007200620052004
Gig
awat
t D
C
US PV Market Growth (NREL Sunshot 2017)
Annual Utility-scale PV Annual Commercial PV
Annual Residential PV Cumulative Utility-scale PV
Cumulative Commercial PV Cumulative Residential PV
120
Current Events
What is challenging the electric utility industry today?
Cluster-Solar Resource Loss Incidents
• “Unknown” reliability risks
o August 16, 2016–February 6, 2017—Eight instances of inverter-based generation drop-off
o 30 MW to 1,170 MW of generation lost
• Reasons for gen loss—unclear
• South Australia experienced similar drop-off
• Some generation rides through low-fault voltage
Industry—Regulatory Community Response
• Industry aware
• Regulatory community aware
• NERC taskforce
• Increased awareness for “minimum standards-like recommendations” for inverter-based generators
121
Western Interconnection Frequency
122
Key Current Challenges
• More Renewables (solar, wind, thermal)
• Less fossil fuel usage
• Steady/low load growth
• Electric cars
• Electric storage
• Reverse distributed power
• Cybersecurity
• Climate change
• Investment recovery
123
Appendix A—Glossary
A
ACE Area Control Error. Measures whether a Balancing Authority is
meeting its scheduled import and export of power as well as
meeting its responsibility to control frequency. This helps to control
the interconnection frequency.
AGC Automatic Generation Control is a system for adjusting the power
output of generators in response to changes in the load to balance
the power system.
Alternating Current An electric current that reverses its direction many times a second at
regular intervals, typically 60 times per second in North American
power systems. Alternating Current is necessary for transformers to
change voltage from low to high voltage and back, thereby enabling
long-distance transmission of power.
Amperes (Amp or A) A measurement of electrical current equal to flow of one coulomb
per second.
AVB Attitude value behavior.
AVR Automatic Voltage Regulator. A device that works with the exciter
of a generator that can be set to control the generator’s output
voltage to a particular level.
B
BA Balancing Authority. The responsible entity that integrates resource
plans ahead of time, maintains load-interchange-generation balance
within a Balancing Authority Area, and supports interconnection
frequency in real-time.
BAL A category of Standards relating to Resources and Demand
Balancing.
BANANA Build Absolutely Nothing Anywhere Near Anything.
124
BAU Business as Usual.
C
CAMR Clean Air Mercury Rule.
Capacitance A measurement for capacitors in terms of the ratio of voltage to charge.
1) The ratio of an impressed charge on a conductor to the
corresponding change in potential. 2) The ratio of the charge on either
conductor of a capacitor to the potential difference between the
conductors.
Capacitor An electrical device having capacitance. A capacitor usually consists of
two metal plates separated by an insulating layer. In utilities,
capacitors consist of large, metal cans with insulated terminals. The
conductors of a transmission line can also act as capacitors.
CIP Critical Infrastructure Projection. A category of Standards.
Clean Power Plan (CPP) A policy aimed at reducing carbon dioxide emissions by a total of 32
percent of 2005 levels by the end of 2030. The policy was first proposed
by the Environmental Protection Agency in June 2014, under the
administration of U.S. President Barack Obama. The final version of the
plan was unveiled by President Obama on August 3, 2015.
Compliance 1) When an entity meets the requirements of a federally mandated
(NERC) standard. 2) WECC and NERC efforts to monitor and enforce
compliance with mandatory reliability standards approved by the
Federal Energy Regulatory Commission (FERC) and by authorities in
Alberta and British Columbia, Canada, and Baja California, Mexico.
Fspp Conductors 1) Wire or other devices made from elements or compounds such as
aluminum, copper, and steel that transmit electricity. 2) Wires or cable
used in transmission and distribution lines and underground cable.
Current The flow of charge in a conductor. Measured in terms of how much
charge passes a point in one second. Unit of measure is amperes or
amps.
125
Curtailment A reduction in scheduled power flow due to limitations of the
transmission system.
D
DCS Digital Control System. Typically used to monitor and control a
generating plant.
Direct Current The flow of electricity is in one direction only.
Distribution Substation An electrical facility including transformers, circuit breakers and
switches, and electrical controls that transforms higher-voltage
electricity to a distribution-level voltage (e.g., 12.47 kV), which serves
neighborhoods or commercial customers.
DP Distribution Provider. Provides and operates the “wires” between the
transmission system and the end-use customer. For those end-use
customers who are served at transmission voltages, the Transmission
Owner also serves as the Distribution Provider. Thus, the Distribution
Provider is not defined by a specific voltage, but rather as performing
the distribution function at any voltage.
E
Electromagnetism Magnetism produced by an electric current.
Electromagnetic induction A voltage created by a changing magnetic field.
Energy The product of power and time. In electricity, energy is measured in
watt-hours or more commonly kilowatt hours (kWh) delivered over
time.
Environmental Impact
Assessment (EIA)
Environmental Impact Assessment (EIA) is the process of examining
the anticipated environmental effects of a proposed project—from
consideration of environmental aspects at design stage, through
consultation and preparation of an Environmental Impact Assessment
Report (EIAR). Focus of the EIA is to assist the relevant U.S. federal
agency in determining whether a project should be permitted to
proceed, encompassing public response to that decision.
126
Environmental Impact
Statement (EIS)
Federal agencies prepare an Environmental Impact Statement (EIS) if a
proposed major federal action is determined to significantly affect the
quality of the human environment. The regulatory requirements for an
EIS are more detailed and rigorous than the requirements for an EIA.
e-Tagging The process that allows each transaction of power sales and purchases
to be uniquely identified. This process facilitates timely schedule cuts if
problems arise.
Extra-High Voltage (EHV) Transmission lines operating above 230 kV.
F
FAC A category of Standards relating to Facilities, Design Connections, and
Maintenance.
Farad (F) A unit of electrical capacitance where one coulomb of charge causes a
potential difference of one volt.
FERC
Federal Power
Commission (FPC)
Federal Energy Regulatory Commission. The United States federal
agency reporting to the U.S. Department of Energy (DOE). FERC
regulates the transmission and wholesale sale of electricity, natural
gas, and oil in interstate commerce.
*what is the FPC?
D Frequency The rate at which electric alternating current cycles from positive to
negative and back. Frequency is measured in cycles per second or
Hertz (60 Hz is used by North American utilities).
G
Generation The production of electricity by a generator.
127
Generator A device that produces electricity. Most commonly consists of a
magnetized rotor spinning inside a set of stator windings.
GOP Generator Operator. The entity that operates a generating facility
and performs the functions of supplying energy and Interconnected
Operations Services.
GWP Global Warming Potential
H
Henry The unit for quantifying the electrical inductance of a device.
High-Voltage Direct
Current (HVDC) Transmission lines with voltages ups to 1,000 kV pole to pole.
Hertz (Hz) Frequency is measured in hertz. One hertz equals one cycle per
second.
HMI Human Machine Interface. A device in a substation or powerplant
that allows users to view equipment status and control devices.
I
Inadvertent Interchange The difference between the Balancing Authority’s Net Actual
Interchange and Net Scheduled Interchange. (IA-IS). Net power
flow into or out of a Balancing Authority area that is different than
desired—due to problems such as errors in metering, scheduling,
generation, or ramp rate.
Insulator Non-conducting devices that attach the energized conductors to the
support tower. Insulation may also surround conductors in high
voltage underground cable.
Interconnection 1) Geographic area that is electrically tied together and synchronized
at a frequency of 60 Hz. In the NERC area, there are four
interconnections, including the Western Interconnection. 2) Any one
of the four major electric system networks in North America:
Eastern, Western, ERCOT, and Quebec.
IPCC Intergovernmental Panel on Climate Change
128
IRO A category of Standards relating to Interconnection Reliability
Operations and Coordination.
ISO Independent System Operator. An entity that jointly operates lines
and generators from several utilities to improve reliable and
economical service.
J
Joules A unit of measurement for energy—equal to one watt-second.
L
Load The electrical power required by connected electrical equipment.
Usually measured in watts or kilowatts.
M
MOD A category of Standards relating to Modeling, Data, and Analysis.
MSSC Most Severe Single Contingency
N
N-1 Normal minus 1 contingency. Utilities must ensure that the system
is able to maintain stability and operate within acceptable limits
following an outage by planning for N-1 (one outage) and N-2 (two
outages), etc.
NAESB North American Energy Standards Board. Serves as an industry
forum for the development and promotion of standards, which will
lead to a seamless marketplace for wholesale and retail natural gas
and electricity.
National Environmental
Policy Act (NEPA)
NEPA was signed into law on January 1, 1970. NEPA requires
federal agencies to assess the environmental effects of their
proposed actions prior to making decisions. The range of actions
covered by NEPA is broad and includes making decisions on permit
applications, adopting federal land management actions, and
constructing highways and other publicly-owned facilities. Using
the NEPA process, agencies evaluate the environmental and related
129
social and economic effects of their proposed actions. Agencies also
provide opportunities for public review and comment on those
evaluations.
NERC North American Electric Reliability Corporation. An independent
agency that promotes the reliability of the bulk power system in
North America. NERC is the Electric Reliability Organization (ERO)
commissioned by FERC.
NIMBY Not in My Back Yard.
NOX Nitrous Oxide.
O
OFAF Oil—Forced Circulation, Air—Forced Circulation. An MVA rating
applied to a transformer with cooling devices applied in this
configuration.
Ohm A unit of electrical resistance defined as the resistance of a circuit
with a voltage of one volt and a current flow of one ampere.
Ohm’s Law Defines the relationship between voltage, current and resistance and
is applicable to both AC and DC systems.
ONAF Oil—Natural Circulation, Air—Forced Circulation: An MVA rating
applied to a transformer with cooling devices applied in this
configuration.
ONAN Oil—Natural Circulation, Air—Natural Circulation. An MVA rating
applied to a transformer with cooling devices applied in this
configuration.
P
Parallel Circuit A circuit that has more than one path for current to flow.
PC (Planning
Coordinator) The responsible entity that coordinates and integrates transmission
Facilities and service plans, resource plans, and Protection Systems.
130
Peak Reliability An organization that provides situational awareness and real-time
monitoring of the Western Interconnection.
Phase Angle The angle difference between two sine waves with the same
frequency.
Power (P) Power is the rate at which work can be performed.
Power System Operations Includes both the equipment as well as economic dispatch of power.
PRC
A category of Standards relating to Protection and Control.
PSS Power System Stabilizer. A device that monitors system oscillations
and provides feedback to the generator exciter to help control
oscillations.
R
Reactive Power Power that supports magnetic and electric fields that are required by
AC systems to function. In Reactive Power, voltage and current are
90 degrees out of phase with each other.
Real Power Power that does the heating, lighting, and turning off motors, etc. In
real power, voltage and current are in-phase.
Relay A device that senses system conditions and is programmed to send
trip signals to circuit breakers if conditions require.
Reserve Sharing Group Consists of two or more Balancing Authorities that collectively
maintain, allocate, and supply operating reserves for use in
recovering from contingencies within the group.
Resistor A device in an electrical circuit that has electrical resistance. When
connected to an energized circuit, a resistor consumes real power to
create heat or light.
Right-of-Way (ROW) The land over which one or more transmission lines pass. The land
may be owned, leased, or provide certain easement rights.
131
Rotor The rotating member of an electrical machine.
S
SC Standards Committee (NERC).
Sag The vertical distance the line droops between support structures in a
transmission or distribution line. Sag is usually measured at the
span’s midpoint.
SAR Standards Authorization Request.
SCADA Supervisory Control and Data Acquisition.
Series Circuit A circuit that has only one path for current to flow.
Shield Wires Wires that protect the energized conductors from lightning strikes.
SOX Sulphur Dioxide.
Stator A stationary part in a generator that contains the field windings and
within which a rotor revolves.
Substation A facility where transmission lines terminate or connect to other
transmission lines and where transformers are used to change the
voltage from one line to another.
Switching Station Transmission substation that does not contain any transformers.
T
TO (Transmission
Operator) The entity that owns and maintains transmission facilities.
TOP (Transmission
Operations) The entity responsible for the reliability of its local transmission
system, and that operates or directs the operations of the
transmission facilities.
TPL A category of Standards relating to Transmission Planning.
132
Towers The structures that support high-voltage transmission line
conductors.
Transformer A device that changes high voltage to low voltage using magnetic
induction, enables high-voltage transmission of power, and works
only with AC power.
Transmission High-voltage electric lines that carry power over long distances.
Typically, transmission lines carry power from substation to
substation, where it may be transformed down and sent out to
customers on lower-voltage distribution lines.
Transistor Usually a smaller (thumbnail sized down to microscopic sized)
semiconductor device used to switch electricity on or off.
U
Ultra-High Voltage (UHV) Transmission lines operating above 800 kV.
Unscheduled Flow (USF) The phenomenon by which power flows over paths other than its
contracted or scheduled paths.
V
VAR Volt-amperes-reactive. See Reactive Power.
VER Variable Energy Resources.
V Curve Shows the relationship between Field Current and Armature
Current for different real and reactive power output levels of a
Generator.
Voltage (V) A measure of electrical pressure measured in volts.
Volts (V) A unit of measurement of electrical pressure.
W
133
Watt (W) The unit of measure for power being used at any given instant of
time—the product of current and voltage.
Watt hour A unit of measure for how much energy is used over time. The
power industry commonly uses kilowatt hours (kWh).
WECC (Western
Electricity Coordinating
Council)
A non-profit organization that exists to assure a reliable bulk electric
system in the Western Interconnection.
Winding A wound copper conductor. Windings are used in transformers to
produce or respond to flux in the transformer core, or to provide
inductance in a circuit.
WIRAB Western Interconnection Regional Advisory Body.
WSC WECC Standards Committee—This committee serves as a
gatekeeper for standards development activities at WECC.
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