participant guide · 1883 nikola tesla transformer/3 phase 1893 george westinghouse chicago...

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

1 | Electric Fundamentals

5


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.

https://www.youtube.com/watch?v=nd3teNgUq8E

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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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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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Why does a utility person need to know about?

• Voltage

• Current

• Power and Energy


• Circuit Components

• Circuit Analysis


41


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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


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


45

Review

1. What difference does electricity make?

2. Physics of electricity

• Voltage

• Current

• Power and energy


• Electric circuit components

• Circuit analysis

• Alternating Current

2 | How to Build an Interconnected Power System

46


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


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.


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.


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


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.)


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.


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.


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.


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.

60

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


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


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


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


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.


69

Solar-Thermal

Solar—Photo-Voltaic (PV)

Diesel Fuel Cell

70


1. What are the trade-offs between different generation types?

• Construction cost

• Fuel cost

• Renewable factors (i.e., solar, wind, etc.)

• Environment considerations


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.

3 | Power System Operations

73


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


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


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?


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


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


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

82

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


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.


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?


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.


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


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?


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


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


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


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


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)

https://www.epa.gov/ghgemissions/understanding-global-warming-potentials

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


configuration.

ONAN Oil—Natural Circulation, Air—Natural Circulation. An MVA rating


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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