Power Systems Flashcards
What factor encouraged utility companies to begin partnerships?
They wanted to become more efficient and reduce costs.
What is demand-side management?
Demand side management programs are implemented to manage load growth and achieve economic stability. They are designed to help consumers reduce their energy demand and control their energy cost while delaying the construction of generation, transmission, and distribution facilities.
Which type of generator has the fastest response capability?
simple-cycle combustion turbines
What are a power transformer’s three main purpose?
step-up system voltage
step-down system voltage
regulate system voltage during normal and emergency conditions
What are the primary features of a circuit switcher and a circuit breaker?
Circuit Switchers:
not capable of high speed closing
generally have a slower interrupting capability
Circuit Breakers:
can quickly interrupt power
capable of high speed closing
What is the primary purpose of disconnect switches?
Normally operated under no load and provide a visual break in the circuit.
Isolating devices consists of:
fuses
circuit breakers
circuit switches
Protective relays, expulsion fuses and surge arrestors operate when?
when there is an overcurrent or overvoltage
During outages or other fault conditions, electricity may become unreliable and expose equipment to potential harm. What equipment is used to ensure protective relays and circuit breakers have a reliable source of energy to operate in an emergency?
batteries
Operators rely on Contingency Analysis tools to help plan and manage the system so credible contingencies can result in acceptable performance. Contingency Analysis is:
A computer application that uses a simulated model of the power system to evaluate the effects and calculate any overloads from an outage event.
A review analysis tool that simulates and quantifies the results of problems that could occur in the power system.
A study tool for the off-line analysis of contingency events and an on-line tool to show operators the effects of future outages.
What are System Operating Limits (SOL)?
A SOL satisfies the most limiting of the prescribed operating criteria for a specified system configuration to ensure operation within acceptable reliability criteria.
Transmission owners must rate all transmission system components.
These ratings are used to establish System Operating Limits (SOL) and Interconnection Reliability Operating Limits (IROL), but these ratings are not the System Operating Limits.
Why was the North American Electric Reliability Corporation (NERC) founded?
The federal government requested the US Federal Power Commission determine the cause of the 1965 blackout and recommend ways to prevent its recurrence. One recommendation resulted in the founding of the National Electric Reliability Council, now known as the North American Electric Reliability Corporation (NERC).
In 1967, the US Federal Power Commission published a report recommending the establishment of:
“A council on power coordination made up of representatives from each of the nation’s regional coordination organizations to exchange and disseminate information on regional coordinating practices to all of the regional organizations, and to review, discuss and assist in resolving matters affection inter-regional coordination”.
The federal government launched both legislative and regulatory initiatives to promote industry competition by allowing many new entities into the electric marketplace. What was one of those initiatives?
The Energy Policy Act (EPAct) of 1992 promoted industry competition by allowing many new entities into the electric marketplace.
NERC develops and implements reliability standards in accordance with FERC-approved procedures. However, NERC does not enforce these reliability standards. Who is responsible for enforcing these procedures and standards?
Regional Entities (RE) are responsible for enforcing reliability standards NERC develops and implements in accordance with FERC-approved procedures.
Which three main function categories are defined by the NERC functional model?
The NERC functional model defines three main function categories:
standards and compliance
reliability service
planning and operation
All organizations that are officially registered as entities are subject to the compliance process, such as:
Balancing Authorities (BA) Transmission Operators (TOPs) Generating Operators (GOP) Reliability Coordinators (RC)
If a significant problem occurs in one area of the grid, and is not properly resolved, it can
affect the power supply or flow in other areas of the grid.
System operators were unable to use jet-driven auxiliary turbines to generate additional power to prevent a massive outage just before the 1977 New York City Blackout because operators for the turbines
had gone home for the evening.
The New York City Blackout of 1977 was caused by several factors including:
the Indiana Point Power plant tripping off-line
lightning strikes at the Buchanan south substation
inability to start jet-driven auxiliary generators.
The Great Northeast Blackout occurred on:
November 9th, 1965, leaving 30 million people without electricity. As the largest blackout to date, it affected the northeast portion of the US and the adjoining southeast portion of Canada, including major cities such as Toronto and New York. Although only 12 hours in duration, this blackout caused a major disruption to the lives of those affected by it.
Although November 9th, 1965 was a very cold day, investigators determined the cause of the Great Northeast Blackout of 1965 was
an incorrectly set relay near the Adam Beck Station No 2 plant in Ontario.
Although blackouts cause great inconvenience to communities, and generally result in millions of dollars of financial damage, they often provide
valuable information on how to prevent future blackouts.
Who are responsible for investigating the routine and major disturbances and events that occur within their area?
Regional Entities
Who began establishing the standards for the training and qualifications for those responsible for operation of the Bulk Electric System in 1997. Specifically, it began developing programs for System Operator Certification.
NERC
In 2002, NERC expanded its System Operator Certification Program to include specialized testing in the following areas:
- Balancing and Interchange Operator
- Transmission Operator, Balancing/Interchange and transmission Operator, and
- Reliability Operator
Some normal and emergency events that require generator units to automatically move their MW output include:
normal load changes
daily load cycling
unit startup and shutdown
disturbances such as a unit tripping
emergencies such as outages or islanding
FERC’s purpose is to:
protect the public and energy consumers
ensure energy companies act lawfully
regulate all interstate transmission of electricity and gas
Most electric generators depend on spinning turbines to generate electricity. A turbine is
a mechanical device that relies on a flowing substance such as air, water, or steam to push against its blades, shaped somewhat like the blades in your household fan. As the blades turn, they turn the central shaft they are mounted on. Mounted on the other end of the shaft are a set of magnets that turn inside a tightly wound cylinder of coiled wires. As the magnets spin, they cause the electrons in a coil of wire to move, inducing an electric current. This mechanical blade movement is converted to electrical energy which can be sent over transmission lines to locations hundreds of miles away.
All relays have a target or flag as a visual indicator the device is activated. What other valuable information do relay targets provide?
Relay targets include valuable information such as detection of an abnormal condition, what caused the problem and after-the fact analysis.
Transmission Operators must be given the authority to take timely and appropriate actions to alleviate SOL or IROL violations. These actions include which of the following?
The Transmission Operator’s actions must conform to the most limiting parameter. Actions available to the Transmission Operator may include:
redispatch
reconfiguration of the system
reduction of system load
disconnecting the affected generation of transmission facility
notifying the Reliability Coordinator and neighboring Transmission Owners
What is the purpose of the NERC Reliability Functional Model?
The NERC Reliability Functional Model:
describes the entity or group responsible for each major function
the interrelationships between the entities or groups
the communication that should occur between each entity or group
What does a power circuit breaker do?
Power circuit breakers interrupt the flow of current under normal and abnormal system conditions.
What are some causes of voltage instability.
Loss of reactive power that controls and maintains steady voltages in the system
Long transmission lines carrying high voltage during periods of light system load
High voltages due to light loading on the power system at night
The benefits of transforming power to higher voltages includes
allowing long distance transport, with fewer power line losses.
Which of the options below is NOT a type of relay?c
Which of the options below is NOT a type of relay?
Geomagnetic storms were determined to be the cause of the Quebec Blackout of 1989. Geomagnetic storms are defined as:c
Geomagnetic storms were determined to be the cause of the Quebec Blackout of 1989. Geomagnetic storms are defined as:
Who developed a system to distribute electric power in an AC format?
George Westinghouse developed a system to distribute electric power in an AC format.
Which of the following best defines the term System Operating Limits (SOL)?
A SOL is the value that satisfies the most limiting of the prescribed operating criteria for a specified system configuration to ensure operation within acceptable reliability criteria.
NERC responsibilities include:
Educate and train industry personnel
Audit owners, operators and users for preparedness
Developing and enforce reliability standards
The Power System has evolved out of the need for a reliable electric power grid that could
meet the growing demand and fluctuations of our increasing appetite for electricity.
Power =
Voltage x Current
What is a key component of power transmission and delivery that steps voltage up and down?
The step-up transformer is used to raise generated power to the high voltages used on transmission lines. The step-down transformer lowers the voltage to distribute power to the surrounding areas.
What is contingency reserve?
An amount of reserve sufficient to meet Disturbance Control Standard (DCS) criteria following the most severe contingency.
Contingency reserve is the amount of generation sufficient to meet an increase in demand, following the most severe single contingency.
When electricity is generated, there must be an equal amount of
demand for electricity on the system for stable and reliable operation of the power system.
Run-of-the-river (ROR) is a type of hydroelectric where
little or no water storage is provided.
Active power (watts) performs the work while reactive power (VAR) is
required to maintain the voltage.
In modern installations with essentially straight paths, this type of transmission line may be built with as few as six towers to a mile.
High-voltage lines
When a transmission line trips (shuts down), the loading on adjacent lines
increases instantaneously as all power previously carried by the tripped transmission line diverts to line that are operational.
Surge arresters limit
the overvoltages that may occur across transformers and other electrical equipment due to either lightning strikes or switching surges.
The opposite of the shunt capacitor is
the shunt reactor which reduces voltage under low load conditions.
What type of protection is used on capacitor banks?
Fuses
The Static VAR Compensator (SVC) is a combination of
capacitors and reactors.
SCADA is a powerful tool. How can it assist the Energy Control Center (EEC) operator?
Allows monitoring of the Interconnection
Gives control to communicate data and monitor and dispatch generation
Provide awareness of generation and outage situations
The SCADA system allows ECC Operators to be aware of generation, interchange or tie line schedules, unit maintenance schedules and outage situations. This system gives them control to communicate data, as well as monitor and dispatch generation.
SOL and IROL ratings are dependent on their ____________ under various contingencies.
stability
What are the roles and responsibilities of the Control Center Operators?
Control operators monitor the system and prepare to respond immediately to possible problems acting when necessary to avoid power disturbances as soon as any warning sign occurs.
They are responsible for dispatching field crew work activities, striving to ensure the safety when working on high voltage lines and equipment.
Due to the complexity of the electric system the control center operators must respond cautiously to avoid errors and the possible consequences an error in judgement could cause.
What are the roles and responsibilities of the Control Center Operators?
determine the cause of the blackout
recommend ways to prevent another occurrence
Responsible entities within the NERC functional model work together like players on a team to ensure
the continued and reliable operation of the BES.
The NERC functional model was created because
NERC operating policies centered on control area operations and began to lose their focus making them more difficult to apply and enforce.
Although the cause of the 2003 blackout originated in Northeast Ohio, the blackout eventually impacted
several eastern states, and parts of Ontario, Canada.
The US Federal Power Commission’s report made several recommendations following the 1965 Blackout including:
- Develop a system of controls in the electric power grid
- Ensure all emergency services have emergency backup lighting systems
- Establish the formation of the National Electric Reliability Council or NERC
Who is the official Electric Reliability Organization (ERO) for the United States?
NERC
As a government agency, FERC has the authority to implement mandatory reliability standards and levy fines for any noncompliant organization. However, FERC does not perform this task directly, but uses NERC as its official Electric Reliability Organization (ERO), to ensure all “users of the Bulk Power System” in the U. S. are compliant with reliability standards.
Who is responsible for investigating all routine and major disturbances in the Bulk Electric System that do not cross Regional Boundaries?
Regional Entities
Why do geomagnetic storms sometimes affect electricity transmission?
Geomagnetic storms often produce geomagnetic currents in the surface of the Earth, which can disrupt electricity transmission over power lines by entering grounded equipment.
Unlike previous blackouts, the events causing the 1989 Quebec Blackout took place
within a matter of seconds.
