NERC Prep Flashcards
Area control error
An instantaneous difference between a balancing authorities net actual and scheduled interchange , taking into account the effects of frequency bias and correction for meter error.
Contingency reserves
The provision of capacity deployed to meet the disturbance control standard and other nerc and regional reliability organization contingency requirements.
Disturbance control standard
The reliabity standard that sets the time limit following a disturbance within which a balancing authority must return its area control error to within a specified range
Operating reserve
That capability above firm system demand required to provide for regulation, load forecasting error, equipment forced and scheduled outages and local area protection. It consists of spinning and non spinning reserves
Reportable disturbance
Any event that causes an ace change greater than or equal to 80% of a balancing authorities or reserve sharing groups most severe contingency
Reserve sharing group
A group whose members consist of two or more balancing authorizes that collectively maintain allocate and supply operating reserves required for each balancing authority’s use in recovering from contingencies with the group
Disturbance
Nerc required time error to be fixed within 15 mins following a disturbance
Contingency reserves
Non spinning or supplemental and spinning reserves
Operating reserve
Non spinning , spinning reserves, and regulating reserves
Operating reserves contributors
Controllable load reserves, adjustments to interchange schedule, generation
Contingency reserve
Covers most servers single contingency , more that 80% - reportable. More than 100% of most severe contingency reportable event but no penalties apply for failure to meet DCS
Reportable contingency time
Within 15 mins recover from reportable disturbance, within 90 mins shall fully restore . 90 mins begins at end of 15 min period
Balancing authorities shall review contingencies how often to determine single worst contingency?
Annually
Contingencies occurring with in how long considered 1 event?
60 seconds
A sudden change in balancing authority’s demand supply balance following loss of generation results in sudden change in
ACE
What group can approve a change in the disturbance recovery period for an interconnection?
Nerc operating committee
Contingency reserve restoration period begins at?
The end of disturbance recovery period
Frequency bias setting
A value in mw/.1hz set into balancing authorities agc equipment to represent a balancing authorities response to a frequency deviation
Pseudo tie
A telemetered reading or value that is updated in real time and used as a tie line flow in the agc ace equation but for which no physical tie or energy metering actually exists
1% change in frequency =
2% load change in same direction - primarily of induction motors not heaters ( resistive ) this is used to determine BETA for ace equation
Generator response to governor droop
200mw/3hz x (60hz-59.95hz)=3.33mw
Frequency response charachteristic
Decrease load/decrease frequency+ generator output
Frequency bias = frequency response
x
Actual interchange + frequency bias =0 ACE
x
Bias setting
Reported to nerc yearly, must be at least 1% of the balancing authorities estimated yearly peak demand per .1hz change as described in the frequency response charachteristic survey training document for a native load serving balancing authority
Tie line frequency bias controls
Fixed frequency bias - based on a fixed straight line function of tie line deviation versus frequency deviation. Variable bias- based on a variable function of tie line deviation to frequency deviation
Balancing authorities- overlap regulation
ba that are performing overlap regulation service will increase its frequency bias setting to match the frequency response of the entire area being controlled
Balancing authorities- supplemental regulation
bA performing supplemental reg service shall not hangs its frequency bias setting
Jointly owned units
Frequnecy bias setting is included in the area in which the unit is located only
Frequency bias setting
Must be close to areas frequency response. If it is not and is set to low and an external loss of generation occurs, ace will become positive and agc will lower generation , screwing things up even more
Tie line frequency bias
Each BA shall operate its AGC on tie line frequency bias
Minimum frequency bias setting for generation only balancing authority
1% of its estimated maximum generation level in the coming year per .1 hz change
Determining fixed frequency bias
By averaging the frequency response for several disturbances during on peak hours
Dynamic schedules
When jointly owned units - each BA shall account for the unit by including their respective share of units governor response charachteristics when calculating frequency bias . Used for the value for interchange accounting purposes
Time error correction
Adjust frequency by .02 hz so if it was fast it would be 59.980 or slow is 60.020 or adjust schedule frequency bias setting to + or - 20% of bias setting and take that off of NIs so for example if area had bias setting of 100mw it would add or subtract 20 me to NIs from ace equation
AGC
Automatically adjusts a balancing authorities generation from a central location to maintain its interchange schedule plus frequency bias.. Limits change in ACE to maintain a good cOS
CPS1
Measures a balancing authorities impact on interconnection frequency
CPS2
Measures the ability of a balancing authority to manage unscheduleed flows
Regulating reserve
The part of the operating reserve used to keep ace within a reasonable value to comply with CPS standards
Flat frequency control
Only used when area is islanded includes only 10b(Fa-Fs) part of ACE equation
Ace calculated every
6 seconds
Supplemental regulation service
Is a method of providing regulation service in which the balancing authority providing regulation service recieved a signal representing all or a portion of the other balancing authorities ACE
Overlap regulation service
A method of providing regulation service in which the balancing authority providing the regulation service incorporates all of the other balancing authorities tie lines, frequency response, and schedules into its own AGC/ ACE
Factors contributing to inadvertent interchange
Frequency support , load changes with in balancing authority, generator lag, metering errors, unilateral inadvertent interchange payback, human error
NIa
Algebraic sum of all the tie lines with adjoining balancing authorities
NIs
Scheduled flow of MW with all of the adjoining balancing authorities
Beta
Contribution to interconnection frequency control based on its frequency response charachtertics
Secondary/ good inadvertent interchange
Frequency support , regulation, governor support
Unilateral payback
Inadvertent interchange accumulations paid back unilaterally to a target of non zero ace, limited to balancing authorities L10 , cannot burden interconnection
Inadvertent interchange summaries
Must include at least the previous accumulation , net accumulation for the month, and final net accumulation for both the on peak and off peak periods
Frame relay
Data transmission technique used to send digitial info quickly to many destinations from one point of origin
Information assets
Proccessed or unproccessed data using nerc net
Nerc net
WAN used for exchanging power system info over frame relayit supports intergal security network, interchange distribution calculator, and reliability coordinator information system
Alternate pathways for communication
Looping a microwave system.. Redundant paths using different equipent such as protective relaying for transmission line carriers use microwave for one set or relays and power carrier for 2nd set of relays
Balancing authority
Integrates recourse plans ahead of time. Maintains load interchange generation with in a balancing authority area and supports frequency in real time
Reliability coordinator
The highest level of authority responsible for the reliable operation of the BES
Emergency load reduction plans
Must mitigate iROL violation within 30 mins
Balancing authority experiencing emergency
Shall only used assistance of interconnections frequency bias for the time needed to implement corrective actions
Balancing authority not experiencing trouble
Shall not unilaterally adjust generation to correct frequency problem while outside balancing authority is correcting its problem- it will strain the system plus add unshschuedulrd interchange
5% reduction in voltage
Equals overall 3% reduction in inductive and resistive loads
2nd steps for balancing authority
Manually shed firm load then request reliability coordinator to declare energy emergency
Enery emergency type
1- all available recourses are in use , foresees problems, all sources curtailed2- load management procedures are in effect , designated energy difficient, public appeals, dropping load, 3- firm load is being shed , must complete report and send within 2 business days to reliability coordinator
DOE loss of load reporting
Customer load lost,efforts to reduce load, deliberate acts of sabotag, vandalism, cyber attacks initial report due within 60 mins, final done within 48hours with all Events and remedies
NERC loss of load report
Same as DoE report but includes , unusual event that occurred to bulk system
Subject to regional reliability organization apprival,Preliminary due within 24 hours, final within 60 days
Role of regional reliability organization following a report/ disturbance
Shall make a representative available for preparation and investigation of final report, track and review status of final report recommendations, this should happen twice per year to make sure reccomendations are being acted upon, if any recommendation has not been acted on within 2 years, RRI shall notify Nercplanning committee. -SOS-notes/#sthash.11jXj9fk.dpuf
Transmission operators responsible for
Reliability of local transmission system, operates or directs operations of the transmission facilities, provides maintainence schedules, maintains voltage profiles , defines operating limits, develops contingency plans, coordinates load shedding
87 relay
Differential relay
21 relay
Distance relay
67 relay
Directional over current relay
Transfer trip signal
Form of pilot relaying, can be sent over fiber optics, microwave etc
Distance relays
3 zones of protection
System operating limits based on
Facility ratings, transient stability ratings, voltage stability ratings , system voltage limits
Voltage collapse
Lack of reactive power, voltage down by 10-20%, not enough mvars to serve power system and loads
Getting ahead of voltage
Putting capacitor banks in service before planned outage
Other actions to get ahead of voltage
Take shunt reactors out of service, raise generator voltage,raise tap positions on transformers, return lines and generators to service, curtail interchange transactions, curtail or shed load
Prevent voltage collapse by
Carrying dynamic reactive reserves close to the load, if mvars are not available shed load, ideally heavy inductive loads
Instability
Trans system does not have reserve transmission capacity mw or mvar reserves to handle the loss of a major electrical component such as line or generator
Uncontrolled separation
Instability when the power angle between two sections grows to large and the magnetic bond between the two sections is not sufficient to keep generators from losing sychronism
N-1
Operating the system to satisfy the most severe single contingency is also referred to as operating to satisfy the most severe N-1
TOs operate to protect against
Instability, uncontrolled separation, cascading outages from multiple outages
SOL
Must return system to within normal operating limits within 30 mins, transmission operator must take immediate action such as curtailing loads, energy service etc
Operational reliability info that balancing authorities provide reliability coordinators with
To be updated every 10 mins.. Example tie lines flows, operating reserves, mw reserve available within 10 minutes
Power angle
Difference in voltage angles between two locations in the power system
More capacitive circuit
Current will lead voltage which will tend to raise voltage
As power angle increases power transfer increases
x
Torque angle
Difference in voltage angles between generator internal or excitation voltage and the system voltage
Real power flows from
Higher voltage angle to lower voltage angle
Real power transfer
The higher the voltage the lower the power angle required for a given power transfer
When iROL or sol exceeded for more than 30 mins
Notify nerc and rro
Transformers rated in?
MVA
Shunt capacitor banks
Supply reactive power to the inductive load, reduce current between generator and load, reduce mvar losses
Shunt reactors
Absorb excessive reactive power locally
Capacitor
Element that stores energy in the form of electrical charge and introduces capacitance into a circuit . The stored energy creates an electrical field
Capacitive reactance
Measure of how a capacitor affects the flow of ac current . It describes the reaction of a circuit to the fluctuating electric fields of ac voltage. A capacitor that is places into an ac circuit builds up a charge that opposes change in voltage
Inductance
The property of an electrical circuit that produxes an electromotive force by induction when the current is changing. Inductance opposes current changes
Reactive power
The product of voltage and out of phase current , measured in volt ampheres reactive or var.
MVA
Consists of 2 different types of power, megawatts and mvar, mw does the actual work or real power… Mvar produces the magnetic field that enables the power to do the work
Angular separation or phase angle
Angular seperatipn between current and voltage cycles..in capacitive circuit. Current leads voltage . Inductive circuit is opposite
How to raise voltage on a system
Capacitive reactance must me increased or inductive reactance lowered
Placing capacitor near inductive load
Reduces current flow and line losses
Dynamic sources of reactive power
Transmission lines and generators w auto voltage regulators
Knee of pv curve
Once this point is reached . Any increase in mw will cause voltage collapse , to avoid this , redid patch generation or place capacitors inservce closer to the load
Ace DCS violation restore time
15 minutes
If a transmission operator is in unknown state
He has 30 minutes to restore
AGC control types
Pulse control or set point contro
Agc pulse contro
Units recieve raise or lower controls every few seconds this pulse acts on a speed changer motor to change its load reference settings in small increments
Set point control for agc
Set desired mega watts fed directly to turbine controls- once through fossil units use this
Communications
Must be redundant such as looping a microwave system or using redundant paths with different equipment
Facilities management
All operators who may need to use backup system should practice with it monthly ,
Communications
Coordinated communications include nerc hotline, weccnet, and reliability coordinator information system .. Must have procedures for backup communications
Nerc net
A WAN that supports interregional security network, interchange distribution calculator and the reliability coordinator information system
Communications and coordination
Each TO and BA shall notify its RC and all other potentially affected TO and BA through pre determined communication paths of any condition that could impact reliability or which could require firm load shedding
Voltage reduction customer demand
A 5% reduction in voltage will drop load by 3%
Emergency operating agreements between adjacent BAs
- Provisions for emergency assistance 2. Provisions to obtain emergency assistance from remote BAs
If a BA loses its largest generating source
A neighboring BA can change the NIs part of its ace equation to make up for the generation
Reserve sharing group
Agreements for emergency assistance minimize the amount of time a bA has to rely on the interconnection for bias support - should only be used to evaluate options and resolve emergencyreturning ACE to normal values as soon as possible is primary objective
Transmission operators emergency load reduction plan
Shall have load reduction plan for all IROL that includes facilities in its area. Shall include details of amount of load shedding to be done to mitigate iROL violation before system separation or collapse occurs. Must be done within 30 minutes .
Each TO and BA shall develop 4 plans
1.’mitigateoperating emergencies for insufficient generating capacity. 2) mitigate operating emergencies on the transmission system 3) implementation of load shedding when nessasary 4) system restoration
TO and BA emergency plans to mitigate operating emergencies
1)communications protocols to be used during emergencies , including assignments to communicate within and external to the organization 2)a list of controlling actions such as starting offline generators etc 3) tasks to be coordinated with other entities such as providing reActive power, voltage control at interconnection 4) staffing levels for emergency. It is important to note that one of the controlling actions shall be load reduction in sufficient quantities to resolve emergency within established nerc guidelines
TO and BA emergency plan review
To be done once a year
BA anticipating operating emergency
Bring on all avail generation, postpone equipment maintainence , schedule interchange purchases in advance, be prepared to she’d firm load
BA not experiencing emergency
Shall not unilaterally adjust frequency during emergency. Will cause overloading of transmission lines and will develop excessive inadvertent interchange accumulation
If a BA needs to declare energy emergency
This is done through its RC
BA not complying with DCS or CPS
Shall remedy by , loading all available generation , deploying all available operating reserve, interrupting interrupt able loads and exports, requesting emergency assistance through other BAs , declaring an energy emergency though its RC , reducing load through such procedures as voltage reduction, publicappealsand curtailment of interrupt able and firm loads
Energy emergency alert levels
Eea1) when a BA or lse foresees a problem sustaining its load eea2) when a BA is no longer able to provide its customers energy requirements , eea3 when firm load shedding is imminent or in progress
CMD
Load shedding plans
Shall be coordinated with interconnected BAs and TOs to shed load for under frequency and under voltage . Load shed should be done before generation is shed. Under voltage load shedding occurs in pre selected blocks
A BA or TO or LSE experiencing a disturbance
Shall submit a preliminary written report within 24 hours to RRO and NERC and DOE of the disturbance .. If weather does not permit the writing of the report then they should verbally notify the rro and nerc
DOE reporting
Initial reporting done within60 mins ,final report done within 48 hours
DOE disturbances
Uncontrolled loss of 300mw for more than 15 mins from single incident, load shedding of 100mw during emergency plan, voltage reductions of 3% or more,public appeals to reduce use of electricity, actual or suspected attacks , fuel supply emergencies, loss of electric service to 50k customers for more than am hour, complete operational shutdown of transmission or electrical system
Nerc disturbance reporting
Loss of component that affects integrity of the interconnection, interconnection islanding, loss of generation (200mw or more in eastern and 1k I’m ercot), equipment failures that result In firm load loss for 15 mins or more, firm load shedding of 100mw or more to maintain continuity of BES,a violation of IROL , any disturbance that the operating committee wants to submit to the dawg
Final report due to nerc
Within 60 days
RRO responsibilities during emergency
Make representatives of the nerc operating committee and the dawg available to assist in final report. Track and review status pf reccomendations of report. This should occur at least twice that year
TO restoration plan requirements
Personel identified, reliable black start units, contingency plans, synchronizing areas, load restoration including critical loads , procedures for simulating and where practical testing every 3 years, training records showing restoration excersizes, functions to be coordinated with and among RC and neighbors , notifications to operating entities as steps are completed
TOP system restoration plans must be
Updated as nessasary to reflect changes and correct deficiencies , reviewed annually, developed w intent to restore interconnection , coordinated w neighboring systems , periodically testing of telecommunications equipent
TOP emergency plans as it relates to generation
Emergency power should be available to shutdown safely, operate turning gears, minimize damage to units, maintain communications , expedite restart
TO and BA must coordinate restoration actions with
RC
How to proceed after islanding or collapse
Determine extent and condition of area, contact other BAs and TOs to determine circumstances in their areas, start taking nessasary actions to restore system frequency by matching generation to load, begin reviewing interchange schedules , reschyronoze the isolated area to surrounding areas only after RC gives their approval, use strongest transmission lines and restore offsite power to nuclear station ASAP
Open circuit breakers
On distribution side of blacked out area to control power levels, also disable automatic reclosing relays.
Reschyronize with interconnection
Only done at power plant w scope, the phase angle should be less than 10 degrees, frequency should be the same and voltage magnitude close too. If differences are to large, operator can re dispatch generation to reduce differences
Self certification
Every year each TO shall self certify to the RRO compliance standard . Shall include : operating instructions for restoring loads , set of procedures for annual review and of possible simulation , documentation of personnel training records to verify training , reporting of any significant changes to restoration plan to the RRO
RC has highest level of authority
It is responsible for the coordination of system restoration
During restoration RC shall
Establish communications with other RCs the RRO and Nerc via the nerc hotline and the RC’S
Each RC is required to sign nerc standards of conduct
Nerc standards of conduct address …independence , emergency actions, reporting deviations, rules governing employee conduct, books and records,rules governing maintainence of written procedures
During restoration
Nominal voltages shall be maintained between 90-110%
Shunt capacitor banks during restoration
Should be taken out of service while restoring the system
Static var compensators and synchronous condensers during restoration
Should be placed in service as soon as practical
Synchronizing of islands
Shall be approved, coordinated, communicated by the RC as to not burden surrounding areas.
Back up control centers
Reliability entities are not required to have back up control centers but procedures must be in place if primary control center goes down. Must not burden interconnection
Loss of control center contingency plans
Must address .. Ability for instantaneous tie line mw and mvar telemetry.. Ability for instantaneous generating unit telemetry.. Ability to read mw hour accumulators for all tie lines and generating units.. Ability to collect system frequency and time error measurements.. Data links to send generation control signals to generator control centers.. Lost of critical facilities of applicable entities
Loss of control center cont.
Must contain procedures for maintaining basic voice communications .. Conduction of annual testing of plan.. Annual training. Review of plan annually.. And updating plan annually
Indications of lightening fault
Ground relay operation ( relay 64) or directional current relay (67)
Phase to phase fault
Protected by distance relay (21)
2 different types of zones for relaying
Open and closed .. Differential protection is example of closed zone.. Distance relay example of open zone
Differential relaying
Closed protective zone.. Measures current entering and leaving zone
Distance relaying
Open zone… Looks at impudence of line for a specific distance..have quality known as Reach. This tells how far down the line it will detect a fault. If it is set to high it will detect faults to far down line which will cause excess tripping
Over current relaying
Used as a backup to distance relaying and differential relaying . Can be directional or non directional ( will only trip of current is flowing 1 way) -
Pilot relaying
Protective relaying where relays communicate with each other to allow for faster and more accurate clearing of faults within line segment
Transfer trip relaying
Form of pilot relaying.. Initiated at one location and sent via communications channel to trip another breaker or trip auxiliary relay which will trip multiple circuits
Misoperation procedures
Each GO TO or anyone that owns a transmission protection system shall provide its RROwith it’s misoperation analysis and corrective action according to RRo procedures
Operating emergencies
Line overloading .. Loss of transmission line..loss of generation..shortage of reactive power
Actions TO takes during energy emergency
Curtailing transmission service.. Curtailing energy schedules. Operating equipment such as reactive sources.. Shedding firm load
A system with a generating deficiency
Must reduce its load to restore ace to an acceptable value if they cannot balance generation and load in a timely manner
Being prepared for a large system disturbance or pending voltage collapse
Areas must have a program in place to arrest these conditions..should address levels of voltage and frequency at which manual action should be taken.. Also to prevent abnormalities such as over voltage or generation instability caused by automatic load shedding
All BAs are required by nerc
To maintain operating reserves
Exceptions for burdening neighboring systems
Generator outages- must coordinate with TP…transmission facilities- must coordinate with RC
Elevating transmission service priority of an interchange transaction
You can change the priorities of interchange transactions and interrupt power if it will help the energy deficient area the LSE must have RC declare an EEA which must be posted on NERC website and include the expected level of the transmission service priority declaration
Daily load forecast is determined by tools such as
Load forecast..unit commitment.. Power flow simulation programs
SOLs are based on
Facility ratings ..transient stability ratings.. Voltage stability ratings.. System voltage limits
Economic dispatch
Point where all generation is operating at the same incremental cost while serving the demand
Transfer capability studies
Should be done between operating entities annually or whenever a change in facilities warrants a new study. All entities should use uniform line identifiers to not get confused
Transfer capability issues include
Voltage limits.. Reactive limits.. Thermal limits .. Stability limits
GO must provide info on outages for the following day
To TO for any generator greater than 50mw.. TO must provide info daily to RC if generator over 50mw or line over 100kv.. Outage info posted by 1200 cst
N-1 contingency
single worst contingency on the system
Voltage control equipment outages
Shall be coordinated between entities for AVRs..shunt capacitors etc
Voltage collapse
When there is lack of reactive power .. Voltage levels down 10-20%
Getting ahead of voltage
When you Know you are going to have a voltage decline. Place capacitors in service, take reactors out.. Raise gen voltage.. Raise transformer tap positions .. Curtail transactions.. Curtail or shed load.
When reactive recourses are limited
Limit mw transfers - this prevents power angle increases.. Keep voltage high- this reduces current and angle.. Redid patch generation .. Shift generation patterns to unload heavy loaded lines .. Request neighbor reactive support . Shed load
RC is responsible for
Scheduling of potential reliability conflicts
Uncontrolled separation can occur as the result of
When power angle gets too large between two sections and the magnetic bond breaks and they loose synchronisim
TOs must operate in anticipation of worst contingency
This night be loss of largest unit or large interchange purchase
Following a contingency or other event which results in SOL violation
TO must return limits within 30 mins.they must make every effort to stay connected to interconnection but of they deem they are in danger of sol or iROL they can disconnect
If TO enters unknown operating status
Must restore system to proven reliable operating status within 30 mins
TOs must coordinate with other TOs
Maintain develop and implement procedures to provide for transmission reliability
Transmission line capacity is determined by
Thermal limits
Transmission line inductive reactance
Dependent upon spacing between strands within each conductor and distance between each conductor
Transmission line capacitive reactance
Dependent upon size and spacing of conductors
All transmission equipment rated by
Transmission owner..these ratings are used to establish SOLs for system
TOs and BAs provide monitoring data to RC
This helps RC to perform reliability assessments .. Coordinate reliable operations within RCa and with other RCs
Electric system reliability data is updated
Every 10 mins.. Includes tie line flows generator mw output.. Etc
Torque angle
Angular difference between the rotor magnetic field and the magnetic field of the stator of the generator
Power angle
The voltage angle difference between 2 locations in the power system
Phase angle
The angular separation or difference in phase between the current and the voltage waves
RCs publish BA data and system operating assesnements
On the nerc isn or rcis.. BAs provide electric systems reliability data to the RCs via the rcis
RC,BA,TO
Shall have access to all info nessasary to balance generation and load including .. Status of generators and transmission recourses.. Protective relay status.. Weather forecast and past loads.. System frequency
Sufficient metering and monitoring equipment
Shall be provided to all RC TO and RC
3 types of stability
Steady state- no significant changes … Transient- a sudden large change….. Oscillating - constantly changing voltage frequency and angles
Avoid excessive transmission line loading
This results in large power angles.
The more transmission lines that are in service
The more power can be transferred at a given torque angle
Verify generator voltage regulators are in service
If they are in automatic the higher the voltage the lower the power angle that is required for given power transfer
Records must be kept to show
Evidence that TOinformed RC when iROL or sol was exceeded.. There were actions to return system to within limits .. The TO returned system to within an IROL -
Each iROL or sol exceeding 30 min
Shall be reported to the RRO and nerc within 72 hours.. Using nerc iROL report
Transformers are rated in
MVA..usually have several ratings associated with the stages of cooling
Shunt reactor banks
Absorb excess reactive power , usually lightly loaded lines
Priority to alleviate violations
Redispatch generation.. Curtain interchange transactions.. Disconnect overloaded equipment.. Shed load
Circuit breakers
Usually not limiting component in power transfers due to high continuous rating.. If a CB fault clearing time is too great it can limit power transfers by need for creating stability limit
Disconnect switches
Not used to interrupt fault current
Air break switches
Limited ability to interrupt load . Limited to small current ineruption such as transformer charging current
Shunt capacitor banks
When energized. Produce reactive power.
Interchange transactions and schedules may contribute to sol and iROL
Because of parallel flows
Increased current cause
Increased loading and larger power angles
When TO takes action to alleviate sol or iROL
Must notify RC and effected TOs.. If possible notify before you take action
Priority to alleviate violations
Redispatch .. Curtail interchange .. Disconnect overloaded equip.. Shed load
Benefits of being connected to interconnection
System inertia from stored energy in rotating generators.. Ability of affected system to resist changes in frequency .. Access to reserves, not only mw but also dynamic reactive reserves.. Instant assistance from tie line bias
Synchronizing relays
Need 20 percent power angle or less to tie busses together
Collapse
Low frequency .. Low voltage.. High currents
Apparent power MVA
Consists of both active and reactive power
Increased loading causes
Circuits to be more inductive
Voltage control is
Control or reactive power flow
When generator AVR is in service
It is considered a dynamic source of reactive power
Nerc standard for maintaining reactive reserves
Each TO shall have adequate reactive resources within its area to protect voltage levels under normal and contingency conditions
A strong bus
One that has 1 or more generators attached at the closed end of a line that has the ability to absord mvar
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Responsibility of development of emergency load reduction plan to respond to iROL
Transmission operator.. Plan must be able to be implemented within 30 mins
An emegency Alert is a
Emergency procedure
Nerc has how many emergency alert levels
3
Rro final reports are due within
60 days
A reportable incident shall be reported to
Nerc and rro
Doe reports are aimed at
Customer load loss, sabotage, and efforts to reduce load
Rescynchronising of major system islands should only be attempted after approval by the
Reliability coordinator
Audit of loss of primary control center plan is conducted
Every 3 years
Loss of primary control center plan must be implemented within
1 hour
Distribution providers and load serving entities take reliability directives from
Transmission operator
Balancing authority is required to maintain
Operating reserves
Angle instability
Is the inability for system to maintain magnetic bonds
