module 3 - hydroonetraining.com systems training materials... · limits - where do they come from...
TRANSCRIPT
Slide 1
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Module 3Transmission and Distribution
www.pnxa.com Pow
erN
ex Associates
Inc.
Slide 2
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Module 3 Transmission and Distribution
Learning Objectives:
To gain an understanding of the following:
Transmission system overview (4A)ComponentsTypes of transmission limitsMajor transmission limits in Ontario
Protection Control and Metering (4B)
Concepts of Special Protection Systems (4C)
Distribution (4D)How it’s different to transmission
Slide 3
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Module 3A Transmission
Slide 4
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Module 3A Transmission
What will be covered
Basic Transmission Components
Overview of Transmission System
Limits - where do they come from & why do we need them
Internal Key Interfaces and effects on Generation
Normal, High Risk and Emergency Operation
Ontario Interconnections
Transmission Impactive Outages
Slide 5
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Basic Transmission Components
Overview of Transmission System
Limits - where do they come from & why do we need them
Internal Key Interfaces and effects on Generation
Normal, High Risk and Emergency Operation
Ontario Interconnections
Transmission Impactive Outages
Slide 6
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission The Single Line Diagram
The Single Line Diagram is a simple representation of the power system or a portion of it.
It shows the system as only one phase rather than three.
Its purpose is to show the power system with minimum detail, ie an overview of what’s connected to what.
Slide 7
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Basic Transmission Components
Single Line Diagram
Slide 8
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
SF6 Circuit Breaker
Slide 9
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Air Blast Circuit Breaker
Slide 10
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Bulk oil circuit breaker
Slide 11
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Disconnect switch
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
What happens when a disconnect switch is used instead of a circuit breaker?
Not pretty!
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
A 3 phase Transformer
Slide 14
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Power Transformer
Slide 15
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
TransmissionBasic Transmission Components
Overview of Transmission System
Limits - where do they come from & why do we need them
Internal Key Interfaces and effects on Generation
Normal, High Risk and Emergency Operation
Ontario Interconnections
Transmission Impactive Outages
Slide 16
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
TransmissionTransmission Lines in parallel, if lose one, flow is redistributed
Generally not so for Distribution lines (radial)
Parallel lines lower the impedance, the more parallel lines the higher the reliability and the lower the losses (I2R)
The higher the voltage, the greater the power carrying capacity (proportional to V squared)
Maximum power carrying ability at Surge Impedance Loading (when reactive inductance and reactive capacitance of line are equal and thus cancel each other, leaving only the resistance).
Slide 17
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
TransmissionTypical Power Grid System
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Water Flow Analogy for Electricity Transmission System
Transmission
Slide 19
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Electrical Equivalent to Water Analogy
Electrical Bus (Bucket)-Critical Voltage, Current, Frequency & Short Circuit Level
Generator (tap - water supply)-Provides Energy (MW), voltage support, &frequency support
Transmission Lines (Pipes)Impedance (Fixed Resistance to Flow)
Variable Loads (tap - water removal)Absorb MW and Voltage Support, Critical Voltage and Frequency Levels
Slide 20
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Typical Surge Impedance Loadings
500 Kv - 1,000 Mw230 Kv – 200 Mw115 Kv – 50 Mw
Ontario System made up of 500 Kv, 230 Kv, 115 Kv.
Distribution voltages < 50 Kv
Slide 21
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Double circuit EHV Transmission line
Slide 22
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Basic Transmission Components
Overview of Transmission System
Limits - where do they come from & why do we need them
Internal Key Interfaces and effects on Generation
Normal, High Risk and Emergency Operation
Ontario Interconnections
Transmission Impactive Outages
Slide 23
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Historical Note
1965 Northeast Blackout
One 230 kV circuit at Beck (Q29BD) tripped
Four other circuits at Beck cascade trip within 2.7s
1700 MW power surge into New York causing a wide-spread blackout
NPCC formed to ensure utilities in the northeastern part of North America adopt practices to prevent another blackout
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Three basic types of limits:
Thermal
Voltage Decline/ Rise
Stability
Also Short Circuit limits
Slide 26
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Lines designed to operate to specific “ground” clearance and maximum conductor temperature
Line clearance reduced as conductor temperature rises (sag)
Ground clearance decreases as
Current flow increasesAmbient temperature risesWind velocity decreasesSunlight increases
Safe Ground Clearance
TransmissionThermal Limits
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Thermal Limits – Limited Time Ratings
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Thermal Limits also apply to equipment other than lines
For example: Transformers
Rated in MVA
Require sufficient cooling to dissipate heating
Hot spot and oil temp limits
As with lines, limited time ratings
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
TransmissionVoltage Limits
Must be able to sustain Voltage levels both pre and post contingency
Low or high voltages can cause equipment damage to Hydro One or Generator assets and also customer equipment
Under normal conditions, continuous voltages are to be maintained within predefined levels.
For example:
115 Kv voltage must be between 127* Kv and 113 Kv230 Kv voltage must be between 250Kv* and 220 Kv500 Kv must be between 550 Kv and 490 Kv* In Northern Ontario 132 Kv and 260 Kv
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Voltage Limits
Transformer Voltages
Steady State Ratings, Maximum Acceptable Levels
110% of Input Winding Rating, 105% of Output Winding Rating at Full Load
Slide 31
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
Stability Limits
These are the most complex limits
Instability can cause cascading outages
Affects generators, they go out of synchronism, “pole slipping”, “out of step” are terms used.
Stability usually a problem on a system with long transmission lines
If the receiving end voltage “angle” lags the sending end voltage “angle” by 90 or more degrees, then unstable
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Stability
Slide 33
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Stability
Slide 34
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Summary of
Security
Criteria
Voltage Levels, meet customer and equipment voltage limits
Stability, acceptable damping
Element Loading, operate to appropriate thermalrating of equipment
Short Circuit, breakers have capability of clearing worst short circuit condition
Slide 35
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission “Bad Things happen”
What bad things can happen?
Virtually anything, but must be practical and reasonable.
Following 1965 Blackout NPCC developed a practical list of “bad things”
All members of NPCC must operate their systems by being able to recover from events on this list without having adverse effects on the systems of other members.
This costs money due to congestion. But the costs of a cascadingblackout far outweigh the congestion costs.
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Recognized “Bad Things” (Contingencies) - NPCC
CriteriaPermanent 3-Phase fault (worst kind of fault) – with normal fault clearing
Simultaneous permanent phase to ground faults on adjacent circuits (same tower) – with normal fault clearing
Permanent phase to ground fault on any generator, circuit, transformer or bus section - with delayed fault clearing (Breaker Failure)
Loss of any element without a fault
Permanent phase to ground fault on circuit breaker - with normal fault clearing
Failure of a circuit breaker, associated with a Special Protection Scheme, to operate
Slide 37
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission How are limits developed?
Limits are developed using computerised simulation studies.
A data base representing all of the power system components, their electrical characteristics and their connectivity has been developed and is constantly being updated when new equipment is added to the system.
This data base also includes data on interconnected systems (electrically it’s all one big system)
Application software is used by engineers to run fault simulation studies and test the operation of the system following a particular fault.
From the results of these studies operational security limits are produced.
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission How are limits developed?
Thermal LimitsFairly simple
Off line load flows predict the change in flows on remaining elements post contingency, ie distribution factors
In real time these distribution factors are used to predict change in loading on the remaining elements following a contingency
Thus the operator can determine pre-contingency loading on other lines
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission How are limits developed?
Voltage Limits
Developed by off line simulation studies
Use NPCC criteria to “throw” faults at the system
Calculate the post contingency effects on voltage
Are post contingency voltages within limits? If OK move on to next simulation. If not OK then reduce pre contingency loadings (by redispatch) in the simulation until can meet post contingency voltage criteria.
This then becomes the Operating Security Limit.
Pre-contingency loadings not to exceed these.
Slide 40
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission How are limits developed?
Stability Limits
Developed by off line simulation studies, simulating the system dynamics
Use NPCC criteria to “throw” faults at the system
Calculate the post contingency effects on stability
Is the system stable pre contingency, during the contingency and post contingency? If OK move on to next simulation. If not OK then redispatch system to reduce pre contingency loadings in the simulation until post contingency stability achieved.
This loading limit becomes the Operating Security Limit.
Pre-contingency loadings must not exceed these.
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission How are Limits Developed?
Some notes re simulation studies performed:
time consuming
only study a limited number of contingencies and system conditions (eg winter peak, summer minimum, summer peak)
study conditions set up for most severe contingency usually at peak power transfers
successful study results reduced (nominally10%) to provide acceptable margins
results simplified for easier computer monitoring
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Operating Security Limits
System needs to be secure
Pre-contingency
Post-contingency
Stable During Contingency (Transient Stability-non faulted generators not removed from system, acceptable equipment operation during/immediately after fault clearing, non cascading outages)
Slide 43
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
TransmissionBasic Transmission Components
Overview of Transmission System
Limits - where do they come from & why do we need them
Internal Key Interfaces and effects on Generation
Normal, High Risk and Emergency Operation
Ontario Interconnections
Transmission Impactive Outages
Slide 44
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Internal Ontario Key Interfaces
Because of the dynamic nature of the power system and its multiple parallel paths, limits generally are not expressed in terms of individual line loadings (other than some thermal limits)
Rather, limits are expressed in terms of interface flows and arecalled Operating Security Limits.
An interface is defined as a group of Transmission lines and thelimit is expressed as the sum of the flows on this group of lines.
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Interface Limit Characteristics
‘Base’ limit
All transmission facilities are in-service
Directional
Certain outages result in a penalty in MW
Some limits simple constants;
others more complex, and have multiple parameters including other limits!
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Historical Flows
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission Historical Flows
Slide 48
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
TransmissionBasic Transmission Components
Overview of Transmission System
Limits - where do they come from & why do we need them
Internal Key Interfaces and effects on Generation
Normal, High Risk and Emergency Operation
Ontario Interconnections
Transmission Impactive Outages
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Transmission
The End
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Module 3B Protection, Control and Metering
Slide 51
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
What will be covered
Introduction to protection,
how and why.
Introduction to control
Intoduction to metering,
revenue metering, operational metering, telemetering
Slide 52
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
All Elements of a power system must be protected from faults
All Power system elements must be monitored (status, loading, etc). Much of the power system is operated (switching, hydro unit loading) under remote control.
All generator output and all customer load must be metered(revenue grade metering)
Loading on lines, transformers etc must also be metered (non revenue grade metering)
Slide 53
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
To provide protection, control and metering, must constantly take real time measurements of system conditions
Current, voltage and frequency measurements are the basis of all protection and metering.
Current and voltage provided with the help of Instrument Transformers
Not to be confused with Power Transformers
Slide 54
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and MeteringInstrument Transformers
On a 500kv line the voltage from line to ground is ~ 290,000 volts and current can be in the hundreds of amps.
Use instrument transformers to get proportional volts and amps which can be handled by relays, meters etc
These are called Voltage Transformers (VTs) and Current Transformers (CTs).
Sometimes VTs are referred to PTs (Potential transformers), they’re synonymous
VTs are connected between the line and ground and have a turns ratio such that a secondary voltage of 120v represents rated primary voltage.
CTs are connected in series with the line and have various turns ratios that can be selected. For example 1000:5,1600:5 etc
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
Voltage Transformer
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
Instrument Transformers
Examples
On a 500 kV line
500 Kv is equivalent to 120 volts 1000 amps is equivalent to 5 amps
On a 230 Kv line
230 Kv is equivalent to 120 volts1000 amps is equivalent to 5 amps
Slide 57
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
Relays
Relays are sensing devices which operate when the monitored quantities reach certain thresholds.
They then send a signal to operate a device such as a circuit breaker
Examples later
Slide 58
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and MeteringMeters
Read monitored quantities
VoltageCurrentPower (calculated in the meter)KVA (calculated in meter)KVAR (calculated in Meter)Frequency
Display and/or store instantaneous quantities as well as integrated quantities
InstantaneousCurrentVoltageFrequency
IntegratedPower MwReactive Power Mvar
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
Slide 60
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and MeteringOperational Metering
Used forOperatingStatisticsLoading trendsAll generators, transformers, lines have this~ +/- 3 % accuracy
Revenue MeteringUsed for
Billing mainly but can also be used for above purposesPre market only included customers, interties but not generatorsNow all generators (aggregates) have revenue metersHigh accuracy ~ +/- 0.3%, expensiveExpensive because of CT and VT accuracy, especially High Voltage
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
Telemetering
To provide real time metered quantities at a central location eg IESO, OPG, HydroOneGrid Control Centre etc
Meter outputs sent to Remote Terminal Unit (RTU) and from there to central location via communication channel.
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PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
Metered data from Revenue Meters and from Operational Meters are supplied to various applications used by generators, transmitters and IESO
Confidentiality of information
Slide 63
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control and Metering
All Elements of a power system must be protectedfrom faults
Must eliminate all sources of infeed to the fault
Must be accomplished with high speed (within 2 to 3 cycles, 1 cycle = 1/60 of a second)
Must not isolate more equipment than necessary
Slide 64
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control and Metering Fault Clearing Devices
Must be capable of Interrupting fault level (short circuit concerns)
Capable of Clearing only Faulted Zone (Zone tight relaying)
Fast Acting to Protect Equipment and Limit Cascading Faults
Must Interrupt all sources of fault infeed
Slide 65
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control and Metering Fault Clearing Devices
Normally accomplished with
- combination of protective relaying scheme, 3 phase circuit breaker and high speed communication media to send trip signals to remote terminals
Slide 66
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control and Metering
Example of a transformer protection.
Differential Protection
If I1 + I2 > 0 then a trip signal is sent to the circuit breaker to remove transformer from service
Slide 67
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control and MeteringFault Clearing Device – Concerns
Fault Clearing Device Failures Mitigated by:
Breaker failure schemesDuplicated protections on all major Transmission elements (A and B protections, expensive!)Duplicate communication equipment
Slide 68
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control and Metering
Example of differential protection on a transmission line
Slide 69
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control and Metering Examples of protections on the power system
GeneratorsOverspeed (mechanical)Reverse PowerThermal Stator GroundInadvertent synchronisationOvercurrent
TransformersDifferentialOvercurrentGas accumulation
BusbarDifferentialOvercurrent
Transmission LineImpedanceDifferential
Slide 70
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control and Metering
A ground fault on the low voltage side of this substation creates an arcing fault.
Unfortunately, protection hardware fails to open the high voltage side.
Slide 71
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control and Metering
Protection panel in a relay building
Slide 72
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control
and Metering
Slide 73
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control
and Metering
IESO has no direct physical control of power system facilities (switching, unit loading etc). It only give orders!
However some switching is done automatically, such as fault switching, generation rejection, capacitor and reactor switching, transformer tap changes and such like.
But by and large all physical control of power system elements is performed by the transmitters and the generators.
Examples: synchronising and desynchronising generating units, switching at transformer stations, isolation of equipment for maintenance
Slide 74
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control
and Metering
Demarcation point between Hydro One and Generator facilities generally at the high voltage disconnect switch. Generator owns the switch.
All upstream facilities in the switchyard and beyond are owned and operated by Hydro One.
There are exceptions
Slide 75
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control
and Metering Transmitter
All control of switching on the HV system now takes place remotely from Hydro One’s Grid Control centre in Barrie.
Can remotely control all switching on 500 Kv, 230 Kvand 115 Kv systems. Controls some 44 Kv where parallel paths exist (non radial)
Controlled by SCADA system (System Control and Data Acquisition)
Slide 76
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control
and Metering Generator
Operators must be able to monitor and control equipment remotely
In staffed locations, eg Fossil stations, generator and plant control systems may be hard wired to the control room
As most hydroelectric stations are now operated remote from the site, digital control systems are normally used
Slide 77
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control
and MeteringData, metered quantities, status of equipment (open or closed) is fed from device to a Remote Terminal Unit (RTU)
From RTU data is digitised and transferred to a local Central Processing Unit (PU), basically a computer.
From there to a master CPU at the control centre where data is processed and presented to the operator on his/her screen.
This is a two way street, Operator receives data and Operator can send instructions (eg load a unit, desynchronise a unit, increase or decrease VArs etc)
Susceptible to failures, some depend on a third party communication path,
Alternative is to send agent to site to perform manual operations.
Slide 78
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control
and Metering
Slide 79
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection
Control
and Metering
Slide 80
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control
and Metering
Slide 81
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection,
Control
and MeteringAll Nuclear units controlled locally
All Fossil units controlled locally
All NW hydroelectric units controlled remotely from Thunder Bay (NWCC)
All NE hydroelectric units controlled remotely from Porcupine (NECC)
All Ottawa River and Madawaska River units controlled remotely from Chenaux
Saunders units controlled locally
All Beck and Decew units controlled from Beck
Slide 82
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Protection, Control and Metering
The End
Slide 83
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Module 3C Special Protection Systems
(SPS)
Slide 84
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Special Protection Systems
What will be covered
What they are
Why they are needed
How they work
Slide 85
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Special Protection Systems (Virtual Transmission)
Used to expand operating security limits, post contingency, therefore can operate to higher limit pre- contingency
Fast acting, are triggered by the contingency
Generation rejection (used the most)
Load rejection
Capacitor switching (provides reactive compensation to raise voltage levels and reduce phase angle between voltage and current)
can be switched automatically as part of special protection scheme
Reactor switching (provides reactive compensation to lower voltage levels and can also be used to control short circuit levels)
often used pre-contingency to lower system voltages, switched out-of-service post contingency
Slide 86
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Special Protection Systems Generation Rejection
Increase Power Transfer Capability of limiting components of Grid,
Stop Gap measure originally but continues in use
Improve Generation Resource availability
Slide 87
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Special Protection Systems
A 230 kV shunt capacitor bank
Is switched in to control low voltage and out to control high voltage
Does not necessarily have to part of an SPS, can be normal daily operation
Slide 88
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Special Protection Systems Some Generation Rejection Examples
Beauharnois/Saunders Chenaux/Mountain Chute G/R schemeStewartville G/RDarlington G/RLambton G/RLower Notch G/ROtto Holden G/R (Run Back)
Bruce Power G/R
Slide 89
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Special Protection Systems
P502X/D501P/L20D/L21S G/R & LR
NE 115 kV L/R and G/R Scheme
Abitibi Canyon G/R Scheme
Lower Notch G/R Scheme
Moose River Basin G/R for loss of ExV or XxE
Slide 90
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Special Protection Systems
The End
Slide 91
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Module #3D Distribution
Slide 92
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution Interface with Transmission System
500 kV230 Kv27.6 kV
Distribution lines
Distribution lines
Slide 93
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
DistributionInterface with the transmission system
Distribution voltages generally assumed to be < 115 kV
Various distribution voltages:
66 kV subtransmission – not common in Ontario
44 kV subtransmission – common in rural Ontario
27.6 kV subtransmission – very common in Ontario, especially in urban areas
13.8 kV
4 kV
Slide 94
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
DistributionTransmission lines are connected in parallel, if one is lost then flow is redistributed automatically
Generally not so for Distribution lines (radial), especially in rural areas.
When there is a permanent fault then switching has to occur to reroute power flow, will result in an outage (hopefully short)
Most faults (>90%) are transient and protection will open the feeder breaker, followed by an automatic reclosure. If the faultwas transient (eg caused by a lightning strike) then customer will only see a momentary flicker.
Slide 95
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution Transmission Parallel, Distribution Radial
500 kV230 Kv27.6 kV
Distribution lines
Distribution lines
Slide 96
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution Typical Hydro One interface between
Transmission and Distribution
To various customer loads
To various customer loads
27.6 kV radial distribution
feeders.
Each transformer is capable of supplying
the entire station
Normally open
Double circuit 230 kV parallel
transmission lines
Normally open
Busbar 1 Busbar 2
Slide 97
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution
Slide 98
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
DistributionDistribution equipment is less complicated
Maintenance of receiving end voltage is important; capacitor switching used extensively
Protection systems are simpler
Overcurrent, over/under voltage the main protections
Reliability of Distribution system is “local”, not a NERC or NPCC issue, does not affect the interties
Slide 99
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution
Some large industrial Customers are fed directly from 230 kV to a step down transformer.
No intermediate “subtransmission”
Slide 100
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution Structures for different voltages
500 kV 230 kV 115 kV 44 kV 13.8 kV 4 kV
Slide 101
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution
Subtransmissionand distribution lines can be on the same structure
4 kV
44 kV
Slide 102
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution
Three phase supply to a commercial facility
Slide 103
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution
LDC’s
and LSE’s
LDC – Local Distribution Company
LSE – Load Serving Entity
In NYISO LSE’s are responsible for ensuring long term supply for LDC’s in their area. This is supposed to ensure an adequate supply.
In Ontario we have the Ontario Power Authority, no LSE’s (yet)
Slide 104
PowerNex Associates Inc.Power System Operation/Electricity Market Operation Overview
Distribution
The End