Disclaimer
• This training presentation is provided as a reference for
preparing for the PJM Certification Exam.
• Note that the following information may not reflect
current PJM rules and operating procedures.
• For current training material, please visit:
http://pjm.com/training/training-material.aspx
PJM©2014
Transmission System Operations
TO1
Interconnection Training Program
PJM State & Member Training Dept.
www.pjm.com
PJM
PJM©2011
©2011
1
Agenda
• 6 modules
–
–
–
–
–
–
www.pjm.com
Basic Theory
Reliability, Limits, Failures
Contingency Analysis
Out of Merit Dispatch
Voltage and Voltage Adjustment
Outage Scheduling
PJM©2011
2
Agenda
• Methods of Instruction
–
–
–
–
–
–
–
–
Presentation
Class discussion
Exercises
Operator Training Simulator Demonstrations
EPRI OTS PC Simulation
PowerWorld Simulator Demonstrations
Videos?
Quizzes
• 3 quizzes
www.pjm.com
PJM©2011
3
Agenda
• Purpose and Function of the Transmission System
– TO1-1
• System Voltage and VAR Characteristics
– TO1-2
• Distribution and Generation Shift Factors
– TO1-3
www.pjm.com
PJM©2011
4
Module Objectives
• Review the purpose and function of the transmission
system.
• Review basic system voltage and VAR characteristics
• Demonstrate basic distribution factor theory.
• Determine power flows utilizing system distribution
factors and generation shift factors
• Introduce the concept of $/MW effect.
www.pjm.com
PJM©2011
5
Transmission System Fundamentals
TO1-1
www.pjm.com
PJM©2011
6
Module Objectives
• List the purpose and functions of the transmission
system.
• Distinguish between the transmission system, the
sub-transmission system and the distribution system.
• Given a simple one-line diagram, identify the major
features of the PJM transmission system including:
– Lines, buses, and generating stations
www.pjm.com
PJM©2011
7
Purpose and Function of the Transmission System
• Coordinated Operation
– Single system
– Part of the Eastern Interconnection
• Reliability
• Economy
– No transmission = Distributed Generation
• $$$$
www.pjm.com
PJM©2011
8
Cabot
4
Susquehanna
PJM West PJM
2
2
6
N
524
Sunbury
5002
2
SUN N
SQ2 N
SUN S
SQ2 S
WES N
5
5045
2
to Ramapo
1
1
1
WES S
S
513
21
5043
5001
5046
3
138kV
South Bend
Keystone
513
1
1
2
2
3
14
1-6
4A
5004
CON
KEY
SUN N
CON
-TMI
KEYALB
SUN S
TMI
ALB
1
W
E
WES W
532
1
2
4
5
3
1
6
2-3
8
9
1
BE
JUNHOS
HOS
Alburtis
5027
5019
TMI
4
7
Deans
1
500802
502602
070802
502612
N
1
ELN
2
4
1
Yukon
1TRHS
1-3
1
1
1
3
500702
475
2
ELS
2-3
S
Steel City
1
2-5
2-7
5029
4
6
3
518
542
3
6
9
2
5
8
1
4
7
165
MW
165
MW
335
MW
CT1
CT2
CT3
ST1
2
Peach Bottom
5007
Conastone
2
1
Spring 2002
3
Jan 2003
N
Limerick
5010
S
N
25
15
235
205
115
125
Fall 2001
2
Jan 2003
501382
8
1
H
J
35
65
5012
575
675
1
2
3
185
285
385
1-5
1-7
2
215
225
3
1
C
#1 bank
832/985 MVA
55
245
225
4B
2
45
225
2
315
325
335
3
1-9
3
5-6
7-8
2-6
2-8
4
2-5
2
345
C182
145 MVAR
355
5024
5011
516
PJM West PJM
5023
1
3
7
1
A
Fayette
1
Keeney
Bedington
3
2
3
502
765/500 kV
3
1
1
9
7AB
8
3
2
9
2
4
2
5
5AB
501
503
2
Black Oak
1
7BB
2
2
7
3
3
8
2
6BB
2-8
2-6
9-10
1-8
5-6
5037
505
5BB
5015
504
1
2
2-6
501
50
Brighton
2-10
1-3
5-6
5036
3-4
B
508
1
1-5
502
5055
544
502
50
503
5014
3
7
Fort Martin
Red Lion
51
6AB
2
2
1
2
475
4A
L
M
B1-92
Hunterstown
Conemaugh
3
4
1
135
Hatfield
530
East Windsor
New Freedom
1
A
5013
7
1
Pleasants
200
Whitpain
5030
Jan 2003
K
5
6
to Kammer
(AEP)
5031
5006
4
2
165
MW
2
1
2
1
5021
1
5005
51
505
1
1-9
2
Hope Creek
5053
Salem
520
3
2
Doubs
1
1
2
3
4
3
2
4
1
3
4
Chalk Point
2
Calvert Cliffs
Waugh Chapel
N
3
5
6
10
7
4
1
11
8
5
2
572
BLACK
580
3
530
5052
6
3
5
54
51
55
53
50
52
11A
7
9
10
12
6
4
5
512
3
2
Meadow Brook
6
526
62
56
A
59
B
Burches
Hill
12B
11B
12C
11C
10B
6
23
to Mountianeer
5
10C
Harrison
Pruntytown
B
A
1
2
21
41
61
2
5051
765/500 kV
Belmont
G
63
RED
5
H
5071
514
510
S
12
2
43
1
5070
1
22
2
528
5072
to Mt. Storm
to Mt. Storm
to Morrisville
to Mt. Storm
to Loudoun
to Possum Point
PJM & PJM West 500 kV Breaker Diagram
KEY
transfomer
generator
breaker
capacitor
765 kV
Date
Description
Layout
11/13/2002
Layout of APS system with PJM
E.D. Colodonato
Checked
500 kV
New Construction
Created in Visio. All revisions should be made in Visio then copied to PPT
www.pjm.com
PJM©2011
1-5
1
3
2
T1
Smithburg
2
Elroy
Hosensack
Wylie Ridge
3
5020
145
5
1-7
2
175
5028
ALS
8
4
1-5
138 kV
5003
2
S
4-5
5017
5026
5008
5
Branchburg
5-6
2
4
5001
530
N
BW
3-4
JUN
4B
3
1-2
5016
WES E
5009
S
507
5018
5044
N
16
2
Wescosville
Juniata
Visio : DOC#146099
Power Point : DOC#191687
9
www.pjm.com
PJM©2011
10
www.pjm.com
PJM©2011
11
http://www.pjm.com/documents/maps.html
www.pjm.com
PJM©2011
12
Transmission Paths (Bulk Transmission)
• Purpose
– Transfer bulk power from a generation source to load
centers reliably and economically
• Typical Path lengths
– Range from 1/2 mile to 180 miles in Eastern U.S.
• PJM longest Dumont-Marysville 765 kv (AEP) 180 miles
• PJM shortest 5037 Hope Creek - Salem <1 Mile
– Longer in Western U.S.
– For EHV, longer path lengths is more economical
www.pjm.com
PJM©2011
13
Transmission Paths (Bulk Transmission)
• Typical voltage values
– Transmission is generally characterized by high voltage
values
• 69 kV - lowest voltage considered transmission
• 765 kV - Highest voltage level used in U.S.
– Different definitions depending on company
– Above 230 Kv considered EHV
www.pjm.com
PJM©2011
14
Bulk Electric System (BES)

ReliabilityFirst Corporation (RFC) adopted the
definition of Bulk Electric System (BES) to include
facilities 100kV and above

The new BES definition new includes facilities that
used to be controlled by Member TOs

All NERC and Regional standards will apply to all BES
facilities
www.pjm.com
PJM©2011
15
Bulk Electric System (BES)
The Bulk Electric System (BES) within the ReliabilityFirst
footprint is defined as all:*

Individual generation resources larger than 20 MVA or a generation plan with
aggregate capacity greater than 75 MVA that is connected via a step-up
transformer(s) to facilities operated at voltages 100 kV or higher

Lines operated at voltages 100 kV or higher

Transformers (other than generator step-up) with both primary and secondary
windings of 100 kV or higher

Associated auxiliary and protection and control system equipment that could
automatically trip a BES facility, independent of the protection and control
equipment’s voltage level
www.pjm.com
PJM©2011
16
Transmission Paths (Bulk Transmission)
Voltage
Transmission
Subtransmission
Distribution
Primary
Secondary
765 kV
500 kV
345 kV
230 kV
138 kV
115 kV
69 kV
34.5 kV
25 kV
14.4 kV
13.2 kV
12 kV
4 kV
480 V
120 V
Typical Voltage Values
www.pjm.com
PJM©2011
17
Transmission Paths (Bulk Transmission)
• Applications
– Backbone of the system
• ties generation to load
– Used to connect companies
– Used to connect to outside pools
– Generally controlled by ISO (Independent System
Operator)
• Let’s look at common flows on the transmission
system on the PC simulator!
–
www.pjm.com
H:\CorporateServices\Training\Powerworldcases\ExampleCases\ECAR\98FFECAR.pwb
PJM©2011
18
Transmission Paths (Sub-transmission)
• General definition
– Medium voltage power transmission path underlying the
bulk transmission system
• Typical voltage values
– 34.5 kV to 138 kV
• Typical path lengths
– 0.1 to 40 miles
www.pjm.com
PJM©2011
19
Transmission Paths (Sub-transmission)
• Application
– Intra-company power flow paths
– Move power from one area of a company to another
– Serve larger loads
www.pjm.com
PJM©2011
20
Transmission Paths (Distribution System)
• General definition
– Those power lines which supply energy to residential and
commercial customers and some of the smaller industrials
• Two Typical Voltage Ranges
– Primary Distribution
• 12 kV - 25 kV
– Secondary Distribution
• 120 V - 480 V
www.pjm.com
PJM©2011
21
Transmission Paths (Distribution System)
• Two types of distribution systems
– Networks
• Normally densely populated areas
– Radial
• Normally in rural areas
• Typical path lengths
– Several pole spans to many miles
• Applications
– Supply of power to customers
www.pjm.com
PJM©2011
22
Transmission Line Standards - Glossary
• ACSR
– aluminum conductor steel reinforced; Bare aluminum conductors stranded
around an inner core of galvanized steel wire(s). Often used in overhead
power distribution and transmission lines.
• Kcmil
– a measure of conductor area in thousands of circular mills; a circular mil (Cmil)
is the area of a circle with a diameter of one-thousandth (0.001) of an inch.
• kV
– kilovolt (1,000 volts)
• M
– million $
• MVA
– megavolt-ampere (1 million volt-amperes); a unit of apparent power in an
alternating-current circuit. A volt-ampere (VA) is the product of voltage (volts)
times current (amperes). A device rated at 10 amps and 120 V has a VA rating
of 1200 or 1.2 kVA or 0.0012 MVA.
www.pjm.com
PJM©2011
23
Overhead Transmission Line Standards
Overhead Lines
Voltage
Conductor Size (kcmil)
Right of Way Width
Range
Typical Normal Rating
(MVA)
Order of Magnitude
Installation Cost per
Circuit Mile (Millions)
69 kV
556 ACSR
60 - 90 ft.
85
$ 0.300 / mile
115 kV
795 ACSR
90 - 130 ft.
175
$ 0.450 / mile
138 kV
1033 ACSR
100 - 150 ft.
250
$ 0.700 / mile
230 kV
1590 ACSR
100 - 160 ft.
650
$ 0.950 / mile
345 kV
2167 ACSR
140 - 160 ft.
1650
$ 1.5 / mile
500 kV
2493 ACSR
160 - 200 ft.
2700
$ 1.8 / mile
765 kV
1351 ACSR (4 conductor
bundled)
200-250 ft.
4000
$ 2.5 / mile
www.pjm.com
PJM©2011
24
69 kV Line
 Conductor Size
 556 ACSR
 Right of Way
 60 – 90 ft.
 Normal MVA Rating
 85 MVA
 Cost per Circuit Mile
 $ 0.300 M / mile
 Structure Type
 Single Pole, Steel or Wood
www.pjm.com
PJM©2011
25
Double Circuit 115 kV Lines
 Conductor Size
 795 ACSR
 Right of Way
 90 – 130 ft.
 Normal MVA Rating
 175 MVA
 Cost per Circuit Mile
 $ 0.450 M / mile
 Structure Type
 Single Pole, Steel or Wood
www.pjm.com
PJM©2011
26
Double Circuit 138 kV Lines
 Conductor Size
 1033 ACSR
 Right of Way
 100 – 150 ft.
 Normal MVA Rating
 250 MVA
 Cost per Circuit Mile
 $ 0.700 M / mile
 Structure Type
 Single Pole, Steel
www.pjm.com
PJM©2011
27
230 kV Line
 Conductor Size
 1590 ACSR
 Right of Way
 100 – 160 ft.
 Normal MVA Rating
 650 MVA
 Cost per Circuit Mile
 $ 0.950 M / mile
 Structure Type
 Wood H-Frame, Steel
www.pjm.com
PJM©2011
28
345 kV Line
 Conductor Size
 2167 ACSR
 Right of Way
 140 – 160 ft.
 Normal MVA Rating
 1650 MVA
 Cost per Circuit Mile
 $1.5 M / mile
 Structure Type
 Wood H-Frame, Steel
www.pjm.com
PJM©2011
29
500 kV Line
 Conductor Size
 2493 ACSR (bundled)
 Right of Way
 160 – 200 ft.
 Normal MVA Rating
 2700 MVA
 Cost per Circuit Mile
 $ 1.8 M / mile
 Structure Type
 Lattice Tower, Steel
www.pjm.com
PJM©2011
30
756 kV Line
 Conductor Size
 1351 ACSR (4 conductor
bundled)
 Right of Way
 200 – 250 ft.
 Normal MVA Rating
 4000 MVA
 Cost per Circuit Mile
 $ 2.5 M / mile
 Structure Type
 Lattice Tower, Steel
www.pjm.com
PJM©2011
31
Underground Cable Standards
Underground
Cables
Voltage
Cable Size
(kcmil)
Right of Way
Width
Typical
Normal
Rating (MVA)
Order of
Magnitude
Installation
Cost per
Circuit Mile
(Millions)
69 kV
1500 Copper
High Pressure
Oil Filled Pipe
Type cable
N/A*
119
$ 1.2 / mile
115 kV
1500 Copper
High Pressure
Oil Filled Pipe
Type cable
N/A*
180
$ 1.5 / mile
138 kV
1500 Copper
High Pressure
Oil Filled Pipe
Type cable
N/A*
200
$ 1.8 / mile
230 kV
2500 Copper
High Pressure
Oil Filled Pipe
Type cable
N/A*
406
$ 4.0 / mile
345 kV
2500 Copper
High Pressure
Oil Filled Pipe
Type cable
N/A*
627
$ 6.0 / mile
*Assumed to be installed in existing roadway right-of-ways; minimum access
requirements and respective clearances to adjacent underground utilities would apply
www.pjm.com
PJM©2011
32
Underground Cable Standards
(Miles)
PJM MidAtlantic
69 kV
8,014
4,618
3,290
106
115 kV
4,485
2,127
22
2,336
138 kV
16,310
1,744
14,502
64
230 kV
7,456
4,669
351
2,436
345 kV
7,228
232
6,995
N/A
500 kV
4,919
2,900
882
1,137
765 kV
2,110
N/A
2,110
N/A
Voltage
www.pjm.com
PJM
(Miles)
PJM©2011
PJM WEST
PJM SOUTH
(Miles)
(Miles)
33
Transmission Paths (Distribution System)
• Exercise TO1-1.1
www.pjm.com
PJM©2011
34
Features of the Transmission System
• Generating Stations
– Source of the power (Car out of driveway)
• Transmission Lines
– Path of power flow (Freeway)
– Naming Conventions vary by company
• Number, Terminals, Voltage Level
www.pjm.com
PJM©2011
35
Features of the Transmission System
• Buses
– Points of connection (Cloverleaf)
– Many breaker configurations
•
•
•
•
Straight
Ring
Breaker and a half
Double bus/double breaker
Buses
www.pjm.com
PJM©2011
36
Features of the Transmission System
• Circuit Breakers
– Switch to interrupt the flow of current in a circuit (Car
accident or police stop)
• Transformers
Circuit Breaker
– Used to transform voltage from one level to another (onramp or off-ramp)
www.pjm.com
PJM©2011
37
Features of the Transmission System
• Other Devices
–
–
–
–
Phase angle regulators
Disconnects
Capacitors
Reactors
• Exercise TO1-1.2
– Use PJM 500 kV one-line on following slide…..
www.pjm.com
PJM©2011
38
www.pjm.com
PJM©2011
39
Summary
• List the purpose and functions of the transmission
system.
• Distinguish between the transmission system, the
sub-transmission system and the distribution system.
• Given a simple one-line diagram, identify the major
features of the PJM transmission system including:
– Lines, buses, and generating stations
www.pjm.com
PJM©2011
40
System Voltage and VAR
Characteristics
TO1-2
www.pjm.com
PJM©2011
41
Lesson Objectives
• Identify situations which may cause the system
voltage to drop below accepted standards.
• Identify situations which may cause the system
voltage to rise above accepted standards.
• List the MVAR sources and sinks on the power
system.
• Explain how system capacitance supplies MVARS to
the system.
www.pjm.com
PJM©2011
42
Lesson Objectives
• Define Surge Impedance Loading and state its
significance to system operation.
www.pjm.com
PJM©2011
43
System Voltage Characteristics
• Relationship between reactive flow and voltage
– Voltage levels most affected by
• VAR generation/absorption
• Reactive (MVAR) flow distribution
– Large reactive flows cause large voltage drops
– Large voltage differences cause large reactive flows
Reactive Power (MVAR) are required for Real Power (MW) to flow.
www.pjm.com
PJM©2011
44
System Voltage Characteristics
• Voltage profile
– On most lines voltage decreases from sending to receiving
end of transmission line.
www.pjm.com
PJM©2011
45
System Voltage Characteristics
• a = angle of voltage
• b = angle of current
• P = real power = VIr = VI cos(a-b)
Q=VIsin(a-b)
• Q = reactive power = VIx = VI sin(a-b)
• S = complex power = VI cos(a-b) +jVI sin(a-b)
• power factor = cos (a-b)
Var
(a-b)
P=VIcos(a-b)
www.pjm.com
PJM©2011
W
46
System Voltage Characteristics
• Factors affecting voltage
– VAR supply
• Excess VARs on system, voltage will rise
• Shortage of VARs on system, voltage will decrease
– VAR Sources
• System capacitance
• Capacitor banks
• Generators (lagging)
www.pjm.com
PJM©2011
47
System Voltage Characteristics
• Factors affecting voltage (continued)
– VAR loads
•
•
•
•
•
Motors
VAR losses
Generators (leading)
Reactors
Transformers
– Power (MW) Flow
• Increasing load (MW) causes larger I2R loss and IR voltage drop
www.pjm.com
PJM©2011
48
System Voltage Characteristics
• Factors affecting voltage (continued)
– Reactive (MVAR) Flow
• Increasing reactive (MVAR) flow causes larger I2X loss and IX
voltage drop
• Voltage drop due to reactive flow is larger than for real power flow
• VARs don’t travel well.
– Solar Magnetic Disturbance
• Can cause a large VAR requirement in transformers
• May cause tripping of capacitor banks
– MVAR Simulation on Powerworld
H:\Corporate Services\Training\Powerworld Cases\Chapter 2\Problem 2_24.pwb
www.pjm.com
PJM©2011
49
System Voltage Characteristics
• Results
– Result is constantly changing voltage profile
www.pjm.com
PJM©2011
50
System Voltage Characteristics
• Results
– For light loads, voltage can rise due to low losses and line
capacitance
www.pjm.com
PJM©2011
51
System Voltage Characteristics
• Results
– Voltage Varies with VAR supply and consumption
www.pjm.com
PJM©2011
52
VARs From Transmission Lines
• Line open at one end
– VAR flow back toward closed end
www.pjm.com
PJM©2011
53
VARs From Transmission Lines
Equation for Ferranti Effect
www.pjm.com
PJM©2011
54
VARs From Transmission Lines
• VARs supplied by charging of line
MVARs Supplied by Lines and Cables
www.pjm.com
Voltage
Transmission Line
765 kV
4.6 MVAR/Mile
500 kV
1.7 MVAR/Mile
345 kV
0.8 MVAR/Mile
15–30 MVAR/Mile
230 kV
0.3 MVAR/Mile
5-15 MVAR/Mile
115 kV
0.1 MVAR/Mile
2-7 MVAR/Mile
PJM©2011
Transmission Cable
55
VARs From Transmission Lines
Attachment B - Transmission Operation Manual
www.pjm.com
PJM©2011
56
VARs From Transmission Lines
Attachment B - Transmission Operation Manual
www.pjm.com
PJM©2011
57
VARs From Transmission Lines
Attachment B - Transmission Operation Manual
www.pjm.com
PJM©2011
58
VARs From Transmission Lines
550
KEYSTONE-JUNIATA 5004
Keystone
V2 =
118
3.1
196.5
514.5 14.5
5004 Line
216.9
540.4 15.4 238.0
566.1 16.1
Juniata
525 kV
www.pjm.com
PJM©2011
59
VARs From Transmission Lines
550
KEYSTONE-JUNIATA 5004
118
Keystone
3.1
196.5
514.5 14.5
5004 Line
216.9 MVAR
216.9
540.4 15.4 238.0
566.1 16.1
Juniata
0 MVAR
528.1 kV
V1 = 540.4 kV
www.pjm.com
PJM©2011
60
VARs From Transmission Lines
• Line connected to load
– Power (MW) losses increase with load
– Reactive (MVAR) losses increase with load
MW Flow increases
MVAR Flow increases
Load
Load
increases
www.pjm.com
PJM©2011
61
VARs From Transmission Lines
• Surge Impedance Loading
– Loading point where VAR losses on a line equal VARs
generated by line
www.pjm.com
PJM©2011
62
VARs From Transmission Lines
• Surge Impedance Loading
–
–
–
–
www.pjm.com
765 kV = 2100 MW
500 kV = 850 MW
345 kV = 400 MW
230 kV = 135 MW
PJM©2011
63
VARs From Transmission Lines
MVAR absorbed by
Transmission Line
MW
0
400
600
850
1000
MVAR supplied by
Transmission Line
1400
1800
Long 500 kV line
Short 500 kV line
Limited by charging
MVAR
Surge Impedance Loading Example
www.pjm.com
PJM©2011
64
VARs from Transmission Lines
1.0 pu
1.0 pu
Line loaded above SIL
MVAR
MVAR
Required
Required
Voltage Profile
As line loading increases:
Reactive losses increase proportional to I2
Reactive supply decreases proportional to V2
VARs from Transmission Lines
1.0 pu
1.0 pu
Voltage Profile
MVAR
MVAR
Supplied
Supplied
Line loaded below SIL
As line loading decreases:
Reactive losses decrease proportional to I2
Reactive supply increases proportional to V2
VARs From Transmission Lines
• Switching Operations
– Open one end
• Provides VARs to closed end of line due to line capacitance
MVAR Flow
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VARs From Transmission Lines
• Switching Operations (continued)
– Open both ends
• Removes that line from service
• No longer supplies VARs (high voltage) or uses VARs (low voltage)
– Switching Over-voltages
• Very high voltages which occur for a short duration
• Can be handled in insulation design or use of surge suppression
devices
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VARs From Transmission Lines
• Lightning Over-voltages
–
–
–
–
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Much more severe than switching surges
>1000 kV
Can cause insulation failure or flashover
Controlled by surge arrestors or lightning rods
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Summary
• Identify situations which may cause the system
voltage to drop below accepted standards.
• Identify situations which may cause the system
voltage to rise above accepted standards.
• List the MVAR sources and sinks on the power
system.
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Summary
• Explain how system capacitance supplies MVARS to
the system.
• Define Surge Impedance Loading and state its
significance to system operation.
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Distribution Factors and Generation
Shift Factors
TO1-3
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Lesson Objectives
• Define a transmission line distribution factor.
• Briefly describe the application of distribution factors
for system operation.
• Given appropriate distribution factors, analyze the
impact of taking a line out of service.
• Define a generation shift factor and describe its
application for system operation.
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Lesson Objectives
• Given appropriate generation shift factors, analyze
the impact of a shift in generation.
• Define the concept of $/MW effect and its
application in the new operating environment.
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Introduction to Distribution Factors
• Definition
– The percentage of flow currently on a line that will transfer
to another line as a result of the loss of the first line
• Characteristics of Distribution Factors
–
–
–
–
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Determined by line impedances
Computer generated
Expressed as a decimal number of 1.0 or less
Distribution factor for a line for the loss of itself is -1.0 if
line flow is positive.
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Introduction to Distribution Factors
• Characteristics of Distribution Factors (continued)
– Can be a positive or negative factor
– Sum of all distribution factors in a closed system is zero
• Formula:
• New flow on line = Previous flow + [(Dfax) (Flow on outaged
facility)]
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Example Simple Calculations
For the loss of line C:
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Dfaxb= 0.5
Dfaxc = -1.0
Dfaxd = 0.3
Dfaxe = 0.2
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Example Simple Calculations
Let’s do Exercise TO1_3.1!
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Applications of Distribution Factors
• Line Outages
– Use distribution factors to estimate how power will flow
and predict any flow problems which may result from a
line outage.
• Generally performed by computer tool
• Flow Analysis
– Used to predict the results of losing a specific piece of
equipment (Contingency analysis)
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PJM Distribution Factor Table
• Try Exercise TO1_3.2.
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Generation Shift Factors
• Similar to Distribution Factors
– Decimal Fraction
– Used to analyze the effect of generation shifts on MW flow
– Does NOT add up to 0
• Definition
– Fraction of change in generation MW output that will
appear on a line or facility
– Used to predict the effect of generation changes on
transmission line flow
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Generation Shift Factors
• Formula
New flow on line = Previous flow + [(Gen Shift Factor)(Amount of MW
Shift)]
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Generation Shift Factors
Line 3 = 500 MW
Increase Gen A by
100 MW.
What is resultant
flow on Line 3?
LINE 5
New Flow = 500 MW + (.12)(+100MW) = 512 MW
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Generation Shift Factors
Line 3 = 512 MW
Now, Generator C is
decreased by 100 MW.
What is resultant flow
on Line 3?
LINE 5
New Flow = 512 MW + (-0.6)(-100MW) = 572 MW
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Generation Shift Factors
Try Exercise
TO1_3.3!
LINE 5
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$/MW Effect
• Adjustment of Shift Factors due to Economics.
• Definition
– $/MW Effect = (Current Dispatch Rate - Unit Bid) / Unit
Generator Shift Factor
– Unit with lowest $/MW effect is redispatched when system
is constrained.
– Other unit operating constraints taken into account (I.e.
min run time, time from bus, etc)
– In an emergency, economics takes the “back seat” to
reliability.
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$/MW Effect
Line #1 is overloaded!
Dispatch rate = $20
Unit D = $21
Unit B = $40
Which unit would you
raise to alleviate the
overload?
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$/MW Effect
Unit D = ($20-$21)/(-.12)
= $8.33/MW
Unit B = ($20-$40)/(-.2)
= $100/MW
Select Unit D even
though effect is less!
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$/MW Effect
• Let’s do Exercise TO1_3.4 on $/MW Effect.
• 2 PowerWorld Simulations on Loop Flows and Power
Transfer Distribution Factors (PDTF)
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Summary
• Define a transmission line distribution factor.
• Briefly describe the application of distribution factors
for system operation.
• Given appropriate distribution factors, analyze the
impact of taking a line out of service.
• Define a generation shift factor and describe its
application for system operation.
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Summary
• Given appropriate generation shift factors, analyze
the impact of a shift in generation.
• Define the concept of $/MW effect and its
application in the new operating environment.
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Module Summary
• Review the purpose and function of the transmission
system.
• Review basic system voltage and VAR characteristics
• Demonstrate basic distribution factor theory.
• Determine power flows utilizing system distribution
factors and generation shift factors
• Introduce the concept of $/MW effect.
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Questions?
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Disclaimer:
PJM has made all efforts possible to accurately document all
information in this presentation. The information seen here
does not supersede the PJM Operating Agreement or the
PJM Tariff both of which can be found by accessing:
http://www.pjm.com/documents/agreements/pjmagreements.aspx
For additional detailed information on any of the topics
discussed, please refer to the appropriate PJM manual
which can be found by accessing:
http://www.pjm.com/documents/manuals.aspx
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95