Transcript Then Versus Now: A Comparison of Total Scheme Complexity

Then Versus Now: A Comparison
of Total Scheme Complexity
Bob Morris, Roy Moxley, and Christina Kusch
Schweitzer Engineering Laboratories, Inc.
Copyright © SEL 2009
Protection Fails to
Clear Fault in the
Prescribed Time
52
50A
Top Event
50B
OR
Logic Gate
Basic
Events
52
AND
SimpleScheme
Fault Tree
Analysis
Breaker
Fails
CT
Fails
Relay
A
Battery Wiring
Fails
Fails
Relay
B
Real-World Transmission Scheme Is
More Complex
OR
3
Protection Fails to Trip and
Reclose for a Line Fault
2
8X + 2X + 2X
Protection
8X3 + 3X2 + 3X
Reclosing
OR
8X3 + 2X2
AND
X2 + X
X + 4X2
IRD
OR
2X
X2
KD
OR
4X2
2X
RC
TD-5
Leading to X
More Complex
Fault Tree
AND
X
AND
KD
KD
2X
2X
CVE
NGV
X
X
Connections Are Part of Critical Path
Many Benefits to Reducing Yard Wiring
8X3 + 3X2 + 3X
Protection Fails to Trip
for a Line Fault
“Critical”
Path Wiring Is
Substantial
Part of Total
Wires
X +X
OR
8X3 + 2X2 + 2X
OR
8X3 + 2X2
AND
X + 4X2
IRD
2X
2
OR
KD
X2
OR
4X2
2X
RC
AND
TD-5
AND
X
X
KD
KD
2X
2X
CVE
NGV
X
X
“Unavailability” Time Is
Function of Multiple
Inputs
• MTBF
• Detection time
• Time to repair
Mean Time to Failure
• 30–400 years
• Not “tested” into product
• Environmental impact
Detection Time
• Most important factor
• Self-test vs. scheduled test
Time to Repair
• How difficult is repair?
• What else is out of service during repair?
Guide to Fuse Replacement
97 A
243 A
612 A
1482 A (Slow Blow)
Subcomponents and Adjustments
Are Part of Scheme Complexity
Even Subcomponents
Have Subcomponents
Microprocessors:
More Components, Fewer Adjustments
la(prot)
lb(prot)
lc(prot)
I neutral
Va
Vb
Vc
V neutral
V busbar
Discrete Status
and Alarm
lb(meas)
lc(meas)
Merging Unit
Concept
Merging
Unit
Clock Input
(If Required)
Power
Supply
la(meas)
Digital
Communication
Advanced CT Application Topologies
MV and HV
GIS Switchgear
IEEE C37.92
IEC 61850-9-2
IEC 61850: Switched Ethernet Station
and Process Bus From Beginning
Ethernet
Ethernet
IEC 61850 Defines Suite of
Protocols – Not Just One
Sampled
Values
(Multicast)
Generic
ObjectOriented
Substation
Event
SV
GOOSE
(Type 4)
(Type 1, 1A)
Time
Synchronization
(Method 2)
Core
ACSI
Services
Generic
Time
Substation Synchronization
Status Event
(Method 1)
Time
Synchronization
(SNTP)
MMS Protocol
Suite
GSSE
(Type 2, 3, 5)
(Type 1, 1A)
(Type 6)
UDP / IP
ISO / IEC 8802-3 Ethertype
ISO / IEC 8802-3
GSSE
T-Profile
GPS
IRIG-B
Sampled Values on LAN
• Takes decentralization one step further
• Separates sampling
physically from
♦
Measurement
♦
Metering
♦
Calculation
• Publishes constant message
at predefined rate
• Sends SV to multiple subscribers
Yard
Physical
Equipment
Terminal
Block
44 Wires
House
Marshalling
Cabinet
44 Wires
44 Wires
Traditional Topology:
Wires Vs.
Components
Terminal
Block /
Test Plug
Relay
44 Wires
Yard
Terminal
Physical 44 Wires
Block /
Equipment
Test Plug
Relays in Yard:
Fewer Wires,
Where Do You
Test?
44 Wires Relay
Relay-Based Process Bus System
Process
Level
Instrument
Transfer
Merging
Unit
50, 51, 21
Breaker
Breaker
Controller
Bay
Level
Station
Level
Time
Source
Ethernet
Switch
HMI
87
BFR
Ethernet
Switch
Station
Controller
Merging Unit Reduces Wire Count,
Increases Device Count
House
Yard
Physical
Equipment
Terminal
Block /
Test Plug
44 Wires
Merging
Unit
44 Wires
1 Cable
Switch or
Processor
Relay
1 Cable
Yard
House
Terminal
Physical 44 Wires Terminal 24 Wires Marshalling 24 Wires
Block / 24 Wires Relay
Cabinet
Equipment
Block
Test Plug
20 Wires
Moving I/O
to Yard:
Replace Wire
With Fiber
I/O
Transceiver
1 Cable
Where Should Testing Be Performed?
It Is Colder (or Hotter) Outside
Conclusions
• Number of wires and number of devices are
key elements of complexity
• Reduction of wire count AND device count
both need consideration
Conclusions
• Firmware complexity and qualitative
measures are as significant as hardware
measures
• Measuring and evaluating scheme
complexity are how we improve