Transcript T&D Show - unipi.it

BLACKOUT AMERICANO E ITALIANO:
LUNEDÌ, 10 MAGGIO 2004
ROMA
August 14th NE Blackout and Common
Roots of Blackouts
Damir Novosel, PhD
President
KEMA Inc., T&D Consulting
[email protected]
System Blackouts: Description and Prevention
2
1.
US Grid
2.
Descriptions of the August 14th NE Blackouts
3.
Common Roots of Blackouts
4.
Conclusions
The US at night: the transmission grid
Sparse load:
Sparse
network
3
140 GW
Dense load:
Dense
network
650 GW
Areas of retail competition
4
Regional reliability coordinators
5
Reliability coordinators & control areas:
Complexity
6
Regional Councils and NE Blackout Effects

ASCC
Blackout
Area
Regional Councils
7
August 14, NE USA (8 states) and
Canada (2 provinces) affected:

50 million people

34,000 miles of transmission

~290 Generating units

~61,800 MW

Restoration efforts
 A day to restore power to NY City
 Two days to restore power to
Detroit
14 August temperatures
8
Aug. 14th NE Blackout: Initial Generator Outages
9
1
10:05:44 Conesville Unit 5
375 MW
2
1:14:04 Greenwood Unit 1
785 MW
3
1:31:34 Eastlake Unit 5
597 MW
August 14th Blackout – Some Key Events
4
5
6
2:02
Stuart-Atlanta 345kV
trips due to a fault
3:05
Harding-Chamberlain
345 kV sags into a tree
3:32
Hanna-Juniper 345kV
sags into a tree, other 345 kV lines
disconnect => 16 of 135kV lines
overload and trip
9
4:06
Sammis-Star 345kV
trips on overload
10
4:09
Galion-Ohio 345kV
Central-Muskingum
11
4:09
East Lima-Fostoria 345kV
5
6
9
4
2,200 MW Power Reversal to Northern Ohio overloading the lines and
causing voltage to decline
10
August 14th Blackout - Some Key Events
14
20 Generators around Lake Erie (app.
2,174 MW) tripped
15
Michigan lines trip
16
1256 MW Generator trips
17
Transmission system separation
Another power reversal, power flow
(2,800 MW) to Northern Ohio through
Ontario and Michigan
The cascading events proceeded
including apparent voltage decline.
Cascading Failure Complete at 4:13 PM
11
August 14th Blackout - Some Key Events
33 4:10:50 Ontario
system separates from
New York
34 4:10:43 Long
Mountain – Plum Tree
(345 kV Line)
35 4:10:45 Remaining
lines between Ontario
and Eastern Michigan
separate
13
NE Blackout - Cascading Failure Complete at 4:13
14
August 14th Blackout - Power Plants Tripped
15
August 14th Blackout Cascade Sequence
16
Common Roots of Blackouts

17
Caused by multiple contingencies
with complex interactions

Usually no “single” cause

Sequence of low probability events
difficult to accurately predict

Practically infinite number of operating
contingencies, different from the
expectations of system designers

Operators cannot act fast enough
for fast developing disturbances
Pre-conditions and Factors for Blackouts

Congested grid


No lines & generators in my
backyard!
Not enough reactive support

Tight operating margins, with less
redundancy

Regulatory uncertainty

Low level of investment
in recent years

How and who to invest?

How to recover costs?
The bulk power system was not designed to
transfer large amounts of power, but to
improve network security
18
Pre-conditions and Factors for Blackouts

Inadequate right-of-way maintenance

19
FE failed to adequately trim trees

Aging equipment, prone to failures

Insufficiently coordinated equipment maintenance and
generation scheduling

Weather
(high temperatures; wind, thunderstorm, fog, etc.)
How Do Disturbances Turn Into a Blackout?
Cascading events that cause disturbances to propagate

Sequential tripping due to overloads, power swings, and voltage
fluctuations





E.g. FE lost its system condition alarm system around 2:14 pm
MISO (FE’s reliability coordinator) had an unrelated software problem and
was unable to tell that FE’s lines were becoming overloaded
Insufficient reactive support where and when required
Inability of operators to prevent further propagation

20
In some cases, protection miss-operation or unnecessary actions: incorrect
settings, uncovered application design flows, or HW failures
Inadequate or faulty EMS/SCADA system (alarm burst)


Protection involved in ~70% of blackout events in North America
Sacrifice own load or cut interties or get support from neighbors
Contributing Factors that Allow Blackout to Spread

Lack of coordinated response during developing disturbances



FE didn’t ensure the security of its transmission system because it didn’t
use an effective contingency analysis tool routinely
Lack of inadequate Special Protection Schemes to prevent
spreading of the disturbance:

Prevent further overloading of the lines

Arrest voltage decline

21
Should we help or should we separate?
Inadequate planning/operation studies


PJM saw the growing problem, but did not have joint procedures in place
with MISO to deal with the problem quickly and effectively
Initiate pre-planned separation of the power system for severe
emergencies
Conclusions

North-American Grid not designed for large transfers

Increase in the number and frequency of major blackouts

Analysis of recent disturbances reveals some common
threads among them, leading to conclusions that:


Propagation can be arrested

Impact of disturbances/outages can be reduced
Various cures to reduce the possibility of future outages

22
A need for deployment of well-defined and coordinated overall plans
(planning, operations and maintenance)