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August 14, 2003 Wasn't the First Time
<br /> Major Bulk Electric System Power Outages
<br /> DATE.':"'`' STATESIPROVINCESAFFECTED COST_ O r
<br /> & DESCRIPTION -i EC E�'•F.' r .
<br /> November 9, 1965 Virtually all of New York, Connecticut, Massachusetts,
<br /> 30,000,000,ores iqw Up to 13 - `h
<br /> 5 Rhode Island, and small segments of northern PA and 20,000MWof t:! hours',�;f`'f`'U
<br /> .a
<br /> northeastern NJ;substantial areas of Ontario, Canada demand t�e r S'
<br /> •
<br /> •A backup protective relay ?artkg ife z
<br /> ackup pro lay operated to open one of fit% e _rt`> c i
<br /> 230-kV lines taking power north from the-Beck plant-in_ < ,r : --44--
<br /> Ontario to the Toronto area.When the flows redistributed ,=a-9 ;. ;.
<br /> instantaneously to the remaining four lines,they tripped,- _7- - s^
<br /> out successively in a total of 21/2 seconds. The resultant - - _ - -
<br /> power swings resulted in a cascading outage that blacked - -
<br /> i out much of the northeast.
<br /> 4 i
<br /> July 13,1977 New York City -9,000,000 people; - Up to 26 • =z
<br /> •A series of events triggering the separation and total col-- +6,000 MW of 1 '' boars, -
<br /> lapse of the Con Ed system began when two 345 kV liner demand "-'!- y,
<br /> F, c' -onsa,iommon tower lme in Northern Westchester were?f rfS^ " rrl
<br /> snuckiiy lightening and tr`ip`ped out Over`the next hota,;
<br /> _ the Cori Ed dispatcher tried to save his system, but in the" y '' ifP
<br /> end the system 4 : sy electrically separated from surrounding t s _ " �j r . l ittr-,:et
<br /> systems and collapsed. Generation inside New York City 4... s, it-4-73 •r: tut -.
<br /> was not adequate, by itself to serve the load inside the - '
<br /> city.
<br /> R+t �
<br /> July 2,1996 Arizona, California, Colorado, Idaho, Montana, 2,000,000(10 70.,! From a few. •:,-
<br /> Nebraska,Nevada,New Mexico,Oregon,South Dakota, "of the customers in"- • minutes to f`ek;-
<br /> Texas, Utah, Washington and Wyoming in the UnitedA atheWestetotti5 s� `sevenf
<br /> States;Alberta and British Columbia in Canada;and Baja •:Interconnection);;‘, Iowa;'> '°`.Pt„
<br /> a.>
<br /> California Norte in Mexico. ' '. 41,850 MW of -wirm psi
<br /> •The outage began when a flashover occurred between a demand z ifs s 7-44€t.
<br /> I! 345,000-volt transmission line and a tree that had grown - -. .,.i
<br /> I too close to the line in Idaho. Protective devices detected -
<br /> the short and de-energized the line.A protective relay on a
<br /> parallel transmission line also detected the fault and erro-neously opened the second line. Disconnecting these two
<br /> lines nearly simultaneously greatly reduced the ability of _
<br /> the system to carry power away from a near-by generating - .. 717k
<br /> plant, causing other protective devices to shut down two t =` - '- 3=.
<br /> of the four generating units at that plant. With the loss of 2- 't:'
<br /> i
<br /> these two units, frequency in the entire Western - - _.
<br /> Interconnection began to decline. For 20 seconds the sys-
<br /> tem struggled to remain in balance, but the system was
<br /> becoming unstable. At this point, automatic protection
<br /> systems were initiated to allow the system to bend, but not
<br /> break. Scattered customer outages occurred to help the
<br /> system regain balance. The interconnected system separat- _ --i
<br /> ed into five pre-engineered islands designed to minimize '
<br /> .--
<br /> customer outages and restoration times. .r.;. •-
<br /> August 10, 1996 Arizona, California, Colorado, Idaho, Montana, 7,500,000 cus- - Up to 9
<br /> Nebraska, Nevada, New Mexico, Oregon,South Dakota, tomers;28,000 hours
<br /> Texas,Utah MW of demand
<br /> •Triggered by a combination of random transmission line shed by underfre-
<br /> outages and resulting system oscillations, the Western quency load-shed- I
<br /> Interconnection separated into four electrical islands, with ding relays '``-
<br /> significant loss of load and generation.
<br /> 18 � 4th Quarter 2003
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