THE COLOMBIAN 2007 BLACK OUT

c. A. Ruiz, N. J. Orrego and J. F. Gutierrez

area caused by the failure of some power device for example:
Abstract--On April 26th, 2007, at 9:58 a.m., a fault on the a line short circuit or the outage of a substation braker.
colombian power system caused by maintenance in the 230 kV In Colombia, it could be as a result of a terrorist attack to
Torca Bus gave origin to black out. the energy infrastructure, but in other countries, could be
The consequent loss of those important branches caused caused by investment delays as a result of a tight power
cascading outages of tie lines that turned out in cascade events
system regulation that leads to devices obsolescence.
that concluded in an electrical separation with Ecuador, causing
many economical losses for the country. The Colombian power A blackout can be produced by load increments or
system frequency suffered a mayor imbalance that leaded to a decrements beyond a safe level, if the protection system fails
disoperation of the automatic load shedding system and this in shedding load or disconnecting generators in order to keep
resulted out in the Colombian blackout. the load flow in a secure value.
This paper provides a short description of the power system A blackout can be prevented if the vulnerability of the
analysis operation and of the main events that triggered the system is determined in the planning stages of the operation in
blackout, identifying some of the main causes that could lead to
order to establish the actions that must be followed to assure
those events.
Index Terms-- Blackouts, power system security, power the safe operation of the system.
system stability, power system restoration. CND-XM, the Colombian system operator issues every day
the colombian generation dispatch considering the system
I. INTRODUCTION reliability using the VERPC (Valor Esperado de

W HEN cascading outages happen the lights tum out and Racionamiento Programado Condicionado - Expected Value
everything stops. With the facility down and in the Of Conditioned Loss Of Load) in order to reduce lost of load
dark, there is nothing to do but to sit and wait until the utility supply and providing energy in an economical way.
company finds out the problem and solves it. This process
usually takes only few minutes but sometimes it takes hours II. ANTECEDENTS

and to complete system restoration, it can even take days. There are about 82 main blackouts registered in countries
Blackouts are by sure the most troublesome problem that a as: United States, France, Canada, Brazil, Portugal, Chile,
utility company will have to deal with. Statistics show that Mexico, Italy, Sweden and Colombia among others. In the
power failures are, in general, a strange situation in most Fig. 1 it is presented the incidence of blackouts from 1966 to
countries. Blackouts are also short in duration. Studies have present time. It can be seen that from 2003 the occurrence of
shown that 50 percent of blackouts last to 6 s. And 35 percent those contingencies is been drastically increasing. Notice that
are less than 11 min long. These failure times are not a cause in this year it is been registered 8 events by may [2-10].
to concern for most commercial users, but for those industries
where there are computer-based operations, transportation 18 bleck outs In the world 17
control systems, medical facilities, and communications sites 16
they can be a problem.
When service continuity is critical, redundancy must be
14
I la 12
carried throughout the system. It means that some sites should
never depend upon one critical path for ac power. For
12

10
J
15
example, if the facility is fed by a single step-down
transformer, a lightning flash or other catastrophic event could
8

6
I•
::I
8

result in a transformer failure that would bring down the

electric supply.
A blackout is the total failure of the electric supply in an

This work was supported by the Universidad Nacional de Colombia and

XM Los Expertos en Mercados an ISA Group enterprise.
Cesar Augusto Ruiz is from Universidad Nacional de Colombia sede Fig. 1: Blackouts by year
Manizales (e-mail: caruiz@3g.telme.sg).
Jorge Fernando Gutierrez is from Universidad Nacional de Colombia,
Serle Manizales(e-mail: jfgutierrez@unal.edu.co)
Some of the effects (duration and people affected) of the main
Nolasco de Jesus Orrego is from XM - ISA, Medellin, (e-mail: events are presented in Table I.
njorrego@xm.com.co)

978-1-4244-2218-0/08/$25.00 ©2008 IEEE.

 2

system that affected the whole country for about 1,5

hours [4].
TABLE I.
CIVILIANS AFFECTED BY BLACKOUTS 7. Colombia on April 26, 2007. This event affected
time civilians almost the whole country and will be detailed in the
year country next section.
(hours) (millions) 8. Argentina on May 17th, 2007. A fire in a Transener
1989 CANADA 9 6 substation caused a blackout that lasted for 3 hours
1999 BRASIL 9 90 affecting a mayor area in Buenos Aires.
2003 USA-CANADA 9 50 9. Spain Barcelona on July 23,2007. The whole city was
2003 CANADA 5 4,3 affected and in some parts of it the blackout lasted
2003 ITALY 24 56 for 78 hours.
2005 JAVA ISLAND 7 100
2007 COSTA RICA 1,5 5 III. THE COLOMBIAN SCENARIO BEFORE THE BLACKOUT
2007 COLOMBIA 4,5 38 The system operator of the Colombian power system
2008 CANADA 3 0,1 (Centro Nacional de Despacho - CND-XM) solves everyday
2008 AUSTRALIA 72 0,42 the energy dispatch process observing the market regulator
reliability guidelines. In this process it is included a blackout
In Fig. 2, it is presented the percentage of blackouts by risk equalizing policy called VERPC. CND must find a
country. It can be seen that developed countries are taking the solution of the dispatch problem so that the expected relative
bigger share of the main blackouts. load shedding in the different sub-areas of the interconnected
system (SIN - Sistema Interconectado Nacional) are equalized
BLACK OUTS PERCENTAGE among the different sub-areas and minimized. This criteria is
equivalent to the worldwide well-known N-l criteria [13].
On March 15 th , 2007 ISA the main transmission system
operator in Colombia, announce about some maintenance
works on Torca substation to CND. Those works will be done
on line with the substation equipment energized. That
substation is double bus and a sectioned transfer bus. That
maintenance was approved to be done on April 26 th • On April
25 th the system operator, solved the day-ahead energy dispatch
considering the risk of failure on the 230 kV Torca - Guavio
power line during the maintenance, and approved that
maintenance to be done by 9:20 AM.
Fig. 2: Blackouts density by country On Fig. 3, can be seen the normal state before the
maintenance. The power line flows were below the limits and
A list of the most important events, by their socio - the frequency and voltages were between their normal values.
economic impacts should include the following:
1. USA Northeast blackout on November, 1965.
2. USA New York blackout on July 13, 1977. During
this event there were disturbs and riots registered
along the city.
3. Canada - Hydro Quebec on March 13, 1989. It was
caused by GMD (Geomagnetic Disturbances) and
was one of the largest ever recorded. The entire
Quebec Interconnection was blacked out as a result
of this disturb 6 million people were affected during
about 9 hours.
4. USA California on 2000 - 2001 experienced several
power shortages as a result of its electricity
deregulation process.
5. U.S.-Canada blackout on August 14,2003. This event
affected 50 millions of people in 8 American states
and 2 Canadian provinces and 63 GW of load was Fig. 3. SIN state before contingency
curtailed [7].
6. Italy on September 28th, 2003. As a result of two On Fig. 4, can be seen the transfer limits between areas
Swiss power lines overloaded a loss of synchronism (blue) and the real values before contingency (white). At that
between the Italian system and the UCTE power moment the system was generating 7083 MW and there were
 3

not any international power transfers with Ecuador. This In spite of that situation, Guavio and Chivor, the biggest
power interchange with Ecuador it is been done using the generation plants in that area were on line, but the
Jamondino - Pomasqui tie line and the political agreement transmission corridor that carries out the energy was overload
between the countries is called TIES. so frequency and bus voltages were decreasing beyond the
safe limits causing this area insulation from the rest of the
system. That caused that thermo plants of Paipa and Yopal
were shut down. At that moment there was a lost of generation
close to 2100 MW that corresponds to 31 % of the load (6644
MW). That causes separation of the network into islands and
the disconnection of:
• Guavio-Tunal transmission line
• Tunal- Reforma transmission line
In Fig. 6 can be seen that the disconnection of those lines
causes the islanding of Boyaca and Santander regions.
Disparo de Guavio - Tunal/Reforma Boyee' y santanderes

.~ .a:".,~".~~~

Fig. 4 Pre-contingency power flows between areas

IV. EVENT DEVELOPMENT

At 09:58 during the maintenance on one the Torca bus 1
disconnect switch L 141 an operation of the M240 circuit
breaker that couples the substation buses occurred. That
operation caused the desenergization of the entire substation
and the circuit opening of Chivor 1 y 2, Bacata 1 y 2, Guavio
1 y 2 and 230/115 kV Torca transformers 2, 3 y 4. Those lines
and transformers are the power supply to Bogota [11]. In Fig. 7, is presented the frequency evolution during the
A cascading event result as a consequence of Torca contingency. Note the frequency deviations between the
outage. First, Guavio-Circo power circuits were opened as can system islands. The oriental area were experience over
be seen on Fig. 5. That outage caused low voltage levels in frequency and for rest of the country the lost of generation
some bars (blue), overloads flow on 220kV Villavicencio - caused a low frequency.
Tunal transmission line (red) and the outage of Termo Zipa
gen~ration plant [11].

.. •
....
~f~·---~.,.~--~---~--~...L-_-~

,. ..
" " m 1_'_'-- ..
• .
-'""
tr,,'IQ'::-CA.·...
T....-;~T
'..:-~t

......:.:hlO._I._'.-.
:~~
~· 1lQ!

.... .........,.Ull"'"'*_~.·ot:

Fig. 7 Frequency response during the contingency

After that, Colombia and Ecuador were insulated by the

opening of Jamondino-Pomasqui circuits. Finally, other plants
of the Colombian system were shut down in the sequence
Fig. 5 Guavio-Circo transmission line outage. described below:
Calderas Generator 1, at 9:58.42.885
 4

Calderas Generator 2, at 9:58.43.130 VI. CONCLUTIONS

Guaca Generator 3, at 9:58.43.000 The Colombian power system operator XM, after analyzing
San Carlos Generator 8, at 9:58.43.940 this event, issued a document with some conclusions about the
San Carlos Generator 6, at 9:58.44.240 system behavior during this contingency and its restoration
San Carlos Generator 5, at 9:58.44.290 process [11]. Some of those conclusions are presented below:
Tennocentro Generator 1, at 9:58.51.708 • The load shedding system EDAC system and the
Tennocentro Generator 2, at 9:58.51.951 primary and secondary generation reserves had
Playas Generator 1, at 9:58.50.567 operated as they were intended to do.
Playas Generator 3, at 9:58.59.393 • It is necessary to install a contingency alann device in
Playas Generator 2, at 9:58.50.890 order to improve time responses during contingencies.
That lost of generation caused the frequency response • It is necessary to reinforce communication channels
presented in Fig. 8. between the regional transmission operators and the
lOi...--------..".......--------------, main system operator increasing its redundancy and
developing new communication protocols.
• It is important to analyze the system vulnerability to
the substation failure in order to know which of them
. ...·_-·--·----·------··-·;
.o+---------------~
are critical
Iss
J•• VII. ACKNOWLEDGMENT
The authors gratefully acknowledge the contributions of
!ltoi----------"",...,.--------~lJIIr_----l
Corredor P., Murcia A., et Al and XM for their work on the
tlU+-------~IloOoI.JO\UUi..--------~---I original version of this document.
t60+-------...---.....--_...------,---__- ~
o
VIII. REFERENCES
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Colombiano", 2007
[2] US-Canada Power System Outage Task Forces. Final Report on the
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could not be corrected by the load shedding system recommendations. April 2004
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[4] Berizzi A. The Italian 2003 blackout, IEEE PES General Meeting,
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http://www.energie-schweiz.ch. November 2003.
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contingency guides developed previously were used in the Denver, CO, June 6-12, 2004.
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developed by XM and the system agents and are continually Eastern Denmark. IEEE PES General Meeting, Denver, CO, June 6-12,
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actualized. [11] ISA XM. Evaluacion del Esquema de Desconexion Automatica de Carga
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nonnal. The restoration process duration can be considered Despacho Direccion Planeacion de la Operacion XM Mayo 28, 2007
[12] NERC. August 14, 2003 Blackout: NERC Actions to Prevent and
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• 07/12/2006 Auckland, New Zeeland took 10 hours. [13] Lopez L 1. M., Murillo S C. E. Gutierrez G J. F. A Contingency-Based
• 08/22/2005 Iraq took 7 hours Security-Constrained Optimal Power Flow Model for Revealing The
• 11/25/2005 Musterland, took six days because of the Marginal Cost of a Blackout Risk-Equalizing Policy in the Colombian
Electricity Market. 2006 IEEE PES Transmission And Distribution
heavy weather conditions. Conference and Exposition Latin America. 2006.
But those 4,5 hours of inactivity had a cost of nearly US$ [14] ELECTRICITY RESTRUCTURING 2003 Blackout Identifies Crisis
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Recommendations to Prevent Future Blackouts based on TEPCO's
Experience. IEEE PES General Meeting, Denver, CO, June 6-12, 2004.
 5
[16] Van Hulst N. Lessons Learned from the Power Outage in North America
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IX. BIOGRAPHIES

Cesar Augusto Ruiz Beltran: He received a degree in

electrical engineering from the Universidad Nacional de
Colombia - Manizales in 2008. He was a passant student at XM
S.A E.S.P, owned by Interconexi6n Electrica S.A (ISA).
Currently, his working as an engineer at CODENSA S.A. ESP.

Nolasco De Jesus Orrego: studied electrical engineering at the

Universidad de antioquia, then he studied at the University of Wisconsin-
Madison, where he obtained a Master of Science in electrical power systems,
he is currently working at XM S.A E.S.P, owned by Interconexi6n Electrica
S.A (ISA).

Jorge Fernando Gutierrez Gomez: studied electrical engineering at the

Universidad Industrial de Santander, where he also obtained a Master of
Science in electrical power systems; he is currently a full time professor at the
Universidad Nacional de Colombia Sede Manizales. His main areas of
interests include power systems operation and control, transmission lines and
energy markets.