1. Todos los derechos reservados para XM S.A E.S.P. Luis Alejandro Camargo S. Wholesale Market Manager XM S.A. E.S.P. Colombian Market Stress Experiences

2. 2 Situation: Terrorism on Power Lines

3. 3 Terrorist Attacks To The Transmission Grid Terrorism against the National high voltage Grid System Attacks Towers down

4. 4 We operated “n- 55” in May of 2002

5. 5 Despite the attacks, no overall blackouts have affected the market Non-served demand (as a percentage of the annual electricity demand) Non-served demand due attacks Month % Non-Served demand

6. 6 rVoltage should not be under 90% or over 110% of nominal value (over 105% at 500 kV) rThe reactive power on generation units must follow their capacity curves rEstablish specific voltage levels on different special points/nodes on the system rThe system should maintain operating even with a three phase fault, cleared using the principal protection rGenerators must oscillate on a damp and consistent way rIf a grid element goes out, there should not be additional trips, in order to avoid cascade events Rules To Guarantee Security

7. 7 Reliability rCurrent Probabilistic Method (formerly classic N-1) Outage Probability of Elements (1 year history) Rationing caused by outage of elements Electric-Area Reliability Criterion rInformation System to Gather Data Market participants must deliver information Gathering information through ISO rDesign strategies for High Availability of equipments Minimum of events

8. 8 MARKET FUNCTIONS OPERATION PLANNING FUNTIONS Without Network & Generations Technical Characteristics ECONOMIC DISPATCH IN COLOMBIA ECONOMIC DISPATCH IN COLOMBIA Marginal Price + $ Congestions IDEAL DISPATCH Network & Generations Technical Characteristics FINAL DISPATCH REAL DISPATCH REAL TIME OPERATION Electric Analysis Settlement S1S2S3 US$/MWh Offer Price Curve for International Transaction (TIE) Day Ahead Dispatch Current Day Dispatch Price Offer's Reliability Signals

9. 9 ESTYRA – In House Application Development After the market dispatch is calculated, a electric analysis team check the system security. This can be done by: Conventional approach: (DIgSILENT - Power factory) ESTYRA Transitory Stability Estimated Overload Estimated Redispatch

10. 10 Real Time Oscillation Monitoring Frequency measure Indication of Damping Possible Generation Changes Generations Control Settings Changes (Adjust PSS) Real time Detection of Oscillation Reinforcement of the National Grid

11. 11 Real Time Oscillation Monitoring Frequency vs Damping Damping InterArea modes 0.22 Hz Colombia-Venezuela 0.45 Hz Colombia-Ecuador 0.70 Hz Coast-Central Even though about 10.000 oscillations were detected with the frequency and oscillation network – F@OSnet, 96% of them have remain below 60 seconds

12. 12 Critical factors to deal with terrorism on Power Lines Generating plants availability and coordination Reliability indexes calculation Development of international networks Probabilistic criteria for planning and operation Development of software for real time transient stability analysis Frequency and oscillation measurement network Development of AGC schemes for isolated areas Reconfiguring power lines procedures Fast restoration schemes

13. Todos los derechos reservados para XM S.A E.S.P. Luis Alejandro Camargo S. lcamargo@xm.com.co