Ref. Ares(2021)4296942 - 01/07/2021
TENERIFE BLACK-OUT
July, 15th 2020
Electricity Coordination Group
September, 22th 2020
Tenerife Characteristics
Isolated system (planned interconnection with La Gomera island)
• Central dispatching model.
• Low network mesh and concentrated generation (orography conditions).
• Reserve levels (according to Operation Procedures): 97,98 MW to rump-up & 189 MW to rump-down.
Installed capacity (1225 MW)
• Thermal capacity 918 MW: Granadilla (693 MW), Candelaria (139 MW), Arona (43MW), Guía de Isora (43MW).
• Renewable capacity 307 MW: 196 MW (eolic) + 107 MW (photovoltaic)
Black-Out Incident (1/3)
Before the incident
• Demand:
424 MW
• Generation mix:
15% RES (wind/solar)
85% Thermal (steam/diesel/combined-cycle).
• Granadilla Total Output:
339 MW (94% demand)
Granadilla CC-I: Gas 3 + Vapour 3:
53,2 MW + 31,0 MW (84,2 MW)
Granadilla CC-II: Gas 5 + Vapour 4:
52,5 MW + 26,0 MW (78,5 MW)
Incident timeline
• 09:41 Granadilla Gas 3 is accidentally manually triggered. Vapour 3 triggers.
Frequency drops to 48,897 Hz.
• +5,2s Granadilla Gas 5 rumps-up to its maximum output, and trips due to high temperature gradient of
exhaust gases.
Frequency drops to 48,066 Hz automatic under-frequency control scheme activates.
• +2m5s Granadilla Vapour 4 triggers .
The performance of the automatic under-frequency control scheme was not enough to compensate the progressive
generation loss.
• 09:44 Frequency drops, all generation groups trigger, the black-out occurs.
• Supply interruption:
424 MW
• Estimated Non Supplied Energy:
1.913 MWh
• Clients affected:
over 515.000
Black-Out Incident (2/3)
Incident timeline
Generation and frequency variation during incident:
Black-Out Incident (3/3)
Incident timeline
Frequency variation during incident:
Restoration Plan (1/2)
Tenerife system restoration plan
1. Connection of power sources with black start and island operation capabilities: Granadilla &
Candelaria gas turbines.
2. Coupling of Granadilla & Candelaria gas turbines.
3. Bottom-up demand re-energisation in a controlled and safe way.
4. Supply re-energisation is completed at 16:44, once there is enough generation to supply all the
demand.
Progressive generation coupling
Restoration Plan (2/2)
Progressive supply re-energisation
Time
% Supply re-energised
10:45
4% (20.688 clients)
11:30
10 % (51.521 clients)
12:30
20 % (103.042 clients)
13:20
40 % (206.085 clients)
14:40
50 % (257.605 clients)
15:15
60 % (309.127 clients)
15:40
80 % (412.169 clients)
16:45
100 % (515.211 clients)
Actual Supply vs Forecasted Supply
Assesment and Conclusions (1/2)
On Wednesday, July 15th, 2020, Tenerife suffered an electrical blackout, starting at 09:41.
All substations that feed the distribution network had tension at 12:00, and full supply re-
energization occurred at 16:44.
Investigation and determination of liabilities on-going by regional authorities.
Difficulties
• Tenerife is an isolated system, with low meshed grid.
• Thermal generation is mainly concentrated in 2 sites.
Achievements
• Effectiveness of Restoration Plan
• Proper functioning of the control and command centers of the TSO & DSO.
Assesment and Conclusions (2/2)
Conclusions
• Interconnection is essential to ensure
operational security and to facilitate system
restoration.
• Grid development and reinforcement is key to
achieve
a
more
meshed
and
robust
transmission system. Storage systems would
strengthen the transmission system and the
system operation, specially regarding RES
i mplementation target (NECP 2030).
• Improve reliability of generation groups, trying to avoid undesired triggers and to speed up black start processes.
• TSO/DSOs should review, update & guarantee the proper implementation and function of the automatic under-
frequency control scheme and other emergency plans.
Thank you for your attention