The latest unscheduled blackout could be attributed to lightning that struck a portion of the transmission infrastructure of the National Grid Corporation of the Philippines (NGCP).
The NGCP is set to issue a statement this week regarding the incident.
It was learned that there were signs of burns on the transmission facilities inspected after the tripping of the 138-kilovolt Ubay-Corella line on December 27.
This led to an initial theory that a strike of lightning caused it.
The 138-kilovolt Ubay-Corella line momentarily tripped from 1:30-1:40 pm, causing power interruption in entire Bohol.
However, Betty Martinez, spokesperson of NGCP-Visayas, explained that it would take a few minutes before power reaches to the last feeder for restoration.
After the power interruption, the Bohol station of NGCP sent linemen to trace the cause of the tripping of the 138-kilovolt Ubay-Corella line.
The following day linemen continued patrolling to look for the cause of the tripping although there was already an unconfirmed report reaching their end that it could be lightning.
NGCP engineers looked for physical signs and electronic registrations such as in the current or voltage to check if it was indeed lightning that caused the tripping of the 138-kilovolt Ubay-Corella line.
Three previous power shutdown affecting Bohol just within December had been attributed to hitches in Leyte side of the grid.
The prior blackout was on December 17 and the first was on December 3 that was immediately followed by another round a few hours after resumption of power.
The power interruptions on December 4, December 17 and December 27 were all unscheduled.
The December 3 was scheduled in relation to line upgrading activity as a second line, or Line 2, has been added to the Leyte-Bohol grid that supplies electricity to Bohol through submarine cables.
The December 17 power shutdown actually came in two installments- -first, at 9:56-10:31 a.m. and at 11:18 a.m. to 6:00 pm.
NGCP attributed it to the tripping of Ormoc-Maasin 138kV Line 2 as winds affected Leyte.
NGCP had earlier explained that the common cause of unscheduled power interruptions is “vegetation” such as coconut fronds, branches of trees, or any even banana leaves touching the transmission lines. This causes load interruptions.
The first and only scheduled power shutdown for December 2016 was on December 3 that was supposedly for 13 hours only- -from 4:00 a.m. to 5:00 pm- -stretched to 20 hours and a half and NGCP managed to restore power only at 12:27 a.m. on December 4, attributing it to bad weather that made it difficult for the NGCP linemen and engineers to undertake the procedure.
An unscheduled power interruption affecting the entire Bohol followed at 1:21 p.m. and NGCP restored power at 2:02 p.m., attributing it to another tripping of the 138kV Ormoc-Maasin Line 2.
The “bad weather” factor in Leyte side was among the priority issues that Gov. Edgar Chatto sought to address when he assumed his first term in 2010 in the subject on power supply.
Chatto then mobilized teams to start researching on the possibility of establishing Bohol’s own power supply, inland.
When Bohol experienced total power shutdown from Leyte for over a month after Supertyphoon Yolanda hit Leyte, the governor drew multi-sector support.
After several consultations with experts, Chatto issued an executive order in January 2014, creating the Bohol Energy Development Advisory Group (BEDAG).
BEDAG initiated the formulation of the Bohol Island Power Development Plan (BIPDP) with the assistance from the United States Agency for International Development-Advancing Philippine Competitiveness (USAID-COMPETE) Project.
The BIPDP, a long-term energy plan for the province, is aimed at ensuring security of supply- -that is, available when needed; ensuring reliability and resiliency that entails climate-proofing of supply; and ensuring affordability.
BEDAG “is an institutional mechanism for planning, implementing, and monitoring of power development initiatives in Bohol”.
It is “a multi-sector group composed of various representatives from the Local Government Unit, Private Sector, Academia, the NGCP, and the three local distribution utilities”.
On December 21, the Provincial Development Council (PDC) presented the power supply projects given consideration by the Regional Development Council.
The projects include the Cebu-Negros CNP 230 kV Backbone Project–Stage 3 is targeted in December 2020; CNP 230 kV Backbone Project-Stage 2 in December 2018; Cebu-Lapulapu transmission line in September 2017; Cebu-Bohol Inter-connection in February 2021; Tagbilaran substation in December 2020; and feasibility study (FS) on Visayas-Mindanao Interconnection.