Initial Investigation Report Submitted on Nationwide Power Outage

COLOMBO(News 1st): The National System Operator Company has submitted its initial investigation report to the Public Utilities Commission of Sri Lanka (PUCSL) regarding the nationwide power outage that occurred on the 17th.

The report reveals that the power generation at Unit 1 of the Laxapana Power Station first experienced a sudden drop. As a result, its power generation capacity plummeted from 187 MW to 5 MW within a span of 450 milliseconds.

Consequently, the frequency of the national power grid dropped from 49.906 Hz to 48.75 Hz within 2 seconds.

Due to this situation, all five stages of the Under-Frequency Load Shedding (UFLS) protection system designed to safeguard the power grid were triggered.

Ultimately, power generation at power stations ceased, and the island-wide national grid collapse began at approximately 11:43 AM on the 17th.

Following the onset of the grid collapse, generating units at several power stations tripped and shut down, including:

Multiple units of the Laxapana Power Station

New Laxapana Power Station

Polpitiya Power Station

Victoria Power Station

Samanalawewa Power Station

Old Laxapana Power Station

Upper Kotmale Power Station

Kukuleganga Power Station

The report states that the generating units at these power plants automatically tripped due to various system protection mechanisms.

After the system collapse, restoration work was initiated across four main subsystem networks:

Mahaweli Power System

Laxapana Power System

Samanala and Southern Power System

Colombo Power System

According to the report, the first electrical substation was re-energized at 12:37 PM, and the final substation was successfully restored by 4:58 PM. It took 5 hours and 15 minutes to fully restore the entire national power transmission grid.

During the power restoration process, technical issues arose at several power plants, delaying their reconnection to the grid:

A turning gear issue at the Yugadanavi Power Plant

Start-up process issues at the Sobadanavi Power Plant

Issues with the standby diesel generators at the naphtha-powered Kelanitissa Combined Cycle Power Plant

Additional time required for system recovery at the diesel-fired Kelanitissa Combined Cycle Power Plant

When the grid frequency drops, the Under-Frequency Load Shedding mechanism automatically trips power supplies to protect the overall grid by managing demand. The report notes that all five stages of this protective mechanism were activated during this incident, disconnecting 39.6% of the total electricity load.