Sarawak Blackout – A cascading failure.

Posted by Pierce in Living | 15 Comments

The whole state of Sarawak plunges into a state of total darkness yesterday. On first instance, we could see activity on Social Media asking if there is a major power failure or not. This follows by scattered info in when the power will come back and at the 3rd hour, some cursing and ranting has go one on Social Media. By midnight, all the fingerpointings starts.

A little bit on why there was that major blackout. Firstly, all our electricity supply are channeled into this big network called a state grid. All the major power generations are done at Bakun, Batang Ai, Sejingkat, TAR, Bintulu, Miri and Mukah, each supplies different amount of loads to the grid,

The supply is then channeled into distribution zone/segments which can be linked and unlinked into the grid. These segment is what that is connecting our premises to the supply.

During the fateful moment, the power frequency drop occurred in one of the Bakun’s supply causing an imbalance to grid. The nearest power generator from Bakun – Kemena Bintulu, was the first to trip to prevent any damages to the generators. This causes a large chunk of supply lost and created a higher demand than supply scenario. Technically, this is called a cascading failure.

An analysis on the sequence of event, Sarawak Energy first reported a trip in the transmission line to the generator in Bintulu. Here is what causes it. The drop of frequency from the power generation from Bakun causes the grid to have poor quality supply. The grid system will automatically rectify the balance from the zone by drawing more load from the area, The reason why Bakun’s line was not detected down in the first place was because the load detection was measured by the Ampere while the grid monitors based in the load in the same bandwidth of 50 Hz. Grid system have lost synchronicity with Bakun and the corrective measure causes all the load to be leveraged on the next to nearest generator – Kemena-Bintulu. Due to the load been higher than what the generator can supply, Bintulu-Kemena line was tripped to prevent damages to the generator.

With Bakun and Bintulu out, there is a shortage of over 1000Mw from the grid which causes load shift to other Power Generation line to trip in the same manner to how Bintulu has tripped. Hence a Cascading failure.

A lot of people blatantly blasting at Sarawak Energy and the Government on this failure.

Now, Let’s take a look at recovery.

In order to fully recover, Each and every one of the generators need to be shutdown and reconnect into the grid one by one. Starting with Batnag Ai, Sejingkat, TAR, Bintulu, Miri and Bakun. Once the grid has supply to it, supply segment is connected into the distribution grid one by one making it a pain staking process. This is done in sequence whereby area nearest to the grid node is restarted first. This is followed by Intermediate and Secondary intermediate and the rest of the sequences.

A grid the size of Sarawak will take between 2-4 hours minimum to restart. This is considering that there is no confounding factor to the scenario. Yesterday was not the best scenario and The problem with Bakun that was serving more than half of the grid load (56.8%) at the time. Even if we load all the rest of the station to the theoretical 100% load/supply ratio will also be insufficient to rectify the load factor. It is only at after 10pm when Bakun has restarted and reconnected into the grid that allows almost complete restorations to the state grid. Prior to Bakun coming online, the grid was split  into two-island with one at the north and another south. The casualty of this is the disconnection of Central grid which supplies to major part of Sibu. This is done to balance the load factors from the North and the South.

The reason why there is a frequency drop is because our grid being a single lined grid. The state grid has no redundancy and load balancing from the point of supply. It seems that this is the lesson for the supplier, in this case, Sarawak Energy and the State Government (owner of Sarawak Energy) to invest into it. Have we got the secondary feed on the grid the drop frequency would not be that significant and will not cause the cascading failure to the state grid, theoretically speaking.

So, before you start blasting them on the inefficiency, please understand how much work they have to do before aiming your arsenal.

*** This is a personal opinion and analysis. Reader discretion is advised.