FOR three consecutive days last week, Wednesday through Friday, both the Luzon and Visayas grids were subjected to the dreaded red and yellow alerts, signifying dangerous shortages of electricity supply at critical times of the day. As I am writing this on Friday afternoon, May 15, it could very well be that the alerts continued into Saturday and Sunday, as well.
Some years are better than others, but we have by now become accustomed to alerts being declared at least a few times during the hot, dry season, usually April and May here in Metro Manila. And we have also become accustomed to the government and the teeming millions losing their damned minds about it, resulting in a great deal of misinformation being spread through traditional and social media. It’s important to try to correct that because fixing the perennial occurrence of power supply alerts is impossible without accurate information.
First of all, let’s refresh everyone’s memory as to what the difference is between a “yellow alert” and a “red alert.” A yellow alert is essentially a warning of an increased risk of an actual power shortage. The National Grid Corp. of the Philippines (NGCP) issues a yellow alert when the contingency reserve, i.e., the generating capacity that is instantly (or at least very quickly) available to meet a sudden increase in demand, or an unexpected drop in supply, falls below the capacity of the largest synchronized generating unit connected to the grid, or power import from a single interconnection, whichever is greater.
Under a yellow alert, there is enough primary supply to meet expected peak demand at any given time, but the reserve power available is less than the biggest source of primary supply. So if there is a problem, such as a plant unexpectedly tripping and going offline, there may be a shortage.
A red alert means the contingency reserve is essentially zero, and the available power is less than the potential peak demand during a particular period. That is obviously not a good situation, and is one in which some customers are going to be without electricity for a time, because there simply isn’t enough to go around. The NGCP and the distributors manage this with “rotating blackouts,” taking particular areas offline for one to two hours on a rotating basis.
The current run of problems began early in the morning of Wednesday, May 13, when, for reasons that have not yet been explained in detail (which is not surprising, as transmission grid and generator connection engineering is not exactly a simple topic), the NGCP’s Tayabas-Ilijan 500-kilovolt (kV) trunk line “tripped.” A line can “trip” for many reasons: a broken insulator, something breaking the line itself, or maybe Bato dela Rosa tripped over it while fleeing from accountability for being the bloodthirsty instrument of state-sponsored terror. After all, the guy’s not exactly what I would call agile.
As I indicated, I have not heard a detailed engineering explanation (yet) about the problem from the NGCP, but because I am intelligent and have more than the average person’s training in these kinds of things, I can make an educated guess as to what happened next. A 500-kV, HVDC (high voltage direct current) line is as big as a line gets on a transmission grid, so a fault that causes it to trip — meaning that the equipment detected some kind of problem, and disconnected the line automatically to prevent catastrophic damage to it — is a serious problem. The immediate problem is that all of the electricity being carried by that line at the time is instantly dumped onto other connected lines; in this case, on Wednesday morning, that was the 500-kV Tayabas-Dasmariñas line. The sudden influx of power on this line vastly exceeded its capacity, so to save it from being damaged, the system tripped this line, as well.
This would set up a cascade to power plants that were online and connected to either of those two main lines at the time, because the power they were producing would have nowhere to go. Thus, their automatic systems would disconnect them to prevent damage to their generation or connection equipment. The main plant affected in this manner was the 2,000-megawatt (MW) Ilijan Gas Plant, but there were others, as well. So, in a very short period, which may have only been 15 to 20 seconds, several thousand MW of supply disappeared from the Luzon grid. This ended up also affecting the Visayas grid, because apart from supply that was unavailable due to several power plants being down for maintenance — something that is totally normal at this time of the year — the supply deficit in Luzon meant that power could not be exported from Luzon to the Visayas to help boost the latter’s supply.
Even though the NGCP identified the original fault on the Tayabas-Ilijan line fairly quickly, and had both it and the Tayabas-Dasmariñas lines restored within hours, the reasons for the nagging supply problems did not instantly go away. Connecting a power plant to the grid is not a simple process wherein one simply flips a switch. To keep the grid stable, the power plant coming online needs to provide power at the correct voltage and frequency in order to avoid another “trip” somewhere in the system. This process can take hours, and sometimes days; it is an exacting process wherein two or three variables have to be managed at the same time, and it is not easy. Ordinary people will complain about, “Why can’t the NGCP just turn the power on?” and all I can say to that is, having seen the process firsthand, including being allowed to close a 50,000 kVa (kilovolt-ampere) breaker on a main power plant-to-grid connection (under close supervision, of course) once just for the “life experience,” I would invite anyone to try to “switch on” a power plant on their own, and see how that goes.
Although this is not a “part one-part two” kind of column, I have a lot more to say on this subject. I will take up some other aspects of the “yellow and red alert” issue in my columns next week, beginning on Tuesday.
ben.kritz@manilatimes.net
Bluesky: @benkritz.bsky.social
Website: www.badmannersgunclub.com
