Generator Response and Tripping

I probably have more questions than answers, but hopefully some ideas may emerge.... In no particular order:

1. The four already running units responded to the final sudden drop-out of Sual 1, for varying lengths of time.

2. During the Sual 1 "brownout" period (11:03:19 - 11:03:46), San Roque and Sual 2 took on load in good proportion to the wavering of Sual 1.

3. I'm guessing that Sta. Rita 40 and Ilijan B2 were already running at full capacity. After the brief bump upward, they returned within about 10 seconds to their former loadings.

4. San Roque helped out well for about 25 seconds, but then dropped below 90 MW; I'm curious why.

5. Over the whole 2 minutes (11:03:19 - 11:05:16) of this incident, Sual 2's curve conforms best to a scaled inversion of the overall system frequency curve. I would say this plant "saved the day."

6. Did Magat have to be manually started or something? It didn't get into the act for over a minute, and even then ramped up rather slowly in comparison.

7. "Transient response" is a correct term; the 4 running plants seem to have done well in that respect, though 2 of them not for long. (Note 3.) "Ramp-up" would be another good term.

8. Do you know yet why Sual 1 bombed out? I hope it was some little control thing, not an expensive breakdown.

9. What are these various plants? Hydro, steam turbine, nukes in your location?

10. One factor that may be involved in each case is the rotational inertia of the equipment, and how quickly the flow rates of water, steam, or neutron flux can be increased. (Opening valves or gates, feeding oil or coal faster, withdrawing control rods.

11. Interesting question, and best of luck getting to the bottom of this. I hope something in here may be helpful.

12. Welcome to CR4!

thanks for the reply tornado!

6. Did Magat have to be manually started or something? It didn't get into the act for over a minute, and even then ramped up rather slowly in comparison

yes sir, it was manually dispatched, and it was the scheduled spinning reserve provider for that hour. it did delivered its scheduled 55MW for spinning...

8. Do you know yet why Sual 1 bombed out? I hope it was some little control thing, not an expensive breakdown.

the tripping was due to to boiler feed pump trouble, and not shown in the graph was calaca which also tripped due to under frequency.

9. What are these various plants?

sual- coal fired, magat and san roque - hydro, while ilijan and sta rita are combined cycle plants.

the tripping actuated the automatic load dropping scheme of our grid... i have to prepare a report whenever ALD occurs to the grid or when there is a loss of at least 100MW to the grid. right now we have very low available reserves the reason why we have a very "shaky grid"

Hi,

When Saul 1 tripped the other generators have to take the load temporarly. The frequency dip is due to loss of generator. A temporary response is called transient response.

Did you have any load shedding or any other control in the generator going on?

Did you have any load shedding or any other control in the generator going on?

yes sir, as i have mentioned on my recent post, ALD(automatic load dropping) occurred to prevent further decay of frequency.

thank you so much for your replies mr johnson and msamad!

followup question:

lately both sual units are responding strangely. as seen in the graph below, whenever the frequency drops, sual units also drop their generation instead of increasing it? do they have a term for this kind of generator behavior? i think they tweak their governor to disable its transient response capability, can you really disable those functions???