Island Mode Operation

I'm sorry but this sounds like an unrealistic question. 15% of your power generation capability goes to running the power plant that has a total load of 55% capacity. Then suddenly, all at once and unexpectedly faster than operators can anticipate, a single 20% load gets added to make the load to make 75% of capacity. You think this prohibits a coal/steam power plant from operating in island mode. Well when any power plant encounters a change in loading greater than the reserve capacity, thus a load change that can damage equipment, then relays are supposed to protect the infrastructure (generator, transformer, cables). If clueless operators forget to stoke the fires prior to the morning surge in demand then yes, ESO should demonstrate the deficiency of the operators.

I think that you should hire someone who has experience with the dynamics of steam plant operation, the analysis that is required goes far beyond handbook-engineering and/or back of the napkin calculations.

First you have to know whether the plant's control and protective relaying systems will even allow standalone operation, so the answer would be "NO" unless the governor/turbine control/protective relaying systems are specifically designed for such operation.

If they are, then you have to know all the settings including such things as time constants, delays, gains, etc. for the governor, fuel/burner management, steam valve, and excitation control systems, as well as the dynamic characteristics of the T/G and the proposed loads.

Once you have that (and much more) data then you can start doing prefault/postfault transient stability analyses of your system.

Not all units perform well (if at all) when sudden loads are applied. Been there, done that, having performed many highly instrumented live-system tests to verify that the computer models accurately reflected what really happens in real life.

btw- Island operation usually refers to a grid connected unit that suddenly finds itself tripped from the rest of the grid. Is that the case here or is the unit designed for supplying only local load with its own frequency reference source?

i agree with what you said.the unit is basically designed for operation in grid connected mode.however the national grid is unstable and usually trips.we do not want our coal unit to trip and want it to operate in off.grid or isolated mode to supply our local load. now i think that coal based units cannot operate in isolated/off grid mode

Then how did the first such unit ever manage to operate at all?

No responder to any thread needs to prove anything.

There is a magic feature of the internet that can be used by the uninformed to gather limited knowledge about most any subject.

It is also very fast, compared to wasting time asking anonymous strangers to provide the information that you seek. That is just half fast.

It's called a search engine.

What is meant by the island mode operation of a power plant? - Quora

sland mode operation feature - Decentralized Energy

Island operation | DEIF

Improving the Flexibility of Coal-Fired Power Plants - Power Engineering

Don't be half fast. Do some research for yourself!

I agree. There comes a time when personal safety should overrule the free dispensation of knowledge not possessed by the requester.

Especially to those who continually display a lack of competence.

they used to build steam accumulators, back in the olden days, rather large ones.

This upset scenario doesn't sound like a show stopper, voltage is a function of field excitation, not necessarily rotational speed, most load devices have a pretty wide frequency tolerance, so might not be as bad as you think. Usually not bad enough to warrant stopping the whole show.

Not much reason to trip the generator on low voltage or frequency, except when that shows as a precursor of unrecoverable power system collapse or external fault exceeding the current rating of the windings, long term or short term.

<...what you guys think?...> is irrelevant.

This is a question of design. And the only CR4 subscriber that can see the original design documentation is the Original Poster.

So:

• Why is low frequency or low voltage a trip-worthy problem in <...Island Mode...>?
• Is there a high frequency or high voltage trip?
• What are the current trip settings during <...Island Mode...> operation, and are these realistic/problematic? Why?
• If the thing trips, then 30MW goes off-line; of what consequence is this for the plant?
• What happens when the unit becomes disconnected from the local grid and an 8MW load gets applied to it - don't the commissioning records say at all? What operational experience is there of this scenario?
• Were these scenarios ever written into the original Commissioning Plan document for testing? If not, then why not?

The documentation that answers these questions cannot be seen from here...

Dear Mr.coolyar,

The details given by you is insufficient.

Before going to the subject, the load increase resulting in higher steam demand involves several parameters. As we all know, that it depends upon:

1. The Heat Release Rate in the Furnace and its control.

2. The Degree of Pulvarisation of Coal.

3. The Percentage Constituent of the Pulvarised Coal i.e., Percentage of different particle size in Microns or MM.

4. The Air-Fuel Ratio.

5. The Moisture in the Coal.

6. The calorific Value of Coal.

7. Actual Non-Combustibles in the Coal

8. Less Furnace Temp. on account of higher Excess Air.

9. Less Temp. of Pre-Heated Air.

10. Less Feed Water Temp. entering the Boiler Drum.

11. Higher percentage of combustible particles in the ash (partly relating to Heat Release)

12. Higher percentage of Carbon-Monoxide than permissible.

13. Insufficient Draught, actual draught – not asper manufacturers recommendation.

14. Excessive gap ID Fan Impeller guide cone where lot of recirculation takes place, thus reducing the quantity of actual capacity of Flue Gas sent out of Boiler.

15. Excessive gap of FD Fan Impeller guide cone where lot of recirculation takes place, thus reducing the quantity or actual capacity of air pumped in to the Boiler.

16. Excessive gap of SA Fan Impeller guide cone where lot of recirculation takes place, thus reducing the quantity or actual capacity of air pumped in to the Furnace.

17. Higher slippage of ID Fan, FD Fan Belt, reducing the capacity of the Fans, thus less air.

You have to furnish the following details.

1. Do you have a bunker at the top – to store pulvarised coal for a minimum of 8 to 10 Minutes of duration for full capacity of Power Generation.

2. What is the Excess Air% used. Is it asper Boiler Manufacturer’s Manual.

3. What is the analysis of CO2 % and O2% and CO% in the Flue Gas.

4. What is the % of combustibles in the Ash Collected.

5. What is the Percentage of Non-Combustibles in the Coal.

6. What is the Calorific value of the Coal.? Is it with in the limits specified.

7. What is the Moisture% of Coal

8. What is your Grid Voltage.

9. What is the pulvarised coal particle sizes in Percentage.

Regarding Tripping due to Grid related issues – the Transmission Line Voltage has considerable impact for stable operation. Higher the Voltage, more the stability.

DHAYANANDHAN.S