Can one synchronize a COGEN with utility without parallelling ? 4

[hmchi]

The utilities in the world usually do not like co-generation systems of their customers to be parallelled to the utility own system. Many simply forbid it. However, when there is a problem and the customer paid to have a 'hot standby' source from the utility, they will allow a source transfer operation.

Obviously we need to switch when the 2 sources are in sync. So is there a way to keep the COGEN in sync with the utility source without actually connect in parallel ?

 

[hmchi]

rbulsara

The machine is 15MW and load is approaching 10MW. It is a textile plant so the load is mostly VFD drives. Yes, very sensitive to undervoltage. Yes, we are looking into segregating loads and perhaps a medium voltage UPS backup for the VFDs [about 5MW], but it is really expensive .. so if we could handle this with sync and fast transfer to utility, it would be a big cost saving not to bother with the UPS.

Static transfer switches only work when you are in phase or nearly in phase [we have the same problem of consistency in sync], and they are also terribly expensive at 6.6kv ..

The plant owner said that they did not initially invest in personnel training thus had more turbine trips than usual, but not out of electrical short circuit faults, etc.

 

[rbulsara]

hmchi:
Thanks for the feedback. Cost all relative. A mishap in a fast transfer can cost dearly too.

Rafiq Bulsara

http://www.srengineersct.com

 

[ScottyUK]

UPS modules for that kind of rating: contact companies like Anton Piller, Eurodiesel, Hitec Power Protection. All can either do a direct MV solution or an LV solution with a step-up transformer. I think GE had a big rotary design too although they might have bought up someone else to acquire the technology. No doubt Rafiq could add a couple more from North America.


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If we learn from our mistakes I'm getting a great education!

 

[rbulsara]

Jon:
Piller and Hitec are the names here. Rotary UPSs are not very popular here more due to misconceptions than anything else and some cost issues.

Although I feel more comfortable with Piller style, which is different than Eurodiesel or Hitec. Those two have similar technology (MG set, clutch and engine).

In this particular case any solution other than utility paralleling is going to cost a small fortune.

Rafiq Bulsara

http://www.srengineersct.com

 

[rhatcher]

hmchi,

I am curious. In most cases when I think of cogeneration, it is when a manufacturer has a byproduct that can be used to produce power. A common example is that many paper mills use the excess steam from the paper making process to run steam turbine generators. What byproduct is used to produce 15MW power at a textile plant? Is it steam or is it something else?

Back to your question....I would guess that the contribution of power (or fault current) from a WTG would be much less that the 15MW generating capacity that your plant has. That may be the difference, from an engineering and an economic standpoint, on whether your utility allows parallel operation.

From a political standpoint, it is sad to say that today the normal engineering criteria of simplicity, economy, and effectiveness are often overlooked in favor of being 'green'.

 

[hmchi]

It is not a garment factory. The outputs are films, yarns and so forth that are the first phase of the textile industry. It is basically a petrochemical plant using steam extensively in the process. They up the pressure to generate before sent to the process.

As for WTG, you should know that Farms these days would aggregate 50 or more WTGs at 2 MW each .. interfacing with utility at 115kv.

The WTG farms are a lot less forgiving then steam turbines and undervoltage conditions can be quite disruptive to the WTGs .. Wind generation output can be quite varied from day to night, day to next day .. which normally utility would cite as 'unreliable' .. utilities bend over backwards to cater to the wind farm people. Yes, it is political..

COGEN could be green too .. If the generation increases the efficient use of fuel to energy transformation, it is no less worthwhile than Wind Farms ..

 

[slavag]

Hi.
hmchi, try explain to your utilities, that cogeneration good for them too. See, your case is classical case of cogeneration, becouse you need steam for process too.
But w/o connection to utilities you are very, very weak source.