Paralleling a Deisel and Turbine
Paralleling a Deisel and Turbine
(OP)
I have a telco client that wants to Parallel a 750kW Deisel and 750kW Turbine. The turbine is existing, and the deisel will be new. A new deisel is cheaper than a new turbine to buy. Clearly we will upgrade the govenor and voltage regulator on the turbine, but can a deisel play nicely with a turbine sharing load? Especially during load chages?
Anyone have some suggestions?
I have paralleled turbines together without problems. I have parralled deisels together without a problem, but not a deisel and a turbine together.
Anyone have some suggestions?
I have paralleled turbines together without problems. I have parralled deisels together without a problem, but not a deisel and a turbine together.






RE: Paralleling a Deisel and Turbine
http://www.basler.com
etc. for more info
RE: Paralleling a Deisel and Turbine
RE: Paralleling a Deisel and Turbine
My main concern is how the two different types of machines will react to load changes, since the turbine is such a stiff source as compared to the deisel.
RE: Paralleling a Deisel and Turbine
Your concerns are justified if the two units are islanded (ie. is this a backup supply?) as during faults they will clearly behave differently.
The load sharing issue can be resolved with the use of a modern controller.
A transient study would be the next move to quantify the system stability during faults and application/loss of loads, however accurate modelling the governors is always a pain with Diesel units, let alone these small turbines. Is your turbine an aero-derivative (i.e. Pratt & Whitney) or industrial (i.e Solar) ?
Regardless of the prime mover response, the two packages will have different moments of interia and this alone requires further review.
Being a TelCo client, a full stability study may be justified for assessment of supply continuity.
Regards,
AusPowEng
RE: Paralleling a Deisel and Turbine
A clarification to my first sentence:
Your concerns are justified if the two units are islanded from the grid (ie. assume this a backup supply rather than co-generation?) as during faults they will clearly behave differently (than when operating in parallel with the grid).
RE: Paralleling a Deisel and Turbine
I have to do some research into stability studies. Any suggested reading?
RE: Paralleling a Deisel and Turbine
RE: Paralleling a Deisel and Turbine
RE: Paralleling a Deisel and Turbine
But I like deisel engines, they are tuff . But, if you have turbines, stay with the same type of system or replace the turbine too with a desiel. Look at the long term cost not just first cost. I believe the life and maintence are longer with turbines, less moving parts.
Look at the long term cost not just first cost.
RE: Paralleling a Deisel and Turbine
This client has many many sites throughout the country. Many turbines and many deisels. In this case, considering first cost will be similar to the whole picture. The turbine is in good operating order, and the cost of a 750kW turbine is much more than an equivelent sized deisel.
RE: Paralleling a Deisel and Turbine
I agree with the concern that numerical modeling of these systems will be difficult. Obviously there are many components that must be considered (machine, prime mover, governor, voltage regulator, exciter, etc). Unless you have software that is known to accurately model the specific equipment, I think it would be unlikely to get meaningful results. CYME's CYMSTAB program includes a number of generator control models. They may be able to provide what is needed.
It is important match the generator electrical characteristics (e.g. impedance, winding pitch, fault decrement), as closely as possible to minimize circulating currents. In a telco application your load is likely to have significant harmonic distortion. This makes matching electical charcteristics more important. Your control system should include automatic VAR sharing (some inexpensive schemes do not).
I assume keeping the machines separate is not an option? If you operate them in parallel and either one fails you loose all your load. Consider keeping them separate (or using automatic load shedding) so if one fails you only loose half the load.
Also see
Thread238-64661
RE: Paralleling a Deisel and Turbine
I hope this helps.
RE: Paralleling a Deisel and Turbine
http://www.turbowinds.com/windiesel.html
etc. for more info
RE: Paralleling a Deisel and Turbine
I have experience paralleling steam, diesel and gas turbine units of vastly differing capacities on one site without any problems whatsoever.
You just have to tweak your control systems properly otherwise the turbine may try to hog the load.
Go for it.
Colin.
RE: Paralleling a Deisel and Turbine
RE: Paralleling a Deisel and Turbine
I am with Cummins Indai and wehave being doing this job all tne time.
One of our major job was paralleling 5 DG sets with 2 x * MW turbines.
I do agree that transient analysis can be helpfull.Pl remmember that for DG alternators the Xd'is very low and hence we need to consider fault level currents.
However with our expereinces it should not be a major problem
Rgds
RE: Paralleling a Deisel and Turbine