Linking Two or More Electrical Power Generator Together

Well I designed and built a couple of units to do this, but I dont think a 11kV 2MVA system using 400V generators is what your looking for.

You will need to supply more information about your generators such as size and sophistication of the engine governors and voltage regulators. The concept is basically easy, the results devastating and life threatening if not fully understood and attempted by laypeople.

What is needed:

1) Voltage

2) Single or 3 phase

3) Type of engine

4) Type of engine governor

5) Type of voltage regulator

6) Size of each generator

7) Pitch wind of each generator (I doubt eve the manufactuerer will know this without a lengthy look)

Assuming straight forward AC synchronous generators:

Rules:

A) If the frequency doesn't match, they will never sync, and any attempt to sync will damage the generator and perhaps the engines (and . . . . ahemmm . . the foundation bolts of a 6 Megawatt unit . . . you may be wondering how I know this)

B) If they do sync, and the individual engine governors do not have the same droop response, the power will be imbalanced between the two and likely damage one generator or engine

C) If the voltage is different, they will sync, but there will be a huge protest equal to the size of voltage difference, including damage to the equipment

D) If the voltage regulator droop if difefrent after they sync, VARs will cycle between the units raising the temperature of the generator windings

E) If the phase angles do not match within about 5* as you sync them together, see (A) above.

F) If the pitch winds are different, there may be current flow on the neutrals (assuming these are 3 phase "Wye" connected generators)

If you do not understand 95% of this mail, do not attempt this regardless of advice you receive here. I design power generation systems for a living, and this is very easy stuff to do without automation as long as you TOTALLY understand how to do it and can measure results with simple techniques and common instruments after they are paralleled. Example: I can 'show' you how to measure speed droop of each engine governor, even if the engines and generator are different sizes, with a volt meter across the tie breaker regarding the phase angle relationship of no load to full load (speed droop response) . . . . but if this sounds mysterious, then we have a long way to go. Lots of opportunites to become injured ! Not worth it.

George

The process you are looking at is called parallel operation or sinchronisation of generators,what you need is sinchronisiation panel.Wood word manafactures most of the components required including engine Governers.You need a Qualified electrical contrator to intigrate the woodword components along with engine manafacturers advice assemble the Sinchronisation panel.recently woodword has compleated sinchronisation of 16 generators of diffrent ratings and lot of flexibality and option.you alone cannot exicute this task

I remember that we did this with 3 light bulbs.

Connected over the switch that would connect the generator to the grid.

When the lights were out we assumed that the conditions were ok to enable the switch.

Don't forget to mach the voltage firstly.

It is a manual method and needs to be done very accurate.

Lamp method is out dated and i dont think any where is in use?Tkae the advice of Mr.Petropower Parallel operation of generators is not field where Techonology can be transfered through internet.

You are right, that is how we did it in the previous century.

But if you need to do it and don't have other tools than a DMM it could be handy. (or just to have a confirmation)

There must be plenty of suppliers that can sell automated systems.

Hope the OP doesn't mind my side question here. This question has come up a couple of times and I never paid much attention, but now my curiousity has been pricked.

Assuming I have two little 5HP gas generators; they are older so they were never designed to be run in parallel with another. I was thinking that even once you got them in phase and closed a switch you would need some way to make sure the engines continue to run at the same frequency and stay in phase. Unless I'm missing it here, Gwen you are saying that once you close the switch the AC line would keep them inphase as if on slowed down it would stop generating as much power and should self regulate to stay in phase?

you need to match a host of parameters like KW,KVAR sharig,friquencys ,engine governer droop etc for smooth parallel operation other wise your generators would be runing with a host of problems one i have come across is circulating currents leading to over heating of alternators and alternator burnouts, some times if you dont pay attention to minute datils it may lead to fire and fatal accidents its better to consult a qualified consultant and proceed.

A typical AC generator is somehow the same as a synchro AC engine.

It is indeed so that as long as they are coupled together they will run at the same speed. There are limits: when you would overpower the generator so that it is not able to give its power to the grid it would start jumping phases. that is also why you need to fix the machine (it starts dancing). Never try this (it can explode).

When the engine would give to little energy to overcome the losses the generator would start acting like a motor and drive the engine. (like in your car when you brake on the engine) Again there are limits: asking to much power from the generator-engine makes it starting to dance.

You can measure the power given/absorbed by a synchro machine by measuring the phase between the rotor and the AC field. In a zero power situation (no deliverance or absorption) the phase difference is 0 (the moment that you will switch in or out the gen-set)

When the rotor is before the field: the machine is acting as a generator. The rotor after the field is an engine. The dancing starts when the phase shift would be more than 90°.

There is no way that your little machine will have a different speed than the grid. (there is a way to do this but let's keep it realistic)

It happens more than once: a gen-set runs out of fuel and the generator starts driving the engine. Until something breaks, then oops we should have bought that little protection of $100,-, but my accountant said that it was not needed.

The light bulb method of manual synchronization of gens is still very much in use. Currently we have a 11.2 meg (8 de-rated 2meg units) that have to be synced in one at a time, but they do have Woodward load sharing modules. The other two plants we have here have just been upgraded to automatic with load shed. :-)

We also have several 800kw setups (2 400kw units) that use completely manual controls. Very easy to use, but if you don't know what your doing when you close the tie breaker you will send parts flying. I haven't done it personally, but I have had to clean up the after math and I have shut down a plant and scared the "beep" out of myself just to find out someone hooked the sync scope up to the wrong phase during repairs.

When it comes to synchronizing gens, either know what you are doing or pay someone who does. It is cheaper in the long run.

Happy learning,

Pwr Gen

'When the lights were out we assumed that the conditions were ok to enable the switch.'

How long did it take to assume that lights out also may mean blown bulbs?

George; send me your e-mail. I may need your professionsal services soon.

jhsbusiness@yahoo.com

I just read about a VFT (variable frequency transformer) developed by GE for connection of two power grids. If your generators are large enough to warrant such an investment, it may be worth looking into. If they're not, then maybe you could use the technology to build your own.

Check out http://www.gepower.com/prod_serv/products/transformers_vft/en/variable_frequency.htm

I rep a company called Preon Power and we do what you are asking but we go a couple steps farther, we combine power from multiple micro turbine generators with one diesel genset, that way we have a large kw output and have the the diesel to handle the high inrush for running electric motors. Matching up two or more generators is a very common practice in the coal bed methane business in wyoming.

If you have any questions you can contact me.

bob delong

bob.bcsales@hotmail.com

Two like Honda EU series generators can be linked in parallel to increase available wattage through the generator outlets.

http://www.hondapowerequipment.com/gensup.asp

There was a recent Blog on CR4 on just this subject, it was started with a talk about electricity generating windmills and how to sync them to the national grid.....

What goes around, comes around......

I Also just read about Honda generators which can be connected together by use of inverter technology at http://www.hondapowerequipment.com/gensup.asp

Additionally, generators may be physically connected to the same shaft and timed to match phases, if they are perfectly matched in impedance. Additional power from gasoline engines can be added via fluid-filled torque converters.

If generators are not matched, generators connected on the same shaft for phase matching may be matched in voltage by adding a field-controlled generator, gas engine, torque converter, and control electronics to adjust the field current of the slave as a function of the master voltage.

In the big scheme of things, I wouldn't try it. It's too easy to split circuits in a breaker panel, if that's your application. If it's a single load, you'd be better off buying a larger generator.