Diesel generator to run a fan on a vsd

[AustralIan]

Hi. It turns out running just inverters off of a generator is bad for the generator.

Any tips? Ideally I would like to size my diesel generator to 1.2 * the motor kW rating.

I was thinking maybe put the diesel generator on a vsd as well and link the DC bus, but then how would you start the system with no initial AC power?

Perhaps there is a specific generator to get for such an application? I am not familiar with the different generator options out there, but my understanding is the ones we use at present are the "couple a diesel engine to an AC motor" type, but this will be for new applications.

I would like a solution for around 5kw and for around 100kw, possibly two completely different architectures.

Would an active harmonic filter help / be cost effective?

 

[rawdeal73]

Just put a fan blade on the end of the motor.

 

[DickDV]

VFD's run on generator power all the time. The key is to place a harmonic filter inbetween the generator and the VFD input so the harmonics from the VFD do not reach back to the generator.

The active matrix filter is one of the best for this purpose but you might not need that much filtering. Also, look into ULH (Ultra Low Harmonic) Drives made by ABB and others. They don't generate the input harmonics to begin with so no additional filtering is necessary.

I would expect a little derating on the generator output even with the filters but only a little, maybe 5-7%.

 

[rawdeal73]

Why complicate things? You have a mechanical system (fan) that needs to be controlled... use the generator motor (diesel) to connect directly to the fan. You have speed control... need to go faster, give the diesel more gas... want to go slower - cut the gas flow. You don't need to convert AC to DC to modified sine wave and all that. You save a lot of money on electrical equipment. Wire, filters, transformers, chokes, etc. etc. KISS FTW.

 

[shooter]

5 kW fan will run oke on a 10 kW generator, use a filter as the power control on the generator is very fast.
Obvious you can just put the generator and the fan on the bus, without any control, just give more throttle so the rpm will go up.

100 kW fan is gernerally the same
we use 1 generator for a waterpropellor and change the fuelrack for speed control.
same generator can also run on main bus 60 Hz.

 

[Tom Jenkins]

If you tell your gen set supplier what you are doing they can derate the generator appropriately. The kVA rating is more important than kW. If you bring this up t the supplier and they give you a deer-in-the-headlights look, find a new supplier.