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Topic Title: Small scale remote power using 3 generators.
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Created On: 05 January 2010 03:57 AM
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 05 January 2010 03:57 AM
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Pat Lucey

Posts: 29
Joined: 18 May 2006

Dear all I would like some ideas for making a 3 genset system for a remote off grid lodge. The loads can be from 5 Kw or less to 100 Kw max. ( 240 V / 120V single phase.) The idea is to have three gensets which will automatically do their thing and take care of the varying load demands. I have done some genset paralleling but it was awhile ago on much bigger stuff.. I am not upto date with what is about in terms of switchgear and PLC controllers. The generators and governers I understand. Its the control system I need help with.
Thanks for any tips or links.

Cheers Pat.
 05 January 2010 06:02 AM
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Posts: 60
Joined: 02 February 2009

Hi Pat,

I would suggest you draw yourself a graph of the load from 0-100Kw and then add the block loading of the generators over the graph to determine which and how many generators you are going to run. This then gives your operational logic to be implemented in your generator controller or PLC. At the planning stage you should also consider minimal loading, running the minimum number of generators and what to do if a generator is unavailable. I hope I have interpreted your question correctly.

 05 January 2010 11:45 PM
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Posts: 225
Joined: 09 September 2002

Hi Pat,

Can I suggest an alternative approach to your challenge. The best efficiency/ lowest cost per kWh with a diesel generator is gained when operating at a high capacity factor, for limited running hours. You could just purchase a diesel generator of between 60 - 100kW and combine this with an inverter/ charger and battery system of ~40kW capable of operating in parallel with your generator. I'm thinking specifically of the Sunny Island Inverters as per this link (I'm assuming that from the voltages you mention that you're in N America)

These inverters include a control system that will start and stop the generator according to parameters that you can programme in. Under light loads (with the battery in a reasonable state of charge) the inverter can provide the power. At higher load levels (pre-settable), or if the battery is becoming discharged, the generator is started and the inverter synchronises with it and transfers the load onto the generator whilst simultaneously using the spare available capacity of the generator to recharge the battery. If the load exceeds the generator rating, the inverter contributes to make up the shortfall.

I've personaly designed systems like this for island communities and can testify to their effectiveness. They have an added advantage in that it's very straightforward to integrate distributed renewable power sources (PV/ wind/ hydro) at any point in the future to give fuel savings. Remote communication capabilities are also available.

These systems also lend themselves to distributed load management, and if spare capacity is available, additional loads such as water or storage heaters can be automatically switched on. The following link gives further system information which may be of interest:

Good luck with your scheme.


 06 January 2010 04:56 AM
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Pat Lucey

Posts: 29
Joined: 18 May 2006

Thanks Al and Jonno. I will take a look at the links. This remote site power system is still being planned. The problem being is that there is changing info from the customer as to what he wants and what is load requirements will be. Certainly the control logic will change as the site gets built.
I have used the Sma inverters in a system with gensets and batteries. There has been a fuel saving of 50 % from the previous set up of a generator 24/7. We did lighting upgrades and got the lodge staff to turn things off etc... They like the quiet when on the batts.! Still more to do with this one but a good start. The batts are being cycled a bit too hard. .
Back to this project they are not too interested in batteries due to the preceived mantaintence requirement. We use Penn batteries for our larger Renewable systems and are less trouble than the gens...
The costs we had today for a complete switchgear and control system seemed high. The stock small diesel gens would have to have electronic governers fitted as there are not availible on these smaller sizes. All this adds up to a costly and complicated system. Not ideal when you long way from anywhere.
We have done a system with two gens and a transfer switch. A load monitor starts and stops each gen and makes the transfer. It works great other than a time delay blackout during switching...
Thought it would be easy and cheaper to do this one with 3 standard gens of different sizes and 2 transfer switches... The load monitor would control the starting and stopping and which gen fed the load. ( Cant get past the blackout thing. ??... ) .

Still looking at things. Will let you know how it goes. Thanks for your thoughts.

Cheers Pat.
 25 February 2010 02:37 PM
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Posts: 1
Joined: 25 February 2010

May be this could be helpfull for your system?
In server room and on remote equipment we use (we internet provider) such device Elgato GSM-rebooter for 6 outlets (220 V). Can control it by SMS or GSM-calling. Every outlet controlled separately On/Off/Reset (Off and after pause - On) + temperature sensor with alarm by SMS, SMS-messages about Power loss and so on.. Usefull stuff! Save time on driving to other part of city for switch reset.

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