A Guest Post by: Jase Kuriakose from the Centre for Alternative Technology.
Renewable Micro Grid
The CAT micro grid works through a collection of micro generation technologies grouped together through intelligent controllers, energy storage system and connected through our export system (G59) to the utility grid. The micro technologies used in the system are all from renewable sources including sun, wind, hydro and biomass. If the national grid fails then the micro grid recognizes it and switches itself off automatically keeps continuing to generate power from our renewable generators and provide power to the precision mains load.
CAT currently produces 21.5 kW of energy from photo voltaic roofs, 3.5 kW and 4 kW from hydro energy and 600 W proven wind turbine connected to the micro grid. More energy generators can be connected in the future. The micro grid can provide 30 kW for 3 hours if there is no grid and no generation at all (no wind, sun and water). If there is some generation then it will provide power for more time.
The CAT micro grid system works differently from conventional systems of batteries and inverters. Here the generators are not charging the batteries all the time. It delivers electricity directly to the load or to the grid. The batteries will normally be in sleep mode and will only activate in emergency situations when it is really needed. The micro grid has the facility to prioritize the load. In normal conditions it gives power to all the precision main loads, then to raw mains and then excess power is exported to the utility grid. If there is no energy is no energy generation and no grid for a long time it will switch off the precision main loads first. But it will continue to give power to the emergency lights and alarms.
There are other examples of island generation systems for example in the isle of Eigg (Scotland) that has 3 renewables energy sources integrated together but they are not connected to main utility grid. There is also a micro grid systems run by Woking council but using only one or two technologies connected together such as with PV and gas CHP. This is the first of its kind in UK integrating 3 renewable technologies and that is connected to the micro grid.
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Jase Kuriakose is an engineer at the Centre for Alternative Technology in Wales. CAT has been working for over 35 years to find practical and sustainable solutions to some of the big challenges we face today such as climate change. www.cat.org.uk
very informative and interesting article, we have been looking for something similiar ourselves
thanks