The small system for capturing water that has been realized.
One of our company philosophies is to be always on the lookout for technically advanced solutions, thanks to our study and experimentation.
We have created a micro hydroelectric plant, off grid, with particularly advanced technical solutions in every component of the system.
The construction site was a small farm adjacent to a valley called precisely "valley of the mills", where historically there were some milling buildings in the waterfall, which exploited a small mountain stream.
The request in this case was to be able to generate electricity using the water head, in a plant however disconnected from the grid, without then placing and selling energy, practically in complete self-consumption.
After an inspection we noticed:
- A water head, thanks to the presence of two waterfalls, between the location of the intake and the position of the turbine, of 56 meters.
- A variable water flow rate during the year, unfortunately we could use only about 2-3 liters per second with our concession.
The peak production of our Turbine MT-02 (Pelton) is about 1 kW so this model was particularly suitable in this situation, where the potential energy of the water head was between about 1kW - 1.5kW.
The turbine cockpit under construction.
With the indicated data we estimated that we would produce about 600 to 1000 watts with the turbine. The loads however had the need to consume up to 3 kW at certain times, so it was necessary to combine an accumulation system capable of storing the excess production and granting it in the peaks of successive loads, through the inverter.
We have therefore combined a modern 2.5kWh - 48V lithium battery capable of charging and discharging rapidly without loss of life cycles; otherwise we have provided a much larger lead-acid battery pack, and we also had space problems in the technical compartment of the building.
The battery is then charged by the hydroelectric turbine, via a "VarioString" charge controller with MPPT technology from Studer Innotec with a maximum input voltage of 600VDC.
Why did we use a solar regulator for a hydroelectric turbine ...?
Mainly to optimize the technical solutions,
These are the main reasons:
- The turbine had to charge the 48V lithium battery, and not produce directly 230VAC, because its power was lower than the possible loads and because for this purpose it would still have been present a 3kW inverter.
- The turbine would have been, compared to the technical compartment, about 200 meters away, so we would have to put power lines that would have dispersed more energy in the case of low voltage production. It was therefore inconvenient to also generate the 48V for the batteries with the turbine. We then used a high-voltage MPPT, causing the turbine to generate about 190VAC three-phase, which would have been around 260VDC after a rectifier.
- The MPPT controller would be integrated into the Studer system with the possibility of monitoring and monitoring of production
- Finally, the MPPT regulator, thanks to its technology, would have allowed to slightly change the working point, that is the revolutions, of the operation of the turbine, to find the point of maximum production.
We want to reduce inefficiences as little as possible.
Compared to a photovoltaic system, however, a turbine behaves differently: in fact the current / voltage curve is obviously different, in particular because when the load is not applied to the turbine, this tends to "run away", i.e. increasing the rotational speed and the voltage of the alternator.
The alternator of our turbine is a 6-pole magnets permaments, with winding made to the voltage necessary for our project.
In fact, to respect the maximum parameters of the regulator, and to prevent the turbine from "running away" in case the regulator had not to charge the batteries, we have provided an ABB WIND interface for wind generator that regulates the three-phase voltage and in case of exceeding a Safety voltage threshold sends excess energy into an external ballast resistor.
Finally, we have combined the turbine with a modern and simple PLC touch screen control system that controls the main water supply, closing the water in case the batteries are fully charged and no longer producing energy.
The same control system also monitors the pressure of the pipeline, closing the water in the event of a drop in pressure (ie, any drops in flow) and also the revolutions of the turbine, closing water in the event of an escape or increased turbine speed beyond our safety thresholds.
We have also applied to the turbine a variable motorized plug injector, controlled analogically by our PLC, to precisely regulate the flow rate and therefore the turbine output, between 400 and 1000 Watts.
We have made a small reality independent, with a production of about 20kWh daily, more than enough for a family.
Now he has only the fun of keeping the torrents clean!