Wind stories: Open source electronics for small wind turbines are on their way ! (Tripalium & Aleea, France)

Tripalium and Aleea Electronics Workshop (3 days)

The associations Tripalium (a Wind Empowerment member in France) and ALEEA (Atelier Libre d’Électronique pour l’Énergie Auto-produite) met from June 12 to 14, 2020 in Lîle (Vieillevigne, near Toulouse) for a session of exchanges on open source electronics for small wind turbines.

For the past 5 years the association Tripalium has been working to develop electronics to control the energy production chain from A to Z, from wind turbines to energy use. The association ALEEA is also working in this sense with the development of open source elementary power bricks to allow compatibility between the different systems.

On the conference program: installation of a small wind electronics test site, a presentation and exchange on current projects, a mini-hackaton and reflection on the how-tos of working together on joint projets.

Exchanges on open source projects

  • Windlogger : A datalogger (measurement station) designed for wind and electrical power measurement (project link)

Summary : The hardware part has been functional since 2018, the data is exported correctly to an SD card or via Wi-fi / GPRS. However, until now, an application was missing to centralize the data and allow online monitoring and visualization of the measurements by its users.

Advances : Anik, at the end of her engineering internship at Ti’éole, started developing the Windviewer (project link) application in March. The current phase is in the design of a database. A rich “brain storming” session between the different members of the two associations enabled quite a bit of progress in the design of the database, promising!

 

  • OSWACC : A temperature compensated analog battery charge controller (project link)

Summary : In 2016 Tripalium, Ti’éole and Wind Empowerment financed 2016 the launch of a project to design an analog battery charge regulator to protect the batteries of an isolated wind turbine installation. The project was taken up again in 2018 by Ti’éole to improve its robustness and its precision then presented at the Wind Empowerment WE2018 in Chennai, India. The conference was an opportunity to supply regulators to the various members of Wind Empowerment for a global test campaign. For more than a year, several regulators have been under test and have given good results. It seems that this version of the regulator is stable and robust.

Advances : Some improvements are planned, including, among other things, more robust packaging, surface-mounted components, a new calibration tool, optimization of the power circuit and power supply. The list of improvements and calls for contributions are summarized on the project’s (gitlab page). The working session allowed exchanges between different electronic enthusiasts to orient the design choices

 

  • OwnTech: A multifunction power brick (DC-AC, AC-DC, DC-DC) to bridge the gap between different systems, drive motors, build micro grids. (project link)

Summary : This somewhat crazy research project coordinated by an associate professor at the CNRS (Centre National de la Recherche Scientifique) aims to achieve what they call an “omniverser”, an open source power converter aimed at roughly converting “everything to everything” over a wide range of voltages and currents. After winning a competition at the CNRS, project members carried out experiments in partnership with universities in Greece (NTUA) and Scotland (Strathclyde) to explore the different applications of the inverters.

Advances : The power electronics structure used is a solid state transformer (SST). The challenge is to make compatible a 12Vdc connection with a 400V three-phase network, typically used for motor control, and the home grid. A 400V three-phase SST compatible structure takes the sillicium components within the limits of their operating range and involves passing over other substrates such as SiC, complicating their dimensioning. An alternative would be to use three single-phase SST legs, which poses problems of galvanic isolation between the earthed neutral of the household grid and the ground of the DC network, which should also be earthed. The choice of structure should be made in the coming months.

A project for an analog inverter, being developed by ALEEA, is also underway but the technology and development was not explored by the group due to lack of time (we should plan a week for the next meeting!)

 

Test site installation 

A 24V 1m80 Piggott wind turbine was installed on a 12m mast to supply electricity to a cabin selling drinks and crepes on the edge of the canal du midi (welcoming among others, cyclists, hikers, etc). An open source battery charge regulator (OSWACC) was installed to test its proper functioning and robustness. A windlogger is also in the process of being installed to measure the electrical installation and will make it possible to collect data from the system (wind speed and direction, energy going to the batteries, energy going to the cabin, battery charge threshold, etc.). A OwnTech DC-DC converter will be used to transform the 24Vdc current from the wind system to 12Vdc for the cabin’s 12V loads and 12V inverter.

In conclusion, the three days, rich in contacts and exchanges allowed the two associations to initiate the construction of synergies around free electronics projects for self-made energy. A new meeting is already in the works for October, more information to come…

Adrien Prevost

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