At the Kville site, we were faced with capacitive cables* connecting the wind mills to the site’s substation (the connection point to the high voltage grid). These cables were responsible for producing reactive power. Ellevio faced restrictions on how much reactive power they could send to the grid, leaving them with a need to offset the amount being produced.
Additionally, with such a heavy and dynamic load to compensate, Ellevio needed to implement a solution that would be able to measure and to be connected on 130kV.
Other issues included the fact that in this region of Sweden, the environment can become quite harsh, meaning Ellevio needed a solution that could be completely sealed off to protect the equipment and avoid issues like overheating. The wind farm is also far from any urban area, so having remote access and easy serviceability was important for Ellevio as part of their decision criteria.
*Capacitive cables occur in instances when conductors are close together, i.e. when the cables are put in the ground.
After an initial assessment, Comsys installed an ADF STATCOM that added inductive current to compensate the reactive power produced by the cables. Sized at 2.5 MVA, this is a high power, utility grade STATCOM ideal for heavy industrial loads.
ADF STATCOMs can be integrated into existing on-site infrastructure or they can be commissioned with their own housing. As Ellevio was already constructing on-site housing for switch gears, the ADF STATCOM solution was integrated into the switch gear housing thereby avoiding unnecessary cost and making installation that much simpler.
With the ADF STATCOM, all the compensation is done on 690 V. However, by using a step-up transformer placed in between the system and the grid, ADF technology can connect to any voltage level. With this approach we were able to connect to 130kV from the turbines.
In order to meet Ellevio’s request that the compensation solution be protected from the elements, the team went with an ADF P300 liquid cooled solution.
The last and smallest piece of the installation was a 3G modem installed in the building to enable wireless access to the ADF STATCOM, giving Comsys full access for remote monitoring and service.
Products used in this case:
ADF P300, liquid cooled
Now compliant with the grid restrictions, the Ellevio wind farm has been operating smoothly since commissioning. In the years since the installation (2013), they have requested that Comsys check up on the system to make sure everything is running as well as it appears. From their location in Lund, Comsys uses their remote access to monitor the system and support as needed.
With this solution, the ADF STATCOM automatically compensates from zero to maximum without any differences; in other words, the ADF technology can completely follow the load of the wind farm, so no matter the conditions, the ADF STATCOM will truly compensate the load actively and dynamically.