**Acknowledgements**

This research was supported by project funding APVV – 17 – 0345 - Research of the optimization procedures for improvement of transfer, safety and reliability characteristics of WET systems. This research was also funded by the Ministry of Education, Youth and Sports of the Czech Republic under the project OP VVV Electrical Engineering Technologies with High-Level of Embedded Intelligence CZ.02.1.01/0.0/0.0/18\_069/0009855 and by funding program of the University of West Bohemia number SGS-2018-009.
