Device for compensation of ground faults in HV distribution networks
Ground faults are most often caused by vegetation or birds coming into contact with high-voltage power line conductors. It is a dangerous condition that can cause:
- dangerous contact and step voltages,
- the risk of fire,
- the risk of interruption of the electricity supply.
The ground connection is traditionally compensated by an extinguishing reactor. However, this leaves a residual current.
Fig. : Experimental verification of the proposed compensator at the Kralovice substation (2021)
Wireless power transmission
Our researchers have developed a prototype of the wireless charging station for electric vehicles with a power output of 65 kW at power transfer efficiencies of up to 97 % and overall efficiencies of 94 % to 96 %. The system is designed for transmission distances between 15 and 25 cm, which is sufficient for today's electric vehicles. Also, the tolerances of the coupling element alignment are adequate for normal parking.
Moreover, the system respects current standards for wireless charging of electric vehicles and the hygienic limits of the ambient electromagnetic field. The safety systems for detecting foreign living and non-living objects in the active transmission zone are also based on standardization.
Partial research and development tasks are currently being carried out on the system to continuously improve the system and raise the level of a possible implementation for the customer.
Fig.: Laboratory prototype of a wireless transmission device for more than 50 kW
Solar street lighting system
This is a proposal for a comprehensive solar public lighting solution with a biodynamic lighting function.
The developed public lighting concept allows a controlled transition between warm and cold light. The proposed lighting allows the suppression of the unwanted blue light component during the night. The blue component of light affects the production of the hormone melatonin in the body, which influences the circadian rhythm (the biorhythm of wakefulness and sleep).
In this project, we are developing specific MPPT units used to extract maximum power from a solar panel. The proposed unit also includes the development of LED drivers for the possibility of changing the color of the light. We are also working on a unit to ensure proper charging and protection of the batteries, called BMS (Battery Management System). The battery of the solar system uses modern LTO cells (Lithium Titanate Oxide).
The current state of the art is mainly used to collect long-term operational data and verify the topology, with the expectation that we will expand the system to include other renewable energy options in the future.
Fig.: Demonstration of the biodynamic lighting function on a prototype of the proposed solar street lighting system located on the FEL campus.
Electronic Energy storage system (EESS)
The electronic energy storage system (EESS) integrates energy storage consisting of 12 battery packs and a power section based on 3 SHRack power converters in a rack-mounted rack. The EESS is designed for direct connection to the power grid at a voltage level of 3 x 400 V and a rated current of 86 A. The functional sample is designed for a maximum continuous power of 60 kVA.
Power Grid Diagnostics - Injector
The current injection module is designed to identify high voltage distribution system parameters and tune suppression reactors. The module performs multi-tone (multi-frequency) current injection into the distribution network and, based on the frequency response, evaluates the optimal tuning point of the suppression inductor, which is crucial for maximum compensation efficiency during ground faults.
In cooperation with Eaton company we are working on the development of an electronic circuit breaker mainly for DC networks. In our laboratories we test the developed prototypes including automated lifetime tests of circuit breakers with pulse currents up to 1kA.
Fig.1: Laboratory Prototype of Electronic Breaker