Minimising grid faults caused by domestic appliances
Germany has one of the world’s most advanced grids. In the future, this grid will have to integrate more decentralised electricity generation systems on its low voltage level. In addition, electronic devices are becoming more efficient.
In most cases, this is a result of power electronics switches that operate above 2 kHz. The increasing number of these devices leads to rising emissions in the frequency range between 2 and 150 kHz. The phenomena that can occur, among other things due to propagation in the grid and impact on other devices, remain largely unexplored in this frequency range.
In recent years, there has been an increase in impermissible interferences, such as malfunctions of touch dimmer lamps, disturbing noise coming from televisions or an impact on the accuracy of electronic meters near photovoltaic inverters. This is due to emissions in the frequency range mentioned. Furthermore, there is a great deal of uncertainty with regard to economically sound compatibility levels and interference susceptibility and emitted inference limits with regard to developing the corresponding standards system.
Saving costs and securing grid compatibility
The research project VeNiFre150 (Grid compatibility in public low-voltage networks in the frequency range of 2 to 150 kHz) aims to make a significant contribution to the better understanding of the mechanisms of action and influence options with important fundamental studies. Thus, an appropriate co-ordination of emitted interference and interference susceptibility can be achieved in this frequency range, optimised with respect to the overall costs. This has the advantage of avoiding unnecessary costs for manufacturers, for example, by over-dimensioning filters, and too extensive grid expansion measures by grid operators. On the other hand, this research will allow for suitable grid compatibility in low voltage networks in Germany and Europe.
The project is being carried out by a research alliance between thenstitut für Energiesysteme, Energieeffizienz und Energiewirtschaft (IE3) at the Technical University of Dortmund, and the Institut für elektrische Energieversorgung und Hochspannungstechnik (IEEH) at Dresden University of Technology.
Project schedule: From literature and laboratory to practice
At the beginning of the research project, a comprehensive reappraisal of literature and standards for project-related aspects will be carried out. In addition, the methods and procedures used for grid and laboratory measurements are defined to allow for standardised logging and evaluation, which in turns allows for comparisons of the measurement results.
On this basis, two measurement setups are being built for the laboratory measurements. The first measurement setup serves to investigate the interference emitted by current domestic appliances and applications. Thus, researchers can characterise their typical interference levels in the relevant frequency range. In addition, measurements at specifically selected points in the low-voltage network are planned. The measuring points can be located near potential sources of interference such as PV systems. In doing so, the scientists gain insight into current situation of the low voltage networks. IEEH is in charge of these tasks.
IEEH is also initiating the second measurement setup, which is used to examine interference susceptibility. Its purpose is to characterise the interference susceptibility of the considered domestic appliances in terms of higher-frequency interferences. Thermal stress will also be analysed, and the influence of the different additional stresses on service life will be examined and evaluated.
With the information obtained, IE3 will then implement various methods and procedures to reduce higher-frequency loads for the investigated devices and distribution networks. This device optimisation includes circuitry changes to increase robustness against higher-frequency interference levels and to reduce emitted interference. To evaluate the optimisation measures, a laboratory prototype will be built, tested and analysed in terms of filter characteristics, size and efficiency.
Finally, different scenarios and strategies will be created for compatibility co-ordination purposes, in which the costs arising from possible damages or malfunctions are assessed. The IE3 scientists will carry out cost-benefit assessments based on the result. Their goal is to minimise the costs associated with the additional circuitry within the limits of the technical implementation options and existing standards, and to minimise limit values of emitted interference and interference susceptibility. As provided by the developed co-ordination strategies and scenarios, the minimum total costs are to be split amongst the device manufacturers and grid operators to ensure overall economically optimised grid compatibility.
05/2015 – 04/2018
Technische Universität Dortmund - Fakultät für Elektrotechnik und Informationstechnik