Investigation the transfer characteristic of electricity network in the frequency range of 2 kHz to 150 kHz

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Dr. Ladányi József
Department of Electric Power Engineering

Nowadays the 2 – 150 kHz frequency range represents a standardization gap from the electromagnetic compatibility point of view. In the above-mentioned range, the relevant standards lack the specification of emission or immunity limits, except for some product standards.

With the development of power electronics, more and more grid-connected equipment appeared that contain power electronics: inverters, switching mode power supplies, uninterruptable power supplies, variable speed drives. Usually they operate with pulse width modulation, thus they can emit unacceptable disturbances at their switching frequencies and their multiplies. Based on international experience, these devices can influence other electronic equipment, for example the accuracy of smart meters or cause the loss of power line communication.

This thesis investigates the occurring anomalies in the frequency range mentioned above. After the theoretical introduction, I present the most frequently occurring electromagnetic interferences based on international experience. I also investigated the emitters in the 2 to 150 kHz frequency range. After that, a short overview discusses the actual situation of the standardization.

However, it is not enough to investigate the disturbance of emitters and susceptors, the coupling between them must also be examined. These are the elements of the low voltage network (e.g. transformers, wires, etc.). The second part of my thesis deals with researches related to these elements. First I review an examination performed on a medium voltage/low voltage transformer by the University of Dresden. My last task was to make an arrangement to measure the surface impedance of low voltage wires. After finding the appropriate arrangement, three different wires with 25, 50, and 95 mm2 cross-section made of AASC were measured and evaluated.


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