Investigation of asymmetry based on low-voltage measurements

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Dr. Divényi Dániel Péter
Department of Electric Power Engineering

The asymmetry is a serious issue from the perspective of electric power quality and power losses on low voltage distribution network. The existing voltage asymmetry reduces the useful work drawn by consumers, actually it can also shorten the lifetime of their electrical equipment or even damage them. The load asymmetry generates heat which represents economical loss for the distribution companies. These and other effects can travel through the transformators to the medium and high voltage networks. That is why it is so important to lay great emphasis on handling the asymmetry.

In my study I review the internationally known methods of measuring and compensating asymmetry, that were formed according to different local traditions and standards. In the course of my work I developed a model for measuring asymmetry, which helped me analysing the data provided by ELMŰ Hálózati Kft. (distribution company of Budapest). These data include the monthly and yearly measurements of a small Hungarian town provided by the smart meters installed during the Smart Metering Multi Utility Project. I established the model using the monthly data that was provided. I also examined the asymmetry diluting effect of the temporal averaging.

The main point of my study is to develop a method how to judge the true level of asymmetry in the network based on shorter measurements. For this I used the yearly data of the Hungarian town to analyse the seasonal differences of the asymmetry. I compared the distributions of the calculated asymmetry norm for short periods to solve the task. The results demonstrated the yearly variation of the asymmetry. In my thesis I concluded whether the weekly measurement method of voltage asymmetry prescribed by the standards are suitable for assessing also the load asymmetry on the network.


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