The Voltage and Current Asimmetry on the LV System Caused by Consumers

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Supervisor:
Dr. Kiss Péter
Department of Electric Power Engineering

This thesis reviews the current- and voltage asymmetry in the 0.4kV system, caused by the single phase consumers. The voltage asymmetry is also known as voltage unbalance or -imbalance.

In the 2nd chapter the basic definitions, measuring algorithms and limits are introduced according to the Hungarian and different international standards. I show the main reasons of the voltage-and current asymmetry and the effects too.

In the next part of my thesis the computer model is presented, the model is realized in Microsoft Excel. With this Excel sheet the low voltage system asymmetry can be calculated and illustrated by tables, diagrams and phasor diagrams. The user manual of this Excel sheet is attached to the appendix.

In the longest part of this study, in the 4th chapter a case study is introduced demonstrating how the asymmetry can be formed at a low voltage transformer area. A fictional system and a real transformer area with real street segments and consumers are modelled.

In the 5th chapter I focus on the asymmetry reducing possibilities by changing the connection phase of the consumers. In this chapter the real transformer area is used. Different ways of phase change are presented, and their efficiency are compared.

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