Low-voltage direct current in power distribution of elevator car
Jalonen, Topi (2024)
2024
Sähkötekniikan DI-ohjelma - Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2024-12-02
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-2024112710584
https://urn.fi/URN:NBN:fi:tuni-2024112710584
Tiivistelmä
In the development of electricity distribution systems, low-voltage direct current (LVDC) systems are a significant factor. Challenges of traditional power distribution systems are complexity of their structures and thus reduced efficiency. Also, electricity is increasingly produced and consumed as direct current. As a result, more efficient and simpler LVDC systems have been researched to replace traditional power distribution systems. LVDC systems have proven to be more efficient and simpler in several applications compared with traditional alternating current (AC) systems. The benefits of LVDC systems are significant factors in mitigating climate change and promoting sustainable development.
The main objective of this thesis was to compare the differences between the conventional and LVDC power distribution systems of elevator car. The study compared differences between efficiency of the distribution systems and investigated whether the power distribution of elevator car is simplified when using LVDC system. During the thesis, it was also investigated what factors need to be considered when dimensioning the cable that is used to feed elevator car. In the theory of the research, a literature review was used, while in empirical research the measurements performed in the thesis were carried out.
Power distribution tests performed in the study showed that the efficiency of the system implemented with LVDC was about 50 %, which was slightly lower than the theoretically modelled efficiency, which was about 52 %. Based on the theoretical values, it was expected that efficiency of conventional power distribution system would be worse than efficiency of LVDC system, as theoretical efficiency of the conventional system was calculated to be about 38 %. Based on measurements the efficiency of conventional power distribution system was about 28 %, which was even worse than modelled. Hence, by utilizing LVDC system it was possible to increase efficiency of the power distribution of elevator car.
The measurements showed that the cable used in the power distribution system can withstand instantaneous high current peaks caused by the dynamic load in the test setup. The limiting factor was the high voltage drops in the cable during the current peaks. For this reason, the used cable cannot be dimensioned too small, but the size of the cable and the used voltage level have to be optimized.
During the research was found that the power distribution system of elevator car can be simplified by using LVDC system. It is possible to reduce the number of components needed for voltage conversions in the system. However, the system may become partially complicated, since the alternating voltage from the distribution network has to be rectified before it can be used in LVDC system. There may also be components in elevator car that require AC to operate, in which case separate inverters need to be added to them. Nevertheless, it can be concluded that LVDC system can be used to reduce the number of components and thus also to improve the efficiency of the system.
The main objective of this thesis was to compare the differences between the conventional and LVDC power distribution systems of elevator car. The study compared differences between efficiency of the distribution systems and investigated whether the power distribution of elevator car is simplified when using LVDC system. During the thesis, it was also investigated what factors need to be considered when dimensioning the cable that is used to feed elevator car. In the theory of the research, a literature review was used, while in empirical research the measurements performed in the thesis were carried out.
Power distribution tests performed in the study showed that the efficiency of the system implemented with LVDC was about 50 %, which was slightly lower than the theoretically modelled efficiency, which was about 52 %. Based on the theoretical values, it was expected that efficiency of conventional power distribution system would be worse than efficiency of LVDC system, as theoretical efficiency of the conventional system was calculated to be about 38 %. Based on measurements the efficiency of conventional power distribution system was about 28 %, which was even worse than modelled. Hence, by utilizing LVDC system it was possible to increase efficiency of the power distribution of elevator car.
The measurements showed that the cable used in the power distribution system can withstand instantaneous high current peaks caused by the dynamic load in the test setup. The limiting factor was the high voltage drops in the cable during the current peaks. For this reason, the used cable cannot be dimensioned too small, but the size of the cable and the used voltage level have to be optimized.
During the research was found that the power distribution system of elevator car can be simplified by using LVDC system. It is possible to reduce the number of components needed for voltage conversions in the system. However, the system may become partially complicated, since the alternating voltage from the distribution network has to be rectified before it can be used in LVDC system. There may also be components in elevator car that require AC to operate, in which case separate inverters need to be added to them. Nevertheless, it can be concluded that LVDC system can be used to reduce the number of components and thus also to improve the efficiency of the system.