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Abstract

The topology of low-voltage distribution systems changes with the load or the on/off position of the circuit switch. This will affect power flows, losses, and so on. This paper submits a new method to identify the topology of a low-voltage feeder using the injection high-frequency signal. An inductor can block the high-frequency signal. It can change the propagation direction of the injected high-frequency signal to make it propagate unidirectionally along the low-voltage feeder. By injecting a 5 MHz sinusoidal signal from the upstream direction of the low-voltage feeder, all the line segments and devices on the feeder can be identified. The wavelength of the high-frequency signal is short. The wavelength of the 5 MHz signal is 60 meters. Through the delay of different observation points on the feeder, the length of the line section can be roughly calculated. The highfrequency signal has an obvious reflection on the feeder. Using this feature, we can roughly calculate the length of the line segment. The correctness of the method is demonstrated by MATLAB simulation verification.
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Bibliography

[1] Thomas Allen Short, Electric Power Distribution Handbook, Second Edition, CRC Press (2014).
[2] Kersting W., Distribution System Modeling and Analysis, Fourth Edition, CRC Press (2017).
[3] Grotas S., Yakoby Y., Gera I. et al., Power Systems Topology and State Estimation by Graph Blind Source Separation, IEEE Transactions on Signal Processing, vol. 67, no. 8, pp. 2036–2051 (2019).
[4] Jun Jiang, Ling Liu, Resonance mechanisms of a single line-to-ground fault on ungrounded systems, Archives of Electrical Engineering, vol. 69, no. 2, pp. 455–466 (2020).
[5] Fan Kaijun, Xu Bingyin, Dong Jun et al., Identification method for feeder topology based on successive polling of smart terminal unit, Automation of Electric Power Systems, vol. 39, no. 11, pp. 180–186 (2015).
[6] Zhu Guofang, Shen Peifeng, Wang Yong et al., Dynamic identification method of feeder topology for distributed feeder automation based on topological slices, Power System Protection and Control, vol. 46, no. 14, pp. 152–157 (2018).
[7] Li X., Poor H.V., Scaglione A., Blind topology identification for power systems, 2013 IEEE International Conference on Smart Grid Communications (SmartGridComm), IEEE, pp. 91–96 (2013).
[8] Lazaropoulos A.G., Measurement Differences, Faults and Instabilities in Intelligent Energy Systems– Part 1: Identification of Overhead High-Voltage Broadband over Power Lines Network Topologies by Applying Topology Identification Methodology (TIM), Trends in Renewable Energy, vol. 2, no. 3, pp. 85–112 (2016). [9] Lazaropoulos A.G., Improvement of Power Systems Stability by Applying Topology Identification Methodology (TIM) and Fault and Instability Identification Methodology (FIIM) – Study of the Overhead Medium-Voltage Broadband over Power Lines (OVMVBPL) Networks Case, Trends inRenewable Energy, vol. 3, no. 2, pp. 102–128 (2017).
[10] Passerini F., Tonello A.M., Power line network topology identification using admittance measurements and total least squares estimation, 2017 IEEE International Conference on Communications (ICC), pp. 1–6 (2017).
[11] Soumalas K., Messinis G., Hatziargyriou N., A data driven approach to distribution network topology identification, 2017 IEEE Manchester PowerTech, pp. 1–6 (2017).
[12] Ge Haotian, Xu Binyin, Topology Identification of Low Voltage Distribution Network Based on Current Injection Method, Archives of Electrical Engineering, vol. 70, no. 2, pp. 297–306 (2021).
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Authors and Affiliations

Haotian Ge
1
Bingyin Xu
1
Xinhui Zhang
1
Yongjian Bi
1

  1. Shandong University of Technology, China
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Abstract

Short-term contact losses between a pantograph and a contact wire are not included in the standards nor are they taken into account in evaluating pantograph-contact wire interaction. These contact losses, however, accelerate wear and tear as well as disturb operation of vehicles’ drive systems. The article presents the effects of short-term contact breaks as well as an analysis of impact of contact breakages on a vehicle’s current at 3 kV DC power supply. Results of voltage and current oscillations measured in real conditions when pantograph of a DC driven chopper vehicle was running under isolators were presented. Then a simulation model of a vehicles with ac motors and voltage inverters was derived to undertake simulation experiments verifying operation of such a vehicle in condition similar to those measured in real condition.

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Authors and Affiliations

T. Maciołek
M. Lewandowski
A. Szeląg
M. Steczek
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Abstract

A probable risk for different diseases has been reported due to exposure of peoples living in the vicinity of electrical substations and electrical workers. The aim of this paper is to examine and reduce the induced current density due to the power system field acting on human beings in the working environment, by using the spheroidal calculation model. The results obtained by means of computer programs developed by the author in the MATLAB environment are compared with the limit values given by the International Committee on Non-Ionizing Radiation Protection (ICNIRP) for demonstrating the degree of danger due to the induced current and have a certain guidance function for worker’s health to ensure their safety.

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Authors and Affiliations

Manel Bidi
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Abstract

Currently, overhead lines dominate in the Polish medium and low voltage distribution networks. Maintaining their high reliability constitutes a very important challenge, especially under the severely changing climate conditions. An overhead power line exposed to high ice and rime loads has been considered. Using the finite element method (FEM), mechanical reliability of the distribution infrastructure was examined under various atmospheric conditions. Loads under the stressful conditions of rime, ice and wind were determined for the weakest section of the 30 kV overhead line, which consisted of concrete poles and ACSR conductors. SAIDI and SAIFI reliability indices and costs were determined for several variants of object reconstruction. The results allowed for determination of a solution relying on relocating the cables of all lateral branches and main line ice protection, through a system based on a weather-coordinated increase of the electrical load. To verify the solution proposed, a field experiment was conducted. The experiment confirmed the effectiveness of the solution proposed that appears to be universal. The paper is a result of synergic cooperation of two academic teams, i.e. a mechanical and electrical power engineering one, and the distribution system operator (DSO).

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Authors and Affiliations

W. Ciesielka
A. Gołaś
K. Szopa
W. Bąchorek
M. Benesz
A. Kot
S. Moskwa
P. Zydroń

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