scholarly journals Construction and Modeling of Multi-Circuit Multi-Voltage HVAC Transmission Lines

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 421
Author(s):  
Agnieszka Dziendziel ◽  
Henryk Kocot ◽  
Paweł Kubek
Keyword(s):  
Transmission Lines ◽  
Short Circuit ◽  
Electrical Energy ◽  
Network Capacity ◽  
Mechanical Analysis ◽  
Symmetric Model ◽  
Correct Operation ◽  
Overhead Lines ◽  
Zero Sequence ◽  
The Impact

A transmission network’s main objective is to continuously supply electrical energy to consumers. This article presents an analysis of the use of multi-circuit, multi-voltage overhead lines as a compromise between ensuring the system’s safe operation by increasing the transmission network capacity and managing the constraints related to its expansion. The considerations presented in this work include the construction of such lines, their operation, and modeling aspects. As part of the study, the potential for improving the environmental conditions around the lines is discussed in terms of the necessary area for their construction and the peak electromagnetic field strength in their vicinity. We also present a mechanical analysis of stress and sag coordination in the individual circuits of these lines. Then, we detail the method for determining the electrical parameters of multi-voltage lines’ series impedances and capacitance. Specific attention is given to the possibility of zero-sequence voltage that occurs in the systems despite the symmetric supply and load of circuits—especially in the circuits with the lowest voltages—that result from the line’s geometric asymmetry. We evaluate the impact of the line’s geometric asymmetry on the power system’s correct operation by determining the asymmetry factors. Finally, the accuracy of using a simplified symmetric model for lines with various geometric asymmetries is analyzed by studying the error of the short-circuit currents.

scholarly journals A Novel Overcurrent Suppression Strategy during Reclosing Process of MMC-HVDC

2019 ◽  
Vol 9 (9) ◽  
pp. 1737 ◽  
Author(s):  
Bin Jiang ◽  
Yanfeng Gong
Keyword(s):  
Transmission Lines ◽  
Short Circuit ◽  
Current Method ◽  
Short Circuit Current ◽  
Simulation Software ◽  
Fault Current ◽  
Overhead Lines ◽  
Hvdc System ◽  
Electromagnetic Transient Simulation ◽  
Current Calculation

A modular multilevel converter based high-voltage DC (MMC-HVDC) system has been the most promising topology for HVDC. A reclosing scheme is usually configured because temporary faults often occur on transmission lines especially when overhead lines are used, which often brings about an overcurrent problem. In this paper, a new fault current limiter (FCL) based on reclosing current limiting resistance (RCLR) is proposed to solve the overcurrent problem during the reclosing process. Firstly, a mesh current method (MCM) based short-circuit current calculation method is newly proposed to solve the fault current calculation of a loop MMC-HVDC grid. Then the method to calculate the RCLR is proposed based on the arm current to limit the arm currents to a specified value during the reclosing process. Finally, a three-terminal loop MMC-HVDC test grid is constructed in the widely used electromagnetic transient simulation software PSCAD/EMTDC and the simulations prove the effectiveness of the proposed strategy.

scholarly journals Protection Method Based on Wavelet Entropy for MMC-HVDC Overhead Transmission Lines

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 678
Author(s):  
Weibo Huang ◽  
Guomin Luo ◽  
Mengxiao Cheng ◽  
Jinghan He ◽  
Zhao Liu ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Transmission Systems ◽  
Wavelet Entropy ◽  
Overhead Lines ◽  
Time Frequency ◽  
Protection Method ◽  
Distribution Features ◽  
The Impact

Recent technological developments in modular multilevel converter-based high-voltage direct current (MMC-HVDC) transmission systems have shown significant advantages over the traditional HVDC and two-level voltage source converter (VSC) transmission systems. However, there are a lack of studies on the protection methods for MMC-HVDC overhead lines where the protection method should be able to provide a fast and accurate response and be able to identify lightning strikes. In this paper, a wavelet entropy-based protection method is proposed. Due to the capability of revealing time–frequency distribution features, the proposed protection method combines wavelet and entropy to identify the time–frequency characteristics of different faults. Simulation results show that the proposed method can accurately and quickly determine the types of faults or disturbances with appropriate noise tolerance. In addition, the impact of the ground resistor and fault distance on the performance of the proposed method is studied.

scholarly journals Allocation of 0.4 kV PTL Sectionalizing Units under Criteria of Sensitivity Limits and Power Supply Reliability

2021 ◽  
Vol 11 (24) ◽  
pp. 11608
Author(s):  
Alina Vinogradova ◽  
Alexander Vinogradov ◽  
Vadim Bolshev ◽  
Andrey Izmailov ◽  
Alexey Dorokhov ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Power Supply ◽  
Power Transmission ◽  
Short Circuit ◽  
Reducing Power ◽  
Power Transmission Lines ◽  
Electrical Networks ◽  
The Cost ◽  
The Impact ◽  
Supply Reliability

Sectionalizing 0.4 kV power transmission lines (PTL) improves power supply reliability and reduces electricity undersupply through the prevention of energy disconnection of consumers in the event of a short circuit in the power line behind the sectionalizing unit (SU). This research examines the impact of sectionalizing on power supply reliability and reviews the literature on sectionalizing unit allocation strategies in electrical networks. This paper describes the experience of the use of sectionalizing units with listing strengths and weaknesses of adopted technical solutions and describes the new structure of sectionalizing units. A new methodology is proposed, whereby there are two criteria for allocating SU in 0.4 kV power transmission lines. The first criterion is the sensitivity limits against single-phase short circuits used for calculating the maximum distance at which SU can be installed. The second criterion is power supply reliability improvement, evaluating the cost-effectiveness of installing sectionalizing equipment by reducing power supply outage time. The established methodology was put to the test on an actual electrical system (Mezenka village, Orel area, Russia), which demonstrated that the installation of a sectionalizing unit paid off.

scholarly journals Study on Fault Analysis and early warning system of wind-induced disasters on transmission lines

2020 ◽  
Vol 194 ◽  
pp. 03016
Author(s):  
LIN Fanqin ◽  
JIA Ran ◽  
Yang Jingjing ◽  
CAO Huaming ◽  
LIU Hui ◽  
...  
Keyword(s):  
Wind Speed ◽  
Real Time ◽  
Transmission Lines ◽  
Early Warning ◽  
Early Warning System ◽  
Short Circuit ◽  
Power Grid ◽  
Warning System ◽  
Strong Wind ◽  
The Impact

Wind-induced disaster has become one of the most important disasters affecting the safe operation of power grid. In order to improve the effect of prevention and treatment of wind-induced disasters, it is very important to give early warning and real-time warning. Therefore, based on the climate characteristics of Shandong power grid, this paper presents the wind speed statistical law and the distribution characteristics of the number of days with strong wind. By analysing the mechanism of wind-induced disasters and combining the fault data of five years, the characteristics and rules of wind deviation and foreign short-circuit fault are obtained. On this basis, an early warning model of wind deviation based on the calibration of minimum air gap and the determination of maximum wind speed is established. At the same time, there is a short circuit model based on visual image information. Based on GeoServer platform, we will develop an early warning system for wind-induced disasters of transmission lines, which can provide real-time warning and early warning for wind-induced disasters. The application of the system can reduce the impact of wind damage on the transmission line, and effectively improve the operation reliability of the line.

scholarly journals The Impact of PLL Dynamics on the Low Inertia Power Grid: A Case Study of Bonaire Island Power System

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1259 ◽  
Author(s):  
Yin Sun ◽  
E. de Jong ◽  
Xiongfei Wang ◽  
Dongsheng Yang ◽  
Frede Blaabjerg ◽  
...  
Keyword(s):  
Short Circuit ◽  
Renewable Energy Sources ◽  
Rate Of Change ◽  
Power Grids ◽  
Voltage Source ◽  
Rotational Inertia ◽  
Synchronous Generators ◽  
Correct Operation ◽  
The Impact

To prepare for the future high penetration level of renewable energy sources, the power grid’s technical boundaries/constraints for the correct operation of powerelectronics interfaced devices need to be further examined and defined. This paper investigates the challenge of integrating Voltage Source Converters (VSC) into low inertia power grids, where the system frequency can vary rapidly due to the low kinetic energy buffer available, which used to be provided by the rotational inertia of synchronous generators. The impact of rate of change of frequency (ROCOF) on the PLL dynamics and its subsequent influence on the VSC power stage output is explained. The Bonaire island network is presented as case study. The performance of the VSC is analyzed under a fast ROCOF event, which is triggered by a short circuit fault. A down-scaled experiment is used to validate the Bonaire island network simulation results. It shows that the phase angle error measured by the synchronous-reference frame phase-locked loop (SRF-PLL) is proportional to the slope of the ROCOF and inversely proportional to its controller integral gain constant.

scholarly journals Impact of the Ground on the Series Impedance of Overhead Power Lines

2020 ◽  
Vol 7 (3) ◽  
pp. 47-54
Author(s):  
Anastázia Margitová ◽  
Michal Kolcun ◽  
Martin Kanálik
Keyword(s):  
Electrical Energy ◽  
Electric Power System ◽  
Power Lines ◽  
Electrical Parameters ◽  
Overhead Lines ◽  
Return Path ◽  
Overhead Power Lines ◽  
The Impact ◽  
Overhead Power Line ◽  
Series Impedance

An overhead power line is a structure used in the electric power system to transmit electrical energy. The performance of overhead power lines depends on their parameters. There are four basic electrical parameters of power lines: resistance, inductance, capacitance, and shut conductance. The paper focuses on the calculation of the series impedance of overhead lines (resistance and inductance) by three different methods (Carsonʹs method, Rüdenbergʹs method and the theory of complex penetration depth) considering the impact of the ground return path. There is also the comparison of these methods and their application on models of real power lines of different voltage levels provided in this paper.

scholarly journals The determination of short circuits and grounding faults in electric power systems using time-frequency analysis

2017 ◽  
Vol 26 (2) ◽  
pp. 123
Author(s):  
Vedat Esen ◽  
Bulent Oral Oral ◽  
Tahir Cetin Akinci
Keyword(s):  
Mathematical Method ◽  
Power Systems ◽  
Fourier Analysis ◽  
Transmission Lines ◽  
Power Transmission ◽  
Short Circuit ◽  
Electrical Energy ◽  
Power Transmission Lines ◽  
Time Frequency ◽  
Time Band

In order to ensure that electrical energy reaches consumers uninterrupted, researchers constantly try to improve power transmission lines. To realize this improvement, probable faults should be analysed through every known method, and new methods should also be implemented. In this study, firstly, the Keban power transmission line located in the Eastern Anatolia region of Turkey was modelled. After that, probable short circuit scenarios were applied on the model, and the short circuit faults in the scenarios were analysed by using the Fourier analysis. The Fourier analysis is a mathematical method that is used as an effective way to determine the sudden changes in the frequency and time band. The study was successful in determining phase and grounding faults through the analyses of the scenarios using Fourier analysis. The fact that the mathematical method was applied on the probable scenarios on a physical model increases the importance of the study.

Backup Protection for Six-Phase Transformer Based on Six-Sequence Components

2013 ◽  
Vol 385-386 ◽  
pp. 1127-1130 ◽  
Author(s):  
Hai Jiang Wang ◽  
Yan Xia Zhang ◽  
Zhong Yuan Deng
Keyword(s):  
Theoretical Analysis ◽  
Transmission Lines ◽  
Power Transmission ◽  
Short Circuit ◽  
Simulation Experiments ◽  
Backup Protection ◽  
System A ◽  
Sequence Components ◽  
Zero Sequence ◽  
Phase Transmission

The six-phase transmission can improve the power transmission density of the transmission lines effectively, and save line corridor. To save the problem that the sensitivity of the traditional transformer backup protection is low in six-phase transmission system, a backup protection for six-phase transformer was proposed. An over-current protection criterion is proposed for interphase short circuit and opposite zero sequence over-current protection criterion is proposed for ground faults, based on the six-sequence components relationship, and the existence of six-sequence components in different fault types. Theoretical analysis and EMTDC simulation experiments prove that the scheme is feasible.

Research on fault clearing scheme for half-bridge modular multilevel converters high voltage DC based on overhead transmission lines

2020 ◽  
Vol 22 (1) ◽  
pp. 61-72
Author(s):  
Jingru Zhang ◽  
Baina He ◽  
Xingmin He ◽  
Yanchen Dong ◽  
Renzhuo Jiang
Keyword(s):  
High Voltage ◽  
Transmission Lines ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Circuit Breakers ◽  
Multilevel Converters ◽  
Modular Multilevel Converters ◽  
Clearing Time ◽  
The Impact ◽  
Short Circuit Fault

Abstract When a short-circuit fault occurs on the transmission lines of high voltage DC transmission system based on modular multilevel converters, the fault cannot be cleared by adjusting the converter control system, which results in longer recovery time. Aiming at the problem above, a fault self-clearing scheme based on the fault clearing module for the half-bridge converter station is proposed. Combined with the actual operating status of the flexible DC transmission project, centralized parameter models are utilized to analyze the fault self-clearing mechanism. Besides, the impact of the discharge branch on the fault clearing effect is studied in depth to provide a design consideration for the fault clearing module and improve the comprehensive benefits of the proposed scheme. PSCAD/EMTDC simulation results show that the introduction of the fault clearing module in the half-bridge converter station can effectively suppress the fault short-circuit current and shorten the fault clearing time. In addition, circuit breakers on both sides of the line do not need to be tripped, providing a reliable guarantee for the subsequent adaptive restart process.

scholarly journals Breakage Mechanism Study of Overhead Ground Wire Under Lighting Stroke Based On Finite Element Analysis

2021 ◽  
Vol 237 ◽  
pp. 02011
Author(s):  
Yunfeng Xia ◽  
Fan Kuang ◽  
Ting Yang ◽  
Guanhao Chen ◽  
Rui Yang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Resistance ◽  
Temperature Rise ◽  
Short Circuit ◽  
Mechanism Study ◽  
Element Analysis ◽  
Overhead Lines ◽  
Breakage Mechanism ◽  
The Impact

Breakage of overhead transmission lines and distribution lines will lead to severe power outage problems, and clarifying the breakage mechanism of the overhead lines is of great importance and value for the reliability and stability of the power system. Taking overhead ground wire for example, this paper presents its breakage mechanism study under lighting stoke based on finite element analysis. A multi-physics analysis model is built first, which includes the model of contact points. The current density distribution and the temperature rise under the impact of short circuit current are analysed, and contact resistance effect is proved the primary cause for the breakage. Then some major factors that influence the contact resistance which in turn influence the temperature rise are discussed. Based on the discussions, some valuable suggestions are given for the protection of overhead lines.

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