Short-circuit faults and lightning protection for multi-circuit transmission lines with different voltage levels on a single tower

This article presents the design scheme of a wideband Wilkinson Power Divider (WPD) with two-stage architecture utilizing quarter-wave transmission lines and short-circuit stubs. The bandwidth of the proposed WPD is flexible and can be controlled using the design parameters. The proposed design achieves excellent isolation between output ports in addition good in-band performance. The analysis of the proposed circuit results in a simplified transfer function which is then equated with a standard band-pass transfer function to determine the parameters of transmission lines, stub’s impedances, and the value of the isolation resistors. Furthermore, it is also demonstrated that a simple alteration in the proposed circuit enables the design of a wideband DC isolated WPD that maintains a good in-band and isolation performance. A number of case studies have been included to highlight the flexibility of the proposed design. Two distinct prototypes are developed on different boards to demonstrate the wideband performance of the proposed design. An excellent agreement between the experimental and measured results for both the designs over a wide band including very good isolation between ports validate the proposed design.

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Development of the Method of Determining the Location of a Short Circuit in Transmission Lines

SSRN Electronic Journal ◽

10.2139/ssrn.3958875 ◽

2021 ◽

Author(s):

Konstantin Suslov ◽

Nafisa Solonina ◽

Zoya Solonina ◽

Azat Akhmetshin

Keyword(s):

Transmission Lines ◽

Short Circuit

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

Applied Sciences ◽

10.3390/app9091737 ◽

2019 ◽

Vol 9 (9) ◽

pp. 1737 ◽

Cited By ~ 1

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.

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Study on the Power-Frequency Waves Distribution Characteristics for Half-Wavelength Transmission Lines Based on the Frequency-Length Factor

Mathematical Problems in Engineering ◽

10.1155/2020/3497625 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14 ◽

Cited By ~ 1

Author(s):

Chang Chen ◽

Xiaoyang Ma ◽

Honggeng Yang ◽

Weikang Wang ◽

Yilu Liu

Keyword(s):

Transmission Lines ◽

Short Circuit ◽

Distribution Characteristics ◽

System Parameters ◽

Frequency Resonance ◽

Fault Resistance ◽

Maximum Value ◽

Half Wavelength ◽

Power Frequency ◽

Short Circuit Fault

To analyze the distribution characteristics of voltage and current along half-wavelength transmission lines (HWTLs) in the cases with or without short circuit in the steady state, the method based on the frequency-length factor (FLF) for lossy lines is proposed. Firstly, according to the pole condition of the FLF, the distribution characteristics of power-frequency waves along HWTLs are analyzed. Then, the comprehensive effects of the system parameters and fault resistance are explored, revealing the mechanism of the power-frequency resonance caused by nonmetallic short circuit. Meanwhile, unbalanced short-circuit fault is studied by exploiting additional impedance. The results show that the distribution of the maximum value of power-frequency resonance voltage is related to the system parameters but not to the fault impedance. When a HWTL is short circuited at 2640 km∼2930 km, the resonance voltage can reach to 21 p.u. In relation to symmetrical short circuit, the resonance voltage appears at 1469 km from the short-circuit point, while the position moves towards the short-circuit point with the increase of additional impedance in asymmetrical short-circuit conditions. Additionally, the model theoretically proves that the power-frequency overvoltage induced by short circuit does not appear on a line whose length is less than 1469 km. Finally, cases are studied on PSCAD to verify the accuracy of the model.

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An Optimized Coordination Strategy between Line Main Protection and Hybrid DC Breakers for VSC-Based DC Grids Using Overhead Transmission Lines

Energies ◽

10.3390/en12081462 ◽

2019 ◽

Vol 12 (8) ◽

pp. 1462 ◽

Cited By ~ 1

Author(s):

Zheng ◽

Jia ◽

Gong ◽

Zhang ◽

Pei

Keyword(s):

Transmission Lines ◽

Power Transmission ◽

Short Circuit ◽

Power Grids ◽

Fault Line ◽

Long Distance ◽

Coordination Strategy ◽

Overhead Transmission Lines ◽

Depth Analysis ◽

Dc Breaker

Compared with alternating current (AC) power grids, the voltage-sourced converter (VSC)-based direct current (DC) grid is a system characterized by “low damping”, as a result, once there is a short-circuit fault on the DC transmission line, the fault current will rise more sharply and the influence range will be much wider within the same time scale. Moreover the phenomenon that a local fault causes a whole power grid outage is more likely to occur. Overhead transmission lines (OHLs) have been regarded as the mainstream form of power transmission in future high-voltage, large-capacity and long-distance VSC-based DC grids. However, the application of overhead transmission lines will inevitably lead to a great increase in the probability of DC line failure. Therefore, research on how to isolate the DC fault line quickly is of great significance. Based on the technology route for fault line isolation using DC breakers, on the basis of in-depth analysis of traditional coordination strategy, an optimized coordination strategy between line main protection and a hybrid DC breaker for VSC-based DC grids using overhead transmission lines is proposed in this paper, which takes the start-up output signal of line main protection as the pre-operation instruction of the corresponding hybrid DC breaker. As a result, the risks of blockage of the modular multilevel converter (MMC) closer to the fault position and of damage to power electronic devices in main equipment can be reduced effectively. Finally, the proposed coordination strategy was verified and analyzed through simulation.

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