scholarly journals Substation protection method for missing measurement information of transformer and bus connecting line

2021 ◽  
Vol 261 ◽  
pp. 01042
Author(s):  
Wei Liu ◽  
Yuxue Wang ◽  
Zengchao Wang ◽  
Zhile Xu ◽  
Yiquan Li ◽  
...  
Keyword(s):  
Synthesis Method ◽  
Simulation Software ◽  
Measurement Information ◽  
Inrush Current ◽  
Differential Protection ◽  
Protection Method ◽  
Electromagnetic Transient Simulation ◽  
The Stability ◽  
Types Of Faults ◽  
Smart Substation

In order to solve the problems of protection misoperation and refusing to operate caused by the lack of measurement information in smart substation, a substation protection method which can effectively eliminate the influence of transformer inrush current and bus CT saturation when the measurement information of substation and bus connecting line is missing is proposed. Through the theoretical analysis of current synthesis method based on Kirchhoff current law, it is proved that transformer inrush current and bus CT saturation will lead to the misjudgment of differential protection. Accordingly a new method of station protection is proposed to deal with the lack of measurement information. In order to verify the correctness of the method, taking a typical 220kV substation model as an example, PSCAD / EMTDC electromagnetic transient simulation software is used to simulate and verify different conditions and different types of faults. The results show that the proposed protection method can accurately eliminate the interference of transformer inrush current and bus CT saturation, ensure the correct action of differential protection, and improve the stability of substation when the measurement information is missing.

scholarly journals Study on instability failure mode and monitoring early warning standard of surrounding rock in fully weathered argillaceous sandstone section of large section tunnel

2019 ◽  
Vol 136 ◽  
pp. 04023
Author(s):  
Ming Zhao ◽  
Ke Li ◽  
Hong Yan Guo ◽  
KaiCheng Hua
Keyword(s):  
Limit State ◽  
Stable State ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Large Section ◽  
Rock Stability ◽  
Geological Conditions ◽  
Construction Step ◽  
The Face ◽  
The Stability

Based on the special geological conditions of a tunnel in Qingyuan section of Huizhou-Zhanzhou Expressway, FLAC3d numerical simulation software is used to simulate the rheological properties and instability of surrounding rock in large-section fully weathered sandstone section, and the stability and loss of surrounding rock are analyzed. The deformation of the dome and the face at steady state is analyzed. It is found that: 1) when the surrounding rock is in a stable state, the deformation curve of the dome is smooth. When the surrounding rock of the face is unstable, the front of the face appears ahead. Deformation should be first strengthened on the surrounding rock in front of the face. 2) The arched foot is an important part of the instability of the surrounding rock. In order to prevent the expansion of the collapsed part, the arched part should be reinforced. 3) In order to obtain the limit state of surrounding rock stability, the strength of surrounding rock is reduced, and the strength reduction coefficient corresponding to the displacement sudden point is taken as the safety factor of rock stability around the hole, and the stability safety coefficients of surrounding rock of each construction step are greater than 1.2. 4) The dynamic standard values of deformation control in the whole construction stage are obtained by analyzing the deformation curves of each data monitoring point with time in the corresponding time period of each construction step.

The Feasible Analysis of Transformer Fast Reenergizing with Neutral Point Ungrounded

2013 ◽  
Vol 732-733 ◽  
pp. 958-964
Author(s):  
Yao Zhao ◽  
Yu De Yang ◽  
Yan Hong Pan ◽  
Le Qi
Keyword(s):  
High Voltage ◽  
Power Supply ◽  
Low Voltage ◽  
Second Harmonic ◽  
Neutral Point ◽  
Inrush Current ◽  
Differential Protection ◽  
Time Saving ◽  
Magnetizing Inrush Current ◽  
Transformer Differential Protection

The feasibility of transformer fast reenergizing with neutral point ungrounded after the external fault being removed is analyzed in this paper. By calculating overvoltage and discriminating magnetizing inrush current, it analyzes four ways to restore power of transformer and chooses the optimal strategy which is safe and time-saving. The result shows that in the case of transformer neutral point ungrounded, closing the low-voltage circuit side breaker before the high-voltage, which can effectively limit over-voltage in a safe range. The second harmonic characteristic of magnetizing waveform may disappear, while the intermittent angle characteristics are still significant. With the help of the intermittent angle principle, transformer differential protection may not misuse. The average time for each customer interruption is reduced from 40 minutes to 10 minutes and saves an hour for engineer on the way back and forth. It will greatly improve power supply reliability.

scholarly journals New Differential Protection Method for Multiterminal HVDC Cable Networks

2021 ◽  
Author(s):  
Ricardo Granizo Arrabé ◽  
Carlos A. Platero ◽  
Fernando Álvarez Gómez ◽  
Emilio Rebollo López
Keyword(s):  
Differential Protection ◽  
Cable Networks ◽  
Protection Method

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.

Fire Protection Studies on Steel Staggered-Truss Structure Based on Analytic Hierarchy Process

2010 ◽  
Vol 26-28 ◽  
pp. 608-611 ◽  
Author(s):  
Chang Kun Chen ◽  
Dong Zhang
Keyword(s):  
Analytic Hierarchy Process ◽  
Fire Protection ◽  
Design Method ◽  
Fire Retardant ◽  
Comparative Investigation ◽  
Truss Structure ◽  
Analytic Hierarchy ◽  
Protection Method ◽  
The Stability ◽  
Hierarchy Process

A new design method for fire protection, based on analytic hierarchy process (AHP), was put forward, to explore an economic and secure strategy for fire protection of steel staggered-truss structure (SSTS). The chords and web members of SSTS were classified into different important grades by AHP according to the influence which components make on the stability of structure at elevated temperature. And the components are protected by different levels based on the important grades. Furthermore, a comparative investigation was conducted in order to appraise the economic and practical performance of the provided new fire protection method with traditional fire protection. The results indicate that the proposed fire protection strategy for SSTS based on AHP could achieve higher security with the same volume of fire retardant coatings.

Current increment based DC differential protection method

2017 ◽  
Author(s):  
Yinglin Liu ◽  
Guomin Luo ◽  
Lin Zhou ◽  
Jinghan He ◽  
Ming Dai ◽  
...  
Keyword(s):  
Differential Protection ◽  
Protection Method
Sign in / Sign up

Export Citation Format

Share Document