Study on Constant in Short Circuit Current Calculation Formula of Induction Motor

Current limiting reactor can increase systems short circuit impedance so as to limit short circuit current. Current limiting reactor is directly involved in whole short circuit process when a short circuit fault occurs in a power system, which makes short-circuit current change more complex. Short circuit current level is affected by current limiting reactors parameters; a current limiting reactor with proper impedance value can maintain short-circuit current at an acceptable range. A short circuit transient process of a distributing network with current limiting reactor was analyzed, and the formula of current changing in short circuit transient process was deduced; according to the current changing formula, an engineering calculation formula of current limiting reactors impedance was derived. The case calculation shows that current limiting reactor meeting the need of the engineering calculation formula can reach the system current limiting requirement.

Download Full-text

Inductive influence of 25 kV, 50 Hz electrified single rail traction system

MATEC Web of Conferences ◽

10.1051/matecconf/201818006004 ◽

2018 ◽

Vol 180 ◽

pp. 06004

Author(s):

Bosko Milesevic ◽

Ivo Uglesic

Keyword(s):

Short Circuit ◽

Short Circuit Current ◽

Induced Voltage ◽

Metallic Structures ◽

Railway System ◽

Supply Current ◽

Traction System ◽

Current Calculation ◽

Inductive Interference

The paper presents the methodology for calculation and measurement of induced voltage caused by railway system operation on the sensitive metallic structures. The arrangement and characteristics of railway system 25 kV, 50 Hz are provided. The procedures of short-circuit current calculation and supply current measurement in the railway system are described. The basic theoretic background of inductive interference is explained. The reduction factors of the communication cable, railway system and environment are mentioned and clarified. On a case study, the results of the induced voltage calculation and measurement is compared. It is proved that induced voltage directly depends of supply current or shortcircuit value.

Download Full-text

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.

Download Full-text