Abstract
Owing to the installation of autotransformers at regular intervals along the line, distance protection relays cannot be used with the aim of locating ground faults in 2 × 25 kV railway power supply systems. The reason is that the ratio between impedance and distance to the fault point is not linear in these electrification systems, unlike in 1 × 25 kV power systems. Therefore, the location of ground faults represents a complicated task in 2 × 25 kV railway power supply systems. Various methods have been used to localize the ground fault position in 2 × 25 kV systems. The method described here allows the location of a ground fault to be economically found in an accurate way in real time, using the modules of the circulating currents in different autotransformers when the ground fault occurs. This method first needs to know the subsection and the conductor (catenary or feeder) with the defect, then localizes the ground fault’s position.
Highlights
The most widely used electrical configuration to feed high-speed trains is the 2 × 25 kV railway power system
The use of this system, compared to the traditional 1 × 25 kV railway power system, allows the required number of traction substations erected along the line to be reduced, because it has lower losses and lower voltage drops along the line [1]
The location method using travelling waves, in addition to transmission and distribution lines, has been applied to the lines of railway traction power systems, aided by advances in the theory of wave propagation, microelectronics and data processing [4]. In this method, when a ground fault occurs, there are various types of technologies to locate ground faults according to the detection of the generated travelling wave at one end [12] or at both ends [13], and if it is performed by the wave itself or by a pulse injected into one end when such a fault occurs [14]
Summary
The most widely used electrical configuration to feed high-speed trains is the 2 × 25 kV railway power system. A ground fault can be located by measuring the impedance in each conductor and return cable circuits This method is used in some 2 × 25 kV traction power systems, but it is very slow, requiring several operations of connection and disconnection of switches with waiting times between each maneuver [8,9]. The location method using travelling waves, in addition to transmission and distribution lines, has been applied to the lines of railway traction power systems, aided by advances in the theory of wave propagation, microelectronics and data processing [4] In this method, when a ground fault occurs, there are various types of technologies to locate ground faults according to the detection of the generated travelling wave at one end [12] or at both ends [13], and if it is performed by the wave itself or by a pulse injected into one end when such a fault occurs [14].
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