Protection method for heterophase short-circuit of tractive power supply system
A traction power supply system, out-of-phase technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve problems such as inability to operate, and achieve the effect of easy implementation and perfect performance
Inactive Publication Date: 2008-10-08
TIANJIN UNIV
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[0008] The invention proposes a different-phase short-circuit protection method for the situation that the conventional protection cannot operate when a different-phase short-circuit fault occurs in the traction power supply system
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[0023] The present invention will be further described in detail below in conjunction with the implementation principles and embodiments of the present invention.
[0024] Electrified railways use single-phase power supply. In order to make the electrified railway take current from the three-phase grid of the power system symmetrically, the electrified railway adopts the method of taking current by phase separation and segmentation, that is, a phase separation section is set every 20~25km, and adjacent phase separation sections are composed of two different phases. phase power supply, there is a power supply dead zone of about 30m adjacent to the phase-splitting area, and the dead zone is mainly composed of phase-splitting insulators. The function of the phase-splitting insulator is to isolate the electric energy of different phases on the traction network, so as to avoid short circuit between phases, and to play the role of mechanical connection, so that the traction network ...
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The invention relates to relaying protection technical field, especially to a protection method of traction power supply system heterophase short circuit, including following steps: calculating voltage among phases between two power supply arms real time collected by the relaying protection device, finding out fundamental wave effective value of the voltage; comparing the fundamental wave effective value of the voltage among phases with the setting voltage value, if less than or equal to the setting voltage value, calculating the third harmonic effective value of the voltage based on the sampling value of the voltage among phases between two power supply arms; calculating the ratio of the third harmonic effective value and the fundamental wave effective value, and comparing the ratio with the setting coefficient, if more than or equal to the setting coefficient, checking whether the protection device has PT break line sign or not, if not, the traction power supply system generates heterophase short circuit, the protection device sends out tripping signal. The invention can correctly recognise differences between the normal operation or general ground short circuit fault and the heterophase short circuit fault, having advantages of perfect performance and easy implement.
Description
technical field [0001] The invention relates to the field of relay protection of a traction power supply system, in particular to a method for out-of-phase short-circuit protection by detecting the voltage magnitude and third harmonic content between fault phases. Background technique [0002] Distance protection distinguishes internal and external faults by measuring the distance from the short-circuit point to the protection installation. It is the most widely used protection principle in the power system transmission network. The electrified railway traction power supply system is a special user of the power system, and conventional protection principles such as distance protection and current protection are still the main forms of feeder protection for traction power supply systems. In general, these protections can effectively act on conventional short-circuit faults, thus playing the role of feeder protection. However, when the system has out-of-phase short-circuit fa...
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Inventor 张艳霞周莹莹
Owner TIANJIN UNIV