Single-pole earth fault protection method for four-rail traction power supply system
A technology for traction power supply systems and ground faults, applied in fault locations, emergency protection circuit devices, fault detection according to conductor types, etc., can solve problems such as tripping of substations, expanding the scope of power outages, and difficulty in distinguishing current sizes, so as to avoid The effect of protecting against malfunction and avoiding malfunction
Active Publication Date: 2020-07-31
SOUTHWEST JIAOTONG UNIV
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Problems solved by technology
However, there are two problems in the existing technology: (1) it can only detect positive pole-to-ground faults; (2) when the four-rail traction power supply system includes three or more substations, the magnitude of the current flowing through the unidirectional conduction devices of each substation The proximity is indistinguishable, causing multiple substations to trip, the protection method is not selective, and the scope of the blackout is expanded
Method used
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[0107] Specific embodiments: Taking the DC1500V subway four-rail traction power supply system as an example, four cases of positive pole-to-ground fault, negative pole-to-ground fault, current sensor disconnection, and voltage sensor disconnection are respectively described in combination with schematic diagrams.
[0108] 1. Positive pole to ground fault
[0109] Taking five substations as an example, substation A to substation E divide the power supply section from left to right into section one to section four. At a certain moment, a positive pole-to-ground fault occurs at a certain point in Section 2. According to the fault pole judging method proposed in the present invention, the positive pole-to-ground fault criterion is |U + |set1 ,|U + -U - |>U set2 , to satisfy the delay T set1 Afterwards, the protection system determines that the fault type is a positive pole-to-ground fault, and each traction station controls the negative pole unidirectional conduction device t...
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A single-pole earth fault protection method for a four-rail traction power supply system comprises the steps: detecting positive pole earth voltage and negative pole earth voltage of each substation are detected, judging that a negative pole or positive pole earth fault happens to the system, and closing a positive pole or negative pole one-way conduction device; calculating the differential current of each section; and cutting off the section with the differential current greater than the current setting value. The method further comprises the steps of current sensor disconnection judgment and locking protection, and voltage sensor disconnection judgment and locking input of the one-way conduction device. According to the invention, the positive pole-to-ground fault and the negative pole-to-ground fault can be reliably judged, so that each substation is put into a non-fault pole one-way conduction device to form a fault loop; the circuit breakers on the two sides of the fault sectioncan reliably act to remove faults, and the non-fault section is reliable and does not act; the current sensor disconnection criterion can reliably avoid protection maloperation caused by current sensor disconnection; and the voltage sensor disconnection criterion can reliably avoid misoperation of the one-way conduction device caused by voltage sensor disconnection.
Description
technical field [0001] The invention relates to the technical field of subway traction power supply systems, in particular to a single-pole-to-ground fault protection method for a four-rail traction power supply system. Background technique [0002] The four-rail traction power supply system uses a special return rail to return the current to eliminate stray current from the source, and has broad development prospects in the subway field. The four-rail traction power supply system is a symmetrical suspension system, and its single-pole-to-ground fault (including positive pole-to-ground fault or negative pole-to-ground fault) and its relay protection method must be paid attention to. Otherwise, if the first pole-to-ground fault cannot be detected and removed as soon as possible, it may cause more serious pole-to-pole faults, which will be detrimental to the safe and reliable power supply of the subway. [0003] The existing relay protection technology of the four-rail tracti...
Claims
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Login to View More IPC IPC(8): H02H7/26G01R31/08
CPCG01R31/086H02H7/26
Inventor 韩正庆左光耀刘淑萍沈睿韦晓广
Owner SOUTHWEST JIAOTONG UNIV