A relay protection method of a DC traction power grid

A relay protection, DC traction technology, applied in emergency protection circuit devices, electrical components, etc., can solve problems such as system malfunction, and achieve the effect of facilitating tuning, improving sensitivity and reliability

Inactive Publication Date: 2014-04-23
BEIJING INSTITUTE OF PETROCHEMICAL TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] From the perspective of the operation of the urban rail transit traction power supply system, in the DC traction current, the oscillating current that changes slowly and varies in length from positive to negative half cycles is the main reason for the system malfunction of the above protection methods

Method used

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  • A relay protection method of a DC traction power grid
  • A relay protection method of a DC traction power grid
  • A relay protection method of a DC traction power grid

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Embodiment Construction

[0020] The present invention is characterized by the 80-100ms cycle current in the DC traction current, adopts the HHT method to decompose the mode, and extracts the characteristic component It of the traction current (It is the current component of the 80-100ms cycle contained in the DC traction current) , and E (E is the setting value of It, the size of E value needs to be determined by HHT decomposition according to the existing wave recording data) value, and then execute the corresponding protection program. The specific method is as follows:

[0021] A relay protection method for a DC traction network, including a di / dt-ΔI protection program, if di / dt is always greater than A ， Then take whether ΔI exceeds the fixed value C (the set value of ΔI) as the criterion for tripping. Once ΔI exceeds the fixed value C, it will trip immediately; Within a certain period of time, if ΔI exceeds C, the protection trips immediately; if ΔI does not exceed the fixed value C, and di / dt i...

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Abstract

Provided is a relay protection method of a DC traction power grid. In an urban rail transit traction power supply section, 80 to 100ms cyclic current in DC traction current is used as characteristics and modal decomposition is performed by using a HHT method. The characteristic component It of extracted traction current (It is the current component of 80 to 100ms cyclic waves contained in the DC traction current) is compared with the value of E (E is an setting value of the It and the value of the E is determined by HHT decomposition according to obtained recorded data) and then a corresponding protective program is executed in order to improve the reliability of a protection system. The relay protection method is easy in setting and easy to be implemented in a conventional protection device.

Description

technical field [0001] The invention relates to a relay protection system for a power supply line, and is particularly suitable for the relay protection problem of traction power supply systems in urban rail transit. Background technique [0002] At present, the transient protection method of urban rail transit traction networks in various countries in the world adopts the current rising rate + current increment (di / dt- ΔI) protection method. The di / dt- ΔI protection is mainly used to cut off short-circuit faults at the middle and remote ends with small fault currents. The di / dt- ΔI protection is composed of two elements of instantaneous tripping and delayed tripping. The instantaneous tripping element depends on whether the current continues to increase. to determine the existence of faults. Whether the rate of change di / dt of the current exceeds the fixed value A is used as the criterion for starting, and the instantaneous value of di / dt and ΔI at each sampling poin...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/28
Inventor 李夏青
Owner BEIJING INSTITUTE OF PETROCHEMICAL TECHNOLOGY
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