A Differential Protection Method for Transmission Lines Based on Virtual Braking Current

A technology for differential protection and transmission lines, which is applied in the direction of automatic disconnection emergency protection devices, circuit devices, emergency protection circuit devices, etc., which can solve problems such as protection misoperation, refusal to operate, and reliability decline, and achieve transition resistance Strong resistance, good adaptability and excellent reliability

Active Publication Date: 2018-01-19
STATE GRID CORP OF CHINA +2
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AI Technical Summary

Problems solved by technology

The braking amount of the split-phase current differential protection of the transmission line is generally selected from the phasor difference of the current on both sides of the line, but it is greatly affected by the load current. When a high-impedance fault occurs in the area under heavy load, the sensitivity of the current differential protection Reduced, there is a risk of refusal to move
[0003] In the existing technology, the current differential protection adopts ratio braking. For the braking amount, when the braking coefficient is selected too small, it may cause malfunction of the protection when an out-of-area fault occurs, and the reliability decreases. When the braking coefficient is too large, the Affects the sensitivity of the differential protection to internal faults

Method used

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  • A Differential Protection Method for Transmission Lines Based on Virtual Braking Current
  • A Differential Protection Method for Transmission Lines Based on Virtual Braking Current
  • A Differential Protection Method for Transmission Lines Based on Virtual Braking Current

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Embodiment Construction

[0035] The specific embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0036] Such as figure 1 as shown, figure 1 It is the flow chart of transmission line differential protection based on virtual braking current of the present invention. The present invention provides a transmission line differential protection method. By comparing the currents on both sides of the line, a virtual current is constructed, and the current retains a larger current at the same time. The phase information of the side and the amplitude information of the smaller current side, use the virtual current and the smaller current to form the braking amount. The transmission line differential protection of the present invention can self-adaptively adjust the action performance of the protection, has good self-adaptability, and under the condition of the same fault reliability outside the zone, the sensitivity of the criterion and...

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Abstract

The invention provides a power line differential protection method based on virtual brake current. The method includes the steps of I, acquiring bilateral current values of a power line and subjecting the bilateral current values to low pass filtering; II, performing Fourier transform to obtain phasors m and n; III, subjecting the phasors m and n to capacitance-current compensation; and IV, constructing virtual current, determining a differential protection basis criterion according to the virtual current, and judging whether differential protection acts or not. The method has the advantages that the differential protection criterion is well adaptive, highly sensitive to internal faults, insusceptible to load current and high in transition resistance; in case of external faults, protection is reliable and idle.

Description

technical field [0001] The invention relates to a method in the field of electric power system relay protection, in particular to a method for differential protection of transmission lines based on virtual braking current. Background technique [0002] As the main protection of the line, the current differential protection is widely used in the 220kV and above voltage level lines. The braking amount of the split-phase current differential protection of the transmission line is generally selected from the phasor difference of the current on both sides of the line, but it is greatly affected by the load current. When a high-impedance fault occurs in the area under heavy load, the sensitivity of the current differential protection Reduced, there is a risk of refusal to move. [0003] In the existing technology, the current differential protection adopts ratio braking. For the braking amount, when the braking coefficient is selected too small, it may cause malfunction of the pr...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26H02H3/26
Inventor 柳焕章王兴国周泽昕姜宪国
Owner STATE GRID CORP OF CHINA
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