Method for achieving single-phase earth fault line selection of small current grounding system

A single-phase ground fault, small current grounding technology, applied in the direction of fault location, measuring electricity, measuring electrical variables, etc., can solve problems that have not been solved well, and achieve reliability assurance, high sensitivity, and improved adaptability Effect

Inactive Publication Date: 2014-02-19
珠海威瀚科技发展有限公司
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Problems solved by technology

[0006] It is an indisputable fact that the grounding line selection of the small current grounding system

Method used

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  • Method for achieving single-phase earth fault line selection of small current grounding system
  • Method for achieving single-phase earth fault line selection of small current grounding system
  • Method for achieving single-phase earth fault line selection of small current grounding system

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Embodiment Construction

[0029] figure 1 It is the line selection flow chart. figure 2 is the equivalent circuit when the line is single-phase grounded, image 3 It is the equivalent circuit when the bus is single-phase grounded. When the neutral point is grounded through the arc suppression coil, L is connected; when the neutral point is grounded through high resistance, R is connected; when neither L nor R is connected, it is a neutral point ungrounded system. C 1 ~C n is the equivalent capacitance of line 1~n; i 1 ~i n is the capacitive current of line 1~n, r g is the transition resistance of the grounding point.

[0030] Such as figure 2 As shown, the neutral point is assumed to be a single-phase grounding of line 1 of the ungrounded system. at i 0.1 >|I 0 | Moment, i 0.1 The direction of the line points to the bus M, and the non-faulty line i 0.2 ~i 0.n The direction of all points from M to the line, i 0.1 The sign of is unique, and i 0.2 ~i 0.n The sign of the non-faulty line ...

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Abstract

A method for achieving single-phase earth fault line selection of a small current grounding system is characterized in that a high-precision zero-sequence current transformer is adopted by each feeder line; a single-phase earth fault of the system is confirmed when the instantaneous value of the zero-sequence current i0 of any one feeder line exceeds a set threshold /I0 /; comparison is conducted on symbols of all loop circuits at the moment of threshold triggering, and data after the triggering do not participate in judgment; the symbol of a faulty line current is unique and opposite to the symbols of non-faulty line currents, and the number of non-faulty lines is larger than or equal to 2; when the symbols of all the currents are identical, a bus earth fault is confirmed. The method for achieving single-phase earth fault line selection of the small current grounding system is adaptable to three grounding modes, namely neutral non-grounding, arc suppression coil grounding and neutral point high resistance grounding, of the small current grounding system and is not affected by a grounding moment phase angle, system unreal grounding and TV disconnection, and correction operation can still be achieved when the zero-sequence voltage of a bus is reduced to be 10% of a phase voltage by a transition resistor.

Description

technical field [0001] The invention relates to a single-phase grounding fault line selection method for a small current grounding system, which is used for grounding line selection and fault location of a medium-voltage power grid system of 66kV or below. Background technique [0002] The neutral point of the 66kV and below medium-voltage power grid system in my country adopts a small current grounding system, including three grounding methods: ungrounded neutral point, high-impedance grounding and arc-suppression coil connection. leading position. With the advancement of automatic tracking and compensation technology, the characteristics of single-phase ground faults are becoming less and less obvious, and the correct action rate of the matching grounding line selection device is getting lower and lower, and at the same time, it has caused great difficulties for fault location in distribution network automation. . At the beginning of the century, it was estimated that 80-...

Claims

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Application Information

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IPC IPC(8): G01R31/08G01R31/02
Inventor 张振旗刘长利杨蒙
Owner 珠海威瀚科技发展有限公司
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