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Distributed low-current ground wire selection method and wire selection system thereof

A technology of small current grounding and line selection method, applied in the direction of measuring electricity, measuring electrical variables, measuring devices, etc., can solve the problem of no distributed small current grounding line selection method, inconvenient maintenance and management of grounding protection devices, and difficult arrangements, etc. To achieve the effect of convenient layout and space location arrangement, reliable judgment results, and convenient device maintenance and management

Active Publication Date: 2019-09-10
李晓明 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

According to the knowledge of the inventor, there is still no accurate and available distributed small current grounding line selection method for the relay protection of the power system at present. The existing small current grounding line selection method and its system are all centralized, and the centralized small current grounding The line selection system needs to connect the zero-mode current of all lines connected to the same bus section to the same grounding line selection device (grounding protection device). There may be more than 20 power supply lines in the same bus section. Therefore, The lead-in wires of the grounding protection devices need a lot, and it is not easy to arrange them in the space, and it is also very inconvenient for the maintenance and management of each grounding protection device

Method used

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  • Distributed low-current ground wire selection method and wire selection system thereof
  • Distributed low-current ground wire selection method and wire selection system thereof
  • Distributed low-current ground wire selection method and wire selection system thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0036] A typical implementation, such as figure 1 The distributed small current grounding line selection system shown. The power supply sends power to the transformer T, the transformer T sends power to the bus M, and the neutral point of the transformer T is grounded through the arc suppression coil L. Suppose the bus M is connected with N power supply lines, N=6. The six lines are L1, L2, L3, L4, L5, and L6. Each line has its own ground protection device BH1, BH2, BH3, BH4, BH5, BH6, for the convenience of drawing, figure 1 Only draw BH1. The zero-mode current i of the current transformers TA1, TA2, TA3, TA4, TA5, and TA6 of the 6 power supply lines 0,i (i=1, 2, 3, 4, 5, 6) respectively input the grounding protection devices BH1, BH2, BH3, BH4, BH5, BH6 of each line, zero-mode current i 0,i The reference direction is consistent with the convention that the busbar points to the line. i 0,i represents an instantaneous value, Represents a phasor. As we all know, the po...

Embodiment 2

[0056] Such as figure 1 In the distribution network shown, the A, B, and C phases of the transformer T have current transformers TAa, TAb, and TAc respectively. The current transformers TAa, TAb, and TAc respectively reflect the primary side current i a,T i b,T i c,T . However, the A and C phases of the transformer T in some distribution networks have current transformers respectively, and the B phase does not have a current transformer.

[0057] Field actual operation experience shows that when a ground fault occurs in a small current grounding system, the attenuated DC component of the neutral point arc suppression coil of the transformer is very small, and ignoring it has little effect on the line selection criterion for small current grounding. Therefore, when phase B is the faulty phase, let transformer T faulty phase remove power frequency and high frequency residual current i g,T,α =-(i a,T,α + i c,T,α ), still can use the disclosed method to select the fault lin...

Embodiment 3

[0059] Such as figure 1 In the distribution network shown, the A, B, and C phases of the transformer T have current transformers TAa, TAb, and TAc respectively. The current transformers TAa, TAb, and TAc respectively reflect the primary side current i a,T i b,T i c,T . In order to further reduce the lead-in wires of the ground protection device, the ground protection device can only take one-phase current, for example, take A-phase current.

[0060] It is not difficult to analyze, when phase B is the fault phase, the power frequency and high frequency residual current i of transformer T fault phase g,T,α =-2i a,T,α , to perform calculations, the fault line can still be selected with the disclosed method. When phase C is the fault phase, let transformer T fault phase remove power frequency and high frequency residual current i g,T,α =-2i a,T,α , to perform calculations, the fault line can still be selected with the disclosed method. However, the sensitivity and reliabi...

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Abstract

The invention provides a distributed low-current ground wire selection method and a wire selection system thereof. A ground protection device of each circuit is used for respectively obtaining voltageof each phase of a busbar, respectively obtaining three-phase phase or two-phase current of a power supply transformer connected with the busbar and obtaining zero-mode current of a protected circuit. The distributed low-current ground wire selection method is characterized by judging fault circuits by judging whether waveforms of power-frequency-free and high-frequency-free remaining current ofa fault phase of the transformer and zero-mode power-frequency-free and high-frequency-free remaining current of the circuit are in opposite directions. Through the distributed low-current ground wireselection method and the wire selection system thereof, the ground protection devices are few in leading-in wires and are convenient to maintain and manage.

Description

technical field [0001] The disclosure belongs to the field of relay protection of electric power systems, and in particular relates to a distributed small current grounding line selection method and a line selection system. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] The small current grounding system includes the neutral point ungrounded system and the neutral point grounded system through the arc suppression coil. According to the knowledge of the inventor, there is still no accurate and available distributed small current grounding line selection method for the relay protection of the power system at present. The existing small current grounding line selection method and its system are all centralized, and the centralized small current grounding The line selection system needs to connect the zero-mode current of all lines connecte...

Claims

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Application Information

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IPC IPC(8): G01R31/08
CPCG01R31/088
Inventor 李晓明
Owner 李晓明
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