CN-121978452-A - Phase asymmetry principle line selection method

Abstract

The invention discloses a phase asymmetry principle line selection method, which comprises the steps of utilizing phase asymmetry and symmetry difference characteristics of a fault line, a sound line and a fault line non-fault phase on three-phase current abrupt change values during single-phase earth faults to realize fault line identification, utilizing current abrupt change value characteristic differences during single-phase earth faults to realize fault line identification, enabling the fault line fault phase current abrupt change values to be the sum of full-network capacitance currents, enabling the three-phase current abrupt change values to represent significant phase asymmetry, enabling the three-phase current abrupt change values of the sound line, the fault line non-fault phase and a fault point post-line to be all-phase capacitance current abrupt change values, enabling amplitude values to be basically consistent with waveforms, enabling phase symmetry to be represented, and adopting a temporary steady state data window combined sampling value redundancy selection design.

Inventors

• HAO LIPING
• DU JUAN
• LI ZHIYU
• LAN HAI
• LIU YUANMIN
• Mou nan
• KOU JIN
• ZHANG LIBO
• GAO DAN
• WANG CHAO
• YUAN JINMING
• ZHOU ZHONGQIANG
• YANG QIANG
• YAN HONGJUN
• ZHANG XIANGXIONG
• TAN YANYI
• TAO YONGWEI
• Pi Dinggui
• TIAN YU
• WANG LEI
• ZHOU BING
• FU TONGFU

Assignees

• 贵州电网有限责任公司

Dates

Publication Date

20260505

Application Date

20251219

Claims (10)

1. 1. A phase asymmetry principle line selection method is characterized by comprising the step of utilizing phase asymmetry and symmetry difference characteristics of a fault line, a sound line and a fault line non-fault phase on a three-phase current abrupt change quantity during single-phase earth fault to realize fault line identification.
2. 2. The phase asymmetry principle line selection method according to claim 1 is characterized by comprising the steps of collecting three-phase current sampling values of all lines of a power distribution network, calculating three-phase current abrupt change values of all lines, and determining maximum values, intermediate values and minimum values in three-phase abrupt change values of all sampling points according to the three-phase current abrupt change values.
3. 3. The method for selecting a line according to the phase asymmetry principle of claim 2, wherein if the three-phase current abrupt change of a certain line shows a phase asymmetry characteristic and satisfies a preset criterion condition, the line is determined to be a single-phase ground fault line, and if the three-phase current abrupt change of the certain line shows a relative characteristic, the line is determined to be a sound line.
4. 4. The phase asymmetry principle line selection method according to claim 3, wherein the criterion condition comprises an instantaneous asymmetry criterion for a single sampling point, and the instantaneous asymmetry criterion formula comprises maxΔi p (k)≥Δi set ;maxΔi p (k)≥k1×minΔi p (k);maxΔi p (k)-midΔi p (k)≥k2×(midΔi p (k)-minΔi p (k)）;midΔi p (k)≤k3×minΔi p (k）; Wherein, the 、 、 Respectively are sampling points Three-phase current abrupt change maximum, intermediate and minimum values; The phase current abrupt change is the minimum value; 、 、 is an asymmetry coefficient.
5. 5. The method for selecting a line according to the phase asymmetry principle of claim 4, wherein the calculating of the three-phase current abrupt change of each line is performed by using a periodic abrupt change calculation formula of Δip (k) = |ip (k) -ip (k-N) | -ip (k-N) -ip (k-2N) |; Wherein, the Is that Phase at The amount of periodic abrupt change of the dot, Taking any one of A, B, C phases; Is that Phase at Sampling a point current; The sampling point number is one power frequency cycle.
6. 6. The phase asymmetry principle line selection method according to claim 5, wherein the criterion condition further comprises an overall asymmetry criterion for the data window, the overall asymmetry criterion being required to satisfy: maxΔi p ≥k1×minΔi p; Wherein max delta i p is the maximum value of the periodic mutation amount screened by the phase with the largest mutation amount in the data window, and min delta i p is the maximum value of the periodic mutation amount screened by the phase with the smallest mutation amount in the data window.
7. 7. The phase asymmetry principle line selection method according to claim 6 is characterized in that after the starting element captures the moment of the ground fault, a transient data window or a steady-state data window is intercepted, the number of sampling points meeting an instantaneous asymmetry criterion is counted in the data window, and when the number of sampling points meeting the instantaneous asymmetry criterion exceeds a set threshold value and simultaneously meets an overall asymmetry criterion, the single-phase ground fault is identified.
8. 8. The method for selecting a line according to the phase asymmetry principle of claim 7, wherein the phase current is a minimum value The range of the value of (2) is 0.002 ~1.000 Wherein The secondary rated current of the current transformer is obtained.
9. 9. The method for selecting a line according to the phase asymmetry principle of claim 8, wherein the asymmetry coefficient is For describing the asymmetry of the maximum and minimum values, typically 3.00, the asymmetry coefficient For describing the asymmetry of the maximum value from the intermediate value, typically 4.00, the asymmetry coefficient For describing the asymmetry of the intermediate value from the minimum value, a typical value is 1.50.
10. 10. The method for selecting a line according to the phase asymmetry principle of claim 9, wherein the number of sampling points of the data window is Satisfy the following requirements Wherein The method is used for counting the sampling points of a power frequency cycle, and can finish the identification of single-phase grounding faults within 35 ms.

Description

Phase asymmetry principle line selection method Technical Field The invention relates to the technical field of single-phase grounding fault detection, in particular to a phase asymmetry principle line selection method. Background The delta I_PAM (delta I_ PhaseAsymmetryMethod) three-phase current abrupt change phase asymmetry principle is different from any other principle scheme, and the phase asymmetry among the three-phase current abrupt change caused by single-phase grounding faults is used as a criterion, namely the characteristic of very obvious phase asymmetry among the sum of all-network capacitance currents flowing in a grounding phase of a fault line, the non-grounding phase of the line and the capacitance current of a principal phase is adopted, so that the defect of measuring the precision of the measured value of the zero-sequence electric quantity is avoided theoretically, and the relay characteristic of the action performance is obviously better; the problems of single-phase earth fault detection and line selection protection of a small-current grounding system are one of difficulties in fault handling in the power distribution field, and the traditional method relies on zero-sequence electric quantity measurement precision and is easy to interfere. Disclosure of Invention Therefore, the invention aims to solve the technical problems of single-phase grounding fault detection and line selection protection of a small-current grounding system. The technical problem is solved by the following technical scheme that the invention provides a phase asymmetry principle line selection method, which comprises the step of realizing fault line identification by utilizing phase asymmetry and symmetry difference characteristics of a fault line and a sound line when a single-phase earth fault occurs and a fault line non-fault phase appears on a three-phase current abrupt change. In a preferred implementation mode of the phase asymmetry principle line selection method, three-phase current sampling values of all lines of a power distribution network are collected, three-phase current abrupt change values of all lines are calculated, and the maximum value, the middle value and the minimum value in the three-phase abrupt change values of all sampling points are determined according to the three-phase current abrupt change values. In a preferred embodiment of the phase asymmetry principle line selection method, if the three-phase current abrupt change of a certain line shows phase asymmetry characteristics and meets a preset criterion condition, the line is judged to be a single-phase ground fault line, and if the three-phase current abrupt change of the certain line shows relative characteristics, the line is judged to be a sound line. In a preferred embodiment of the phase asymmetry principle line selection method of the invention, the criterion condition comprises instantaneous asymmetry criterion for a single sampling point, and the instantaneous asymmetry criterion formula comprises maxΔip(k)≥Δiset;maxΔip(k)≥k1×minΔip(k）;maxΔip(k)-midΔip(k)≥k2×(midΔip(k)-minΔip(k)）;midΔip(k)≤k3×minΔip(k）; Wherein, the 、、Respectively are sampling pointsThree-phase current abrupt change maximum, intermediate and minimum values; The phase current abrupt change is the minimum value; 、、 is an asymmetry coefficient. In a preferred embodiment of the phase asymmetry principle line selection method, the criterion condition further comprises an overall asymmetry criterion for the data window, wherein the overall asymmetry criterion needs to be satisfied: maxΔip≥k1×minΔip; Wherein max delta i p is the maximum value of the periodic mutation amount screened by the phase with the largest mutation amount in the data window, and min delta i p is the maximum value of the periodic mutation amount screened by the phase with the smallest mutation amount in the data window. In a preferred embodiment of the phase asymmetry principle line selection method, the three-phase current mutation quantity of each line is calculated, and particularly a periodic mutation quantity calculation formula is adopted, wherein delta ip (k) = |ip (k) -ip (k-N) | -ip (k-N) -ip (k-2N) |; Wherein, the Is thatPhase atThe amount of periodic abrupt change of the dot,Taking any one of A, B, C phases; Is that Phase atSampling a point current; The sampling point number is one power frequency cycle. In a preferred embodiment of the phase asymmetry principle line selection method, after the starting element captures the ground fault moment, a transient data window or a steady-state data window is intercepted, the number of sampling points meeting instantaneous asymmetry criteria is counted in the data window, and when the number of sampling points meeting the instantaneous asymmetry criteria exceeds a set threshold value and simultaneously meets the overall asymmetry criteria, the single-phase ground fault is identified. In a preferred embodiment of the phase asymmetry princ