CN102768325B - Fault location method for low-current grounding system - Google Patents

Fault location method for low-current grounding system Download PDF

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Publication number
CN102768325B
CN102768325B CN201210215865.0A CN201210215865A CN102768325B CN 102768325 B CN102768325 B CN 102768325B CN 201210215865 A CN201210215865 A CN 201210215865A CN 102768325 B CN102768325 B CN 102768325B
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China
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current
fault
voltage
place
grounding system
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Expired - Fee Related
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CN201210215865.0A
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Chinese (zh)
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CN102768325A (en
Inventor
徐振宇
李程
樊征臻
王萍萍
苏志鹏
杨政
傅锦发
高锐
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North China Electric Power University
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North China Electric Power University
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

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  • Locating Faults (AREA)

Abstract

The invention discloses a fault location method for a low-current grounding system in the technical field of power system fault location technology. The fault location method for the low-current grounding system includes measuring voltage and current at protection installation first; obtaining a fault point voltage expression; measuring current abrupt change of a capacitor; obtaining a relation expression of the current abrupt change and fault point voltage according to the abrupt change of the capacitor and the fault point voltage expression, and finally obtaining location of a ground fault. According to the characteristic that distribution lines distribute capacitive current, the location of the ground fault of the low-current grounding system is measured, the fault location can be determined in a short time after fault, power supply can be restored as soon as possible, and power supply reliability is improved.

Description

A kind of low current neutral grounding system fault distance-finding method
Technical field
The invention belongs to electric power system fault ranging technology field, relate in particular to a kind of low current neutral grounding system fault distance-finding method.
Background technology
Small current neutral grounding system line fault location is a century difficult problem, due to distribution lines a large amount of in system, the probability that earth fault occurs is very large, but up to the present for small current neutral grounding system, can only accomplish selecting properly faulty line, can't accomplish correct measurement fault distance, once this is, because of the circuit for small current neutral grounding system, earth fault occurs, and almost there is no fault current, traditional Fault Locating Method cannot be determined fault distance.This just gives the correct looking up the fault point of field operator, eliminates in time potential faults, improves power supply reliability and has increased very large difficulty.The hidden fault of sometimes searching Yi Tiao supply line may need the time of several days.
Summary of the invention
For mentioning the deficiency that existing low current grounding cannot be determined fault distance in above-mentioned background technology, the present invention proposes a kind of low current neutral grounding system fault distance-finding method.
Technical scheme of the present invention is that a kind of low current neutral grounding system fault distance-finding method, is characterized in that the method comprises the following steps:
Step 1: the voltage and current of measuring and protecting installation place;
Step 2: the voltage expression formula that obtains place, trouble spot on the basis of step 1;
Step 3: the jump-value of current of measuring electric capacity;
Step 4: according to the voltage expression formula at the jump-value of current of electric capacity and trouble spot place, try to achieve the relational expression of the voltage at jump-value of current and place, trouble spot, and then the fault distance while trying to achieve earth fault.
The voltage expression formula at place, described trouble spot is:
Wherein:
U fvoltage for place, trouble spot;
voltage for protection installation place;
electric current for protection installation place;
Fault distance when x is earth fault;
Z 1for every kilometer of positive sequence impedance;
K is zero sequence compensation coefficient;
I ofor zero-sequence current.
The relational expression of the voltage at described jump-value of current and place, trouble spot is:
Wherein:
Δ I cjump-value of current for electric capacity;
Im () is the imaginary part of variable;
Re () is the real part of variable.
The computing formula of fault distance during described earth fault is:
The present invention proposes a kind of low current neutral grounding system fault distance-finding method.Utilize the feature of distribution line capacitance current to measure small current neutral grounding system earth fault distance, after breaking down, in extremely short time, just can determine fault distance, be beneficial to restore electricity as early as possible, raising power supply reliability.Test findings surface the inventive method has been eliminated load current and the impact of stake resistance on ground distance protection.
Accompanying drawing explanation
Fig. 1 is small current neutral grounding system ground path fault schematic diagram.
Embodiment
Below in conjunction with accompanying drawing, preferred embodiment is elaborated.Should be emphasized that, following explanation is only exemplary, rather than in order to limit the scope of the invention and to apply.
The present invention relates to the method for small current neutral grounding system localization of fault in field of power.Disclose earth fault positioning principle in a kind of small current neutral grounding system, fault distance all refers to that protection installation place is to the distance between trouble spot conventionally.Be that electric current and voltage amount measured place is to the distance between trouble spot.When distribution line of small-current grounding system generation earth fault, the electric current of (as shown in Figure 1) protection installation place is voltage is fault distance during earth fault is that x, voltage are U f, ground current is I f, protection records the jump-value of current Δ I of electric capacity c.Because be that fault is always ohmic, so there is U fand I fsame-phase; Because Δ I cand I fphasing degree is identical, so draw U fwith Δ I cphase angle is identical.
Δ I cand U fbecome plural form, because both phase angles are identical, obtain Δ I cimaginary part and the ratio of real part equal U fimaginary part and the ratio of real part, that is:
Calculate thus:
Because this equation itself is irrelevant with load current and stake resistance, the fault localization element while therefore can be used as distribution line of small-current grounding system generation earth fault.Theoretical analysis and simulation result all show that carried principle has very high practicality and computational accuracy.
As shown in Figure 1, so do not have the traditional method of fault current can not correct measurement fault distance for small current neutral grounding system trouble spot when there is earth fault.But the capacitance current of whole system can be flow through in trouble spot, utilize the synchronous principle of fault point voltage and electric current, can correct measurement low current neutral grounding system fault distance.According to the present invention, distribution line failure distance measuring equipment obtains electric current and voltage instantaneous value to the voltage current waveform sampling of mutual inductor, by fourier algorithm, obtains Δ I c, I odeng phasor form; Due to I f, U f, Δ I cphase angle identical, obtain and load current and the irrelevant fault distance of stake resistance:
Symbol in below discussing is used as follows: current transformer (being called for short TA, as follows) and voltage transformer (VT) (being called for short TV, as follows).
First protect according to the TA of protection installation place and the instantaneous value that TV records electric current and voltage.
Secondly by fourier algorithm, obtain the phasor form of each electric parameters, utilize following formula to obtain:
The above; be only the present invention's embodiment preferably, but protection scope of the present invention is not limited to this, is anyly familiar with in technical scope that those skilled in the art disclose in the present invention; the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.

Claims (1)

1. a low current neutral grounding system fault distance-finding method, is characterized in that the method comprises the following steps:
Step 1: the voltage and current of measuring and protecting installation place;
Step 2: the voltage expression formula that obtains place, trouble spot on the basis of step 1; The voltage expression formula at place, described trouble spot is:
Wherein:
U fvoltage for place, trouble spot;
voltage for protection installation place;
electric current for protection installation place;
Fault distance when x is earth fault;
Z 1for every kilometer of positive sequence impedance;
K is zero sequence compensation coefficient;
I 0for zero-sequence current;
Step 3: the jump-value of current of measuring electric capacity;
Step 4: according to the voltage expression formula at the jump-value of current of electric capacity and trouble spot place, try to achieve the relational expression of the voltage at jump-value of current and place, trouble spot, and then the fault distance while trying to achieve earth fault; The relational expression of the voltage at described jump-value of current and place, trouble spot is:
Wherein:
Δ I cjump-value of current for electric capacity;
Im () is the imaginary part of variable;
Re () is the real part of variable;
The computing formula of fault distance during described earth fault is:
CN201210215865.0A 2012-06-26 2012-06-26 Fault location method for low-current grounding system Expired - Fee Related CN102768325B (en)

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Application Number Priority Date Filing Date Title
CN201210215865.0A CN102768325B (en) 2012-06-26 2012-06-26 Fault location method for low-current grounding system

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Publication number Priority date Publication date Assignee Title
CN103116114B (en) * 2013-01-23 2015-08-19 中国南方电网有限责任公司超高压输电公司检修试验中心 Fault distance-finding method under a kind of DC de-icing device ground wire deicing pattern and system
CN103226175A (en) * 2013-03-21 2013-07-31 江苏省电力公司泰州供电公司 Method for achieving double-ended ranging by virtue of resistance characteristics of ground resistor
CN103245876B (en) * 2013-04-15 2015-08-26 国家电网公司 Voltage drop real part characteristic is utilized to realize circuit inter-phase fault single-end ranging
CN103293439B (en) * 2013-05-19 2015-12-02 国家电网公司 Based on distribution parameter measurement impedance magnitude characteristic line single-phase earth fault single-terminal location method
CN110470950B (en) * 2019-08-16 2021-07-16 深圳供电局有限公司 Fault location method for power transmission line

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CN101340086A (en) * 2008-01-21 2009-01-07 孙嘉宁 Single-phase grounding fault determining, protecting method and system of neutral-point uneffective earthed electric grid
CN101387682A (en) * 2008-10-27 2009-03-18 清华大学 Single-phase earth fault detecting method based on residual current harmonic component

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KR100473798B1 (en) * 2002-02-20 2005-03-08 명지대학교 Method for detecting line to ground fault location for power systems

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Publication number Priority date Publication date Assignee Title
CN101340086A (en) * 2008-01-21 2009-01-07 孙嘉宁 Single-phase grounding fault determining, protecting method and system of neutral-point uneffective earthed electric grid
CN101387682A (en) * 2008-10-27 2009-03-18 清华大学 Single-phase earth fault detecting method based on residual current harmonic component

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梁志瑞等.一种小电流接地系统单相接地故障测距新方法.《电力系统自动化》.2009,第33卷(第5期),

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Inventor after: Xu Zhenyu

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Free format text: CORRECT: INVENTOR; FROM: XU ZHENYU LI CHENG FAN ZHENGZHEN WANG PINGPING SU ZHIPENG YANG ZHENG FU JINFA GAO RUI TO: XU ZHENYU ZHANG JINHU XU TAO LI CHENG FAN ZHENGZHEN WANG PINGPING SU ZHIPENG YANG ZHENG FU JINFA GAO RUI

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