CN116646892B - Implementation method of small-current grounding line selection self-adaptive return coefficient - Google Patents
Implementation method of small-current grounding line selection self-adaptive return coefficient Download PDFInfo
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- CN116646892B CN116646892B CN202310912741.6A CN202310912741A CN116646892B CN 116646892 B CN116646892 B CN 116646892B CN 202310912741 A CN202310912741 A CN 202310912741A CN 116646892 B CN116646892 B CN 116646892B
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/006—Calibration or setting of parameters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
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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
Abstract
The invention belongs to the technical field of grounding line selection protection of a low-current grounding power system, and particularly relates to a method for realizing a self-adaptive return coefficient of the low-current grounding line selection. The invention adopts a strategy of self-adaptive return coefficient, solves the problem that the return coefficient is not corresponding to the return coefficient after the single-phase ground fault disappears and can not return, or the problem that the return coefficient is not corresponding to the return coefficient after the single-phase ground fault does not disappear and returns in advance, and prevents the malfunction, refusal or abnormality of the line selection protection of the low-current grounding system due to the return coefficient when the single-phase ground fault occurs in the low-current grounding power system.
Description
Technical Field
The invention belongs to the technical field of grounding line selection protection of a low-current grounding power system, and particularly relates to a method for realizing a self-adaptive return coefficient of the low-current grounding line selection.
Background
The small-current grounding power system has single-phase grounding faults, the fault types are quite rich, and the grounding current span is quite large and is from tens of milliamperes to nearly kiloamperes. The fixed setting return coefficient in the low-current grounding power system often cannot meet the actual requirements, and the situations of setting a small action fixed value, high-resistance single-phase grounding faults and loads occur, so that the return coefficient is low and cannot return; or setting a large action fixed value, a high-resistance single-phase grounding fault and a load, and leading the return coefficient to be high and return in advance. The return coefficient is the ratio of the action return value to the action constant value. Based on the above, a method for realizing the adaptive return coefficient of the low-current grounding line selection is needed.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention provides a method for realizing a small-current grounding line selection self-adaptive return coefficient.
The technical scheme for solving the technical problems is as follows:
the invention provides a realization method of a small-current grounding line selection self-adaptive return coefficient, which comprises the following steps:
when a single-phase grounding fault occurs in the low-current grounding power system, three-phase current is obtained according to a preset period, and the phase current abrupt change is calculated in real time by adopting the three-phase current;
calculating a self-adaptive return coefficient limit value curve variable according to the minimum value of the phase current mutation quantity, and obtaining a return coefficient of practical application; the method specifically comprises the following steps:
acquiring a fixed setting return coefficient in a low-current grounding power system, and presetting a phase current abrupt change quantity threshold, wherein the phase current abrupt change quantity threshold comprises a phase current abrupt change quantity first thresholdx 1 Second threshold value of phase current abrupt quantityx 2 Third threshold value of phase current abrupt quantityx 3 And meet the followingComparing the minimum constant value of the phase current abrupt change quantity with a preset phase current abrupt change quantity threshold value, and calculating to obtain a self-adaptive return coefficient limit value curve variable according to a comparison result;
when the minimum constant value of the phase current abrupt change quantity is smaller than or equal to the third threshold value of the phase current abrupt change quantity, if the calculated value of the self-adaptive return coefficient limit value curve variable is smaller than or equal to the setting return coefficient, the actually applied return coefficient is the setting return coefficient; if the calculated value of the self-adaptive return coefficient limit value curve is higher than the set return coefficient, the return coefficient actually applied is the self-adaptive return coefficient limit value curve variable;
when the minimum constant value of the phase current abrupt change quantity is larger than the third threshold value of the phase current abrupt change quantity, if the calculated self-adaptive return coefficient limit value curve variable is larger than or equal to the setting return coefficient, the actually applied return coefficient is the setting return coefficient; and if the calculated self-adaptive return coefficient limit value curve variable is smaller than the set return coefficient, the return coefficient actually applied is the self-adaptive return coefficient limit value curve variable.
Further, comparing the minimum constant value of the phase current abrupt change value with a preset phase current abrupt change value threshold, and calculating to obtain an adaptive return coefficient limit value curve variable according to a comparison result, wherein the adaptive return coefficient limit value curve variable specifically comprises:
wherein y is the adaptive return coefficient limit curve variable,xis the minimum constant value of the phase current abrupt quantity,x 1 for the phase current abrupt amount first threshold,x 2 for the phase current abrupt amount second threshold,x 3 and a third threshold value for phase current abrupt amount.
Further, three-phase current is adopted to calculate phase current abrupt change in real time, and the method specifically comprises the following steps:
wherein ,as the amount of phase current abrupt change,kas for the current sample point,pfor the same, N is the number of sampling points in each power frequency period, +.>Is the present sampled value of the phase current.
Compared with the prior art, the invention has the following technical effects:
the invention adopts a strategy of self-adaptive return coefficient, solves the problem that the return coefficient is not corresponding to the return coefficient after the single-phase ground fault disappears and can not return, or the problem that the return coefficient is not corresponding to the return coefficient after the single-phase ground fault disappears and returns in advance, and prevents malfunction, refusal or abnormality of the line selection protection of the low-current ground system due to the return coefficient when the single-phase ground fault occurs in the low-current ground power system.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions and advantages of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are only some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of the present invention.
Detailed Description
In order to further describe the technical means and effects adopted by the present invention to achieve the preset purpose, the following detailed description is given below of the specific implementation, structure, features and effects of the technical solution according to the present invention with reference to the accompanying drawings and preferred embodiments. The particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
The invention provides a method for realizing a small-current grounding line selection self-adaptive return coefficient, which is mainly used for a line selection protection device of a distributed small-current grounding system based on a three-phase current abrupt phase asymmetry principle (PAM principle, phase Asymmetry Method) and solves the problem that the return coefficient is not corresponding under various single-phase grounding fault scenes of the small-current grounding power system.
Referring to fig. 1, in an embodiment of the present invention, a method for implementing a small current grounding line selection adaptive return coefficient is provided, which mainly includes the following steps:
and step 1, when a single-phase grounding fault occurs in the low-current grounding power system, acquiring three-phase current according to a preset period, and calculating the phase current mutation quantity in real time by adopting the three-phase current.
In this embodiment, the phase current abrupt amount is:
wherein ,as the amount of phase current abrupt change,kas for the current sample point,pfor the same, N is the number of sampling points in each power frequency period, +.>Is the present sampled value of the phase current.
Step 2, according to the minimum value of the phase current abrupt change quantityxThe magnitude of the self-adaptive return coefficient limit value curve variable y is calculated, and the return coefficient of practical application is obtained。
Obtaining fixed setting return coefficient in small-current grounding power systemkPresetting a phase current abrupt change amount threshold, wherein the phase current abrupt change amount threshold comprises a phase current abrupt change amount first thresholdx 1 Second threshold value of phase current abrupt quantityx 2 Third threshold value of phase current abrupt quantityx 3 And meet the followingMinimum value of phase current abrupt changexComparing with a preset phase current mutation threshold value, calculating an adaptive return coefficient limit value curve variable y, wherein the return coefficient is setkA value of 0.60 to 0.98.
In the embodiment, the adaptive return coefficient limit curve variable y and the phase current abrupt change amount minimum constant valuexThe relation of (2) is:
wherein y is the adaptive return coefficient limit curve variable,xis the minimum constant value of the phase current abrupt quantity,x 1 for the phase current abrupt amount first threshold,x 2 for the phase current abrupt amount second threshold,x 3 and a third threshold value for phase current abrupt amount.
When the phase current abrupt change is minimumxLess than or equal to a third threshold value of phase current abrupt quantityx 3 If the calculated value of the variable y of the adaptive return coefficient limit value curve is less than or equal to the set return coefficientkReturn coefficient of actual applicationTo adjust the return coefficientkI.e. +.>The method comprises the steps of carrying out a first treatment on the surface of the If the calculated variable y value of the limit value curve of the self-adaptive return coefficient is higher than the setting return coefficientkWhen in use, the return coefficient of the actual application is +.>For adaptive return coefficient limit curve variable y, i.e.>。
When the phase current abrupt change is minimumxGreater than a third threshold value of phase current abrupt quantityx 3 When the calculated self-adaptive return coefficient limit value curve variable y is greater than or equal to the set return coefficient k, the return coefficient of actual applicationTo adjust the return coefficientkI.e. +.>The method comprises the steps of carrying out a first treatment on the surface of the If the calculated adaptive return coefficient limit value curve variable y is smaller than the wholeThe return coefficient k is determined, the return coefficient of actual application +.>For adaptive return coefficient limit curve variable y, i.e.>。
The invention obtains the actually applied return coefficient k' by utilizing the self-adaptive strategy in real time, thus calculating the action return value, namely, the action return value is equal to the setting action value multiplied by the actually applied return coefficient, and the setting action value is the minimum fixed value of the phase current mutation quantity in the embodiment, so that the problem that the return coefficient cannot return due to non-correspondence after the single-phase ground fault disappears, or the problem that the return coefficient does not correspond to the single-phase ground fault and returns in advance is solved.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (3)
1. The implementation method of the small-current grounding line selection self-adaptive return coefficient is characterized by comprising the following steps of:
when a single-phase grounding fault occurs in the low-current grounding power system, three-phase current is obtained according to a preset period, and the phase current abrupt change is calculated in real time by adopting the three-phase current;
calculating a self-adaptive return coefficient limit value curve variable according to the minimum value of the phase current mutation quantity, and obtaining a return coefficient of practical application; the method specifically comprises the following steps:
acquiring a fixed setting return coefficient in a low-current grounding power system, presetting a phase current abrupt change quantity threshold value, and obtaining the phase electricityThe threshold value of the current abrupt change amount comprises a first threshold value of the phase current abrupt change amountx 1 Second threshold value of phase current abrupt quantityx 2 Third threshold value of phase current abrupt quantityx 3 And meet the followingComparing the minimum constant value of the phase current abrupt change quantity with a preset phase current abrupt change quantity threshold value, and calculating to obtain a self-adaptive return coefficient limit value curve variable according to a comparison result;
when the minimum constant value of the phase current abrupt change quantity is smaller than or equal to the third threshold value of the phase current abrupt change quantity, if the calculated value of the self-adaptive return coefficient limit value curve variable is smaller than or equal to the setting return coefficient, the actually applied return coefficient is the setting return coefficient; if the calculated value of the self-adaptive return coefficient limit value curve is higher than the set return coefficient, the return coefficient actually applied is the self-adaptive return coefficient limit value curve variable;
when the minimum constant value of the phase current abrupt change quantity is larger than the third threshold value of the phase current abrupt change quantity, if the calculated self-adaptive return coefficient limit value curve variable is larger than or equal to the setting return coefficient, the actually applied return coefficient is the setting return coefficient; and if the calculated self-adaptive return coefficient limit value curve variable is smaller than the set return coefficient, the return coefficient actually applied is the self-adaptive return coefficient limit value curve variable.
2. The method for realizing the adaptive return coefficient of the low-current grounding line selection according to claim 1, wherein the method is characterized in that a minimum constant value of the phase current abrupt change value is compared with a preset phase current abrupt change value threshold, and the adaptive return coefficient limit value curve variable is calculated according to a comparison result, and specifically comprises the following steps:
wherein y is the adaptive return coefficient limit curve variable,xis the minimum constant value of the phase current abrupt quantity,x 1 first threshold value for phase current abrupt quantity，x 2 For the phase current abrupt amount second threshold,x 3 and a third threshold value for phase current abrupt amount.
3. The method for realizing the small-current grounding line selection self-adaptive return coefficient according to claim 1, wherein three-phase current is adopted to calculate the phase current abrupt change in real time, and the method is specifically as follows:
wherein ,as the amount of phase current abrupt change,kas for the current sample point,pfor the same, N is the number of sampling points in each power frequency period, +.>Is the present sampled value of the phase current.
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| US5825170A (en) * | 1997-01-24 | 1998-10-20 | Filtre-Expert | Magnetically coupled alternating stray current neutralizing method and system |
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| US9136692B2 (en) * | 2013-06-11 | 2015-09-15 | Electrical Materials Company | Low fault current isolator system |
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| US5825170A (en) * | 1997-01-24 | 1998-10-20 | Filtre-Expert | Magnetically coupled alternating stray current neutralizing method and system |
| JP2004147419A (en) * | 2002-10-23 | 2004-05-20 | B Ii Denshi Kogyo Kk | Power supply noise detecting and displaying arrangement |
| WO2015180529A1 (en) * | 2014-05-27 | 2015-12-03 | 国家电网公司 | Microgrid adaptive overcurrent protection method |
| CN107064741A (en) * | 2017-04-06 | 2017-08-18 | 广西电网有限责任公司电力科学研究院 | A kind of 2 points of successive ground fault line selecting methods of distribution network line different name phase |
| CN113629673A (en) * | 2021-09-14 | 2021-11-09 | 上海山源电子科技股份有限公司 | Relay protection fixed value updating method and device and computer readable storage medium |
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