CN114675213B - Fault identification method for distribution network transformer - Google Patents
Fault identification method for distribution network transformer Download PDFInfo
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- CN114675213B CN114675213B CN202210349070.2A CN202210349070A CN114675213B CN 114675213 B CN114675213 B CN 114675213B CN 202210349070 A CN202210349070 A CN 202210349070A CN 114675213 B CN114675213 B CN 114675213B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/62—Testing of transformers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/16—Spectrum analysis; Fourier analysis
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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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- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The invention provides a power distribution network transformer fault identification method which comprises the steps of obtaining outlet current and bus voltage of a power distribution network transformer, and calculating current characteristic components of the outlet current and voltage characteristic components of the bus voltage through a digital signal processing algorithm; respectively calculating total harmonic distortion parameters for evaluating the power quality according to the current characteristic component of the outlet current and the voltage characteristic component of the bus voltage; respectively calculating single harmonic distortion parameters according to the current characteristic components and the voltage characteristic components; and calculating a current harmonic distortion factor and a voltage harmonic distortion factor, judging the relation between the distortion factors and a harmonic stability threshold value, and determining whether the distribution network transformer has a fault. The invention solves the problem of inaccurate fault analysis of distribution network transformers due to harmonic factors.
Description
Technical Field
The invention relates to the technical field of power distribution automation of a power system, in particular to a fault identification method in power distribution management.
Background
With the development of socio-economic, the expectation of electricity services is gradually increased. A major factor affecting electrical service is power failure. In a new power system innovation, how to quickly study and judge power faults has important significance on ensuring continuous and reliable power supply and reducing power failure time in order to comprehensively realize 'reserve capacity and amplification capacity' in market competition.
The power distribution network faults comprise equipment breakdown caused by voltage and current and the like, equipment temperature rise caused by the phase-off operation of a transformer, insulation capacity reduction, short circuit, single-phase earth fault, open circuit fault and the like. Harmonic factors in the operation process of the power distribution network are important factors causing the fault problem of the power distribution network, and can cause transformer overheating and aging, line overload, abnormal operation of a protection system and motor heat effect, so that the safe operation of the power distribution network is seriously threatened, and therefore, the fault analysis of the power distribution network based on the harmonic waves is the current key point.
However, in the prior art, the transformer fault analysis for harmonic waves includes calculating harmonic wave data by using historical electric energy data and predicting by using an algorithm, or setting a harmonic wave judgment rule to determine a mapping relation by combining the electric energy analysis data so as to determine a fault point, and the accuracy and efficiency of the two judgment modes are still low, the data volume requirement is high, and the error judgment caused by the two judgment modes can greatly influence the emergency repair efficiency of electric power personnel.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a fault identification method for a distribution network transformer.
The invention is realized by the following technical scheme:
step S1: the distribution network monitoring terminal acquires outlet current and bus voltage of a distribution network transformer, and calculates current characteristic components of the outlet current and voltage characteristic components of the bus voltage through a digital signal processing algorithm;
step S2: respectively calculating total harmonic distortion parameters for evaluating the quality of electric energy according to the current characteristic component of the outlet current and the voltage characteristic component of the bus voltage, wherein the total harmonic distortion parameters comprise a current total harmonic distortion parameter corresponding to the current characteristic component and a voltage total harmonic distortion parameter corresponding to the voltage characteristic component;
and step S3: respectively calculating single harmonic distortion parameters according to the current characteristic component and the voltage characteristic component, wherein the single harmonic distortion parameters comprise a current single harmonic distortion parameter corresponding to the current characteristic component and a voltage single harmonic distortion parameter corresponding to the voltage characteristic component;
and step S4: calculating a current harmonic distortion factor according to the current single harmonic distortion parameter and the current total harmonic distortion parameter, calculating a voltage harmonic distortion factor according to the voltage single harmonic distortion parameter and the voltage total harmonic distortion parameter, judging the relation between the distortion factor and a harmonic stability threshold value, determining whether the power distribution network transformer has a fault, and if the power distribution network transformer has the fault, sending early warning information by a power distribution network monitoring terminal.
Compared with the prior art, the invention has the beneficial effects that:
in the fault analysis process of the power distribution network transformer, the amplitude and the phase angle of the transformer harmonic current during injection are considered, when the harmonic current is injected, harmonic distortion parameters are jointly calculated based on the harmonic current superposed on the fundamental current, and whether the transformer has a fault caused by harmonic factors or not is determined based on the harmonic distortion parameters. The accuracy of harmonic judgment of distribution network transformer faults is effectively improved, and the data volume and the operation amount are reduced.
Drawings
FIG. 1 is a structural framework for fault determination of a power distribution network of the present invention;
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1, an embodiment of the present invention provides a method for identifying a fault of a transformer in a power distribution network, where the method includes:
step S1: the distribution network monitoring terminal acquires outlet current and bus voltage of a distribution network transformer, and calculates current characteristic components of the outlet current and voltage characteristic components of the bus voltage through a digital signal processing algorithm;
step S2: respectively calculating total harmonic distortion parameters for evaluating the quality of electric energy according to the current characteristic component of the outlet current and the voltage characteristic component of the bus voltage, wherein the total harmonic distortion parameters comprise a current total harmonic distortion parameter corresponding to the current characteristic component and a voltage total harmonic distortion parameter corresponding to the voltage characteristic component;
and step S3: respectively calculating single harmonic distortion parameters according to the current characteristic component and the voltage characteristic component, wherein the single harmonic distortion parameters comprise a current single harmonic distortion parameter corresponding to the current characteristic component and a voltage single harmonic distortion parameter corresponding to the voltage characteristic component;
and step S4: calculating a current harmonic distortion factor according to the current single harmonic distortion parameter and the current total harmonic distortion parameter, calculating a voltage harmonic distortion factor according to the voltage single harmonic distortion parameter and the voltage total harmonic distortion parameter, judging the relation between the distortion factor and a harmonic stability threshold value, determining whether a power distribution network transformer fails, and if the power distribution network transformer fails, sending early warning information by a power distribution network monitoring terminal.
Further, a current characteristic component I of the outlet current d The calculation method comprises the following steps:
a voltage characteristic component U of the bus voltage d The calculation method comprises the following steps:
wherein, I i Amplitude of current, U i Is the voltage amplitude, i is the harmonic order, ω 0 Is the fundamental angular frequency, θ i Is the phase angle of the current and is,
is the voltage phase angle
The current total harmonic distortion parameter I thd The calculation method comprises the following steps:
the voltage total harmonic distortion parameter U thd The calculation method comprises the following steps:
the current single harmonic distortion parameter I' thd The calculation method comprises the following steps:
I′ thd ＝I i /I d
the voltage single harmonic distortion parameter U' thd The calculation method comprises the following steps:
U′ thd ＝U i /U d
preferably, the digital signal processing algorithm is a fast discrete fourier algorithm.
Further, the determining the relationship between the distortion factor and the harmonic stability threshold to determine whether the distribution network transformer fails specifically includes:
current harmonic distortion factor alpha thd Expressed as:
α thd ＝I′ thd /I thd
voltage harmonic distortion factor beta thd Expressed as:
β thd ＝U′ thd /U thd
when the current harmonic distortion factor alpha thd Greater than or equal to a current harmonic stability threshold, and the voltage harmonic distortion factor beta thd When the voltage harmonic wave stability threshold value is larger than or equal to the voltage harmonic wave stability threshold value, the distribution network transformer is not abnormal; otherwise, the distribution network monitoring terminal sends out early warning information.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience of description and simplification of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
Finally, it should be noted that the above-mentioned technical solution is only one embodiment of the present invention, and it will be apparent to those skilled in the art that various modifications and variations can be easily made based on the application method and principle of the present invention disclosed, and the method is not limited to the above-mentioned specific embodiment of the present invention, so that the above-mentioned embodiment is only preferred, and not restrictive.
Claims (3)
1. A distribution network transformer fault identification method is characterized by comprising the following steps:
step S1: the distribution network monitoring terminal obtains the outlet current and the bus voltage of the distribution network transformer, and the current characteristic component I of the outlet current is calculated through a digital signal processing algorithm d And a voltage characteristic component U of the bus voltage d ；
A current characteristic component I of the outlet current d Expressed as:
a voltage characteristic component U of the bus voltage d Is expressed as:
wherein, I i Amplitude of current, U i Is the voltage amplitude, i is the harmonic order, ω 0 Is the fundamental angular frequency, θ i Is the phase angle of the current (in the case of a phase-locked loop),
is the voltage phase angle
Step S2: respectively calculating total harmonic distortion parameters for evaluating the power quality according to the current characteristic components of the outlet current and the voltage characteristic components of the bus voltage, wherein the total harmonic distortion parameters comprise current total harmonic distortion parameters I corresponding to the current characteristic components thd And a voltage total harmonic distortion parameter U corresponding to the voltage characteristic component thd ；
The current total harmonic distortion parameter I thd Expressed as:
the voltage total harmonic distortion parameter U thd Expressed as:
and step S3: respectively calculating single harmonic distortion parameters according to the current characteristic component and the voltage characteristic component, wherein the single harmonic distortion parameters comprise current single harmonic distortion parameters I 'corresponding to the current characteristic component' thd And a voltage single harmonic distortion parameter U 'corresponding to the voltage characteristic component' thd ；
The current single harmonic distortion parameter I' thd Expressed as:
I′ thd ＝I i /I d
the voltage single harmonic distortion parameter U' thd Expressed as:
U′ thd ＝U i /U d
and step S4: calculating a current harmonic distortion factor alpha according to the current single harmonic distortion parameter and the current total harmonic distortion parameter thd Calculating a voltage harmonic distortion factor beta according to the voltage single harmonic distortion parameter and the voltage total harmonic distortion parameter thd And judging the relation between the distortion factor and the harmonic stability threshold value, determining whether the distribution network transformer has a fault, and if the distribution network transformer has the fault, sending early warning information by the distribution network monitoring terminal.
2. The distribution network transformer fault identification method of claim 1, wherein: the digital signal processing algorithm is a fast discrete Fourier algorithm.
3. The distribution network transformer fault identification method of claim 1, wherein: the step of judging the relation between the distortion factor and the harmonic wave stability threshold value and determining whether the power distribution network transformer has a fault specifically comprises the following steps:
current harmonic distortion factor alpha thd Expressed as:
α thd ＝I′ thd /I thd
voltage harmonic distortion factorβ thd Expressed as:
β thd ＝U′ thd /U thd
when the current harmonic distortion factor alpha thd Greater than or equal to a current harmonic stability threshold, and the voltage harmonic distortion factor beta thd When the voltage harmonic wave stability threshold value is larger than or equal to the voltage harmonic wave stability threshold value, the distribution network transformer is not abnormal; otherwise, the distribution network monitoring terminal sends out early warning information.
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| CN111525572A (en) * | 2020-05-19 | 2020-08-11 | 中铁电气化局集团有限公司 | Method, device, equipment and storage medium for determining power quality grade in power grid |
| CN112485523A (en) * | 2020-11-25 | 2021-03-12 | 云南电网有限责任公司电力科学研究院 | Method for judging harmonic voltage measurement distortion |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103890594A (en) * | 2011-10-19 | 2014-06-25 | 施耐德电器工业公司 | Method and device for analysing the quality of the electrical energy in a three-phase electric network |
| KR101362740B1 (en) * | 2012-12-20 | 2014-02-24 | 현대오트론 주식회사 | Method for monitoring of fuel cell stack status |
| CN111525572A (en) * | 2020-05-19 | 2020-08-11 | 中铁电气化局集团有限公司 | Method, device, equipment and storage medium for determining power quality grade in power grid |
| WO2021233347A1 (en) * | 2020-05-19 | 2021-11-25 | 中铁电气化局集团有限公司 | Power quality grade determination method and apparatus in power grid, device and storage medium |
| CN111458652A (en) * | 2020-06-10 | 2020-07-28 | 南方电网科学研究院有限责任公司 | Fault determination method, device and equipment for direct current charging pile |
| CN112485523A (en) * | 2020-11-25 | 2021-03-12 | 云南电网有限责任公司电力科学研究院 | Method for judging harmonic voltage measurement distortion |
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