CN112595998A - Frequency response testing method based on transformer broadband model and application - Google Patents
Frequency response testing method based on transformer broadband model and application Download PDFInfo
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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
- G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
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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
- G01R31/003—Environmental or reliability tests
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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
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
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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
- G01R31/72—Testing of electric windings
Abstract
The invention relates to a frequency response test method based on a transformer broadband model and application thereof.A common-mode broadband circuit model of a transformer to be tested is formed by determining the number of layers of windings on two sides according to a winding structure of the transformer to be tested, each layer comprises a series structure formed by a winding inductor and a winding resistor, two ends of the series structure are grounded through a grounding capacitor and are connected with an inter-turn capacitor in parallel, the layers are connected through an interlayer capacitor, each capacitor is connected with the resistor in parallel, and winding mutual inductance exists between different layers; determining characteristic parameters of each component in the model; and calculating a frequency response curve based on the transformer broadband model. The model can more accurately represent the frequency variation characteristic in the wide frequency band of the electrical parameters, improve the accuracy of describing the change of the resonance point of the high frequency band caused by insulation aging or winding deformation, and more accurately explore the change rule of the wide frequency response test curve. The method can better serve for monitoring and evaluating the state of the power transformer based on the FRA method, can serve for detecting the aging state, and accurately evaluates the state difference before and after aging.
Description
Technical Field
The invention relates to the technical field of power transformer modeling, in particular to a frequency response testing method based on a transformer broadband model and application thereof.
Background
The good running state health of the power equipment is an important guarantee for the safe, stable and economic running of the power system. The failure rate of the power transformer, which is one of the most expensive power devices with the highest reliability level, greatly affects the reliability and economy of the operation of the power system. According to the statistical data of CIGRE WG A2.37, the total failure rate of the power transformer of the traditional power transmission and distribution system is about 1%.
In the operation process of the power transformer, short-time lightning overvoltage and short-circuit impact stress bring damages to a winding and an insulation system of the power transformer, such as winding deformation, insulation failure and the like. After the cumulative effect is taken into consideration, the service life of the power transformer is greatly reduced, and potential safety hazards are brought to a power system. Therefore, the further development of the internal defects of the power transformer into system-level major accidents is avoided, and a reliable operation state monitoring technology needs to be provided for the power transformer, so that preventive protection and comprehensive diagnosis are realized.
A Frequency Response Analysis (FRA) method is a technology widely used in engineering for monitoring the condition of power transformers. Generally, in a factory test or an overhaul inspection of a power transformer, a frequency spectrum scan of a wide frequency band is performed by using an impedance analyzer to obtain a frequency response test curve. And (3) testing when the transformer leaves the factory, wherein the insulation and winding states of the power transformer are healthy, and the measured frequency response curve is used as a reference. The frequency response curve measured at each overhaul check is the frequency response curve of the power transformer in the current state. The state of health of the power transformer is determined by comparing the reference curve with the curve, observing curve shift, change in resonance point, and the like. Generally, different winding insulation states inside the power transformer can be reflected on different frequency bands of the broadband test curve. However, the evaluation method is generally based on a great deal of experimental summary experience and graphic morphological change and is not universal. In other words, in the face of different monitoring transformers, the distribution rule of the broadband test curve changes, and the change rules of insulation aging and winding deformation at different positions on the broadband curve are different, so that the problem of monitoring and evaluating the state of the power transformer based on the frequency response test is solved.
The power transformer circuit model that services the FRA typically employs an N-ladder circuit model. FIG. 1(a) shows an N-ladder circuit model of a three-phase double-winding transformer, wherein the model is divided into N layers, and the same type of parameters in each layer are equal. The N-ladder circuit model can describe various insulation distributions along the double-sided winding and the inductive coupling effect between the coils of the double-sided winding. Taking the first layer as an example, the various types of insulation shown in fig. 1(b) include five types of insulation, namely primary side winding inter-turn insulation, primary side winding earth main insulation, primary/secondary side winding inter-turn insulation, secondary side winding inter-turn insulation and secondary side winding earth main insulation; referring to fig. 1(a), the inductive coupling effect includes three mutual inductance types of mutual inductance between coils of different layers of windings on the same side, mutual inductance between the same layers of windings on different sides, and mutual inductance between the different layers of windings on different sides.
Impedance characteristics of each capacitive element and each inductive element in the circuit model are different in a wide frequency band, and different resonance points are formed. When the mechanical characteristics of a certain position of the power transformer are changed or the insulation is aged, the corresponding capacitive element in the circuit model is increased, so that the broadband impedance of the circuit model is changed, the resonance point distribution of the overall response is influenced, and the insulation aging of the power transformer is monitored.
The N-ladder circuit model described in the prior art has the following disadvantages: 1) the same type of parameters in each layer are equal, and the method is only suitable for the condition that the windings on each side are of single-layer structures. When the power transformer winding is a multilayer structure, the various types of insulation branches distributed along the winding are no longer uniformly distributed, in relation to the interlayer structure. 2) The model does not contain the interlayer insulation of the windings on the same side. Integration 1) and 2), the model is not suitable for power transformers with multilayer winding structures. Furthermore, 3) the various electrical parameters within the prior art model are fixed and invariant constants. In other words, each parameter of the existing model does not account for the frequency-dependent characteristic, and the value of each parameter is considered to be independent of the frequency. In fact, the circuit parameters in fig. 1 are frequency-dependent over a wide frequency band, and if this characteristic is not taken into account, the description of the resonance point will deviate over a high frequency band. In addition, 4) the prior art generally describes a circuit model under differential mode excitation, and due to strong differential mode inductive coupling effect, mutual inductance parameters in the model are large and can be influenced by the magnetization characteristics of a power transformer core, so that the difficulty of parameterization on a wide frequency band is increased, and the monitoring of the insulation state of a transformer to be tested is not facilitated.
In summary, the N-ladder circuit model described in the prior art has several drawbacks, and the evaluation and analysis of the FRA monitoring results of the power transformer are still insufficient.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a frequency response test method based on a transformer broadband model and application thereof, provides a brand-new transformer broadband circuit model, fully considers the actual winding structure of a transformer to be tested and the broadband characteristics of various electrical parameters, serves the FRA method widely applied in engineering, provides a theoretical basis for monitoring the running state of a power transformer and provides the accuracy of frequency response calculation.
In order to achieve the above object, the present invention provides a frequency response testing method based on a transformer broadband model, comprising:
determining the number of layers of windings on two sides according to a winding structure of a transformer to be tested to form a common-mode broadband circuit model of the transformer to be tested, wherein each layer comprises a series structure formed by a winding inductor and a winding resistor, two ends of the series structure are grounded through a grounding capacitor and connected in parallel with an inter-turn capacitor, the layers are connected through an interlayer capacitor, each capacitor is connected in parallel with a resistor, and winding mutual inductance exists between different layers;
determining characteristic parameters of components of a common-mode wide-frequency circuit model of the transformer to be tested at each scanning frequency;
and calculating a frequency response curve based on the transformer broadband model.
Further, determining characteristic parameters of components of the common-mode broadband circuit model of the transformer to be tested at each scanning frequency includes:
measuring the winding inductance and the winding resistance of each side under the scanning frequency according to the winding conductor parameters of the two sides of the transformer to be measured, fitting to obtain the winding resistance and the winding inductance of each side under the continuous frequency spectrum, and calculating the winding resistance and the winding inductance of each layer;
according to structural parameters of windings on two sides of a transformer to be tested, a 2D electrostatic field single-phase model is constructed in simulation software, and ground capacitance, turn-to-turn capacitance and interlayer capacitance of each layer are obtained;
calculating the parallel resistance of each capacitor according to the dielectric loss factor under each scanning frequency;
according to the structural parameters of the windings on the two sides of the transformer to be measured, a 3D static magnetic field three-phase model is constructed in simulation software, common mode excitation is added, and the winding mutual inductance between layers under the scanning frequency is calculated.
Further, the fitting formula for obtaining the winding resistance and the winding inductance of each side under the continuous frequency spectrum by fitting is as follows:
FRi(f) denotes the winding resistance, FLi(f) Denotes a winding inductance, i denotes a primary winding when i is 1, denotes a secondary winding when i is 2, and aRi,bRi,aLi,bLi,cLiIs a fitting parameter, DiIs the length of the windings on both sides.
Further, according to the dielectric loss factor df (f) at each scanning frequency, the parallel resistance r (f) of each capacitor is calculated by the formula:
R(f)＝1/[2πf·C(f)·DF(f)]
where C (f) is the capacitance and f is the scanning frequency.
Further, calculating a frequency response curve based on the transformer broadband model, comprising:
in Simulink software, a transformer common-mode broadband circuit model is constructed, excitation under different scanning frequencies is given to solve the response, and a response curve is obtained.
The second aspect of the present invention provides a transformer state monitoring method, including:
determining the number of layers of windings on two sides according to a winding structure of a transformer to be tested to form a common-mode broadband circuit model of the transformer to be tested, wherein each layer comprises a series structure formed by a winding inductor and a winding resistor, two ends of the series structure are grounded through a grounding capacitor and connected in parallel with an inter-turn capacitor, the layers are connected through an interlayer capacitor, each capacitor is connected in parallel with a resistor, and winding mutual inductance exists between different layers; determining characteristic parameters of components of a common-mode wide-frequency circuit model of the transformer to be tested at each scanning frequency;
simulating various defects of the transformer in simulation software, changing characteristic parameters of various elements of the common-mode broadband circuit model, obtaining a frequency response curve under various defects, obtaining the amplitude of the frequency response curve under various defects and the variation rule of the deviation of the resonance point, and storing the amplitude and the deviation;
before the transformer to be tested is put into operation, detecting the frequency response under each scanning frequency to form a frequency response curve under the actual health condition;
after the transformer is put into operation, the frequency response curves of the transformer to be tested in actual operation at different time intervals are obtained and compared with the stored frequency response curves under actual health conditions, and the health state of the transformer is determined through curve movement and resonance point change.
Further, still include: under each scanning frequency point, comparing the frequency response curve in actual work at the current time period with the stored frequency response curve under the health condition of the testing transformer, calculating the deviation of the amplitude and the resonance point, comparing the deviation with the stored change rule when the deviation exceeds a deviation threshold value, and taking the defect type corresponding to the change rule with the amplitude and the resonance point deviation closest to each other as the defect of the to-be-tested transformer; and when the deviation does not exceed the deviation threshold, the state of the transformer to be tested is normal.
The third aspect of the present invention provides a method for detecting an aging state of a transformer, including:
obtaining and storing a frequency response curve of the transformer to be tested in a normal state by adopting the frequency response testing method based on the transformer broadband model;
detecting frequency response under each scanning frequency to form a frequency response curve under the actual health condition;
aging the transformer to be tested;
and testing the frequency response curve of the transformer to be tested in actual work, comparing the frequency response curve with the stored frequency response curve under the actual health condition, and determining the state after aging through curve movement and resonance point change.
Further, still include: simulating various defects of the transformer in simulation software, changing characteristic parameters of various elements of the common-mode broadband circuit model, obtaining a frequency response curve under various defects, and obtaining the amplitude of the frequency response curve under various defects and the variation rule of the deviation of a resonance point;
under each scanning frequency point, comparing a frequency response curve in actual work with a stored frequency response curve under an actual health condition, calculating the deviation of the amplitude and the resonance point, comparing the deviation with the change rule when the deviation exceeds a deviation threshold value, and taking the defect type corresponding to the change rule with the amplitude and the resonance point deviation closest as the defect of the transformer to be detected; and when the deviation does not exceed the deviation threshold, the state of the transformer to be tested is normal.
The invention provides a power equipment monitoring system in a fourth aspect, which comprises a first storage module, a detection module and a comparison module;
determining the number of layers of windings on two sides according to a winding structure of a transformer to be tested to form a common-mode broadband circuit model of the transformer to be tested, wherein each layer comprises a series structure formed by a winding inductor and a winding resistor, two ends of the series structure are grounded through a grounding capacitor and connected in parallel with an inter-turn capacitor, the layers are connected through an interlayer capacitor, each capacitor is connected in parallel with a resistor, and winding mutual inductance exists between different layers; determining characteristic parameters of components of a common-mode wide-frequency circuit model of the transformer to be tested at each scanning frequency; storing the common-mode broadband circuit model; in simulation software, changing each characteristic parameter of the common-mode broadband circuit model, simulating various defects of the transformer, and obtaining a frequency response curve under the various defects; obtaining the change rule of the amplitude of the frequency response curve and the deviation of the resonance point under various defects, and storing the change rule by the first storage module;
the detection module detects frequency response under each scanning frequency before the transformer to be detected is put into operation to form a frequency response curve under actual health conditions; detecting frequency response under each scanning frequency in the operation period of the transformer to be detected, forming a frequency response curve in actual operation, and storing the frequency response curves in the actual operation at different time periods;
the comparison module is used for comparing the frequency response curves stored by the detection module in different periods of actual work with the frequency response curves stored by the detection module under actual health conditions, calculating the deviation of the amplitude and the resonance point, comparing the deviation with the change rule stored by the first storage module when the deviation exceeds a deviation threshold value, and taking the defect type corresponding to the change rule with the amplitude and the resonance point closest to the deviation as the defect of the transformer to be detected; and when the deviation does not exceed the deviation threshold, the state of the transformer to be tested is normal.
The technical scheme of the invention has the following beneficial technical effects:
(1) the invention provides a brand-new transformer broadband model for a power transformer with a multilayer winding structure, takes account of interlayer insulation and non-uniform distribution characteristics between windings on the same side, more accurately characterizes the broadband characteristics of various electrical parameters in a circuit model, and improves the accuracy of describing the change of a high-frequency band resonance point caused by insulation aging or winding deformation. Compared with the traditional N-ladder model for monitoring and evaluating the state of the power transformer by the FRA method, the model has the advantages that the change rule of the broadband curve can be more accurately explored, and the condition monitoring and evaluation of the power transformer based on the FRA method can be better served.
(2) Aiming at a power transformer with a multilayer winding structure, a transformer broadband model accounts for interlayer insulation between windings on the same side, and the consideration is that various insulations are not uniformly distributed along the windings any more, namely the non-uniform distribution characteristic of each parameter of a circuit model is accounted according to the actual winding structure; the wide-frequency-band internal frequency variation characteristics of all elements in the circuit model are considered, namely the self resistance and inductance of the winding, various insulation capacitances and resistances and mutual inductance among different coils. Compared with the existing model constructed by non-frequency-variable parameters, the broadband characteristic in the broadband section of the electrical parameters can be more accurately represented, and the accuracy of describing the change of the resonance point of the high-frequency section caused by insulation aging or winding deformation is improved.
(3) The circuit model under the common mode is constructed, the strong inductive coupling effect caused by representing the iron core can be avoided, the influence of the magnetization characteristic of the iron core is further avoided, and the accuracy of describing the change of the high-frequency band resonance point caused by insulation aging is improved.
(4) The model can serve for an FRA method widely applied to engineering, provides a theoretical basis for monitoring the running state of the power transformer, and provides accuracy of frequency response calculation. The aging state detection can be served, and the state difference before and after aging can be accurately evaluated.
Drawings
FIG. 1 is a prior art N-ladder circuit model of a power transformer; wherein, the diagram (a) is an N-ladder circuit model of the three-phase double-winding transformer; FIG. b is a schematic diagram of various types of insulation;
FIG. 2 is a model of the wide-band common-mode circuit of the power transformer of the present invention;
FIG. 3 is a schematic diagram of a winding structure of a transformer in one embodiment;
FIG. 4 is a common-mode wide-band circuit model of the power transformer of the winding structure of the transformer of FIG. 3;
FIG. 5 is an example of a 2D electrostatic field single-phase model of power transformer Ansys/Maxwell simulation software; wherein (a) is calculating an interlayer capacitance model; (b) calculating a turn-to-turn capacitance model;
FIG. 6 is a schematic diagram of resistance parameters in an isolated parallel branch of a power transformer;
fig. 7 is a power transformer frequency response curve versus curve.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
The method is a theoretical basis for realizing the evaluation of the running state of the power transformer based on the FRA method. In order to obtain an accurate circuit model in a wide frequency band, the types of parameters in the model are determined according to the actual winding structure of a test transformer, the wide frequency band frequency variation characteristics of the circuit parameters are calculated, and finally the influence of the operation condition change on each parameter in the circuit model is considered. Based on the method, the change rule of the circuit model response under each working condition is explored by utilizing the actual measurable electrical quantity (voltage, current and the like), the monitoring and evaluation of the running state of the power transformer based on the FRA method can be served, the evaluation mode is not only dependent on the traditional empirical analysis and graphic analysis method, and the effective evaluation index can be obtained from a theoretical level.
Fig. 2 is a model of the wideband common mode circuit of the power transformer according to the present invention. For the sake of simplicity in representing various circuit parameters, the secondary side winding part is omitted in the figure. The primary side is taken as an example to illustrate various parameters of the model to which the present invention relates. Three types in total:
(1) the resistance and inductance of the transformer winding;
(2) the insulating parts comprise primary side winding turn-to-turn insulation, primary side winding earth main insulation, primary side winding interlayer insulation and primary/secondary side winding insulation. These four types of insulation are formed by parallel branches of capacitors and resistors.
(3) The mutual inductance between the windings of the layers is shown in dashed lines in fig. 2.
The primary side and the secondary side both use one side close to the inlet wire as a first layer, and sequentially comprise a second layer, a third layer and the like.
Based on the three parameters, as shown in fig. 2, each layer of the transformer common-mode wide-frequency circuit model provided by the invention comprises a series structure formed by a winding inductor and a winding resistor, wherein two ends of the series structure are grounded through a grounding capacitor and are connected with turn-to-turn capacitors in parallel, the layers are connected through interlayer capacitors, and all the capacitors are connected with the resistors in parallel.
The calculation process of the three types of parameters is as follows:
(1) and determining the number of layers of windings on two sides of the constructed model according to the winding structure of the transformer to be tested, and drawing the common-mode broadband circuit model of the power transformer to be tested based on the graph 2.
(2) And selecting winding conductor samples (unit length) on two sides of the transformer to be measured, and measuring the self resistance and inductance of the winding at a plurality of wide-band distributed frequencies f based on the RLC bridge. The conductor parameters of the continuous spectrum are fitted using the following empirical formula:
wherein, FRDenotes the winding resistance, FLRepresenting the winding inductance. When i is 1, the primary winding is indicated, and when i is 2, the secondary winding is indicated. a isRi,bRi,aLi,bLi,cLiIs a fitting parameter, DiIs the length of the windings on both sides.
After fitting, the resistance and inductance of each side winding at any frequency can be read. And the winding resistance and the inductance of each layer are obtained by equally dividing the winding resistance and the inductance on the side.
(3) According to the structure and physical size of a transformer winding to be measured, a 2D electrostatic field single-phase model (a cylindrical coordinate system) is constructed in Ansys/Maxwell simulation software, and all capacitance parameters representing insulation in the model are calculated.
(4) Given the dielectric loss factor df (f) at each scanning frequency f, all the parameters characterizing the resistance in the insulated parallel branches are calculated by the following formula:
R(f)＝1/[2πf·C(f)·DF(f)]. (2)
(5) according to the structure and physical size of a transformer winding to be measured, a 2D static magnetic field three-phase model (Cartesian coordinate system) is constructed in Ansys/Maxwell simulation software, and all mutual inductance parameters representing inductive coupling in the model are calculated. When the primary winding has N1Layer, secondary side winding has N2Layer, the inductance matrix calculated by Ansys/Maxwell simulation software is (3N)1+3N2)*(3N1+3N2) And (5) square matrix. Selection of all mutual inductive elements in common mode model (3N)1+3N2)*(3N1+3N2) Element E in a square matrixij，EijIs all the elements of the upper or lower triangle of the square matrix.
So far, the broadband parameterization results of all the elements in fig. 2 have been obtained.
Based on the transformer common-mode broadband circuit model, a frequency response test method is provided, and the method comprises the following steps:
(1) determining the number of layers of windings on two sides according to the winding structure of the transformer to be tested to form a common-mode broadband circuit model of the transformer to be tested, wherein each layer comprises a series structure formed by a winding inductor and a winding resistor, two ends of the series structure are grounded through a grounding capacitor and connected with an inter-turn capacitor in parallel, the layers are connected through an interlayer capacitor, and each capacitor is connected with a resistor in parallel.
(2) And determining characteristic parameters of each component of the common-mode broadband circuit model of the transformer to be tested under each scanning frequency.
(3) And calculating a frequency response curve of the transformer broadband model.
In Simulink software, a transformer common-mode broadband circuit model is constructed, excitation under different scanning frequencies is given to solve the response, and a response curve is obtained.
Further, based on the frequency response test method, a transformer state monitoring method is provided, which comprises the following steps:
(1) determining the number of layers of windings on two sides according to a winding structure of a transformer to be tested to form a common-mode broadband circuit model of the transformer to be tested, wherein each layer comprises a series structure formed by a winding inductor and a winding resistor, two ends of the series structure are grounded through a grounding capacitor and connected in parallel with an inter-turn capacitor, the layers are connected through an interlayer capacitor, each capacitor is connected in parallel with a resistor, and winding mutual inductance exists between different layers; determining characteristic parameters of components of a common-mode wide-frequency circuit model of the transformer to be tested at each scanning frequency;
(2) in simulation software, various defects of the transformer are simulated, characteristic parameters of various elements of the common-mode broadband circuit model are changed, a frequency response curve under various defects is obtained, and the amplitude of the frequency response curve under various defects and the change rule of the deviation of the resonance point are obtained and stored.
In Simulink software, for the construction of a transformer common-mode broadband circuit model, characteristic parameters of each element are changed to simulate various defects, and a frequency response curve under the condition of various defects is obtained. And obtaining the change rule of the amplitude of the frequency response curve and the deviation of the resonance point under various defects according to the frequency response curve.
(3) Before the transformer to be tested is put into operation, frequency responses under all scanning frequencies are detected to form a frequency response curve under the actual health condition.
(4) And obtaining frequency response curves of the transformer to be tested at different time intervals in the actual work, comparing the frequency response curve of the current time interval with the actual working frequency response curve under the healthy condition, calculating the deviation of the amplitude and the resonance point, and determining the health state of the transformer.
If the deviation of the amplitude from the resonance point does not exceed the corresponding threshold, the transformer is considered healthy. If the deviation exceeds the threshold value, the deviation is compared with the stored change rule, and the defect type corresponding to the change rule with the amplitude value closest to the deviation of the resonance point is used as the defect of the transformer to be detected.
The transformer state monitoring method can be realized by a power equipment monitoring system, and the invention further provides a power equipment monitoring system which comprises a first storage module, a detection module and a comparison module.
Simulating various defects of the transformer in simulation software, changing characteristic parameters of various elements of the common-mode broadband circuit model, and obtaining frequency response curves under various defects; obtaining the change rule of the amplitude of the frequency response curve and the deviation of the resonance point under various defects, and storing the change rule by the first storage module;
the detection module detects frequency response under each scanning frequency before the transformer to be detected is put into operation to form a frequency response curve under actual health conditions; detecting frequency response under each scanning frequency in the running life of the transformer to be detected to form a frequency response curve in actual work; storing frequency response curves in actual operation at different time periods;
the comparison module is used for comparing the frequency response curves stored by the detection module in different periods of actual work with the frequency response curves stored by the detection module under actual health conditions, calculating the deviation of the amplitude and the resonance point, comparing the deviation with the change rule stored by the first storage module when the deviation exceeds a deviation threshold value, and taking the defect type corresponding to the change rule with the amplitude and the resonance point closest to the deviation as the defect of the transformer to be detected; and when the deviation does not exceed the deviation threshold, the state of the transformer to be tested is normal.
Further, the frequency response test method can be applied to detection of the aging state of the transformer. The invention provides a transformer aging state detection method, which comprises the following steps:
(1) and obtaining and storing a frequency response curve of the transformer to be tested in a normal state by adopting the frequency response testing method based on the transformer broadband model.
(2) In simulation software, various defects of the transformer are simulated, characteristic parameters of various elements of the common-mode broadband circuit model are changed, and frequency response curves under various defects are obtained.
In Simulink software, a transformer common-mode broadband circuit model is constructed, characteristic parameters of each element are changed to simulate various defects, a frequency response curve under various defects is obtained, and the change rule of the amplitude of the frequency response curve and the deviation of a resonance point under various defects is obtained.
(3) And detecting the frequency response under each scanning frequency, forming and storing a frequency response curve under the actual health condition.
(4) And aging the transformer to be tested. The aging experiment was performed using the existing aging method.
(5) And testing the frequency response curve of the transformer to be tested in actual work, comparing the frequency response curve with the stored frequency response curve under the actual health condition, and determining the state after aging through curve movement and resonance point change.
Under each scanning frequency point, comparing a frequency response curve in actual work with a stored frequency response curve in a normal state, calculating the deviation of the amplitude and the resonance point, comparing the frequency response curve in actual work with the frequency response curves under various defects when the deviation exceeds a deviation threshold value, and taking the defect corresponding to the frequency response curve under the defect with the amplitude closest to the resonance point as the defect of the transformer to be detected; and when the deviation does not exceed the deviation threshold, the transformer to be tested is normal.
Examples
In order to show the calculation method of each circuit parameter in the power transformer common-mode broadband circuit model in detail, a three-phase double-winding power transformer is taken as an example, the winding structure of the power transformer is shown in fig. 3, and the physical size of the winding is shown in table 1.
Table 1 example winding physical dimensions of transformers
| Primary side | Secondary side | |
| Number of winding |
1 | 1 |
| Number of turns | 108 | 63 |
| Number of |
3 | 2 |
| Thickness of wire | 5mm | 6mm |
| Width of wire | 1.6mm | 1.6mm |
| Thickness of external insulation of wire | 0.45mm | 0.45mm |
The calculation process of the three types of parameters is as follows:
(1) and determining the number of layers of windings on two sides of the constructed model according to the winding structure of the transformer to be tested, and drawing the topology of the common-mode broadband circuit model of the power transformer to be tested based on the graph 2, as shown in the graph 4.
(2) Selecting samples (unit length) of conductors of windings on two sides of the transformer, and measuring the self resistance F of the windings at a plurality of frequencies F distributed in a wide frequency band based on an RLC bridgeRi(f) And an inductance FLi(f) In that respect The conductor parameters of the continuous spectrum are fitted using the following empirical formula:
wherein, aR1＝0.00167,bR1＝0.556,aR2＝0.0009,bR2＝0.350,aL1＝0.220,bL1＝-0.864,cL1＝0.00475,aL2＝0.072,bL2＝-0.586,and cL2＝0.000553.D1＝40，D2＝30.
After fitting, the winding resistance and inductance of each side at any frequency can be read, the winding resistance and inductance of each layer are obtained by equally dividing the winding resistance and inductance of the side.
(3) According to the structure and physical size of a transformer winding to be measured, a 2D electrostatic field single-phase model (a cylindrical coordinate system) is constructed in Ansys/Maxwell simulation software, as shown in FIG. 5, wherein (a) is a model for calculating interlayer capacitance; (b) to calculate the turn-to-turn capacitance model. All capacitance parameters representing insulation in the model are calculated, including ground capacitance, interlayer capacitance and turn-to-turn capacitance representing main insulation of each layer to the ground, as shown in table 2.
TABLE 2 exemplary Transformer insulation capacitance parameters
(4) Given the dielectric loss factor df (f) at each scanning frequency, as an empirical value, all parameters characterizing the resistance in the insulated parallel branches are calculated by the following formula:
R(f)＝1/[2πf·C·DF(f)]. (2)
the broadband results are shown in fig. 6, with the symbols corresponding to the capacitance parameters in table 2.
(5) According to the structure and physical size of a transformer winding to be measured, a 3D static magnetic field three-phase model (Cartesian coordinate system) is constructed in Ansys/Maxwell simulation software, and all mutual inductance parameters representing inductive coupling in the model are calculated. Because the primary winding has 3 layers and the secondary winding has 2 layers, inductance matrixes calculated by Ansys/Maxwell simulation software are 15 × 15 square matrixes under each simulation frequency f. Taking f as an example of 1kHz, the square matrix results are as follows:
and selecting the upper triangular elements of each simulation under each frequency in the model to represent different mutual inductance parameters. For example, the mutual inductance between the first layer and the second layer on the primary side is the value of the second column in the first row, 0.000566H; the secondary side is used as a fourth layer and a fifth layer, and the mutual inductance between the secondary side second layer and the primary side third layer is the value of a fifth row and a fifth column of the second row, 0.000536H.
So far, the broadband parameterization results of all the elements in fig. 4 are obtained, and the parameter acquisition takes into account the non-uniform distribution characteristic and the frequency variation characteristic.
In Simulink simulation software, responses are obtained for the excitation under different frequencies, and response curves are obtained. The response curves were compared.
Fig. 7 shows the results of comparing 4 sets of frequency response curves for an exemplary power transformer, including an off-line experimental test curve based on an impedance analyzer, a simulation curve based on the model of the present invention, and two sets of simulation curves based on a conventional N-ladder model. The non-uniform distribution characteristic of model parameters is not considered in the two traditional models, the interlayer insulation between windings on the same side is considered in the traditional model 1, and the interlayer insulation between windings on the same side is not considered in the traditional model 2. The off-line experimental test curve based on the impedance analyzer can be regarded as an accurate broadband curve (baseline). Comparing 3 groups of model simulation results, the simulation curve based on the model of the invention is basically consistent with the reference curve; and the other two groups of simulation curves based on the traditional model are not matched with the reference curve in the distribution of the resonance points of the curve amplitude in the high frequency band. Furthermore, the model has the advantages that the change rule of the broadband curve can be accurately explored, and the condition monitoring and evaluation of the power transformer based on the FRA method can be better served.
In summary, the invention relates to a frequency response test method based on a transformer broadband model and application thereof, the number of layers of windings on two sides is determined according to a winding structure of a transformer to be tested, a common-mode broadband circuit model of the transformer to be tested is formed, each layer comprises a series structure formed by a winding inductance and a winding resistance, two ends of the series structure are grounded through a grounding capacitor and are connected in parallel with an inter-turn capacitor, the layers are connected through an interlayer capacitor, each capacitor is connected in parallel with a resistor, and winding mutual inductance exists between different layers; determining characteristic parameters of each component in the model; and calculating a frequency response curve based on the transformer broadband model. The model can more accurately represent the frequency variation characteristic in the wide frequency band of the electrical parameters, improve the accuracy of describing the change of the resonance point of the high frequency band caused by insulation aging or winding deformation, and more accurately explore the change rule of the wide frequency response test curve. The method can better serve for monitoring and evaluating the state of the power transformer based on the FRA method, can serve for detecting the aging state, and accurately evaluates the state difference before and after aging.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (10)
1. A frequency response test method based on a transformer broadband model is characterized by comprising the following steps:
determining the number of layers of windings on two sides according to a winding structure of a transformer to be tested to form a common-mode broadband circuit model of the transformer to be tested, wherein each layer comprises a series structure formed by a winding inductor and a winding resistor, two ends of the series structure are grounded through a grounding capacitor and connected in parallel with an inter-turn capacitor, the layers are connected through an interlayer capacitor, each capacitor is connected in parallel with a resistor, and winding mutual inductance exists between different layers;
determining characteristic parameters of components of a common-mode wide-frequency circuit model of the transformer to be tested at each scanning frequency;
and calculating a frequency response curve based on the transformer broadband model.
2. The method for testing frequency response based on the transformer broadband model according to claim 1, wherein determining the characteristic parameters of each component of the transformer common-mode broadband circuit model to be tested at each scanning frequency comprises:
measuring the winding inductance and the winding resistance of each side under the scanning frequency according to the winding conductor parameters of the two sides of the transformer to be measured, fitting to obtain the winding resistance and the winding inductance of each side under the continuous frequency spectrum, and calculating the winding resistance and the winding inductance of each layer;
according to structural parameters of windings on two sides of a transformer to be tested, a 2D electrostatic field single-phase model is constructed in simulation software, and ground capacitance, turn-to-turn capacitance and interlayer capacitance of each layer are obtained;
calculating the parallel resistance of each capacitor according to the dielectric loss factor under each scanning frequency;
according to the structural parameters of the windings on the two sides of the transformer to be measured, a 3D static magnetic field three-phase model is constructed in simulation software, common mode excitation is added, and the winding mutual inductance between layers under the scanning frequency is calculated.
3. The method for testing frequency response based on the wideband model of the transformer according to claim 2, wherein the fitting formula for obtaining the winding resistance and the winding inductance of each side under the continuous spectrum by fitting is as follows:
FRi(f) denotes the winding resistance, FLi(f) Denotes a winding inductance, i denotes a primary winding when i is 1, denotes a secondary winding when i is 2, and aRi,bRi,aLi,bLi,cLiIs a fitting parameter, DiIs the length of the windings on both sides.
4. The method for testing frequency response based on the wideband transformer model according to claim 2, wherein the parallel resistance r (f) of each capacitor is calculated according to the dielectric loss factor df (f) at each scanning frequency, and the formula is:
R(f)＝1/[2πf·C(f)·DF(f)]
where C (f) is the capacitance and f is the scanning frequency.
5. The method for testing frequency response based on the transformer broadband model according to one of claims 2 to 4, wherein the step of calculating the frequency response curve based on the transformer broadband model comprises:
in Simulink software, a transformer common-mode broadband circuit model is constructed, excitation under different scanning frequencies is given to solve the response, and a response curve is obtained.
6. A transformer condition monitoring method, comprising:
determining the number of layers of windings on two sides according to a winding structure of a transformer to be tested to form a common-mode broadband circuit model of the transformer to be tested, wherein each layer comprises a series structure formed by a winding inductor and a winding resistor, two ends of the series structure are grounded through a grounding capacitor and connected in parallel with an inter-turn capacitor, the layers are connected through an interlayer capacitor, each capacitor is connected in parallel with a resistor, and winding mutual inductance exists between different layers; determining characteristic parameters of components of a common-mode wide-frequency circuit model of the transformer to be tested at each scanning frequency;
simulating various defects of the transformer in simulation software, changing characteristic parameters of various elements of the common-mode broadband circuit model, obtaining a frequency response curve under various defects, obtaining the amplitude of the frequency response curve under various defects and the variation rule of the deviation of the resonance point, and storing the amplitude and the deviation;
before the transformer to be tested is put into operation, detecting the frequency response under each scanning frequency to form a frequency response curve under the actual health condition;
after the transformer is put into operation, the frequency response curves of the transformer to be tested in actual operation at different time intervals are obtained and compared with the stored frequency response curves under actual health conditions, and the health state of the transformer is determined through curve movement and resonance point change.
7. The transformer condition monitoring method of claim 6, further comprising: under each scanning frequency point, comparing the frequency response curve in actual work at the current time period with the stored frequency response curve under the health condition of the testing transformer, calculating the deviation of the amplitude and the resonance point, comparing the deviation with the stored change rule when the deviation exceeds a deviation threshold value, and taking the defect type corresponding to the change rule with the amplitude and the resonance point deviation closest to each other as the defect of the to-be-tested transformer; and when the deviation does not exceed the deviation threshold, the state of the transformer to be tested is normal.
8. A transformer aging state detection method is characterized by comprising the following steps:
obtaining and storing a frequency response curve of a transformer to be tested in a normal state by using the frequency response testing method based on the transformer broadband model according to any one of claims 1 to 5;
detecting frequency response under each scanning frequency to form a frequency response curve under the actual health condition;
aging the transformer to be tested;
and testing the frequency response curve of the transformer to be tested in actual work, comparing the frequency response curve with the stored frequency response curve under the actual health condition, and determining the state after aging through curve movement and resonance point change.
9. The method of detecting a degradation state of a transformer according to claim 8, further comprising: simulating various defects of the transformer in simulation software, changing characteristic parameters of various elements of the common-mode broadband circuit model, obtaining a frequency response curve under various defects, and obtaining the amplitude of the frequency response curve under various defects and the variation rule of the deviation of a resonance point;
under each scanning frequency point, comparing a frequency response curve in actual work with a stored frequency response curve under an actual health condition, calculating the deviation of the amplitude and the resonance point, comparing the deviation with the change rule when the deviation exceeds a deviation threshold value, and taking the defect type corresponding to the change rule with the amplitude and the resonance point deviation closest as the defect of the transformer to be detected; and when the deviation does not exceed the deviation threshold, the state of the transformer to be tested is normal.
10. The power equipment monitoring system is characterized by comprising a first storage module, a detection module and a comparison module;
determining the number of layers of windings on two sides according to a winding structure of a transformer to be tested to form a common-mode broadband circuit model of the transformer to be tested, wherein each layer comprises a series structure formed by a winding inductor and a winding resistor, two ends of the series structure are grounded through a grounding capacitor and connected in parallel with an inter-turn capacitor, the layers are connected through an interlayer capacitor, each capacitor is connected in parallel with a resistor, and winding mutual inductance exists between different layers; determining characteristic parameters of components of a common-mode wide-frequency circuit model of the transformer to be tested at each scanning frequency; storing the common-mode broadband circuit model; in simulation software, changing each characteristic parameter of the common-mode broadband circuit model, simulating various defects of the transformer, and obtaining a frequency response curve under the various defects; obtaining the change rule of the amplitude of the frequency response curve and the deviation of the resonance point under various defects, and storing the change rule by the first storage module;
the detection module detects frequency response under each scanning frequency before the transformer to be detected is put into operation to form a frequency response curve under actual health conditions; detecting frequency response under each scanning frequency in the operation period of the transformer to be detected, forming a frequency response curve in actual operation, and storing the frequency response curves in the actual operation at different time periods;
the comparison module is used for comparing the frequency response curves stored by the detection module in different periods of actual work with the frequency response curves stored by the detection module under actual health conditions, calculating the deviation of the amplitude and the resonance point, comparing the deviation with the change rule stored by the first storage module when the deviation exceeds a deviation threshold value, and taking the defect type corresponding to the change rule with the amplitude and the resonance point closest to the deviation as the defect of the transformer to be detected; and when the deviation does not exceed the deviation threshold, the state of the transformer to be tested is normal.
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Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030139891A1 (en) * | 2002-01-18 | 2003-07-24 | Coffeen Larry T. | Systems and methods for multiple winding impulse frequency response analysis test |
| US20050099187A1 (en) * | 2003-10-03 | 2005-05-12 | Areva T&D Sa | Method of diagnosing a fault on a transformer winding |
| CN106597150A (en) * | 2016-11-29 | 2017-04-26 | 武汉振源电气股份有限公司 | Voltage transformer on-line state monitoring and fault diagnosing method |
| CN106841905A (en) * | 2017-04-14 | 2017-06-13 | 云南电网有限责任公司电力科学研究院 | A kind of recognition methods of transformer short circuit fault and device |
| CN107656174A (en) * | 2017-08-07 | 2018-02-02 | 中国电力科学研究院 | One kind is used for deformation of transformer winding and carries out inline diagnosis method and system |
| CN108932368A (en) * | 2018-06-04 | 2018-12-04 | 浙江省送变电工程有限公司 | A kind of emulation mode of the deformation of transformer winding frequency response based on MATLAB |
| CN110398643A (en) * | 2018-11-05 | 2019-11-01 | 国网新疆电力有限公司电力科学研究院 | A kind of detection of electric system deformation of transformer winding and diagnostic method |
| CN110514924A (en) * | 2019-08-12 | 2019-11-29 | 武汉大学 | The Winding in Power Transformer Fault Locating Method of depth convolutional neural networks fusion visual recognition |
| CN110850340A (en) * | 2019-11-19 | 2020-02-28 | 西南大学 | Transformer winding IFRA curve denoising method based on wavelet transformation |
| CN111273199A (en) * | 2018-12-05 | 2020-06-12 | 国网四川省电力公司眉山供电公司 | Intelligent detection method for transformer winding deformation based on sweep frequency impedance curve identification |
| US20200241081A1 (en) * | 2019-08-09 | 2020-07-30 | Tsinghua University | Ground-wall insulation aging monitoring and locating method for converter transformer |
| CN111736100A (en) * | 2020-06-11 | 2020-10-02 | 广东电网有限责任公司 | Method and system for dynamically dividing frequency response curve of transformer into frequency bands, storage medium and computer equipment |
-
2020
- 2020-12-01 CN CN202011385705.1A patent/CN112595998B/en active Active
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030139891A1 (en) * | 2002-01-18 | 2003-07-24 | Coffeen Larry T. | Systems and methods for multiple winding impulse frequency response analysis test |
| US20050099187A1 (en) * | 2003-10-03 | 2005-05-12 | Areva T&D Sa | Method of diagnosing a fault on a transformer winding |
| CN106597150A (en) * | 2016-11-29 | 2017-04-26 | 武汉振源电气股份有限公司 | Voltage transformer on-line state monitoring and fault diagnosing method |
| CN106841905A (en) * | 2017-04-14 | 2017-06-13 | 云南电网有限责任公司电力科学研究院 | A kind of recognition methods of transformer short circuit fault and device |
| CN107656174A (en) * | 2017-08-07 | 2018-02-02 | 中国电力科学研究院 | One kind is used for deformation of transformer winding and carries out inline diagnosis method and system |
| CN108932368A (en) * | 2018-06-04 | 2018-12-04 | 浙江省送变电工程有限公司 | A kind of emulation mode of the deformation of transformer winding frequency response based on MATLAB |
| CN110398643A (en) * | 2018-11-05 | 2019-11-01 | 国网新疆电力有限公司电力科学研究院 | A kind of detection of electric system deformation of transformer winding and diagnostic method |
| CN111273199A (en) * | 2018-12-05 | 2020-06-12 | 国网四川省电力公司眉山供电公司 | Intelligent detection method for transformer winding deformation based on sweep frequency impedance curve identification |
| US20200241081A1 (en) * | 2019-08-09 | 2020-07-30 | Tsinghua University | Ground-wall insulation aging monitoring and locating method for converter transformer |
| CN110514924A (en) * | 2019-08-12 | 2019-11-29 | 武汉大学 | The Winding in Power Transformer Fault Locating Method of depth convolutional neural networks fusion visual recognition |
| CN110850340A (en) * | 2019-11-19 | 2020-02-28 | 西南大学 | Transformer winding IFRA curve denoising method based on wavelet transformation |
| CN111736100A (en) * | 2020-06-11 | 2020-10-02 | 广东电网有限责任公司 | Method and system for dynamically dividing frequency response curve of transformer into frequency bands, storage medium and computer equipment |
Non-Patent Citations (6)
| Title |
|---|
| DIGVIJAY DESWAL 等: "Generalized Circuit Model for Eddy Current Effects in Multi-Winding Transformers", 《IEEE TRANSACTIONS ON POWER DELIVERY》 * |
| GEYE LU 等: "An Advanced Wide-band Model and A Novel Multi-type Insulation Monitoring Strategy for VSC-connected Transformers Based on Common-mode Impedance Respons", 《IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS》 * |
| ORESTES HERNÁNDEZ ARÉU 等: "Diagnosis of faults in power transformers through the interpretation of FRA testing with artificial intelligence", 《2018 IEEE INTERNATIONAL AUTUMN MEETING ON POWER, ELECTRONICS AND COMPUTING (ROPEC)》 * |
| 张延寿 等: "变压器绕组变形的纳秒脉冲频率响应仿真研究", 《电力系统及其自动化》 * |
| 王忠东 等: "局部放电脉冲在单绕组变压器中", 《电网技术》 * |
| 蔡建昌: "基于频率响应法的变压器绕组变形试验分析", 《电力建设》 * |
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