Power distribution transformer winding health state evaluation method, system, device and medium

Abstract

The present application relates to a kind of distribution transformer winding health state evaluation method, system, equipment and medium, the method includes obtaining transformer operating data and corresponding nameplate parameter;Determine the ratio based on nameplate parameter, by the ratio to transformer operating data is converted, obtain primary side phase voltage and secondary side output phase current, fold to same side after secondary side phase voltage and primary side phase voltage calculation voltage difference, according to voltage difference and secondary side output phase current generation relationship trajectory;Based on nameplate parameter and transformer operating data, Γ type equivalent circuit is constructed to estimate excitation impedance and load impedance, according to excitation impedance and load impedance, load equivalent conversion is carried out to voltage difference, and load equivalent voltage difference is obtained;Based on load equivalent voltage difference and secondary side output phase current, the inclination angle and axis length ratio of relationship trajectory are determined, and the winding health state evaluation result of distribution transformer is output according to the inclination angle and axis length ratio.The present application has the effect of improving the reliability of evaluation.

Description

Technical Field

[0001] This invention belongs to the technical field of monitoring the operating status of distribution transformers, and in particular relates to a method, system, equipment and medium for assessing the health status of distribution transformer windings. Background Technology

[0002] Currently, there are a large number of distribution transformers in the power distribution network, which are widely distributed and operate in an environment of frequent load fluctuations and changing operating conditions. The insulation and structural condition of the windings, as key components, will change over time. The data that can be obtained on-site mainly comes from the voltage, current and nameplate parameters on the operating side. The data acquisition conditions are constrained by factors such as the equipment power outage window, measurement side and sampling consistency.

[0003] Existing winding health status assessments are usually based on the characteristic relationships of operating quantities to make judgments or to obtain characterization quantities through equivalent analysis and output assessment conclusions accordingly. However, when the load level changes significantly or the operating conditions are unstable, the assessment process is easily affected by the load and may cause deviations, making the relationship characteristics unstable and resulting in insufficient consistency and reliability of the assessment results. Summary of the Invention

[0004] The purpose of this invention is to provide a method, system, device, and medium for assessing the health status of distribution transformer windings, in order to solve the technical problem that existing winding health status assessment methods suffer from increased deviations in assessment results due to the influence of load changes on the stability of the relationship characteristics.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for assessing the health status of distribution transformer windings, the method comprising: Acquire transformer operating data and corresponding nameplate parameters, wherein the transformer operating data includes primary phase current and secondary phase voltage; The turns ratio is determined based on the nameplate parameters. The transformer operating data is then converted using the turns ratio to obtain the primary phase voltage and the secondary output phase current. The secondary phase voltage is converted to the same side and the voltage difference is calculated with the primary phase voltage. A relationship trajectory is generated based on the voltage difference and the secondary output phase current. Based on the nameplate parameters and the transformer operating data, a Γ-type equivalent circuit is constructed to estimate the excitation impedance and load impedance. The voltage difference is then converted to a load equivalent voltage difference based on the excitation impedance and load impedance. The tilt angle and shaft length ratio of the relationship trajectory are determined based on the load equivalent voltage difference and the secondary output phase current, and the winding health status assessment result of the distribution transformer is output according to the tilt angle and the shaft length ratio.

[0006] By adopting the above technical solutions, and by acquiring transformer operating data and corresponding nameplate parameters, the operating quantities and rated quantities can be established on the same reference basis, thus providing consistent data input for subsequent conversion and parameter estimation. By determining the turns ratio based on the nameplate parameters and converting the transformer operating data to obtain the primary phase voltage and secondary output phase current, and calculating the voltage difference and generating a relationship trajectory, the primary and secondary quantities can be unified to the same dimension and form a trajectory representation reflecting the coupling characteristics of voltage difference and output current, thereby improving the sensitivity and identifiability to changes in winding status. By constructing a Γ-type equivalent circuit to estimate the excitation impedance and load impedance and performing load equivalent conversion on the voltage difference to obtain the load equivalent voltage difference, the influence of load fluctuations on the voltage difference representation can be weakened and a more stable equivalent input quantity can be obtained, thereby improving the consistency and comparability of the evaluation process under different operating conditions. By determining the tilt angle and shaft length ratio of the relationship trajectory based on the load equivalent voltage difference and secondary output phase current and outputting the evaluation results, the trajectory shape can be transformed into quantifiable characteristic indicators, and the health status can be judged accordingly, thereby improving the intuitiveness and feasibility of winding health status evaluation.

[0007] In one example, the present invention can be further configured as follows: determining the turns ratio based on the nameplate parameters, calculating the transformer operating data using the turns ratio to obtain the primary side phase voltage and the secondary side output phase current, calculating the voltage difference between the secondary side phase voltage (after converting it to the same side) and the primary side phase voltage, and generating a relationship trajectory based on the voltage difference and the secondary side output phase current, including: The turns ratio is determined based on the rated voltage parameter in the nameplate parameters. The primary phase current is calculated based on the transformer ratio to obtain the secondary output phase current; The secondary phase voltage is calculated based on the turns ratio to obtain the calculated secondary phase voltage, and the primary phase voltage is determined based on the calculated secondary phase voltage. The voltage difference is calculated based on the primary phase voltage and the converted secondary phase voltage, and the relationship trajectory is generated based on the voltage difference and the secondary output phase current.

[0008] By adopting the above technical solutions, the turns ratio is determined based on the rated voltage parameter in the nameplate parameters, ensuring that the turns ratio value is consistent with the rated quantity of the transformer, thereby reducing the impact of turns ratio selection deviation on the subsequent conversion accuracy. By converting the primary side phase current based on the turns ratio to obtain the secondary side output phase current, the same-side output current characterization can be obtained without changing the acquisition side layout, thus supporting the consistency of current input in the generation of the relationship trajectory. By converting the secondary side phase voltage based on the turns ratio and determining the primary side phase voltage accordingly, the same-side expression of voltage quantities can be achieved and the comparison error caused by side differences can be reduced, thereby improving the reliability of voltage difference calculation. By calculating the voltage difference based on the primary side phase voltage and the converted secondary side phase voltage and combining it with the secondary side output phase current to generate the relationship trajectory, a mapping trajectory consistent with the sampling time sequence can be formed, thereby improving the stability and repeatability of trajectory construction.

[0009] In one example, the present invention can be further configured as follows: calculating the voltage difference based on the primary phase voltage and the reduced secondary phase voltage, and generating the relationship trajectory based on the voltage difference and the secondary output phase current, includes: The primary phase voltage and the converted secondary phase voltage are sampled synchronously to obtain the voltage alignment sequence of the corresponding sampling points; Perform difference calculation on the voltage alignment sequence to generate the voltage difference; The relationship trajectory is obtained by mapping the voltage difference and the secondary output phase current in a rectangular coordinate system.

[0010] By adopting the above technical solution, a voltage alignment sequence is obtained by synchronously sampling the primary phase voltage and the converted secondary phase voltage. This ensures that the two voltages are aligned under the same sampling time scale, thereby avoiding voltage difference distortion caused by time offset. By performing difference calculation on the voltage alignment sequence to generate the voltage difference, a difference feature quantity consistent with the operating sequence can be obtained, thereby improving the accuracy of the voltage difference in representing changes in winding state. By mapping the voltage difference and the secondary output phase current in a rectangular coordinate system to obtain the relationship trajectory, the time series data can be transformed into a geometric trajectory shape, thus providing a calculable trajectory basis for subsequent elliptical trajectory fitting and feature extraction.

[0011] In one example, the present invention can be further configured as follows: the step of constructing a Γ-type equivalent circuit based on the nameplate parameters and the transformer operating data to estimate the excitation impedance and load impedance, and performing a load equivalent conversion on the voltage difference based on the excitation impedance and the load impedance to obtain the load equivalent voltage difference, includes: The rated voltage, rated current, impedance voltage, and load loss are extracted from the nameplate parameters to generate an equivalent parameter set; The Γ-type equivalent circuit is constructed based on the equivalent parameter set, and the transformer operating data and the Γ-type equivalent circuit are correlated to obtain the impedance estimation input; Based on the impedance estimation input, the excitation impedance and the load impedance are solved to obtain the impedance estimation result; Based on the impedance estimation results, the load equivalent conversion relationship is determined, and the voltage difference is converted according to the load equivalent conversion relationship to obtain the load equivalent voltage difference.

[0012] By adopting the above technical solutions, and extracting rated voltage, rated current, impedance voltage, and load loss from nameplate parameters to generate an equivalent parameter set, the key rated information required for equivalent circuit modeling can be structurally collected, thereby reducing estimation errors caused by missing parameters or inconsistent specifications. By constructing a Γ-type equivalent circuit based on the equivalent parameter set and correlating the operating data with the Γ-type equivalent circuit to obtain impedance estimation input, a correspondence between operating quantities and equivalent circuit variables can be established, thereby improving the constraint and feasibility of impedance solution. By solving for excitation impedance and load impedance based on impedance estimation input to obtain impedance estimation results, an equivalent impedance characterization matching the current operating state can be obtained, thus providing a reliable parameter basis for load equivalent conversion. By determining the load equivalent conversion relationship based on the impedance estimation results and performing load equivalent conversion on the voltage difference to obtain the load equivalent voltage difference, the voltage difference response under different load conditions can be converted to a comparable reference scale, thereby improving the stability and comparability of subsequent trajectory characteristic indicators.

[0013] In one example, the present invention can be further configured as follows: the step of solving for the excitation impedance and the load impedance based on the impedance estimation input to obtain the impedance estimation result includes: The voltage and current quantities corresponding to the Γ-type equivalent circuit are extracted from the impedance estimation input to generate the impedance solution input. By associating the impedance solution input with the equivalent parameter set, impedance solution constraints are obtained. The excitation impedance and the load impedance are obtained by solving the impedance constraints, and the impedance estimation result is generated.

[0014] By adopting the above technical solution, the voltage and current quantities corresponding to the Γ-type equivalent circuit are extracted from the impedance estimation input to generate the impedance solution input. This clarifies the measurement of the quantities required for the solution and establishes a one-to-one correspondence with the circuit variables, thereby improving the data completeness of the impedance solution process. By associating the impedance solution input and the equivalent parameter set to obtain the impedance solution constraints, the rated parameter constraints can be introduced into the solution process to limit the solution space, thereby reducing the risk of parameter drift caused by ill-posed solutions. By solving for the excitation impedance and load impedance based on the impedance solution constraints and generating the impedance estimation results, the equivalent impedance parameters that meet the constraints can be output, thereby improving the reliability and consistency of the subsequent determination of the load equivalent conversion relationship.

[0015] In one example, the present invention can be further configured as follows: determining the tilt angle and shaft length ratio of the relationship trajectory based on the load equivalent voltage difference and the secondary output phase current, and outputting the winding health status assessment result of the distribution transformer according to the tilt angle and the shaft length ratio, includes: The elliptical trajectory corresponding to the relationship trajectory is determined based on the load equivalent voltage difference and the secondary side output phase current. The tilt angle is determined based on the elliptical trajectory, and the major and minor axes of the elliptical trajectory are also determined. The axis length ratio is calculated based on the major axis and the minor axis, and the winding health status assessment result is output according to the tilt angle and the axis length ratio.

[0016] By adopting the above technical solution, and determining the elliptical trajectory corresponding to the relationship trajectory based on the equivalent load voltage difference and the secondary output phase current, the voltage difference-current coupling relationship can be stably fitted at the geometric level, thereby reducing the impact of discrete sampling fluctuations on trajectory shape recognition. By determining the tilt angle and major and minor axes based on the elliptical trajectory, key geometric parameters reflecting the trajectory direction and scale characteristics can be extracted, thereby enhancing the distinguishability of changes in winding health status. By calculating the axis length ratio based on the major and minor axes and combining it with the tilt angle to output the evaluation results, the geometric parameters can be transformed into quantitative indicators that can be used for discrimination, thereby realizing the intuitive output and engineering application of winding health status evaluation results.

[0017] In one example, the present invention can be further configured as follows: determining the elliptical trajectory corresponding to the relationship trajectory based on the load equivalent voltage difference and the secondary-side output phase current includes: Fast Fourier decomposition is performed on the equivalent voltage difference of the load and the output phase current of the secondary side to obtain the corresponding fundamental amplitude information and fundamental phase information; The phase difference between the load equivalent voltage difference and the secondary side output phase current is determined based on the fundamental phase information. The trajectory parameters of the elliptical trajectory are determined based on the fundamental amplitude information and the phase difference to obtain the elliptical trajectory.

[0018] By adopting the above technical solution, the fundamental amplitude and phase information are obtained by performing Fast Fourier Decomposition on the equivalent load voltage difference and the secondary output phase current. This allows for the extraction of the dominant component from the operating signal and the suppression of harmonic and noise interference, thereby improving the robustness of the elliptical trajectory parameter calculation. By determining the phase difference between the equivalent load voltage difference and the secondary output phase current based on the fundamental phase information, a phase characteristic quantity reflecting the coupling relationship between the two can be obtained, thus improving the interpretability of the elliptical trajectory morphology parameters. By determining the trajectory parameters of the elliptical trajectory based on the fundamental amplitude information and the phase difference, the key trajectory parameters can be reconstructed with stable frequency domain characteristics, thereby improving the consistency and repeatability of subsequent tilt angle and axis length ratio calculations.

[0019] In a second aspect, the present invention provides a system for assessing the health status of distribution transformer windings, the system comprising: The data acquisition module is used to acquire transformer operating data and corresponding nameplate parameters. The transformer operating data includes primary phase current and secondary phase voltage. The turns ratio conversion module is used to determine the turns ratio based on the nameplate parameters, convert the transformer operating data through the turns ratio to obtain the primary side phase voltage and the secondary side output phase current, convert the secondary side phase voltage to the same side and calculate the voltage difference with the primary side phase voltage, and generate a relationship trajectory based on the voltage difference and the secondary side output phase current. The impedance estimation module is used to construct a Γ-type equivalent circuit based on nameplate parameters and transformer operating data to estimate excitation impedance and load impedance. Based on the excitation impedance and load impedance, the voltage difference is converted to load equivalent to obtain the load equivalent voltage difference. The index evaluation module is used to determine the tilt angle and shaft length ratio of the relationship trajectory based on the load equivalent voltage difference and the secondary output phase current, and output the winding health status evaluation results of the distribution transformer according to the tilt angle and shaft length ratio.

[0020] By adopting the above technical solutions, and by acquiring transformer operating data and corresponding nameplate parameters, the operating quantities and rated quantities can be established on the same reference basis, thus providing consistent data input for subsequent conversion and parameter estimation. By determining the turns ratio based on the nameplate parameters and converting the transformer operating data to obtain the primary phase voltage and secondary output phase current, and calculating the voltage difference and generating a relationship trajectory, the primary and secondary quantities can be unified to the same dimension and form a trajectory representation reflecting the coupling characteristics of voltage difference and output current, thereby improving the sensitivity and identifiability to changes in winding status. By constructing a Γ-type equivalent circuit to estimate the excitation impedance and load impedance and performing load equivalent conversion on the voltage difference to obtain the load equivalent voltage difference, the influence of load fluctuations on the voltage difference representation can be weakened and a more stable equivalent input quantity can be obtained, thereby improving the consistency and comparability of the evaluation process under different operating conditions. By determining the tilt angle and shaft length ratio of the relationship trajectory based on the load equivalent voltage difference and secondary output phase current and outputting the evaluation results, the trajectory shape can be transformed into quantifiable characteristic indicators, and the health status can be judged accordingly, thereby improving the intuitiveness and feasibility of winding health status evaluation.

[0021] In a third aspect, the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method for assessing the health status of a distribution transformer winding.

[0022] In a fourth aspect, the present invention provides a storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method for assessing the health status of a distribution transformer winding. Attached Figure Description

[0023] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of a method for assessing the health status of distribution transformer windings in an embodiment of the present invention; Figure 2 This is a T-type equivalent circuit diagram of a single-phase distribution transformer in an embodiment of the present invention; Figure 3 This is the Γ-type equivalent circuit diagram of a single-phase distribution transformer in an embodiment of the present invention; Figure 4 This is the vector diagram corresponding to the transformer T-type equivalent circuit diagram in the embodiments of the present invention; Figure 5 This is a schematic diagram of the characteristic variables in the elliptical trajectory curve in an embodiment of the present invention; Figure 6This is a structural block diagram of the distribution transformer winding health status assessment system according to an embodiment of the present invention; Figure 7 This is a structural block diagram of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0025] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0026] Example 1 like Figure 1 As shown, this invention discloses a method for assessing the health status of distribution transformer windings, specifically including the following steps: S10: Obtain transformer operating data and corresponding nameplate parameters. The transformer operating data includes primary phase current and secondary phase voltage.

[0027] Specifically, voltage transformers are used to collect phase voltage data u2(t) of the secondary winding at corresponding phases on the secondary side of the distribution transformer, and current transformers are used to collect phase current data i1(t) of the primary winding at corresponding phases on the primary side of the distribution transformer. u2(t) and i1(t) are synchronously recorded under the same sampling time scale to form an operational data sequence. Simultaneously, the rated capacity SN, rated voltage U of the primary and secondary windings are read from the nameplate parameters. 1N with U 2N No-load loss P0, load loss P k No-load current I0 (%), impedance voltage U k (%) and rated current I 1N with I 2N And form a set of nameplate parameters; Furthermore, the constraint that the primary winding is directly connected to the power grid allows the primary phase voltage to be considered a sinusoidal quantity with constant amplitude and its initial phase to be assumed to be 0. This allows the primary and secondary phase voltages to be correlated with the phase current. It is represented as, where ω is the frequency, and U 1N U1 is the rated voltage of the primary side, U2, I1, and I2 are the amplitudes of the phase voltage or phase current, and θ, δ, and φ are the corresponding initial phases.

[0028] S20: Determine the turns ratio based on the nameplate parameters, calculate the transformer operating data using the turns ratio, obtain the primary side phase voltage and the secondary side output phase current, calculate the voltage difference between the secondary side phase voltage and the primary side phase voltage after converting the secondary side phase voltage to the same side, and generate a relationship trajectory based on the voltage difference and the secondary side output phase current.

[0029] Specifically, based on the nameplate parameters, the corresponding relationship between the rated voltages of the primary and secondary sides is obtained and the turns ratio k is determined. The phase current of the primary side and the phase voltage of the secondary side are converted on the same side according to the turns ratio to obtain the phase voltage and output phase current for comparison on the same side. Under the same sampling time scale, the converted phase voltage and the converted secondary phase voltage form a voltage difference sequence and are time-corresponded with the output phase current sequence of the secondary side. The voltage difference and output phase current corresponding to each sampling point are used as a set of mapping points and connected in time sequence to form a relationship trajectory.

[0030] S30: Construct a Γ-type equivalent circuit based on nameplate parameters and transformer operating data to estimate excitation impedance and load impedance. Perform load equivalent conversion on the voltage difference based on the excitation impedance and load impedance to obtain the load equivalent voltage difference.

[0031] Specifically, based on nameplate parameters and transformer operating data, a single-phase equivalent relationship of the distribution transformer is established and a system is constructed. Figure 2 , Figure 3 and Figure 4 Consistent equivalent circuit representation, such as Figure 2 The T-type equivalent circuit diagram of a single-phase distribution transformer shown is used to describe the electrical relationship between the primary side series impedance and the excitation branch, and the converted secondary side series impedance and the load branch, such as... Figure 4 The transformer T-type equivalent circuit diagram shown is used to characterize the phasor relationship between phase voltage, phase current, and impedance voltage drop. Further methods are then employed based on this. Figure 3 The Γ-type equivalent circuit diagram of a single phase of the distribution transformer shown in the figure combines the equivalent circuit parameters and establishes a correlation with the transformer operating data to form an impedance estimation input. By solving for the excitation impedance and load impedance, the equivalent load conversion relationship is constructed, thereby converting the voltage difference into the equivalent load voltage difference that eliminates the influence of load fluctuations.

[0032] S40: Determine the tilt angle and shaft length ratio of the relationship trajectory based on the load equivalent voltage difference and the secondary output phase current, and output the winding health status assessment result of the distribution transformer according to the tilt angle and shaft length ratio.

[0033] Specifically, based on the relationship trajectory between the load equivalent voltage difference and the secondary side output phase current, characteristic variables are extracted, and the tilt angle θ and the axis length ratio τ are obtained as dual monitoring indicators, such as... Figure 5The schematic diagram of the characteristic variables in the elliptical trajectory curve is used to illustrate the geometric correspondence between the tilt angle, the major axis, the minor axis, and the axis length ratio. The tilt angle θ and the axis length ratio τ are compared with the standard values ​​under rated operating conditions, and the winding health status assessment results are output in combination with the threshold criterion. The assessment results are used to indicate the health status of the winding inter-turn insulation and can be interpreted and verified in subsequent embodiments in combination with the changes in monitoring indicators under different fault severity and different load conditions.

[0034] In one embodiment, in step S20, the turns ratio is determined based on the nameplate parameters. The transformer operating data is then converted using the turns ratio to obtain the primary side phase voltage and the secondary side output phase current. After converting the secondary side phase voltage to the same side, the voltage difference is calculated with the primary side phase voltage. A relationship trajectory is generated based on the voltage difference and the secondary side output phase current, including: S21: Determine the turns ratio based on the rated voltage parameters in the nameplate parameters.

[0035] Specifically, the primary side rated voltage U is read from the nameplate parameters. 1N With the secondary side rated voltage U 2N And establish the correspondence between the primary and secondary rated voltages, based on the primary rated voltage U 1N With the secondary side rated voltage U 2N Calculate the ratio k=U 1N / U 2N The turns ratio k is obtained and used as a scaling factor for subsequent conversion of the primary phase current and the secondary phase voltage on the same side.

[0036] S22: The primary phase current is calculated based on the transformer ratio to obtain the secondary output phase current.

[0037] Specifically, based on the turns ratio k, current conversion is performed on the primary side phase current i1(t) to obtain the secondary side output phase current i2(t). The conversion satisfies the voltage-current turns ratio relationship and ensures that the converted secondary side output phase current is consistent with the secondary side quantity. This is combined with the rated current I in the nameplate parameters. 1N and I2N The current quantity is normalized to form a normalized output current, and the primary phase current is normalized to a normalized value. The secondary side output phase current is per-unit scalarized. Where I1 and I2 are the current amplitudes of i1(t) and i2(t), respectively. and These are the per-unit coefficients of the amplitude relative to the rated current.

[0038] S23: Based on the turns ratio, the secondary phase voltage is calculated to obtain the calculated secondary phase voltage, and the primary phase voltage is determined based on the calculated secondary phase voltage.

[0039] Specifically, based on the turns ratio k, the secondary phase voltage u2(t) is converted to the same-side voltage to obtain the converted secondary phase voltage, which is then compared with the primary phase voltage and combined with the rated voltage U in the nameplate parameters. 1N with U 2N Voltage quantities are normalized to unify their dimensions. The primary phase voltage is normalized to... The secondary phase voltage is per-unit scalarized as ,in, Let θ be the per-unit coefficient of the secondary phase voltage amplitude relative to the secondary rated voltage, and θ be the initial phase of the secondary phase voltage. The primary phase voltage u1(t) is determined under the constraint of direct grid connection on the primary side. It is then used in the voltage difference calculation along with the converted secondary phase voltage, expressed on the same side.

[0040] S24: Calculate the voltage difference based on the primary phase voltage and the converted secondary phase voltage, and generate a relationship trajectory based on the voltage difference and the secondary output phase current.

[0041] Specifically, voltage difference is obtained by performing a difference operation on the primary phase voltage and the converted secondary phase voltage under the same sampling time scale, forming voltage difference time series data. Simultaneously, the secondary output phase current and voltage difference are mapped at the same time point to construct a relationship mapping pair. To facilitate the subsequent calculation of trajectory feature variables, the voltage difference and secondary output phase current can be normalized and sinusoidally re-encoded to obtain... ,in The magnitude of the voltage difference. Let θ1 and θ2 be the amplitude of the output current, and let θ1 and θ2 be the initial phases of each. The voltage difference and the output phase current of the secondary side are mapped one-to-one in a rectangular coordinate system and connected in the sampling order to form a relationship trajectory.

[0042] In one embodiment, step S24, namely calculating the voltage difference based on the primary phase voltage and the reduced secondary phase voltage, and generating a relationship trajectory based on the voltage difference and the secondary output phase current, includes: S241: Synchronously sample the primary phase voltage and the converted secondary phase voltage to obtain the voltage alignment sequence of the corresponding sampling points.

[0043] Specifically, the primary phase voltage and the converted secondary phase voltage are synchronously sampled according to a preset sampling frequency, and a uniform sampling time stamp is added to each sampling point. Based on the sampling time stamp, the two voltage sequences are time-aligned to form a one-to-one corresponding voltage alignment sequence, so that u1(t) or under the same sampling time stamp... With u2(t) or This forms a voltage alignment pair for difference calculation, thereby ensuring that the subsequent voltage difference sequence and the output phase current sequence can be mapped accordingly under the same sampling time scale and maintaining the timing consistency of the relationship trajectory.

[0044] S242: Perform difference calculation on the voltage alignment sequence to generate the voltage difference.

[0045] Specifically, for each aligned voltage pair in the voltage alignment sequence, difference calculation is performed and a voltage difference sampling point sequence is generated, such that the voltage difference satisfies the following in the per-unit expression: And can be further rewritten as ,in, The voltage difference amplitude is represented by the amplitude component obtained by frequency domain decomposition of the voltage difference data, and θ1 is the phase parameter corresponding to the voltage difference and has the same phase relationship as the voltage alignment sequence.

[0046] S243: Based on the voltage difference and the secondary side output phase current, a corresponding mapping is performed in a rectangular coordinate system to obtain the relationship trajectory.

[0047] Specifically, the voltage difference Δu and the secondary output phase current i2 at each sampling time point are constructed into point pairs in a Cartesian coordinate system, and point-by-point mapping is performed to obtain a trajectory point set. The trajectory point set is connected according to the sampling time point order to form a relational trajectory, and the relational trajectory exhibits elliptical trajectory characteristics under steady-state conditions to support the determination of feature variables, wherein the elliptical trajectory satisfies the trajectory equation. In the formula and θ1 and θ2 are the voltage difference and the output current amplitude, respectively, and the initial phases of the voltage difference and the output current are the voltage difference and the output current, respectively.

[0048] In one embodiment, in step S30, i.e., constructing a Γ-type equivalent circuit based on nameplate parameters and transformer operating data to estimate excitation impedance and load impedance, and performing load equivalent conversion on the voltage difference based on the excitation impedance and load impedance to obtain the load equivalent voltage difference, the following steps are included: S31: Extract rated voltage, rated current, impedance voltage and load loss from the nameplate parameters to generate an equivalent parameter set.

[0049] Specifically, the primary side rated voltage U is read from the nameplate parameter set. 1N Secondary side rated voltage U 2N Primary side rated current I 1N Secondary side rated current I 2N Impedance voltage U k (%) and load loss P kThe fields are aggregated to form an equivalent parameter set. The rated capacity SN, no-load loss P0, and no-load current I0 (%) are used as supplementary parameters to support the unified description of rated operating conditions and loss terms when modeling the equivalent circuit.

[0050] S32: Construct a Γ-type equivalent circuit based on the equivalent parameter set, and correlate the transformer operating data with the Γ-type equivalent circuit to obtain the impedance estimation input.

[0051] Specifically, a single-phase equivalent circuit of a distribution transformer is constructed based on the equivalent parameter set, and a Γ-type structure is used to merge and map the equivalent parameters, such as... Figure 3 The diagram shown is a single-phase Γ-type equivalent circuit of a distribution transformer, which includes the primary voltage U1, the converted secondary voltage U2′, the primary current I1, the converted secondary current I2′, and the load branch Z. L Establish electrical connections in the Γ-type equivalent circuit, and use the series branch parameter R k With X k Characterizing the equivalent impedance components to correspond Figure 2 The T-type equivalent circuit diagram of a single-phase distribution transformer shown below illustrates the combined effects of the series impedance and the equivalent excitation branch, while also considering... Figure 4 The geometric relationship between voltage phasors, current phasors, and impedance voltage drop phasors in the transformer T-type equivalent circuit diagram shown maps u2(t), i1(t) in the transformer operating data and the voltage and current quantities on the same side obtained by conversion to voltage and current quantities of the Γ-type equivalent circuit input, thereby forming an impedance estimation input that includes voltage, current quantities, and equivalent parameter sets.

[0052] S33: Solve for the excitation impedance and load impedance based on the impedance estimation input to obtain the impedance estimation result.

[0053] Specifically, based on the impedance estimation input, the excitation impedance and load impedance are solved under the constraints of the Γ-type equivalent circuit, and the impedance estimation result is output. The excitation impedance adopts the Z-type equivalent circuit. k Characterized and further decomposed into equivalent resistance component R k With equivalent reactance component X k The load impedance uses Z L Characterized and further decomposed into equivalent resistance component R L With equivalent reactance component X L Z k R k With X k The impedance voltage U from the nameplate parameters k (%), primary side rated voltage U 1N Primary side rated current I 1N With load loss P k Substitution The calculation yields I in the formula. k Take the rated short-circuit current as the reference and compare it with I 1N Consistent, Z L R L With X L The secondary voltage amplitude U2, primary current amplitude I1, and turns ratio k can be substituted from the operating data. The calculation yields θ in the formula. u2 With θ i1 These are the phase parameters of the secondary phase voltage and the primary phase current, respectively.

[0054] S34: Determine the load equivalent conversion relationship based on the impedance estimation results, and perform load equivalent conversion on the voltage difference according to the load equivalent conversion relationship to obtain the load equivalent voltage difference.

[0055] Specifically, the distribution transformer is considered as a linear two-port network, with the primary and secondary currents as excitation sources and the voltage difference ΔU* as the response. Two different load conditions, a and b, are selected, and the corresponding primary and secondary current per-unit quantities are obtained under the same phase. , and , And obtain the per-unit value of the voltage difference between the two sides. and Based on the per-unit current quantities under two sets of load conditions, an equivalent load conversion matrix is ​​constructed, and an equivalent conversion is performed on the voltage difference to obtain a new input-output voltage difference as the equivalent load voltage difference. , In the formula and This is the per-unit current vector of the corresponding side under standard operating conditions, used to uniformly convert the response under different load conditions to the standard operating condition reference, thereby reducing the adverse effects of real-time load fluctuations on subsequent calculations of tilt angle and axis length ratio. The equivalent voltage difference of the load is used as the input for subsequent calculations of elliptical trajectory and monitoring indicators.

[0056] In one embodiment, step S33, namely, solving for the excitation impedance and load impedance based on the impedance estimation input to obtain the impedance estimation result, includes: S331: Extract the voltage and current quantities corresponding to the Γ-type equivalent circuit from the impedance estimation input to generate the impedance solution input.

[0057] Specifically, extracting from the impedance estimation input... Figure 3 The diagram shows the voltage and current quantities corresponding to each node in the Γ-type equivalent circuit of a single-phase distribution transformer, forming the input quantities for impedance calculation. The voltage quantities include the primary voltage U1 and the converted secondary voltage U0. 2′It is associated with the secondary phase voltage u2(t) and its equivalent value on the same side in the operating data, and the current includes the primary current I1 and the equivalent secondary current I. 2′ It is correlated with the primary-side phase current i1(t) in the operating data and its converted secondary-side output phase current. Simultaneously, the voltage and current quantities are extracted for their same-frequency components to obtain amplitude and phase representations, enabling the impedance solution input to participate in subsequent constraint construction in phasor form. and The amplitude parameter and the phase parameter are kept consistent.

[0058] S332: Associate the impedance solution input and the equivalent parameter set to obtain the impedance solution constraints.

[0059] Specifically, the voltage and current quantities in the impedance solution input are compared with U in the equivalent parameter set. k (%), P k U 1N I 1N The impedance solution constraints are constructed by associating the turns ratio k with the impedance ratio k, ensuring that the impedance solution constraints simultaneously satisfy the voltage-current relationship constraints of the Γ-type equivalent circuit and the rated measurement reference constraints defined by the nameplate parameters, while maintaining consistency with the voltage-current relationship constraints of the Γ-type equivalent circuit. Figure 4 The vector relationships in the vector diagram corresponding to the transformer T-type equivalent circuit diagram shown are consistent, where constraints are used to limit Z. k R k X k With Z L R L X L The solvability between them provides a consistent parameter boundary and dimensional reference for subsequent constraint-based solutions of excitation impedance and load impedance.

[0060] S333: Based on the impedance solution constraint, the excitation impedance and load impedance are obtained, and the impedance estimation results are generated.

[0061] Specifically, under impedance solution constraints, the excitation impedance and load impedance are solved and the impedance estimation results are output, so that the excitation impedance is Z... k and its component R k With X k Characterize and satisfy The given by U k The impedance relationship determined by (%), Pk, and rated load is such that the load impedance is related to Z. L and its component R L With X L Characterize and satisfy The impedance relationship given is determined by the voltage and current amplitude and phase difference of the operating data. The impedance estimation results are used in subsequent steps to determine the equivalent load conversion relationship and further used for the stabilization process of the tilt angle and shaft length ratio calculation.

[0062] In one embodiment, step S40, which involves determining the tilt angle and shaft length ratio of the relationship trajectory based on the load equivalent voltage difference and the secondary output phase current, and outputting the winding health status assessment result of the distribution transformer according to the tilt angle and shaft length ratio, includes: S41: Determine the elliptical trajectory corresponding to the relationship trajectory based on the load equivalent voltage difference and the secondary side output phase current.

[0063] Specifically, the load equivalent voltage difference ΔU s The secondary side output phase current and the current are sampled together at the same time scale to construct point pairs and map them to a rectangular coordinate system to form a trajectory point set. The trajectory point sets are then connected according to the sampling order to obtain the elliptical trajectory corresponding to the relational trajectory, ensuring that the elliptical trajectory is mathematically consistent with... The ellipse equations shown are kept consistent to support the subsequent analytical or fitting of characteristic variables. Here, Δu can be replaced by the per-unit expression of the load equivalent voltage difference, and i2* can be replaced by the per-unit expression of the secondary output phase current. The ellipse trajectory is used to characterize the phase coupling and amplitude coupling relationship between the load equivalent voltage difference and the secondary output phase current.

[0064] S42: Determine the tilt angle based on the elliptical trajectory, and determine the major and minor axes of the elliptical trajectory.

[0065] Specifically, the center and principal axis directions of the ellipse are extracted based on the geometric shape of the elliptical trajectory, and the tilt angle θ is obtained. Simultaneously, the axis length parameters corresponding to the major and minor axes of the elliptical trajectory are determined and compared with... Figure 5 The elliptical feature variables in the schematic diagram of the elliptical trajectory curve shown are labeled consistently. The tilt angle θ represents the rotation angle of the ellipse's principal axis relative to the coordinate axes, and 2m and 2n represent the lengths of the major and minor axes of the ellipse, respectively. In the analytical method, the tilt angle θ can be correlated with the Z in the impedance estimation result. k Associate and by Calculate, where |Z k | represents the magnitude of the excitation impedance, arg(Z) k ) is the amplitude of the excitation impedance, so that the tilt angle is consistent with the equivalent impedance characteristics.

[0066] S43: Calculate the shaft length ratio based on the major and minor shafts, and output the winding health status assessment results according to the tilt angle and shaft length ratio.

[0067] Specifically, the axis length ratio τ is calculated based on the major axis parameter m and the minor axis parameter n, and τ=m / n is used as a dual monitoring indicator alongside the tilt angle θ. This is determined analytically according to... Perform the calculation, where |Z k | with arg(Z) k The results are derived from impedance estimation, and θ is the tilt angle. By comparing the real-time calculated θ and τ with the standard values ​​under rated operating conditions and combining them with threshold criteria, the winding health status assessment results are output. As shown in Tables 1 and 2, the tilt angle θ and shaft length ratio τ show significant differences from the healthy operating status under different fault severity levels, and the differences can increase as the fault worsens. As shown in Table 3, under the conditions of sudden load increase and sudden load decrease, θ and τ are basically consistent with the rated operating standard values ​​to indicate the stability of the indicators after load equivalent conversion. Thus, the assessment results are used to indicate the degree of deterioration of the winding inter-turn insulation and support the classification judgment of the winding health status.

[0068] Table 1. Dual monitoring index values ​​under different fault severity (changing short-circuit turns ratio)

[0069] Table 2. Different fault severity levels (changing short-circuit resistance) R f Dual monitoring index values

[0070] Table 3 Dual monitoring index values ​​under different load conditions

[0071] In one embodiment, step S41, namely determining the elliptical trajectory corresponding to the relationship trajectory based on the load equivalent voltage difference and the secondary-side output phase current, includes: S411: Perform Fast Fourier Decomposition on the load equivalent voltage difference and the secondary output phase current to obtain the corresponding fundamental amplitude and fundamental phase information.

[0072] Specifically, Fast Fourier Decomposition is performed on the time-domain sampling sequences of the load equivalent voltage difference and the secondary-side output phase current to extract the fundamental components, and the fundamental amplitude and phase of the load equivalent voltage difference and the secondary-side output phase current are obtained, so that the fundamental amplitude corresponds to... Amplitude parameter ΔU m with I m Or the corresponding amplitude after load equivalent conversion, such that the phase parameters φ1 and φ2 corresponding to the fundamental phase, or their corresponding phases after load equivalent conversion, are respectively.

[0073] S412: Determine the phase difference between the load equivalent voltage difference and the secondary side output phase current based on the fundamental phase information.

[0074] Specifically, based on the fundamental phase information, the phase difference between the fundamental phase of the load equivalent voltage difference and the fundamental phase of the secondary output phase current is calculated, and a phase difference parameter is formed, such that the phase difference is consistent with... The phase difference terms required for cos(θ1-θ2) and sin(θ1-θ2) are kept consistent and can characterize the phase coupling between the voltage difference and the output current.

[0075] S413: Determine the trajectory parameters of the elliptical trajectory based on the fundamental amplitude information and phase difference to obtain the elliptical trajectory.

[0076] Specifically, based on the fundamental amplitude information, the amplitude parameters of the load equivalent voltage difference and the amplitude parameters of the secondary output phase current are determined, and a parameter set for an elliptical trajectory is constructed by combining the phase difference, such that the parameter set includes at least... The required ΔUp*, Ip*, and (θ1-θ2) terms are used to generate or fit the equation of the elliptical trajectory, thereby obtaining the elliptical trajectory corresponding to the relational trajectory in the rectangular coordinate system and making the elliptical trajectory geometrically similar to... Figure 5 In the schematic diagram of the characteristic variables in the elliptical trajectory curve shown, the directions of the principal axis and the major and minor axes of the ellipse are defined in the same way.

[0077] Example 2 like Figure 6 As shown, based on the same inventive concept as the above embodiments, the present invention also provides a distribution transformer winding health status assessment system, comprising: The data acquisition module is used to acquire transformer operating data and corresponding nameplate parameters. The transformer operating data includes primary phase current and secondary phase voltage. The turns ratio conversion module is used to determine the turns ratio based on the nameplate parameters, convert the transformer operating data through the turns ratio to obtain the primary side phase voltage and the secondary side output phase current, convert the secondary side phase voltage to the same side and calculate the voltage difference with the primary side phase voltage, and generate a relationship trajectory based on the voltage difference and the secondary side output phase current. The impedance estimation module is used to construct a Γ-type equivalent circuit based on nameplate parameters and transformer operating data to estimate excitation impedance and load impedance. Based on the excitation impedance and load impedance, the voltage difference is converted to load equivalent to obtain the load equivalent voltage difference. The index evaluation module is used to determine the tilt angle and shaft length ratio of the relationship trajectory based on the load equivalent voltage difference and the secondary output phase current, and output the winding health status evaluation results of the distribution transformer according to the tilt angle and shaft length ratio.

[0078] Optional, the ratio conversion module includes: The turns ratio determination submodule is used to determine the turns ratio based on the rated voltage parameters in the nameplate parameters. The current conversion submodule is used to convert the primary phase current based on the turns ratio to obtain the secondary output phase current; The voltage conversion submodule is used to convert the secondary phase voltage based on the turns ratio to obtain the converted secondary phase voltage, and to determine the primary phase voltage based on the converted secondary phase voltage. The trajectory generation submodule is used to calculate the voltage difference based on the primary phase voltage and the converted secondary phase voltage, and to generate a relationship trajectory based on the voltage difference and the secondary output phase current.

[0079] Optionally, the trajectory generation submodule includes: The synchronous sampling unit is used to synchronously sample the primary phase voltage and the converted secondary phase voltage to obtain the voltage alignment sequence of the corresponding sampling points; The difference calculation unit is used to perform difference calculation on the voltage alignment sequence to generate the voltage difference; The coordinate mapping unit is used to perform corresponding mapping based on the voltage difference and the secondary side output phase current in a rectangular coordinate system to obtain the relationship trajectory.

[0080] Optionally, the impedance estimation module includes: The parameter extraction submodule is used to extract rated voltage, rated current, impedance voltage and load loss from the nameplate parameters and generate an equivalent parameter set; The circuit construction submodule is used to construct a Γ-type equivalent circuit based on the equivalent parameter set, and to correlate the transformer operating data with the Γ-type equivalent circuit to obtain the impedance estimation input; The impedance calculation submodule is used to solve for the excitation impedance and load impedance based on the impedance estimation input, and obtain the impedance estimation result. The equivalent conversion submodule is used to determine the load equivalent conversion relationship based on the impedance estimation results, and to perform load equivalent conversion on the voltage difference according to the load equivalent conversion relationship to obtain the load equivalent voltage difference.

[0081] Optionally, the impedance solving submodule includes: The input extraction unit is used to extract the voltage and current quantities corresponding to the Γ-type equivalent circuit from the impedance estimation input, and generate the impedance solution input quantities. Constraint building units are used to associate impedance solution inputs and equivalent parameter sets to obtain impedance solution constraints; The constraint solving unit is used to obtain the excitation impedance and load impedance based on the impedance solving constraint, and generate impedance estimation results.

[0082] Optional, the indicator evaluation module includes: The ellipse determination submodule is used to determine the ellipse trajectory corresponding to the relationship trajectory based on the load equivalent voltage difference and the secondary side output phase current. The parameter extraction submodule is used to determine the tilt angle based on the elliptical trajectory, and to determine the major and minor axes of the elliptical trajectory. The ratio calculation submodule is used to calculate the shaft length ratio based on the major and minor axes, and output the winding health status assessment results according to the tilt angle and shaft length ratio.

[0083] Optionally, the ellipse determination submodule includes: The frequency domain decomposition unit is used to perform fast Fourier decomposition on the load equivalent voltage difference and the secondary side output phase current to obtain the corresponding fundamental amplitude information and fundamental phase information. The phase determination unit is used to determine the phase difference between the load equivalent voltage difference and the secondary side output phase current based on the fundamental phase information. The parameter calculation unit is used to determine the trajectory parameters of the elliptical trajectory based on the fundamental amplitude information and phase difference, so as to obtain the elliptical trajectory.

[0084] Example 3 like Figure 7 As shown, the present invention also provides an electronic device 100 for implementing a method for assessing the health status of distribution transformer windings; The electronic device 100 includes a memory 101, at least one processor 102, a computer program 103 stored in the memory 101 and executable on at least one processor 102, and at least one communication bus 104.

[0085] The memory 101 can be used to store the computer program 103. The processor 102 implements the steps of the method for assessing the health status of a distribution transformer winding in Embodiment 1 by running or executing the computer program stored in the memory 101 and calling the data stored in the memory 101.

[0086] The memory 101 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs required for at least one function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created based on the use of the electronic device 100 (such as audio data), etc. In addition, the memory 101 may include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other non-volatile solid-state storage device.

[0087] At least one processor 102 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Processor 102 may be a microprocessor or any conventional processor. Processor 102 is the control center of electronic device 100, connecting various parts of electronic device 100 via various interfaces and lines.

[0088] The memory 101 in the electronic device 100 stores multiple instructions to implement a method for assessing the health status of a distribution transformer winding, and the processor 102 can execute multiple instructions to achieve the following: Obtain transformer operating data and corresponding nameplate parameters. Transformer operating data includes primary phase current and secondary phase voltage. The turns ratio is determined based on the nameplate parameters. The transformer operating data is converted using the turns ratio to obtain the primary side phase voltage and the secondary side output phase current. The secondary side phase voltage is converted to the same side and the voltage difference is calculated with the primary side phase voltage. The relationship trajectory is generated based on the voltage difference and the secondary side output phase current. Based on the nameplate parameters and transformer operating data, a Γ-type equivalent circuit is constructed to estimate the excitation impedance and load impedance. The load equivalent voltage difference is then calculated based on the excitation impedance and load impedance to obtain the load equivalent voltage difference. The tilt angle and shaft length ratio of the relationship trajectory are determined based on the load equivalent voltage difference and the secondary output phase current, and the winding health status assessment results of the distribution transformer are output according to the tilt angle and shaft length ratio.

[0089] Example 4 If the modules / units integrated in the electronic device 100 are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or system capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, and read-only memory (ROM).

[0090] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0091] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A system that specifies functions in one or more boxes.

[0092] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including an instruction set implemented in a process. Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0093] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0094] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for assessing the health status of distribution transformer windings, characterized in that, The method includes: Acquire transformer operating data and corresponding nameplate parameters, wherein the transformer operating data includes primary phase current and secondary phase voltage; The turns ratio is determined based on the nameplate parameters. The transformer operating data is then converted using the turns ratio to obtain the primary phase voltage and the secondary output phase current. The secondary phase voltage is converted to the same side and the voltage difference is calculated with the primary phase voltage. A relationship trajectory is generated based on the voltage difference and the secondary output phase current. Based on the nameplate parameters and the transformer operating data, a Γ-type equivalent circuit is constructed to estimate the excitation impedance and load impedance. The voltage difference is then converted to a load equivalent voltage difference based on the excitation impedance and load impedance. The tilt angle and shaft length ratio of the relationship trajectory are determined based on the load equivalent voltage difference and the secondary output phase current, and the winding health status assessment result of the distribution transformer is output according to the tilt angle and the shaft length ratio.

2. The method for assessing the health status of distribution transformer windings according to claim 1, characterized in that, The process of determining the turns ratio based on the nameplate parameters, calculating the transformer operating data using the turns ratio to obtain the primary side phase voltage and secondary side output phase current, calculating the voltage difference between the secondary side phase voltage (after converting it to the same side) and the primary side phase voltage, and generating a relationship trajectory based on the voltage difference and the secondary side output phase current includes: The turns ratio is determined based on the rated voltage parameter in the nameplate parameters. The primary phase current is calculated based on the transformer ratio to obtain the secondary output phase current; The secondary phase voltage is calculated based on the turns ratio to obtain the calculated secondary phase voltage, and the primary phase voltage is determined based on the calculated secondary phase voltage. The voltage difference is calculated based on the primary phase voltage and the converted secondary phase voltage, and the relationship trajectory is generated based on the voltage difference and the secondary output phase current.

3. The method for assessing the health status of distribution transformer windings according to claim 2, characterized in that, The step of calculating the voltage difference based on the primary phase voltage and the reduced secondary phase voltage, and generating the relationship trajectory based on the voltage difference and the secondary output phase current, includes: The primary phase voltage and the converted secondary phase voltage are sampled synchronously to obtain the voltage alignment sequence of the corresponding sampling points; Perform difference calculation on the voltage alignment sequence to generate the voltage difference; The relationship trajectory is obtained by mapping the voltage difference and the secondary output phase current in a rectangular coordinate system.

4. The method for assessing the health status of distribution transformer windings according to claim 1, characterized in that, The process of constructing a Γ-type equivalent circuit based on the nameplate parameters and the transformer operating data to estimate the excitation impedance and load impedance, and performing a load equivalent conversion on the voltage difference based on the excitation impedance and the load impedance to obtain the load equivalent voltage difference includes: The rated voltage, rated current, impedance voltage, and load loss are extracted from the nameplate parameters to generate an equivalent parameter set; The Γ-type equivalent circuit is constructed based on the equivalent parameter set, and the transformer operating data and the Γ-type equivalent circuit are correlated to obtain the impedance estimation input; Based on the impedance estimation input, the excitation impedance and the load impedance are solved to obtain the impedance estimation result; Based on the impedance estimation results, the load equivalent conversion relationship is determined, and the voltage difference is converted according to the load equivalent conversion relationship to obtain the load equivalent voltage difference.

5. The method for assessing the health status of distribution transformer windings according to claim 4, characterized in that, The process of solving for the excitation impedance and the load impedance based on the impedance estimation input to obtain the impedance estimation result includes: The voltage and current quantities corresponding to the Γ-type equivalent circuit are extracted from the impedance estimation input to generate the impedance solution input. By associating the impedance solution input with the equivalent parameter set, impedance solution constraints are obtained. The excitation impedance and the load impedance are obtained by solving the impedance constraints, and the impedance estimation result is generated.

6. The method for assessing the health status of distribution transformer windings according to claim 1, characterized in that, The process of determining the tilt angle and shaft length ratio of the relationship trajectory based on the equivalent voltage difference of the load and the output phase current of the secondary side, and outputting the winding health status assessment result of the distribution transformer according to the tilt angle and the shaft length ratio, includes: The elliptical trajectory corresponding to the relationship trajectory is determined based on the load equivalent voltage difference and the secondary side output phase current. The tilt angle is determined based on the elliptical trajectory, and the major and minor axes of the elliptical trajectory are also determined. The axis length ratio is calculated based on the major axis and the minor axis, and the winding health status assessment result is output according to the tilt angle and the axis length ratio.

7. The method for assessing the health status of distribution transformer windings according to claim 6, characterized in that, The step of determining the elliptical trajectory corresponding to the relationship trajectory based on the equivalent voltage difference of the load and the output phase current of the secondary side includes: Fast Fourier decomposition is performed on the equivalent voltage difference of the load and the output phase current of the secondary side to obtain the corresponding fundamental amplitude information and fundamental phase information; The phase difference between the load equivalent voltage difference and the secondary side output phase current is determined based on the fundamental phase information. The trajectory parameters of the elliptical trajectory are determined based on the fundamental amplitude information and the phase difference to obtain the elliptical trajectory.

8. A system for assessing the health status of distribution transformer windings, characterized in that, The system includes: The data acquisition module is used to acquire transformer operating data and corresponding nameplate parameters. The transformer operating data includes primary phase current and secondary phase voltage. The turns ratio conversion module is used to determine the turns ratio based on the nameplate parameters, convert the transformer operating data through the turns ratio to obtain the primary side phase voltage and the secondary side output phase current, convert the secondary side phase voltage to the same side and calculate the voltage difference with the primary side phase voltage, and generate a relationship trajectory based on the voltage difference and the secondary side output phase current. The impedance estimation module is used to construct a Γ-type equivalent circuit based on nameplate parameters and transformer operating data to estimate excitation impedance and load impedance. Based on the excitation impedance and load impedance, the voltage difference is converted to load equivalent to obtain the load equivalent voltage difference. The index evaluation module is used to determine the tilt angle and shaft length ratio of the relationship trajectory based on the load equivalent voltage difference and the secondary output phase current, and output the winding health status evaluation results of the distribution transformer according to the tilt angle and shaft length ratio.

9. An electronic device, characterized in that, It includes a processor and a memory, the processor being used to execute a computer program stored in the memory to implement the steps of the distribution transformer winding health status assessment method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one instruction, which, when executed by a processor, implements the steps of the distribution transformer winding health status assessment method as described in any one of claims 1 to 7.

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