Transformer winding state evaluation method and transformer winding state evaluation platform

Abstract

The embodiment of the invention discloses a transformer winding state evaluation method and a transformer winding state evaluation platform. The method comprises the following steps: acquiring an input electric signal of a primary winding and an output electric signal of a secondary winding of a target transformer under high-frequency excitation signals with different frequencies; calculating and fitting according to the input electric signal and the output electric signal of the target transformer under the high-frequency excitation signals with different frequencies to obtain an operation parameter curve of the target transformer; and performing characteristic analysis based on the operation parameter curve and evaluating the winding state of the target transformer. An operation parameter curve is generated through calculation and fitting of an input electric signal and an output electric signal of a target transformer under high-frequency excitation signals with different frequencies, and the operation state of a transformer winding is judged accordingly, so that potential faults of the transformer can be found in time, a more scientific maintenance plan is made, and the maintenance efficiency is improved. The equipment can be ensured to be in an optimal working state, budget can be reasonably arranged, and resource waste caused by excessive maintenance is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer monitoring, and in particular to a transformer winding state assessment method and a transformer winding state assessment platform. Background Art

[0002] Transformers play a vital role in the power grid. They are responsible for adjusting the electricity generated by power plants to a voltage level suitable for long-distance transmission or local distribution. Therefore, the reliability of the transformer directly affects the overall performance of the power system. The winding is one of the main components inside the transformer. Its integrity directly determines the working efficiency and safety of the transformer.

[0003] The significance of transformer winding condition assessment is not only to prevent possible failures, but more importantly, to avoid sudden service interruptions by identifying potential problems early, which is crucial to maintaining the continuity and reliability of power supply. For example, some common winding problems such as aging of insulation materials, deformation caused by short circuits, or overheating due to overload may become the root cause of future failures. At present, there is no effective method to assess the condition of transformer windings. Summary of the invention

[0004] Based on this, it is necessary to propose a transformer winding status assessment method and a transformer winding status assessment platform to address the above problems in order to effectively assess the status of the transformer winding.

[0005] To achieve the above-mentioned object, the present application provides, in a first aspect, a method for evaluating the state of a transformer winding, the method comprising:

[0006] Injecting high-frequency excitation signals of different frequencies into the target transformer through a preset signal injection method;

[0007] Acquire an input electrical signal of the primary winding and an output electrical signal of the secondary winding of the target transformer under high-frequency excitation signals of different frequencies;

[0008] Calculating and fitting the input electrical signal and the output electrical signal of the target transformer under high-frequency excitation signals of different frequencies to obtain an operating parameter curve of the target transformer;

[0009] A characteristic analysis is performed based on the operating parameter curve to evaluate the winding state of the target transformer.

[0010] Furthermore, the electrical signal includes voltage data and current data, and the input electrical signal and the output electrical signal of the target transformer under the high-frequency excitation signals of different frequencies are calculated and fitted to obtain the operating parameter curve of the target transformer, specifically including:

[0011] The first operating parameter values ​​corresponding to different frequencies are calculated according to the input voltage data of the primary winding and the output current data of the secondary winding of the target transformer under the high-frequency excitation signals of different frequencies, and the first operating parameter curve of the target transformer is obtained by fitting based on the first operating parameter values ​​corresponding to the different frequencies;

[0012] According to the input current data of the primary winding and the output voltage data of the secondary winding of the target transformer under the high-frequency excitation signals of different frequencies, the second operating parameter values ​​corresponding to the different frequencies are calculated, and the second operating parameter curve of the target transformer is obtained by fitting based on the second operating parameter values ​​corresponding to the different frequencies;

[0013] Among them, the independent variable of the operating parameter curve is ln f i , the dependent variable is

[0014] In the formula, f i is the target frequency, which is any frequency within a preset frequency range, U(i) is the input voltage data or output voltage data under the high-frequency excitation signal of the target frequency, and I(i) is the input current data or output current data under the high-frequency excitation signal of the target frequency.

[0015] Further, the performing feature analysis based on the operating parameter curve and evaluating the winding state of the target transformer specifically includes:

[0016] Performing characteristic analysis based on the first operating parameter curve and the second operating parameter curve to obtain a first operating characteristic value and a second operating characteristic value;

[0017] Calculate a first deformation assessment factor and a second deformation assessment factor according to the first operation characteristic value and the second operation characteristic value;

[0018] A comprehensive evaluation is performed according to the first deformation assessment factor and the second deformation assessment factor to determine the winding state of the target transformer.

[0019] Further, the calculating the first deformation assessment factor and the second deformation assessment factor according to the first operation characteristic value and the second operation characteristic value specifically includes:

[0020] Performing Fourier decomposition on target input current data, target input voltage data, target output current data, and target output voltage data to obtain reference phases of the target input current data, the target input voltage data, the target output current data, and the target output voltage data, respectively, wherein the target input current data, the target input voltage data, the target output current data, and the target output voltage data are respectively input current data, input voltage data, output current data, and output voltage data under a high-frequency excitation signal of the target frequency;

[0021] Calculating a current phase difference corresponding to the target frequency according to a reference phase of the target input current data and the target output current data;

[0022] Calculating a voltage phase difference corresponding to the target frequency according to a reference phase of the target input voltage data and the target output voltage data;

[0023] The first deformation assessment factor and the second deformation assessment factor are calculated according to the current phase difference, the voltage phase difference, the first operation characteristic value, and the second operation characteristic value.

[0024] Furthermore, the operation characteristic value includes an average value and a maximum value of the operation parameter value, and the first deformation assessment factor and the second deformation assessment factor are obtained by fitting and calculating the following formula:

[0025]

[0026] Where Ψ1 and Ψ2 are the deformation factors of the first winding and the second winding, respectively. i is the target frequency, 1≤i≤N, N is the total number of frequency values, Y 1max is the maximum value of all first run parameter values, is the voltage phase difference corresponding to the target frequency, is the current phase difference corresponding to the target frequency, Y 1(i) is the first operating parameter value at the target frequency, Y 1av is the average of all first run parameter values, Y 2max is the maximum value of all second frequency response values, Y 2(i) is the second operating parameter value at the target frequency, Y 2av is the average of all second run parameter values.

[0027] Furthermore, the signal injection methods include voltage transformer injection, capacitance sensor injection, and station transformer injection;

[0028] The step of performing a comprehensive evaluation according to the first deformation evaluation factor and the second deformation evaluation factor to determine the winding state of the target transformer specifically includes:

[0029] Calculate the comprehensive evaluation coefficient according to the first deformation evaluation factor and the second deformation evaluation factor under three signal injection modes of voltage transformer, capacitance sensor and station transformer;

[0030] A winding state of the target transformer is determined based on the comprehensive evaluation coefficient.

[0031] Furthermore, the comprehensive evaluation coefficient is calculated by the following formula:

[0032]

[0033] In the formula, Ψ 1(a) ,Ψ 1(b) ,Ψ 1(c) are the first deformation assessment factors under voltage transformer injection, capacitance sensor injection and station transformer injection, Ψ 2(a) ,Ψ 2(b) ,Ψ 2(c) They are the second deformation assessment factors under voltage transformer injection, capacitance sensor injection and station transformer injection respectively.

[0034] Further, determining the deformation condition of the transformer winding to be monitored based on the comprehensive evaluation coefficient specifically includes:

[0035] If the comprehensive evaluation coefficient is greater than the preset coefficient threshold, the transformer winding to be monitored is in good condition;

[0036] If the comprehensive evaluation coefficient is not greater than the coefficient threshold, then there is a fault in the transformer winding to be monitored.

[0037] To achieve the above-mentioned purpose, the second aspect of the present application provides a transformer winding state evaluation platform, which includes a host PC, a main control board, a DC voltage source, a switch tube, a protection resistor, a coupling coil, a signal injection module, an injection current detector, an injection voltage detector, a target transformer, an output voltage detector, a capacitor, an output current detector, an equivalent impedance, and an industrial frequency power supply device;

[0038] The host PC end is connected to the main control board, the main control board is connected to the switch tube, and the switch tube is respectively connected to the DC voltage source and the coupling coil; the DC voltage source is connected to the protection resistor, and the coupling coil is respectively connected to the protection resistor and the signal injection module; the signal injection module is connected to the injection current detector, the injection current detector is connected to the injection voltage detector, the injection voltage detector is connected to the target transformer, the target transformer is respectively connected to the output voltage detector, the capacitor and the equivalent resistor, the capacitor is connected to the output current detector, the equivalent resistor is connected to the industrial frequency power supply device, and the industrial frequency power supply device is connected to the host PC end.

[0039] Furthermore, the host PC sends an evaluation command to the main control board, and the main control board controls the switch tube to continuously switch the frequency and open the switch according to the evaluation command, so that the DC voltage source outputs high-frequency excitation signals of different frequencies, and the high-frequency excitation signal flows into the coupling coil through the protection resistor, and the coupling coil couples the high-frequency excitation signal to obtain a coupled high-frequency signal, and the signal injection module injects the coupled high-frequency signal into the primary winding of the target transformer; the injection current detector and the injection voltage detector respectively collect the input current data and input voltage data of the primary winding of the target transformer, and the output voltage detector and the output current detector respectively collect the output voltage data and output current data of the secondary winding of the target transformer, the capacitance and the equivalent impedance are peripheral electrical parameters of the target transformer, and the industrial frequency power supply device calculates and fits the input voltage data, input current data, output current data and output voltage data of the target transformer under high-frequency excitation signals of different frequencies to obtain an operating parameter curve of the target transformer; based on the operating parameter curve, feature analysis is performed and the winding state of the target transformer is evaluated, and the winding state of the target transformer is sent to the host PC.

[0040] The embodiments of the present invention have the following beneficial effects:

[0041] The embodiment of the present invention proposes a state assessment method for transformer windings, the method comprising: injecting high-frequency excitation signals of different frequencies into a target transformer through a preset signal injection method; obtaining the input electrical signal of the primary winding and the output electrical signal of the secondary winding of the target transformer under high-frequency excitation signals of different frequencies; calculating and fitting the input electrical signal and the output electrical signal of the target transformer under high-frequency excitation signals of different frequencies to obtain an operating parameter curve of the target transformer; and performing feature analysis and evaluating the winding state of the target transformer based on the operating parameter curve. The normal operation of the transformer is simulated based on the high-frequency excitation signal, and there is no need for offline detection and shutdown for inspection, which does not affect the normal production and operation of the power grid; in addition, the operating parameter curve is calculated and fitted based on the input electrical signal and the output electrical signal of the target transformer under high-frequency excitation signals of different frequencies, and the operating state of the transformer winding is judged based on this, so that the potential faults of the transformer can be discovered in time, so as to formulate a more scientific maintenance plan, which can not only ensure that the equipment is in the best working state, but also reasonably arrange the budget and avoid the waste of resources caused by excessive maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] in:

[0044] Figure 1 A transformer winding status assessment platform built for an embodiment of the present invention;

[0045] Figure 2 Schematic diagram of a flow chart of a transformer winding status assessment method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The present invention provides a transformer winding state assessment method, which is implemented based on a transformer winding state assessment platform (19). Figure 1 , Figure 1A transformer winding state evaluation platform (19) is constructed for an embodiment of the present invention. The platform (19) comprises a host PC end (1), a main control board (2), a DC voltage source (3), a switch tube (4), a protection resistor (5), a coupling coil (6), a signal injection module (7), an injection current detector (11), an injection voltage detector (12), a target transformer (13), an output voltage detector (14), a capacitor (15), an output current detector (16), an equivalent impedance (17), and an industrial frequency power supply device (18); the host PC end (1) is connected to the main control board (2), the main control board (2) is connected to the switch tube (4), and the switch tube (4) is respectively connected to the DC voltage source (3) and the coupling coil (6). The coupling coil (6) is connected; the DC voltage source (3) is connected to the protection resistor (5), the coupling coil (6) is respectively connected to the protection resistor (5) and the signal injection module (7); the signal injection module (7) is connected to the injection current detector (11), the injection current detector (11) is connected to the injection voltage detector (12), the injection voltage detector (12) is connected to the target transformer (13), the target transformer (13) is respectively connected to the output voltage detector (14), the capacitor (15) and the equivalent resistor, the capacitor (15) is connected to the output current detector (16), the equivalent resistor is connected to the power frequency power supply device (18), and the power frequency power supply device (18) is connected to the host PC end (1).

[0048] In one embodiment of the present invention, a host PC terminal (1) sends an evaluation command to a main control board (2). The main control board (2) controls a switch tube (4) to continuously switch frequencies and open and close switches according to the evaluation command, so that a DC voltage source (3) outputs high-frequency excitation signals of different frequencies. The high-frequency excitation signal flows into a coupling coil (6) through a protection resistor (5). The coupling coil (6) couples the high-frequency excitation signal to obtain a coupled high-frequency signal. The signal injection module (7) injects the coupled high-frequency signal into a primary winding of a target transformer (13). An injection current detector (11) and an injection voltage detector (12) respectively collect input current data and input voltage data of the primary winding of the target transformer (13), and outputs the high-frequency excitation signal. The voltage detector (14) and the output current detector (16) respectively collect the output voltage data and the output current data of the secondary winding of the target transformer (13); the capacitor (15) and the equivalent impedance (17) are the peripheral electrical parameters of the target transformer (13); the industrial frequency power supply device (18) calculates and fits the input voltage data, input current data, output current data and output voltage data of the target transformer (13) under high-frequency excitation signals of different frequencies to obtain an operating parameter curve of the target transformer (13); based on the operating parameter curve, feature analysis is performed to evaluate the winding state of the target transformer (13), and the winding state of the target transformer (13) is sent to the host PC end (1).

[0049] Specifically, the host PC end (1) is responsible for issuing evaluation commands, and the main control board (2) receives the evaluation commands from the host PC end (1) to control the switch tube (4) to continuously switch the frequency, as well as the opening and closing of the switch. In this process, the DC voltage source (3) obtains a high-frequency excitation signal with an arbitrarily adjustable frequency due to the continuous opening and closing of the switch tube (4).

[0050] In the high-frequency signal generating circuit, the protective resistor (5) is used to ensure the circuit safety; the coupling coil (6) is used to couple the high-frequency excitation signal to the injection side of the winding of the target transformer (13), that is, the primary winding, and inject the coupled high-frequency excitation signal into the primary winding of the target transformer (13) through the signal injection module (7). In one embodiment of the present invention, the signal injection module (7) includes a capacitance sensor (8), a station transformer (9) and a voltage transformer (10), and injects the high-frequency excitation signal into the primary winding of the target transformer (13) through three different injection methods: the capacitance sensor (8), the station transformer (9) and the voltage transformer (10).

[0051] The injected current detector (11) and the injected voltage detector (12) respectively measure the injected current and voltage; the output voltage detector (14) and the output current detector (16) respectively measure the output voltage and current at the secondary winding of the target transformer (13); the capacitance (15) and the equivalent impedance (17) are some peripheral electrical parameters of the target transformer (13) experimental object.

[0052] The industrial frequency power supply device (18) is used to simulate the normal working condition of the target transformer (13). First, by recording the input and output electrical signals under three high-frequency excitation signal injection modes, such as input voltage data, input current data, output voltage data and output current data, and then calculating and fitting according to the input voltage data, input current data, output current data and output voltage data, an operating parameter curve of the target transformer (13) is obtained; based on the operating parameter curve, a characteristic analysis is performed and the winding state of the target transformer (13) is evaluated, and the winding state of the target transformer (13) is sent to the host PC end (1), so that the detection personnel can timely understand the current state of the target transformer (13).

[0053] The present invention also provides a transformer winding status assessment method, which can be referred to as Figure 2 , Figure 2 : is a flow chart of a transformer winding state assessment method in an embodiment of the present invention, the method comprising:

[0054] Step 210: Inject high-frequency excitation signals of different frequencies into the target transformer through a preset signal injection method.

[0055] In an embodiment of the present invention, a high-frequency excitation signal is injected into a target transformer to detect winding deformation. The excitation signal is a signal injected into the target transformer, which is intended to cause the target transformer to respond, and the high-frequency excitation signal refers to an excitation signal with a higher frequency. When a high-frequency excitation signal is used, the ultrasonic wave generated has a short wavelength, a small diffusion angle, and concentrated energy, which makes the high-frequency excitation signal have a higher resolution during detection. In addition, the generation and regulation of high-frequency excitation signals are relatively flexible, and different signal characteristics can be achieved by adjusting circuit parameters, waveforms, etc., so that the high-frequency excitation signal can adapt to different application scenarios and requirements. The high-frequency excitation signal can also realize non-contact detection, avoiding damage or interference that may be caused by contact, and improving the reliability and safety of detection.

[0056] Specifically, the main control board (2) controls the switch tube (4) to continuously switch the frequency and turn the switch on and off according to the evaluation command. In this process, the DC voltage source (3) obtains high-frequency excitation signals of different frequencies due to the continuous turning on and off of the switch tube (4), and the signal injection module (7) injects the high-frequency excitation signals of different frequencies into the target transformer respectively.

[0057] Step 220: Acquire the input electrical signal of the primary winding and the output electrical signal of the secondary winding of the target transformer under high-frequency excitation signals of different frequencies.

[0058] Specifically, the electrical signal may be current and voltage. The input current data and input voltage data of the primary winding of the target transformer may be measured by an injection current detector (11) and an injection voltage detector (12); the output voltage data and output current data of the secondary winding of the target transformer may be measured by an output voltage detector (14) and an output current detector (16).

[0059] Step 230: Calculate and fit the input electrical signal and the output electrical signal of the target transformer under high-frequency excitation signals of different frequencies to obtain an operating parameter curve of the target transformer.

[0060] In an embodiment of the present invention, the operating condition of the target transformer is observed by measuring the voltage and current of the primary winding and the secondary winding of the target transformer under high-frequency excitation signals of different frequencies, and the operating parameters reflecting the operating condition of the target transformer are obtained for data fitting to obtain the operating parameter curve of the target transformer, so as to evaluate the winding state based on the operating curve.

[0061] Step 240: Perform feature analysis based on the operating parameter curve and evaluate the winding state of the target transformer.

[0062] Specifically, the operating characteristics of the target transformer are obtained based on the operating parameter curve analysis of the target transformer, and the winding state of the target transformer is evaluated according to the operating characteristics.

[0063] In the embodiment of the present invention, by regularly evaluating the transformer winding status, winding failures can be discovered early, and corresponding active measures can be taken to repair or replace the transformer to prevent the failure from escalating into a catastrophic event.

[0064] In one embodiment of the present invention, step 230, calculating and fitting the input electrical signal and the output electrical signal of the target transformer under high-frequency excitation signals of different frequencies to obtain the operating parameter curve of the target transformer, specifically includes:

[0065] Step 310, calculate the first operating parameter values ​​corresponding to different frequencies according to the input voltage data of the primary winding and the output current data of the secondary winding of the target transformer under the high-frequency excitation signals of different frequencies, and perform fitting based on the first operating parameter values ​​corresponding to different frequencies to obtain the first operating parameter curve of the target transformer.

[0066] Step 320, calculating the second operating parameter values ​​corresponding to different frequencies according to the input current data of the primary winding and the output voltage data of the secondary winding of the target transformer under the high-frequency excitation signals of different frequencies, and fitting based on the second operating parameter values ​​corresponding to the different frequencies to obtain the second operating parameter curve of the target transformer;

[0067] Among them, the independent variable of the operating parameter curve is kn f i , the dependent variable is

[0068] In the formula, f i is the target frequency, the target frequency is any frequency within the preset frequency range, U(i) is the input voltage data or output voltage data under the high-frequency excitation signal of the target frequency, and I(i) is the input current data or output current data under the high-frequency excitation signal of the target frequency.

[0069] In the embodiment of the present invention, the switching frequency f of the switch tube (4) is controlled by the main control board (2). i (i=1,2……N; the unit of f is Hz); the horizontal axis is ln f i The vertical axes are and Among them, I o (i) is the output current data, U in (i) is the input voltage data, I in (i) is the input current data, U o (i) is the output voltage data. Finally, the transformer simulation operation parameter curve is drawn according to the horizontal and vertical coordinates.

[0070] In one embodiment of the present invention, step 240, performing feature analysis based on the operating parameter curve and evaluating the winding state of the target transformer, specifically includes:

[0071] Step 410: Perform characteristic analysis based on the first operating parameter curve and the second operating parameter curve to obtain a first operating characteristic value and a second operating characteristic value.

[0072] In the embodiment of the present invention, the operating characteristic value may be an average value, a maximum value, a minimum value, etc. of the operating parameter value.

[0073] Step 420: Calculate a first deformation assessment factor and a second deformation assessment factor according to the first operation characteristic value and the second operation characteristic value.

[0074] A deformation assessment factor for assessing whether deformation occurs in the target transformer winding is calculated respectively by using the first operation characteristic value and the second operation characteristic value.

[0075] In one embodiment of the present invention, Step 420, calculating the first deformation assessment factor and the second deformation assessment factor according to the first operation characteristic value and the second operation characteristic value, specifically includes:

[0076] Step 421. Perform Fourier decomposition on the target input current data, target input voltage data, target output current data and target output voltage data to obtain the reference phases of the target input current data, target input voltage data, target output current data and target output voltage data, respectively. The target input current data, target input voltage data, target output current data and target output voltage data are respectively the input current data, input voltage data, output current data and output voltage data under the high-frequency excitation signal of the target frequency.

[0077] Specifically, Fourier decomposition is performed on the waveforms of the measured input voltage data, input current data, output voltage data, and output current data to obtain a reference phase of each data.

[0078] Step 422, calculate the current phase difference corresponding to the target frequency according to the reference phase of the target input current data and the target output current data.

[0079] Step 423, calculate the voltage phase difference corresponding to the target frequency according to the reference phase of the target input voltage data and the target output voltage data.

[0080] Step 424, calculating a first deformation assessment factor and a second deformation assessment factor according to the current phase difference, the voltage phase difference, the first operation characteristic value and the second operation characteristic value.

[0081] In one embodiment of the present invention, the operation characteristic value includes an average value and a maximum value of the operation parameter value, and the first deformation assessment factor and the second deformation assessment factor are obtained by fitting and calculating the following formula:

[0082]

[0083] Where Ψ1 and Ψ2 are the deformation factors of the first winding and the second winding, respectively. i is the target frequency, 1≤i≤N, N is the total number of frequency values, Y 1max is the maximum value of all first run parameter values, is the voltage phase difference corresponding to the target frequency, is the current phase difference corresponding to the target frequency, Y 1(i) is the first operating parameter value at the target frequency, Y 1av is the average of all first run parameter values, Y 2max is the maximum value of all second frequency response values, Y 2(i) is the second operating parameter value at the target frequency, Y 2av is the average of all second run parameter values.

[0084] Step 430: Perform a comprehensive evaluation based on the first deformation evaluation factor and the second deformation evaluation factor to determine the winding state of the target transformer.

[0085] In the embodiment of the present invention, a comprehensive evaluation is performed on the winding condition of the transformer to be monitored according to the first deformation evaluation factor and the second deformation evaluation factor to reduce the error of the evaluation result.

[0086] In one embodiment of the present invention, the signal injection module (7) includes a voltage transformer (10), a capacitance sensor (8) and a station transformer (9). Then the signal injection method includes voltage transformer (10) injection, capacitance sensor (8) injection and station transformer (9) injection; based on this, Step 430, a comprehensive evaluation is performed according to the first deformation assessment factor and the second deformation assessment factor to determine the winding state of the target transformer, specifically including:

[0087] Step 431, calculate the comprehensive evaluation coefficient according to the first deformation evaluation factor and the second deformation evaluation factor under the three signal injection modes of voltage transformer, capacitance sensor and station transformer.

[0088] In one embodiment of the present invention, the comprehensive evaluation coefficient is calculated by the following formula:

[0089]

[0090] In the formula, Ψ 1(a) ,Ψ 1(b) ,Ψ 1(c)are the first deformation assessment factors under voltage transformer injection, capacitance sensor injection and station transformer injection, Ψ 2(a) , 2(b) , 2(c) They are the second deformation assessment factors under voltage transformer injection, capacitance sensor injection and station transformer injection respectively.

[0091] Step 432, determine the winding state of the target transformer based on the comprehensive evaluation coefficient.

[0092] Specifically, if the comprehensive evaluation coefficient is greater than a preset coefficient threshold, the transformer winding to be monitored is in good condition; if the comprehensive evaluation coefficient is not greater than the coefficient threshold, the transformer winding to be monitored is faulty.

[0093] For example, the coefficient threshold may be 0.78. If the comprehensive evaluation coefficient is greater than 0.78, it indicates that the transformer winding is in good condition and can continue to operate. If the comprehensive evaluation coefficient is less than or equal to 0.78, it indicates that the transformer winding is faulty and the power should be shut down for maintenance in a timely manner.

[0094] The transformer winding status assessment method proposed in the present invention simulates the normal operation of the transformer based on a high-frequency excitation signal. There is no need for offline detection and shutdown for inspection, and the normal production and operation of the power grid is not affected. In addition, the input electrical signal and output electrical signal of the target transformer under high-frequency excitation signals of different frequencies are calculated and fitted to generate an operating parameter curve, and the operating status of the transformer winding is judged based on this, so that potential faults of the transformer can be discovered in time, so as to formulate a more scientific maintenance plan, which can not only ensure that the equipment is in the best working condition, but also reasonably arrange the budget and avoid waste of resources caused by excessive maintenance.

Claims

1. A method for evaluating the state of a transformer winding, characterized in that: The method comprises: Injecting high-frequency excitation signals of different frequencies into the target transformer through a preset signal injection method; Acquire an input electrical signal of the primary winding and an output electrical signal of the secondary winding of the target transformer under high-frequency excitation signals of different frequencies; Calculating and fitting the input electrical signal and the output electrical signal of the target transformer under high-frequency excitation signals of different frequencies to obtain an operating parameter curve of the target transformer; A characteristic analysis is performed based on the operating parameter curve to evaluate the winding state of the target transformer.

2. The method according to claim 1, characterized in that The electrical signal includes voltage data and current data. The input electrical signal and the output electrical signal of the target transformer under high-frequency excitation signals of different frequencies are calculated and fitted to obtain the operating parameter curve of the target transformer, specifically including: The first operating parameter values ​​corresponding to different frequencies are calculated according to the input voltage data of the primary winding and the output current data of the secondary winding of the target transformer under the high-frequency excitation signals of different frequencies, and the first operating parameter curve of the target transformer is obtained by fitting based on the first operating parameter values ​​corresponding to the different frequencies; According to the input current data of the primary winding and the output voltage data of the secondary winding of the target transformer under the high-frequency excitation signals of different frequencies, the second operating parameter values ​​corresponding to the different frequencies are calculated, and the second operating parameter curve of the target transformer is obtained by fitting based on the second operating parameter values ​​corresponding to the different frequencies; Among them, the independent variable of the operating parameter curve is ln f i , the dependent variable is In the formula, f i is the target frequency, which is any frequency within a preset frequency range, U(i) is the input voltage data or output voltage data under the high-frequency excitation signal of the target frequency, and I(i) is the input current data or output current data under the high-frequency excitation signal of the target frequency.

3. The method according to claim 2, characterized in that The performing feature analysis based on the operating parameter curve and evaluating the winding state of the target transformer specifically includes: Performing characteristic analysis based on the first operating parameter curve and the second operating parameter curve to obtain a first operating characteristic value and a second operating characteristic value; Calculate a first deformation assessment factor and a second deformation assessment factor according to the first operation characteristic value and the second operation characteristic value; A comprehensive evaluation is performed according to the first deformation assessment factor and the second deformation assessment factor to determine the winding state of the target transformer.

4. The method according to claim 3, characterized in that The calculating the first deformation assessment factor and the second deformation assessment factor according to the first operation characteristic value and the second operation characteristic value specifically includes: Performing Fourier decomposition on target input current data, target input voltage data, target output current data, and target output voltage data to obtain reference phases of the target input current data, the target input voltage data, the target output current data, and the target output voltage data, respectively, wherein the target input current data, the target input voltage data, the target output current data, and the target output voltage data are respectively input current data, input voltage data, output current data, and output voltage data under a high-frequency excitation signal of the target frequency; Calculating a current phase difference corresponding to the target frequency according to a reference phase of the target input current data and the target output current data; Calculating a voltage phase difference corresponding to the target frequency according to a reference phase of the target input voltage data and the target output voltage data; The first deformation assessment factor and the second deformation assessment factor are calculated according to the current phase difference, the voltage phase difference, the first operation characteristic value, and the second operation characteristic value.

5. The method according to claim 4, characterized in that The operation characteristic value includes an average value and a maximum value of the operation parameter value, and the first deformation assessment factor and the second deformation assessment factor are obtained by fitting and calculating the following formula: Where Ψ1 and Ψ2 are the deformation factors of the first winding and the second winding, respectively. i is the target frequency, 1≤i≤N, N is the total number of frequency values, Y 1max is the maximum value of all first run parameter values, is the voltage phase difference corresponding to the target frequency, is the current phase difference corresponding to the target frequency, Y 1(i) is the first operating parameter value at the target frequency, Y 1av is the average of all first run parameter values, Y 2max is the maximum value of all second frequency response values, Y 2(i) is the second operating parameter value at the target frequency, Y 2av is the average of all second run parameter values.

6. The method according to claim 3, characterized in that Signal injection methods include voltage transformer injection, capacitance sensor injection and station transformer injection; The step of performing a comprehensive evaluation according to the first deformation evaluation factor and the second deformation evaluation factor to determine the winding state of the target transformer specifically includes: Calculate the comprehensive evaluation coefficient according to the first deformation evaluation factor and the second deformation evaluation factor under three signal injection modes of voltage transformer, capacitance sensor and station transformer; A winding state of the target transformer is determined based on the comprehensive evaluation coefficient.

7. The method according to claim 6, characterized in that The comprehensive evaluation coefficient is calculated by the following formula: In the formula, Ψ 1(a) , 1(b) , 1(c) are the first deformation assessment factors under voltage transformer injection, capacitance sensor injection and station transformer injection, Ψ 2(a) , 2(b) , 2(c) They are the second deformation assessment factors under voltage transformer injection, capacitance sensor injection and station transformer injection respectively.

8. The method according to claim 6, characterized in that The step of determining the deformation condition of the transformer winding to be monitored based on the comprehensive evaluation coefficient specifically includes: If the comprehensive evaluation coefficient is greater than the preset coefficient threshold, the transformer winding to be monitored is in good condition; If the comprehensive evaluation coefficient is not greater than the coefficient threshold, then there is a fault in the transformer winding to be monitored.

9. A transformer winding status assessment platform, characterized in that: The platform includes a host PC, a main control board, a DC voltage source, a switch tube, a protection resistor, a coupling coil, a signal injection module, an injection current detector, an injection voltage detector, a target transformer, an output voltage detector, a capacitor, an output current detector, an equivalent impedance, and an industrial frequency power supply device; The host PC end is connected to the main control board, the main control board is connected to the switch tube, and the switch tube is connected to the DC voltage source and the coupling coil respectively; The DC voltage source is connected to the protection resistor, and the coupling coil is respectively connected to the protection resistor and the signal injection module; the signal injection module is connected to the injection current detector, the injection current detector is connected to the injection voltage detector, the injection voltage detector is connected to the target transformer, the target transformer is respectively connected to the output voltage detector, the capacitor and the equivalent resistor, the capacitor is connected to the output current detector, the equivalent resistor is connected to the industrial frequency power supply device, and the industrial frequency power supply device is connected to the host PC end.

10. The transformer winding status assessment platform according to claim 9, characterized in that: The host PC sends an evaluation command to the main control board, and the main control board controls the switch tube to continuously switch the frequency and open the switch according to the evaluation command, so that the DC voltage source outputs high-frequency excitation signals of different frequencies, and the high-frequency excitation signal flows into the coupling coil through the protection resistor, and the coupling coil couples the high-frequency excitation signal to obtain a coupled high-frequency signal, and the signal injection module injects the coupled high-frequency signal into the primary winding of the target transformer; The injection current detector and the injection voltage detector respectively collect input current data and input voltage data of the primary winding of the target transformer, the output voltage detector and the output current detector respectively collect output voltage data and output current data of the secondary winding of the target transformer, the capacitance and the equivalent impedance are peripheral electrical parameters of the target transformer, the industrial frequency power supply device calculates and fits the input voltage data, input current data, output current data and output voltage data of the target transformer under high-frequency excitation signals of different frequencies to obtain an operating parameter curve of the target transformer; based on the operating parameter curve, feature analysis is performed and the winding state of the target transformer is evaluated, and the winding state of the target transformer is sent to the host PC.

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