Transformer operation state self-diagnosis method and system

Abstract

The invention discloses a transformer operation state self-diagnosis method and system, and relates to the technical field of state diagnosis, and the method comprises the following steps: obtaining and analyzing related data in a working state according to a test condition, judging the state of a primary side circuit element according to primary side data and an RLC circuit step response time constant formula, and carrying out the self-diagnosis of the operation state of a transformer. And calculating the voltage stability according to the secondary side data, calculating the delay duration of the tap switch and the damage degree of the tap switch according to the primary side data, dividing and outputting state levels, and predicting a first fault time point according to the delay duration and a preset delay duration. By predicting the first fault time point, predictive maintenance is realized, power failure accidents caused by sudden faults are avoided, various data of the primary side and the secondary side are integrated, specific analysis of a circuit model and key parts is combined, a multi-dimensional and systematic diagnosis system is formed, and comprehensive, intelligent and refined management of the operation state of the transformer is realized.

Description

A method and system for self-diagnosing the operating status of a transformer Technical Field

[0001] This invention relates to the technical field of condition diagnosis, and in particular to a method and system for self-diagnosis of transformer operating conditions. Background Technology

[0002] In recent years, transformer operation status diagnosis technology has moved from offline testing to a stage of integrating online sensing and intelligent analysis, exhibiting three-dimensional characteristics: diversified sensing methods, intelligent diagnostic models, and predictive operation and maintenance decisions, enabling rapid response and predictability of operation diagnosis results.

[0003] Currently, Chinese invention patent CN120195538A discloses a method for online monitoring and fault diagnosis of on-load tap changers in transformers. This method obtains predicted fault probability data when the on-load tap changer switches during switching operations by inputting the operating data into a trained fault probability prediction model. It then determines whether the on-load tap changer meets preset target conditions. If the on-load tap changer meets the preset target conditions, its state is determined to be normal; if it does not meet the preset target conditions, its state is determined to be faulty. However, this related technology does not investigate the impact of component problems on the data, which is not conducive to accurate judgment of the tap changer's state and is prone to misjudgment. It also does not quantify the tap changer's state, which is not conducive to the clarity of state judgment. Furthermore, it does not establish a correlation between the relevant data of the tap changer and the circuit voltage to predict the tap changer's state, which is not conducive to the simplicity and foresight of the tap changer's state judgment and has certain limitations. Summary of the Invention

[0004] The technical problem solved by this invention is that: related technologies do not investigate the impact of component problems on data, which is not conducive to accurate judgment of the tap changer status and is prone to misjudgment; they do not quantify the tap changer status, which is not conducive to the clarity of status judgment; and they do not establish the correlation between the relevant data of the tap changer and the circuit voltage, so as to predict the tap changer status, which is not conducive to the simplicity and foresight of the tap changer status judgment, and has certain limitations.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: Firstly, a self-diagnostic method for transformer operating status, comprising the following steps: Testing the transformer according to test conditions to obtain primary-side data and secondary-side data; identifying the transformer's operating mode according to a preset test method; acquiring and analyzing relevant data under the operating state; determining the state of primary-side circuit components based on the primary-side data and the RLC circuit step response time constant formula; calculating the tap changer delay time based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence; calculating voltage stability based on the secondary-side data; calculating the tap changer damage degree based on the primary-side data; classifying and outputting the state level based on the tap changer damage degree; and predicting the first fault time point based on the delay time and a preset delay time.

[0006] As a preferred embodiment of the transformer operation status self-diagnosis method described in this invention, the transformer is represented by four operating modes, including a positive half-cycle voltage boost mode, a positive half-cycle voltage drop mode, a negative half-cycle voltage boost mode, and a negative half-cycle voltage drop mode; the primary side data includes tap changer contact pressure, tap changer current waveforms on both sides, component currents on both sides, tap changer pulse time sequence, and tap changer contact vibration amplitude; the secondary side data is represented by voltage stability.

[0007] As a preferred embodiment of the transformer operation status self-diagnosis method described in this invention, the status of primary side circuit elements is determined based on primary side data and the RLC circuit step response time constant formula, and the status of primary side elements includes normal and abnormal.

[0008] In a preferred embodiment of the transformer operation status self-diagnosis method of the present invention, when the primary side component status is normal, a first troubleshooting signal is sent, and the delay duration of the primary side is calculated based on the first troubleshooting signal. The method for calculating the delay duration includes: acquiring the status of the primary side component; when the primary side component status is normal, sending the first troubleshooting signal; when the primary side component is abnormal, acquiring the problematic component and sending a first maintenance signal; responding to the first troubleshooting signal, obtaining the actual switching time point based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence; and obtaining the delay duration of the tap changer based on the actual switching time point and the theoretical switching time point; when the primary side component is abnormal, acquiring the problematic component and sending the first maintenance signal.

[0009] In a preferred embodiment of the transformer operation status self-diagnosis method described in this invention, in response to a first investigation signal, the actual switching time point is obtained based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence; the delay time of the tap changer is obtained based on the actual switching time point and the theoretical switching time point; the voltage stability is calculated based on the secondary side data; the tap changer contact state is determined based on the voltage stability; when the tap changer contact state is unstable, a first calculation signal is sent; when the tap changer contact state is stable, a first prediction signal is sent.

[0010] In a preferred embodiment of the transformer operation status self-diagnosis method described in this invention, when a first calculation signal is sent, in response to the first calculation signal, the degree of damage to the tap changer is calculated based on the primary side data, and the status level is divided and output according to the degree of damage to the tap changer; the status level includes a first level, a second level, and a third level.

[0011] In a preferred embodiment of the transformer operation status self-diagnosis method of the present invention, when a first prediction signal is sent, in response to the first prediction signal, a first fault time point is obtained according to the delay time and the preset delay time. The first fault time point is obtained by the least squares method and the definite integral formula. The preset delay time is a constant and is expressed as the maximum allowable delay time.

[0012] In a preferred embodiment of the transformer operating state self-diagnosis method described in this invention, the expression for the step response characteristic of the transformer current at the instant of tap changer switching is: ; Where i(t) is the step response of the transformer current at time t, I∞ represents the steady-state current, that is, the current value on the primary side after the tap changer switching action has passed the time constant value, τ is the time constant, that is, the time required for the current to reach steady state after the switching action, e is the exponential value, L is the total inductance value, R is the total resistance value, and C is the total capacitance value.

[0013] As a preferred embodiment of the transformer operation status self-diagnosis method described in this invention, the following steps are taken: The delay duration is obtained; the sequence number of the delay duration is counted (the sequence number is a natural number); each coordinate point is plotted with the sequence number of the delay duration as the abscissa and the delay duration as the ordinate; the coordinate points are fitted to a smooth curve using the least squares method, and the expression of the curve is obtained; the first duration is used as the output quantity of the curve expression and substituted into the curve expression to obtain the corresponding abscissa; the sequence number of the delay duration corresponding to the abscissa is obtained; according to the definite integral formula, the first area under the curve from 1 to the sequence number of the delay duration is calculated; the product of the sequence number of the delay duration and the time sequence interval of the single tap changer pulse is calculated; the second sum of the first area, the sequence number of the delay duration, and the time sequence interval of the single tap changer pulse is calculated; and the second sum is set as the first fault time point.

[0014] Secondly, a transformer operating status self-diagnosis system includes a testing module, a calculation module, and a prediction module. The testing module tests the transformer according to test conditions, obtaining primary and secondary side data. The test conditions, based on a preset test method, identify the transformer's operating modes and acquire and analyze relevant data under operating conditions. The calculation module determines the state of primary side circuit components based on the primary side data and the RLC circuit step response time constant formula. It calculates the tap changer delay time based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence. It calculates voltage stability based on the secondary side data and the tap changer damage degree based on the primary side data, classifying and outputting the state level according to the tap changer damage degree. The prediction module predicts the first fault time point based on the delay time and a preset delay time.

[0015] The beneficial effects of this invention are as follows: By predicting the time point of the first fault, the system can detect potential faults in advance, realize predictive maintenance, and avoid power outages caused by sudden faults. It integrates various data from the primary and secondary sides, such as electrical quantities, timing, and waveforms, and combines them with circuit models and specific analyses of key components to form a multi-dimensional and systematic diagnostic system. This system can more accurately identify complex fault modes of transformers than traditional single-parameter monitoring. By integrating multi-source data, analysis, model calculation, and predictive evaluation, it achieves comprehensive, intelligent, and refined management of the transformer's operating status. Attached Figure Description

[0016] Figure 1 is a schematic diagram of the basic process of a transformer operation status self-diagnosis method provided in an embodiment of the present invention. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] Referring to Figure 1, this embodiment of the present invention provides a self-diagnostic method for transformer operating status, comprising the following steps: Testing the transformer according to test conditions to obtain primary and secondary side data; identifying the transformer's operating modes according to a preset test method; acquiring and analyzing relevant data under operating conditions; determining the state of primary side circuit components based on primary side data and the RLC circuit step response time constant formula; calculating the tap changer delay time based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence; calculating voltage stability based on secondary side data; calculating the tap changer damage degree based on primary side data; classifying and outputting the state level based on the tap changer damage degree; and predicting the first fault time point based on the delay time and a preset delay time.

[0019] More preferably, by predicting the first fault time point, the system can detect potential faults in advance, achieve predictive maintenance, and avoid power outages caused by sudden faults. It integrates various data from the primary and secondary sides, such as electrical quantities, timing, and waveforms, and combines them with circuit models and specific analyses of key components to form a multi-dimensional and systematic diagnostic system. This system can more accurately identify complex fault modes of transformers than traditional single-parameter monitoring. By integrating multi-source data, analysis, model calculation, and predictive evaluation, it achieves comprehensive, intelligent, and refined management of transformer operating status.

[0020] Primary side data includes tap changer contact pressure, tap changer current waveforms on both sides, component currents on both sides, tap changer pulse time sequence, and tap changer contact vibration amplitude. Secondary side data is represented as voltage stability.

[0021] More preferably, the transformer is represented as having four operating modes, wherein the operating modes include a positive half-cycle boost mode, a positive half-cycle buck mode, a negative half-cycle boost mode, and a negative half-cycle buck mode.

[0022] More preferably, the switching between the positive and negative half-cycles is achieved by controlling the power switching transistor to switch the current direction, and the boost or buck voltage is achieved by adjusting the coil turns ratio. Utilizing the unidirectional conductivity of the diode connected in parallel with the tap changer, when the transformer operates in the positive half-cycle, the reverse-connected diode and its corresponding tap changer are disabled, while the positively connected diode and its corresponding tap changer are enabled. When the transformer operates in the negative half-cycle, the positively connected diode and its corresponding tap changer are disabled, while the reverse-connected diode and its corresponding tap changer are enabled. Positive or reverse connection means the current flows in the same direction as or opposite to the forward current flow direction; disabled means the corresponding circuit section is ignored.

[0023] More preferably, a pull-down resistor is connected in parallel with the tap changer, so that when the tap changer is active and performs a closing or opening operation, the instantaneous current of the circuit where the tap changer is located is reduced, so that the instantaneous current of the circuit where the tap changer is located is less than the breakdown current of each component in the instantaneous current of the circuit where the tap changer is located, wherein each component in the circuit where the tap changer is located includes capacitors and inductors.

[0024] More preferably, the transformer includes a primary side and a secondary side, the primary side being the side connected to the power source and the secondary side being the side connected to the load, the primary side and the secondary side being mutually inducted through the magnetic effect of the coils.

[0025] More preferably, the tap changer is driven by a tap changer drive signal, which includes an open signal and a close signal. The tap changer drive signal represents the drive signal sent by opening or closing any tap changer, and is implemented by a preset PLC code.

[0026] More preferably, the PLC code includes a start contact, a start timer, an output value, an output timer, and a reset button. The start contact is a normally open contact. The start value of the start timer is set to a first value, and the output value of the output timer is set to a second value. The timing unit for both the start timer and the output timer is seconds. The output value includes 0 and 1. When the output value is 0, the tap changer is in the open state; when the output value is 1, the tap changer is in the closed state. When the start timer reaches the first value, the corresponding start contact is closed, and the output value is 1. When the output value is 1, a closing signal is sent, the tap changer receives the closing signal and is in the closed state, the start timer stops counting, and the output timer starts counting. When the output timer value is the second value, the reset button is triggered, the start timer is cleared, the start contact returns to a normally open contact, an open signal is sent, the tap changer receives the open signal and is in the open state. This process is repeated to open or close the tap changer. The second value is matched according to the load voltage.

[0027] More preferably, before setting the PLC code for the tap changer, the tap changer is numbered, and the tap changer number includes S. i , i∈[1,6], and i is an integer. S1 and S2 are connected to the power switch. When S1 is closed, the converter is in the positive half-cycle. When S2 is closed, the converter is in the negative half-cycle. When S1, S3, and S6 are closed, the output voltage is in phase with the input voltage, and the converter is in the positive half-cycle boost mode. When S1, S4, and S5 are closed, the converter is in the positive half-cycle buck mode. When S2, S3, and S6 are closed, the output voltage is out of phase with the input voltage, and the converter is in the negative half-cycle boost mode. When S2, S4, and S5 are closed, the output voltage is in phase with the input voltage, and the converter is in the negative half-cycle buck mode. S3 and S6 control the sliding pointer to rotate clockwise, and S4 and S5 control the sliding pointer to rotate counterclockwise.

[0028] More preferably, when the primary side is in the positive half-cycle, the output voltage of the primary side is directly induced by the coil to become the input voltage of the secondary side. When the primary side is in the negative half-cycle, the output voltage of the primary side is first converted into a positive voltage by a charge pump, and then induced by the coil to become the input voltage of the secondary side. This improves the load capacity of the coil and avoids irreversible damage to the iron core caused by excessive coil saturation.

[0029] More preferably, the method for testing the transformer according to test conditions, wherein the test conditions are expressed as a first selection result of the transformer's tap changer and a first matching result of the coil turns ratio in response to the load voltage, the method for testing the transformer includes: scanning the load QR code to obtain the load voltage; retrieving the response time database; inputting the load voltage into the response time data; matching a second value corresponding to the load voltage; the load voltage being the voltage when the load is operating normally; selecting the transformer's operating mode according to the load voltage and the power supply voltage; selecting the tap changer according to the operating mode; setting the number of the selected tap changer as the first selection result; retrieving the turns calculation formula; inputting the load voltage and the power supply voltage into the turns formula to obtain the coil turns ratio; the coil turns ratio calculation expression is N=n1 / n2=v1 / v2, where N is the coil turns ratio, n1 and n2 are the number of turns in the primary coil and the number of turns in the secondary coil, and v1 and v2 are the power supply voltage and the load voltage.

[0030] More preferably, when the primary current direction is positive and the load voltage is greater than or equal to the power supply voltage, the operating mode is identified as the positive half-cycle boost mode; when the primary current direction is positive and the load voltage is less than the power supply voltage, the operating mode is identified as the positive half-cycle buck mode; when the primary current direction is reverse and the load voltage is greater than or equal to the power supply voltage, the operating mode is identified as the negative half-cycle boost mode; and when the primary current direction is reverse and the load voltage is less than the power supply voltage, the operating mode is identified as the negative half-cycle buck mode.

[0031] More preferably, under the test conditions, the first angular velocity is set as the sliding speed of the sliding pointer controlled by the first selection result. According to the rotation direction of the sliding pointer controlled by the first selection result, the sliding pointer is slid according to the first angular velocity to obtain the test result, which is represented as time series data.

[0032] More preferably, the test results include primary side data and secondary side data. The primary side data includes tap changer contact pressure, tap changer current waveforms on both sides, component currents on both sides, tap changer pulse time sequence, and tap changer contact vibration amplitude. The secondary side data is represented as voltage stability, which is calculated by a preset algorithm. The tap changer pulse time sequence is represented as a sequence of time points when the tap changer's drive signal is a closing signal.

[0033] More preferably, the power supply voltage is regulated by the voltage pulse width, which is represented by the period of time during which the square wave pulse controlling the voltage value reaches its maximum value. The larger the voltage pulse width, the larger the power supply voltage.

[0034] Based on the primary side data and the formula for the step response time constant of the RLC circuit, the state of the primary side circuit components is determined. When the primary side component state is normal, a first check signal is sent, and the delay time of the primary side is calculated based on the first check signal. More preferably, the primary side of the transformer is equivalent to a series RLC circuit. At the instant of tap changer switching, the expression for the step response characteristic of the transformer current is: ; Where i(t) is the step response of the transformer current at time t, I∞ represents the steady-state current, that is, the current value on the primary side after the tap changer switching action has passed the time constant value, τ is the time constant, that is, the time required for the current to reach steady state after the switching action, e is the exponential value, L is the total inductance value, R is the total resistance value, and C is the total capacitance value.

[0035] More preferably, the primary-side component status includes normal and abnormal. The method for determining the primary-side circuit component status based on the primary-side data and the RLC circuit step response time constant formula includes: obtaining the time constant; detecting the current on both sides of the component within the time constant; calculating the current change rate, which is calculated by a preset algorithm; setting a third value as the change rate threshold; comparing the current change rate with the third value; when the current change rate is greater than the third value, setting the corresponding component as a problem component; when a problem component exists, setting the primary-side component status as abnormal; when the current change rate is less than or equal to the third value, jumping to the next component and repeating the comparison process; when the current change rate of each component is traversed and no current change rate is greater than the third value, setting the primary-side component status as normal.

[0036] More preferably, the method for calculating the rate of change of current includes: acquiring adjacent currents, calculating a second difference between adjacent currents, where adjacent currents represent those that are adjacent in time sequence, calculating a second ratio between the second difference and the previous current in the adjacent currents, iterating through the second differences corresponding to each group of adjacent currents, calculating the average value of the second differences, and setting the average value of the second differences as the rate of change of current.

[0037] More preferably, the status of the primary side components is acquired; when the status of the primary side components is normal, a first troubleshooting signal is sent; when the primary side components are abnormal, the problematic components are acquired, and a first maintenance signal is sent.

[0038] In response to the first investigation signal, the actual switching time point is obtained based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence. The delay time of the tap changer is then obtained based on the actual switching time point and the theoretical switching time point. More preferably, when the first investigation signal is sent, the delay time on the primary side is calculated based on the first investigation signal. The method for calculating the delay time includes obtaining the current waveforms on both sides of the tap changer and the tap changer pulse sequence, setting the first current value as the boundary current, where the boundary current represents the current value generated at the instant the tap changer closes, and the boundary throttling current is larger than the steady-state current. The two current waveforms are then extracted. In the side current waveform, extract the x-coordinate of the point where the amplitude is equal to the first current value. The x-coordinate represents the time point and is recorded as the actual switching time point. Match the tap changer pulse with the smallest time interval to the critical time point in the tap changer pulse sequence. Set the tap changer pulse with the smallest time interval to the critical time point in the tap changer pulse sequence as the theoretical switching time point. Calculate the third difference between the actual switching time point and the theoretical switching time point. Iterate through the third difference corresponding to each actual switching time point and calculate the average value of the third difference. Set the average value of the third difference as the delay duration.

[0039] The voltage stability is calculated based on the secondary side data, and the tap changer contact state is determined based on the voltage stability. When the tap changer contact state is unstable, a first calculation signal is sent; when the tap changer contact state is stable, a first prediction signal is sent. More preferably, the voltage stability calculation method includes: acquiring the voltage on the secondary side, which is the voltage induced after the primary side tap changer sliding coil is connected to the contact point, and used as the input voltage of the load; calculating the first difference between adjacent voltages, which are adjacent voltages in time sequence; calculating the first ratio of the first difference to the previous voltage among the adjacent voltages; iterating through the first ratios corresponding to each group of adjacent voltages; calculating the average value of the first ratio; and setting the average value of the first ratio as the voltage stability. The smaller the voltage stability value, the more stable the voltage on the secondary side.

[0040] More preferably, the tap changer contact state includes stable contact and unstable contact. The method for determining the tap changer contact state based on voltage stability includes setting a fourth value as a stability threshold, comparing the voltage stability with the fourth value, setting the tap changer contact state to unstable contact when the voltage stability is greater than the fourth value, and setting the tap changer contact state to stable contact when the voltage stability is less than or equal to the fourth value.

[0041] When the first calculation signal is sent, in response to the first calculation signal, the degree of damage to the tap changer is calculated based on the primary side data. The degree of damage to the tap changer is then classified and output as a status level, including a first level, a second level, and a third level. More preferably, the tap changer contact pressure, tap changer contact vibration amplitude, and delay time are obtained. The standard tap changer contact pressure and standard tap changer contact vibration amplitude are also obtained. The first delay time is set as a delay time threshold. The standard tap changer contact pressure is represented by the contact pressure at closing, calibrated at the factory for the corresponding model of tap changer. The standard tap changer contact vibration amplitude... The degree is expressed as the vibration amplitude when a brand-new, corresponding model tap changer is closed under the corresponding load voltage conditions. Calculate the second ratio of the tap changer contact pressure to the standard tap changer contact pressure, calculate the third ratio of the tap changer contact vibration amplitude to the standard tap changer contact vibration amplitude, select the reciprocal of the third ratio, calculate the fourth ratio of the delay time to the delay time threshold, select the reciprocal of the fourth ratio, and calculate the first sum of the second, third, and fourth ratios. Set the first sum as the degree of tap changer damage; the smaller the value of the first sum, the greater the degree of tap changer damage.

[0042] More preferably, the status levels include a first level, a second level, and a third level, where the first level, second level, and third level represent progressively better status of the tap changer. The method for classifying the status levels includes setting a fifth value and a sixth value as level classification thresholds, wherein the fifth value is less than the sixth value; comparing a first sum value with the level classification thresholds; setting the status level to the first level when the first sum value is less than or equal to the fifth value; setting the status level to the second level when the first sum value is greater than the fifth value and less than or equal to the sixth value; and setting the status level to the third level when the first sum value is greater than the sixth value.

[0043] When the first prediction signal is sent, in response to the first prediction signal, the first fault time point is obtained according to the delay time and the preset delay time. The first fault time point is obtained by the least squares method and the definite integral formula. The preset delay time is a constant and is expressed as the maximum allowable delay time.

[0044] More preferably, the delay duration is obtained, and the sequence number of the delay duration is counted. The sequence number of the delay duration is a natural number. The coordinate points are plotted with the sequence number of the delay duration as the abscissa and the delay duration as the ordinate. The coordinate points are fitted into a smooth curve using the least squares method, and the expression of the curve is obtained. The first duration is used as the output quantity of the curve expression and substituted into the curve expression to obtain the corresponding abscissa. The sequence number of the delay duration corresponding to the abscissa is obtained. According to the definite integral formula, the first area under the curve from 1 to the sequence number of the delay duration is calculated. The product of the sequence number of the delay duration and the time sequence interval of the single tap changer pulse is calculated. The second sum of the first area, the sequence number of the delay duration and the time sequence interval of the single tap changer pulse is calculated, and the second sum is set as the first fault time point.

[0045] More preferably, by predicting the first fault time point, the system can detect potential faults in advance, achieve predictive maintenance, and avoid power outages caused by sudden faults. It integrates various data from the primary and secondary sides, such as electrical quantities, timing, and waveforms, and combines them with circuit models and specific analyses of key components to form a multi-dimensional and systematic diagnostic system. This system can more accurately identify complex fault modes of transformers than traditional single-parameter monitoring. By integrating multi-source data, analysis, model calculation, and predictive evaluation, it achieves comprehensive, intelligent, and refined management of transformer operating status.

[0046] 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 implemented on one or more computer-usable storage media containing computer-usable program code. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. 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 instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0047] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for self-diagnosing the operating status of a transformer, characterized in that, The process includes the following steps: Testing the transformer under test conditions to obtain primary and secondary side data; identifying the transformer's operating modes according to a preset test method; acquiring and analyzing relevant data under operating conditions; determining the state of primary side circuit components based on primary side data and the RLC circuit step response time constant formula; calculating the tap changer delay time based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence; calculating voltage stability based on secondary side data; calculating the tap changer damage level based on primary side data; classifying and outputting the status level based on the tap changer damage level; and predicting the first fault time point based on the delay time and a preset delay time.

2. The transformer operating status self-diagnosis method as described in claim 1, characterized in that, The primary side data includes tap changer contact pressure, tap changer current waveforms on both sides, component currents on both sides, tap changer pulse time sequence, and tap changer contact vibration amplitude. The secondary side data is represented as voltage stability. The transformer is represented as having four operating modes, including positive half-cycle boost mode, positive half-cycle buck mode, negative half-cycle boost mode, and negative half-cycle buck mode.

3. The transformer operating status self-diagnosis method as described in claim 2, characterized in that, Based on the primary side data and the formula for the step response time constant of the RLC circuit, the state of the primary side circuit elements is determined. The state of the primary side elements includes normal and abnormal.

4. The transformer operating status self-diagnosis method as described in claim 3, characterized in that, When the primary-side component is in normal condition, a first troubleshooting signal is sent. The delay duration of the primary side is calculated based on the first troubleshooting signal. The calculation method for the delay duration includes: obtaining the status of the primary-side component; when the primary-side component is in normal condition, sending the first troubleshooting signal; when the primary-side component is abnormal, obtaining the problematic component and sending a first maintenance signal; responding to the first troubleshooting signal, obtaining the actual switching time point based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence; obtaining the delay duration of the tap changer based on the actual switching time point and the theoretical switching time point; when the primary-side component is abnormal, obtaining the problematic component and sending a first maintenance signal.

5. The transformer operating status self-diagnosis method as described in claim 4, characterized in that, In response to the first investigation signal, the actual switching time point is obtained based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence. The delay time of the tap changer is obtained based on the actual switching time point and the theoretical switching time point. The voltage stability is calculated based on the secondary side data, and the tap changer contact status is determined based on the voltage stability. When the tap changer contact status is unstable, a first calculation signal is sent; when the tap changer contact status is stable, a first prediction signal is sent.

6. The transformer operating status self-diagnosis method as described in claim 4, characterized in that, When the first calculation signal is sent, in response to the first calculation signal, the degree of damage to the tap changer is calculated based on the primary side data, and the status level is divided and output according to the degree of damage to the tap changer; the status level includes the first level, the second level, and the third level.

7. The transformer operating status self-diagnosis method as described in claim 5, characterized in that, When the first prediction signal is sent, in response to the first prediction signal, the first fault time point is obtained according to the delay time and the preset delay time. The first fault time point is obtained by the least squares method and the definite integral formula. The preset delay time is a constant and is expressed as the maximum allowable delay time.

8. The transformer operating status self-diagnosis method as described in claim 1, characterized in that, At the instant the tap changer switches, the expression for the step response characteristic of the transformer current is: ； Where i(t) is the step response of the transformer current at time t, I∞ represents the steady-state current, that is, the current value on the primary side after the tap changer switching action has passed the time constant value, τ is the time constant, that is, the time required for the current to reach steady state after the switching action, e is the exponential value, L is the total inductance value, R is the total resistance value, and C is the total capacitance value.

9. The transformer operating status self-diagnosis method as described in claim 7, characterized in that, Obtain the delay duration, count the sequence number of the delay duration (the sequence number is a natural number), plot the coordinate points with the delay duration as the x-axis and the delay duration as the y-axis, fit each coordinate point into a smooth curve using the least squares method, and obtain the expression of the curve. The first duration is used as the output of the curve expression. Substitute it into the curve expression to obtain the corresponding horizontal coordinate. Obtain the index of the delay duration corresponding to the horizontal coordinate. According to the definite integral formula, calculate the first area under the curve from 1 to the index of the delay duration. Calculate the product of the index of the delay duration and the time sequence interval of the single tap changer pulse. Calculate the second sum of the first area, the index of the delay duration and the time sequence interval of the single tap changer pulse, and set the second sum as the first fault time point.

10. A transformer operating status self-diagnosis system, the system being used to execute the transformer operating status self-diagnosis method according to claim 1, characterized in that, The system includes a testing module, a calculation module, and a prediction module. The testing module tests the transformer according to test conditions, obtaining primary and secondary side data. The test conditions, based on a preset test method, identify the transformer's operating modes and acquire and analyze relevant data under operating conditions. The calculation module determines the state of primary side circuit components based on the primary side data and the RLC circuit step response time constant formula. It calculates the tap changer delay time based on the current waveforms on both sides of the tap changer and the tap changer pulse time sequence. It calculates voltage stability based on the secondary side data and the degree of tap changer damage based on the primary side data, classifying and outputting the state level according to the degree of tap changer damage. The prediction module predicts the first fault time point based on the delay time and a preset delay time.

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