Transformer operation state monitoring and fault early warning method based on state index calculation

Abstract

The application discloses a transformer operation state monitoring and fault early warning method based on state index calculation, relates to the technical field of transformer operation state monitoring, and aims to solve the problem of reduced accuracy of potential fault identification. In the transformer operation process, winding temperature is collected to calculate temperature rise trend and monitor vibration state, vibration frequency is obtained, operation stress coefficient is calculated in combination with the temperature rise trend and the vibration frequency, the electric conductivity of insulation oil in the oil circulation pipeline is detected, the state index is generated by comprehensively considering the electric conductivity and the operation stress coefficient, and the transformer operation state is classified accordingly. When the state is warning, multiple groups of different cooling powers are inputted, the monitoring time is set, the corresponding radiator outlet air temperature is collected, the power change amount and the outlet air temperature difference change amount are calculated after the cooling powers are sorted, the heat dissipation characteristics are comprehensively evaluated, and it is judged whether a fault warning signal is generated, so that early warning of potential faults of the transformer is realized, and operation safety and reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer operation state monitoring, and more particularly to a transformer operation state monitoring and fault early warning method based on state index calculation. BACKGROUND

[0002] As a key device in the power system, the safety and stability of the transformer directly affect the reliable power supply capability of the entire power grid. In the prior art, the monitoring of the operation state of the transformer mainly focuses on the detection of a single parameter, such as collecting the winding temperature to evaluate the temperature rise, or detecting the mechanical state through a vibration sensor, or judging the insulation condition by monitoring the electrical performance (such as conductivity, dielectric loss factor, etc.) of the insulating oil.

[0003] The prior art has the following disadvantages:

[0004] At present, the existing single parameter monitoring method and the alarm mechanism based on threshold value cannot comprehensively reflect the comprehensive operation state of the transformer, lacks the fusion modeling and dynamic evaluation capability of multi-source operation data, and thus reduces the accuracy of potential fault identification and increases the lag of early warning response. Therefore, the transformer operation state monitoring and fault early warning method based on state index calculation is proposed.

[0005] The above information disclosed in the background section is only intended to strengthen the understanding of the background of the present disclosure, and therefore it can include information that does not constitute the prior art known to those of ordinary skill in the art. SUMMARY

[0006] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present application provide a transformer operation state monitoring and fault early warning method based on state index calculation, which generates a state index by using the fusion modeling of the temperature rise trend, vibration frequency and insulating oil conductivity, and combines the dynamic evaluation mechanism of cooling power and heat dissipation characteristics to solve the problems raised in the above background.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical scheme, a transformer operation state monitoring and fault early warning method based on state index calculation, comprising the following steps:

[0008] Step S1: During the operation of the transformer, the winding temperature of the transformer is collected and the temperature rise trend is calculated, the vibration state of the transformer is monitored, and the vibration frequency is calculated according to the vibration state;

[0009] Step S2: The temperature rise trend is combined with the vibration frequency to calculate the operation stress coefficient, the conductivity of the insulating oil in the oil circulation pipeline is detected, the state index is generated by comprehensively considering the conductivity of the insulating oil and the operation stress coefficient, and the operation state of the transformer is classified according to the state index;

[0010] Step S3: When the running state is the alarm state, a plurality of different cooling power groups are selected to input the transformer, a monitoring time is set, and the radiator outlet temperature under each group of cooling power is collected within the monitoring time;

[0011] Step S4: The cooling power is sorted, the power change amount of adjacent cooling power and the radiator outlet temperature difference change amount are calculated, the cooling characteristics are evaluated by comprehensively considering the power change amount and the radiator outlet temperature difference change amount, and it is judged whether to generate a fault alarm signal by using the cooling characteristics.

[0012] In a preferred embodiment, in step S1, during the operation of the transformer, a preset collection period is set, and the winding temperature of the transformer is obtained by an infrared temperature sensor;

[0013] The winding temperatures of the transformer at adjacent collection moments are subtracted to obtain the winding temperature rise change value of the transformer.

[0014] The average value of the winding temperature rise change value of each transformer in the preset collection period is calculated as the temperature rise trend.

[0015] In a preferred embodiment, in step S1, the vibration state includes a vibration peak acceleration and a vibration cycle interval;

[0016] The vibration acceleration signal of the transformer is obtained by an acceleration sensor in a preset collection period;

[0017] After filtering the vibration acceleration signal, the peak value in the vibration acceleration signal is taken as the vibration peak acceleration, and the time stamp corresponding to the vibration peak acceleration is recorded;

[0018] The time stamps of adjacent same-direction vibration peak accelerations are subtracted to obtain adjacent peak time stamps, if the adjacent peak time stamps are greater than a preset time interval threshold, the adjacent peak time stamps are taken as the vibration cycle interval, otherwise, the adjacent peak time stamps are removed;

[0019] The reciprocal of the vibration cycle interval is taken as the vibration frequency.

[0020] In a preferred embodiment, in step S2, the temperature rise trend and the vibration frequency are normalized by a Max-Min normalization method;

[0021] The running stress coefficient is calculated by comprehensively considering the normalized values of the temperature rise trend and the vibration frequency;

[0022] An external capacitive coupling clamp generates an alternating excitation voltage on the outer wall of the oil circulation pipeline, and an induced current is collected;

[0023] The absolute value of the ratio of the induced current to the alternating excitation voltage is taken as the amplitude admittance;

[0024] The ratio of the amplitude admittance to the preset calibration coefficient is used as the conductivity of the insulating oil in the oil circulation pipeline.

[0025] In a preferred embodiment, in step S2, the state index is calculated by integrating the normalized value of the conductivity of the insulating oil and the operating stress coefficient;

[0026] The state index is compared with a preset state index threshold value to determine:

[0027] If the state index is less than the preset state index threshold value, the operating state of the transformer is normal;

[0028] Otherwise, the operating state of the transformer is an alarm state.

[0029] In a preferred embodiment, in step S3, when the operating state is an alarm state, a cooling response test procedure is performed:

[0030] A plurality of different cooling powers are selected from the cooling power table by the control unit and inputted;

[0031] A monitoring time is set, and the radiator outlet air temperatures under the plurality of different cooling powers are collected by the digital temperature sensor within the monitoring time.

[0032] In a preferred embodiment, in step S4, the plurality of different cooling powers are sorted in ascending order according to the numerical values and integrated into a cooling power sequence;

[0033] The absolute value of the difference between adjacent cooling powers in the cooling power sequence is taken as the power variation of the adjacent cooling powers;

[0034] According to the sorting of the cooling powers in the cooling power sequence and the radiator outlet air temperatures corresponding to the cooling powers, the radiator outlet air temperatures are integrated into a radiator outlet air temperature sequence.

[0035] In a preferred embodiment, in step S4, the absolute value of the difference between adjacent radiator outlet air temperatures in the radiator outlet air temperature sequence is taken as the radiator outlet air temperature difference variation;

[0036] The power variation of the adjacent cooling powers and the radiator outlet air temperature difference variation are standardized;

[0037] The radiator feature is calculated by integrating the standardized power variation of the cooling powers and the radiator outlet air temperature difference variation.

[0038] In a preferred embodiment, in step S4, the radiator feature is compared with a preset radiator feature threshold value to determine:

[0039] If the radiator feature is less than or equal to the preset radiator feature threshold value, a fault alarm signal is generated;

[0040] If the heat dissipation feature is greater than the preset heat dissipation feature threshold, the fault alarm signal is not generated.

[0041] Technical effects and advantages of the present application:

[0042] The present application collects winding temperature and calculates temperature rise trend during the operation of the transformer, simultaneously monitors the vibration state, calculates the vibration frequency according to the vibration state, and calculates the operation stress coefficient by comprehensively combining the temperature rise trend and the vibration frequency, detects the insulation oil conductivity in the oil circulation pipeline, generates the state index by comprehensively combining the insulation oil conductivity and the operation stress coefficient, and classifies the operation state of the transformer according to the state index; when the operation state is the alarm state, multiple groups of different cooling powers are selected to input the transformer, the monitoring time is set, the radiator outlet temperature under each group of cooling power is collected within the monitoring time, the cooling power is sorted, the power change amount and the radiator outlet temperature difference change amount of adjacent cooling powers are calculated, the heat dissipation feature is comprehensively evaluated, and whether to generate the fault alarm signal is judged by using the heat dissipation feature, so that the heat dissipation abnormality is judged in time and the alarm signal is generated, thereby realizing the early warning of potential faults of the transformer, and improving the operation safety and reliability. BRIEF DESCRIPTION OF DRAWINGS

[0043] Fig. 1 The implementation flowchart of the transformer operation state monitoring and fault early warning method based on state index calculation of the present application.

[0044] Fig. 2 The step schematic diagram of the transformer operation state monitoring and fault early warning method based on state index calculation of the present application. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0046] The application detects the winding temperature and calculates the temperature rise trend in the transformer operation process, simultaneously monitors the vibration state, calculates the vibration frequency according to the vibration state, calculates the operation stress coefficient by comprehensively combining the temperature rise trend and the vibration frequency, detects the insulation oil conductivity in the oil circulation pipeline, generates the state index by comprehensively combining the insulation oil conductivity and the operation stress coefficient, classifies the transformer operation state according to the state index, selects multiple groups of different cooling powers to input the transformer when the operation state is the alarm state, sets the monitoring time, collects the radiator outlet air temperature under each group of cooling powers in the monitoring time, sorts the cooling powers, calculates the power variation and the radiator outlet air temperature difference variation of adjacent cooling powers, comprehensively evaluates the heat dissipation characteristics, and judges whether to generate the fault alarm signal by using the heat dissipation characteristics, so as to realize the early warning of the potential fault of the transformer.

[0047] Please refer to Figs. 1-2 The transformer operation state monitoring and fault early warning method based on the state index calculation comprises the following steps:

[0048] Step S1: In the transformer operation process, the winding temperature of the transformer is collected and the temperature rise trend is calculated, and the vibration state of the transformer is monitored, and the vibration frequency is calculated according to the vibration state;

[0049] Step S2: The operation stress coefficient is calculated by comprehensively combining the temperature rise trend and the vibration frequency, the conductivity of the insulation oil in the oil circulation pipeline is detected, the state index is generated by comprehensively combining the conductivity of the insulation oil and the operation stress coefficient, and the operation state of the transformer is classified according to the state index;

[0050] Step S3: When the operation state is the alarm state, multiple groups of different cooling powers are selected to input the transformer, and the monitoring time is set, and the radiator outlet air temperature under each group of cooling powers is collected in the monitoring time;

[0051] Step S4: The cooling powers are sorted, the power variation and the radiator outlet air temperature difference variation of adjacent cooling powers are calculated, the heat dissipation characteristics are evaluated by comprehensively combining the power variation and the radiator outlet air temperature difference variation, and whether to generate the fault alarm signal is judged by using the heat dissipation characteristics.

[0052] The specific implementation is as follows:

[0053] In step S1, in the transformer operation process, a preset collection period is divided into multiple collection time points, and the winding temperature of the transformer is obtained by an infrared temperature sensor;

[0054] The winding temperature of the transformer at each adjacent collection time point is subtracted to obtain the winding temperature rise change value of the transformer;

[0055] The average value of the winding temperature rise change values of the transformer at all collection time points in the preset collection period is calculated as the temperature rise trend.

[0056] It should be noted that the preset acquisition cycle is used to collect the winding temperature of the transformer in time, and the setting of the preset acquisition cycle should consider the change frequency and data fluctuation of the winding temperature of the transformer during the operation of the transformer, so as to ensure that sufficient data amount is obtained in each cycle; the infrared temperature sensor is a non-contact temperature measuring device, which receives the infrared radiation energy emitted by the surface of an object and converts it into an electrical signal, and outputs the corresponding temperature value after calculation by the internal circuit and algorithm, which is used to obtain the winding temperature of the transformer.

[0057] The vibration state refers to the overall performance of the mechanical vibration characteristics of the mechanical structure of the transformer during operation under the action of electromagnetic force, thermal expansion force or external disturbance, including vibration peak acceleration and vibration cycle interval;

[0058] The vibration acceleration signal of the transformer is obtained by the acceleration sensor in the preset acquisition cycle, the vibration acceleration signal is filtered, the peak value in the vibration acceleration signal is taken as the vibration peak acceleration, and the time stamp corresponding to the vibration peak acceleration is recorded;

[0059] The time stamps of adjacent same-direction vibration peak accelerations are subtracted to obtain adjacent peak time stamps, if the adjacent peak time stamps are greater than a preset time interval threshold, the adjacent peak time stamps are taken as the vibration cycle interval, otherwise, the adjacent peak time stamps are rejected;

[0060] The reciprocal of the vibration cycle interval is taken as the vibration frequency.

[0061] It should be explained that the acceleration sensor is a sensor capable of measuring the acceleration and direction of an object, which is used to detect the motion state and vibration condition of the object, and can obtain the vibration acceleration signal of the transformer; adjacent same-direction vibration peak accelerations refer to the maximum acceleration values appearing in two adjacent vibration cycles and having consistent directions, which are used to obtain the vibration cycle interval corresponding to adjacent same-direction vibration peak accelerations; the preset time interval threshold is a critical time interval for distinguishing and screening the vibration cycle interval, which is set according to the minimum expected vibration cycle of the transformer under the rated power frequency, for example, the magnetostriction of the transformer core under the 50Hz power frequency and the electromagnetic force of the winding produce 100Hz fundamental frequency vibration, and the period is 10ms, the time interval threshold should be set to a value less than the fundamental period, the preset time interval threshold can be 6ms to 8ms, which is set by professionals and will not be described here.

[0062] In step S2, the temperature rise trend and the vibration frequency are normalized by the Max-Min normalization method, and the calculation formula is: 、 wherein, and is the temperature rise trend and the vibration frequency, and These are the minimum and maximum values ​​of the temperature rise trend. and These are the minimum and maximum values ​​of the vibration frequency. and These are the normalized values ​​of the temperature rise trend and the vibration frequency, respectively.

[0063] The operating stress coefficient is calculated by combining the temperature rise trend and the normalized value of the vibration frequency. The calculation formula is as follows: ,in, This is the value after normalizing the temperature rise trend. It is the value after normalizing the vibration frequency. It is the operating stress coefficient;

[0064] It should be noted that the greater the temperature rise trend and the higher the vibration frequency, the greater the transformer operating load and the greater the operating stress coefficient; conversely, the smaller the temperature rise trend and the lower the vibration frequency, the smaller the transformer operating load and the smaller the operating stress coefficient.

[0065] An AC excitation voltage is generated on the outer wall of the oil circulation pipeline by an external capacitor coupling clamp, and the induced current is collected.

[0066] The absolute value of the ratio of the collected induced current to the generated AC excitation voltage is used as the amplitude admittance.

[0067] The ratio of amplitude admittance to preset calibration coefficient is used as the conductivity of insulating oil in the oil circulation pipeline;

[0068] The conductivity of the insulating oil is normalized using the following formula: ,in, For the first The conductivity of the insulating oil at each sampling time. This is the number of data collection moments within a preset data collection period. This is the normalized value of the conductivity of the insulating oil;

[0069] It should be noted that the external capacitive coupling clamp is a device used for non-contact signal acquisition and transmission. Utilizing the capacitive coupling effect, it achieves the induction and transmission of electrical signals inside the conductor by clamping electrode plates to the outside of the conductor without directly stripping the conductor's insulation layer. It is used to generate AC excitation voltage on the outer wall of the oil circulation pipeline and to collect the induced current. The amplitude admittance is the magnitude of the admittance in an AC circuit, used to describe the circuit's conductivity to AC current. The preset calibration coefficient is a proportional coefficient used to convert the measured amplitude admittance into the actual conductivity of the insulating oil. The preset calibration coefficient is obtained by sampling and calculating insulating oil with known conductivity under the same experimental environment and acquisition equipment.

[0070] The normalized value of the conductivity of the insulating oil and the operation stress coefficient are used to calculate the state index, and the calculation formula is: wherein, is the normalized value of the conductivity of the insulating oil, is the operation stress coefficient, and is a preset weighting coefficient, is the state index.

[0071] It should be noted that the greater the conductivity of the insulating oil and the greater the operation stress coefficient, the greater the state index, the performance of the insulating oil decreases and the transformer bears higher operation stress; the smaller the conductivity of the insulating oil and the smaller the operation stress coefficient, the better the performance of the insulating oil and the smoother the operation of the transformer, the smaller the state index; the preset weighting coefficient is used to adjust the influence degree of the normalized value of the conductivity of the insulating oil and the operation stress coefficient on the state index, and is set according to the contribution degree of the conductivity of the insulating oil and the operation stress coefficient to the state index in the historical monitoring data, for example, a plurality of conductivities of the insulating oil and operation stress coefficients are obtained from the historical monitoring data, and the corresponding state indexes are labeled, and the linear correlation degree between the conductivity of the insulating oil and the operation stress coefficient and the state index is calculated by using the Pearson correlation coefficient to preset the weighting coefficient.

[0072] The state index is compared with a preset state index threshold to determine:

[0073] If the state index is less than the preset state index threshold, the operation state of the transformer is a normal state.

[0074] If the state index is greater than or equal to the preset state index threshold, the operation state of the transformer is an alarm state.

[0075] It should be explained that the preset state index threshold is an important parameter for determining whether the transformer is in an alarm state, and can be preset according to the statistical characteristics of the historical state index data of the transformer in the normal operation period, for example, when the transformer is in a normal operation state, the state indexes in a plurality of acquisition periods are continuously acquired to form a historical state index sequence; the average value and the standard deviation of the state index are obtained by analyzing the historical state index sequence, and the preset state index threshold is obtained according to the average value and several times of the standard deviation; the normal state means that the insulation performance, mechanical structure and heat dissipation capacity of the transformer are at a healthy level under the current operation condition, and no immediate intervention measures are needed; the alarm state means that the transformer may have potential risks such as overheating, overload, abnormal vibration or insulation performance decline under the current operation condition, prompting that the cooling measures need to be checked and adjusted or maintained in time to prevent further deterioration and equipment failure.

[0076] In step S3, when the running state is the alarm state, a cooling response test procedure is performed, and the specific procedure is as follows:

[0077] A plurality of different cooling powers are selected from a cooling power table by the control unit and input to the transformer;

[0078] A monitoring time is set, and the outflow temperature of the radiator under a plurality of different cooling powers is collected by the digital temperature sensor within the monitoring time.

[0079] It should be explained that the control unit is a functional unit for centralized management, decision-making, and execution of instructions of a device or system, and is used to select a plurality of different cooling powers; the cooling power table is a reference table or database for storing and managing preset cooling power parameters, and is usually read by the control unit, and is used to guide the power input selection of the transformer or the cooling system of the device; the monitoring time refers to a preset time period for collecting and recording specific parameter data during operation or testing, for example, by monitoring the thermal inertia time and the cooling response time of the transformer and the cooling system, the monitoring time is set to be greater than or equal to the thermal inertia time and the cooling response time; the digital temperature sensor is a temperature measuring device that can directly output a digital signal, and is used to collect the outflow temperature of the radiator under a plurality of different cooling powers; the outflow temperature of the radiator is the temperature of the outflow of the radiator at the time of collection, which tends to be stable and no longer changes.

[0080] In step S4, the plurality of different cooling powers are sorted in ascending order according to the numerical value and integrated into a cooling power sequence;

[0081] The absolute value of the difference between adjacent cooling powers in the cooling power sequence is taken as the power change amount of the adjacent cooling powers;

[0082] According to the sorting of the cooling powers in the cooling power sequence and the outflow temperature of the radiator corresponding to the cooling powers, the outflow temperature of the radiator is integrated into an outflow temperature sequence of the radiator;

[0083] The absolute value of the difference between adjacent outflow temperatures of the radiator in the outflow temperature sequence of the radiator is taken as the outflow temperature difference change amount of the radiator;

[0084] The power change amount of the adjacent cooling powers and the outflow temperature difference change amount of the radiator are standardized;

[0085] The cooling characteristics are calculated by comprehensively considering the power change amount of the cooling powers and the outflow temperature difference change amount of the radiator after standardization, and the calculation formula is: wherein, is the number of power change amounts of adjacent cooling powers, is the standardized outflow temperature difference change amount of the radiator, is the standardized outflow temperature difference change amount of the radiator, is the standardized outflow temperature difference change amount of the radiator, The change in cooling power after standardization. Features related to heat dissipation;

[0086] It should be noted that the greater the change in cooling power and the smaller the change in radiator outlet temperature difference, the weaker the cooling system's response to power input, the insufficient or abnormal heat dissipation capacity, and the smaller the heat dissipation characteristics. Conversely, the smaller the change in cooling power and the greater the change in radiator outlet temperature difference, the more significant the radiator's response to power adjustment, the better the heat dissipation capacity, and the greater the heat dissipation characteristics.

[0087] The heat dissipation characteristics are compared with a preset heat dissipation characteristic threshold for judgment.

[0088] If the heat dissipation characteristic is less than or equal to the preset heat dissipation characteristic threshold, a fault alarm signal will be generated.

[0089] If the heat dissipation characteristics are greater than the preset heat dissipation characteristic threshold, no fault alarm signal will be generated.

[0090] It should be explained that the standardization methods include, but are not limited to, standard linear transformation based on interval scaling, Z-Score standardization based on statistics, or normalization based on nonlinear mapping functions. The application methods of standardization will not be elaborated here. The preset heat dissipation characteristic threshold is an important parameter for determining whether to generate a fault alarm signal. By analyzing the historical heat dissipation characteristics and corresponding heat dissipation states, the critical value between normal and abnormal states is analyzed, and the critical value between normal and abnormal states is selected as the preset heat dissipation characteristic threshold. The fault alarm signal refers to the prompt or alarm information actively issued when abnormal equipment operating parameters or potential faults are detected, which is used to remind maintenance personnel or automatic control systems to take corresponding measures.

[0091] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0092] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0093] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0094] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0095] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0096] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0097] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0098] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0099] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0100] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0101] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0102] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the above specification.

Claims

1. A transformer operation state monitoring and fault early warning method based on state index calculation, characterized in that: The method comprises the following steps: Step S1: During the operation of the transformer, the winding temperature of the transformer is collected and the temperature rise trend is calculated, the vibration state of the transformer is monitored, and the vibration frequency is calculated according to the vibration state; Step S2: The temperature rise trend is combined with the vibration frequency to calculate the operating stress coefficient, the conductivity of the insulating oil in the oil circulation pipeline is detected, the state index is generated by comprehensively considering the conductivity of the insulating oil and the operating stress coefficient, and the operating state of the transformer is classified according to the state index; In step S2, the temperature rise trend and the vibration frequency are normalized by a Max-Min normalization method, and the calculation formula is: , , wherein, , is the temperature rise trend and the vibration frequency, and are the minimum value and the maximum value of the temperature rise trend, and are the minimum value and the maximum value of the vibration frequency, and are the normalized values of the temperature rise trend and the vibration frequency, respectively. The running stress coefficient is calculated by the normalized value of the temperature rise trend and the vibration frequency, and the calculation formula is: wherein, is the normalized value of the temperature rise trend, is the normalized value of the vibration frequency, is the running stress coefficient; In step S2, the conductivity of the insulating oil is normalized using the following formula: ,in, For the first The conductivity of the insulating oil at each sampling time. This is the number of data collection moments within a preset data collection period. This is the normalized value of the conductivity of the insulating oil; The normalized value of the conductivity of the comprehensive insulating oil and the operating stress coefficient are used to calculate the condition index, and the calculation formula is: wherein, is the normalized value of the conductivity of the insulating oil, is the operating stress coefficient, and is a preset weighting coefficient, is the condition index. Step S3: When the operating state is the alarm state, a plurality of different cooling powers are selected to input into the transformer, a monitoring time is set, and the radiator outlet air temperatures under each group of cooling powers are collected within the monitoring time; Step S4: The cooling powers are sorted, the power change amount of adjacent cooling powers and the radiator outlet air temperature difference change amount are calculated, the heat dissipation characteristics are evaluated by comprehensively considering the power change amount and the radiator outlet air temperature difference change amount, and it is judged whether a fault alarm signal is generated or not by using the heat dissipation characteristics.

2. The transformer operating state monitoring and fault early warning method based on state index calculation according to claim 1, characterized in that: In step S1, during the operation of the transformer, a preset collection period is set, and the winding temperature of the transformer is obtained through an infrared temperature sensor; The difference value of the winding temperatures of the transformer at adjacent collection times is taken as the winding temperature rise change value of the transformer; The average value of the winding temperature rise change values of the transformer within the preset collection period is taken as the temperature rise trend.

3. The transformer operating state monitoring and fault early warning method based on state index calculation according to claim 1, characterized in that: In step S1, the vibration state includes the vibration peak acceleration and the vibration cycle interval; The vibration acceleration signal of the transformer is obtained through an acceleration sensor within the preset collection period; After the vibration acceleration signal is filtered, the peak value in the vibration acceleration signal is taken as the vibration peak acceleration, and the time stamp corresponding to the vibration peak acceleration is recorded; The time stamps of adjacent vibration peak accelerations in the same direction are subtracted to obtain the vibration cycle interval; The reciprocal of the vibration cycle interval is taken as the vibration frequency.

4. The transformer operating state monitoring and fault early warning method based on state index calculation according to claim 1, characterized in that: In step S2, an external capacitive coupling clamp is used to generate an alternating excitation voltage on the outer wall of the oil circulation pipeline, and the induced current is collected; The absolute value of the ratio of the induced current to the alternating excitation voltage is taken as the amplitude admittance; The ratio of the amplitude admittance to the preset calibration coefficient is taken as the conductivity of the insulating oil in the oil circulation pipeline.

5. The transformer operating state monitoring and fault early warning method based on state index calculation according to claim 4, characterized in that: In step S2, the state index is compared with a preset state index threshold value to determine: If the state index is less than the preset state index threshold value, the operating state of the transformer is the normal state; Otherwise, the operating state of the transformer is the alarm state.

6. The transformer operating state monitoring and fault early warning method based on state index calculation according to claim 1, characterized in that: In step S3, when the operating state is the alarm state, the cooling response test process is performed: Selecting multiple groups of different cooling powers from the cooling power table by the control unit; Generating PWMs of the DC fans according to the multiple groups of different cooling powers, and adjusting the PWMs of the DC fans to the PWMs of the DC fans corresponding to the multiple groups of different cooling powers to realize the input cooling power of the transformer; Setting a monitoring time, and collecting the radiator outlet temperatures under the multiple groups of different cooling powers by the digital temperature sensor within the monitoring time.

7. The transformer operation state monitoring and fault early warning method based on state index calculation according to claim 1, characterized in that: In step S4, the multiple groups of different cooling powers are sorted in ascending order according to the numerical values and integrated into a cooling power sequence; The difference between adjacent cooling powers in the cooling power sequence is taken as the power change of the adjacent cooling powers; The radiator outlet temperatures are integrated into a radiator outlet temperature sequence according to the sorting of the cooling powers in the cooling power sequence and the radiator outlet temperatures corresponding to the cooling powers.

8. The transformer operation state monitoring and fault early warning method based on state index calculation according to claim 7, characterized in that: In step S4, the difference between adjacent radiator outlet temperatures in the radiator outlet temperature sequence is taken as the radiator outlet temperature difference change; The power change of the adjacent cooling powers and the radiator outlet temperature difference change are standardized; The cooling feature is calculated by comprehensively processing the power change of the adjacent cooling powers and the radiator outlet temperature difference change.

9. The transformer operation state monitoring and fault early warning method based on state index calculation according to claim 8, characterized in that: In step S4, the cooling feature is compared with a preset cooling feature threshold to determine: If the cooling feature is less than or equal to the preset cooling feature threshold, a fault alarm signal is generated; If the cooling feature is greater than the preset cooling feature threshold, no fault alarm signal is generated.

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