CN115097745A - Transformer bushing fault diagnosis system based on digital twinning and operation method - Google Patents

Abstract

The invention discloses a transformer bushing fault diagnosis system based on digital twinning and an operation method, belonging to the field of power equipment state detection. The multi-parameter online monitoring system collects and calculates relative dielectric loss, relative capacitance and partial discharge signals in the running process of the casing in real time, and transmits the collected information to the fault diagnosis software system through optical fibers for real-time display. The multi-field coupling virtual simulation model can simulate the conditions of the electric field, the temperature field and the stress distribution of the sleeve in real time and can realize bidirectional information interaction with a fault diagnosis software system. The casing failure diagnosis software system has the functions of displaying, storing, transmitting and extracting the collected casing state information in real time, and meanwhile, has a casing failure digital feature case library, and can judge whether the casing fails according to the collected information.

Description

A kind of transformer bushing fault diagnosis system and operation method based on digital twin

technical field

The invention belongs to the field of electric equipment state detection, and relates to a transformer bushing fault diagnosis system and operation method based on digital twin.

Background technique

As one of the typical oil-paper insulation equipment, capacitive high-voltage bushing is an indispensable external connection component for power transformers. It not only plays the function of leading the winding lead out of the transformer, but also bears the role of supporting and fixing the lead. The failure or damage of the high-voltage bushing will not only cause the power outage of the transformer and other related power equipment, but also often cause the bushing to explode, causing damage to the transformer and even causing a fire to further expand the scope of the accident. The safe and stable operation of the bushing directly affects the stability of the entire power grid, and the diagnosis and evaluation of its insulation state is of great significance.

At present, the insulation state diagnosis and evaluation method based on real-time monitoring data and historical monitoring data of transformer bushing shows great limitations, and its instantaneous state evaluation ability and self-adaptive state evaluation ability are poor. When the casing failure occurs rapidly or its precursor information is not obvious, the traditional threshold processing method shows one-sided evaluation under different operating conditions. At the same time, the traditional condition assessment method under the causal framework is difficult to establish a complete knowledge base due to the complex equipment mechanism and working conditions, and the maintenance cost is high and the upgrade is difficult, which hinders the optimization and improvement of the power equipment condition assessment system and further iterative update.

The emergence of digital twin technology has solved this problem very well. Digital twin refers to the use of digital technology to describe and model the characteristics, behavior, formation process and performance of physical objects, combined with multi-domain comprehensive simulation to establish a virtual model that is completely corresponding and consistent with the physical entities in the real world. Virtual-real interactive feedback, data fusion analysis, iterative decision-making optimization and other means, simulate its own behavior and performance in the real environment in real time, and make predictions about its future development trend. On the casing-based monitoring system, three-dimensional solid modeling and electric-thermal-machine multi-field coupling virtual simulation research are carried out to form a virtual model that is completely consistent with the physical entity. Digital twin is a technology that makes full use of the multi-disciplinary advantages of model, data, and intelligent integration. It has the ability to map the state of the entire life cycle of the casing. It not only provides strong analysis and decision support for the predictive maintenance of the casing, but also provides power The reasons for equipment failures are traced in detail, and the product design model in the information world is continuously improved by using the interactive feedback information, which greatly optimizes the improvement design process of the casing. Therefore, it is very important to carry out research on high-voltage casing condition diagnosis and evaluation technology based on digital twin technology. engineering practical significance.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problems in the prior art, and to provide a fault diagnosis system and operation method for transformer bushings based on digital twins, aiming to solve the problem that it is difficult to form a rich digital feature case library of bushings in the prior art for transformer bushings and Defective technical issues with high maintenance cost of case library.

To achieve the above object, the present invention adopts the following technical solutions to realize:

A digital twin-based transformer bushing fault diagnosis system proposed by the present invention includes a multi-parameter on-line monitoring system, a multi-field coupled virtual simulation model and a fault diagnosis software system; the output port of the multi-parameter on-line monitoring system and the fault diagnosis system The first input port of the diagnosis software system is connected; the output port of the multi-field coupling virtual simulation model is connected with the second input port of the fault diagnosis software system; the input port of the multi-field coupling virtual simulation model is connected to the fault The output port of the diagnostic software system is connected;

The multi-parameter on-line monitoring system is installed on the solid casing, and the multi-parameter on-line monitoring system is used to collect the relative dielectric loss, relative capacitance and partial discharge signals in real time during the operation of the casing, and transmit the collected data to the The fault diagnosis software system described above;

The multi-field coupling virtual simulation model is used to simulate the electric field, temperature field and stress distribution of the casing in real time, and change the simulation conditions in real time according to the information transmitted by the fault diagnosis software system;

The casing fault diagnosis software system is used for real-time display, storage, transmission and feature extraction of the collected casing state information, and forms a casing fault digital characteristic case database to realize the casing fault diagnosis.

Preferably, the multi-parameter online monitoring system includes a composite sensor, a collector and an industrial computer;

The composite sensor includes a first sensor installed at the oil outlet of the casing and a second sensor installed at the end screen of the casing; both the collector and the industrial computer are installed in the control cabinet;

An electrical connection is adopted between the collector and the composite sensor; the collector converts the collected signal data into a digital signal and transmits it to the industrial computer through an optical fiber, and the industrial computer is used to transmit the data to the fault. Diagnostic software system.

Preferably, a total of six sensors and three collectors are installed on the casing, and the three collectors are triggered synchronously.

Preferably, the multi-field coupled virtual simulation model is constructed by finite element analysis software according to the real structure of the casing.

Preferably, the multi-field coupling analysis is performed on the multi-field coupling virtual simulation model by using CAE software.

Preferably, an optical fiber is used between the multi-parameter on-line monitoring system and the fault diagnosis software system to convert digital signals into optical signals for transmission.

Preferably, the relative dielectric loss and the relative capacitance are calculated by using the relative measurement method, and the relative measurement method refers to selecting one other capacitive device connected in parallel with the device under test as a reference device.

Preferably, the relative dielectric loss and relative capacitance are calculated as shown in formula (1) and formula (2):

△tanδ=tanδ ₂ -tanδ ₁ ≈tan(δ ₂ -δ ₁ )=tanα (1)

Cx/Cn=Ix/In (2)

Among them, Δtanδ is the relative dielectric loss of the bushing, δ ₁ is the phase angle of the leakage current signal, δ ₂ is the phase angle of the reference current signal, and α is the phase angle between the reference current signal and the leakage current signal; Ix is the fundamental amplitude of the leakage current signal, In is the fundamental amplitude of the reference current signal, Cx is the relative capacitance of the device under test, and Cn is the relative capacitance of the reference device.

Preferably, the fault diagnosis software system is based on the Dione development platform architecture;

The casing fault digital characteristic case library includes the digital characteristic information of the casing discharge signal, the basic information of the casing discharge spectrum and the statistical calculator information of the casing discharge spectrum.

The operation method of a digital twin-based transformer bushing fault diagnosis system proposed by the present invention includes the following steps:

The multi-parameter online monitoring system collects the relative dielectric loss, relative capacitance and partial discharge signals during the operation of the casing, and then transmits the collected operation data to the fault diagnosis software system for real-time display;

At the same time, the multi-field coupling virtual simulation model changes the simulation conditions in real time according to the information transmitted by the fault diagnosis software system, and sets the typical fault of the casing in the multi-field coupling virtual simulation model to obtain the operating data under the fault, which is used to enrich the casing digital feature case library , to realize the fault diagnosis of the casing.

Compared with the prior art, the present invention has the following beneficial effects:

The invention proposes a fault diagnosis system for transformer bushings based on digital twins. Based on the digital twin technology, the constructed digital twins run synchronously with physical entities, and generate digital feature cases of bushing faults for fault diagnosis of physical entities. The extracted characteristic parameters are compared with the case library to determine whether the casing is faulty. Compared with the traditional detection method, it is easier to obtain the fault case of the casing. The virtual digital twin of the casing constructed by the multi-field coupled virtual simulation model changes the simulation conditions in real time according to the status information of the casing operation, and obtains the simulation calculation results that can reflect the real operation of the casing. Compared with the traditional detection method The abnormal condition inside the casing can be found earlier, which is beneficial to prevent the occurrence of casing failure. The casing fault diagnosis software system stores the casing fault information, which is conducive to the tracking and backtracking of the casing fault causes, so as to provide guiding opinions for improving the casing design structure.

Further, optical fiber is used between the multi-parameter online monitoring system and the casing fault diagnosis software system to convert digital signals into optical signals for transmission. Long-distance high-precision casing state parameter information transmission.

Further, the multi-field coupling virtual simulation model is built by finite element analysis software according to the real structure of the casing, which can simulate the electric field, temperature field and stress distribution of the casing in real time, and has a graphical interactive interface, which can be used for simulation process. to change the parameters in .

The operation method of a transformer bushing fault diagnosis system based on digital twin proposed by the present invention collects information through a multi-parameter on-line monitoring system and transmits it to a fault diagnosis software system, and the fault diagnosis software system interacts with the multi-field coupling virtual simulation model. Not only can the simulation conditions be changed in real time, but also the digital characteristic case library of casing faults can be enriched. The method is simple to operate and easy to realize fault diagnosis.

Description of drawings

In order to describe the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 is a diagram of a transformer bushing fault diagnosis system based on digital twin of the present invention.

FIG. 2 is a structural diagram of the multi-parameter on-line monitoring system of the present invention.

FIG. 3 is a schematic diagram of the calculation of relative dielectric loss and relative capacitance of the present invention.

4 is a two-dimensional axisymmetric model diagram of a transformer bushing of the present invention.

Among them, 1- conductor; 2- first transformer oil; 3- upper porcelain sleeve; 4- flange; 5- lower porcelain sleeve; 6- equalizing ball; 7- second transformer oil; 8- oil paper.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inside", etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings , or the orientation or positional relationship that the product of the invention is usually placed in use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed in a specific orientation and operation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are only used to differentiate the description and should not be construed to indicate or imply relative importance.

Furthermore, the presence of the term "horizontal" does not imply that the component is required to be absolutely horizontal, but rather may be tilted slightly. For example, "horizontal" only means that its direction is more horizontal than "vertical", it does not mean that the structure must be completely horizontal, but can be slightly inclined.

In the description of the embodiments of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. It can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

Below in conjunction with accompanying drawing, the present invention is described in further detail:

A digital twin-based transformer bushing fault diagnosis system, as shown in Figure 1, includes a bushing multi-parameter online monitoring system, a multi-field coupled virtual simulation model and a fault diagnosis software system, and the output ports and faults of the multi-parameter online monitoring system. The first input port of the diagnosis software system is connected; the output port of the multi-field coupling virtual simulation model is connected with the second input port of the fault diagnosis software system; the input port of the multi-field coupling virtual simulation model is connected with the output port of the fault diagnosis software system.

The multi-parameter online monitoring system is installed on the solid casing. The multi-parameter online monitoring system can collect the relative dielectric loss, relative capacitance and partial discharge signals in real time during the operation of the casing, and transmit the collected data to the fault diagnosis software system to realize real-time show. The structure diagram of the multi-parameter on-line monitoring system is shown in Figure 2. The multi-parameter on-line monitoring system includes a composite sensor, a collector and an industrial computer. The composite sensor includes a first sensor installed at the oil outlet of the casing and a screen installed at the end of the casing. The second sensor, collector and industrial computer are all installed in the control cabinet. The collector and the composite sensor are electrically connected, which is responsible for controlling the collection of relevant data, and performing operations such as analysis, comparison, calculation, conversion, and storage; the collector converts the collected signal data into digital signals and transmits them to the industrial control through optical fibers. The industrial computer is used to transmit data to the fault diagnosis software system. A total of six sensors and three collectors are installed in three phases of each transformer. The three-phase collector adopts the method of synchronous triggering and collects the data information of the three phases at the same time.

The multi-field coupling virtual simulation model is established by the finite element analysis software according to the real structure of the casing. The multi-field coupling virtual simulation model can simulate the electric field, temperature field and stress distribution of the casing in real time. The multi-field coupling virtual simulation model can be used with fault diagnosis. The software system realizes two-way information exchange.

The casing fault diagnosis software system has the functions of real-time display, storage, transmission and feature extraction of the collected casing status information. According to the collected information, determine whether the casing is faulty. The casing digitization case library template constructed by the casing fault diagnosis software system contains the following three kinds of information: the digitized characteristic information of the casing discharge signal, the basic information of the casing discharge spectrum, and the statistical calculation sub-information of the casing discharge spectrum. The basic information of the bushing discharge spectrum includes the discharge initiation phase, discharge extinction phase, phase width, discharge repetition rate, discharge volume average, discharge volume standard deviation, phase center of gravity and other basic information related to discharge of positive and negative discharges.

Among them, optical fiber is used between the multi-parameter online monitoring system and the casing fault diagnosis software system to convert digital signals into optical signals for transmission. It has the characteristics of wide frequency band, strong anti-interference ability, low loss and no temperature drift, and is suitable for long-distance transmission. Distance and high-precision casing state parameter information transmission.

The multi-field coupling virtual simulation model can change the simulation conditions in real time according to the information transmitted by the casing fault diagnosis software system. The multi-field coupling virtual simulation model runs synchronously with the casing entity, and outputs various state parameter information of the casing to the fault diagnosis software system. . After these state parameters are extracted by the fault diagnosis system, the obtained results can enrich the digital characteristic case database of casing faults.

The relative dielectric loss and relative capacitance are calculated using the relative measurement method. The relative measurement method refers to selecting another capacitive device connected in parallel with the device under test as a reference device. The reference current signal In and the measured current signal Ix are measured respectively by the signal sampling unit connected in series on the grounding line of the end screen (or low-voltage end) of the two devices. The two current signals are filtered, amplified, sampled and other digital processing. The harmonic analysis method extracts its fundamental wave components, respectively, and calculates the phase difference and amplitude ratio, so as to obtain the relative dielectric loss difference and capacitance ratio of the tested equipment and the reference equipment. The principle is shown in Figure 3.

The calculation of relative dielectric loss and relative capacitance are shown in formula (1) and formula (2):

△tanδ=tanδ ₂ -tanδ ₁ ≈tan(δ ₂ -δ ₁ )=tanα (1)

Cx/Cn=Ix/In (2)

Among them, Δtanδ is the relative dielectric loss of the bushing, δ ₁ is the phase angle of the leakage current signal, δ ₂ is the phase angle of the reference current signal, and α is the phase angle between the reference current signal and the leakage current signal; Ix is the fundamental amplitude of the leakage current signal, In is the fundamental amplitude of the reference current signal, Cx is the relative capacitance of the device under test, and Cn is the relative capacitance of the reference device.

The acquisition and calculation of the relative dielectric loss and the acquisition and calculation of the relative capacitance during the operation of the casing consist of the following processes:

(1) Collection of reference current signal: Since most of the terminal screen (or low-voltage end) of capacitive equipment is directly grounded in the secondary terminal box on its body or inside the equipment, it is difficult to directly obtain its grounding current. The grounding of the last screen is transformed, and the high-precision through-center current transformer is inserted into the grounding lead of the last screen. The high-precision data acquisition card is used to collect the output signal of the current transformer at high speed, and the analog signal is sequentially converted into the signal acquisition module. Digital signals and optical signals are transmitted to nodes near the host through optical fibers, and finally the optical signals are converted into digital signals and transmitted to the host.

(2) Collection of casing leakage current signal: the method is the same as the collection method of reference current signal.

(3) Data acquisition and transmission: High-speed acquisition of the output signal of the current transformer using a high-precision data acquisition card, converting the analog signal into a digital signal and an optical signal in turn in the signal acquisition module, and transmitting the signal to the host near the host through the optical fiber. The node finally converts the optical signal into a digital signal and transmits it to the host. Optical fiber transmission signals have the characteristics of wide frequency band, strong anti-interference ability, low loss and no temperature drift, and are suitable for long-distance high-precision data transmission.

(4) Data analysis and processing: The host is responsible for triggering signal control, data processing and analysis. It analyzes and processes the fully digitized signal, and extracts high-precision phase, amplitude and other information through Fourier transform, so as to calculate Parameters such as relative dielectric loss factor and relative capacitance at power frequency.

The on-line measurement of the partial discharge signal of the bushing consists of four parts: the current sensor, the high-frequency pulse current sensor, the acquisition device, and the control cabinet. The current sensor monitors the ground current signal at the end of the transformer bushing in real time; when the internal discharge of the oil-filled bushing occurs, a high-frequency pulse current will be generated. The current signal and the leakage current signal at the end of the casing are sent to the acquisition device. The acquisition device collects the two current signals synchronously. The high-frequency pulse current signal is recorded, stored and calculated as a symbol of the internal discharge of the oil-filled casing. The end of the casing is screened. The leakage current signal is recorded, stored and calculated as the phase signal of the internal discharge of the oil-filled bushing. The embedded computer in the control cabinet regularly reads the information of the acquisition device through the optical fiber converter, and performs operations such as analysis, calculation, storage, and forwarding.

The multi-field coupling virtual simulation model of casing is established by finite element analysis software. As shown in Figure 4, the transformer bushing model consists of conductor 1, first transformer oil 2, upper porcelain sleeve 3, flange 4, lower porcelain sleeve 5, pressure equalizing ball 6, second transformer oil 7 and oil paper 8. According to the structural parameters of the transformer bushing, materials such as aluminum and oil are laid on each part. Among them, the outside of the upper porcelain sleeve 3 is in direct contact with the air, so an air domain entity is made to simulate the air around the outside of the upper porcelain sleeve 3; similarly, the outside of the porcelain sleeve 5 is in contact with the first transformer oil 2, and an oil domain entity needs to be made to simulate The second transformer oil 7 around the outside of the lower porcelain sleeve 5 .

After the simulation model of the transformer bushing is established, the CAE software can be used to conduct multi-field coupling analysis on the multi-field coupling virtual simulation model. The steps are as follows:

(1) CAD modeling and material specification. Use the modeling tools that come with the CAE software to build a CAD model of the object under study (such as a transformer bushing), or model it with a general modeling tool and import it into CAE; then assign the material properties required for each domain and apply the corresponding source/boundary conditions.

(2) Grid generation. Most CAE software is based on meshed algorithms such as the finite element method. Grid generation is very important in equation solving, and discretization of the computational domain can prevent the results from not converging. Generally, for complex engineering problems, the subdivision process that comes with the CAE software system cannot be used (usually not efficient), and an appropriate subdivision sequence needs to be established.

(3) Solve all regional electric field equations. According to the bushing rating, the rated voltage when the bushing is operating is applied to the conductor part of the transformer bushing. Also, ground the flange domain. At the same time, resistive heat loss is calculated and used as a source in thermal analysis.

(4) Solve the heat transfer equation for all regions. Calculate the temperature by solving the equation shown below:

where ρ, C _p and k are density, specific heat and thermal conductivity, respectively. Convective heat transfer is described in terms that include u, which is the fluid flow rate. Q is the heat source distribution, consisting mainly of resistive heating generated in the internal high voltage conductors, but also a small fraction from leakage currents flowing through imperfect insulators.

In addition to the heat sources calculated above, the boundary conditions should be specified correctly. For the heat transfer area, two convection areas need to be considered, including external natural convection from the flange to the top and the air around the outer wall of the bushing, and external convection from the flange to the bottom of the bushing and the tank at the top of the transformer.

(5) Solve the structural mechanics equations of all regions and calculate the stress distribution.

(6) Check convergence. In this step, convergence conditions should be checked. Achieving convergence can be challenging due to the low velocity of the fluid. To deal with this problem, a looser convergence criterion for parameter changes should be applied in the solver.

(7) Iterative calculation. Repeat the above steps until the convergence conditions are met. That is, the number of iterations should be high enough to achieve overall computational convergence. It should be noted that for multiphysics coupling problems, we need to choose an appropriate algorithm; usually, a direct algorithm is required, and matrix preprocessing is required.

The casing fault diagnosis software system is based on the Dione development platform architecture, which has four communication technologies: CPC, inter-page communication technology, FPC, inter-process communication protocol IPC, and cross-server remote call RPC, which can satisfy the internal state of the software system and the transformer. Parameter multi-scene, multi-channel, multi-level information interaction requirements.

The casing fault diagnosis software system integrates the status quantities of various aspects of casing operation, including leakage current value, hydrogen content value, casing temperature, partial discharge and vibration. According to the collected data, each detection module draws the change image of each state parameter of the casing, realizes the visualization of the data, facilitates the maintenance and operation and maintenance personnel to judge the running status of the casing in real time, and carries out the maintenance and repair of the casing in a planned way, which is also convenient for the maintenance and repair of the casing. After the casing fails, the cause of the failure is judged and analyzed.

The operation method of a digital twin-based transformer bushing fault diagnosis system proposed by the present invention includes the following steps:

The multi-parameter online monitoring system collects the relative dielectric loss, relative capacitance and partial discharge signals during the operation of the casing, and then transmits the collected operation data to the fault diagnosis software system for real-time display;

At the same time, the multi-field coupling virtual simulation model changes the simulation conditions in real time according to the information transmitted by the fault diagnosis software system, and sets the typical fault of the casing in the multi-field coupling virtual simulation model to obtain the operating data under the fault, which is used to enrich the casing digital feature case library , to realize the fault diagnosis of the casing.

A digital twin-based transformer bushing fault diagnosis system proposed by the invention includes a multi-parameter on-line monitoring system, a multi-field coupling virtual simulation model and a fault diagnosis software system. The multi-parameter online monitoring system installed on the casing collects the oil temperature, oil pressure, micro water, relative dielectric loss, relative capacitance, partial discharge signal of the casing and transmits it to the fault diagnosis software system. The fault diagnosis software system displays the received information in real time, stores and extracts the characteristic parameters in the information, compares it with the digital characteristic case database of casing faults, and diagnoses the casing faults. The fault diagnosis software system can also transmit the information to the multi-field coupling virtual simulation model, and modify the conditions of the simulation model in real time according to the transmitted information, so as to obtain the actual casing simulation calculation results. At the same time, the casing state parameter information generated by the simulation model can also be transmitted to the fault diagnosis software system, which can process the characteristic parameters to enrich the digital characteristic case database of casing faults.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a transformer bushing fault diagnosis system based on digital twin, is characterized in that, comprises multi-parameter on-line monitoring system, multi-field coupling virtual simulation model and fault diagnosis software system; The output port of described multi-parameter on-line monitoring system and all The first input port of the fault diagnosis software system is connected; the output port of the multi-field coupling virtual simulation model is connected with the second input port of the fault diagnosis software system; the input port of the multi-field coupling virtual simulation model is connected to the connected to the output port of the fault diagnosis software system; The multi-parameter on-line monitoring system is installed on the solid casing, and the multi-parameter on-line monitoring system is used to collect the relative dielectric loss, relative capacitance and partial discharge signals in real time during the operation of the casing, and transmit the collected data to the The fault diagnosis software system described above; The multi-field coupling virtual simulation model is used to simulate the electric field, temperature field and stress distribution of the casing in real time, and change the simulation conditions in real time according to the information transmitted by the fault diagnosis software system; The casing fault diagnosis software system is used for real-time display, storage, transmission and feature extraction of the collected casing state information, and forms a casing fault digital characteristic case database to realize the casing fault diagnosis. 2. The transformer bushing fault diagnosis system based on digital twin according to claim 1, wherein the multi-parameter online monitoring system comprises a composite sensor, a collector and an industrial computer; The composite sensor includes a first sensor installed at the oil outlet of the casing and a second sensor installed at the end screen of the casing; both the collector and the industrial computer are installed in the control cabinet; An electrical connection is adopted between the collector and the composite sensor; the collector converts the collected signal data into a digital signal and transmits it to the industrial computer through an optical fiber, and the industrial computer is used to transmit the data to the fault. Diagnostic software system. 3 . The digital twin-based transformer bushing fault diagnosis system according to claim 2 , wherein a total of six sensors and three collectors are installed on the bushing, and the three collectors are triggered synchronously. 4 . 4 . The transformer bushing fault diagnosis system based on digital twin according to claim 1 , wherein the multi-field coupling virtual simulation model is built by finite element analysis software according to the real structure of the bushing. 5 . 5 . The transformer bushing fault diagnosis system based on digital twin according to claim 1 , wherein the multi-field coupling analysis is performed on the multi-field coupling virtual simulation model by using CAE software. 6 . 6. The transformer bushing fault diagnosis system based on digital twin according to claim 1, characterized in that, between the multi-parameter online monitoring system and the fault diagnosis software system, an optical fiber is used to convert a digital signal into an optical signal to carry out the process. transmission. 7. The transformer bushing fault diagnosis system based on digital twin according to claim 1, is characterized in that, the calculation of relative dielectric loss and relative capacitance adopts relative measurement method, and relative measurement method refers to selecting one set and the equipment under test. Other capacitive devices connected in parallel serve as reference devices. 8. The transformer bushing fault diagnosis system based on digital twin according to claim 7, wherein the calculation of relative dielectric loss and relative capacitance are as shown in formula (1) and formula (2): Δtanδ=tanδ ₂ -tanδ ₁ ≈tan(δ ₂ -δ ₁ )=tanα (1) Cx/Cn=Ix/In (2) Among them, Δtanδ is the relative dielectric loss of the bushing, δ ₁ is the phase angle of the leakage current signal, δ ₂ is the phase angle of the reference current signal, α is the phase angle between the reference current signal and the leakage current signal; Ix is the fundamental wave amplitude of the leakage current signal, In is the fundamental wave amplitude of the reference current signal, Cx is the relative capacitance of the device under test, and Cn is the relative capacitance of the reference device. 9. The transformer bushing fault diagnosis system based on digital twin according to claim 1, is characterized in that, the fault diagnosis software system is based on Dione development platform architecture; The casing fault digital characteristic case library includes the digital characteristic information of the casing discharge signal, the basic information of the casing discharge spectrum and the statistical calculator information of the casing discharge spectrum. 10. The operation method of the digital twin-based transformer bushing fault diagnosis system according to any one of claims 1 to 9, characterized in that, comprising the following steps: The multi-parameter online monitoring system collects the relative dielectric loss, relative capacitance and partial discharge signals during the operation of the casing, and then transmits the collected operation data to the fault diagnosis software system for real-time display; At the same time, the multi-field coupling virtual simulation model changes the simulation conditions in real time according to the information transmitted by the fault diagnosis software system, and sets the typical fault of the casing in the multi-field coupling virtual simulation model to obtain the operating data under the fault, which is used to enrich the casing digital feature case library , to realize the fault diagnosis of the casing.

Images