Resonance suppression protection method for outdoor three-phase integrated low-impedance voltage combination transformer

Abstract

The present application relates to the technical field of combined transformers, and particularly relates to a resonance suppression protection method and system for an outdoor three-phase integrated low-impedance voltage combined transformer. The method comprises the following steps: obtaining combined transformer data to perform three-phase interaction electric parameter-topology mapping processing and three-phase current and voltage mutual inductance impedance linkage analysis of the combined transformer, and generating three-phase current-voltage mutual inductance impedance linkage data; collecting outdoor environment detection data of the combined transformer to perform external environment electric field-magnetic field fluctuation detection of the combined transformer, and generating external environment electric field-magnetic field fluctuation data; performing resonance matching suppression impedance combination processing and three-phase current and voltage suppression compensation parameter design of the combined transformer based on the external environment electric field-magnetic field fluctuation data and the three-phase current-voltage mutual inductance impedance linkage data, and performing resonance suppression protection of the combined transformer. The present application realizes low-impedance voltage combined resonance suppression protection of the combined transformer outdoors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of combined transformers, in particular to a resonance suppression protection method and system for an outdoor three-phase integrated low-impedance voltage combined transformer. BACKGROUND

[0002] Outdoor three-phase integrated low-impedance voltage combined transformers are widely used in power transmission lines, power substations and distribution networks for sensing, converting and transmitting three-phase voltage signals to ensure stable monitoring and accurate metering of the power system. The combined transformer integrates the structure of the three-phase transformer and uses a low-impedance coupling structure to improve its anti-interference performance and response speed, and to adapt to the long-term operation requirements in complex outdoor environments. In the prior art, sensor arrays, electromagnetic coupling modeling, current and voltage data processing and compensation control techniques are usually combined to realize real-time sensing and parameter regulation of the combined transformer operating state. Due to the influence of environmental electromagnetic fluctuations, uneven structure coupling and power grid harmonic interference during the outdoor operation of the three-phase transformer, there is a lack of linkage analysis and processing between the three-phase signal interaction link, environmental electromagnetic fluctuations and impedance coupling changes, which cannot dynamically identify and accurately suppress the resonance conditions of the combined transformer, resulting in current-voltage resonance phenomenon of the transformer under certain load or frequency band, and further causing signal distortion, measurement deviation and even equipment damage. SUMMARY

[0003] Therefore, the present application provides a resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combined transformer to solve at least one of the above technical problems.

[0004] To achieve the above-mentioned purpose, a resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combined transformer includes the following steps:

[0005] Step S1: Obtain combined transformer data; perform three-phase interaction electrical parameter-topology mapping processing of the combined transformer according to the combined transformer data to generate three-phase interaction electrical parameter-topology mapping data;

[0006] Step S2: Perform three-phase current and voltage interaction impedance linkage analysis of the combined transformer according to the three-phase interaction electrical parameter-topology mapping data to generate three-phase current-voltage interaction impedance linkage data;

[0007] Step S3: Collect outdoor environment detection data of the combined transformer through a sensor; perform external environment electric field-magnetic field fluctuation detection of the combined transformer according to the outdoor environment detection data to generate external environment electric field-magnetic field fluctuation data;

[0008] Step S4: based on the external environment electric field-magnetic field fluctuation data and the three-phase current-voltage mutual inductance linkage data, the resonant matching suppression impedance combination processing of the combined mutual inductor is carried out, and resonant matching suppression impedance combination data is generated;

[0009] Step S5: according to the resonant matching suppression impedance combination data, the three-phase current voltage suppression compensation parameter design of the combined mutual inductor is carried out, three-phase current voltage suppression compensation parameter data is generated, and the resonant suppression protection is executed by transmitting the three-phase current voltage suppression compensation parameter data to the combined mutual inductor.

[0010] The beneficial effects of the present application are:

[0011] The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer proposed in the present invention comprehensively captures the operating status information of the equipment by acquiring the combination transformer data, and performs three-phase interactive electrical parameter-topology mapping processing on the combination transformer, establishing a corresponding relationship between the complex electrical parameters and the complex topological structure inside the combination transformer. This can accurately reveal the mutual influence and correlation characteristics between the three-phase electrical parameters of the combination transformer, and realize real-time and accurate monitoring of the operating status of the combination transformer. Based on the three-phase interactive electrical parameter-topology mapping data, a linkage analysis of the three-phase current and voltage mutual inductance impedance of the combination transformer is performed. The three-phase current and voltage mutual inductance impedance reflect the complex relationship of the electromagnetic coupling between the three phases inside the combination transformer. Through the linkage analysis, the dynamic change process of the voltage interaction of the three-phase circuit of the combination transformer can be accurately captured. By collecting outdoor environmental data from the combined instrument transformer (CT), sensors can comprehensively and in real time capture various parameters of the CT's environment. Based on this data, the CT's external electric and magnetic field fluctuations are detected, accurately extracting the fluctuation characteristics and changing patterns of the electric and magnetic fields, thereby assessing the impact of these fluctuations on the CT. Based on this data and the three-phase current-voltage symmetric impedance linkage data, the CT's resonant matching suppression impedance combination is processed. This allows for a comprehensive and accurate analysis of the electromagnetic interference (EMI) and internal electrical characteristic changes encountered by the CT during operation. Based on this data, the CT's resonant matching suppression impedance combination is used to design the optimal suppression impedance combination scheme based on different operating conditions and electromagnetic environments. This scheme exhibits excellent real-time and adaptive performance, enabling timely adjustment of suppression strategies as operating conditions change, ensuring stable operation of the CT under various complex operating conditions. The CT's three-phase current and voltage suppression compensation parameters are designed based on the resonant matching suppression impedance combination data, enabling refined operation of the CT's operational protection, effectively suppressing resonance and compensating for current and voltage deviations. By transmitting the three-phase current and voltage suppression compensation parameter data to the combined transformer to perform resonance suppression protection, the combined transformer can adjust its own operating status in real time according to these parameters. Through the effect of the three-phase current and voltage suppression compensation parameters, the combined transformer can adjust quickly to avoid damage to other equipment caused by resonant overvoltage.

[0012] The resonant suppression protection method of the outdoor three-phase integrated low-impedance voltage combination transformer can realize dynamic identification and accurate suppression of the resonant condition of the combination transformer through multi-dimensional linkage analysis and processing of the three-phase signal mutual inductance link, external electromagnetic environment fluctuation and impedance coupling characteristic change. The current-voltage resonance of the combination transformer under various load states or different frequency bands can be effectively avoided. By accurately identifying and compensating the coupling deviation caused by various interferences, the problems such as signal distortion, measurement error and device damage can be prevented, so that the operation stability, environmental adaptability and long-term reliability of the combination transformer are comprehensively improved, and the low-impedance voltage combination resonant suppression protection of the outdoor combination transformer is realized. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The step flowchart of the resonant suppression protection method of the outdoor three-phase integrated low-impedance voltage combination transformer is shown in the figure.

[0014] Figure 2 The detailed implementation step flowchart of step S1 in the figure is shown in the figure. Figure 1

[0015] Figure 3 The detailed implementation step flowchart of step S2 in the figure is shown in the figure. Figure 1

[0016] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0017] The technical method of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, not 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 scope of protection of the present application.

[0018] In addition, the accompanying drawings are only schematic drawings of the present application, and are not necessarily drawn to scale. The same reference signs in the drawings represent the same or similar parts, and therefore repeated description thereof will be omitted. Some block diagrams shown in the drawings are functional entities, which do not necessarily correspond to physically or logically independent entities. The functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0019] ​​It should be understood that, although the terms "first", "second" or the like can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the example embodiments, a first element can be referred to as a second element, and similarly a second element can be referred to as a first element. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0020] To achieve the above object, please refer to Figures 1 to 3 The present application provides a kind of outdoor three-phase integrated low impedance voltage combination mutual inductor resonance suppression protection method, comprising the following steps:

[0021] Step S1: obtain combination mutual inductor data;According to the three-phase interaction of combination mutual inductor data electrical parameter-topology mapping processing is carried out, generates three-phase interaction electrical parameter-topology mapping data;

[0022] Step S2: according to three-phase interaction of combination mutual inductor data electrical parameter-topology mapping data carries out three-phase current and voltage mutual inductance impedance linkage analysis, generates three-phase current-voltage mutual inductance impedance linkage data;

[0023] Step S3: through sensor acquisition combination mutual inductor outdoor environment detection data;According to outdoor environment detection data carries out the external environment electric field-magnetic field fluctuation detection of combination mutual inductor, generates external environment electric field-magnetic field fluctuation data;

[0024] Step S4: based on external environment electric field-magnetic field fluctuation data and three-phase current-voltage mutual inductance impedance linkage data carries out the resonance matching inhibition impedance combination processing of combination mutual inductor, generates resonance matching inhibition impedance combination data;

[0025] Step S5: according to resonance matching inhibition impedance combination data carries out the three-phase current voltage suppression compensation parameter design of combination mutual inductor, generates three-phase current voltage suppression compensation parameter data, by three-phase current voltage suppression compensation parameter data transmission to combination mutual inductor executes resonance suppression protection.

[0026] In the embodiment of the present application, please refer to Figure 1 As shown in the figure, it is the step flow diagram of the resonance suppression protection method of the outdoor three-phase integrated low impedance voltage combination mutual inductor, in this example, the resonance suppression protection method of the outdoor three-phase integrated low impedance voltage combination mutual inductor includes the following steps:

[0027] Step S1: obtain combination mutual inductor data;According to the three-phase interaction of combination mutual inductor data electrical parameter-topology mapping processing is carried out, generates three-phase interaction electrical parameter-topology mapping data;

[0028] In an embodiment of the present invention, the data of the combined mutual inductor is obtained by a high-precision electrical parameter acquisition device. The device includes a three-phase voltage sensor and a three-phase current sensor, which are respectively installed at the three-phase output terminals of the combined mutual inductor, and synchronously acquire the instantaneous value data of voltage and current at a sampling frequency of 1000 Hz. At the same time, the device has a built-in power calculation module, which calculates the active power, reactive power and apparent power of each phase in real time according to the instantaneous power calculation formula based on the collected voltage and current data. After the data is collected, a topological mapping algorithm is used for processing. Based on the principles of graph theory, a topological diagram of the internal circuit of the mutual inductor is constructed, and components such as windings and iron cores are abstracted as nodes, and connection relationships are abstracted as edges. For the collected three-phase electrical parameters, equations are established using the node voltage method and the loop current method to solve the voltage of each node and the branch current. For example, when it is detected that the voltage of phase A is 380V and the current is 20A, the voltage of phase B is 380V and the current is 18A, and the voltage of phase C is 380V and the current is 22A, these data are substituted into the topology equation to calculate the voltage drop and current distribution relationship between each winding, and finally generate three-phase interactive electrical parameter-topology mapping data containing the electrical parameters of each node and the topological connection relationship.

[0029] Step S2: performing three-phase current and voltage interaction impedance linkage analysis of the combined transformer according to the three-phase interaction electrical parameter-topology mapping data to generate three-phase current-voltage interaction impedance linkage data;

[0030] In the embodiment of the present invention, a complex impedance calculation method is used, and according to the amplitude and phase difference of each phase voltage and current, the formula (in is the voltage phasor, The complex impedance of each phase is calculated (where is the current phasor). During the linkage analysis, the electromagnetic coupling effect between the three phases is considered. The mutual inductance model is used to calculate the mutual impedance between the phases. Assuming the core magnetic permeability of the combined transformer is constant, the mutual inductance coefficient between the windings is pre-calculated through finite element analysis. 、 、 Taking phases A and B as an example, according to the mutual inductance voltage formula ( is the imaginary unit, is the angular frequency), combined with the voltage and current relationship of phase A itself, the simultaneous equations are solved to obtain the mutual impedance matrix between phases A and B. The three phases are calculated cyclically to generate the three-phase current-voltage mutual impedance linkage data including the three-phase self-impedance, mutual impedance and mutual impedance relationship, which is finally expressed in matrix form. .

[0031] Step S3: collecting outdoor environment detection data of the combined mutual inductor through a sensor; performing external environment electric field-magnetic field fluctuation detection of the combined mutual inductor based on the outdoor environment detection data to generate external environment electric field-magnetic field fluctuation data;

[0032] In this embodiment of the present invention, sensors are used to collect outdoor environmental data from a combined transformer. An integrated environmental monitoring unit, comprising an electric field strength sensor, a magnetic field strength sensor, a temperature and humidity sensor, and a wind speed sensor, is installed within a 2-meter radius of the combined transformer to collect environmental data at a frequency of 50 Hz. After data collection, external environmental electric and magnetic field fluctuations are detected. A fast Fourier transform (FFT) is performed on the electric and magnetic field strength data to convert the time-domain signals into frequency-domain signals, and their spectral distribution is analyzed. For example, if a fluctuation component with an amplitude of 50 kV / m and a frequency of 50 Hz is detected in the electric field strength time-domain signal at a certain moment, the FFT can be used to determine its energy distribution in the frequency domain. A threshold is set to determine whether the fluctuation is abnormal. When the electric field strength amplitude of a frequency component exceeds 80 kV / m or the magnetic field strength amplitude exceeds 80 mT, it is marked as an abnormal fluctuation. At the same time, combined with temperature, humidity, wind speed and other data, the impact of environmental factors on electric field-magnetic field fluctuations is analyzed, and finally external environmental electric field-magnetic field fluctuation data including electric field-magnetic field spectrum data at each moment, abnormal fluctuation marks and environmental correlation information are generated.

[0033] Step S4: performing resonance matching suppression impedance combination processing of the combined mutual inductor based on the external environment electric field-magnetic field fluctuation data and the three-phase current-voltage mutual inductance impedance linkage data to generate resonance matching suppression impedance combination data;

[0034] In the embodiment of the present invention, a resonant frequency prediction model is first established. According to the self-impedance and mutual impedance matrix in the three-phase current-voltage mutual impedance linkage data, combined with the capacitance parameters of the combined mutual inductor (obtained by pre-measuring the capacitance between the windings), the series resonant frequency formula is used. ( is the inductor, The system's natural resonant frequency is calculated using the capacitance (for the external electric and magnetic field fluctuation data). When an interference frequency close to the natural resonant frequency is detected in the external environmental electric and magnetic field fluctuation data, the suppression impedance combination design is initiated. Using the passive filtering principle, the parameters of the required series inductor and parallel capacitor are calculated based on the interference frequency and amplitude. For example, if a 500Hz interference frequency is detected, it is calculated that a 5mH series inductor and a 199μF parallel capacitor are required to form the filter branch. By combining different inductors and capacitors, a variety of suppression impedance schemes are formed. Simulation software (such as PSIM) is used to simulate each scheme in the time and frequency domains to evaluate the resonance suppression effect. The impedance combination with the best suppression effect is selected to generate resonance matching suppression impedance combination data that includes the inductor and capacitor parameters and connection methods.

[0035] Step S5: According to the resonance matching suppression impedance combination data, the three-phase current voltage suppression compensation parameter design of the combined transformer is performed, three-phase current voltage suppression compensation parameter data is generated, and the three-phase current voltage suppression compensation parameter data is transmitted to the combined transformer to perform resonance suppression protection.

[0036] In the embodiment of the present application, the required current voltage adjustment amount for compensation is calculated according to the selected suppression impedance combination. Taking the series reactor compensation as an example, the voltage drop on the reactor is calculated according to the inductance of the reactor is the angle of change of the sinusoidal alternating current in unit time, is the inductance of the reactor, which is used to measure the size of the electromagnetic induction capability of the reactor) and the current passing through . If a 5mH reactor is connected in series in a certain phase, the current passing through is 10A, and the frequency is 50Hz, the inductance , the voltage drop , and the voltage required for compensation in that phase is 15.7V. After calculating the current voltage compensation amount of each phase, three-phase current voltage suppression compensation parameter data is generated, including the compensation voltage amplitude, phase and compensation current amplitude, phase of each phase. These parameter data are transmitted to the built-in intelligent control unit of the combined transformer through a special communication interface (such as RS-485 bus). After receiving the data, the intelligent control unit controls the internal power electronic switching device (such as IGBT module) to adjust the turns ratio of the compensation transformer or control the inductance of the controllable reactor, so as to realize real-time suppression compensation of three-phase current voltage.

[0037] Further, step S1 includes the following steps:

[0038] Step S11: Obtain combined transformer data;

[0039] Step S12: Perform three-phase electric signal parameter analysis of the combined sensor according to the combined transformer data, and generate three-phase electric signal parameter data of the combined sensor;

[0040] Step S13: Obtain combined sensor structure data, perform combined sensor unit link analysis according to the combined sensor structure data, and generate combined sensor unit link data;

[0041] Step S14: Perform response associated combined transformer analysis of each electric signal control range based on the three-phase electric signal parameter data of the combined sensor and the combined sensor unit link data, and generate response associated combined transformer data corresponding to each electric signal control range;

[0042] ​Step S15: Based on the response associated combination transformer data corresponding to each electrical signal regulation range and the combination sensor unit link data, the three-phase interactive electrical parameter-topology mapping processing of the combination transformer is performed to generate three-phase interactive electrical parameter-topology mapping data.

[0043] As an embodiment of the present application, referring to Figure 2 , a Figure 1 detailed step flowchart of step S1 in the embodiment, step S1 in the embodiment includes the following steps:

[0044] Step S11: Obtain combination transformer data;

[0045] In the embodiment of the present application, the combination transformer data is obtained by a multi-channel data acquisition device. The device is equipped with three high-precision current transformers and three voltage transformers, which are respectively connected in series to the three-phase primary side line of the combination transformer and in parallel to the three-phase bus. The data acquisition device synchronously acquires the instantaneous values of three-phase current and voltage at a sampling frequency of 2000 Hz, records the time stamp, channel number and corresponding electrical signal amplitude for each sampling point. At the same time, the device is built-in with temperature sensors to monitor the temperature of the transformer core and winding in real time, which is packaged and stored together with the electrical signal data to form an original data file containing three-phase current, voltage and temperature parameters.

[0046] Step S12: Perform three-phase electrical signal parameter analysis of the combination sensor according to the combination transformer data to generate three-phase electrical signal parameter data of the combination sensor;

[0047] In the embodiment of the present application, the Fourier transform algorithm is used to convert the acquired three-phase current and voltage time domain signals into frequency domain signals. Taking the A-phase current signal as an example, fast Fourier transform (FFT) is performed on 1024 continuous sampling points to decompose the fundamental component, each harmonic component and its amplitude and phase. The active power , is the fundamental voltage and current amplitude, is the phase difference), the reactive power , and the total harmonic distortion rate is the n-th harmonic voltage amplitude. At the same time, the power factor is determined according to the voltage and current phase difference. When the A-phase voltage phase is 0° and the current phase is 30°, the power factor . The fundamental parameters, harmonic parameters and power parameters of the three-phase electrical signal are sorted out to obtain the three-phase electrical signal parameter data of the combination sensor.

[0048] Step S13: Obtain combination sensor structure data, perform combination sensor unit link analysis according to the combination sensor structure data to generate combination sensor unit link data;​​

[0049] In the embodiment of the present application, a three-dimensional laser scanning device is used to scan the combined mutual inductor comprehensively, and point cloud data containing structures such as windings, cores, insulating components and terminal connections are obtained. The point cloud data is converted into a three-dimensional model by reverse engineering software, and the geometric dimensions, material properties and connection relationships of each component are labeled. Based on the principle of graph theory, each component is abstracted as a node, and the physical connection relationship is abstracted as an edge, and a combined sensor unit link graph is constructed. For example, the incoming line end, outgoing line end and intermediate tap of the A-phase winding are set as nodes, the current flow direction is represented by a directed edge, the link topology structure is recorded by the connection matrix of node numbers and edges, and combined sensor unit link data containing component attributes and connection relationships are generated.

[0050] Step S14: Based on the three-phase electric signal parameter data of the combined sensor, the response associated combined mutual inductor data corresponding to each electric signal control range is generated by analyzing the response association of the combined sensor unit link data in each electric signal control range.

[0051] In the embodiment of the present application, the response association analysis is performed on the combined sensor unit link data. The mapping relationship between the electric signal control range and the link node is established, and the current control range is set to 0-500A and the voltage control range is set to 0-10kV, which are divided into multiple subintervals (such as 50A for each interval of current and 1kV for each interval of voltage). Taking the change of A-phase current from 100A to 150A as an example, the change of winding end voltage and core magnetic flux in this current change interval is calculated by using the electromagnetic induction law ( for induced electromotive force, for turns, for magnetic flux) and Ohm's law according to the parameters (such as turns ratio and resistance value) of the A-phase winding in the combined sensor unit link data. The electromagnetic response of each link node under different electric signal control intervals is simulated by the finite element analysis method, such as the mutual inductance voltage of the B-phase winding caused by the change of A-phase current. The three-phase electric signal change and link node response data corresponding to each electric signal control range are sorted, and the response associated combined mutual inductor data corresponding to each electric signal control range is generated, including the control interval, the three-phase electric signal parameter change value and the node response parameter.

[0052] Step S15: Based on the response associated combined mutual inductor data corresponding to each electric signal control range and the combined sensor unit link data, the three-phase interactive electric parameter-topology mapping data of the combined mutual inductor is generated.

[0053] In the embodiment of the present application, the combined mutual inductor data and combined sensor unit link data corresponding to the response associated combination of each electric signal regulation range are subjected to three-phase interactive electric parameter-topology mapping processing. Based on the combined sensor unit link diagram, the electric signal parameter variation in the response associated data is assigned to the corresponding link node. For example, in the A-phase current 100-150 A regulation interval, the calculated winding end voltage variation value is marked on the A-phase winding node, and the mutual inductor influence is transmitted to other phase winding nodes. Using the node analysis method, equations are established for the three-phase circuit, considering the mutual impedance between nodes (calculated by pre-acquiring mutual inductor coefficients between windings through finite element analysis) and self-impedance (calculated according to winding resistance and inductance), and the voltage and current distribution of each node in different electric signal regulation ranges are solved. The three-phase electric parameters are combined with the topology structure to generate a three-dimensional topology mapping diagram, in which the color of each node represents the electric signal amplitude, the line thickness represents the current size, and the electric parameter values of each node are labeled. Finally, three-phase interactive electric parameter-topology mapping data containing three-phase electric parameter distribution, topology connection relationship and electric signal regulation response are output, supporting rotation and scaling to view topology and electric parameter information from different angles.

[0054] Further, step S2 includes the following steps:

[0055] Step S21: performing three-phase mutual inductor current loop analysis according to the three-phase interactive electric parameter-topology mapping data to generate three-phase mutual inductor current loop data;

[0056] Step S22: performing three-phase electric field coupling distribution analysis of the combined mutual inductor according to the three-phase mutual inductor current loop data to generate three-phase electric field coupling distribution data;

[0057] Step S23: performing three-phase coupled electric field intensity deviation evaluation of the combined mutual inductor on the three-phase electric field coupling distribution data to generate three-phase coupled electric field intensity deviation data;

[0058] Step S24: performing three-phase induced voltage coupling response analysis of the combined mutual inductor on the electric field coupling distribution data based on the three-phase coupled electric field intensity deviation data to generate three-phase induced voltage coupling response data;

[0059] Step S25: performing three-phase current and voltage mutual impedance linkage analysis of the combined mutual inductor according to the three-phase mutual inductor current loop data and the three-phase induced voltage coupling response data to generate three-phase current-voltage mutual impedance linkage data.

[0060] As an embodiment of the present application, referring to Figure 3 , it is Figure 1 the detailed step flowchart of step S2 in the embodiment. In the embodiment, step S2 includes the following steps:

[0061] Step S21: Perform three-phase mutual inductance current loop analysis on the combined transformer according to the three-phase interaction electrical parameter-topology mapping data, and generate three-phase mutual inductance current loop data;

[0062] In the embodiments of the present application, Kirchhoff's current law (KCL) and Kirchhoff's voltage law (KVL) in circuit theory are used to model and analyze the three-phase circuit topology of the combined transformer. Taking a three-phase four-wire circuit topology as an example, the voltage and current values of each node in the three-phase interaction electrical parameter-topology mapping data are substituted into the corresponding equations. In the three-phase circuit of the combined transformer, for each node, according to the KCL law, the sum of the currents flowing into the node is equal to the sum of the currents flowing out of the node. For example, at a certain node, the A-phase current flowing into the node is known to be 15 A, the B-phase current flowing out of the node is 8 A, and the C-phase current is , the equation can be listed, and is calculated. For each loop, according to the KVL law, the algebraic sum of the voltages along the loop is equal to zero. By traversing all nodes and loops, combining the resistance, inductance, and other parameters of each branch in the topology structure, and using matrix equations to solve each branch current, it is assumed that the impedance matrix of the three-phase circuit is , the voltage vector is , and the current vector is . The distribution of three-phase current in each branch is solved by the equation . The flow direction, magnitude, and relationship of each branch of the calculated three-phase current in each loop are sorted out to generate three-phase mutual inductance current loop data, which is presented in the form of a circuit diagram with current annotations, clearly showing the current interaction flow path in the three-phase circuit.

[0063] Step S22: Perform three-phase electric field coupling distribution analysis on the combined transformer according to the three-phase mutual inductance current loop data, and generate three-phase electric field coupling distribution data;

[0064] In the embodiments of the present application, the finite element analysis method is used to simulate and calculate the three-phase electric field distribution of the combined transformer in combination with Maxwell's equations. First, a three-dimensional model of the physical structure of the combined transformer is established to accurately construct the geometric models of the three-phase windings, core, insulating medium, and other components, and assign appropriate material properties to each component, such as the electrical conductivity of the winding, the relative permeability of the core, and the relative permittivity of the insulating medium. The current values in the three-phase mutual inductance current loop data are loaded as boundary conditions to the windings of the model. According to Ampere's Law in Maxwell's equations is the magnetic field intensity, is the current density, is the electric displacement vector, and Gauss's Law for Electric Field ​​ The electric field intensity and potential of each unit are calculated by discretizing the model into a large number of small units. Taking the area near the A-phase winding as an example, in the calculation process, the coupling effect of the magnetic field generated by the B-phase and C-phase currents on the electric field of the A-phase is considered, and the electric field intensity and direction of each unit are obtained through iterative calculation. Finally, three-phase electric field coupling distribution data including the electric field intensity, direction and potential distribution of each point in the space around the three-phase winding are generated, which are visually displayed in the form of a three-dimensional cloud chart, and different color areas represent different electric field intensity values, and the arrow direction represents the electric field direction.

[0065] Step S23: Perform three-phase coupling electric field intensity deviation evaluation on the three-phase electric field coupling distribution data to generate three-phase coupling electric field intensity deviation data;

[0066] In the embodiment of the present application, first, the standard reference value of the three-phase coupling electric field intensity is set, which is calculated based on the design parameters of the combined transformer and the electric field distribution under the ideal operating state. For example, under the design condition, the standard electric field intensity reference value at a distance of 10 cm from the center axis of the A-phase winding is set to 500 V / m, and the reference values of the B-phase and C-phase at the corresponding positions are also set. The actual electric field intensity value of each point in the three-phase electric field coupling distribution data is compared with the standard reference value. For each measurement point, the electric field intensity deviation value is calculated, and the calculation formula is: is the actual electric field intensity value, is the standard reference value). Taking a certain point near the A-phase winding as an example, if the actual measured electric field intensity value is 530 V / m, the electric field intensity deviation value of the point is After calculating the deviation values of all measurement points in the three-phase electric field coupling distribution data, the mean, maximum and minimum values of the three-phase electric field intensity deviation are calculated. The deviation data is sorted to generate three-phase coupling electric field intensity deviation data, which includes the position coordinates of each measurement point, the actual electric field intensity value, the standard reference value, the deviation value and the deviation statistical characteristics of the three phases, and intuitively reflects the deviation of the three-phase electric field intensity from the standard value.

[0067] Step S24: Perform three-phase induced voltage coupling response analysis on the electric field coupling distribution data based on the three-phase coupling electric field intensity deviation data to generate three-phase induced voltage coupling response data;

[0068] In the embodiment of the present application, according to the principle of electromagnetic induction, the Faraday's law of electromagnetic induction is the induced electromotive force, is the number of turns of the winding, ​​The induced voltage is calculated by the magnetic flux. First, the three-phase coupling electric field intensity deviation data is combined with the electric field coupling distribution data to analyze the influence of the electric field intensity deviation on the change of the magnetic flux. Taking the A-phase winding as an example, according to the change of the magnetic field caused by the electric field intensity deviation, the change rate of the magnetic flux passing through the A-phase winding is calculated, and the number of turns of the A-phase winding is The change rate of the magnetic flux is calculated as The induced electromotive force generated by the A-phase winding is Considering the mutual coupling effect between the three phases, when the electric field intensity of the B-phase deviates, it will affect the induced voltage of the A-phase and the C-phase through the magnetic field coupling. By establishing a three-phase coupling circuit model, the induced electromotive forces of each phase are taken as voltage sources, and the impedance parameters of the windings are combined to calculate the change amount of the induced voltage between the three phases caused by the electric field coupling intensity deviation. The change amount of the three-phase induced voltage, the mutual coupling relationship and the distribution at different positions are sorted to generate three-phase induced voltage coupling response data.

[0069] Step S25: According to the three-phase mutual inductance current loop data and the three-phase induced voltage coupling response data, the three-phase current and voltage mutual inductance impedance linkage analysis of the combined mutual inductor is performed to generate three-phase current-voltage mutual inductance impedance linkage data.

[0070] In the embodiment of the present application, the calculation method of complex impedance is used, and according to the amplitude and phase relationship of the three-phase current and voltage, the self-impedance of each phase and the mutual impedance between phases are calculated by the formula is the voltage phasor, is the current phasor) Considering the mutual influence between the three phases, according to the induced voltage relationship between the phases in the three-phase induced voltage coupling response data, the mutual impedance between the phases is calculated. For example, the induced voltage generated by the B-phase current change in the A-phase is , the phase is , the A-phase current is , the phase is , and the mutual impedance between the A-phase and the B-phase is By cyclically calculating the three phases, the impedance matrix composed of the three-phase self-impedance and mutual impedance is obtained The linkage relationship between the calculated three-phase current, voltage and impedance is sorted to generate three-phase current-voltage mutual inductance impedance linkage data.

[0071] Further, step S25 includes the following steps:

[0072] Step S251: According to the three-phase mutual inductance current loop data, the three-phase current mutual inductance response analysis of the combined mutual inductor is performed to generate three-phase current mutual inductance response data;

[0073] ​In the embodiments of the present application, the node analysis method and the loop current method are used to study the current interaction in the three-phase circuit of the combined transformer. Taking the three-phase four-wire combined transformer circuit as an example, the node voltages, branch currents and circuit topology information in the three-phase mutual inductance current loop data are taken as the analysis basis. For each node, according to the Kirchhoff's current law (KCL), the sum of the currents flowing into the node is equal to the sum of the currents flowing out of the node. For each independent loop, according to the Kirchhoff's voltage law (KVL), the algebraic sum of the voltages of each segment is zero along the loop. Combined with the resistance, inductance and other parameters of each branch in the circuit, the circuit model is constructed through the matrix equation. The mutual influence between the three-phase currents is analyzed, for example, when the B-phase current changes, the induced current will be generated in the A-phase winding through mutual inductance. According to the electromagnetic induction law, the induced electromotive force generated by the change of the B-phase current in the A-phase is calculated, and then the induced current is obtained. The change of the three-phase current under different conditions, the mutual influence relationship and the response characteristics of each branch current are systematically arranged, and the three-phase current mutual inductance response data containing the change curve of each phase current, the current interaction coefficient and other information are generated.

[0074] Step S252: performing three-phase voltage frequency domain analysis processing of the combined transformer according to the three-phase induced voltage coupling response data, to generate three-phase voltage frequency domain analysis data;

[0075] In the embodiments of the present application, the fast Fourier transform (FFT) algorithm is used to convert the time domain signal of the three-phase induced voltage into a frequency domain signal. Taking the A-phase induced voltage as an example, the FFT operation is performed on the time domain signal of 1024 continuous sampling points, and the time sequence voltage signal is decomposed into a sine wave superposition form of different frequency components. In the operation process, the frequency resolution of the frequency domain signal is determined as , the sampling frequency is set as 2000 Hz; , the sampling point number is set as 1024), that is, the frequency resolution is . Through the FFT operation, the amplitude and phase information of the A-phase induced voltage at different frequencies are obtained. For example, at the frequency of 50 Hz, the amplitude of the A-phase induced voltage is , and the phase is ; at the frequency of 100 Hz, the amplitude is , and the phase is . The same FFT operation is performed on the B-phase and C-phase induced voltages to obtain the amplitude and phase data of the three-phase induced voltage at each frequency. The harmonic content such as the total harmonic distortion (THD) is calculated, and the formula is , the th harmonic voltage amplitude, ​​The amplitude, phase, harmonic content and other information of the three-phase induction voltage at different frequencies are sorted to generate three-phase voltage frequency domain analysis data including a frequency axis, a voltage amplitude spectrum of each phase, a phase spectrum and a harmonic analysis result, which are presented in the form of a spectrum diagram to clearly show the frequency domain characteristics of the three-phase voltage.

[0076] Step S253: Based on the three-phase current cross-sensing response data, the three-phase voltage frequency domain analysis data is combined to extract the three-phase current and voltage coupling response frequency domain atlas of the combined mutual inductor, and three-phase current-voltage coupling response frequency domain atlas data is generated;

[0077] In the embodiment of the present application, a current-voltage coupling relationship model is established to correlate and analyze the current change in the three-phase current cross-sensing response data and the voltage frequency component in the three-phase voltage frequency domain analysis data. Taking phase A as an example, when the A-phase current changes under a certain working condition (for example, from 15A to 20A), according to the three-phase current cross-sensing response data, the change will cause corresponding changes in the A-phase current itself and the B-phase and C-phase currents. At the same time, referring to the three-phase voltage frequency domain analysis data, the amplitude and phase of the A-phase voltage under each frequency are analyzed to see how they change due to the current change. Using electromagnetic coupling theory, considering the mutual inductance and capacitive coupling effect between windings (assuming that the distributed capacitance between the A-phase and B-phase windings is ), the coupling effect of the current change on the voltage under different frequencies is calculated. At a frequency of 50Hz, the coupling effect of the A-phase current change on the A-phase voltage itself and the B-phase and C-phase voltages is calculated to be , the change in the B-phase and C-phase voltages due to the coupling of the A-phase current is , the change in the B-phase and C-phase voltages due to the coupling of the A-phase current is . The three-phase current change and the response change relationship of the three-phase voltage under each frequency are integrated by analyzing each frequency point one by one. A two-dimensional atlas drawing method is used to draw the frequency domain atlas of the nine current-voltage coupling relationships of A-A, A-B, A-C, B-A, B-B, B-C, C-A, C-B and C-C, respectively, with frequency as the horizontal axis and the three-phase voltage amplitude or phase change as the vertical axis. In the atlas, different colors and lines are used to distinguish the coupling relationship between the phases, and key frequency points and change values are labeled to generate three-phase current-voltage coupling response frequency domain atlas data containing detailed coupling response information.

[0078] Step S254: Based on the three-phase current-voltage coupling response frequency domain atlas data, the three-phase cross-sensing loop current-voltage impedance coupling characteristic data of the combined mutual inductor is analyzed to generate three-phase cross-sensing loop current-voltage impedance coupling characteristic data;

[0079] In the embodiment of the present application, the impedance calculation method in circuit theory is used to calculate the current-voltage impedance of the three-phase mutual inductance circuit at each frequency, combined with the current-voltage change relationship in the frequency domain spectrum data. For the A-phase circuit, at a certain frequency (such as 100 Hz), the known A-phase current change is , the response change of the A-phase voltage caused by the current change is , and according to the definition of impedance , is the response change of the voltage caused by the current change, is the current change), the self-impedance of the A-phase at 100 Hz is calculated as . Considering the coupling relationship between the A-phase and the B-phase, at 100 Hz, the change of the A-phase voltage caused by the B-phase current change is , the B-phase current change is , and the mutual impedance between the A-phase and the B-phase is calculated as . The self-impedance and mutual impedance of the three phases at all frequency points are calculated one by one, considering the change characteristics (such as the inductance of the inductance and the capacitance of the capacitance) of the resistance, inductance, and capacitance of the three-phase winding at different frequencies. The calculated self-impedance and mutual impedance data of the three phases at each frequency are arranged, the change trend of the impedance with the frequency is analyzed, and the mutual influence relationship of the impedance coupling between the three phases is analyzed. For example, it is observed that at certain specific frequencies, the mutual impedance between the three phases will appear peak value, resulting in enhanced current-voltage coupling. The three-phase mutual inductance circuit current-voltage impedance coupling characteristic data containing the self-impedance and mutual impedance values of the three phases at each frequency point and the impedance change trend analysis are generated.

[0080] Step S255: According to the three-phase mutual inductance circuit current-voltage impedance coupling characteristic data, the three-phase current and voltage mutual inductance impedance linkage analysis of the combined mutual inductor is performed, and the three-phase current-voltage mutual inductance impedance linkage data is generated.

[0081] In the embodiment of the present application, the self-impedance and mutual impedance values at each frequency in the three-phase mutual inductance circuit current-voltage impedance coupling characteristic data are integrated and constructed into a complete three-phase current-voltage mutual inductance impedance matrix. Assuming that at a certain operating condition, the self-impedance and mutual impedance values of the three phases at 50 Hz frequency are respectively , , , , , , , , , the constructed three-phase current-voltage mutual inductance impedance matrix is . Analyze the relationship between the elements in the matrix and the interaction between the three-phase current and voltage under different impedance conditions. When the current of phase A changes, the response changes of the voltages of phases B and C are calculated through the mutual impedance elements in the matrix, as well as the feedback effect of the changes in the currents of phases B and C on the voltage of phase A. If the current of phase A increases by 5A, the change in the voltage of phase B can be obtained according to the matrix calculation. , the voltage change of phase C is At the same time, the changes in the currents of phases B and C will react on the voltage of phase A through mutual impedance. Considering the operation of the three-phase system under different working conditions, the impedance matrix is ​​dynamically analyzed. When the system load increases, the three-phase current increases, the changes in the current and voltage of each phase are recalculated, the element values ​​of the impedance matrix are updated, and the linkage change rules of the three-phase current and voltage sympathetic impedance are observed. The dynamic linkage relationship between the three-phase current, voltage and sympathetic impedance is analyzed and summarized in detail, and the three-phase current-voltage sympathetic impedance linkage data is generated, which includes the impedance matrix, the current and voltage change calculation process and the linkage relationship analysis report, and fully reveals the sympathetic impedance linkage characteristics of the three-phase current and voltage under different working conditions.

[0082] Furthermore, step S3 includes the following steps:

[0083] Step S31: collecting outdoor environment detection data of the combined mutual inductor through a sensor, and performing outdoor electric field and magnetic field frequency domain conversion processing on the outdoor environment detection data to generate outdoor electric field-magnetic field frequency domain conversion data;

[0084] In the embodiment of the present invention, a high-precision electric field strength sensor and a magnetic field strength sensor are used, which are installed within a radius of 3 meters around the combined mutual inductor, and the time domain signals of the electric field and magnetic field are synchronously collected at a sampling frequency of 1000 Hz. At the same time, a temperature and humidity sensor, a wind speed and direction sensor, and an atmospheric pressure sensor are used to collect environmental auxiliary parameters. The time domain signals of the electric field and magnetic field are subjected to frequency domain conversion processing. The fast Fourier transform (FFT) algorithm is used to perform calculations with 1024 consecutive sampling points as a group. For example, for the electric field strength time domain signal collected at a certain moment, the sampling point sequence is , converting it into a frequency domain signal using the FFT algorithm to obtain the electric field intensity amplitude and phase information of different frequency components. The same processing is performed on the magnetic field intensity time domain signal, ultimately generating outdoor electric field-magnetic field frequency domain conversion data containing the amplitude and phase data of the electric and magnetic fields at different frequencies.

[0085] Step S32: Analyze the outdoor electric field and magnetic field strength of the combined mutual inductor according to the outdoor electric field-magnetic field frequency domain conversion data to generate outdoor electric field-magnetic field strength data;

[0086] In the embodiment of the present application, first, the electric field and magnetic field strength amplitude data of each frequency point in the frequency domain conversion data are extracted. The frequency range of interest is set to 0-1000Hz, and the electric field strength of each frequency point in this range is analyzed. Using statistical analysis method, the mean, maximum, minimum and other characteristic quantities of the electric field and magnetic field strength in different frequency bands are calculated. For example, 0-100Hz is divided into low frequency band, and the average value of the electric field strength in this band is calculated and is the number of frequency points in the low frequency band, is each frequency point). At the same time, the frequency points and their amplitudes where the electric field and magnetic field strength peaks appear are identified. Considering the spatial distribution characteristics of the electric field and magnetic field strength, since the sensor collects data at different positions around the combined transformer, the discrete measurement point data is converted into continuous spatial distribution data by spatial interpolation algorithm (such as inverse distance weighted interpolation method). A three-dimensional space grid is constructed around the combined transformer, and the estimated values of the electric field and magnetic field strength at each grid point are calculated to generate outdoor electric field-magnetic field strength data containing the electric field and magnetic field strength values of each frequency point, characteristic statistics and spatial distribution information, which is presented in the form of three-dimensional cloud chart and data table.

[0087] Step S33: analyzing the outdoor environment impact factors of the combined transformer according to the outdoor environment detection data, and generating outdoor environment impact factor data;

[0088] In the embodiment of the present application, an environmental impact factor model is established, and temperature, humidity, wind speed, wind direction, atmospheric pressure and other environmental parameters are selected as impact factors. The potential influence mechanism of each factor on the operation of the combined transformer is analyzed, such as the increase of temperature resistance of the transformer winding and the decrease of insulation performance due to the increase of humidity. For the temperature impact factor, according to the collected temperature data, the temperature change rate is calculated to analyze the influence degree of temperature change on the performance parameters of the internal materials of the transformer. For the humidity impact factor, the dielectric constant variation law of the insulating material under different humidity conditions is determined through the material characteristics manual, and then the influence of humidity on the electric field distribution of the transformer is evaluated. For the wind speed and wind direction impact factors, the mechanical vibration of the transformer caused by strong wind is considered, which affects the stability of the internal components. Using the principle of fluid mechanics, the wind force on the transformer is calculated according to the wind speed and the shape size of the transformer. The wind force is calculated by the formula ( is the air density, is the wind speed, is the drag coefficient, is the wind area). The influence degree of each environmental parameter on the combined transformer is quantified to generate outdoor environment impact factor data containing the names of each environmental impact factor, influence mechanism and quantified influence value. ​​

[0089] Step S34: Based on the outdoor environment influence factor data, the electric field-magnetic field strength data of the combined transformer is evaluated for electric field-magnetic field interference, and electric field-magnetic field interference data is generated;

[0090] In the embodiments of the present application, the environmental influence factors are correlated with the changes in electric field and magnetic field strength. For example, when the humidity increases, the dielectric constant of the insulating material changes, which can cause distortion of the electric field distribution inside the transformer, and further affect the external electric field strength. Using a weighted comprehensive evaluation method, different weight coefficients are given according to the contribution of each environmental influence factor to the electric field-magnetic field interference. Through historical data and experimental analysis, the weight of the temperature influence factor, the weight of the humidity influence factor, and the weight of the wind speed influence factor are determined. For the electric field and magnetic field strength at each frequency point, the interference degree value D after being affected by the environment is calculated, and the formula is are the interference degree sub-values caused by the temperature, humidity, and wind speed influence factors, respectively, are the influence factor weights of temperature, humidity, and wind speed, respectively). The electric field and magnetic field strength at all frequency points are evaluated for interference, and electric field-magnetic field interference data containing the electric field-magnetic field interference degree values at each frequency point and the contribution proportion of the influence factors are generated.

[0091] Step S35: According to the electric field-magnetic field interference data, the external environment electric field-magnetic field fluctuation of the combined transformer is detected, and external environment electric field-magnetic field fluctuation data is generated.

[0092] In the embodiments of the present application, a fluctuation detection threshold is set, and through statistical analysis of historical interference data, the electric field interference degree threshold is set to , and the magnetic field interference degree threshold is set to . Each frequency point in the electric field-magnetic field interference data is detected, and when the electric field interference degree value of a certain frequency point is greater than , it is judged that there is a fluctuation in the electric field at that frequency. The time, frequency, interference degree value, and related environmental influence factor state of the fluctuation are recorded. A sliding window analysis method is used, with a window of 10 minutes, to statistically analyze the number of times, duration, and frequency distribution of the electric field and magnetic field fluctuations within the window. If in a certain window, the electric field fluctuation in the 50-100Hz frequency band occurs 3 times, with a duration of 2 minutes, 1.5 minutes, and 1 minute respectively, the fluctuation characteristic information is recorded. The detected electric field-magnetic field fluctuation is sorted, and external environment electric field-magnetic field fluctuation data containing the fluctuation time, frequency, interference degree, environmental influence factor information, and fluctuation characteristic statistical quantities are generated.

[0093] ​​​​Furthermore, step S4 includes the following steps:

[0094] Step S41: Based on the external environment electric field-magnetic field fluctuation data and the three-phase current-voltage sympathetic impedance linkage data, the current and voltage frequency coupling analysis of the combined transformer is performed to generate current-voltage frequency coupling data.

[0095] In an embodiment of the present invention, Fourier transform technology is used to perform spectrum refinement analysis on the external environment electric field-magnetic field fluctuation data to extract the main fluctuation frequency points and their amplitude and phase information. Assume that at a certain moment, there is a component with a frequency of 150Hz, an amplitude of 5kV / m, and a phase of 30° in the external environment electric field fluctuation data, and there is a component with a frequency of 150Hz, an amplitude of 2mT, and a phase of 45° in the magnetic field fluctuation data. At the same time, the three-phase self-impedance and mutual impedance values ​​at a frequency of 150Hz are obtained from the three-phase current-voltage mutual impedance linkage data. For example, the self-impedance of phase A is , the mutual impedance between phases A and B is Using electromagnetic coupling theory, the effect of external electric and magnetic field fluctuations on the three-phase current and voltage of the combined transformer is calculated. According to Maxwell's equations, external electric and magnetic field fluctuations will induce electromotive force in the transformer winding, which in turn affects the current and voltage. For example, an external 150Hz magnetic field fluctuation will induce an electromotive force in the A phase winding. ( is the number of winding turns, is the magnetic flux), this electromotive force will cause the current of phase A to change . Analyze the frequency coupling relationship between the three-phase current and voltage. When the current of phase A changes due to external fluctuations, it will affect the voltage of phases B and C through mutual impedance. For example, the current of phase A changes This will cause a voltage change in phase B This frequency coupling relationship is quantified, and the coupling coefficient between the three-phase current and voltage at each frequency point is calculated. The calculated current-voltage coupling coefficient at each frequency point, the correspondence between the external fluctuation frequency and the internal current and voltage frequency, and the degree of coupling influence are organized to generate current-voltage frequency coupling data containing the frequency axis, the three-phase current-voltage coupling coefficient matrix, and the coupling influence value.

[0096] Step S42: performing equivalent load capacitance and inductance analysis of the combined transformer based on the three-phase current-voltage mutual impedance linkage data to generate equivalent load capacitance-inductance data;

[0097] In the embodiment of the present invention, the impedance value at each frequency is extracted from the three-phase current-voltage interaction impedance linkage data, and the resistance, inductance and capacitance components are separated by using the real and imaginary part decomposition method of the complex impedance. Taking phase A as an example, at a frequency of 50Hz, the self-impedance of phase A is known to be where the real part is the resistance component, and the imaginary part is the reactance component. According to the reactance formula is the inductance, is the capacitance, is the frequency), combined with the topology and known parameters of the three-phase circuit, a system of equations is established to solve the inductance and capacitance values. For example, there are inter-phase capacitances and ground capacitances in the three-phase circuit, by analyzing the mutual impedance elements in the three-phase current-voltage inductive impedance linkage data, the inter-phase coupling relationship is determined. For example, the mutual impedance between A and B phases , the imaginary part of which reflects the electromagnetic coupling between A and B phases, including the influence of mutual inductance and inter-phase capacitance. By establishing a circuit model containing self-inductance, mutual inductance, inter-phase capacitance and ground capacitance, the equivalent load capacitance and inductance values are solved by using the node voltage method and loop current method. Considering the change of impedance characteristics at different frequencies, the same analysis and calculation are carried out at multiple frequency points, and the variation curves of equivalent load capacitance and inductance with frequency are obtained.

[0098] Step S43: Based on the current-voltage frequency coupling data, the current-voltage resonance response amplitude of the combined mutual inductor is identified, and the current-voltage resonance response amplitude data is generated;

[0099] In the embodiments of the present application, the coupling coefficient in the current-voltage frequency coupling data is combined with the parameters in the equivalent load capacitance-inductance data to analyze the resonance characteristics at different frequencies. According to the circuit resonance theory, when the inductive reactance and capacitive reactance of the system are equal, i.e. is the inductance, is the capacitance, is the frequency), the circuit resonates. The inductance and capacitance values at each frequency point are extracted from the equivalent load capacitance-inductance data, and the corresponding resonance frequency is calculated. For example, for A phase, under a certain working condition, the equivalent load inductance , and the equivalent load capacitance , the resonance frequency is calculated. Combined with the current-voltage frequency coupling data, the current and voltage response amplitudes near the resonance frequency are analyzed. When the external environmental fluctuation frequency approaches the system resonance frequency, due to the frequency coupling effect, the amplitudes of current and voltage will significantly increase. For example, near the frequency of 290Hz, according to the current-voltage frequency coupling data, the coupling coefficient between the external electric field fluctuation and the A phase current is large, when there is an external electric field fluctuation of 290Hz, it will cause a large increase in the amplitude of A phase current. By calculating the current amplification factor ​​​the current amplitude at resonance, the voltage amplification factor is ( the voltage amplitude at resonance, the voltage amplitude at non-resonance). The resonance response amplitudes of the three phases at each frequency point are comprehensively analyzed to determine the resonance frequency point, the current and voltage amplitudes at resonance, and the amplification factor and other key parameters. These parameters are sorted to generate current-voltage resonance response amplitude data containing resonance frequency, three-phase current resonance response amplitude, three-phase voltage resonance response amplitude, amplification factor, and the like.

[0100] Step S44: Resonance matching and suppression impedance combination processing of the combined transformer is performed based on the equivalent load capacitance-inductance data and the current-voltage resonance response amplitude data to generate resonance matching and suppression impedance combination data.

[0101] In the embodiment of the present application, the equivalent load parameters at each frequency point are obtained from the equivalent load capacitance-inductance data, and the main resonance frequency point is determined. For example, through analysis, it is found that there is obvious resonance phenomenon near the frequency points of 50Hz, 150Hz and 290Hz. According to the current-voltage resonance response amplitude data, the amplification factor and response characteristics of the current and voltage at these resonance frequencies are understood, and the resonance frequency points that need to be focused on are determined. The impedance combination scheme is designed, and the parallel and series impedance combination is adopted to construct the resonance suppression network. For the power frequency resonance of 50Hz, a parallel capacitance-inductance resonance branch is designed to present high impedance at 50Hz and shunt the resonance current. For the high frequency resonance points (such as 150Hz and 290Hz), a series LC filter is designed to present low impedance at the resonance frequency and bypass the resonance current. The impedance combination parameters are optimized, and the capacitance and inductance values are adjusted through theoretical calculation and actual test to make the impedance combination achieve the best suppression effect at each resonance frequency.

[0102] Further, step S42 includes the following steps:

[0103] Step S421: Current mutual inductance coupling link analysis of the combined transformer is performed according to the three-phase current-voltage mutual inductance impedance linkage data to generate current mutual inductance coupling link data;

[0104] In the embodiment of the present application, the impedance matrix elements in the three-phase current-voltage mutual inductance impedance linkage data are corresponding to the actual circuit topology of the transformer. It is assumed that the impedance matrix in the three-phase current-voltage mutual inductance impedance linkage data is , wherein represents the self-impedance of phase A, Represents the mutual impedance between phase A and phase B. The current mutual inductance coupling link diagram is constructed using graph theory methods. The three-phase windings, connecting lines and related components of the mutual inductor are abstracted as nodes, and the electrical connection relationship between nodes is abstracted as edges. Taking the A-phase winding as an example, the input and output ends of the A-phase winding and the key points where there is electromagnetic coupling with other phase windings are set as nodes. The weight of the edge is determined according to the mutual impedance value. The weight reflects the strength of the current coupling between the nodes. A larger value indicates stronger current coupling between phases A and B, increasing the weight of the corresponding edge in the link diagram. Using Kirchhoff's current law (KCL) and Kirchhoff's voltage law (KVL), the nodes and loops in the current interconductance coupling link diagram are analyzed. According to the KCL law, at a given node, the sum of the currents flowing into the node equals the sum of the currents flowing out of the node. This information, including the magnitude and direction of each node current, the connectivity of each branch, the strength of current coupling, and the interaction paths between the three-phase currents, is compiled to generate current interconductance coupling link data, including node numbers, node attributes, edge connectivity, edge weights, and current data for each node. This data is presented as a visual link diagram, clearly demonstrating the specific links and characteristics of the current interconductance coupling within the combined transformer.

[0105] Step S422: performing load link voltage change detection of the combined transformer according to the current mutual inductive coupling link data to generate load link voltage change data;

[0106] In an embodiment of the present invention, high-precision voltage sensors are installed at multiple key detection points within the load link of a combined mutual inductor (CMT), such as the three-phase incoming line terminals on the load side and important branch nodes. These sensors collect voltage data at each detection point in the load link in real time at a sampling frequency of 1000 Hz. This collected voltage data is combined with current cross-coupling link data to analyze changes in the load link voltage. When the current of a particular phase changes, the currents of other phases and the load link voltage change through the current cross-coupling link. For example, if the current of phase A increases due to a load change, the mutual inductance relationship between phases A and B in the current cross-coupling link data will generate an induced electromotive force in the phase B winding, which in turn causes a change in the voltage of phase B in the load link. A differential calculation method is used to calculate the voltage change at each detection point in the load link between adjacent sampling moments. A threshold is set to determine whether the voltage change is abnormal. If the voltage change at a detection point exceeds the set threshold (e.g., 5% of the rated voltage), the moment is marked as an abnormal voltage change. The voltage value, voltage change, abnormal voltage change time and corresponding current change of each detection point at different times are sorted out to generate load link voltage change data including detection point number, timestamp, voltage value, voltage change and abnormal mark.

[0107] Step S423: Perform current-voltage frequency domain and load link capacitor response analysis of the combined transformer based on the load link voltage variation data and the current mutual inductive coupling link data, and generate current-voltage frequency domain-load link capacitor response data;

[0108] In the embodiment of the present application, the current and voltage time domain signals in the load link voltage variation data and the current mutual inductive coupling link data are converted into frequency domain by using fast Fourier transform (FFT) algorithm. Taking the A-phase load link voltage signal as an example, the FFT operation is performed on the time domain signal of 1024 continuous sampling points, which is decomposed into the superposition form of sine waves with different frequency components, so as to obtain the amplitude and phase information of the A-phase load link voltage at each frequency. The coupling relationship between the current and voltage at different frequencies is analyzed, and the mutual impedance characteristics in the current mutual inductive coupling link data are combined to determine the mutual influence degree between the three-phase current and voltage at each frequency. For example, at the frequency of 100 Hz, the influence coefficient of the B-phase current variation on the A-phase load link voltage is calculated according to the mutual impedance values of the A-phase and B-phase in the current mutual inductive coupling link data. The equivalent circuit model containing the load link capacitor is established by considering the influence of the load link capacitor on the current-voltage frequency domain response. Assuming that there are inter-phase capacitors and ground capacitors in the load link, the shunt and voltage division effects of the capacitors on the current and voltage at different frequencies are calculated according to the capacitive reactance formula of the capacitors The simulation analysis is performed by changing the capacitor value to observe the change of the current-voltage frequency domain response. The load link capacitor parameters are gradually adjusted to analyze the influence law of the capacitor variation on the current-voltage frequency domain characteristics. The current-voltage amplitude, phase, coupling relationship at each frequency, and the influence data of the capacitor variation on the frequency domain response are sorted to generate the current-voltage frequency domain-load link capacitor response data containing the frequency axis, three-phase current-voltage frequency domain parameters, and capacitor variation influence coefficient.

[0109] Step S424: Perform equivalent load capacitor and inductance analysis of the combined transformer according to the current-voltage frequency domain-load link capacitor response data, and generate equivalent load capacitor-inductance data.

[0110] In the embodiment of the present application, the current-voltage amplitude, phase, and capacitor influence coefficient information of the key frequency points are extracted from the current-voltage frequency domain-load link capacitor response data, and the impedance calculation method in the circuit theory is used to determine the equivalent load capacitor and inductance value in combination with the frequency domain characteristics. At a certain key frequency (such as 50 Hz), the A-phase load link voltage amplitude , current amplitude , and phase difference are obtained according to the current-voltage frequency domain response data, and the impedance of the A-phase at the frequency is calculated. The calculated impedance​​ Decompose into real part and , according to the reactance formula is the frequency, is the inductance, is the capacitance) to establish equations. Assuming that the reactance of phase A at 50Hz is known , the equivalent load inductance and the equivalent load capacitance are solved by simultaneous equations. If , it means that the inductive reactance is greater than the capacitive reactance, and the values of and can be calculated by gradually iterating according to combined with other known conditions (such as the relationship obtained by observing the change of frequency domain response by changing the capacitance value). The equivalent load capacitance and inductance curves with frequency are obtained by the same calculation and analysis of three-phase at multiple key frequency points (such as 50Hz, 100Hz, 150Hz, etc.).

[0111] Further, step S44 includes the following steps:

[0112] Step S441: Perform current-voltage combined resonant frequency domain analysis of the combined transformer according to the equivalent load capacitance-inductance data to generate current-voltage combined resonant frequency domain data;

[0113] In the embodiment of the present application, the three-phase equivalent load capacitance and inductance values at each frequency point are extracted from the equivalent load capacitance-inductance data, and the frequency calculation formula of series resonance and parallel resonance is used to determine the resonant frequency of the combined transformer under different operating conditions. For series resonance, the resonant frequency formula is (where is the equivalent load inductance, is the equivalent load capacitance) to calculate the series resonant frequency. Considering the coupling effect between the three phases, the mutual inductance and inter-phase capacitance parameters in the equivalent load capacitance-inductance data are analyzed to construct a three-phase coupled resonant network model. Assuming that the mutual inductance between phases A and B is , and the inter-phase capacitance is , the effects of mutual inductance and inter-phase capacitance are taken into account in the equation when calculating the combined resonant frequency. The resonant network of three-phase coupling is represented in matrix form, and the combined resonant frequency is obtained by solving the characteristic equation. The amplitude and phase response of three-phase current and voltage at each frequency are calculated by scanning different frequency points. The equivalent circuit model of the combined transformer is built using circuit simulation software (such as PSpice), the equivalent load capacitance-inductance data is input, and frequency domain scanning analysis is performed.

[0114] ​Step S442: Based on the current-voltage resonance response amplitude data, the current-voltage resonance strength and response sensitivity of the combined transformer are evaluated, and current-voltage resonance strength-sensitivity evaluation data are generated.

[0115] In the embodiment of the present application, the current-voltage amplification factor of each resonance frequency point is extracted from the current-voltage resonance response amplitude data, and the resonance strength index is defined as , wherein , and is the current-voltage amplitude at resonance, , and is the rated current-voltage value. When evaluating the resonance response sensitivity, the current-voltage amplitude change rate within ±5% of the resonance frequency point is analyzed. The sensitivity index is calculated as , wherein is the current-voltage amplitude change caused by frequency change, is the frequency change, is the resonance frequency. Combined with the phase information in the current-voltage combined resonance frequency domain data, the phase difference characteristics of three-phase current and voltage at resonance are analyzed. When resonance occurs, the phase difference between the three phases may abnormally shift, such as the phase difference between the A-phase voltage and current changing from the normal working condition of 30° to 0°. Such phase abnormal change is recorded as an auxiliary basis for resonance strength evaluation. The resonance strength, sensitivity index, phase difference data of each resonance frequency point, and evaluation criteria are sorted to generate current-voltage resonance strength-sensitivity evaluation data containing resonance frequency, resonance strength level, sensitivity level, and phase characteristics.

[0116] Step S443: According to the current-voltage resonance strength-sensitivity evaluation data, the low-impedance current-voltage combined filter analysis of the combined transformer is performed, and low-impedance current-voltage combined filter data are generated.

[0117] In the embodiment of the present application, for the frequency points with high resonance strength and high sensitivity, a low-impedance filter network is designed, and a series or parallel filter is constructed using LC filter principle. For example, for the 96Hz resonance point (resonance strength 12, sensitivity 7.5), a series LC filter is designed to present low impedance at 96Hz and bypass the resonance current. When calculating the filter parameters, according to the resonance frequency in the equivalent load capacitance-inductance data, the inductance is selected, and the capacitance is calculated. The impedance of this series filter at 96Hz is The resonant current can be effectively bypassed. Considering the three-phase coupling effect, a three-phase combined filter network is designed, LC filters are connected in series in A, B and C phases respectively, and damping resistors are connected in parallel between phases. For example, a 5mH inductor and a 55μF capacitor are connected in series in A phase, and a 100Ω damping resistor is connected in parallel between A and B phases to suppress the inter-phase resonant coupling. The combined filter network is simulated by using circuit analysis software, the resonant frequency and amplitude in the resonant strength-sensitivity evaluation data of input current and voltage are input, and the filtering effect is simulated. In the simulation, a 96Hz resonant current is injected, and the current and voltage amplitude changes before and after filtering are observed. If the current amplitude of A phase before filtering is 40A and the current amplitude after filtering is reduced to 10A, it indicates that the filtering effect is significant. Adjust the filter parameters, such as increasing the inductance to 5.5mH and reducing the capacitance to 50μF, and re-simulate until the best filtering effect is achieved.

[0118] Step S444: According to the low-impedance current and voltage combined filter data, the resonant matching and impedance combination processing of the combined transformer is performed to generate resonant matching and impedance combination data.

[0119] In the embodiment of the present application, the filter parameters and connection mode of each resonant frequency point are extracted from the low-impedance current and voltage combined filter data, and the resonant matching and impedance combination scheme is designed in combination with the actual structure of the combined transformer. For example, for the three resonant frequency points of 50Hz, 96Hz and 200Hz, corresponding LC filters are designed respectively, and the installation positions of each filter are determined (such as the primary winding outlet end, the secondary side load end, etc.). When calculating the matching parameters of impedance combination, it is ensured that the suppression impedance and the equivalent load impedance form a conjugate match at the resonant frequency point, and the power loss is maximized. For the 50Hz resonant point, the equivalent load impedance is , and the matching suppression impedance is , which can be realized by connecting a 2.5Ω resistor in series and a 1.8Ω capacitive reactance in parallel. The impedance analyzer is used to measure the actual impedance characteristics of the combined transformer after installing the suppression impedance, and the matching effect is verified. A physical implementation scheme of impedance combination is constructed, and appropriate reactors and capacitors are selected to weld or connect into a filter network according to the design parameters. In the three-phase circuit of the combined transformer, the corresponding suppression impedance combination is installed respectively, and it is ensured that the electrical connection is firm and the insulation performance meets the outdoor operation requirements. During the field test, the resonant working condition is simulated, the current and voltage signals at each resonant frequency point are injected, and the current and voltage amplitude changes of the combined transformer are monitored. If the current amplitude at the 50Hz resonant point is reduced from 30A to 5A, the current amplitude at the 96Hz resonant point is reduced from 40A to 8A, and the current amplitude at the 200Hz resonant point is reduced from 25A to 6A, it indicates that the resonant matching and suppression effect meets the standard.

[0120] Further, step S444 includes the following steps:

[0121] According to the low-impedance current-voltage combined filter data, current and voltage fluctuation correlation phase recognition of the combined transformer is performed to generate current-voltage fluctuation correlation phase data;

[0122] In the embodiment of the present application, a high-precision phase detection device is adopted, and in the three-phase circuit of the combined transformer, voltage transformers and current transformers are respectively installed at the key nodes of the primary side and the secondary side to synchronously collect the instantaneous signals of the three-phase current and voltage at a sampling frequency of 2000 Hz. After the signals are acquired, the phase locking loop (PLL) technology is used to lock the phase of the current and voltage signals at each sampling point to accurately extract the phase information of the signals. The phase difference between the current and the voltage can be accurately calculated by the PLL technology. To ensure the accuracy and comprehensiveness of the data, the phase detection device and the transformer need to be calibrated before each data collection, and it is necessary to check whether the sampling frequency is stable at 2000 Hz. At the same time, the signal quality is monitored in real time during the data collection process, and if abnormal fluctuation or distortion of the signal occurs, the fault is promptly investigated and the data is re-collected. Data is collected under different operating conditions, such as normal load, light load, heavy load, etc. The current phase, voltage phase, phase difference of the three phases at each sampling time, and the corresponding operating condition information are sorted to generate current-voltage fluctuation correlation phase data containing time stamp, three-phase current phase value, three-phase voltage phase value, and three-phase current-voltage phase difference value.

[0123] Preferably, combined current-voltage frequency domain phase shift evaluation of the combined transformer is performed according to the current-voltage fluctuation correlation phase data to generate combined current-voltage frequency domain phase shift data;

[0124] In the embodiment of the present application, the time sequence phase information in the current-voltage fluctuation correlation phase data is converted from time domain to frequency domain by using the fast Fourier transform (FFT) algorithm. Taking the A-phase current-voltage phase difference signal as an example, the phase difference time sequence of the continuous 1024 sampling points is subjected to FFT operation to obtain the phase distribution at different frequencies. The fundamental frequency (such as 50 Hz) is set as the reference frequency, and the phase shift of each frequency component relative to the fundamental frequency is calculated. Assuming that after the FFT operation, the phase of A-phase at 100 Hz frequency is , and the phase at the fundamental frequency of 50 Hz is , according to the frequency multiple relationship, the theoretical phase at 100 Hz should be , and the phase shift at 100 Hz frequency is The same phase shift calculation is performed on the three phases at multiple frequency points to analyze the variation law of the phase shift with frequency. When the combined transformer is disturbed by harmonics, the phase shift at some frequency points may abnormally increase. For example, at the frequency point of 150 Hz, the phase shift of B-phase reaches , far beyond the normal range, indicating that the phase of this frequency point is abnormally shifted.

[0125] Preferably, the current-voltage fluctuation correlation phase data is subjected to a current and voltage frequency phase stability correlation process of the combined transformer based on the combined current-voltage frequency domain phase offset data to generate current-voltage frequency phase stability correlation data;

[0126] In the embodiment of the present invention, a phase stability correlation model is established to analyze the influence of the frequency points where abnormal offset occurs in the combined current and voltage frequency domain phase offset data on the current-voltage fluctuation correlation phase data. A phase compensation algorithm is used to adjust the frequency components with large phase offset. For example, the compensation phase value is calculated based on the phase offset . In the current-voltage fluctuation associated phase data, the phase of the 200Hz frequency component of phase C is adjusted to restore its phase to a reasonable range. Digital signal processing technology is used to filter and reconstruct the current and voltage signals to eliminate signal distortion caused by phase offset. By designing a bandpass filter, the interfering frequency components that cause abnormal phase offset are filtered out, and then the signal is phase corrected and the amplitude is adjusted to make the phase relationship between the current and voltage signals at each frequency point tend to be stable. During the processing process, the adjusted current-voltage fluctuation associated phase data is continuously monitored to ensure that the phase difference at each frequency point is within the allowable range.

[0127] Preferably, the low-impedance current-voltage combined filter data is subjected to a resonance matching suppression impedance combination process of the combined mutual inductor based on the current-voltage frequency-phase stability correlation data to generate resonance matching suppression impedance combination data.

[0128] In the embodiment of the present invention, the filter parameters and connection mode in the low impedance current-voltage combined filter data are optimized according to the phase relationship of each frequency point in the current-voltage frequency phase stable correlation data. For the frequency points where there is a risk of resonance, the matching suppression impedance is recalculated. Assuming that at the 96Hz resonant frequency point, according to the stabilized current-voltage phase relationship, the original designed LC filter parameters are inductance ,capacitance , now through calculation, we find that the inductance needs to be adjusted to , the capacitance is adjusted to To better match the phase relationship and enhance the resonance suppression effect, a suitable impedance element is selected to construct the suppression impedance combination. The electric reactor is a silicon steel sheet electric reactor, and the capacitor is a metallized polypropylene film capacitor. According to the optimized parameters and connection mode, the suppression impedance combination is installed in the three-phase circuit of the combined transformer, and the electrical connection of each element is ensured to be tight and the insulation performance is good. After installation, actual testing and verification are carried out. A current signal containing the resonance frequency components is injected at the primary side of the combined transformer, and the current, voltage amplitude and phase change at the secondary side are monitored through a high-precision phase detector and a power analyzer. If the current amplitude is 20A at the frequency point of 96Hz, the current amplitude at the secondary side is reduced to 5A after the suppression impedance combination processing, and the phase difference between the current and the voltage remains stable, indicating that the resonance matching suppression effect is good.

[0129] Further, step S5 includes the following steps:

[0130] Step S51: According to the resonance matching suppression impedance combination data, the time sequence and current-voltage impedance fluctuation of each frequency band of the combined transformer are analyzed, and time sequence-current-voltage impedance fluctuation data of each frequency band is generated.

[0131] In the embodiment of the present application, the frequency range is divided into multiple frequency bands, such as 0-50Hz for low frequency band, 51-150Hz for low-middle frequency band, 151-500Hz for middle-high frequency band, and 501Hz and above for high frequency band. High-precision current transformers and voltage transformers are used to collect the current and voltage instantaneous values of each node in the three-phase circuit of the combined transformer at a sampling frequency of 5000Hz. For each frequency band, a sliding window algorithm is used, with 100 sampling points as a window, to calculate the effective value of the current and voltage in the window. The impedance fluctuation with time in each frequency band is analyzed, and the change rate of the impedance values of adjacent windows is calculated. A threshold is set to determine whether the fluctuation is abnormal, and when the change rate exceeds 5%, it is marked as abnormal fluctuation. The current, voltage, impedance values, fluctuation change rate, abnormal marker and other information at different times of each frequency band are sorted to generate time sequence-current-voltage impedance fluctuation data of each frequency band containing frequency band number, time stamp, three-phase current value, three-phase voltage value, three-phase impedance value, impedance fluctuation change rate, and abnormal marker.

[0132] Step S52: According to the time sequence-current-voltage impedance fluctuation data of each frequency band, three-phase current-voltage harmonic decoupling processing of the combined transformer is performed to generate three-phase current-voltage harmonic decoupling data;

[0133] In this embodiment of the present invention, a fast Fourier transform (FFT) algorithm is used to perform spectrum analysis on the time domain signals of the three-phase current and voltage, decomposing them into fundamental and harmonic components. Taking the phase A current signal as an example, an FFT operation is performed on 2048 consecutive sampling points to obtain its amplitude and phase information at different frequencies. A harmonic decoupling model is established, and the harmonic impedance matrix is ​​used to describe the harmonic coupling relationship between the three phases. Assume that the three-phase harmonic impedance matrix is ,in express to similar Subharmonic impedance. Based on the current and voltage values ​​at each harmonic frequency and the harmonic impedance matrix, the independent harmonic current and voltage components of each phase are solved through matrix operations. For example, for the 5th harmonic, it is known that the 5th harmonic amplitude of the A phase voltage is 20V, the phase is 30°, and the 5th harmonic amplitude of the B phase current is 10A, the phase is -45°. Combined with the harmonic impedance matrix, and The value of , solving for the independent 5th harmonic voltage components of phase A. The independent current, voltage amplitude, and phase information of each three-phase harmonic are collated to generate three-phase current and voltage harmonic decoupling data including harmonic order, three-phase current harmonic amplitude, three-phase current harmonic phase, three-phase voltage harmonic amplitude, and three-phase voltage harmonic phase.

[0134] Step S53: Calculating the three-phase current, voltage, and impedance balance deviation of the combined transformer based on the three-phase current and voltage harmonic decoupling data to generate three-phase current, voltage, and impedance balance deviation data;

[0135] In the embodiment of the present invention, first, the impedance values ​​of the three phases at each harmonic frequency are calculated, according to the formula ( is the harmonic voltage amplitude, is the harmonic current amplitude). To determine the balanced reference value of the three-phase impedance, take the average impedance of the three phases at each harmonic frequency as a reference. For example, at the 7th harmonic, the impedance of phase A is 1.875Ω, phase B is 1.9Ω, and phase C is 1.8Ω. Calculate and obtain the average impedance. Then, calculate the degree of deviation of the three-phase harmonic impedance from the balanced reference value, and use the formula ( is the harmonic impedance of a phase, The impedance deviation of phase A at the seventh harmonic is calculated using the average impedance. A deviation threshold is set, and when the deviation of a phase exceeds 3%, it is considered unbalanced. The impedance balance deviation of the three phases at all subharmonic frequencies is calculated and determined.

[0136] Step S54: Based on the three-phase current voltage impedance balance deviation data, the three-phase current voltage impedance attenuation detection of the combined transformer is performed on the time sequence-current voltage impedance fluctuation data of each frequency band, and three-phase current voltage impedance attenuation data is generated.

[0137] In the embodiment of the present application, the attenuation trend of three-phase impedance in each frequency band is analyzed in combination with the three-phase current voltage impedance balance deviation data. For each frequency band, multiple time nodes are selected, and the impedance values of adjacent time nodes are compared. For example, in the high frequency band, the impedance values at time points and are 22Ω, the impedance attenuation amount is calculated as , and the reduction rate is . The attenuation threshold is set, and when the impedance attenuation rate of a phase in a frequency band exceeds 10%, it is judged that the phase has abnormal attenuation. Considering the mutual influence between the three phases, if the impedance of a phase is abnormally attenuated, the coupling influence of the impedance of the other two phases is analyzed. When the A-phase has abnormal attenuation in a certain frequency band, the impedance change amount of the B-phase and the C-phase caused by the attenuation of the A-phase is calculated through the coupling relationship in the three-phase current voltage impedance balance deviation data. The three-phase current voltage impedance attenuation data including the frequency band number, the time stamp, the three-phase impedance attenuation amount, the three-phase impedance attenuation rate, the abnormal attenuation mark, and the coupling influence analysis are generated by arranging the three-phase impedance attenuation amount, the three-phase impedance attenuation rate, the judgment result of whether the attenuation is abnormal, and the coupling influence analysis of the three phases at different times in each frequency band.

[0138] Step S55: According to the three-phase current voltage impedance attenuation data, the three-phase current voltage suppression compensation parameter design of the combined transformer is performed, and three-phase current voltage suppression compensation parameter data is generated. The three-phase current voltage suppression compensation parameter data is transmitted to the combined transformer to perform resonance suppression protection.

[0139] In the embodiment of the present application, a compensation scheme is designed for the abnormal situation shown in the three-phase current voltage impedance attenuation data. When the impedance of a certain phase is excessively attenuated in a specific frequency band, the compensation impedance value is calculated according to the attenuation degree and system requirements. For example, if the impedance attenuation rate of the A-phase reaches 15% in the medium-high frequency band, in order to restore the impedance to the normal level, the compensation inductance value or the compensation capacitance value in series or parallel is calculated according to the circuit principle. Assuming that an inductance needs to be connected in series according to the calculation, the center frequency of the frequency band is , and the compensation impedance value is determined in combination with the impedance value that needs to be compensated according to the formula ​The specific parameters of the three-phase current and voltage compensation control strategy are designed, and the balance relationship among the three phases is considered. When the A phase is compensated, the compensation parameters of the B and C phases are adjusted at the same time to ensure the balance of the three-phase current and voltage. The proportional-integral-derivative (PID) control algorithm is adopted to dynamically adjust the compensation parameters according to the real-time impedance attenuation data. The designed three-phase current and voltage suppression compensation parameters are transmitted to the built-in intelligent control unit of the combined transformer through a dedicated communication interface (such as RS-485 bus). The intelligent control unit controls the corresponding compensation device (such as controllable reactor and adjustable capacitor) to act according to the received parameter data, so as to realize the resonance suppression protection of the combined transformer and ensure its stable operation.

[0140] Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the application being defined by the appended claims and not by the above description, therefore all variations falling within the meaning and scope of the equivalent requirements of the application file are intended to be included in the present application.

[0141] The above description is merely a specific implementation of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer, characterized in that: The following steps are involved: Step S1: Acquire combined transformer data; perform three-phase mutual electrical parameter-topology mapping processing of the combined transformer according to the combined transformer data to generate three-phase mutual electrical parameter-topology mapping data; Step S2: performing three-phase current and voltage interaction impedance linkage analysis of the combined transformer according to the three-phase interaction electrical parameter-topology mapping data to generate three-phase current-voltage interaction impedance linkage data; Step S3: collecting outdoor environment detection data of the combined mutual inductor through a sensor; performing external environment electric field-magnetic field fluctuation detection of the combined mutual inductor based on the outdoor environment detection data to generate external environment electric field-magnetic field fluctuation data; Step S4: performing resonance matching suppression impedance combination processing of the combined mutual inductor based on the external environment electric field-magnetic field fluctuation data and the three-phase current-voltage mutual inductance impedance linkage data to generate resonance matching suppression impedance combination data; Step S5: Design the three-phase current and voltage suppression compensation parameters of the combined transformer according to the resonance matching suppression impedance combination data, generate three-phase current and voltage suppression compensation parameter data, and perform resonance suppression protection by transmitting the three-phase current and voltage suppression compensation parameter data to the combined transformer.

2. The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer according to claim 1 is characterized in that: Step S1 includes the following steps: Step S11: Acquire combined transformer data; Step S12: performing three-phase electrical signal parameter analysis of the combined sensor according to the combined mutual inductor data to generate three-phase electrical signal parameter data of the combined sensor; Step S13: Acquire the combined sensor structure data, perform combined sensor unit link analysis based on the combined sensor structure data, and generate combined sensor unit link data; Step S14: performing response-associated combined mutual inductor analysis of each electrical signal control range on the combined sensor unit link data based on the three-phase electrical signal parameter data of the combined sensor, and generating response-associated combined mutual inductor data corresponding to each electrical signal control range; Step S15: performing three-phase interactive electrical parameter-topology mapping processing of the combined transformer based on the response-associated combined transformer data and the combined sensor unit link data corresponding to each electrical signal control range to generate three-phase interactive electrical parameter-topology mapping data.

3. The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer according to claim 1 is characterized in that: Step S2 includes the following steps: Step S21: performing a three-phase mutual inductance current loop analysis of the combined mutual inductor according to the three-phase mutual electrical parameter-topology mapping data to generate three-phase mutual inductance current loop data; Step S22: performing three-phase electric field coupling distribution analysis of the combined mutual inductor according to the three-phase mutual inductance current loop data to generate three-phase electric field coupling distribution data; Step S23: performing a three-phase coupled electric field strength deviation evaluation of the combined mutual inductor on the three-phase electric field coupling distribution data to generate three-phase coupled electric field strength deviation data; Step S24: performing a three-phase induced voltage coupling response analysis of the combined transformer on the electric field coupling distribution data based on the three-phase coupled electric field strength deviation data to generate three-phase induced voltage coupling response data; Step S25: performing three-phase current and voltage interaction impedance linkage analysis of the combined transformer according to the three-phase interaction current loop data and the three-phase induced voltage coupling response data to generate three-phase current-voltage interaction impedance linkage data.

4. The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer according to claim 3 is characterized in that: Step S25 includes the following steps: Step S251: performing a three-phase current interaction response analysis of the combined transformer according to the three-phase interaction current loop data to generate three-phase current interaction response data; Step S252: performing frequency domain analysis processing of the three-phase voltage of the combined transformer according to the three-phase induced voltage coupling response data to generate three-phase voltage frequency domain analysis data; Step S253: extracting the frequency domain spectrum of the three-phase current and voltage coupling response of the combined transformer based on the three-phase current interaction response data and generating the three-phase current-voltage coupling response frequency domain spectrum data; Step S254: analyzing the three-phase mutual inductance loop current-voltage-impedance coupling characteristics of the combined mutual inductor according to the three-phase current-voltage coupling response frequency domain spectrum data, and generating three-phase mutual inductance loop current-voltage-impedance coupling characteristics data; Step S255: performing three-phase current and voltage interaction impedance linkage analysis of the combined transformer according to the three-phase interaction loop current-voltage-impedance coupling characteristic data to generate three-phase current-voltage interaction impedance linkage data.

5. The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer according to claim 1, characterized in that: Step S3 includes the following steps: Step S31: collecting outdoor environment detection data of the combined mutual inductor through a sensor, and performing outdoor electric field and magnetic field frequency domain conversion processing on the outdoor environment detection data to generate outdoor electric field-magnetic field frequency domain conversion data; Step S32: Analyze the outdoor electric field and magnetic field strength of the combined mutual inductor according to the outdoor electric field-magnetic field frequency domain conversion data to generate outdoor electric field-magnetic field strength data; Step S33: Analyzing the outdoor environment impact factors of the combined mutual inductor according to the outdoor environment detection data to generate outdoor environment impact factor data; Step S34: performing an electric field-magnetic field interference evaluation of the combined mutual inductor on the outdoor electric field-magnetic field strength data based on the outdoor environmental impact factor data to generate electric field-magnetic field interference data; Step S35: performing external environment electric field-magnetic field fluctuation detection on the combined mutual inductor according to the electric field-magnetic field interference data, and generating external environment electric field-magnetic field fluctuation data.

6. The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer according to claim 1, characterized in that: Step S4 includes the following steps: Step S41: performing a current and voltage frequency coupling analysis of the combined transformer based on the external environment electric field-magnetic field fluctuation data and the three-phase current-voltage mutual impedance linkage data to generate current-voltage frequency coupling data; Step S42: performing equivalent load capacitance and inductance analysis of the combined transformer based on the three-phase current-voltage mutual impedance linkage data to generate equivalent load capacitance-inductance data; Step S43: Identifying the current and voltage resonance response amplitude of the combined transformer based on the current-voltage frequency coupling data and the equivalent load capacitance-inductance data, and generating current and voltage resonance response amplitude data; Step S44: performing resonance matching suppression impedance combination processing of the combined mutual inductor based on the equivalent load capacitance-inductance data and the current-voltage resonance response amplitude data to generate resonance matching suppression impedance combination data.

7. The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer according to claim 6, characterized in that: Step S42 includes the following steps: Step S421: performing current mutual inductive coupling link analysis of the combined transformer according to the three-phase current-voltage mutual inductive impedance linkage data to generate current mutual inductive coupling link data; Step S422: performing load link voltage change detection of the combined transformer according to the current mutual inductive coupling link data to generate load link voltage change data; Step S423: performing current and voltage frequency domain and load link capacitance response analysis of the combined transformer based on the load link voltage change data and the current mutual inductive coupling link data to generate current and voltage frequency domain-load link capacitance response data; Step S424: performing equivalent load capacitance and inductance analysis of the combined transformer based on the current-voltage frequency domain-load link capacitance response data to generate equivalent load capacitance-inductance data.

8. The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer according to claim 6, characterized in that: Step S44 includes the following steps: Step S441: performing a current-voltage combined resonant frequency domain analysis of the combined transformer according to the equivalent load capacitance-inductance data to generate current-voltage combined resonant frequency domain data; Step S442: evaluating the current and voltage resonance intensity and response sensitivity of the combined transformer based on the current and voltage resonance response amplitude data and the current and voltage combined resonance frequency domain data, to generate current and voltage resonance intensity-sensitivity evaluation data; Step S443: performing low-impedance current-voltage combined filtering analysis of the combined transformer according to the current-voltage resonance intensity-sensitivity evaluation data to generate low-impedance current-voltage combined filtering data; Step S444: performing resonance matching suppression impedance combination processing of the combined mutual inductor according to the low-impedance current-voltage combination filtering data to generate resonance matching suppression impedance combination data.

9. The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer according to claim 8, characterized in that: Step S444 includes the following steps: Identify the current and voltage fluctuation-related phases of the combined transformer based on the low-impedance current and voltage combined filtering data to generate current-voltage fluctuation-related phase data; Evaluate the combined current and voltage frequency domain phase offset of the combined transformer based on the current-voltage fluctuation correlation phase data to generate combined current and voltage frequency domain phase offset data; Based on the combined current and voltage frequency domain phase offset data, the current-voltage fluctuation correlation phase data is subjected to the current and voltage frequency phase stability correlation processing of the combined transformer to generate current-voltage frequency phase stability correlation data; Based on the current-voltage frequency-phase stable correlation data, the low-impedance current-voltage combination filtering data is subjected to a resonance matching suppression impedance combination process of the combination transformer to generate resonance matching suppression impedance combination data.

10. The resonance suppression protection method for an outdoor three-phase integrated low-impedance voltage combination transformer according to claim 1, characterized in that: Step S5 includes the following steps: Step S51: analyzing the timing of each frequency band and the current and voltage impedance fluctuation of the combined mutual inductor according to the resonant matching suppression impedance combination data, and generating timing-current and voltage impedance fluctuation data of each frequency band; Step S52: performing three-phase current and voltage harmonic decoupling processing of the combined transformer according to the time series-current, voltage and impedance fluctuation data of each frequency band to generate three-phase current and voltage harmonic decoupling data; Step S53: Calculating the three-phase current, voltage, and impedance balance deviation of the combined transformer based on the three-phase current and voltage harmonic decoupling data to generate three-phase current, voltage, and impedance balance deviation data; Step S54: performing three-phase current, voltage and impedance attenuation detection of the combined transformer on the time series-current, voltage and impedance fluctuation data of each frequency band based on the three-phase current, voltage and impedance balance deviation data to generate three-phase current, voltage and impedance attenuation data; Step S55: Design the three-phase current and voltage suppression compensation parameters of the combined transformer according to the three-phase current and voltage impedance attenuation data, generate three-phase current and voltage suppression compensation parameter data, and perform resonance suppression protection by transmitting the three-phase current and voltage suppression compensation parameter data to the combined transformer.

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