Anti-electromagnetic interference device and anti-electromagnetic interference method for field inspection device of transformer monitoring device

Abstract

The invention relates to the field of anti-electromagnetic interference, in particular to an anti-electromagnetic interference method for a field inspection device of a transformer monitoring device, which comprises the following steps of: actually measuring a transformer substation, and performing simulation excitation processing by utilizing environmental interference data of the transformer monitoring inspection device to obtain an electromagnetic interference shielding simulation result of the transformer monitoring inspection device; acquiring a high-frequency electromagnetic noise suppression result of the transformer monitoring and checking device based on Matlab by taking the environmental interference data as an excitation condition; and performing verification processing on the electromagnetic interference shielding simulation result and the high-frequency electromagnetic noise suppression result of the transformer monitoring and checking device to obtain an anti-electromagnetic interference result of the transformer monitoring and checking device. The acquisition precision of sensing signals and the stability of data transmission are effectively improved.

Description

Technical Field

[0001] The invention relates to the field of anti-electromagnetic interference, and in particular to an anti-electromagnetic interference method for an on-site inspection device of a transformer monitoring device. Background Art

[0002] The transformer monitoring device ensures the safe and reliable operation of the transformer by real-time monitoring of equipment status and fault diagnosis, thereby improving the stability of the power system. The on-site detection device of the transformer comprehensive monitoring device is used to check whether the monitoring equipment has problems such as aging, decreased sensitivity, and damage, so as to avoid the transformer from being in a "blind running" state.

[0003] With the promotion of smart grid, many new electromagnetic equipment have been put into operation, resulting in many new electromagnetic interference sources, which make substations and converter stations have complex electromagnetic environment for a long time. The on-site verification device of transformer monitoring device must work in this environment and will inevitably receive strong electromagnetic interference, thus affecting the collection of sensor signals and making it impossible to accurately test the performance of transformer monitoring device.

[0004] Since the electromagnetic interference of substations and converter stations has a significant impact on the accuracy and effectiveness of the signals collected by the on-site inspection device of the transformer monitoring device, it is particularly important to design the on-site inspection device to resist electromagnetic interference. By electromagnetically shielding the shell of the on-site inspection device and filtering its power line and signal line, the electromagnetic interference of the device can be effectively reduced, and the accuracy and stability of the device can be improved. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides an anti-electromagnetic interference method for a field inspection device of a transformer monitoring device. By measuring the electromagnetic interference sources at the substation and converter station sites, the type, frequency, amplitude and other data of the interference sources are obtained and aligned for analysis and research. According to the measured interference data, an anti-interference strategy combining shielding and filtering is selected.

[0006] To achieve the above object, the present invention provides an anti-electromagnetic interference method for a transformer monitoring device on-site inspection device, which is characterized by comprising:

[0007] The environmental interference data of the transformer monitoring and testing device is used to perform simulation excitation processing to obtain the electromagnetic interference shielding simulation result of the transformer monitoring and testing device;

[0008] Using the environmental interference data as an excitation condition, obtaining a high-frequency electromagnetic noise suppression result of a transformer monitoring and testing device based on Matlab;

[0009] The electromagnetic interference shielding simulation result and the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device are used to perform verification processing to obtain the anti-electromagnetic interference result of the transformer monitoring and testing device.

[0010] Preferably, the use of environmental interference data of the transformer monitoring and testing device to perform simulation excitation processing to obtain the electromagnetic interference shielding simulation result of the transformer monitoring and testing device includes:

[0011] Obtain environmental interference data of transformer monitoring and inspection equipment;

[0012] Respectively obtain the shielding shell shape and shielding shell material of the transformer monitoring and testing device;

[0013] The environmental interference data is used to perform simulation excitation processing based on Ansys according to the shape and material of the shielding shell to obtain the electromagnetic interference shielding simulation result of the transformer monitoring and testing device.

[0014] Furthermore, the step of obtaining environmental interference data of the transformer monitoring and testing device includes:

[0015] Obtain the types of interference sources of the transformer monitoring and testing device;

[0016] According to the type of the interference source, corresponding transient electromagnetic wave magnetic field, high-frequency harmonic amplitude, current waveform distortion data and magnetic field leakage data are respectively obtained as environmental interference data.

[0017] Furthermore, obtaining corresponding transient electromagnetic wave magnetic field, high-frequency harmonic amplitude, current waveform distortion data and magnetic field leakage data as environmental interference data according to the type of interference source includes:

[0018] The calculation formula for obtaining the transient electromagnetic wave magnetic field corresponding to the high voltage and current change of the transformer monitoring and testing device according to the type of the interference source is as follows:

[0019]

[0020] Wherein, E is the magnetic field corresponding to the transient electromagnetic wave, and A is the magnetic vector potential;

[0021] The calculation formula for obtaining the high-frequency harmonic amplitude corresponding to the transformer monitoring and inspection device according to the type of the interference source is as follows:

[0022] I(t)=I1sin(ωt)+I2sin(2ωt)+I3sin(3ωt)+…

[0023] Wherein, I1, I2, I3 are the amplitudes corresponding to different harmonics, and ω is the base rate;

[0024] The calculation formula for obtaining the current waveform distortion data corresponding to the nonlinear load of the transformer monitoring and testing device according to the type of the interference source is as follows:

[0025] I(t)=I0cos(ωt+φ)

[0026] Where, I(t) is the current waveform distortion data, ω is the frequency corresponding to the nonlinear load, and φ is the phase corresponding to the nonlinear load;

[0027] The calculation formula for obtaining the magnetic field leakage corresponding to the magnetic induction intensity of the transformer monitoring and testing device as magnetic field leakage data according to the type of the interference source is as follows:

[0028] B=μ(H+M)

[0029] Among them, B is the magnetic induction intensity, μ is the magnetic permeability, H is the magnetic field intensity, and M is the magnetization intensity.

[0030] Furthermore, the electromagnetic interference shielding simulation results of the transformer monitoring and inspection device are obtained by using the environmental interference data to perform simulation excitation processing based on Ansys according to the shape of the shielding shell and the material of the shielding shell, including:

[0031] Using the environmental interference data, obtaining the corresponding electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth according to the shape of the shielding shell and the material of the shielding shell;

[0032] Establishing an electromagnetic shielding mathematical model by performing simulation excitation processing according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth;

[0033] According to the electromagnetic shielding mathematical model, the shielding effectiveness simulation processing is performed based on Ansys to obtain the electromagnetic interference shielding simulation result.

[0034] Further, using the environmental interference data to obtain the corresponding electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth according to the shielding shell shape and the shielding shell material includes:

[0035] The calculation formula for obtaining the corresponding electromagnetic shielding effectiveness according to the shape and material of the shielding shell using the environmental interference data is as follows:

[0036]

[0037] Among them, SE is the electromagnetic shielding effectiveness, Pi is the incident power, and Po is the power after passing through the shielding material;

[0038] The calculation formula for obtaining the corresponding electromagnetic reflection loss based on the shape and material of the shielding shell using the environmental interference data is as follows:

[0039]

[0040] Where RL is the electromagnetic reflection loss, Zm is the impedance of the material, and Zf is the impedance of free space;

[0041] The calculation formula for obtaining the corresponding electromagnetic transmission loss based on the shape and material of the shielding shell using the environmental interference data is as follows:

[0042]

[0043] Where TL is the electromagnetic transmission loss, Pi is the incident power, and Po is the power after passing through the shielding material;

[0044] The calculation formula for obtaining the corresponding electromagnetic shielding depth according to the shape and material of the shielding shell using the environmental interference data is as follows:

[0045]

[0046] Among them, δ is the electromagnetic shielding depth, f is the electromagnetic wave frequency, μr is the relative magnetic permeability of the material, and σ is the electrical conductivity of the material.

[0047] Furthermore, the electromagnetic shielding mathematical model is established by performing simulation excitation processing according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth, including:

[0048] According to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth, the calculation formula of Maxwell equations is established based on Ansys simulation excitation processing as follows:

[0049]

[0050] Among them, E is the electric field, H is the magnetic field, B is the magnetic induction intensity, D is the electric displacement, ρ is the charge density, and J is the current density;

[0051] The calculation formula for obtaining the corresponding wave impedance according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth is as follows:

[0052]

[0053] Where Z is the wave impedance, μ is the magnetic permeability of the material, and ∈ is the dielectric constant of the material;

[0054] The calculation formula for obtaining the corresponding complex dielectric constant according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth is as follows:

[0055] ε=ε'-jε"

[0056] Where ∈r is the complex dielectric constant, ∈′ is the real part of the material, and ∈″ is the imaginary part of the material

[0057] The calculation formula for obtaining the frequency dependence of the corresponding cutoff frequency and shielding effectiveness according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth is as follows:

[0058]

[0059] Where, SE(f) is the frequency dependence of cut-off frequency and shielding effectiveness, f is the frequency of electromagnetic wave, and fc is the cut-off frequency of the material;

[0060] The electromagnetic shielding mathematical model is established by using the Maxwell equations, wave impedance, complex dielectric constant, cut-off frequency and frequency dependence of shielding effectiveness.

[0061] Furthermore, the electromagnetic interference shielding simulation result is obtained by performing simulation shielding effectiveness processing based on Ansys according to the electromagnetic shielding mathematical model as follows:

[0062]

[0063] Among them, E is the electric field intensity, H is the magnetic field intensity, μ is the magnetic permeability, and ∈ is the dielectric constant.

[0064] 9. The anti-electromagnetic interference method of a transformer monitoring device on-site inspection device according to claim 5, characterized in that the high-frequency electromagnetic noise suppression result of the transformer monitoring and inspection device is obtained based on Matlab using the environmental interference data as an excitation condition, comprising:

[0065] The calculation formula for obtaining the cutoff frequency of the RC filter circuit corresponding to the transformer monitoring and testing device is as follows:

[0066]

[0067] Where, fc is the cutoff frequency of the RC filter circuit, R is the resistor, and C is the capacitor;

[0068] The calculation formula for obtaining the transfer function of the RC filter circuit corresponding to the transformer monitoring and testing device is as follows:

[0069]

[0070] Where H(s1) is the transfer function of the RC filter circuit, s is the complex frequency variable, ω=2πf;

[0071] The calculation formula for obtaining the cutoff frequency of the π-type circuit corresponding to the transformer monitoring and testing device is as follows:

[0072]

[0073] Where fc is the cutoff frequency of the π-type circuit, L is the inductance value; C1 and C2 are the input and output capacitance values, and L(C1+C2) represents the resonant characteristics of the circuit;

[0074] The calculation formula for obtaining the transfer function of the π-type circuit corresponding to the transformer monitoring and testing device is as follows:

[0075]

[0076] Where H(s2) is the transfer function of the π-type circuit, C1 and C2 are the input and output capacitance values, and s is the complex frequency variable;

[0077] The calculation formula of the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device is obtained by performing simulation filtering performance processing based on Matlab using the cutoff frequency of the RC filter circuit corresponding to the transformer monitoring and testing device, the transmission function of the RC filter circuit, the cutoff frequency of the π-type circuit, and the transmission function of the π-type circuit as follows:

[0078]

[0079] Where H(s1) is the transfer function of the RC filter circuit, H(s2) is the transfer function of the π-type circuit, R is the resistor, C is the capacitor, s is the complex frequency variable, C1 and C2 are the input and output capacitor values, and ω=2πf.

[0080] Furthermore, the electromagnetic interference shielding simulation result and the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device are used to verify and process the anti-electromagnetic interference result of the transformer monitoring and testing device, including:

[0081] The electromagnetic interference shielding simulation result and the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device are used to perform on-site working condition test processing to obtain the anti-electromagnetic interference result of the transformer monitoring and testing device.

[0082] Compared with the closest prior art, the present invention has the following beneficial effects:

[0083] The present invention provides an anti-electromagnetic interference device and method for a transformer monitoring device field inspection device, which has broad application prospects in engineering practice. The present invention optimizes the anti-interference design of the transformer monitoring device field inspection device, and comprehensively adopts technical means such as electromagnetic shielding, filtering processing, and signal conditioning, effectively suppresses the influence of various interference sources in a complex electromagnetic environment, significantly improves the acquisition accuracy of the sensor signal, and ensures the stability and reliability of data transmission, thereby further improving the overall performance of the equipment during field operation, and providing important technical support for the accuracy and safety of transformer monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 It is a flow chart of an anti-electromagnetic interference method of a transformer monitoring device on-site inspection device provided by the present invention;

[0085] Figure 2 It is a practical application flow chart of an anti-electromagnetic interference method of a transformer monitoring device on-site inspection device provided by the present invention. DETAILED DESCRIPTION

[0086] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0087] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0088] Embodiment 1:

[0089] The present invention provides an anti-electromagnetic interference method for a transformer monitoring device on-site inspection device, such as Figure 1 As shown, including:

[0090] S1. Using the environmental interference data of the transformer monitoring and testing device to perform simulation excitation processing to obtain the electromagnetic interference shielding simulation result of the transformer monitoring and testing device;

[0091] S2. Using the environmental interference data as an excitation condition to obtain a high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device based on Matlab;

[0092] S3. Using the electromagnetic interference shielding simulation result and the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device to perform verification processing to obtain the anti-electromagnetic interference result of the transformer monitoring and testing device.

[0093] S1 specifically includes:

[0094] S1-1. Obtain environmental interference data of the transformer monitoring and inspection device;

[0095] S1-2, respectively obtaining the shielding shell shape and shielding shell material of the transformer monitoring and testing device;

[0096] S1-3. Using the environmental interference data, a simulation excitation process is performed based on Ansys according to the shape and material of the shielding shell to obtain an electromagnetic interference shielding simulation result of the transformer monitoring and testing device.

[0097] S1-1 specifically includes:

[0098] S1-1-1. Obtain the types of interference sources of the transformer monitoring and testing device;

[0099] S1-1-2. According to the type of interference source, corresponding transient electromagnetic wave magnetic field, high-frequency harmonic amplitude, current waveform distortion data and magnetic field leakage data are obtained as environmental interference data.

[0100] S1-1-2 specifically includes:

[0101] S1-1-2-1. The calculation formula for obtaining the transient electromagnetic wave magnetic field corresponding to the high voltage and current change of the transformer monitoring and inspection device according to the type of the interference source is as follows:

[0102]

[0103] Wherein, E is the magnetic field corresponding to the transient electromagnetic wave, and A is the magnetic vector potential;

[0104] S1-1-2-2. The calculation formula for obtaining the high-frequency harmonic amplitude corresponding to the transformer monitoring and inspection device according to the type of interference source is as follows:

[0105] I(t)=I1sin(ωt)+I2sin(2ωt)+I3sin(3ωt)+…

[0106] Wherein, I1, I2, I3 are the amplitudes corresponding to different harmonics, and ω is the base rate;

[0107] S1-1-2-3. The calculation formula for obtaining the current waveform distortion data corresponding to the nonlinear load of the transformer monitoring and testing device according to the type of the interference source is as follows:

[0108] I(t)=I0cos(ωt+φ)

[0109] Where, I(t) is the current waveform distortion data, ω is the frequency corresponding to the nonlinear load, and φ is the phase corresponding to the nonlinear load;

[0110] S1-1-2-4. The calculation formula for obtaining the magnetic field leakage corresponding to the magnetic induction intensity of the transformer monitoring and testing device as the magnetic field leakage data according to the type of the interference source is as follows:

[0111] B=μ(H+M)

[0112] Among them, B is the magnetic induction intensity, μ is the magnetic permeability, H is the magnetic field intensity, and M is the magnetization intensity.

[0113] S1-3 specifically includes:

[0114] S1-3-1, using the environmental interference data to obtain the corresponding electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth according to the shape of the shielding shell and the material of the shielding shell;

[0115] S1-3-2, establishing an electromagnetic shielding mathematical model by performing simulation excitation processing according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth;

[0116] S1-3-3. Perform shielding effectiveness simulation based on Ansys according to the electromagnetic shielding mathematical model to obtain electromagnetic interference shielding simulation results.

[0117] S1-3-1 specifically includes:

[0118] S1-3-1-1. The calculation formula for obtaining the corresponding electromagnetic shielding effectiveness according to the shape and material of the shielding shell using the environmental interference data is as follows:

[0119]

[0120] Among them, SE is the electromagnetic shielding effectiveness, P i is the incident power, P o is the power after passing through the shielding material;

[0121] S1-3-1-2. Using the environmental interference data, the calculation formula for obtaining the corresponding electromagnetic reflection loss according to the shielding shell shape and shielding shell material is as follows:

[0122]

[0123] Where RL is the electromagnetic reflection loss, Z m is the impedance of the material, Z f is the impedance of free space;

[0124] S1-3-1-3. Using the environmental interference data, the calculation formula for obtaining the corresponding electromagnetic transmission loss according to the shielding shell shape and shielding shell material is as follows:

[0125]

[0126] Where TL is the electromagnetic transmission loss, P i is the incident power, P o is the power after passing through the shielding material;

[0127] S1-3-1-4. The calculation formula for obtaining the corresponding electromagnetic shielding depth according to the shape and material of the shielding shell using the environmental interference data is as follows:

[0128]

[0129] Among them, δ is the electromagnetic shielding depth, f is the electromagnetic wave frequency, μr is the relative magnetic permeability of the material, and σ is the electrical conductivity of the material.

[0130] S1-3-2 specifically includes:

[0131] S1-3-2-1. According to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth, the calculation formula of Maxwell equations is established based on Ansys simulation excitation processing as follows:

[0132]

[0133] Among them, E is the electric field, H is the magnetic field, B is the magnetic induction intensity, D is the electric displacement, ρ is the charge density, and J is the current density;

[0134] S1-3-2-2. The calculation formula for obtaining the corresponding wave impedance based on the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth is as follows:

[0135]

[0136] Where Z is the wave impedance, μ is the magnetic permeability of the material, and ∈ is the dielectric constant of the material;

[0137] S1-3-2-3. The calculation formula for obtaining the corresponding complex dielectric constant according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth is as follows:

[0138] ε=ε'-jε"

[0139] Where, ∈r is the complex dielectric constant, ∈′ is the real part of the material, and ∈″ is the imaginary part of the material;

[0140] S1-3-2-4. The calculation formula for obtaining the frequency dependence of the corresponding cutoff frequency and shielding effectiveness according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth is as follows:

[0141]

[0142] Where, SE(f) is the frequency dependence of cut-off frequency and shielding effectiveness, f is the frequency of electromagnetic wave, and fc is the cut-off frequency of the material;

[0143] S1-3-2-5. Establish an electromagnetic shielding mathematical model using the Maxwell equations, wave impedance, complex dielectric constant, cut-off frequency and frequency dependence of shielding effectiveness.

[0144] The calculation formula of S1-3-3 is as follows:

[0145]

[0146] Among them, E is the electric field intensity, H is the magnetic field intensity, μ is the magnetic permeability, and ∈ is the dielectric constant.

[0147] S2 specifically includes:

[0148] S2-1. The calculation formula for obtaining the cutoff frequency of the RC filter circuit corresponding to the transformer monitoring and testing device is as follows:

[0149]

[0150] Where, fc is the cutoff frequency of the RC filter circuit, R is the resistor, and C is the capacitor;

[0151] S2-2. The calculation formula for obtaining the transfer function of the RC filter circuit corresponding to the transformer monitoring and testing device is as follows:

[0152]

[0153] Where H(s1) is the transfer function of the RC filter circuit, s is the complex frequency variable, ω=2πf;

[0154] S2-3, the calculation formula for obtaining the cutoff frequency of the π-type circuit corresponding to the transformer monitoring and testing device is as follows:

[0155]

[0156] Where fc is the cutoff frequency of the π-type circuit, L is the inductance value; C1 and C2 are the input and output capacitance values, and L(C1+C2) represents the resonant characteristics of the circuit;

[0157] S2-4, the calculation formula for obtaining the transfer function of the π-type circuit corresponding to the transformer monitoring and testing device is as follows:

[0158]

[0159] Where H(s2) is the transfer function of the π-type circuit, C1 and C2 are the input and output capacitance values, and s is the complex frequency variable;

[0160] S2-5. The calculation formula for the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device is obtained by performing simulation filtering performance processing based on Matlab using the cutoff frequency of the RC filter circuit corresponding to the transformer monitoring and testing device, the transmission function of the RC filter circuit, the cutoff frequency of the π-type circuit, and the transmission function of the π-type circuit. The following is the calculation formula for the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device:

[0161]

[0162] Where H(s1) is the transfer function of the RC filter circuit, H(s2) is the transfer function of the π-type circuit, R is the resistor, C is the capacitor, s is the complex frequency variable, C1 and C2 are the input and output capacitor values, and ω=2πf.

[0163] S3 specifically includes:

[0164] S3-1. Perform field working condition test processing using the electromagnetic interference shielding simulation results and high-frequency electromagnetic noise suppression results of the transformer monitoring and testing device to obtain the anti-electromagnetic interference results of the transformer monitoring and testing device.

[0165] Embodiment 2:

[0166] The present invention provides a practical application method of an anti-electromagnetic interference method of a transformer monitoring device on-site inspection device, such as Figure 2 As shown, including:

[0167] Step 1 (S1), by measuring the actual electromagnetic interference in the substation and converter station, comprehensively analyze the distribution, strength and impact of different types of interference sources on equipment operation, and deeply study the frequency domain and time domain characteristics of electromagnetic interference. Combined with actual working conditions, accurately identify the interference signals generated by substation equipment, high-voltage lines and key components of converter stations, and provide a reliable experimental basis for the subsequent formulation of effective anti-interference design solutions.

[0168] Step 2 (S2), comprehensively analyze and fully consider the measured electromagnetic interference characteristics, conduct a systematic study on the spectrum distribution, time domain waveform and interference intensity of different interference sources, and focus on evaluating their impact on equipment performance and signal transmission. On this basis, combined with field data, an anti-interference plan combining electromagnetic shielding and filtering technology was formulated.

[0169] High voltage and current changes in substations and converter stations generate strong electromagnetic fields, especially when the current changes or switches rapidly. Current changes can induce transient electromagnetic waves and generate electromagnetic interference:

[0170]

[0171] Where E is the electric field and A is the magnetic vector potential;

[0172] The switching operation of equipment (such as circuit breakers, switches, etc.) will generate high-frequency harmonics, which can cause electromagnetic interference:

[0173] I(t)=I1sin(ωt)+I2sin(2ωt)+I3sin(3ωt)+…

[0174] Among them, I1, I2, I3 are the amplitudes of different harmonics, and ω is the base rate;

[0175] Non-linear loads such as power electronic devices can cause current waveform distortion, which in turn generates electromagnetic interference:

[0176] I(t)=I0cos(ωt+φ)

[0177] Where I(t) is the current, ω is the frequency, and φ is the phase;

[0178] Magnetic field leakage from transformers and other equipment in substations can also cause electromagnetic interference, especially when the load changes:

[0179] B=μ(H+M)

[0180] Among them, B is the magnetic induction intensity, μ is the magnetic permeability, H is the magnetic field intensity, and M is the magnetization intensity.

[0181] Step 3 (S3), combining electromagnetic shielding technology and filtering technology, formulate an integrated anti-interference solution, accurately analyze and design different interference sources in complex electromagnetic environments, and achieve effective suppression of interference signals by optimizing shielding materials, structural layout and filtering circuit parameters. At the same time, ensure the integrity of useful signals and the stability of system performance, and provide comprehensive anti-interference protection for the reliable operation of equipment.

[0182] 1) Electromagnetic shielding:

[0183] Shielding effectiveness: An important indicator to measure the effectiveness of shielding materials, usually expressed in decibels (dB):

[0184]

[0185] Where Pi is the incident power and Po is the power after passing through the shielding material;

[0186] Reflection loss: Reflection loss describes the proportion of electromagnetic waves reflected by shielding materials:

[0187]

[0188] Among them, Z m is the impedance of the material, Z f is the impedance of free space;

[0189] Transmission loss: Transmission loss describes the attenuation of electromagnetic waves when passing through shielding materials:

[0190]

[0191] Among them, P i is the incident power, P o is the power after passing through the shielding material;

[0192] Shielding depth: Shielding depth describes the degree to which electromagnetic waves are attenuated in conductive materials:

[0193] Among them, δ is the shielding depth, μ is the magnetic permeability of the material, σ is the electrical conductivity of the material, and ω is the angular frequency of the electromagnetic wave. Maxwell's equations: Shielding depth describes the degree of attenuation of electromagnetic waves in conductive materials:

[0194]

[0195] Among them, E is the electric field, H is the magnetic field, B is the magnetic induction intensity, D is the electric displacement, ρ is the charge density, and J is the current density;

[0196] Wave impedance: For shielding materials, changes in wave impedance have an important impact on reflection and transmission:

[0197]

[0198] Where μ is the magnetic permeability of the material, ∈ is the dielectric constant of the material;

[0199] Complex permittivity: The complex permittivity describes the response of a material to electromagnetic waves:

[0200] Where, ∈r is the complex dielectric constant, ∈′ is the real part of the material, and ∈″ is the imaginary part of the material;

[0201] Cut-off frequency and frequency dependence of shielding effectiveness: The shielding effect of electromagnetic waves at different frequencies will be different. High-frequency electromagnetic waves are usually reflected more effectively by metal materials, while low-frequency electromagnetic waves may require thicker materials or special designs:

[0202]

[0203] Where f is the frequency of the electromagnetic wave, and fc is the cutoff frequency of the material;

[0204] 2) Filtering technology:

[0205] RC filter circuit:

[0206] Circuit structure: Resistor R and capacitor C are connected in series, and the output signal is taken from both ends of the capacitor;

[0207] Cut-off frequency:

[0208]

[0209] Where R is the resistance value; C is the capacitance value;

[0210] Transfer function:

[0211]

[0212] Where s is a complex frequency variable, ω = 2πf;

[0213] Π-type circuit:

[0214] Circuit structure: The Π-type circuit consists of two capacitors C1 and C2 and an inductor L. Capacitor C1 is connected between the input terminal and the ground, inductor L is connected between C1 and C2, and capacitor C2 is connected between the output terminal and the ground;

[0215] Cut-off frequency:

[0216]

[0217] Where L is the inductance value; C1 and C2 are the input and output capacitance values; L(C1+C2) represents the circuit resonance characteristics;

[0218] Transfer function:

[0219]

[0220] Where L is the inductor value; C1 and C2 are the input and output capacitor values, and s is the complex frequency variable.

[0221] Step 4 (S4). Verify the electromagnetic shielding and filtering technology through computer simulation, simulate various interference sources in a complex electromagnetic environment, evaluate the anti-interference effects of different shielding materials, shielding structures and filtering parameters, so as to optimize the design scheme and ensure the feasibility and effectiveness of the anti-interference technology:

[0222] 1) Electromagnetic shielding:

[0223] The shielding effectiveness simulation is performed based on the HFSS (High-Frequency Structure Simulator) simulation module in Ansys. The core equation for solving the electromagnetic wave propagation process is:

[0224]

[0225] Where E is the electric field strength, H is the magnetic field strength, μ is the magnetic permeability, and ∈ is the dielectric constant;

[0226] 2) Filtering technology:

[0227] Based on the Simulink module in Matlab software, the simulation of filtering performance is carried out. The simulation of its filtering capability is solved as follows:

[0228]

[0229] Where L is the inductor value; C1 and C2 are the input and output capacitor values, and s is the complex frequency variable.

[0230] Step 5 (S5).

[0231] The two anti-interference solutions of shielding technology and filtering technology are organically combined, and the on-site verification device of the transformer monitoring device is optimized and designed. By comprehensively considering the electromagnetic interference characteristics under different environments, an efficient anti-interference solution is formed. Subsequently, field tests are carried out under actual working conditions to verify the anti-interference effect of the combined solution and comprehensively evaluate its practical application value in improving the accuracy of sensor signal acquisition and data transmission stability.

[0232] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0233] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0234] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0235] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0236] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device, characterized in that: include: The environmental interference data of the transformer monitoring and testing device is used to perform simulation excitation processing to obtain the electromagnetic interference shielding simulation result of the transformer monitoring and testing device; Using the environmental interference data as an excitation condition, obtaining a high-frequency electromagnetic noise suppression result of a transformer monitoring and testing device based on Matlab; The electromagnetic interference shielding simulation result and the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device are used to perform verification processing to obtain the anti-electromagnetic interference result of the transformer monitoring and testing device.

2. The method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device according to claim 1, characterized in that: The method of using the environmental interference data of the transformer monitoring and testing device to perform simulation excitation processing to obtain the electromagnetic interference shielding simulation result of the transformer monitoring and testing device includes: Obtain environmental interference data of transformer monitoring and inspection equipment; Respectively obtain the shielding shell shape and shielding shell material of the transformer monitoring and testing device; The environmental interference data is used to perform simulation excitation processing based on Ansys according to the shape and material of the shielding shell to obtain the electromagnetic interference shielding simulation result of the transformer monitoring and testing device.

3. The method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device according to claim 2, characterized in that: The step of obtaining environmental interference data of the transformer monitoring and testing device includes: Obtain the types of interference sources of the transformer monitoring and testing device; According to the type of the interference source, corresponding transient electromagnetic wave magnetic field, high-frequency harmonic amplitude, current waveform distortion data and magnetic field leakage data are respectively obtained as environmental interference data.

4. The method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device according to claim 3, characterized in that: According to the type of interference source, the corresponding transient electromagnetic wave magnetic field, high-frequency harmonic amplitude, current waveform distortion data and magnetic field leakage data are obtained as environmental interference data, including: The calculation formula for obtaining the transient electromagnetic wave magnetic field corresponding to the high voltage and current change of the transformer monitoring and testing device according to the type of the interference source is as follows: Wherein, E is the magnetic field corresponding to the transient electromagnetic wave, and A is the magnetic vector potential; The calculation formula for obtaining the high-frequency harmonic amplitude corresponding to the transformer monitoring and inspection device according to the type of the interference source is as follows: I(t)=I1sin(ωt)+I2sin(2ωt)+I3sin(3ωt)+… Wherein, I1, I2, I3 are the amplitudes corresponding to different harmonics, and ω is the base rate; The calculation formula for obtaining the current waveform distortion data corresponding to the nonlinear load of the transformer monitoring and testing device according to the type of the interference source is as follows: I(t)=I0cos(ωt+φ) Where, I(t) is the current waveform distortion data, ω is the frequency corresponding to the nonlinear load, and φ is the phase corresponding to the nonlinear load; The calculation formula for obtaining the magnetic field leakage corresponding to the magnetic induction intensity of the transformer monitoring and testing device as magnetic field leakage data according to the type of the interference source is as follows: B=μ(H+M) Among them, B is the magnetic induction intensity, μ is the magnetic permeability, H is the magnetic field intensity, and M is the magnetization intensity.

5. The method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device according to claim 3, characterized in that: The electromagnetic interference shielding simulation results of the transformer monitoring and inspection device are obtained by using the environmental interference data to perform simulation excitation processing based on Ansys according to the shape and material of the shielding shell, including: Using the environmental interference data, obtaining the corresponding electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth according to the shape of the shielding shell and the material of the shielding shell; Establishing an electromagnetic shielding mathematical model by performing simulation excitation processing according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth; According to the electromagnetic shielding mathematical model, the shielding effectiveness simulation processing is performed based on Ansys to obtain the electromagnetic interference shielding simulation result.

6. The method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device according to claim 5, characterized in that: Using the environmental interference data to obtain the corresponding electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth according to the shape of the shielding shell and the shielding shell material includes: The calculation formula for obtaining the corresponding electromagnetic shielding effectiveness according to the shape and material of the shielding shell using the environmental interference data is as follows: Among them, SE is the electromagnetic shielding effectiveness, P i is the incident power, P o is the power after passing through the shielding material; The calculation formula for obtaining the corresponding electromagnetic reflection loss based on the shape and material of the shielding shell using the environmental interference data is as follows: Where RL is the electromagnetic reflection loss, Z m is the impedance of the material, Z f is the impedance of free space; The calculation formula for obtaining the corresponding electromagnetic transmission loss based on the shape and material of the shielding shell using the environmental interference data is as follows: Where TL is the electromagnetic transmission loss, P i is the incident power, P o is the power after passing through the shielding material; The calculation formula for obtaining the corresponding electromagnetic shielding depth according to the shape and material of the shielding shell using the environmental interference data is as follows: Among them, δ is the electromagnetic shielding depth, f is the electromagnetic wave frequency, μr is the relative magnetic permeability of the material, and σ is the electrical conductivity of the material.

7. The method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device according to claim 6, characterized in that: According to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth, a simulation excitation process is performed to establish an electromagnetic shielding mathematical model, including: According to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth, the calculation formula of Maxwell equations is established based on Ansys simulation excitation processing as follows: Among them, E is the electric field, H is the magnetic field, B is the magnetic induction intensity, D is the electric displacement, ρ is the charge density, and J is the current density; The calculation formula for obtaining the corresponding wave impedance according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth is as follows: Where Z is the wave impedance, μ is the magnetic permeability of the material, and ∈ is the dielectric constant of the material; The calculation formula for obtaining the corresponding complex dielectric constant according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth is as follows: ε=ε'-jε" Among them, ∈ r is the complex dielectric constant, ∈′ is the real part of the material, ∈″ is the imaginary part of the material; The calculation formula for obtaining the frequency dependence of the corresponding cutoff frequency and shielding effectiveness according to the electromagnetic shielding effectiveness, electromagnetic reflection loss, electromagnetic transmission loss and electromagnetic shielding depth is as follows: Where SE(f) is the frequency dependence of the cut-off frequency and shielding effectiveness, f is the frequency of the electromagnetic wave, and f c is the cutoff frequency of the material; The electromagnetic shielding mathematical model is established by using the Maxwell equations, wave impedance, complex dielectric constant, cut-off frequency and frequency dependence of shielding effectiveness.

8. The method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device according to claim 7, characterized in that: According to the electromagnetic shielding mathematical model, the electromagnetic interference shielding simulation result is obtained by performing simulation shielding effectiveness processing based on Ansys as follows: Among them, E is the electric field intensity, H is the magnetic field intensity, μ is the magnetic permeability, and ∈ is the dielectric constant.

9. The method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device according to claim 5, characterized in that: The high-frequency electromagnetic noise suppression results of the transformer monitoring and inspection device are obtained based on Matlab using the environmental interference data as an excitation condition, including: The calculation formula for obtaining the cutoff frequency of the RC filter circuit corresponding to the transformer monitoring and testing device is as follows: Among them, f c is the cut-off frequency of the RC filter circuit, R is the resistor, and C is the capacitor; The calculation formula for obtaining the transfer function of the RC filter circuit corresponding to the transformer monitoring and testing device is as follows: Where H(s1) is the transfer function of the RC filter circuit, s is the complex frequency variable, ω=2πf; The calculation formula for obtaining the cutoff frequency of the π-type circuit corresponding to the transformer monitoring and testing device is as follows: Among them, f c is the cutoff frequency of the π-type circuit, L is the inductance value; C1 and C2 are the input and output capacitance values, and L(C1+C2) represents the resonance characteristics of the circuit; The calculation formula for obtaining the transfer function of the π-type circuit corresponding to the transformer monitoring and testing device is as follows: Where H(s2) is the transfer function of the π-type circuit, C1 and C2 are the input and output capacitance values, and s is the complex frequency variable; The calculation formula of the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device is obtained by performing simulation filtering performance processing based on Matlab using the cutoff frequency of the RC filter circuit corresponding to the transformer monitoring and testing device, the transmission function of the RC filter circuit, the cutoff frequency of the π-type circuit, and the transmission function of the π-type circuit as follows: Where H(s1) is the transfer function of the RC filter circuit, H(s2) is the transfer function of the π-type circuit, R is the resistor, C is the capacitor, s is the complex frequency variable, C1 and C2 are the input and output capacitor values, and ω=2πf.

10. The method for resisting electromagnetic interference of a transformer monitoring device on-site inspection device according to claim 9, characterized in that: The electromagnetic interference shielding simulation results and high-frequency electromagnetic noise suppression results of the transformer monitoring and testing device are used to verify the anti-electromagnetic interference results of the transformer monitoring and testing device, including: The electromagnetic interference shielding simulation result and the high-frequency electromagnetic noise suppression result of the transformer monitoring and testing device are used to perform on-site working condition test processing to obtain the anti-electromagnetic interference result of the transformer monitoring and testing device.

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