Simulation test method and system for researching impedance characteristic rule of circuit breaker under closing resistor damage condition

Abstract

The invention relates to the technical field of circuit breakers, in particular to a simulation test method and system for studying the impedance characteristic law of a circuit breaker under the condition of closing resistor damage, and the method comprises the steps: carrying out the circuit equivalent calculation of other parts except a closing resistor in the circuit breaker, and obtaining the equivalent circuit element parameters of the other parts of the circuit breaker, equivalently replacing other parts of the circuit breaker by using actual circuit elements corresponding to the equivalent circuit element parameters; determining a test closing resistor based on the historical damage condition of the closing resistor of the circuit breaker; a simulation system for hybrid connection of a circuit element and an actual closing resistor is obtained; drawing a sweep frequency impedance curve of the analog circuit based on the impedance amplitude of the analog system under the sine sweep frequency signal; based on the sweep frequency impedance curve of the simulation system of the test closing resistor of the circuit breaker under different damage conditions, the circuit breaker impedance characteristic rule of the test closing resistor of the circuit breaker under the damage conditions is researched.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker technology, and specifically to an analog circuit, device, and method for detecting damage to the closing resistor of a circuit breaker. Background Technology

[0002] As a core component of a circuit breaker, the closing resistor plays a crucial role in ensuring the stable operation of the power system by suppressing inrush current and operational overvoltage during the closing process. However, if the closing resistor is damaged, continuing to perform closing operations will severely impact the normal operation of the circuit breaker. Damage to the closing resistor can easily lead to surface flashover of the resistor insulation column, or gap breakdown due to resistor debris, resulting in circuit breaker failure or even a major accident.

[0003] To clarify the correlation between closing resistance damage and the regular changes in circuit breaker impedance characteristics, some applications rely on disassembling circuit breakers in the field and conducting impedance characteristic tests under damaged conditions. However, this research method has significant limitations: to cover different damage types (such as localized ablation, structural fracture, insulation aging, etc.) and damage degrees (such as minor, moderate, and severe damage), a large number of operating or decommissioned circuit breakers need to be disassembled. This not only consumes a lot of manpower, material resources, and time, resulting in low research efficiency, but also causes significant damage to the integrity of the equipment during on-site disassembly. The operation process is also subject to many limitations due to site conditions, tools, and equipment, making it difficult to operate practically. This research model, which relies on on-site disassembly, restricts in-depth research on the damage mechanism of closing resistance and the evolution of circuit breaker impedance characteristics. Summary of the Invention

[0004] To address the technical problem of low efficiency in studying the relationship between closing resistance damage and circuit breaker impedance characteristics, this invention aims to provide a simulation test method and system for studying the impedance characteristics of circuit breakers under conditions of closing resistance damage. This provides a theoretical basis for future detection of closing resistance damage without disassembling the circuit breaker housing. The specific technical solution adopted is as follows:

[0005] In a first aspect, embodiments of the present invention disclose a simulation test method for studying the impedance characteristics of a circuit breaker under conditions of closing resistor damage. The method includes: performing circuit equivalent calculations on the components of the circuit breaker other than the closing resistor to obtain equivalent circuit element parameters for the remaining components; using the actual circuit elements corresponding to the equivalent circuit element parameters to equivalently replace the remaining components of the circuit breaker; determining the test closing resistor based on the historical damage conditions of the closing resistor; connecting each circuit element and the test closing resistor according to the actual connection relationships of each component in the circuit breaker to obtain a simulation system with a mixed connection of circuit elements and actual closing resistors, thereby achieving equivalent simulation of the electrical performance of the circuit breaker under conditions of closing resistor damage; obtaining the impedance amplitude of the simulation system under a sinusoidal sweep frequency signal, and plotting the sweep frequency impedance curve of the simulation circuit based on the impedance amplitude of the simulation system under a sinusoidal sweep frequency signal; and studying the impedance characteristics of the circuit breaker under damage conditions based on the sweep frequency impedance curves of the simulation system under different damage conditions for the test closing resistor of the circuit breaker.

[0006] Secondly, embodiments of the present invention disclose a simulation test system for studying the impedance characteristics of a circuit breaker under conditions of closing resistor damage. The system includes a circuit breaker simulation system, a signal generator, a power amplifier, a shunt, a signal acquisition device, and electronic equipment. The signal generator is connected to the input terminal of the power amplifier, and the output terminal of the power amplifier is connected to the input terminal of the first parallel branch in the simulation system and the signal acquisition device. The output terminal of the second parallel branch in the simulation system is connected to the input terminal of the shunt, and the output terminal of the shunt is connected to the signal acquisition device. The signal acquisition device is also connected to the electronic equipment. The signal generator outputs a sinusoidal sweep frequency signal to the power amplifier, and the sinusoidal sweep frequency signal is amplified by the power amplifier. The signal is then output through the input terminal of the first parallel branch, the output terminal of the second parallel branch, the input terminal of the shunt, and the output terminal of the shunt in the simulation system. The signal acquisition equipment is used to acquire the output signals of the power amplifier and the shunt, and to process the output signals of the power amplifier and the shunt to obtain the impedance amplitude of the circuit breaker's simulation system under a sinusoidal sweep signal. The electronic equipment is used to plot the sweep impedance curve of the circuit breaker's simulation system based on the impedance amplitude of the simulation system under a sinusoidal sweep signal, and to study the impedance characteristics of the circuit breaker's test closing resistance under damage conditions based on the sweep impedance curve of the simulation system under different damage conditions.

[0007] This invention provides a simulation test method for studying the impedance characteristics of a circuit breaker under conditions of closing resistor damage. First, equivalent circuit calculations are performed on all components of the circuit breaker except the closing resistor to obtain the equivalent circuit element parameters. The actual circuit elements corresponding to these equivalent parameters are then used to equivalently replace the remaining components of the circuit breaker. The test closing resistor is determined based on the historical damage conditions of the circuit breaker's closing resistor. Next, each circuit element and the test closing resistor are connected according to the actual connection relationships of the components in the circuit breaker, resulting in a simulation system with a hybrid connection of circuit elements and the actual closing resistor, achieving an equivalent simulation of the circuit breaker's electrical performance under closing resistor damage conditions. Second, the impedance amplitude of the simulation system under a sinusoidal sweep frequency signal is obtained, and the sweep frequency impedance curve of the simulation circuit is plotted based on this impedance amplitude. Finally, based on the sweep frequency impedance curves of the simulation system under different damage conditions for the test closing resistor of the circuit breaker, the impedance characteristics of the circuit breaker under damage conditions are studied.

[0008] Thus, this invention, through precise circuit equivalent calculations of all components of the circuit breaker except the closing resistor, and by replacing the equivalent components with actual circuit elements, can maximally restore the true internal circuit structure and electrical connections of the circuit breaker. By constructing a hybrid connection simulation system based on the test closing resistor determined from historical damage conditions, high-fidelity electrical performance simulations of the circuit breaker's operating state under different damage types and degrees can be achieved. This provides a test platform close to actual operating conditions for subsequent impedance characteristic research, effectively avoiding research deviations caused by simulation distortion. Furthermore, this invention eliminates the need to disassemble a large number of operating or decommissioned circuit breakers; various damage scenarios can be reproduced through circuit equivalent calculations and simulation system construction, significantly reducing manpower and material costs and shortening the test preparation cycle. Simultaneously, the simulation system allows for flexible adjustment of damage parameters and test conditions in a laboratory environment, facilitating systematic and repetitive frequency sweep tests and data analysis. This effectively solves operational challenges such as site limitations and equipment integrity damage in field research, greatly improving the efficiency and feasibility of studying the impedance characteristics of circuit breakers. By simulating impedance amplitude tests and plotting sweep impedance curves under sinusoidal sweep signals at different frequencies, subtle impedance changes caused by closing resistor damage can be captured from multiple frequency band dimensions. Analysis of the sweep impedance curves under different damage conditions allows for in-depth exploration of the intrinsic correlation between damage type, damage degree, and impedance characteristics. This provides a quantitative basis for accurately identifying the damage state of the closing resistor, helps establish a more scientific damage assessment model, and significantly improves the depth and accuracy of circuit breaker impedance characteristic research. Attached Figure Description

[0009] Figure 1This is a schematic diagram of the internal structure of a circuit breaker provided in an embodiment of the present invention.

[0010] Figure 2 This is a schematic flowchart of a simulation test method for studying the impedance characteristics of a circuit breaker under conditions of closing resistor damage, provided as an embodiment of the present invention.

[0011] Figure 3 This is a schematic diagram of the structure of a simulation system provided in an embodiment of the present invention.

[0012] Figure 4 This is a schematic diagram of a simulation test system for studying the impedance characteristics of a circuit breaker under conditions of closing resistor damage, provided as an embodiment of the present invention.

[0013] Figure 5 This invention provides swept-frequency impedance curves under conditions of damaged closing resistor and undamaged closing resistor. Detailed Implementation

[0014] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a simulation test method and system for studying the impedance characteristics of circuit breakers under conditions of closing resistance damage, proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0016] The following description, in conjunction with the accompanying drawings, details a specific scheme for a simulation test method and system provided by the present invention for studying the impedance characteristics of a circuit breaker under conditions of closing resistor damage.

[0017] like Figure 1 As shown, Figure 1 This is a schematic diagram of the internal structure of a circuit breaker provided in an embodiment of the present invention. Figure 1The circuit breaker includes a closing resistor 10, an input bushing 20, an output bushing 30, a shielding cover 40, a main break 50, an auxiliary break 60, an equalizing capacitor 70, and a central casting 80. All these components are mounted on the circuit breaker housing 90. The input bushing 20 and output bushing 30 are connected to the circuit breaker housing 90 to input and output voltage and current signals. The closing resistor 10 is a rotating series structure; current and voltage signals are input from the input bushing 20 and flow through the closing resistor. The closing resistor 10 is connected to the auxiliary break 60, and the shielding cover 40 is connected to the main break 50. The equalizing capacitor 70 is connected in parallel with the main break 50 on both sides of the closing resistor 10 and the auxiliary break 60. The current signal and voltage signal are input from the input bushing 20 and then flow through the left half of the assembly in turn, then through the central casting 80 to the right side. Subsequently, they flow out in the order of auxiliary break 60 and closing resistor 10 to the output bushing 30.

[0018] Furthermore, from Figure 1 It can be seen that when detecting damage to the closing resistor of a circuit breaker, the main contact needs to be opened and the auxiliary contact closed. Therefore, in the simulation circuit, the main contact is equivalent to a capacitor, and the auxiliary contact is equivalent to a series connection of resistors and inductors. Furthermore, the electrical characteristics of the components inside the circuit breaker, excluding the closing resistor, are mainly capacitive. Therefore, considering the influence of the ground potential tank on the shielding cover and the central casting during operation, the embodiment of this invention uses finite element software simulation to obtain their capacitance to ground. Simultaneously, since they play a connecting role during circuit breaker operation, their own electrical characteristics are basically negligible. Therefore, the subsequent simulation circuit only includes their capacitance to ground. Based on this, in this embodiment of the invention, the equalizing capacitor, shielding cover, and central casting are all equivalent to capacitors. Further, the input-side bushing and output-side bushing inside the circuit breaker have resistive and inductive effects. Therefore, in this embodiment of the invention, the input-side bushing and output-side bushing are equivalent to a parallel connection of resistors and inductors.

[0019] like Figure 2 As shown, Figure 2 A flowchart illustrating a simulation test method for studying the impedance characteristics of a circuit breaker under conditions of closing resistance damage, provided by an embodiment of the present invention, includes:

[0020] Step S201: Perform circuit equivalent calculations on the remaining components of the circuit breaker except for the closing resistor to obtain the equivalent circuit element parameters of the remaining components of the circuit breaker. Use the actual circuit elements corresponding to the equivalent circuit element parameters to replace the remaining components of the circuit breaker. Determine the test closing resistor based on the historical damage status of the closing resistor of the circuit breaker.

[0021] In one optional embodiment of the present invention, the circuit breaker includes: a closing resistor, an input bushing, an output bushing, a shield, a main break, an auxiliary break, a voltage equalizing capacitor, and a central casting. The circuit equivalent calculation of the remaining components of the circuit breaker, excluding the closing resistor, to obtain the equivalent circuit element parameters includes: performing finite element simulation on the remaining components of the circuit breaker to obtain the electrical characteristics of the remaining components; and calculating the circuit element parameters of each component of the circuit breaker based on the electrical characteristics of the remaining components, excluding the closing resistor. In this circuit, the auxiliary break is equivalent to a first resistor and a first inductor. The first resistor, the first inductor, and the closing resistor are connected in series to form a series branch. The main break is equivalent to a first capacitor. The equalizing capacitor is equivalent to a second capacitor. The first capacitor, the second capacitor, and the series branch are connected in parallel. The shielding cover to ground capacitance is equivalent to a third capacitor. The center casting to ground capacitance is equivalent to a fourth capacitor. The input side bushing is equivalent to a second resistor and a fifth capacitor. The second resistor and the fifth capacitor are connected in parallel. The output side bushing is equivalent to a third resistor and a sixth capacitor. The third resistor and the sixth capacitor are connected in parallel.

[0022] Specifically, in this embodiment of the invention, a simulation model of each component of the circuit breaker and the circuit breaker as a whole can be established based on the internal physical structure of the circuit breaker using finite element analysis software, and then finite element simulation can be performed. The finite element analysis software includes, but is not limited to, COMSOL software. As an optional embodiment of the invention, finite element simulation is performed on each component of the circuit breaker except for the closing resistor to obtain the electrical characteristics of each component. This includes: establishing a simulation model of the closing resistor of the circuit breaker and the tank containing each component except for the closing resistor; using the steady-state electromagnetic field in the finite element analysis software to perform finite element simulation on the simulation model to obtain the first potential and first electric field of each component of the circuit breaker except for the closing resistor, and the electrical characteristics including the first potential and the first electric field.

[0023] Specifically, this embodiment of the invention first analyzes the components of the circuit breaker, then determines the dimensions, parameters, and materials used for each component. For example, the dimensional parameters of each component are as follows: Closing resistor: cylinder (diameter φ25mm × 100mm); Input side bushing / output side bushing: coaxial cylinder (inner conductor φ20mm, outer insulation φ100mm, length 500mm); Main contact: frustum contact (φ50mm, spacing 10-30mm adjustable); Auxiliary contact: disc electrode (φ80mm, spacing 5mm); Shielding cover: hemispherical (φ200mm, thickness 5mm); Tank: cylindrical (φ600mm × 1200mm). The material configuration of each component is as follows: Components using copper / aluminum in the circuit breaker: conductivity 5.96e7S / m, relative permeability 1. SF6 gas in the circuit breaker: relative permittivity 1.002, breakdown field strength 30kV / mm. Components in the circuit breaker containing epoxy resin: relative permittivity 4.5, conductivity 1e-14S / m. Steel tank in the circuit breaker: conductivity 1e6S / m, relative permeability 100.

[0024] Furthermore, after determining the dimensional parameters and materials of the aforementioned components in the circuit breaker, the circuit breaker is simulated using COMSOL software based on the actual connection relationships and physical structure of the internal components, resulting in a simulation model of the circuit breaker.

[0025] Furthermore, in this embodiment of the invention, the physical field in the COMSOL software is set to a steady-state electromagnetic field, i.e., an electrostatic field. Then, the steady-state electromagnetic field in COMSOL software is used to perform finite element simulation on the simulation model. Specifically, the equalizing capacitor and auxiliary break in the simulation model are simulated separately. Specifically, an excitation signal is applied to both ends of the equalizing capacitor or auxiliary break in the simulation model. This excitation signal is consistent with the actual operating state of the circuit breaker, obtaining the first potential and first electric field of the equalizing capacitor or auxiliary break. The shielding cover and central casting in the simulation model are simulated as a whole using the simulation model. Specifically, an excitation signal is applied to the input-side bushing and output-side bushing of the simulation model. This excitation signal is the same as the actual operating state of the circuit breaker, obtaining the first potential and first electric field of the shielding cover and central casting relative to the tank in the circuit breaker. The electrical characteristics include the first potential and first electric field. It is worth noting that the relevant technologies of COMSOL software can be found in existing technologies, and will not be elaborated further in this embodiment of the invention.

[0026] Furthermore, as an optional embodiment of the present invention, calculating the circuit element parameters of each component of the circuit breaker based on the electrical characteristics of the components other than the closing resistor includes: equipping the remaining components of the circuit breaker, excluding the closing resistor, with equivalent capacitor elements, resistor elements, and inductor elements in series and in parallel, based on their operating characteristics; calculating the capacitance value of the equivalent capacitor elements, the resistance value of the resistor elements, and the inductance value of the inductor elements based on the first potential and the first electric field in the electrical characteristics; connecting the test closing resistor, capacitor elements, resistor elements, and inductor elements in series and in parallel according to the actual connection relationship of each component of the circuit breaker, and assigning corresponding capacitance, resistance, and inductance values ​​to each capacitor element, resistor element, and inductor element in series and inductor element in parallel, thus obtaining a simulation system of the circuit breaker.

[0027] Specifically, the steady-state electromagnetic field includes electrostatic and magnetic fields. In this embodiment of the invention, when calculating the equivalent capacitance value, the physical field is the electrostatic field. When applying excitation voltage to each component in the analog circuit, COMSOL solves for physical quantities such as electric field distribution (e.g., charge distribution) and electric potential based on boundary conditions and Maxwell's equations. Then, it calculates the capacitance value using the formula Q = C·V. Here, Q represents the charge distribution in the first electric field, V represents the applied voltage (i.e., electric potential), and C represents the capacitance.

[0028] Furthermore, when calculating the inductance, the steady-state electromagnetic fields are selected as magnetic and electric fields, and the analysis is performed in the frequency domain. In this embodiment of the invention, COMSOL software is used to create a space representing air or SF6 gas around the simulation model, with the outer boundary defaulting to magnetic and electrical insulation. In this embodiment of the invention, boundary conditions are set at both ends of the simulated component in the simulation model; one end is grounded, and the other end has an applied potential. This terminal generates an admittance variable for the inductor, according to... The inductance of each component in the simulation model is calculated, where ω is the angular frequency, Y11 is the terminal admittance, and the effective conductivity caused by resistive and magnetic losses in the component is used as the real part of Y11. Furthermore, to construct a model that satisfies the conditions for each component in the simulation model, this embodiment of the invention defines Ampere's law and current conservation for some domains and selects magnetic loss in the constitutive relation BH for the remaining components. By defining the preconditions of Ampere's law, current conservation, and constitutive relation BH, the modeling of the actual situation is completed. The model of the finite loss magnetic core is as follows: Where B is the magnetic field strength, dl is the differential length element of the integral along the closed path, and I enc Let μ0 be the total current at interface S defined by a right-hand closed path, and μ0 be the free permeability. The relationship between current density and charge density is: Where J is the current density and ρ is the charge density. The BH curve describes the relationship between the magnetic field strength H and the magnetic flux strength B. If the permeability of the medium is anisotropic, then since B = μH, where μ represents the permeability of the medium, B and H may not be consistent. If the permeability of the medium is isotropic, B and H are always consistent.

[0029] Furthermore, when calculating resistance, a potential difference is applied to the component, and a current is generated in the electric field. The current intensity is a function of the applied potential difference, and the current is proportional to the potential difference. The ratio of the potential difference across the resistor to the current generated in the first electric field is the resistance value.

[0030] Furthermore, in this embodiment of the invention, by collecting historical damage types and degrees of various types of circuit breakers, different degrees of damage are artificially set for undamaged closing resistors based on the historical damage types and degrees, such as common fault types like resistance value deviation from rated value, poor contact, local overheating and aging, and insulation layer damage, and different degrees of damage are set to cover various damage scenarios that may occur in the actual operation of the circuit breaker. Then, the obtained test closing resistor is connected to the simulation system.

[0031] Step S202: Connect each circuit element and the test closing resistor according to the actual connection relationship of each component in the circuit breaker to obtain a simulation system with a mixed connection of circuit elements and actual closing resistor, so as to realize the equivalent simulation of the electrical performance of the circuit breaker under the condition of closing damage.

[0032] Specifically, in this embodiment of the invention, the electrical characteristics of all components except the closing resistor are used to perform circuit equivalence on the various components of the circuit breaker. Each component in the circuit breaker is equivalent to a circuit element in a simulated system, and then these circuit elements are connected according to the actual connection relationships of the components in the circuit breaker to form a simulated system of the circuit breaker. When detecting damage to the closing resistor of the circuit breaker, testing can be directly performed on the simulated system using detection devices.

[0033] Furthermore, this embodiment of the invention considers the influence of the tank on each component during circuit breaker operation, namely the capacitance of each component to ground. Based on the first potential and first electric field of each component to ground in the simulation results, the capacitance values ​​of each component to ground in the circuit breaker, excluding the closing resistor, are calculated and presented in the form of capacitance. In addition, in the simulation circuit, this embodiment of the invention also fabricates two aluminum sheets with the same area as the closing resistor in the circuit breaker as electrodes to simulate the plates connected to the closing resistor in the actual circuit breaker. These aluminum sheets are respectively connected to both ends of the closing resistor, so that the current flows more uniformly through the closing resistor.

[0034] Furthermore, as an optional embodiment of the present invention, the circuit elements and the test closing resistor are connected according to the actual connection relationship of each component in the circuit breaker. The connection method includes: placing aluminum pads with the same cross-sectional area as the closing resistor at both ends of the closing resistor, and using springs to press the closing resistor. If necessary, a rubber ring is used to cover the damaged resistor piece to ensure good contact between each closing resistor and the aluminum pads. The uniform input and output of the sinusoidal sweep frequency signal is achieved through the external leads of the aluminum pads. Based on the actual installation position of each component in the circuit breaker, equivalent circuit elements and closing resistors are arranged. The circuit elements are placed in the circuit board, and the distance between each circuit board is adjusted proportionally according to the ratio of the test closing resistor to the actual closing resistor. It is also ensured that the connecting lines between each component are not easily moved to avoid the influence of component position changes on the test results.

[0035] Furthermore, as an optional embodiment of the present invention, after performing finite element simulation on each component in the simulation model except for the closing resistor using the steady-state electromagnetic field in the finite element analysis software to obtain the first potential and first electric field of each component in the circuit breaker except for the closing resistor, the method further includes: performing finite element simulation on the simulation system using the steady-state electromagnetic field in the finite element calculation software to obtain the second potential and second electric field of each system component in the simulation system except for the closing resistor; and verifying the effectiveness of the simulation system based on the second potential, second electric field, first potential, and first electric field.

[0036] Specifically, in this embodiment of the invention, a finite element simulation is performed on the simulation model to obtain the first potential and first electric field of each component in the circuit breaker, excluding the closing resistor. Then, the same simulation is performed on the equivalent simulation system to obtain the second potential and second electric field of each circuit element in the equivalent simulation system, excluding the closing resistor. The first and second potentials, and the first and second electric fields are then compared to verify the effectiveness of the equivalent simulation system. If there is a significant difference in the distribution between the first and second potentials or the first and second electric fields, it indicates that the equivalent simulation system does not closely approximate a real circuit breaker. The values ​​or connection methods of each circuit element in the simulation system need to be adjusted to more closely resemble an actual circuit breaker. The damage condition of the closing resistor can also be made closer to the actual damage condition of the closing resistor in a circuit breaker.

[0037] This invention utilizes finite element simulation to obtain the electric and magnetic field distributions of each component, transforming the complex structure of the circuit breaker into an equivalent simulation system containing parasitic parameters. This allows for a more accurate reflection of the circuit breaker's high-frequency characteristics (such as the location of the resonant point). Furthermore, parameters affecting the detection of closing resistance damage (such as the contact resistance of the main break, and the parasitic inductance of the input and output bushings) are refined and equivalent, improving the sensitivity of closing resistance damage detection. Furthermore, by leveraging the resonant characteristics of the RLC network, minute changes in closing resistance are converted into resonant point shifts in the sweep frequency curve, facilitating early fault identification of the closing resistance. Moreover, the simulation system provided in this invention allows for the study of the sweep frequency impedance curve under closing resistance damage conditions. This eliminates the need for manual disassembly and testing of the entire circuit breaker on-site; inferences can be made simply by sweeping the simulation system, saving significant manpower and resources and improving the efficiency of studying the sweep frequency impedance curve under closing resistance damage conditions. This avoids interference with the stable operation of the power system, significantly improving its stability and reliability.

[0038] Step S203: Obtain the impedance amplitude of the analog system under the sinusoidal sweep signal, and plot the sweep impedance curve of the analog circuit based on the impedance amplitude of the analog system under the sinusoidal sweep signal.

[0039] Specifically, obtaining the impedance amplitude of the analog system under a sinusoidal sweep signal includes: outputting a sinusoidal sweep signal to a power amplifier via a signal generator; amplifying the sinusoidal sweep signal and inputting it to the analog system; transmitting the sinusoidal sweep signal within the analog system and then outputting it to a shunt; determining the impedance amplitude of the analog system under the sinusoidal sweep signal based on the output signals of the power amplifier and the shunt; and then plotting a sweep impedance curve with frequency on the x-axis and impedance amplitude on the y-axis.

[0040] Furthermore, as an optional embodiment of the present invention, determining the impedance amplitude of the analog system under a sinusoidal sweep signal based on the output signal of the power amplifier and the output signal of the shunt includes: determining the ratio between the output signal of the power amplifier and the resistance value of the shunt, which is an expression for the input current signal of the shunt; extracting the first voltage amplitude and first phase of the output signal of the power amplifier and the second voltage amplitude and second phase of the output signal of the shunt; and determining the impedance amplitude of the circuit breaker's analog system under a sinusoidal sweep signal based on the expression for the input current signal of the shunt, the first voltage amplitude and first phase of the power amplifier, and the second voltage amplitude and second phase of the output signal of the shunt.

[0041] Specifically, in this embodiment of the invention, the signal acquisition device acquires voltage signals from both the power amplifier and the shunt. In this embodiment, the output signal of the power amplifier is denoted as... The output signal of the shunt is denoted as Where j is the imaginary unit, and ω is the angular frequency of the applied signal in rad / s. The expression for the input current signal of the shunt is then determined as follows:

[0042]

[0043] In the above formula, This represents the input current signal of the shunt, i.e., the current signal flowing through the analog system of the circuit breaker. This represents the output signal of the shunt. R1 represents the resistance value of the shunt.

[0044] Furthermore, in this embodiment of the invention, the expression for the input current signal of the shunt is substituted into the impedance calculation formula of the analog system:

[0045]

[0046] In the above formula, This represents the impedance of the simulated system. This indicates the output signal of the shunt. This represents the output signal of the power amplifier. This represents the input current signal of the shunt.

[0047] Furthermore, the expression for the input current signal of the shunt is... Substitution From this, we obtain the following formula:

[0048]

[0049] In the above formula, This represents the impedance of the simulated system. This indicates the output signal of the shunt. This represents the output signal of the power amplifier. R1 represents the resistance value of the shunt.

[0050] Furthermore, the formula The first voltage amplitude and first phase in the output signal of the power amplifier, and the second voltage amplitude and second phase in the output signal of the shunt are expressed as follows:

[0051]

[0052] In the above formula, This represents the impedance of the simulated system. This indicates the output signal of the shunt. This represents the output signal of the power amplifier. R1 represents the resistance value of the shunt. θ i θ represents the first phase of the output signal of the power amplifier. o This represents the second phase of the shunt's output signal. This represents the ratio between the first voltage amplitude in the output signal of the power amplifier and the second voltage amplitude in the output signal of the shunt.

[0053] Furthermore, the impedance of the above-mentioned simulated system is converted into impedance magnitude, and the specific calculation formula is as follows:

[0054]

[0055] In the above formula, Z k (jω) represents the impedance magnitude of the simulated system. θ=(θ i -θ o R1 represents the phase difference between the first and second phases. R1 represents the resistance value of the shunt. This indicates the output signal of the shunt. This represents the output signal of the power amplifier.

[0056] Step S204: Based on the swept frequency impedance curves of the simulated system under different damage conditions, the impedance characteristics of the circuit breaker under damage conditions are studied using the test closing resistance of the circuit breaker.

[0057] Specifically, in this embodiment of the invention, the swept frequency impedance curve of the simulated system of the circuit breaker under different damage types is compared with the standard swept frequency impedance curve of the circuit breaker when it is undamaged. If the closing resistor string in the circuit breaker is blackened and burned, the frequency of the resonant point of the swept frequency impedance curve of the simulated system of the damaged circuit breaker is smaller than that of the standard swept frequency impedance curve, and the impedance amplitude of the resonant point is larger.

[0058] If the closing resistor string in the circuit breaker is damaged by a crack, the frequency of the sweep frequency impedance curve of the simulated system of the damaged circuit breaker will be smaller than that of the standard sweep frequency impedance curve, and the impedance amplitude at the resonant point will be smaller.

[0059] If the closing resistor string in the circuit breaker experiences edge drop damage, the frequency of the sweep frequency impedance curve of the simulated system of the damaged circuit breaker will be smaller than that of the standard sweep frequency impedance curve, and the impedance amplitude at the resonant point will also be smaller. The degree of frequency and impedance amplitude reduction is more significant than the degree of reduction caused by the overall crack damage.

[0060] The swept frequency impedance curves of the simulated system of the circuit breaker under different damage levels are compared with the standard swept frequency impedance curve of the circuit breaker when it is undamaged. If the closing resistor string in the circuit breaker is slightly damaged, and the number or volume of the damaged indicator resistor exceeds 1 / 30 of the total number or volume of the closing resistor string, then the impedance amplitude of the swept frequency impedance curve of the simulated system of the damaged circuit breaker changes by more than 5% compared with the impedance amplitude at the resonant point of the standard swept frequency impedance curve.

[0061] If the closing resistor string in the circuit breaker is moderately damaged, and the number or volume of damaged indicator resistors exceeds 1 / 20 of the total number or volume of the closing resistor string, then the impedance amplitude of the swept frequency impedance curve of the circuit breaker's simulation system under damage will change by more than 10% compared to the impedance amplitude at the resonant point of the standard swept frequency impedance curve.

[0062] If the closing resistor string in the circuit breaker is severely damaged, and the number or volume of damaged indicator resistors exceeds 1 / 10 of the total number or volume of the closing resistor string, then the impedance amplitude of the swept frequency impedance curve of the circuit breaker's simulation system under damage will change by more than 20% compared to the impedance amplitude at the resonant point of the standard swept frequency impedance curve.

[0063] Furthermore, as an optional embodiment of the present invention, the simulation test method further includes: storing the swept frequency impedance curves of the simulated system of the test closing resistor of the circuit breaker under different damage conditions in a database to obtain a comparison database; and detecting the damage condition of the closing resistor in the actual scenario of the circuit breaker based on the swept frequency impedance curves of the simulated system of the test closing resistor under different damage conditions in the comparison database.

[0064] Specifically, in the simulation system, a swept-frequency impedance test is performed on the test closing resistor under each damage condition. During the test, parameters such as the swept-frequency range, frequency interval, and signal strength need to be precisely controlled to ensure the accuracy and consistency of the test data. Impedance values ​​at different frequency points are collected using impedance testing equipment to generate complete swept-frequency impedance curves. Each swept-frequency impedance curve needs to be associated and labeled with corresponding damage type, damage degree, and other information to form raw data containing multi-dimensional information.

[0065] Then, all collected sweep frequency impedance curves and related information are organized and stored in a database according to a standardized data format, constructing a comparison database of sweep frequency impedance curves under different damage conditions of the test closing resistor. Based on the constructed comparison database, the damage condition of the closing resistor in actual circuit breaker scenarios can be detected. In the actual testing process, the operating closing resistor is subjected to sweep frequency impedance testing using on-site testing equipment to obtain the actual sweep frequency impedance curve. The actual sweep frequency impedance curve is input into the testing system, and the system automatically compares and analyzes it with the reference sweep frequency impedance curves under various damage conditions in the comparison database. The comparison analysis process can use a curve matching algorithm to calculate the similarity, characteristic parameter deviation, and other indicators between the actual sweep frequency impedance curve and the reference sweep frequency impedance curve. According to the preset judgment rules, when the actual sweep frequency impedance curve and the reference sweep frequency impedance curve under a certain damage condition reach a certain degree of matching, and the characteristic parameter deviation is within the set threshold range, it can be determined that the closing resistor has a corresponding damage type and damage degree. This method enables rapid and accurate identification of damage to the closing resistor, providing a scientific basis for circuit breaker maintenance and repair, effectively preventing circuit breaker malfunctions caused by closing resistor faults, and ensuring the safe and stable operation of the power system.

[0066] This invention, through precise circuit equivalent calculations of all components of a circuit breaker except the closing resistor, and replacing the equivalent components with actual circuit elements, can maximally restore the true internal circuit structure and electrical connections of the circuit breaker. By constructing a hybrid connection simulation system based on the test closing resistor determined from historical damage conditions, high-fidelity electrical performance simulations of circuit breaker operation under different damage types and degrees can be achieved. This provides a test platform close to actual operating conditions for subsequent impedance characteristic studies, effectively avoiding research deviations caused by simulation distortion. Furthermore, this invention eliminates the need to disassemble numerous operating or decommissioned circuit breakers; various damage scenarios can be reproduced through circuit equivalent calculations and simulation system construction, significantly reducing manpower and material costs and shortening the test preparation cycle. Simultaneously, the simulation system allows for flexible adjustment of damage parameters and test conditions in a laboratory environment, facilitating systematic and repetitive frequency sweep tests and data analysis. This effectively solves operational challenges such as site limitations and equipment integrity disruptions in field studies, greatly improving the efficiency and feasibility of studying the impedance characteristics of circuit breakers. By simulating impedance amplitude tests and plotting sweep impedance curves under sinusoidal sweep signals at different frequencies, subtle impedance changes caused by closing resistor damage can be captured from multiple frequency band dimensions. Analysis of the sweep impedance curves under different damage conditions allows for in-depth exploration of the intrinsic correlation between damage type, damage degree, and impedance characteristics. This provides a quantitative basis for accurately identifying the damage state of the closing resistor, helps establish a more scientific damage assessment model, and significantly improves the depth and accuracy of circuit breaker impedance characteristic research.

[0067] Based on the same inventive concept, such as Figure 3 As shown, Figure 3 This is a schematic diagram of a simulation system for detecting damage to the closing resistor of a circuit breaker, provided by an embodiment of the present invention. The simulation system includes: a series branch, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first parallel branch, and a second parallel branch. The series branch is formed by connecting a first resistor, a first inductor, and the closing resistor in series. The first parallel branch is formed by connecting a second resistor and a fifth capacitor in parallel. The second parallel branch is formed by connecting a third resistor and a sixth capacitor in parallel. The first parallel branch is the equivalent circuit of the input bushing of the circuit breaker, and the second parallel branch is the equivalent circuit of the output bushing of the circuit breaker. The first resistor and the first inductor are auxiliary breaks of the circuit breaker. The equivalent circuit elements are as follows: the first capacitor is the equivalent circuit element of the main break of the circuit breaker; the second capacitor is the equivalent circuit element of the voltage equalizing capacitor of the circuit breaker; the third capacitor is the equivalent circuit element of the shielding cover; and the fourth capacitor is the equivalent capacitor element of the central casting. The output terminal of the first parallel branch is connected to the first capacitor, the second capacitor, the third capacitor, and one end of the series branch, respectively. The other end of the third capacitor is grounded. The input terminal of the second parallel branch is connected to the first capacitor, the second capacitor, the third capacitor, and the other end of the series branch, respectively. One end of the fourth capacitor is connected to the series branch, the first capacitor, and the second capacitor, respectively. The other end of the fourth capacitor is grounded.

[0068] Specifically, Figure 3 It is based on Figure 1 The simulation results of the internal structure of the circuit breaker shown are equivalent. Figure 3 In this circuit, C1 and C2 serve as the second capacitor, forming the equivalent circuit of the voltage equalization capacitor. C3 and C4 serve as the first capacitor, forming the equivalent circuit of the main break. C5 and C6 serve as the third capacitor, forming the ground capacitance of the shield. C7 serves as the fourth capacitor, forming the ground capacitance of the central casting. The resistive-inductive circuit forming a series branch with the closing resistor is the equivalent circuit of the auxiliary break, namely the first resistor R1 and the first inductor L1. The parallel RC circuit connecting the left and right breaks is the equivalent circuit of the input bushing, i.e., the first parallel branch, and the equivalent circuit of the output bushing, i.e., the second parallel branch. The first parallel branch is formed by the second resistor R2 and the fifth capacitor C8 connected in parallel. The second parallel branch is formed by the third resistor R3 and the sixth capacitor C9 connected in parallel.

[0069] Furthermore, the simulation circuit in this embodiment of the invention may also include two aluminum sheets with the same area as the closing resistor in the circuit breaker as electrodes to simulate the plates connected to the closing resistor in an actual circuit breaker. These aluminum sheets are connected to both ends of the closing resistor, making the current flow through the closing resistor more uniform. This improves the accuracy of the detection results for damage to the closing resistor.

[0070] The simulation system described in this embodiment of the invention is a circuit equivalent to the actual structure of a circuit breaker. It reflects the actual operating state of the circuit breaker and refines the parameters affecting the detection of closing resistance damage (such as the contact resistance of the main break, the parasitic inductance of the input bushing, and the output bushing), thereby improving the sensitivity of the circuit breaker's closing resistance damage detection. Furthermore, by utilizing the resonant characteristics of the RLC network, minute changes in the closing resistance are converted into a shift in the resonant point of the frequency sweep curve, facilitating early fault identification of the closing resistance. Moreover, by using the simulation circuit provided in this embodiment of the invention to detect the damage to the closing resistance, there is no need for on-site manual disassembly and inspection of the entire circuit breaker. The impedance frequency sweep curve pattern under the damaged state of the closing resistance can be inferred by performing frequency sweep tests on the simulation system, saving significant manpower and resources, avoiding interference with the stable operation of the power system, and significantly improving the stability and reliability of the power system operation.

[0071] Based on the same inventive concept, such as Figure 4 The diagram shown illustrates a simulation test system for studying the impedance characteristics of a circuit breaker under conditions of closing resistance damage, provided by an embodiment of the present invention. This simulation test system includes: the components described in the above embodiment. Figure 3 The analog system, signal generator, power amplifier, shunt, signal acquisition device, and electronic equipment mentioned herein; the signal generator is connected to the input of the power amplifier, the output of the power amplifier is connected to the input of the first parallel branch in the analog system and the signal acquisition device, the output of the second parallel branch in the analog system is connected to the input of the shunt, the output of the shunt is connected to the signal acquisition device, and the signal acquisition device is also connected to the electronic equipment; the signal generator is used to output a sinusoidal sweep frequency signal to the power amplifier, and the sinusoidal sweep frequency signal is amplified by the power amplifier and then transmitted through the input of the first parallel branch and the second parallel branch in the analog system. The circuit breaker outputs signals from the power amplifier, the shunt input, and the shunt output. Signal acquisition equipment is used to acquire the output signals of the power amplifier and the shunt, and to process these signals to obtain the impedance amplitude of the circuit breaker's analog system under a sinusoidal sweep signal. Electronic equipment is used to plot the sweep impedance curve of the circuit breaker's analog system based on the impedance amplitude of the analog system under a sinusoidal sweep signal. Furthermore, based on the sweep impedance curve of the analog system under different damage conditions, the impedance characteristics of the circuit breaker's test closing resistance under damage conditions are studied.

[0072] Specifically, in this embodiment of the invention, after obtaining the simulation system, a test system for detecting damage to the closing resistance of a circuit breaker is constructed, sequentially connecting a signal generator, a power amplifier, a shunt, a signal acquisition device, and electronic equipment. The signal generator applies a series of continuously varying, wide-bandwidth sinusoidal sweep signals to the simulation system. Since the signal output from the signal generator is input to the power amplifier, and the power amplifier has certain limitations on the amplitude of the input signal, this embodiment of the invention determines the signal amplitude of the sinusoidal sweep signal based on the input limitations of the power amplifier, ensuring the stability and accuracy of the sinusoidal sweep signal output by the signal generator. Further, the power amplifier is set to a constant current, voltage amplification mode. Then, the amplification factor of the power amplifier for the sinusoidal sweep signal is adjusted according to the output limitations of the power amplifier. The amplified signal output value from the power amplifier is then processed by the signal acquisition device and the equivalent circuit (first parallel branch) of the input bushing in the simulation system. The signal flowing through the simulation system is input to the shunt via the equivalent circuit (second parallel branch) of the output bushing in the simulation system. The shunt converts the current signal into a voltage signal and outputs it to the signal acquisition device. The signal acquisition equipment collects and processes the output signals of the power amplifier and the shunt at different frequencies to obtain the impedance amplitude of the overall analog system under a sinusoidal sweep signal. The signal acquisition equipment outputs the impedance amplitude under the sinusoidal sweep signal to the electronic equipment, which plots the sweep impedance curve of the analog system with frequency on the horizontal axis and impedance amplitude on the vertical axis. This sweep impedance curve reflects the impedance characteristics of the analog system at different frequencies, and its shape and characteristic points contain information about the operating status of each component inside the circuit breaker.

[0073] Furthermore, the electronic device can be a computer with computing capabilities. The signal acquisition device can be a data acquisition card.

[0074] Furthermore, as an optional embodiment of the present invention, the signal acquisition device processes the output signal of the power amplifier and the output signal of the shunt to obtain the impedance amplitude of the circuit breaker's analog system under a sinusoidal sweep signal, including: determining the ratio between the output signal of the power amplifier and the resistance value of the shunt, which is an expression for the input current signal of the shunt; extracting the first voltage amplitude and first phase of the output signal of the power amplifier and the second voltage amplitude and second phase of the output signal of the shunt; and determining the impedance amplitude of the circuit breaker's analog system under a sinusoidal sweep signal based on the expression for the input current signal of the shunt, the first voltage amplitude and first phase in the output signal of the power amplifier, and the second voltage amplitude and second phase in the output signal of the shunt.

[0075] Specifically, in this embodiment of the invention, the signal acquisition device acquires voltage signals from both the power amplifier and the shunt. In this embodiment, the output signal of the power amplifier is denoted as... The output signal of the shunt is denoted as Where j is the imaginary unit, and ω is the angular frequency of the applied signal in rad / s. The expression for the input current signal of the shunt is then determined as follows:

[0076]

[0077] In the above formula, This represents the input current signal of the shunt, i.e., the current signal flowing through the analog system of the circuit breaker. This represents the output signal of the shunt. R1 represents the resistance value of the shunt.

[0078] Furthermore, in this embodiment of the invention, the expression for the input current signal of the shunt is substituted into the impedance calculation formula of the analog system:

[0079]

[0080] In the above formula, This represents the impedance of the simulated system. This indicates the output signal of the shunt. This represents the output signal of the power amplifier. This represents the input current signal of the shunt.

[0081] Furthermore, the expression for the input current signal of the shunt is... Substitution From this, we obtain the following formula:

[0082]

[0083] In the above formula, This represents the impedance of the simulated system. This indicates the output signal of the shunt. This represents the output signal of the power amplifier. R1 represents the resistance value of the shunt.

[0084] Furthermore, the formula The first voltage amplitude and first phase in the output signal of the power amplifier, and the second voltage amplitude and second phase in the output signal of the shunt are expressed as follows:

[0085]

[0086] In the above formula, This represents the impedance of the simulated system. This indicates the output signal of the shunt. This represents the output signal of the power amplifier. R1 represents the resistance value of the shunt. θ i θ represents the first phase of the output signal of the power amplifier. o This represents the second phase of the shunt's output signal. This represents the ratio between the first voltage amplitude in the output signal of the power amplifier and the second voltage amplitude in the output signal of the shunt.

[0087] Furthermore, the impedance of the above-mentioned simulated system is converted into impedance magnitude, and the specific calculation formula is as follows:

[0088]

[0089] In the above formula, Z k (jω) represents the impedance magnitude of the simulated system. θ=(θ i -θ o R1 represents the phase difference between the first and second phases. R1 represents the resistance value of the shunt. This indicates the output signal of the shunt. This represents the output signal of the power amplifier.

[0090] Furthermore, specifically, in this embodiment of the invention, the swept frequency impedance curve of the simulated system of the circuit breaker under different damage types is compared with the standard swept frequency impedance curve of the circuit breaker when it is undamaged. If the closing resistor string in the circuit breaker is blackened and burned, the frequency of the resonant point of the swept frequency impedance curve of the simulated system of the damaged circuit breaker is smaller than that of the standard swept frequency impedance curve, and the impedance amplitude at the resonant point is larger.

[0091] If the closing resistor string in the circuit breaker is damaged by a crack, the frequency of the sweep frequency impedance curve of the simulated system of the damaged circuit breaker will be smaller than that of the standard sweep frequency impedance curve, and the impedance amplitude at the resonant point will be smaller.

[0092] If the closing resistor string in the circuit breaker experiences edge drop damage, the frequency of the sweep frequency impedance curve of the simulated system of the damaged circuit breaker will be smaller than that of the standard sweep frequency impedance curve, and the impedance amplitude at the resonant point will also be smaller. The degree of frequency and impedance amplitude reduction is more significant than the degree of reduction caused by the overall crack damage.

[0093] The swept frequency impedance curves of the simulated system of the circuit breaker under different damage levels are compared with the standard swept frequency impedance curve of the circuit breaker when it is undamaged. If the closing resistor string in the circuit breaker is slightly damaged, and the number or volume of the damaged indicator resistor exceeds 1 / 30 of the total number or volume of the closing resistor string, then the impedance amplitude of the swept frequency impedance curve of the simulated system of the damaged circuit breaker changes by more than 5% compared with the impedance amplitude at the resonant point of the standard swept frequency impedance curve.

[0094] If the closing resistor string in the circuit breaker is moderately damaged, and the number or volume of damaged indicator resistors exceeds 1 / 20 of the total number or volume of the closing resistor string, then the impedance amplitude of the swept frequency impedance curve of the circuit breaker's simulation system under damage will change by more than 10% compared to the impedance amplitude at the resonant point of the standard swept frequency impedance curve.

[0095] If the closing resistor string in the circuit breaker is severely damaged, and the number or volume of damaged indicator resistors exceeds 1 / 10 of the total number or volume of the closing resistor string, then the impedance amplitude of the swept frequency impedance curve of the circuit breaker's simulation system under damage will change by more than 20% compared to the impedance amplitude at the resonant point of the standard swept frequency impedance curve.

[0096] It should be noted that the simulation test method and system provided in this embodiment of the invention for studying the impedance characteristics of circuit breakers under the condition of closing resistance damage are based on the same application concept. Therefore, the same or similar parts between the various embodiments can be referred to each other and have the same or similar beneficial effects. The embodiments of the invention will not repeat the repeated parts.

[0097] For example, to further illustrate the embodiments of the present invention, the embodiments of the present invention provide the following experimental scenarios, such as... Figure 5 As shown, Figure 5 This invention provides swept-frequency impedance curves under conditions of damaged and undamaged closing resistors, as provided in an embodiment of the invention. Figure 5 In the diagram, curve 1 represents the closing resistor with slight edge damage, while curve 2 represents the closing resistor without damage. The resonant frequency of curve 1 is 881kHz, and the resonant impedance is 263.033Ω. The resonant frequency of curve 2 is 896kHz, and the resonant impedance is 280.542Ω. Comparing curves 1 and 2 in this embodiment, curve 1 shows a slight overall shift compared to curve 2. Under the influence of a high-frequency sinusoidal signal, the resonant frequency of curve 1 decreases by 15kHz, a change not exceeding 5% of the resonant frequency of curve 2 in the undamaged state. The impedance of the resonant point of curve 1 decreases by 17.509Ω, a change exceeding 5% of the resonant impedance of curve 2 in the undamaged state, but not exceeding 10%. Therefore, through... Figure 5 It can be verified that if the closing resistor string in the circuit breaker is damaged by edge drop, the frequency of the sweep frequency impedance curve of the simulated system of the damaged circuit breaker will be smaller than that of the standard sweep frequency impedance curve, and the impedance amplitude at the resonant point will be smaller.

[0098] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0099] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A simulation test method for researching the impedance characteristic law of circuit breaker under the condition of closing resistance damage, characterized in that, The method comprises the following steps: carrying out circuit equivalent calculation on the rest of the components in the circuit breaker except the closing resistor to obtain the equivalent circuit element parameters of the rest of the components in the circuit breaker, and using actual circuit elements corresponding to the equivalent circuit element parameters to replace the rest of the components in the circuit breaker; determining the test closing resistor based on the historical damage condition of the closing resistor of the circuit breaker; connecting each of the circuit elements and the test closing resistor according to the actual connection relationship of each component in the circuit breaker to obtain a simulation system in which circuit elements and actual closing resistors are connected, and realizing equivalent simulation of the electrical performance of the circuit breaker under the closing damage condition; obtaining the impedance amplitude of the simulation system under the sinusoidal sweep signal, and drawing the sweep impedance curve of the simulation circuit based on the impedance amplitude of the simulation system under the sinusoidal sweep signal; based on the sweep impedance curve of the simulation system of the test closing resistor of the circuit breaker under different damage conditions, researching the impedance characteristic law of the circuit breaker under the damage condition of the test closing resistor of the circuit breaker.

2. The simulation test method according to claim 1, characterized by, The simulation test method further comprises: storing the sweep impedance curve of the simulation system of the test closing resistor of the circuit breaker under different damage conditions in the comparative database to obtain a comparison database; based on the sweep impedance curve of the simulation system of the test closing resistor in the comparative database under different damage conditions, detecting the damage condition of the closing resistor in the actual scene of the circuit breaker.

3. The simulation test method according to claim 1, characterized by, The circuit breaker comprises a closing resistor, an input side bushing, an output side bushing, a shield, a main break, an auxiliary break, a voltage equalizing capacitor and a center casting. The circuit equivalent calculation is carried out on the rest of the components in the circuit breaker except the closing resistor to obtain the equivalent circuit element parameters of the rest of the components in the circuit breaker, which comprises the following steps: carrying out finite element simulation on the rest of the components in the circuit breaker except the closing resistor to obtain the electrical characteristics of the rest of the components in the circuit breaker; calculating the circuit element parameters of each component of the circuit breaker according to the electrical characteristics of the rest of the components except the closing resistor; wherein the auxiliary break is equivalent to a first resistor and a first inductor, the first resistor, the first inductor and the closing resistor are connected in series to form a series branch, the main break is equivalent to a first capacitor, the voltage equalizing capacitor is equivalent to a second capacitor, the first capacitor, the second capacitor and the series branch are connected in parallel, the shield is equivalent to a third capacitor, the center casting is equivalent to a fourth capacitor, the input side bushing is equivalent to a second resistor and a fifth capacitor, the second resistor and the fifth capacitor are connected in parallel, and the output side bushing is equivalent to a third resistor and a sixth capacitor, the third resistor and the sixth capacitor are connected in parallel; the finite element simulation on the rest of the components in the circuit breaker except the closing resistor to obtain the electrical characteristics of the rest of the components in the circuit breaker comprises the following steps: establishing a simulation model of each component of the circuit breaker except the closing resistor and the tank in which each component except the closing resistor is located; The steady-state electromagnetic field in the finite element analysis software is used to perform finite element simulation on each component in the simulation model except the closing resistor, to obtain the first electric potential and the first electric field of each component in the circuit breaker except the closing resistor, and the electrical characteristics include the first electric potential and the first electric field.

4. The simulation test method according to claim 3, characterized by, The calculation of the circuit element parameters of each component of the circuit breaker according to the electrical characteristics of the remaining components except the closing resistor includes: According to the working characteristics of the remaining components in the circuit breaker except the closing resistor, the remaining components are equivalent to a series branch of a capacitance element, a resistance element and an inductance element, and a parallel branch of a capacitance element and an inductance element; According to the first electric potential and the first electric field in the electrical characteristics, the capacitance value of the capacitance element, the resistance value of the resistance element and the inductance value of the inductance element after the remaining components of the circuit breaker except the closing resistor are equivalent are calculated; The test closing resistor, the capacitance element, the resistance element and the inductance element series branch, and the capacitance element and the inductance element parallel branch are connected according to the actual connection relationship of each component of the circuit breaker, and the corresponding capacitance value, resistance value and inductance value of each capacitance element, resistance element and inductance element series branch and capacitance element and inductance element parallel branch are assigned, to obtain the simulation system of the circuit breaker.

5. The simulation test method according to claim 3, characterized by, After the steady-state electromagnetic field in the finite element analysis software is used to perform finite element simulation on each component in the simulation model except the closing resistor, to obtain the first electric potential and the first electric field of each component in the circuit breaker except the closing resistor, the method further includes: The steady-state electromagnetic field in the finite element analysis software is used to perform finite element simulation on each component in the simulation model except the closing resistor, to obtain the first electric potential and the first electric field of each component in the circuit breaker except the closing resistor, and the electrical characteristics include the first electric potential and the first electric field. The steady-state electromagnetic field in the finite element analysis software is used to perform finite element simulation on each component in the simulation model except the closing resistor, to obtain the first electric potential and the first electric field of each component in the circuit breaker except the closing resistor, and the electrical characteristics include the first electric potential and the first electric field.

6. The simulation test method according to claim 1, characterized by, The connection mode includes: An aluminum pad with the same area as the cross section of the closing resistor is placed at both ends of the closing resistor, and the closing resistor is pressed by a spring, and the aluminum pad is connected to the lead wire to realize uniform input and output of the sinusoidal sweep signal; Based on the actual installation position of each component in the circuit breaker, the equivalent circuit elements and the closing resistor are arranged, the circuit elements are placed in the circuit board, the distance between each circuit board is adjusted in proportion to the size ratio change of the test closing resistor and the actual closing resistor, and the connection lines between each element are not easily moved.

7. The simulation test method according to claim 1, characterized by, The impedance amplitude of the simulation system under the sinusoidal sweep signal includes: The signal generator outputs a sinusoidal sweep signal to the power amplifier, the sinusoidal sweep signal is amplified by the power amplifier and input to the simulation system, and the sinusoidal sweep signal is transmitted in the simulation system and output to the shunt; Based on the output signal of the power amplifier and the output signal of the shunt, the impedance amplitude of the simulation system under the sinusoidal sweep signal is determined.

8. The simulation test method according to claim 7, characterized by, The determining the impedance amplitude of the analog system under the sinusoidal sweep signal based on the output signal of the power amplifier and the output signal of the shunt includes: determining the ratio between the output signal of the power amplifier and the resistance value of the shunt, which is the expression of the input current signal of the shunt; extracting the first voltage amplitude and the first phase of the output signal of the power amplifier and the second voltage amplitude and the second phase of the output signal of the shunt; determining the impedance amplitude of the analog system under the sinusoidal sweep signal according to the expression of the input current signal of the shunt, the first voltage amplitude and the first phase of the power amplifier, and the second voltage amplitude and the second phase in the output signal of the shunt.

9. The simulation test method according to claim 1, characterized by, The research on the impedance characteristics of the circuit breaker under the damage condition of the test closing resistance of the circuit breaker based on the sweep impedance curve of the analog system of the test closing resistance of the circuit breaker under different damage conditions includes: Comparing the sweep impedance curve of the analog system of the circuit breaker under different damage types with the standard sweep impedance curve of the circuit breaker when there is no damage, if the closing resistance string in the circuit breaker appears blackening and charring damage, the frequency of the curve resonance point of the sweep impedance curve of the analog system of the damaged circuit breaker compared with the standard sweep impedance curve will be smaller, and the impedance amplitude of the resonance point will be larger; If the closing resistance string in the circuit breaker appears whole crack damage, the frequency of the curve resonance point of the sweep impedance curve of the analog system of the damaged circuit breaker compared with the standard sweep impedance curve will be smaller, and the impedance amplitude of the resonance point will be smaller; If the closing resistance string in the circuit breaker appears edge drop damage, the frequency of the curve resonance point of the sweep impedance curve of the analog system of the damaged circuit breaker compared with the standard sweep impedance curve will be smaller, and the impedance amplitude of the resonance point will be smaller, wherein the degree of frequency decrease and the degree of impedance amplitude decrease are more obvious than those of the whole crack damage; Comparing the sweep impedance curve of the analog system of the circuit breaker under different damage degrees with the standard sweep impedance curve of the circuit breaker when there is no damage, if the closing resistance string in the circuit breaker appears slight damage, the slight damage indicates that the number or volume of damaged resistance pieces exceeds 1 / 30 of the total number or volume of the closing resistance string, the impedance amplitude of the curve resonance point of the sweep impedance curve of the damaged circuit breaker compared with the standard sweep impedance curve will change more than 5%; If the closing resistance string in the circuit breaker appears moderate damage, the moderate damage indicates that the number or volume of damaged resistance pieces exceeds 1 / 20 of the total number or volume of the closing resistance string, the impedance amplitude of the curve resonance point of the sweep impedance curve of the damaged circuit breaker compared with the standard sweep impedance curve will change more than 10%; If the closing resistance string in the circuit breaker appears severe damage, the severe damage indicates that the number or volume of damaged resistance pieces exceeds 1 / 10 of the total number or volume of the closing resistance string, the impedance amplitude of the curve resonance point of the sweep impedance curve of the damaged circuit breaker compared with the standard sweep impedance curve will change more than 20%.

10. A simulation test system for researching the impedance characteristics of circuit breakers under the condition of closing resistance damage, characterized in that, The simulation system comprises a circuit breaker, a signal generator, a power amplifier, a shunt, a signal acquisition device and an electronic device; the signal generator is connected with an input end of the power amplifier; an output end of the power amplifier is connected with an input end of a first parallel branch in the simulation system and the signal acquisition device respectively; an output end of a second parallel branch in the simulation system is connected with an input end of the shunt; an output end of the shunt is connected with the signal acquisition device; and the signal acquisition device is further connected with the electronic device; The signal generator is used for outputting a sinusoidal sweep signal to the power amplifier; the sinusoidal sweep signal is amplified by the power amplifier and then outputted through the input end of the first parallel branch, the output end of the second parallel branch, the input end of the shunt and the output end of the shunt in the simulation system; The signal acquisition device is used for acquiring and processing the output signals of the power amplifier and the shunt to obtain the impedance amplitude of the simulation system of the circuit breaker under the sinusoidal sweep signal; The electronic device is used for drawing the sweep impedance curve of the simulation system of the circuit breaker according to the impedance amplitude of the simulation system of the circuit breaker under the sinusoidal sweep signal, and researching the impedance characteristic law of the circuit breaker under the damage condition based on the sweep impedance curves of the simulation system of the test closing resistance of the circuit breaker under different damage conditions.

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