Circuit breaker fault early warning method and system based on digital twinning

Abstract

The invention provides a circuit breaker fault early warning method and system based on digital twinning, and relates to the technical field of power equipment detection.The circuit breaker fault early warning method comprises the steps that electrical parameters, mechanical data and real-time environment temperature data of a circuit breaker are collected, and a circuit breaker electrical equivalent circuit model and a mechanical model after temperature correction are established; the accuracy of the circuit model is verified through loss power, and the accuracy of the mechanical model is verified through inherent frequency. The simulation calculation results of the circuit model and the mechanical model are combined, three state variables of current, voltage and frequency are detected and compared with a dynamic threshold value to generate a fault judgment index, and the state variables having faults are judged by synthesizing the value of the fault judgment index. The method effectively improves the monitoring precision and response speed of the circuit breaker, and reduces the fault risk.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment detection, and in particular to a circuit breaker fault early warning method and system based on digital twins. Background Art

[0002] In the power system, circuit breakers are key protection and control devices, and the reliability of their performance directly affects the safe operation of the entire power system. Traditional circuit breaker maintenance strategies rely on periodic physical inspections and scheduled maintenance plans. This method is not only time-consuming and labor-intensive, but also difficult to reflect the immediate working status and potential fault conditions of the circuit breaker in real time. In addition, due to changes in the external environment, such as temperature and humidity, the electrical and mechanical properties of the circuit breaker change. These factors may cause the circuit breaker to degrade in performance or even fail. Therefore, there is an urgent need for a solution that can monitor the status of the circuit breaker in real time and provide fault warnings for the circuit breaker to improve the stability and reliability of the power system.

[0003] In the prior art, publication number CN114091296A discloses a fault warning method and device for a high-voltage DC circuit breaker, including: pre-establishing a fault case library and a state evaluation model, obtaining component parameters of the high-voltage DC circuit breaker, performing state evaluation and simulation on the components to generate component state evaluation data and component remaining life data, generating a fault warning result of the high-voltage DC circuit breaker according to the component state evaluation data and the component remaining life data, and helping operation and maintenance personnel to predict fault conditions in advance through a parameter database.

[0004] The main problems with the above method are: a fault case library is established in advance but the update of the fault case library is not mentioned, which may lead to the problem of delayed update of the fault case library and the lack of dynamic adjustment mechanism, resulting in insufficient flexibility in response to sudden faults or new fault modes; and, during the evaluation, only the component parameters of the high-voltage DC circuit breaker are focused on, while the external environment will also have a potential impact on the performance of the circuit breaker, resulting in incomplete fault warning and inaccurate judgment results.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a circuit breaker fault early warning method and system based on digital twins to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A circuit breaker fault early warning method based on digital twin, the specific steps include:

[0009] Step 1: Collect the electrical parameters and mechanical characteristics of the circuit breaker according to the technical manual, and collect the ambient temperature data in the operating environment of the circuit breaker in real time. The electrical parameters include: rated current, rated voltage, rated frequency, resistance and inductance; the mechanical characteristics include: spring stiffness of the circuit breaker, elastic modulus of circuit breaker components, size and component weight;

[0010] Step 2: Collect the temperature coefficient data of the circuit breaker material and the resistance of the circuit breaker at the standard temperature, and generate the real-time resistance of the circuit breaker at the real-time ambient temperature, wherein the standard temperature is 25°C;

[0011] Step 3: Generate the impedance of the circuit breaker according to the real-time resistance and inductance of the circuit breaker, establish the electrical equivalent circuit model of the circuit breaker through circuit simulation software according to the impedance, rated current and rated voltage, generate the power loss of the circuit breaker according to the simulation result of the circuit model, generate the power deviation through the power loss and rated power, and complete the establishment of the electrical equivalent circuit model when the power deviation is less than the power deviation threshold, otherwise adjust the parameter settings of the model;

[0012] Step 4: Generate the shear modulus of the circuit breaker according to the elastic modulus and Poisson's ratio of the circuit breaker material, import the mechanical characteristics of the circuit breaker into the finite element analysis software to build the mechanical model of the circuit breaker, generate the natural frequency of the circuit breaker according to the simulation results of the mechanical model, generate the frequency deviation through the natural frequency and the rated frequency, and complete the mechanical model establishment when the frequency deviation is less than the frequency deviation threshold, otherwise adjust the parameter settings of the model;

[0013] Step 5: Use voltage, current and frequency as state variables for detection, calculate the state variables based on the electrical equivalent circuit model and mechanical model simulation, generate dynamic thresholds for each state variable based on historical data of the state variables, and generate a fault judgment index based on the dynamic thresholds of the state variables and the real-time state variables to determine whether the current circuit breaker has a fault.

[0014] Furthermore, the formula for generating the real-time resistance of the circuit breaker at the real-time ambient temperature is:

[0015] R(T)=R0(1+α(T-T0))

[0016] Wherein, R(T) represents the resistance of the circuit breaker at the ambient temperature T, R0 represents the resistance of the circuit breaker at the standard temperature, T represents the real-time ambient temperature, T0 represents the standard temperature, α represents the temperature coefficient, and 0.003≤α≤0.004.

[0017] Furthermore, the principle on which the electrical equivalent circuit model of the circuit breaker is established is:

[0018] The impedance of the circuit breaker is generated based on the formula:

[0019] ω=2πf e

[0020] Z=R(T)+jωl0

[0021] Where ω represents the angular frequency, f e represents the rated frequency of the circuit breaker, R(T) represents the resistance of the circuit breaker at the ambient temperature T, l0 represents the inductance, and j represents the imaginary unit;

[0022] The circuit simulation software is: PSCAD;

[0023] In PSCAD, add and connect electrical components of resistance and inductance to form an equivalent circuit of the circuit breaker, add input voltage source and load current that are the same as the rated voltage and rated current of the circuit breaker, set the simulation step size and run time, and run the simulation;

[0024] The power loss is generated according to the formula:

[0025]

[0026] Among them, P S Indicates power loss, I e Indicates rated current;

[0027] The formula based on which the power deviation is generated is:

[0028]

[0029] Among them, Y P Indicates power deviation;

[0030] Set the power deviation threshold to 5% when -5% ≤ Y P When ≤5%, it means that the accuracy of the circuit model meets the requirements.

[0031] Furthermore, the principle on which the mechanical model of the circuit breaker is constructed is:

[0032] The formula used to generate the shear modulus of the circuit breaker is:

[0033]

[0034] Wherein, G represents the shear modulus of the circuit breaker, E represents the elastic modulus of the circuit breaker material, and v represents the Poisson's ratio of the circuit breaker material;

[0035] The finite element analysis software is: ANSYS;

[0036] The formula for generating the natural frequency of circuit breaker operation is based on:

[0037]

[0038] Among them, f n represents the natural frequency, k represents the spring stiffness, m represents the weight of the vibrating component,

[0039] The frequency deviation is generated based on the formula:

[0040]

[0041] Among them, Y f Indicates frequency deviation;

[0042] Set the frequency deviation threshold to 5%, when -5% ≤ Y f When ≤5%, it indicates that the accuracy of the mechanical model meets the requirements.

[0043] Furthermore, the principle for generating the dynamic threshold of each state variable is as follows:

[0044] The formula for generating the current dynamic threshold is:

[0045]

[0046] X I =k1(μ I +σ I )

[0047] Among them, μ I represents the average value of the current state variable in the historical data, N represents the number of current state variables in the historical data, I i represents the value of the i-th current state variable, i represents the index of the current state variable, σ I represents the standard deviation of the current state variable in the historical data, X I represents the current dynamic threshold, k1 represents the current safety factor;

[0048] The formula for generating the current fault judgment index is:

[0049]

[0050] Among them, B I Indicates the current fault judgment index, I indicates the real-time current;

[0051] The voltage dynamic threshold is generated based on the formula:

[0052]

[0053] X max (U) = μ U +k2σ U

[0054] X min (U) = μ U -k2σ U

[0055] Among them, μ U represents the average value of the voltage state variable in the historical data, M represents the number of voltage state variables in the historical data, and U k represents the value of the kth voltage state variable, k represents the index of the voltage state variable, σ U represents the standard deviation of the voltage state variable in the historical data, X max (U) represents the highest voltage dynamic threshold, X min (U) represents the minimum voltage dynamic threshold, k2 represents the voltage safety factor;

[0056] The formula for generating the voltage fault judgment index is:

[0057]

[0058] Among them, B U Indicates the voltage fault judgment index, U indicates the real-time voltage;

[0059] The principle on which the frequency dynamic threshold is generated is:

[0060]

[0061] X f =k3(μ f +σ f )

[0062] Among them, μ f represents the average value of the frequency state variables in the historical data, L represents the number of frequency state variables in the historical data, and f l represents the value of the lth frequency state variable, l represents the index of the frequency state variable, σ f represents the standard deviation of the frequency state variable in the historical data, X f represents the frequency dynamic threshold, k3 represents the frequency safety factor;

[0063] The formula for generating the frequency fault judgment index is:

[0064]

[0065] Among them, B f represents the frequency fault judgment index, and f represents the real-time frequency;

[0066] A comprehensive fault judgment index is generated according to the current fault judgment index, the voltage fault judgment index and the frequency fault judgment index. Further, the formula for generating the comprehensive fault judgment index is:

[0067] λ=4B I +2B U +B f

[0068] Among them, λ represents the comprehensive fault judgment index;

[0069] The comprehensive fault judgment index under the influence of the three judgment indexes has eight values ​​of 0, 1, 2, 3, 4, 5, 6, and 7. Each value corresponds to a value of the current, voltage, and frequency fault judgment index. The specific judgment principle is:

[0070] When λ=0, then B I =B U =B f =0, indicating that the current, voltage and frequency all exceed the threshold and there is a fault;

[0071] When λ=1, then B I =B U =0, B f =1, indicating that the current and voltage exceed the threshold, there is a fault, but the frequency does not have a fault;

[0072] When λ=2, then B I =B f =0, B U =1, indicating that the current and frequency exceed the threshold, there is a fault, but the voltage does not have a fault;

[0073] When λ=3, B I =0, B U =B f =1, indicating that the current exceeds the threshold and there is a fault, but there is no fault in the voltage and frequency;

[0074] When λ=4, then B I =1, B U =B f =0, indicating that both the voltage and frequency exceed the threshold, a fault exists, but the current does not have a fault;

[0075] When λ=5, B I =B f =1, B U =0, indicating that the voltage exceeds the threshold and a fault exists, but the current and frequency do not have a fault;

[0076] When λ=6, B I =B U =1, B f =0, indicating that the frequency exceeds the threshold and there is a fault, but the current and voltage do not have a fault;

[0077] When λ=7, B I =B U =B f =1, indicating that the current, voltage and frequency do not exceed the threshold and there is no fault.

[0078] The present invention also provides a circuit breaker fault early warning system based on digital twins, which is used to implement the above-mentioned circuit breaker fault early warning method based on digital twins, specifically comprising

[0079] A data acquisition module is used to collect electrical parameters and mechanical characteristics of the circuit breaker according to the technical manual, and collect ambient temperature data in the operating environment of the circuit breaker in real time. The electrical parameters include: rated current, rated voltage, rated frequency, resistance and inductance; the mechanical characteristics include: spring stiffness of the circuit breaker, elastic modulus, size and weight of components of the circuit breaker;

[0080] The temperature correction module is used to collect the temperature coefficient data of the circuit breaker material and the resistance of the circuit breaker at the standard temperature, and generate the real-time resistance of the circuit breaker at the real-time ambient temperature. The standard temperature is: 25°C;

[0081] A circuit model building module is used to generate the impedance of the circuit breaker according to the real-time resistance and inductance of the circuit breaker, establish the electrical equivalent circuit model of the circuit breaker through circuit simulation software according to the impedance, rated current and rated voltage, generate the loss power of the circuit breaker according to the simulation result of the circuit model, generate the power deviation through the loss power and the rated power, and complete the establishment of the electrical equivalent circuit model when the power deviation is less than the power deviation threshold, otherwise adjust the parameter settings of the model;

[0082] A mechanical model building module is used to generate the shear modulus of the circuit breaker according to the elastic modulus and Poisson's ratio of the circuit breaker material, import the mechanical characteristics of the circuit breaker into the finite element analysis software to build the mechanical model of the circuit breaker, generate the natural frequency of the circuit breaker according to the simulation results of the mechanical model, generate the frequency deviation through the natural frequency and the rated frequency, and complete the mechanical model building when the frequency deviation is less than the frequency deviation threshold, otherwise adjust the parameter settings of the model;

[0083] The comprehensive judgment module is used to use voltage, current and frequency as state variables for detection, calculate the state variables based on the electrical equivalent circuit model and mechanical model simulation, generate the dynamic threshold of each state variable according to the historical data of the state variable, and generate the fault judgment index according to the dynamic threshold of the state variable and the real-time state variable to judge whether the current circuit breaker has a fault.

[0084] Compared with the prior art, the present invention has the following beneficial effects:

[0085] The present invention uses 25°C as the standard ambient temperature, performs temperature correction on resistors that are easily affected by temperature, and reduces errors caused by temperature; an electrical equivalent circuit model is established through the electrical parameters of the circuit breaker, so that the electrical equivalent circuit model can be updated in real time to reflect changes in actual working conditions, and the accuracy of the circuit model is judged by calculating the power loss and rated power, providing accurate data support for fault detection, and the deviation threshold can be adjusted according to the actual application scenario, thereby enhancing the flexibility of the model.

[0086] The present invention also establishes a mechanical model through the mechanical characteristics of the circuit breaker, generates the natural frequency of the circuit breaker itself according to the simulation results of the mechanical model, adjusts the natural frequency according to the size relationship between the natural frequency and the frequency of the working environment and the working frequency inside the circuit breaker, reduces the resonance situation to reduce the failure probability of the circuit breaker, and enables the circuit breaker to flexibly adjust the mechanical characteristics according to the actual working environment to adapt to the working environment. The current, voltage and frequency are used as the state variables for detection, and the corresponding dynamic thresholds are generated. The fault judgment index is generated according to the size relationship between the real-time state variable value and the dynamic threshold to judge whether the corresponding parameter has a fault. This step combines the electrical equivalent circuit model and the mechanical model to comprehensively evaluate the working state of the circuit breaker. This integrated analysis method can identify problems that are difficult to detect with a single model, making the evaluation results more accurate and comprehensive; and the dynamic threshold is generated by using historical data, and the threshold can be adaptively adjusted according to the actual working environment and historical performance changes of the circuit breaker, avoiding the omission or false alarm caused by improper setting of the fixed threshold, and improving the accuracy of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 This is a schematic diagram of a method flow of an embodiment of the present invention;

[0088] Figure 2 Schematic diagram of system modules according to an embodiment of the present invention. DETAILED DESCRIPTION

[0089] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0090] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0091] Example:

[0092] See also Figure 1 , the present invention provides a technical solution:

[0093] A circuit breaker fault early warning method based on digital twin, the specific steps include:

[0094] Step 1: Collect the electrical parameters and mechanical characteristics of the circuit breaker according to the technical manual, and collect the ambient temperature data in the operating environment of the circuit breaker in real time. The electrical parameters include: rated current, rated voltage, rated frequency, resistance and inductance; the mechanical characteristics include: spring stiffness of the circuit breaker, elastic modulus of circuit breaker components, size and component weight;

[0095] Step 2: Collect the temperature coefficient data of the circuit breaker material and the resistance of the circuit breaker at the standard temperature, and generate the real-time resistance of the circuit breaker at the real-time ambient temperature, wherein the standard temperature is 25°C;

[0096] In this embodiment, the formula for generating the real-time resistance of the circuit breaker at the real-time ambient temperature is:

[0097] R(T)=R0(1+α(T-T0))

[0098] Wherein, R(T) represents the resistance of the circuit breaker at the ambient temperature T, R0 represents the resistance of the circuit breaker at the standard temperature, T represents the real-time ambient temperature, T0 represents the standard temperature, α represents the temperature coefficient, and 0.003≤α≤0.004.

[0099] For metal conductors, an increase in temperature will lead to an increase in resistance, and the temperature coefficient is a positive value. For non-metallic conductors, an increase in temperature will lead to a decrease in resistance, and the temperature coefficient is a negative value. The temperature coefficient indicates the sensitivity of the resistance of the circuit breaker material to changes in temperature. Usually, the conductive part of the circuit breaker uses metal materials such as copper or silver. Therefore, the temperature coefficient of the conductive material in the circuit breaker is in the range of 0.003 to 0.004. The resistance R(T) of the circuit breaker at ambient temperature T reflects the resistance of the circuit breaker after temperature correction. The resistance of the circuit breaker is proportional to the real-time ambient temperature and proportional to the resistance and temperature coefficient of the circuit breaker at standard temperature.

[0100] Step 3: Generate the impedance of the circuit breaker according to the real-time resistance and inductance of the circuit breaker, establish the electrical equivalent circuit model of the circuit breaker through circuit simulation software according to the impedance, rated current and rated voltage, generate the power loss of the circuit breaker according to the simulation result of the circuit model, generate the power deviation through the power loss and rated power, and complete the establishment of the electrical equivalent circuit model when the power deviation is less than the power deviation threshold, otherwise adjust the parameter settings of the model;

[0101] In this embodiment, the principle on which the electrical equivalent circuit model of the circuit breaker is established is:

[0102] The impedance of the circuit breaker is generated based on the formula:

[0103] ω=2πf e

[0104] Z=R(T)+jωl0

[0105] Where ω represents the angular frequency, f e represents the rated frequency of the circuit breaker, R(T) represents the resistance of the circuit breaker at the ambient temperature T, l0 represents the inductance, and j represents the imaginary unit;

[0106] The circuit simulation software is: PSCAD;

[0107] In PSCAD, drag and drop the resistor and inductor to the workspace, combine the two together to represent the impedance, and pre-input the previously calculated or determined values ​​for the resistor and inductor, connect the resistor and inductor to form the equivalent circuit of the circuit breaker, add an input voltage source with the same rated voltage, set the frequency and amplitude, add a load current with the same rated current, set the simulation time step and running time, perform simulation calculations, and obtain electrical characteristics such as voltage and current waveforms from the simulation results;

[0108] The power loss is generated according to the formula:

[0109]

[0110] Among them, P SIndicates power loss, I e Indicates rated current;

[0111] The formula based on which the power deviation is generated is:

[0112]

[0113] Among them, Y P Indicates power deviation;

[0114] Set the power deviation threshold to 5% when -5% ≤ Y P When ≤5%, it means that the accuracy of the circuit model meets the requirements.

[0115] The purpose of calculating the power loss through model simulation is to verify whether the circuit model is accurate. The power loss is compared with the rated power. If the deviation between the two is small, it means that the model is more accurate. Usually, the error is acceptable within ±5%. The specific power deviation threshold value can be determined according to the accuracy required for the actual application.

[0116] Step 4: Generate the shear modulus of the circuit breaker according to the elastic modulus and Poisson's ratio of the circuit breaker material, import the mechanical characteristics of the circuit breaker into the finite element analysis software to build the mechanical model of the circuit breaker, generate the natural frequency of the circuit breaker according to the simulation results of the mechanical model, generate the frequency deviation through the natural frequency and the rated frequency, and complete the mechanical model establishment when the frequency deviation is less than the frequency deviation threshold, otherwise adjust the parameter settings of the model;

[0117] In this embodiment, the principle for constructing the mechanical model of the circuit breaker is:

[0118] The formula used to generate the shear modulus of the circuit breaker is:

[0119]

[0120] Wherein, G represents the shear modulus of the circuit breaker, E represents the elastic modulus of the circuit breaker material, and v represents the Poisson's ratio of the circuit breaker material;

[0121] The shear modulus of a circuit breaker reflects the ability of the circuit breaker material to resist deformation under shear force, and indicates how much shear strain the material will produce when shear force is applied inside the material. The shear modulus helps predict the deformation and stress distribution of circuit breaker components under actual use conditions, and reflects the service life of the components.

[0122] The finite element analysis software is: ANSYS;

[0123] The formula for generating the natural frequency of circuit breaker operation is based on:

[0124]

[0125] Among them, f n represents the natural frequency, k represents the spring stiffness, and m represents the weight of the vibrating component;

[0126] The natural frequency reflects the natural vibration frequency determined by the stiffness and mass characteristics of the component material when there is no external driving force. When the natural frequency is too close to the rated frequency of the system, it may cause resonance and reduce the service life of the component. Therefore, the natural frequency should be kept away from the rated frequency.

[0127] The frequency deviation is generated based on the formula:

[0128]

[0129] Among them, Y f Indicates frequency deviation;

[0130] Set the frequency deviation threshold to 5%. f ≤-5% or Y f When it is ≥5%, it indicates that the accuracy of the mechanical model meets the requirements.

[0131] The purpose of calculating the natural frequency through mechanical model simulation is to avoid resonance and verify whether the design of the circuit breaker can simultaneously meet the vibration conditions in the environment and the vibration conditions inside the circuit breaker. The natural frequency can be changed by adjusting the mass of the effective area of ​​the vibrating component so that the natural frequency is closer to the frequency that may be generated during the operation of the circuit breaker.

[0132] Step 5: Use voltage, current and frequency as state variables for detection, calculate the state variables based on the electrical equivalent circuit model and mechanical model simulation, generate dynamic thresholds for each state variable based on historical data of the state variables, and generate a fault judgment index based on the dynamic thresholds of the state variables and the real-time state variables to determine whether the current circuit breaker has a fault.

[0133] Generate real-time current, real-time voltage and real-time frequency based on the electrical equivalent circuit model and the mechanical model, and compare them with the corresponding dynamic thresholds;

[0134] The principle for generating dynamic thresholds for each state variable is:

[0135] The formula for generating the current dynamic threshold is:

[0136]

[0137] X I =k1(μ I +σ I )

[0138] Among them, μ Irepresents the average value of the current state variable in the historical data, N represents the number of current state variables in the historical data, I i represents the value of the i-th current state variable, i represents the index of the current state variable, σ I represents the standard deviation of the current state variable in the historical data, X I represents the current dynamic threshold, k1 represents the current safety factor;

[0139] The current dynamic threshold reflects the upper limit of the current at which the electrical system can operate safely. It is calculated based on the current data in the historical data. The current safety factor is used to adjust the sensitivity of the current dynamic threshold. For circuit systems that are very sensitive to current changes and require rapid detection and response, a smaller current safety factor is selected to reduce the dynamic threshold; for circuit systems with strong durability or used to handle larger currents and have a higher risk tolerance, a larger current safety factor is selected to reduce the possibility of false alarms. The smaller current safety factor ranges from 1.0 to 1.3, and the larger current safety factor ranges from 1.5 to 1.8.

[0140] The formula for generating the current fault judgment index is:

[0141]

[0142] Among them, B I Indicates the current fault judgment index, I indicates the real-time current;

[0143] The current fault judgment index reflects the relationship between the real-time current and the current dynamic threshold. The current fault judgment index is logically judged by the size relationship between the two, so that the current fault judgment index takes a value of 1 or 0. When the current fault judgment index takes a value of 1, it indicates that the real-time current does not exceed the current dynamic threshold, and there is no need to issue an early warning for the current. When the current fault judgment index takes a value of 0, it indicates that the real-time current exceeds the current dynamic threshold, and an early warning is required for the current.

[0144] The voltage dynamic threshold is generated based on the formula:

[0145]

[0146] X max (U) = μ U +k2σ U

[0147] X min (U) = μ U -k2σ U

[0148] Among them, μ Urepresents the average value of the voltage state variable in the historical data, M represents the number of voltage state variables in the historical data, and U k represents the value of the kth voltage state variable, k represents the index of the voltage state variable, σ U represents the standard deviation of the voltage state variable in the historical data, X max (U) represents the highest voltage dynamic threshold, X min (U) represents the minimum voltage dynamic threshold, k2 represents the voltage safety factor;

[0149] The voltage dynamic threshold reflects the voltage range in which the electrical system can operate safely and stably. Therefore, the voltage dynamic threshold is a range between the highest voltage dynamic threshold and the lowest voltage dynamic threshold. The voltage safety factor ranges from 1 to 2. When the monitoring scenario is strict and the fault rate tolerance is low, a smaller voltage safety factor is selected, such as 1 to 1.2. When the fault rate tolerance is high and the voltage fluctuation is large, a larger voltage safety factor is selected, such as 1.5 to 2.0, to reduce false alarms.

[0150] The formula for generating the voltage fault judgment index is:

[0151]

[0152] Among them, B U Indicates the voltage fault judgment index, U indicates the real-time voltage;

[0153] The voltage fault judgment index reflects the relationship between the real-time voltage and the highest voltage dynamic threshold and the lowest voltage dynamic threshold. When the real-time voltage is within the highest voltage dynamic threshold and the lowest voltage dynamic threshold, the voltage fault judgment index takes a value of 1, indicating that the real-time voltage does not exceed the threshold and no early warning is required. When the real-time voltage is less than the lowest voltage dynamic threshold or greater than the highest voltage dynamic threshold, it means that the real-time voltage exceeds the threshold and an early warning is required.

[0154] The principle on which the frequency dynamic threshold is generated is:

[0155]

[0156] X f =k3(μ f +σ f )

[0157] Among them, μ f represents the average value of the frequency state variables in the historical data, L represents the number of frequency state variables in the historical data, and f l represents the value of the lth frequency state variable, l represents the index of the frequency state variable, σ f represents the standard deviation of the frequency state variable in the historical data, X frepresents the frequency dynamic threshold, K3 represents the frequency safety factor;

[0158] The value range of the frequency safety index is 1 to 2. When the monitoring scenario is strict and the fault rate tolerance is low, a smaller frequency safety factor is selected to ensure accuracy, such as 1 to 1.3. When the fault rate tolerance is high and the frequency fluctuation is large, a larger frequency safety factor is selected, such as 1.5 to 2.0, to reduce false alarms.

[0159] The formula for generating the frequency fault judgment index is:

[0160]

[0161] Among them, B f represents the frequency fault judgment index, and f represents the real-time frequency;

[0162] The frequency fault judgment index reflects the relationship between the real-time operating frequency and the frequency dynamic threshold. When the real-time operating frequency is less than the frequency dynamic threshold, the frequency fault judgment index takes a value of 1, indicating that the real-time operating frequency does not exceed the threshold and no warning is required. When the real-time operating frequency is greater than the frequency dynamic threshold, the frequency fault judgment index takes a value of 0, indicating that the real-time operating frequency exceeds the threshold and a warning needs to be issued.

[0163] A comprehensive fault judgment index is generated according to the current fault judgment index, the voltage fault judgment index and the frequency fault judgment index.

[0164] The formula for generating the comprehensive fault judgment index is:

[0165] λ=4B I +2B U +B f

[0166] Among them, λ represents the comprehensive fault judgment index;

[0167] The comprehensive fault judgment index under the influence of the three judgment indexes has eight values ​​of 0, 1, 2, 3, 4, 5, 6, and 7. Each value corresponds to a value of the current, voltage, and frequency fault judgment index. The specific judgment principle is:

[0168] When λ=0, then B I =B U =B f =0, indicating that the current, voltage and frequency all exceed the threshold and there is a fault;

[0169] When λ=1, then B I =B U =0, B f =1, indicating that the current and voltage exceed the threshold, there is a fault, but the frequency does not have a fault;

[0170] When λ=2, then B I =B f =0, B U =1, indicating that the current and frequency exceed the threshold, there is a fault, but the voltage does not have a fault;

[0171] When λ=3, B I =0, B U =B f =1, indicating that the current exceeds the threshold and there is a fault, but there is no fault in the voltage and frequency;

[0172] When λ=4, then B I =1, B U =B f =0, indicating that both the voltage and frequency exceed the threshold, a fault exists, but the current does not have a fault;

[0173] When λ=5, B I =B f =1, B U =0, indicating that the voltage exceeds the threshold and a fault exists, but the current and frequency do not have a fault;

[0174] When λ=6, B I =B U =1, B f =0, indicating that the frequency exceeds the threshold and there is a fault, but the current and voltage do not have a fault;

[0175] When λ=7, B I =B U =B f =1, indicating that the current, voltage and frequency do not exceed the threshold and there is no fault.

[0176] In the above judgment process, the value of each comprehensive fault judgment index corresponds to a set of different current fault judgment indexes, voltage fault judgment indexes and frequency fault judgment indexes, and the values ​​of the three indexes can be directly and accurately inferred based on the comprehensive fault judgment index.

[0177] See also Figure 2 The present invention also provides a circuit breaker fault early warning system based on digital twins, which is used to implement the above-mentioned circuit breaker fault early warning method based on digital twins, and specifically includes:

[0178] A data acquisition module is used to collect electrical parameters and mechanical characteristics of the circuit breaker according to the technical manual, and collect ambient temperature data in the operating environment of the circuit breaker in real time. The electrical parameters include: rated current, rated voltage, rated frequency, resistance and inductance; the mechanical characteristics include: spring stiffness of the circuit breaker, elastic modulus, size and weight of components of the circuit breaker;

[0179] The temperature correction module is used to collect the temperature coefficient data of the circuit breaker material and the resistance of the circuit breaker at the standard temperature, and generate the real-time resistance of the circuit breaker at the real-time ambient temperature. The standard temperature is: 25°C;

[0180] A circuit model building module is used to generate the impedance of the circuit breaker according to the real-time resistance and inductance of the circuit breaker, establish the electrical equivalent circuit model of the circuit breaker through circuit simulation software according to the impedance, rated current and rated voltage, generate the loss power of the circuit breaker according to the simulation result of the circuit model, generate the power deviation through the loss power and the rated power, and complete the establishment of the electrical equivalent circuit model when the power deviation is less than the power deviation threshold, otherwise adjust the parameter settings of the model;

[0181] A mechanical model building module is used to generate the shear modulus of the circuit breaker according to the elastic modulus and Poisson's ratio of the circuit breaker material, import the mechanical characteristics of the circuit breaker into the finite element analysis software to build the mechanical model of the circuit breaker, generate the natural frequency of the circuit breaker according to the simulation results of the mechanical model, generate the frequency deviation through the natural frequency and the rated frequency, and complete the mechanical model building when the frequency deviation is less than the frequency deviation threshold, otherwise adjust the parameter settings of the model;

[0182] The comprehensive judgment module is used to use voltage, current and frequency as state variables for detection, calculate the state variables based on the electrical equivalent circuit model and mechanical model simulation, generate the dynamic threshold of each state variable according to the historical data of the state variable, and generate the fault judgment index according to the dynamic threshold of the state variable and the real-time state variable to judge whether the current circuit breaker has a fault.

[0183] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0184] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. Those skilled in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0185] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0186] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A circuit breaker fault early warning method based on digital twin, characterized in that: The specific steps include: Step 1: Collect the electrical parameters and mechanical characteristics of the circuit breaker according to the technical manual, and collect the ambient temperature data in the operating environment of the circuit breaker in real time. The electrical parameters include: rated current, rated voltage, rated frequency, resistance and inductance; the mechanical characteristics include: spring stiffness of the circuit breaker, elastic modulus of circuit breaker components, size and component weight; Step 2: Collect the temperature coefficient data of the circuit breaker material and the resistance of the circuit breaker at the standard temperature, and generate the real-time resistance of the circuit breaker at the real-time ambient temperature, wherein the standard temperature is 25°C; Step 3: Generate the impedance of the circuit breaker according to the real-time resistance and inductance of the circuit breaker, establish the electrical equivalent circuit model of the circuit breaker through circuit simulation software according to the impedance, rated current and rated voltage, generate the power loss of the circuit breaker according to the simulation result of the circuit model, generate the power deviation through the power loss and rated power, and complete the establishment of the electrical equivalent circuit model when the power deviation is less than the power deviation threshold, otherwise adjust the parameter settings of the model; Step 4: Generate the shear modulus of the circuit breaker according to the elastic modulus and Poisson's ratio of the circuit breaker material, import the mechanical characteristics of the circuit breaker into the finite element analysis software to build the mechanical model of the circuit breaker, generate the natural frequency of the circuit breaker according to the simulation results of the mechanical model, generate the frequency deviation through the natural frequency and the rated frequency, and complete the mechanical model establishment when the frequency deviation is less than the frequency deviation threshold, otherwise adjust the parameter settings of the model; Step 5: Use voltage, current and frequency as state variables for detection, calculate the state variables based on the electrical equivalent circuit model and mechanical model simulation, generate dynamic thresholds for each state variable based on historical data of the state variables, and generate a fault judgment index based on the dynamic thresholds of the state variables and the real-time state variables to determine whether the current circuit breaker has a fault.

2. A circuit breaker fault early warning method based on digital twin according to claim 1, characterized in that: The formula for generating the real-time resistance of the circuit breaker at the real-time ambient temperature in step 2 is: R(T)=R0(1+α(T-T0)) Wherein, R(T) represents the resistance of the circuit breaker at the ambient temperature T, R0 represents the resistance of the circuit breaker at the standard temperature, T represents the real-time ambient temperature, T0 represents the standard temperature, α represents the temperature coefficient, and 0.003≤α≤0.

004.

3. The circuit breaker fault early warning method based on digital twin according to claim 1 is characterized in that: The principle on which the electrical equivalent circuit model of the circuit breaker is established in step 3 is: The impedance of the circuit breaker is generated based on the formula: ω=2πf e Z=R(T)+jωl0 Where ω represents the angular frequency, f e represents the rated frequency of the circuit breaker, R(T) represents the resistance of the circuit breaker at the ambient temperature T, l0 represents the inductance, and j represents the imaginary unit; The circuit simulation software is: PSCAD; In PSCAD, add and connect electrical components of resistance and inductance to form an equivalent circuit of the circuit breaker, add input voltage source and load current that are the same as the rated voltage and rated current of the circuit breaker, set the simulation step size and run time, and run the simulation; The power loss is generated according to the formula: Among them, P S Indicates power loss, I e Indicates rated current; The formula based on which the power deviation is generated is: Among them, Y P Indicates power deviation; Set the power deviation threshold to 5% when -5% ≤ Y P When ≤5%, it means that the accuracy of the circuit model meets the requirements.

4. The circuit breaker fault early warning method based on digital twin according to claim 1 is characterized in that: The principle on which the mechanical model of the circuit breaker is constructed in step 4 is: The formula used to generate the shear modulus of the circuit breaker is: Wherein, G represents the shear modulus of the circuit breaker, E represents the elastic modulus of the circuit breaker material, and v represents the Poisson's ratio of the circuit breaker material; The finite element analysis software is: ANSYS; The formula for generating the natural frequency of circuit breaker operation is based on: Among them, f n represents the natural frequency, k represents the spring stiffness, m represents the weight of the vibrating component, The frequency deviation is generated based on the formula: Among them, Y f Indicates frequency deviation; Set the frequency deviation threshold to 5%, when -5% ≤ Y f When ≤5%, it indicates that the accuracy of the mechanical model meets the requirements.

5. The circuit breaker fault early warning method based on digital twin according to claim 1 is characterized in that: The principle for generating the dynamic threshold of each state variable in step 5 is: The formula for generating the current dynamic threshold is: X I =k1(μ I +s I ) Among them, μ I represents the average value of the current state variable in the historical data, N represents the number of current state variables in the historical data, I i represents the value of the i-th current state variable, i represents the index of the current state variable, σ I represents the standard deviation of the current state variable in the historical data, X I represents the current dynamic threshold, k1 represents the current safety factor; The formula for generating the current fault judgment index is: Among them, B I Indicates the current fault judgment index, I indicates the real-time current; The voltage dynamic threshold is generated based on the formula: X max (U)=μ U +k2σ U X min (U)=μ U -k2σ U Among them, μ U represents the average value of the voltage state variable in the historical data, M represents the number of voltage state variables in the historical data, and U k represents the value of the kth voltage state variable, k represents the index of the voltage state variable, σ U represents the standard deviation of the voltage state variable in the historical data, X max (U) represents the highest voltage dynamic threshold, X min (U) represents the minimum voltage dynamic threshold, k2 represents the voltage safety factor; The formula for generating the voltage fault judgment index is: Among them, B U Indicates the voltage fault judgment index, U indicates the real-time voltage; The principle on which the frequency dynamic threshold is generated is: X f =k3(μ f +s f ) Among them, μ f represents the average value of the frequency state variables in the historical data, L represents the number of frequency state variables in the historical data, and f l represents the value of the lth frequency state variable, l represents the index of the frequency state variable, σ f represents the standard deviation of the frequency state variable in the historical data, X f represents the frequency dynamic threshold, k3 represents the frequency safety factor; The formula for generating the frequency fault judgment index is: Among them, B f represents the frequency fault judgment index, and f represents the real-time frequency; A comprehensive fault judgment index is generated according to the current fault judgment index, the voltage fault judgment index and the frequency fault judgment index.

6. A circuit breaker fault early warning method based on digital twin according to claim 5, characterized in that: The formula for generating the comprehensive fault judgment index is: λ=4B I +2B U +B f Among them, λ represents the comprehensive fault judgment index; The comprehensive fault judgment index under the influence of the three judgment indexes has eight values ​​of 0, 1, 2, 3, 4, 5, 6, and 7. Each value corresponds to a value of the current, voltage, and frequency fault judgment index. The specific judgment principle is: When λ=0, then B I =B U =B f =0, indicating that the current, voltage and frequency all exceed the threshold and there is a fault; When λ=1, then B I =B U =0, B f =1, indicating that the current and voltage exceed the threshold, there is a fault, but the frequency does not have a fault; When λ=2, then B I =B f =0, B U =1, indicating that the current and frequency exceed the threshold, there is a fault, but the voltage does not have a fault; When λ=3, B I =0, B U =B f =1, indicating that the current exceeds the threshold and there is a fault, but there is no fault in the voltage and frequency; When λ=4, then B I =1, B U =B f =0, indicating that both the voltage and frequency exceed the threshold, a fault exists, but the current does not have a fault; When λ=5, B I =B f =1, B U =0, indicating that the voltage exceeds the threshold and a fault exists, but the current and frequency do not have a fault; When λ=6, then B I =B U =1, B f =0, indicating that the frequency exceeds the threshold and there is a fault, but there is no fault in the current and voltage; When λ=7, B I =B U =B f =1, indicating that the current, voltage and frequency do not exceed the threshold and there is no fault.

7. A circuit breaker fault early warning system based on digital twins, characterized by: The system is used to implement the above-mentioned circuit breaker fault early warning method based on digital twin, specifically including: A data acquisition module is used to collect electrical parameters and mechanical characteristics of the circuit breaker according to the technical manual, and collect ambient temperature data in the operating environment of the circuit breaker in real time. The electrical parameters include: rated current, rated voltage, rated frequency, resistance and inductance; the mechanical characteristics include: spring stiffness of the circuit breaker, elastic modulus, size and weight of components of the circuit breaker; The temperature correction module is used to collect the temperature coefficient data of the circuit breaker material and the resistance of the circuit breaker at the standard temperature, and generate the real-time resistance of the circuit breaker at the real-time ambient temperature. The standard temperature is: 25°C; A circuit model building module is used to generate the impedance of the circuit breaker according to the real-time resistance and inductance of the circuit breaker, establish the electrical equivalent circuit model of the circuit breaker through circuit simulation software according to the impedance, rated current and rated voltage, generate the loss power of the circuit breaker according to the simulation result of the circuit model, generate the power deviation through the loss power and the rated power, and complete the establishment of the electrical equivalent circuit model when the power deviation is less than the power deviation threshold, otherwise adjust the parameter settings of the model; A mechanical model building module is used to generate the shear modulus of the circuit breaker according to the elastic modulus and Poisson's ratio of the circuit breaker material, import the mechanical characteristics of the circuit breaker into the finite element analysis software to build the mechanical model of the circuit breaker, generate the natural frequency of the circuit breaker according to the simulation results of the mechanical model, generate the frequency deviation through the natural frequency and the rated frequency, and complete the mechanical model building when the frequency deviation is less than the frequency deviation threshold, otherwise adjust the parameter settings of the model; The comprehensive judgment module is used to use voltage, current and frequency as state variables for detection, calculate the state variables based on the electrical equivalent circuit model and mechanical model simulation, generate the dynamic threshold of each state variable according to the historical data of the state variable, and generate the fault judgment index according to the dynamic threshold of the state variable and the real-time state variable to judge whether the current circuit breaker has a fault.

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