A method and terminal for surge testing modeling of an electrical system

Abstract

The application provides a surge test modeling method and terminal for an electrical system, which establishes a lightning surge interference source model, a device port and an impulse voltage conduction path model, a device insulation coordination model and a lightning protection device model, is used for simulating and testing the response behavior of lightning surge interference of a low-voltage electrical system, realizes process evaluation of lightning protection measures and lightning protection device selection of the system to analyze whether the lightning protection measures of the electrical system connected to a power distribution network are appropriate, whether main facilities and devices will be damaged after a lightning stroke, whether significant safety consequences will be caused and whether the selection of lightning protection devices is reasonable, avoids damage to the devices in actual tests, provides a basis for the design of lightning protection of the electrical system, and uses the principle of a controlled voltage source to establish a lightning protection device model of a surge protection device and make the voltage protection level parameter of the surge protection device output according to a current value, so that the voltage protection level parameter reaches the voltage resistance and clamping characteristics of the surge protection device when the surge protection device acts.

Description

[0001] This application is a divisional application of the invention patent with the application date of September 4, 2024, the application number of 202411231521.8, and the name of "a surge test modeling simulation method and terminal for electrical system", which is the parent application. TECHNICAL FIELD

[0002] The present application relates to the technical field of power systems, in particular to a surge test modeling method and terminal for electrical system. BACKGROUND

[0003] Lightning overvoltage is one of the important reasons for power system failure. For low-voltage distribution network, user equipment is placed in buildings, and buildings are constructed according to lightning protection grounding design requirements, so that user equipment has certain resistance to overvoltage on the line caused by lightning.

[0004] Many direct current power generation equipment and low-voltage distribution network are integrated, especially after the integration of electrochemical energy storage batteries and photovoltaic power generation equipment into the distribution network, the lightning protection facilities and line lightning protection level constructed for alternating current distribution network are not enough to protect the new equipment, and the damage consequences of direct current line after lightning strike are different from those of alternating current line. It is difficult to analyze whether the lightning protection measures for the electrical system connected to the distribution network are appropriate, whether the main facilities and equipment will be damaged after lightning strike, whether significant safety consequences will be caused, and whether the selection of lightning protection protection devices is reasonable. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a surge test modeling method and terminal for electrical system, so as to quickly evaluate the lightning protection process of electrical system, avoid damage to equipment in actual test, and provide a basis for the design of electrical system lightning protection.

[0006] In order to solve the above technical problems, the technical scheme adopted by the present application is:

[0007] A surge test modeling method for electrical system, comprising the steps of:

[0008] S1, a common mode conduction method is used to establish a lightning surge interference source model for the electric wave of induced lightning, so that the parameters of the lightning wave generated at the position of the electrical system are adjustable, and the degree of simulation lightning surge interference source entering the interface of the electrical system through the common mode line is simulated;

[0009] S2, identifying the equipment in the electrical system which is easily affected by lightning overvoltage or overcurrent, the induction position port and the conduction path of the impulse voltage, and establishing a device insulation coordination model for the insulation coordination of the induction position port of the equipment;

[0010] S3, establishing a device insulation coordination model for the insulation coordination of the induction position port of the equipment identified in the electrical system;

[0011] S4, lightning protection device model is established for the lightning surge protection device, specifically:

[0012] S41, the lightning protection device model of the surge protection device is established by using the principle of controlled voltage source, so that the voltage protection level parameter U k According to the current value output, the lightning protection device model is as follows formula (4):

[0013]

[0014] Wherein, U in is the impulse voltage applied to the surge protection device, U P is the voltage protection level of the surge protection device, U res is the residual voltage after protection action, I in and I max are the current and the maximum allowable current flowing through the surge protection device after protection action respectively.

[0015] S42, the curve of U res -I in is taken N points, and the expression of the residual voltage U res_N of the Nth point after piecewise linearization is as follows formula (5):

[0016] U res_N =A N +B N I in_N (5);

[0017] Wherein, A N and B N are the expression coefficients of the Nth point after linearization.

[0018] In order to solve the above technical problems, another technical scheme adopted by the application is:

[0019] An electrical system surge test modeling terminal, comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to realize the steps of the above-mentioned electrical system surge test modeling method.

[0020] The application has the advantages that: a surge test modeling method and terminal of an electrical system are provided, a lightning surge interference source model, a device port and an impulse voltage conduction path model, a device insulation coordination model and a lightning protection device model are established, the response behavior of lightning surge interference of a low-voltage electrical system is simulated and tested, the selection of lightning protection measures and lightning protection devices of the system is evaluated in a process, whether the lightning protection measures of the electrical system after being connected to a power distribution network are appropriate, whether the main facilities and devices are damaged after being struck by lightning, whether significant safety consequences will be caused, and whether the selection of lightning protection devices is reasonable are effectively analyzed, damage to the devices in actual testing is avoided, the design of lightning protection of the electrical system has a basis, and the voltage protection level parameter of the surge protection device model of the surge protection device is established by using the principle of a controlled voltage source and the voltage protection level parameter of the surge protection device is output according to the current value, so that the voltage protection and clamping characteristics of the surge protection device when the surge protection device is actually operated are simulated. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A whole flowchart of a surge test modeling method of an electrical system according to an embodiment of the application;

[0022] Figure 2 A system architecture diagram after a lightning rod of a lightning struck building according to an embodiment of the application;

[0023] Figure 3 A circuit principle diagram of four models established by using MatLab / Simulink according to an embodiment of the application;

[0024] Figure 4 A relationship curve between voltage and current and time in a surge generator in a simulation process of establishing four models according to an embodiment of the application;

[0025] Figure 5 A relationship curve between voltage and current and time of a surge generator and a surge protection device and a relationship curve between surge common-mode voltage and time between a Batt-same inductive position grounding point FND in a simulation process of establishing four models according to an embodiment of the application;

[0026] Figure 6 A specific flowchart of a surge test modeling method of an electrical system according to an embodiment of the application;

[0027] Figure 7 A structure schematic diagram of a surge test modeling terminal of an electrical system according to an embodiment of the application.

[0028] Label explanation:

[0029] 1. A surge test modeling terminal of an electrical system; 2. A memory; 3. A processor. DETAILED DESCRIPTION

[0030] To explain the technical content, the purpose and effect of the present application in detail, the following is described in conjunction with the embodiments and the accompanying drawings.

[0031] Please refer to Figures 1 to 6 A surge test modeling method of an electrical system, comprising the steps of:

[0032] S1, using a common mode conduction method to establish a lightning surge interference source model for the electric wave of induced lightning;

[0033] S2, identifying the devices in the electrical system that are susceptible to lightning overvoltage or overcurrent, their induction position ports and the conduction path of the impulse voltage, and establishing a device port and impulse voltage conduction path model;

[0034] S3, establishing a device insulation coordination model for the induction position ports of the identified devices in the electrical system;

[0035] S4, establishing a lightning protection device model for the lightning protection surge protection device;

[0036] S5, simulating the lightning protection process of the electrical system based on the lightning surge interference source model, the device port and impulse voltage conduction path model, the device insulation coordination model and the lightning protection device model.

[0037] From the above description, the beneficial effects of the present application are that a surge test modeling method of an electrical system is provided, which simulates the response behavior of the lightning surge interference of a low-voltage electrical system by establishing a lightning surge interference source model, a device port and impulse voltage conduction path model, a device insulation coordination model and a lightning protection device model, realizes the process evaluation of the selection of lightning protection measures and lightning protection devices of the system, effectively analyzes whether the lightning protection measures of the electrical system after being connected to the power distribution network are appropriate, whether the main facility devices will be damaged after being struck by lightning, whether significant safety consequences will be caused, and whether the selection of lightning protection devices is reasonable, avoids damage to the devices in actual testing, and provides a basis for the design of lightning protection of the electrical system.

[0038] Further, the step S1 is specifically:

[0039] S11, decomposing the lightning transient process of induced lightning, using an exponential function to describe the process of overvoltage generated by lightning on the common ground network of electrical system devices and other buildings after the lightning strikes the lightning rod set up by the building, and the induced lightning impulse occurs at the induction position of the grounding system of the lightning position down lead to ground, when the lightning position is struck, the impulse voltage generated at the induction position is as follows Formula (1):

[0040]

[0041] wherein R GND_i is the ground system DC resistance from the lightning strike position to the induction position, i represents the count in the formula, I P1 is the maximum lightning current at the lightning strike position to the shunt current on the common ground network, τ1 is the time constant of the lightning current rise, τ2 is the time constant of the lightning current drop, and k is a coefficient;

[0042] S12, obtaining the peak value of the maximum lightning current through the lightning weather history data at the location of the electrical system;

[0043] S13, obtaining the ground system DC resistance R GND_i from the lightning strike position to the induction position through measurement or equivalent calculation;

[0044] S14, obtaining the values of τ1 and τ2 according to the lightning current level at the induction position;

[0045] S15, establishing the interference source V P in the simulation tool, so that its expression is shown in formula (1), and based on formula (1), the lightning surge interference source model of the surge generator is established;

[0046] S16, controlling the output resistance of the interference source V P in the surge generator, so that the output current is adjusted between 0 and I P1 .

[0047] From the above description, by establishing the lightning surge interference source model of the surge generator, the parameters of the main lightning wave generated at the location of the electrical system can be adjusted, so as to simulate the degree of the lightning surge interference source entering the electrical system interface through the common mode line.

[0048] The step S14 is specifically:

[0049] According to whether the installation position of the electrical system is inside or outside the building, two lightning current levels are divided;

[0050] The lightning current level located outside the building is defined as level one, and the time constants τ1=5-10 μs and τ2=100-350 μs are taken;

[0051] The lightning current level located inside the building is defined as level two, and the time constants τ1=0.25-1.2 μs and τ2=50-100 μs are taken.

[0052] From the above description, it can be seen that the lightning current grade is classified according to the installation position of the electrical system, wherein the grade one is located outside the building, which indicates that it is seriously affected by lightning, and therefore the setting range of the two time constants is large, and the grade two is located inside the building, which indicates that it is slightly affected by lightning, and therefore the setting range of the two time constants is small.

[0053] The step S2 is specifically:

[0054] S21, identifying all lightning impulse sensitive devices in the electrical system;

[0055] S22, identifying the power ports and signal ports of all devices relative to the common ground network in the electrical system;

[0056] S23, simulating all transmission paths according to the connection of the identified power ports and signal ports relative to different grounding points to the induction position, to obtain a device port and impulse voltage transmission path model.

[0057] The step S21 is specifically:

[0058] In the lightning strike on the building lightning rod, the components inside the power units and control units in the electrical system connected to the building power distribution network and containing the power units and control units are identified as sensitive devices, which are easily affected by overvoltage or overcurrent;

[0059] The step S22 is specifically:

[0060] According to the requirements of standard GB / T 17799.2 and the requirements of the equipment specification, the power ports with direct current power input / output function and alternating current power input / output function and the signal ports with signal transmission function are identified.

[0061] From the above description, it can be seen that the power units and control units of the electrical system are easily affected by overvoltage and overcurrent, which will affect the safe operation of the equipment, so they are taken as sensitive devices; at the same time, the power ports and signal ports of all devices relative to the same common ground network in the electrical system can bear the impulse voltage generated by lightning, so these ports need to be identified, so that the model is established by simulating the transmission paths of each port relative to different grounding points to the induction position, in order to simulate the lightning process.

[0062] The step S3 is specifically:

[0063] S31, establishing a device insulation coordination model with insulation medium breakdown characteristics:

[0064]

[0065] Wherein, R is the insulation resistance of the insulation medium, p1 is the resistivity of the insulation medium under normal conditions, d is the material thickness of the insulation medium, k1 and k2 are respectively the coefficients of the resistivity related to the ambient temperature and humidity of the insulation medium under normal conditions, p2 is the resistivity of the insulation medium under breakdown conditions, E is the voltage field strength borne by the insulation medium, ε is the dielectric constant of the insulation medium, k3 and k4 are respectively the coefficients of the voltage field strength related to the ambient temperature and humidity of the insulation medium under breakdown conditions;

[0066] S32, obtain ε of the insulation medium through the material manual, and obtain k1, k2, k3 and k4 of the insulation medium through the test method, and substitute into formula (2);

[0067] S33, define two failure modes of the insulation medium, i.e. the leakage current failure and the breakdown failure:

[0068] When the insulation resistance p2d < R < R limit And E < εdk3k4, it is the leakage current failure, and:

[0069]

[0070] Wherein, U N_max is the maximum working voltage of the port where the insulation medium is located, I safe is the safety leakage current, R limit is the safety insulation resistance limit value of the insulation medium;

[0071] When E ≥ εdk3k4, it is the breakdown failure.

[0072] From the above description, it can be known that the insulation coordination represents the voltage resistance capability of the insulation material, the equipment insulation coordination model is established based on the breakdown characteristics of the insulation medium, the insulation coordination design of the port of the equipment is ensured to bear the impact voltage, so that the port will not be damaged by overvoltage breakdown or overcurrent; meanwhile, two failure modes including the leakage current failure and the breakdown failure are defined in the equipment insulation coordination model, so that it is convenient to analyze which failure in the subsequent simulation.

[0073] The step S4 is specifically:

[0074] S41, a lightning protection device model of the surge protection device is established using the principle of the controlled voltage source, so that the voltage protection level parameter U k According to the current value output, the lightning protection device model is as follows:

[0075]

[0076] Wherein, U inU is the impulse voltage applied across the surge protector. P U represents the voltage protection level of the surge protector. res To protect against residual voltage after the operation, I in and I max These are the current flowing through the surge protector after the protection action and the maximum allowable current value, respectively.

[0077] S42, U res -I in By taking N points from the curve, the residual voltage U at the Nth point after piecewise linearization is obtained. res_N The expression is as follows: Formula (5):

[0078] U res_N =A N +B N I in_N (5);

[0079] Among them, A N and B N It is the coefficient of the Nth point expression after linearization.

[0080] As described above, the surge protector's lightning protection device model is established using the controlled voltage source principle, and the voltage protection level parameter of the surge protector is output according to the current value, thereby simulating the varistor and clamping characteristics when the real surge protector operates.

[0081] Step S5 specifically involves:

[0082] S51. When no surge protectors are installed at any of the device ports, and the temperature of the insulating medium is outside the range of -20 to 50°C or the humidity is outside the range of 0 to 95%, simulation is performed based on the lightning surge interference source model, the device port and impulse voltage conduction path model, the device insulation coordination model, and the lightning protection device model. If the leakage current failure does not occur, proceed to step S52. Otherwise, adjust the parameters of the insulating medium at the device port where the leakage current failure occurs and re-perform the simulation until the leakage current failure does not occur at any of the device ports.

[0083] S52. If the breakdown failure does not occur, proceed to step S53. Otherwise, install the surge protector on the device port that sent the breakdown failure and re-perform the simulation and adjust the surge protector parameters until the breakdown failure does not occur on any device port.

[0084] S53. Determine the parameters of the insulating medium in step S51 and the parameters of the surge protector in step S52, and implement them accordingly in the actual electrical system.

[0085] Further, the surge protector parameter adjustment includes adjusting the specifications of the surge protector, increasing the number of the surge protector, or adjusting the location of the surge protector.

[0086] As can be seen from the above description, by using a flow method to integrate the two important safety designs of insulation coordination and lightning protection into simulation, checking the initial electrical system that meets the requirements can reduce the use of enhanced insulation and repeated surge protectors, thereby effectively reducing costs while ensuring safety.

[0087] Please refer to Figure 7 An electrical system surge test modeling terminal, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned electrical system surge test modeling method when executing the computer program.

[0088] As can be seen from the above description, the beneficial effects of the present application are that based on the same technical concept, in combination with the above-mentioned electrical system surge test modeling method, an electrical system surge test modeling terminal is provided, which simulates the response behavior of low-voltage electrical system lightning surge interference by establishing lightning surge interference source models, device port and impulse voltage conduction path models, device insulation coordination models, and lightning protection device models, realizes flow evaluation of lightning protection measures and lightning protection device selection for the system, effectively analyzes whether the lightning protection measures of the electrical system after being connected to the power distribution network are appropriate, whether the main facility devices will be damaged after being struck by lightning, whether significant safety consequences will be caused, and whether the selection of lightning protection devices is reasonable, avoids damage to the devices in actual tests, and provides a basis for the design of electrical system lightning protection.

[0089] The electrical system surge test modeling method and terminal provided by the present application are mainly applied to the insulation coordination and lightning protection design scenarios of low-voltage electrical system devices, and specific embodiments will be described below:

[0090] Please refer to Figure 1 Embodiment one of the present application is:

[0091] An electrical system surge test modeling method, as Figure 1 shown, comprising the steps of:

[0092] S1, a common mode conduction method is used to establish a lightning surge interference source model for the electric waves of induced lightning.

[0093] S2, identify the devices in the electrical system that are susceptible to lightning overvoltage or overcurrent, their sensing position ports, and the conduction path of impulse voltage, and establish a device port and impulse voltage conduction path model.

[0094] S3, establishing a device insulation coordination model for the insulation coordination of the identified induction position port of the device in the electrical system.

[0095] S4, establishing a lightning protection device model for the lightning protection device.

[0096] S5, simulating the lightning strike protection process of the electrical system based on the lightning surge interference source model, the device port and impulse voltage conduction path model, the device insulation coordination model and the lightning protection device model.

[0097] That is, in the embodiment, the response behavior of the lightning surge interference of the low-voltage electrical system is simulated by establishing the lightning surge interference source model, the device port and impulse voltage conduction path model, the device insulation coordination model and the lightning protection device model, the selection of lightning protection measures and lightning protection devices of the system is evaluated in a process, so as to effectively analyze whether the lightning protection measures of the electrical system after being connected to the power distribution network are appropriate, whether the main facility devices will be damaged after being struck by lightning, whether significant safety consequences will be caused, and whether the selection of lightning protection devices is reasonable, avoid damage to the devices in actual test, and provide a basis for the design of the lightning protection of the electrical system.

[0098] Please refer to Figures 2 to 6 , the second embodiment of the present application is:

[0099] A surge test modeling method for an electrical system, based on the above-mentioned first embodiment, in the embodiment, the common mode conduction method is used to establish a lightning surge interference source model for the lightning wave in step S1, and the parameters of the main lightning wave generated at the location of the electrical system can be adjusted, so that the degree of lightning surge interference source entering the electrical system interface through the common mode line can be simulated, and the specific steps are as follows:

[0100] S11, decomposing the lightning transient process of the induced lightning, using an exponential function to describe the process of the lightning passing through the lightning rod set by the building to produce overvoltage on the common ground network of the electrical system device and other buildings, and the induced lightning impulse generated by the lightning position down lead grounding to the common ground network of the grounding system at the induction position, when lightning occurs at the lightning position, the impulse voltage V P (t) is as follows formula (1):

[0101]

[0102] Where, R GND_i is the DC resistance of the grounding system from the lightning position to the induction position, i represents the count in the formula, I P1Where, I is the maximum lightning current at the lightning position, τ1 is the time constant of the lightning current rising at the lightning moment, τ2 is the time constant of the lightning current falling after the lightning, and k is a coefficient. The "lightning rod" is the process of lightning discharge by the lightning rod connected to the ground, i.e. the process of lightning current discharge through the lightning rod connected to the ground.

[0103] S12, obtaining the peak value of the maximum lightning current through lightning weather history data at the location of the electrical system.

[0104] S13, obtaining the direct current resistance R of the grounding system from the lightning position to the induction position through measurement or equivalent calculation GND_i。 As shown in Figure 2 , the grounding symbol position adds two annotations of the grounding point of the system, i.e. "lightning position down conductor grounding point" and "induction position grounding point", which can be known from Figure 2 that the lightning current path after the lightning rod is divided into two parts, I P1 part flows through the resistance R GND of the common grounding network composed of M series, reaches the "induction position grounding point"; the dynamic process of the voltage drop V P (t) generated by the resistance and the current flowing through all M segments of the common grounding network.

[0105] S14, obtaining the values of τ1 and τ2 according to the lightning current level at the induction position, specifically:

[0106] According to whether the installation position of the electrical system is inside or outside the building, the lightning current level is divided into two levels:

[0107] The lightning current level outside the building is defined as level one, and the time constants τ1 = 5-10 μs and τ2 = 100-350 μs are taken;

[0108] The lightning current level inside the building is defined as level two, and the time constants τ1 = 0.25-1.2 μs and τ2 = 50-100 μs are taken.

[0109] The value of the lightning strike time constant mainly depends on the intensity of the lightning strike. Lightning strike intensity outside buildings is generally higher than inside. Therefore, lightning current levels are classified according to the installation location of the electrical system. Those located outside the building are defined as Level 1, indicating severe lightning impact, thus the range of their two time constants is large. Those located inside the building are defined as Level 2, indicating slightly less severe lightning impact, thus the range of their two time constants is small. Within each level, it is generally divided into "first lightning strike" and "subsequent lightning strike," with the former generally stronger than the latter. Therefore, based on extensive lightning strike statistics, the time constants for Level 1 are defined as τ1 = 5–10 μs and τ2 = 100–350 μs, and for Level 2, τ1 = 0.25–1.2 μs and τ2 = 50–100 μs.

[0110] S15. Create an interference source V in the simulation tool. P The expression is given by formula (1), and based on formula (1), a lightning surge interference source model for the surge generator is established, as shown in formula (1). Figure 4 The voltage-time curve shown is Surge_Voltage, representing the voltage in a surge generator.

[0111] S16, Control the interference source V in the surge generator P The output resistance is such that its output current is between 0 and I. P1 Adjustment between them, such as Figure 4 The surge generator is shown with a current-time curve (Surge_Current). This embodiment uses a current-limiting voltage source to describe a surge energy pulse generated by a lightning strike; that is, the maximum current after a pulse hits the insulating medium (hereinafter referred to as "insulation coordination") is limited to I. P1 The Surge_Current curve represents the maximum current waveform produced when a pulse strikes an uninsulated conductor.

[0112] In this embodiment, a lightning surge interference source model of a surge generator is established, and the parameters of the main lightning waves generated at the location of the electrical system are adjustable, thereby simulating the extent to which lightning surge interference sources enter the electrical system interface through common-mode lines. Furthermore, if an electrical system in a common-ground network contains down conductors at more than one lightning strike location, then there are more than one lightning surge interference source model.

[0113] In this embodiment, step S2 specifically includes:

[0114] S21. Identify all equipment in the electrical system that is sensitive to lightning strikes. Among them, such as... Figure 3The sensitive equipment is identified after the lightning hits the building lightning rod. The power unit and the control unit in the electrical system connected to the building power distribution network and containing the power unit and the control unit are easily affected by overvoltage or overcurrent.

[0115] S22, identify the power port and the signal port of the equipment relative to the common ground network in the electrical system, specifically, according to the requirements of item 8 (immunity test requirements) in the standard GB / T 17799.2 "General standard for electromagnetic compatibility Immunity test in industrial environment" and the requirements of the equipment specification, identify the power port with direct current power input / output function and alternating current power input / output function and the signal port with signal transmission function.

[0116] S23, simulate all transmission paths according to the connection of the identified power port and signal port relative to different grounding points in the same induction position, and obtain the equipment port and impulse voltage transmission path model.

[0117] As shown in Figure 4 The simulation model established by Matlab / Simulink is shown. The connection point position between "DC bus" and "PCS DC protection" in the system is identified by step S22, which has a direct current power input / output port, Figure 3 The model is established for the port. At the same time, the model surge generator A has the characteristics established according to steps S11, S15 and S16, which is applied between the negative power line Conn2 of the DC bus and the grounding point GND in the same induction position, and also should be applied between the positive power line Conn1 and the grounding point GND. The arrow in the figure represents that the surge generator A simulates the Conn2-GND port. In addition, the "battery cabinet" is connected to the port through the "DC bus". Because the DC bus is a low resistance conductor, the pulse applied by the surge generator A acts on the Batt-position, which represents that there is a transmission path between the surge generator A and the positive and negative power lines Batt+, Batt- of the battery cabinet and the grounding point GND.

[0118] That is, the power unit and the control unit of the electrical system are easily affected by overvoltage and overcurrent, which will affect the safe operation of the equipment, so they are regarded as sensitive equipment; at the same time, the power port and the signal port of all equipment relative to the same common ground network in the electrical system may bear the impulse voltage generated by lightning, so these ports need to be identified, and then the transmission path of each port relative to different grounding points in the same induction position is simulated to establish the model, so as to simulate the lightning process.

[0119] At the same time, in this embodiment, step S3 is specifically:

[0120] S31, the device port contains an insulation coordination designed to withstand the impulse voltage in step S22, so that the port will not produce overvoltage breakdown or overcurrent damage. The insulation coordination model of the device is established based on the breakdown characteristics of the insulation medium:

[0121]

[0122] Wherein, R is the insulation resistance of the insulation medium, ρ1 is the resistivity of the insulation medium under normal conditions, d is the material thickness of the insulation medium, k1 and k2 are respectively the coefficients related to the ambient temperature and humidity of the insulation medium under normal conditions, ρ2 is the resistivity of the insulation medium under breakdown condition, E is the voltage field strength of the insulation medium, ε is the dielectric constant of the insulation medium, k3 and k4 are respectively the coefficients related to the ambient temperature and humidity of the insulation medium under breakdown condition.

[0123] S32, obtain ε of the insulation medium through the material manual, and measure k1, k2, k3 and k4 of the insulation medium through the test method, and substitute them into formula (2).

[0124] S33, define two failure modes of the insulation medium, leakage current failure and breakdown failure:

[0125] When the insulation resistance of the insulation medium ρ2d<R<R limit and E<εdk3k4 is the leakage current failure, and:

[0126]

[0127] Wherein, U N_max is the maximum working voltage of the insulation medium in the port, I safe is the safe leakage current, R limit is the safe insulation resistance limit value of the insulation medium, at this time the device has the risk of electric shock in the port.

[0128] When E≥εdk3k4 is the breakdown failure, at this time the device has the risk of damage in the port.

[0129] That is, the insulation coordination represents the voltage withstand capability of the insulation material, the insulation coordination model of the device is established based on the breakdown characteristics of the insulation medium, and the insulation coordination design of the port is ensured to withstand the impulse voltage, so that the port will not produce overvoltage breakdown or overcurrent damage; meanwhile, two failure modes including leakage current failure and breakdown failure are defined in the insulation coordination model of the device, so that it is convenient to analyze which failure in subsequent simulation.

[0130] Wherein, in the embodiment, step S4 is specifically:

[0131] S41, the surge protection device SPD is modeled by using the principle of controlled voltage source, so that the voltage protection level parameter Uk According to the current value output, the voltage protection level of the surge protector is reached, and the pressure-sensitive and clamping characteristics when the SPD acts are simulated as follows formula (4):

[0132]

[0133] Wherein, U in is the impulse voltage applied to both ends of the surge protector, U P is the voltage protection level of the surge protector, U res is the residual voltage after protection action, I in and I max are the current flowing through the surge protector and the maximum allowed current after protection action, respectively.

[0134] S42, the expression of the residual voltage is established, and U res is the function related to I in According to the specification manual of the SPD, N points are taken on the curve of U res -I in , and the expression of the residual voltage U res_N of the Nth point after piecewise linearization is as follows formula (5):

[0135] U res_N =A N +B N I in_N (5);

[0136] Wherein, A N and B N are the expression coefficients of the Nth point after linearization.

[0137] That is, the lightning protection device model of the surge protector is established using the controlled voltage source principle, and the voltage protection level parameter of the surge protector is output according to the current value, so as to simulate the pressure-sensitive and clamping characteristics when the surge protector acts.

[0138] Finally, in this embodiment, as shown in Figure 6 , step S5 is specifically:

[0139] S51, when no surge protector is set at the port of all devices, and the temperature of the insulating medium is outside-20-50℃ or the humidity is outside 0-95%, simulation is performed based on the lightning surge interference source model, the device port and the impulse voltage conduction path model, the device insulation coordination model and the lightning protection device model, if no leakage current failure occurs, it is considered that the port insulation medium of the electrical system meets the safety insulation requirement, then step S52 is entered; otherwise, the parameters of the insulation medium of the device port where the leakage current failure occurs are adjusted and the simulation is performed again until no leakage current failure occurs at all device ports.

[0140] If no breakdown failure occurs, it is considered that the electrical system can withstand the surge impact on the equipment caused by the surrounding lightning without installing lightning protection devices, and then step S53 is entered. Otherwise, a surge protection device (SPD) is installed at the port of the equipment that has breakdown failure, and simulation and SPD parameter adjustment are performed again until no breakdown failure occurs at all equipment ports. The SPD parameter adjustment includes adjusting the specifications of the SPD, increasing the number of SPDs, or adjusting the location of the SPD. For example, Figure 5 It is shown that when the BatVoltage_P port is added with an SPD, V P (SPD_Voltage) is clamped at about 4kV to meet the impulse withstand voltage requirement of the battery equipment port.

[0141] In step S53, the parameters of the insulating medium in step S51 and the parameters of the SPD in step S52 are determined and implemented in the actual electrical system.

[0142] That is, by using a process-based method, the important safety designs of insulation coordination and lightning protection are integrated into simulation and simulation to verify the initial electrical system that meets the requirements, which can reduce the use of enhanced insulation and repeated addition of surge protection devices, thereby effectively reducing costs while ensuring safety.

[0143] Please refer to Figure 7 Embodiment three of the present application is:

[0144] An electrical system surge test modeling terminal 1 includes a memory 2, a processor 3, and a computer program stored on the memory 2 and executable on the processor 3. When the processor 3 executes the computer program, the steps of the electrical system surge test modeling method in embodiment one or embodiment two are completed.

[0145] In summary, the present application provides an electrical system surge test modeling method and terminal, which focuses on establishing design basis for surge interference and port protection under lightning conditions. On the one hand, modeling simulation method is used to obtain main theoretical support, which makes up for the design result difference caused by random test environment and conditions when using the test method. On the other hand, the process-based method integrates the two important safety designs of insulation coordination and lightning protection into the development process to identify sensitive and safety-related equipment. By using simulation method to verify the initial system that meets the requirements, the use of enhanced insulation and repeated addition of SPDs can be reduced, thereby reducing costs.

[0146] The above is only an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent transformation or direct or indirect application in related technical fields based on the content of the specification and drawings is also included in the patent protection scope of the present application.

Claims

1. A method of modeling a surge test of an electrical system, the method comprising: The method comprises the steps of: S1, using a common mode conduction method to establish a lightning surge interference source model for the electric wave of induced lightning, so that the parameters of the lightning wave generated at the location of the electrical system are adjustable, and the degree of simulation of the lightning surge interference source entering the electrical system interface through the common mode line is simulated; S2, identifying the devices in the electrical system that are susceptible to lightning overvoltage or overcurrent, the sensing position ports and the conduction paths of the impulse voltage, and establishing a device port and impulse voltage conduction path model; S3, establishing a device insulation coordination model for the sensing position ports of the devices identified in the electrical system; S4, establishing a lightning protection device model for the lightning surge protection device, specifically: S41, using the principle of controlled voltage source to establish the lightning protection device model of the surge protector, so that the voltage protection level parameter U k According to the current value output, the lightning protection device model is as follows formula (4): wherein U in is the impulse voltage applied across the surge protector, U P is the voltage protection level of the surge protector, U res is the residual voltage after the protection action, I in and I max are the current flowing through the surge protector and the maximum allowed current, respectively, after the protection action; S42, U res -I in N points of the curve of U res_N The expression of U is as follows formula (5): U res_N = A N + B N I in_N (5); where A N and B N are the linearized Nth point expression coefficients.

2. The method of claim 1, wherein, The step S1 is specifically: S11, decomposing the lightning transient process of induced lightning, using an exponential function to describe the process of overvoltage generated by lightning on the common ground network of the electrical system equipment and other buildings after the lightning strikes the lightning rod installed on the building, and the common ground network of the grounding system at the induced position where the down conductor of the lightning strike position is grounded to the electrical system equipment is struck by lightning, when the lightning strikes the lightning position, the impulse voltage generated at the induced position is as follows Formula (1): wherein R GND_i is the direct current resistance of the grounding system from the lightning strike position to the inductive position, i represents the count in the formula, I P1 is the maximum lightning current at the lightning strike position to the shunt current on the common ground network of the electrical system, τ1 is the time constant of the lightning current rise at the moment of lightning, τ2 is the time constant of the current drop after lightning, and k is a coefficient. S12, obtaining the peak value of the maximum lightning current through the lightning meteorological historical data at the location of the electrical system; S13, obtaining the ground system direct current resistance R from the lightning strike position to the induction position by measurement or equivalent calculation GND_i ; S14, obtaining the values of τ1 and τ2 according to the lightning current level of the induced position; S15, establishing an interference source V in the simulation tool P The expression is shown in formula (1), and the lightning surge interference source model of the surge generator is established based on formula (1). S16, control the output resistance of the interference source V in the surge generator, so that the output current is adjusted between 0 to I P . P1 .

3. The method of claim 2, wherein, The step S14 is specifically: According to whether the installation position of the electrical system is located inside or outside the building, it is divided into two lightning current levels; The lightning current level located outside the building is defined as level one, and the time constants τ1=5-10 μs and τ2=100-350 μs are taken; The lightning current level located inside the building is defined as level two, and the time constants τ1=0.25-1.2 μs and τ2=50-100 μs are taken.

4. The method of claim 2, wherein, The step S2 is specifically: S21, identifying all devices in the electrical system that are sensitive to lightning impulse; S22, identifying the power ports and signal ports of all devices relative to a common ground network in the electrical system; S23, according to the connection of the identified power ports and signal ports relative to different grounding points and the induced position, simulating all transmission paths to obtain a device port and impulse voltage conduction path model.

5. The method of claim 4, wherein, The step S21 is specifically: After the lightning strikes the lightning rod of the building, the components inside the power units and control units in the electrical system connected to the power distribution network of the building and containing the power units and control units are identified as sensitive devices, which are susceptible to overvoltage or overcurrent; The step S22 is specifically: According to the requirements of standard GB / T 17799.2 and the device specification, the power ports with direct current power input / output function and alternating current power input / output function and the signal ports with signal transmission function are identified.

6. The method of claim 4, wherein, The step S3 is specifically: S31, establishing a device insulation coordination model based on the breakdown characteristics of the insulating medium: Wherein, R is the insulation resistance of the insulation medium, ρ1 is the resistivity of the insulation medium under normal conditions, d is the material thickness of the insulation medium, k1 and k2 are respectively the coefficients of the resistivity related to the ambient temperature and humidity of the insulation medium under normal conditions, ρ2 is the resistivity of the insulation medium under breakdown conditions, E is the voltage field strength borne by the insulation medium, ε is the dielectric constant of the insulation medium, k3 and k4 are respectively the coefficients of the voltage field strength related to the ambient temperature and humidity of the insulation medium under breakdown conditions. S32, obtaining ε of the insulation medium through a material manual, and obtaining k1, k2, k3 and k4 of the insulation medium through a test method, and substituting into formula (2); S33, defining two failure modes of the insulation medium, i.e. the leakage current failure and the breakdown failure: when the insulation resistance of the insulation medium ρ2d < R < R limit and E < εdk3k4is the leakage current failure, then: wherein U N_max is the maximum operating voltage of the port in which the insulating medium is located, I safe is the safety leakage current, R limit is the safety insulation resistance limit value of the insulating medium; When E≥εdk3k4, it is the breakdown failure.

7. The method of claim 6, wherein, The step S4 further comprises: S5, simulating the lightning strike protection process of the electrical system based on the lightning surge interference source model, the device port and impulse voltage conduction path model, the device insulation coordination model and the lightning protection device model.

8. The method of claim 7, wherein, The step S5 is specifically: S51, when no surge protection device is arranged at the port of all devices, and the temperature of the insulation medium is outside -20-50℃ or the humidity is outside 0-95%, simulating based on the lightning surge interference source model, the device port and impulse voltage conduction path model, the device insulation coordination model and the lightning protection device model, if the leakage current failure does not occur, entering step S52, otherwise adjusting the parameters of the insulation medium of the device port where the leakage current failure occurs and re-simulating until the leakage current failure does not occur in all device ports; S52, if the breakdown failure does not occur, entering step S53, otherwise installing the surge protection device at the device port where the breakdown failure occurs and re-simulating and adjusting the parameters of the surge protection device until the breakdown failure does not occur in all device ports; S53, determining the parameters of the insulation medium in step S51 and the parameters of the surge protection device in step S52, and corresponding implementation in the actual electrical system.

9. The method of claim 8, wherein, The surge protection device parameter adjustment comprises adjusting the specifications of the surge protection device, increasing the number of the surge protection device or adjusting the position of the surge protection device.

10. An electrical system surge test modeling terminal, characterized by, The computer program product comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the electrical system surge test modeling method in any one of claims 1-9 when executing the computer program.

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