Electrical system surge test modeling method and terminal

Abstract

According to the electrical system surge test modeling method and the terminal provided by the invention, the lightning surge interference source model, the equipment port and impulse voltage conduction path model, the equipment insulation cooperation model and the lightning protection device model are established to perform simulation test on the response behavior of the lightning surge interference of the low-voltage electrical system; according to the invention, flow evaluation is carried out on selection of lightning protection measures and lightning protection devices of the system so as to analyze whether the lightning protection measures are appropriate after an electrical system is connected to a power distribution network, whether main facilities and equipment are damaged after lightning stroke, whether major safety consequences are generated, and whether selection of the lightning protection devices is reasonable. Damage to equipment in an actual test is avoided, and a basis is provided for lightning protection design of an electrical system; and a lightning protection device model of the surge protector is established by using a controlled voltage source principle, and voltage protection level parameters of the surge protector are output according to a current value, so that the voltage-sensitive and clamping characteristics of the real surge protector during action are simulated.

Description

[0001] This case is a divisional application based on the invention patent with application date of September 4, 2024, application number 202411231521.8, and name “A method and terminal for modeling and simulating surge tests in electrical systems” as the parent case. Technical Field

[0002] The present invention relates to the technical field of power systems, and in particular to an electrical system surge test modeling method and a terminal. Background Art

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

[0004] The integration of many DC power generation equipment and low-voltage distribution networks, especially the connection of electrochemical energy storage batteries and photovoltaic power generation equipment to the distribution network, makes the lightning protection facilities and line lightning protection level built for the AC distribution network insufficient to protect the newly added equipment. The harmful consequences of DC lines being struck by lightning are also different from those of AC lines. This makes it difficult to analyze whether the lightning protection measures after the electrical system is connected to the distribution network are appropriate, whether the main facilities and equipment will be damaged after being struck by lightning, whether there will be major safety consequences, and whether the selection of lightning protection devices is reasonable. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an electrical system surge test modeling method and terminal, so that the electrical system lightning protection process can be quickly evaluated, damage to the equipment in actual testing can be avoided, and the design of electrical system lightning protection can be based on a basis.

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

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

[0008] S1. Use the common mode conduction method to establish a lightning surge interference source model for the induced lightning waves, so that the parameters of the lightning waves generated at the location of the electrical system can be adjusted, simulating the extent to which the lightning surge interference source enters the electrical system interface through the common mode line;

[0009] S2. Identify the equipment in the electrical system that is susceptible to lightning overvoltage or overcurrent, its induction location ports, and the conduction path of the impulse voltage, and establish a model of the equipment port and the impulse voltage conduction path;

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

[0011] S4. Establish a lightning protection device model for the lightning surge protection device, specifically:

[0012] S41, using the controlled voltage source principle to establish a lightning protection device model of the surge protector, so that the voltage protection level parameter U of the surge protector k According to the current value output, the lightning protection device model is as follows:

[0013]

[0014] Among them, 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 respectively the current flowing through the surge protector after protection action and the maximum allowable current;

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

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

[0017] Among them, A N and B N is the coefficient of the Nth point expression after linearization.

[0018] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0019] An electrical system surge test modeling terminal comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned electrical system surge test modeling method are implemented.

[0020] The beneficial effects of the present invention are as follows: a method and a terminal for modeling surge test of an electrical system are provided, which are used to simulate and test the response behavior of lightning surge interference of a low-voltage electrical system by establishing a lightning surge interference source model, an equipment port and impulse voltage conduction path model, an equipment insulation coordination model and a lightning protection device model, so as to realize a process-based evaluation of the lightning protection measures and the selection of lightning protection devices of the system, so as to effectively analyze whether the lightning protection measures after the electrical system is connected to the distribution network are appropriate, whether the main facilities and equipment will be damaged after being struck by lightning, whether there will be major safety consequences, and whether the selection of lightning protection devices is reasonable, so as to avoid damage to the equipment in actual testing, and provide a basis for the design of lightning protection of the electrical system; at the same time, a lightning protection device model of a surge protector is established using the principle of a controlled voltage source, and the voltage protection level parameter of the surge protector is output according to the current value, so as to simulate the voltage-sensitive and clamping characteristics of the real surge protector when it is in action. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an overall flow chart of an electrical system surge test modeling method according to an embodiment of the present invention;

[0022] Figure 2 This is a system architecture diagram of a lightning rod in a building struck by lightning in an embodiment of the present invention;

[0023] Figure 3 The schematic diagrams of the four models established by MatLab / Simulink in the embodiments of the present invention are shown in FIG.

[0024] Figure 4 The relationship curves between voltage and current and time in the surge generator during the simulation of four models are established in the embodiment of the present invention;

[0025] Figure 5 The relationship curves between the voltage and current of the surge generator and the surge protector and time during the simulation of four models in the embodiment of the present invention and the relationship curve between the surge common mode voltage acting on Batt and the ground point FND at the same sensing position and time are established;

[0026] Figure 6 A specific flow chart of an electrical system surge test modeling method in an embodiment of the present invention;

[0027] Figure 7 The present invention is a schematic structural diagram of an electrical system surge test modeling terminal according to an embodiment of the present invention.

[0028] Description of labels:

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

[0030] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

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

[0032] S1. Use the common mode conduction method to establish a lightning surge interference source model for the induced lightning waves;

[0033] S2. Identify the equipment in the electrical system that is susceptible to lightning overvoltage or overcurrent, its induction location ports, and the conduction path of the impulse voltage, and establish a model of the equipment port and the impulse voltage conduction path;

[0034] S3, establishing an equipment insulation coordination model for the insulation coordination of the sensing position port of the equipment in the identified electrical system;

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

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

[0037] From the above description, it can be seen that the beneficial effects of the present invention are: providing an electrical system surge test modeling method, simulating the response behavior of lightning surge interference in a low-voltage electrical system by establishing a lightning surge interference source model, an equipment port and impulse voltage conduction path model, an equipment insulation coordination model and a lightning protection device model, and realizing a process-based evaluation of the system's lightning protection measures and the selection of lightning protection devices, so as to effectively analyze whether the lightning protection measures after the electrical system is connected to the distribution network are appropriate, whether the main facilities and equipment will be damaged after being struck by lightning, whether there will be major safety consequences, and whether the selection of lightning protection devices is reasonable, so as to avoid damage to the equipment in actual testing and provide a basis for the design of lightning protection for the electrical system.

[0038] Furthermore, the step S1 is specifically as follows:

[0039] S11. Decompose the transient process of induced lightning strikes, use an exponential function to describe the process of overvoltage generated by lightning on the common ground network of electrical system equipment and other buildings after lightning is connected to the lightning rod installed in the building, and ground the down conductor at the lightning strike location to the common ground network of the grounding system where the induction location of the induced lightning strike of the electrical system equipment is located. When lightning strikes at the lightning strike location, the impulse voltage generated at the induction location is as follows:

[0040]

[0041] Among them, R GND_i is the DC resistance of the grounding system from the lightning strike location to the sensing location, i represents the count in the formula, and I P1 is the shunt current of the maximum lightning current at the lightning strike location to the common ground network of the electrical system, τ1 is the time constant of the instantaneous current rise of the lightning strike, τ2 is the time constant of the current drop after the lightning strike, and k is the coefficient;

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

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

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

[0045] S15. Establish interference source V in simulation tool P , so that its expression is as 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 interference source V in the surge generator P The output resistance is set to make the output current between 0 and I P1 Adjust between.

[0047] From the above description, it can be seen that by establishing a lightning surge interference source model of a surge generator and making the parameters of the main lightning waves generated at the location of the electrical system adjustable, the extent to which the lightning surge interference source enters the electrical system interface through the common mode line is simulated.

[0048] The step S14 is specifically as follows:

[0049] There are two lightning current levels depending on whether the electrical system is installed inside or outside the building;

[0050] The lightning current level outside the building is defined as level 1, and the time constants are τ1=5-10μs and τ2=100-350μs;

[0051] The lightning current level in the building is defined as level 2, with time constants τ1 = 0.25-1.2 μs and τ2 = 50-100 μs.

[0052] From the above description, it can be seen that the lightning current level is classified according to the installation location of the electrical system. The one located outside the building is level one, which means that it is severely affected by lightning, so the setting range of the two time constants is large, while the one located inside the building is level two, which means that it is slightly less affected by lightning, so the setting range of the two time constants is small.

[0053] The step S2 is specifically as follows:

[0054] S21. Identify all equipment in the electrical system that is sensitive to lightning strikes;

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

[0056] S23. According to the identified connections between the power port and the signal port relative to different grounding points and the sensing position, all transfer paths are simulated to obtain a device port and impulse voltage conduction path model.

[0057] The step S21 is specifically as follows:

[0058] After lightning strikes the lightning rod of the building, the components inside the power units and control units in the electrical system connected to the building's power distribution network and containing the power units and control units that are susceptible to overvoltage or overcurrent are identified as sensitive equipment;

[0059] The step S22 is specifically as follows:

[0060] According to the requirements of standard GB / T 17799.2 and the equipment specification, identify the power ports with DC power input / output function and AC power input / output function and the signal ports with signal transmission function.

[0061] From the above description, it can be seen that the power unit and 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 devices; at the same time, the power ports and signal ports of all devices in the electrical system relative to the same common ground network are likely to be subjected to the impulse voltage generated by lightning strikes, so these ports need to be identified, and then a model is established by simulating the transmission path of each port relative to different grounding points and the same sensing position, so as to simulate the lightning strike process.

[0062] The step S3 is specifically as follows:

[0063] S31. Establish equipment insulation coordination model based on insulation dielectric breakdown characteristics:

[0064]

[0065] Wherein, R is the insulation resistance of the insulating medium, ρ 1is the resistivity of the insulating medium under normal conditions, d is the material thickness of the insulating medium, k 1 and k 2 are the coefficients of the resistivity under normal conditions related to the ambient temperature and humidity of the insulating medium, ρ 2 is the resistivity of the insulating medium under breakdown conditions, E is the voltage field strength borne by the insulating medium, ε is the dielectric constant of the insulating medium, k 3 and k 4 are coefficients related to the voltage field strength under breakdown conditions and the ambient temperature and humidity of the insulating medium;

[0066] S32. Obtain the ε of the insulating medium through the material manual, and measure the k of the insulating medium through the test method. 1 , k 2 , k 3 and k 4 , and substitute it into formula (2);

[0067] S33, defining two failure modes of the insulating medium: leakage current failure and breakdown failure:

[0068] When the insulation resistance ρ of the insulating medium 2 d <R<R limit And E<εdk 3 k 4 For the leakage current failure, then:

[0069]

[0070] Among them, U N_max is the maximum working voltage of the port where 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;

[0071] When E ≥ εdk 3 k 4 When is the breakdown failure.

[0072] From the above description, it can be seen that insulation coordination refers to the voltage resistance capability of the insulating material. The equipment insulation coordination model is established based on the insulation medium breakdown characteristics to ensure that the equipment port has an insulation coordination design that can withstand the impulse voltage so that the port will not produce overvoltage breakdown or overcurrent damage. At the same time, two failure modes including leakage current failure and breakdown failure are defined in the equipment insulation coordination model to facilitate subsequent simulation analysis of the type of failure.

[0073] The step S4 is specifically as follows:

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

[0075]

[0076] Among them, 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 respectively the current flowing through the surge protector after protection action and the maximum allowable current;

[0077] S42, U res -I in Take N points on the curve and get the residual voltage U at the Nth point after piecewise linearization. res_N The expression of 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 is the coefficient of the Nth point expression after linearization.

[0080] From the above description, it can be seen that the lightning protection device model of the surge protector is established using the controlled voltage source principle and the voltage protection level parameters of the surge protector are output according to the current value, so as to simulate the voltage-sensitive and clamping characteristics of the real surge protector when it is in action.

[0081] The step S5 is specifically as follows:

[0082] S51. When the surge protector is not provided at the ports of all devices, 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, the process proceeds to step S52. Otherwise, the parameters of the insulating medium of the device port where the leakage current failure occurs are adjusted and the simulation is performed again until the leakage current failure does not occur at all 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-simulate and adjust the parameters of the surge protector until the breakdown failure does not occur on all device ports;

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

[0085] Furthermore, the surge protector parameter adjustment includes adjusting the specification of the surge protector, increasing the number of the surge protectors, or adjusting the position of the surge protectors.

[0086] From the above description, it can be seen that by using a process-based approach to integrate the two important safety designs of insulation coordination and lightning protection into the simulation and verifying that the initial electrical system meets the requirements, it is possible to reduce the need to reinforce insulation and repeatedly increase the use of 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 in the memory and executable on the processor, wherein when the processor executes the computer program, the steps in the electrical system surge test modeling method as described above are implemented.

[0088] From the above description, it can be seen that the beneficial effects of the present invention are: based on the same technical concept, in conjunction with the above-mentioned electrical system surge test modeling method, an electrical system surge test modeling terminal is provided, by establishing a lightning surge interference source model, an equipment port and impulse voltage conduction path model, an equipment insulation coordination model and a lightning protection device model to simulate the response behavior of the low-voltage electrical system lightning surge interference, and realize a process-based evaluation of the system's lightning protection measures and lightning protection device selection, so as to effectively analyze whether the lightning protection measures after the electrical system is connected to the distribution network are appropriate, whether the main facilities and equipment will be damaged after being struck by lightning, whether it will have major safety consequences, and whether the selection of lightning protection devices is reasonable, so as to avoid damage to the equipment in actual testing and provide a basis for the design of lightning protection for the electrical system.

[0089] The present invention provides an electrical system surge test modeling method and terminal, which are mainly used in insulation coordination and lightning protection design scenarios of low-voltage electrical system equipment, and are specifically described below in conjunction with specific embodiments:

[0090] Please refer to Figure 1 , Embodiment 1 of the present invention is:

[0091] A method for modeling surge testing of electrical systems, such as Figure 1As shown, the steps include:

[0092] S1. Use the common mode conduction method to establish a lightning surge interference source model for the induced lightning waves.

[0093] S2. Identify the equipment in the electrical system that is susceptible to lightning overvoltage or overcurrent, its induction location ports, and the conduction path of the impulse voltage, and establish a model of the equipment port and impulse voltage conduction path.

[0094] S3. Establishing an equipment insulation coordination model for the insulation coordination of the sensing position port of the equipment in the identified electrical system.

[0095] S4. Establish a lightning protection device model for the lightning surge protection device.

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

[0097] That is, in this embodiment, by establishing a lightning surge interference source model, an equipment port and impulse voltage conduction path model, an equipment insulation coordination model and a lightning protection device model, the response behavior of the low-voltage electrical system lightning surge interference is simulated, and a process-based evaluation of the system's lightning protection measures and the selection of lightning protection devices is achieved, so as to effectively analyze whether the lightning protection measures after the electrical system is connected to the distribution network are appropriate, whether the main facilities and equipment will be damaged after being struck by lightning, whether there will be major safety consequences, and whether the selection of lightning protection devices is reasonable, so as to avoid damage to the equipment in actual testing and provide a basis for the design of lightning protection for the electrical system.

[0098] Please refer to Figures 2 to 6 , Embodiment 2 of the present invention is:

[0099] A method for modeling surge test of an electrical system. Based on the above-mentioned embodiment 1, in this embodiment, in step S1, a common mode conduction method is used to establish a lightning surge interference source model for the electric wave of induced lightning, and the parameters of the main lightning waves generated at the location of the electrical system can be adjusted, so as to simulate the degree to which the lightning surge interference source enters the electrical system interface through the common mode line. The specific steps are:

[0100] S11. Decompose the transient process of induced lightning strikes, use exponential functions to describe the process of overvoltage generated by lightning on the common ground network of electrical system equipment and other buildings after lightning is connected to the lightning rod installed in the building, and connect the down conductor at the lightning strike location to the common ground network of the grounding system where the induction location of the electrical system equipment is located. When lightning strikes at the lightning strike location, the impulse voltage V generated at the induction location is P (t) is as follows:

[0101]

[0102] Among them, R GND_i is the DC resistance of the grounding system from the lightning strike location to the sensing location, i represents the count in the formula, I P1 is the shunt current of the maximum lightning current at the lightning strike location to the common ground network of the electrical system, τ1 is the time constant of the instantaneous current rise of the lightning strike, τ2 is the time constant of the current drop after the lightning strike, and k is the coefficient. Among them, "lightning termination" is the process of lightning discharge to the lightning rod (also known as lightning arrester) installed on the building, that is, the process of lightning current discharge through the lightning rod connected to the ground.

[0103] S12. Obtain the peak value of the maximum lightning current through the historical lightning meteorological data at the location of the electrical system.

[0104] S13. Obtain the DC resistance R of the grounding system from the lightning strike location to the induction location by measurement or equivalent calculation. GND_i。 like Figure 2 As shown in the figure, two annotations for the system grounding points are added to the grounding symbol position, namely "grounding point of down conductor at lightning strike position" and "grounding point at induction position". Figure 2 It can be seen that the lightning current path after lightning is divided into two parts, I P1 The part passes through the resistor R in the common ground network composed of a total of M segments in series GND , reaching the "sensing position grounding point"; the current flows through the resistance of all M segments of the common ground network and the voltage drop generated is V P (t).

[0105] S14. According to the lightning current level at the sensing position, the values ​​of τ1 and τ2 are obtained, which are specifically:

[0106] There are two lightning current levels depending on whether the electrical system is installed inside or outside a building:

[0107] The lightning current level outside the building is defined as level 1, with time constants τ1 = 5 ~ 10μs, τ2 = 100 ~ 350μs;

[0108] The lightning current level inside a building is defined as level two, with time constants τ1 = 0.25 ~ 1.2 μs and τ2 = 50 ~ 100 μs.

[0109] That is, the value of the lightning time constant mainly depends on the intensity of the lightning strike. The intensity of lightning strikes outside buildings is generally higher than that inside buildings. Therefore, the lightning current level is classified according to the installation location of the electrical system. The one outside the building is defined as level one, indicating that it is severely affected by lightning strikes, so the setting range of the two time constants is large, while the one inside the building is defined as level two, indicating that it is slightly less affected by lightning strikes, so the setting range of the two time constants is small. In each level, it is generally divided into "first lightning strike" and "subsequent lightning strikes", and the former is generally stronger than the latter. Therefore, based on extensive lightning strike statistical data, the time constants of level one are defined as τ1=5~10μs, τ2=100~350μs, and the time constants of level two are defined as τ1=0.25~1.2μs, τ2=50~100μs.

[0110] S15. Establish interference source V in simulation tool P , so that its expression is as shown in formula (1), and based on formula (1), the lightning surge interference source model of the surge generator is established, that is, Figure 4 The relationship curve between the voltage and time in the surge generator is shown as Surge_Voltage.

[0111] S16, control the interference source V in the surge generator P The output resistance is set to make the output current between 0 and I P1 Adjust between Figure 4 The relationship curve Surge_Current between the current and time in the surge generator is shown. In this embodiment, a current-limited voltage source is used 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 shows the maximum current waveform generated when a pulse hits a conductor without any insulation.

[0112] That is, in this embodiment, by establishing a lightning surge interference source model of a surge generator and making the parameters of the main lightning waves generated at the location of the electrical system adjustable, the extent to which the lightning surge interference source enters the electrical system interface through the common mode line is simulated. In addition, when a common ground network where a certain electrical system is located contains more than one lightning strike location down conductor, there is more than one lightning surge interference source model.

[0113] In this embodiment, step S2 is specifically as follows:

[0114] S21. Identify all equipment in the electrical system that is sensitive to lightning strikes. Figure 3The figure shows the situation after lightning strikes the lightning rod of the building. After lightning strikes the lightning rod of the building, the components inside the power units and control units in the electrical system connected to the building's power distribution network and containing the power units and control units that are susceptible to overvoltage or overcurrent are identified as sensitive equipment.

[0115] S22. Identify the power ports and signal ports of all devices in the electrical system that are connected to a common ground network. Specifically, identify the power ports with DC power input / output function and AC power input / output function and the signal ports with signal transmission function in accordance with Item 8 (Immunity test requirements) of GB / T 17799.2 "Electromagnetic compatibility general standard for immunity test in industrial environment" and the requirements of the equipment specification.

[0116] S23. According to the connection between the identified power port and the signal port relative to different grounding points and the sensing position, all the transmission paths are simulated to obtain a device port and impulse voltage conduction path model.

[0117] Among them, Figure 4 The simulation model established by Matlab / Simulink is shown. The connection point between the "DC bus" and the "PCS DC protection" in the system is identified through step S22. It has a DC power input / output port. Figure 3 It is a model established for this port. At the same time, the model surge generator A has the characteristics established according to steps S11, S15 and S16, and is applied between the negative power line Conn2 of the DC bus and the grounding point GND at the induction position, and should also be applied between the positive power line Conn1 and GND. The arrow in the figure indicates 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, indicating that for the surge generator A, there is a transmission path between the positive and negative power lines Batt+ and Batt- of the battery cabinet and the grounding point GND.

[0118] That is, the power unit and 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 devices; at the same time, the power ports and signal ports of all devices in the electrical system relative to the same common ground network are likely to be subjected to the impulse voltage generated by lightning strikes, so these ports need to be identified, and then a model is established by simulating the transmission path of each port relative to different grounding points and the same sensing position, so as to simulate the lightning strike process.

[0119] Meanwhile, in this embodiment, step S3 is specifically as follows:

[0120] S31. The device port includes an insulation coordination design to withstand the impulse voltage in step S22, so that the port will not be damaged by overvoltage breakdown or overcurrent. The device insulation coordination model is established based on the insulation medium breakdown characteristics:

[0121]

[0122] Where R is the insulation resistance of the insulating medium, ρ1 is the resistivity of the insulating medium under normal conditions, d is the material thickness of the insulating medium, and k 1 and k 2 are the coefficients of the resistivity under normal conditions related to the ambient temperature and humidity of the insulating medium, ρ2 is the resistivity of the insulating medium under breakdown conditions, E is the voltage field strength borne by the insulating medium, ε is the dielectric constant of the insulating medium, and k 3 and k 4 are the coefficients of the voltage field strength under breakdown conditions related to the ambient temperature and humidity of the insulating medium.

[0123] S32. Obtain the ε of the insulating medium through the material manual and measure the k of the insulating medium through the test method. 1 , k 2 , k 3 and k 4 , and substitute it into formula (2).

[0124] S33. Define two failure modes of insulating medium: leakage current failure and breakdown failure:

[0125] When the insulation resistance of the insulating medium is ρ2d <R<R limit And E<εdk 3 k 4 If it is a leakage current failure, then:

[0126]

[0127] Among them, U N_max is the maximum working voltage of the port where the insulating medium is located, I safe is the safety leakage current, R limit This is the safe insulation resistance limit of the insulating medium. At this point, there is a risk of electric shock to personnel at this port of the device.

[0128] When E≥εdk3k4, it is a breakdown failure, and the device is in danger of being damaged at this port.

[0129] That is, insulation coordination refers to the voltage resistance capability of insulating materials. An insulation coordination model of equipment is established based on the breakdown characteristics of insulating media to ensure that the equipment port has an insulation coordination design that can withstand impulse voltage so that the port will not produce overvoltage breakdown or overcurrent damage. At the same time, two failure modes, including leakage current failure and breakdown failure, are defined in the equipment insulation coordination model to facilitate subsequent simulation analysis of what type of failure it is.

[0130] In this embodiment, step S4 is specifically as follows:

[0131] S41. Use the controlled voltage source principle to establish a lightning protection device model for the surge protector SPD, so that the voltage protection level parameter U k According to the current value output, the voltage-sensitive and clamping characteristics when simulating the real SPD action are achieved. The lightning protection device model is as follows (4):

[0132]

[0133] Among them, 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 They are respectively the current flowing through the surge protector after protection action and the maximum allowable current.

[0134] S42. Establish the expression of residual voltage. After SPD protection is activated, U res isI in According to the SPD specification manual, the U res -I in Take N points on the curve and get the residual voltage U at the Nth point after piecewise linearization. res_N The expression of is as follows formula (5):

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

[0136] Among them, A N and B N is the coefficient of the Nth point expression 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 parameters of the surge protector are output according to the current value, so as to simulate the voltage-sensitive and clamping characteristics of the real surge protector when it is in action.

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

[0139] S51. When no surge protector is installed at the ports of all devices, 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 no leakage current failure occurs, it is considered that the port insulating medium of the electrical system meets the safety insulation requirements, and step S52 is entered; otherwise, the parameters of the insulating 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] S52: If no breakdown failure occurs, it is considered that the electrical system can withstand the surge impact of surrounding lightning strikes on the equipment without installing lightning protection devices, and then enter step S53. Otherwise, a surge protector SPD is installed on the device port that sends the breakdown failure, and the simulation and surge protector parameter adjustment are re-performed until no breakdown failure occurs on all device ports. The surge protector parameter adjustment includes adjusting the specifications of the surge protector, increasing the number of surge protectors, or adjusting the location of the surge protector. Figure 5 It shows that when SPD is added to the BatVoltage_P port, V P (SPD_Voltage) is clamped at around 4kV to meet the impulse withstand voltage requirement of the battery device port.

[0141] S53, determining the parameters of the insulating medium in step S51 and the parameters of the surge protector in step S52, and implementing them accordingly in an actual electrical system.

[0142] That is, using a process-based approach to integrate the two important safety designs of insulation coordination and lightning protection into the simulation, and verifying that the initial electrical system meets the requirements, can reduce the need to reinforce insulation and repeatedly increase the use of surge protectors, thereby effectively reducing costs while ensuring safety.

[0143] Please refer to Figure 7 , Embodiment 3 of the present invention is:

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

[0145] In summary, the electrical system surge test modeling method and terminal provided by the present invention focus on establishing the design basis for surge interference and port protection when lightning strikes the device port. On the one hand, the modeling and simulation method is used to obtain the main theoretical support to make up for the shortcomings such as large differences in design results caused by the randomness of the test environment and conditions when using the actual measurement method; on the other hand, the two important safety designs of insulation coordination and lightning protection are integrated into the development process by a process-based method to identify sensitive and safety-related equipment; by verifying the initial system that meets the requirements through the simulation method, it is possible to reduce the need to strengthen insulation and repeatedly increase the use of SPD, thereby reducing costs.

[0146] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for modeling surge testing of an electrical system, characterized in that: Includes steps: S1. Use the common mode conduction method to establish a lightning surge interference source model for the induced lightning waves, so that the parameters of the lightning waves generated at the location of the electrical system can be adjusted, simulating the extent to which the lightning surge interference source enters the electrical system interface through the common mode line; S2. Identify the equipment in the electrical system that is susceptible to lightning overvoltage or overcurrent, its induction location ports, and the conduction path of the impulse voltage, and establish a model of the equipment port and the impulse voltage conduction path; S3, establishing an equipment insulation coordination model for the insulation coordination of the sensing position port of the equipment in the identified electrical system; S4. Establish a lightning protection device model for the lightning surge protection device, specifically: S41, using the controlled voltage source principle to establish a lightning protection device model of the surge protector, so that the voltage protection level parameter U of the surge protector k According to the current value output, the lightning protection device model is as follows: Among them, 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 respectively the current flowing through the surge protector after protection action and the maximum allowable current; S42, U res -I in Take N points on the curve and get the residual voltage U at the Nth point after piecewise linearization. res_N The expression of is as follows formula (5): U res_N =A N +B N I in_N (5); Among them, A N and B N is the coefficient of the Nth point expression after linearization.

2. The electrical system surge test modeling method according to claim 1, characterized in that: The step S1 is specifically as follows: S11. Decompose the transient process of induced lightning strikes, use an exponential function to describe the process of overvoltage generated by lightning on the common ground network of electrical system equipment and other buildings after lightning is connected to the lightning rod installed in the building, and ground the down conductor at the lightning strike location to the common ground network of the grounding system where the induction location of the induced lightning strike of the electrical system equipment is located. When lightning strikes at the lightning strike location, the impulse voltage generated at the induction location is as follows: Among them, R GND_i is the DC resistance of the grounding system from the lightning strike location to the sensing location, i represents the count in the formula, and I P1 is the shunt current of the maximum lightning current at the lightning strike location to the common ground network of the electrical system, τ1 is the time constant of the instantaneous current rise of the lightning strike, τ2 is the time constant of the current drop after the lightning strike, and k is the coefficient; S12, obtaining the peak value of the maximum lightning current through historical lightning meteorological data at the location of the electrical system; S13, obtaining the DC resistance R of the grounding system from the lightning strike position to the induction position by measurement or equivalent calculation GND_i ; S14, obtaining values ​​of τ1 and τ2 according to the lightning current level at the sensing position; S15. Establish interference source V in simulation tool P , so that its expression is as shown in formula (1), and based on formula (1), the lightning surge interference source model of the surge generator is established; S16, controlling the interference source V in the surge generator P The output resistance is set to make the output current between 0 and I P1 Adjust between.

3. The electrical system surge test modeling method according to claim 2, characterized in that: The step S14 is specifically as follows: There are two lightning current levels depending on whether the electrical system is installed inside or outside the building; The lightning current level outside the building is defined as level 1, and the time constants are τ1=5-10μs and τ2=100-350μs; The lightning current level in the building is defined as level 2, with time constants τ1 = 0.25-1.2 μs and τ2 = 50-100 μs.

4. The electrical system surge test modeling method according to claim 2, characterized in that: The step S2 is specifically as follows: S21. Identify all equipment in the electrical system that is sensitive to lightning strikes; S22, identifying the power ports and signal ports of all devices in the electrical system relative to a common ground network; S23. According to the identified connections between the power port and the signal port relative to different grounding points and the sensing position, all transfer paths are simulated to obtain a device port and impulse voltage conduction path model.

5. The electrical system surge test modeling method according to claim 4, characterized in that: The step S21 is specifically as follows: Identify the components in the electrical system connected to the building's power distribution network and containing power units and control units that are susceptible to overvoltage or overcurrent as sensitive equipment after lightning strikes the building's lightning rod; The step S22 is specifically as follows: According to the requirements of standard GB / T 17799.2 and the equipment specification, identify the power ports with DC power input / output function and AC power input / output function and the signal ports with signal transmission function.

6. The electrical system surge test modeling method according to claim 4, characterized in that: The step S3 is specifically as follows: S31. Establish equipment insulation coordination model based on insulation dielectric breakdown characteristics: Wherein, R is the insulation resistance of the insulating medium, ρ1 is the resistivity of the insulating medium under normal conditions, d is the material thickness of the insulating medium, k1 and k2 are coefficients of the resistivity under normal conditions related to the ambient temperature and humidity of the insulating medium, ρ2 is the resistivity of the insulating medium under breakdown conditions, E is the voltage field strength borne by the insulating medium, ε is the dielectric constant of the insulating medium, k3 and k4 are coefficients of the voltage field strength under breakdown conditions related to the ambient temperature and humidity of the insulating medium; S32. Obtain ε of the insulating medium from the material manual, measure k1, k2, k3 and k4 of the insulating medium by an experimental method, and substitute them into formula (2); S33, defining two failure modes of the insulating medium: leakage current failure and breakdown failure: When the insulation resistance of the insulating medium is ρ2d <R<R limit And E<εdk3k4 is the leakage current failure, then: Among them, U N_max is the maximum working voltage of the port where 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 electrical system surge test modeling method according to claim 6, characterized in that: After step S4, the following steps are also included: S5. Simulate the lightning protection process of the electrical system based on the lightning surge interference source model, the equipment port and impulse voltage conduction path model, the equipment insulation coordination model and the lightning protection device model.

8. The electrical system surge test modeling method according to claim 7, characterized in that: The step S5 is specifically as follows: S51. When the surge protector is not provided at the ports of all devices, 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, the process proceeds to step S52. Otherwise, the parameters of the insulating medium of the device port where the leakage current failure occurs are adjusted and the simulation is performed again until the leakage current failure does not occur at all device ports. 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-simulate and adjust the parameters of the surge protector until the breakdown failure does not occur on all device ports; S53, determining the parameters of the insulating medium in step S51 and the parameters of the surge protector in step S52, and implementing them accordingly in an actual electrical system.

9. The electrical system surge test modeling method according to claim 8, characterized in that: The surge protector parameter adjustment includes adjusting the specification of the surge protector, increasing the number of the surge protectors, or adjusting the position of the surge protectors.

10. An electrical system surge test modeling terminal, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps in the electrical system surge test modeling method described in any one of claims 1 to 9 are implemented.

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