On-off overvoltage suppression method for no-load transformer

Abstract

The invention discloses a no-load transformer on-off overvoltage suppression method, which comprises the steps of monitoring on-off operation of a no-load transformer in real time, determining a current cut-off angle, and controlling the on-off angle of a circuit breaker according to a current zero crossing point; a pre-charging capacitor is used for balancing the voltage at the switching-off moment, the voltage is released in a grading manner in the switching-off process, the inductive load is gradually cut off, and reverse current is applied in the switching-off operation to extinguish arc; transient current impact is triggered at the breaking moment so as to consume overvoltage energy, and the voltage difference value in reclosing operation is controlled. On the whole, the invention provides a multi-level overvoltage suppression solution, the reliability of the system is improved, and meanwhile, the dynamic control requirement of the power system can be effectively met.

Description

Technical Field

[0001] The invention relates to the technical field of overvoltage suppression, and in particular to a method for suppressing overvoltage when an unloaded transformer is switched off. Background Art

[0002] In the power system, the disconnection operation of the unloaded transformer will cause transient overvoltage, which is mainly caused by the arc generated when the circuit breaker contacts are separated, the inductive characteristics of the transformer, and the residual charge in the line. The existing technology usually uses lightning arresters or RC absorption devices to suppress the amplitude of overvoltage, but these devices can only partially reduce the peak value of overvoltage, and it is difficult to achieve precise control in the dynamic environment of complex power systems. With the expansion of the scale of the power grid and the complexity of the operating environment of the power system, traditional fixed suppression devices and methods have gradually shown their limitations. Therefore, the development of an innovative method that can monitor voltage and current changes in real time and combine dynamic control technology to suppress overvoltage has become a key requirement for solving the overvoltage problem during the disconnection process of unloaded transformers. Summary of the invention

[0003] In view of the above existing problems, the present invention is proposed.

[0004] Therefore, the present invention provides a method for suppressing overvoltage during the disconnection of an unloaded transformer, aiming to solve the problem of effective control of transient overvoltages during the disconnection operation of an unloaded transformer, specifically including how to monitor and adjust the dynamic changes of voltage and current in real time, thereby reducing the generation of overvoltage peaks during the disconnection process. On the basis of traditional suppression devices, the present invention proposes a series of methods based on dynamic current pulses, graded release voltage, pre-charge capacitor balance, and reverse current arc extinguishing, to control overvoltage at each stage of the disconnection moment, in order to cope with the suppression requirements under different current loads and voltage fluctuations. At the same time, the present invention also solves the optimal control of the difference between the power supply voltage and the residual voltage during the reclosing operation, ensuring that the reclosing operation is performed under appropriate voltage conditions to avoid the secondary generation of overvoltage.

[0005] In order to solve the above technical problems, the present invention provides the following technical solution, a method for suppressing overvoltage when an unloaded transformer is disconnected, comprising:

[0006] Monitor the disconnection operation of the no-load transformer in real time, determine the current cutoff angle, and control the circuit breaker's disconnection angle according to the current zero-crossing point;

[0007] Use pre-charged capacitors to balance the voltage at the moment of breaking, release the voltage in stages during the breaking process, gradually remove the inductive load, and apply reverse current to extinguish the arc during the opening operation;

[0008] A short current surge is triggered at the moment of breaking to consume overvoltage energy and control the voltage difference during the reclosing operation.

[0009] As a preferred solution of the method for suppressing overvoltage when disconnecting an unloaded transformer described in the present invention, the real-time monitoring of the disconnecting operation of the unloaded transformer includes real-time monitoring of the current waveform, obtaining the current cutoff angle, and issuing a disconnection instruction when the current approaches the zero point.

[0010] As a preferred solution of the method for suppressing overvoltage when no-load transformer is disconnected according to the present invention, the control of the disconnection angle of the circuit breaker includes collecting the current current phase and calculating the estimated time of the next zero crossing point based on the real-time monitoring of the current waveform;

[0011] The control system adjusts the opening and closing timing of the circuit breaker according to the current phase and zero-crossing prediction results, so that the time of issuing the action command matches the moment of the zero-crossing point; the phase control process is completed by synchronizing the current phase and the mechanical operation time of the circuit breaker. Taking into account the mechanical delay of the circuit breaker, the control system will send instructions in advance to make the actual separation time of the circuit breaker contacts consistent with the zero crossing point of the current, thereby achieving the matching of the opening operation and the zero crossing point of the current.

[0012] As a preferred solution of the method for suppressing overvoltage when disconnecting an unloaded transformer described in the present invention, the voltage at the moment of disconnection using a pre-charged capacitor to balance includes, before the disconnection operation, pre-charging the capacitor to the voltage amplitude on the transformer side through a preset charging device to achieve a state equal to the voltage on the transformer side. The charging device charges the capacitor with a constant voltage, and the pre-charge voltage of the capacitor is consistent with the voltage on the transformer side after reaching the set value. After the capacitor is pre-charged, the capacitor is connected in parallel to the disconnection circuit of the transformer through the control system, so that the capacitor voltage and the circuit voltage are balanced before disconnection.

[0013] As a preferred solution of the method for suppressing overvoltage when disconnecting an unloaded transformer of the present invention, the step-by-step voltage release includes, before disconnecting the unloaded transformer, grading the loads in the system according to the size of the inductance and presetting the removal order;

[0014] The control system gradually removes the load with the smallest inductance value, releases low voltage changes in the initial stage, and gradually removes the remaining load, disconnecting them in order from small to large inductance values. The control system monitors the current and voltage fluctuations each time the load is removed to ensure stable execution during the load removal process at each level, so that the reduction of inductive load matches the change in load inductance, thereby completing the process of releasing voltage step by step.

[0015] As a preferred solution of the method for suppressing overvoltage during breaking of an unloaded transformer of the present invention, the step of applying a reverse current to extinguish arc during the opening operation includes injecting a current with a phase opposite to that of the main current into the opening circuit through a dedicated reverse current generating device at the moment when the circuit breaker contacts are separated;

[0016] The phase of the reverse current is precisely adjusted by the phase control module to make it completely opposite to the phase of the main current, reaching a phase difference of 180 degrees. The magnitude and duration of the reverse current are determined based on the real-time monitoring data of the current before the tripping, and the current is injected;

[0017] The amplitude of the reverse current is dynamically adjusted by the control system according to the amplitude of the main current. The reverse current is introduced while the main current is reduced, weakening the arc formation conditions on the main current path when the contacts are separated.

[0018] As a preferred solution of the method for suppressing overvoltage when no-load transformer is disconnected described in the present invention, the transient current shock triggered at the moment of disconnection includes injecting a transient current shock pulse into the disconnection circuit through a high-frequency pulse current generating device at the moment when the circuit breaker disconnection operation is detected. The amplitude, frequency and duration of the pulse current are calculated by the control system to adjust the oscillation parameters of the inductance L and capacitance C in the circuit, so that the transient voltage and current fluctuations are controlled during the disconnection process, and the natural frequency and damping characteristics of the circuit are changed by the transient characteristics of the pulse current to suppress the transient overvoltage during the disconnection process.

[0019] As a preferred solution of the method for suppressing overvoltage when no-load transformer is disconnected described in the present invention, the control of the voltage difference in the reclosing operation includes that before the reclosing operation after the circuit breaker is disconnected, the system continuously collects the instantaneous values ​​of the line residual voltage and the power supply voltage, calculates the instantaneous voltage difference between the residual voltage and the power supply voltage through the data processing module, and analyzes its changing trend in real time, the control system presets a minimum voltage difference threshold, and generates a reclosing trigger signal at the moment when the voltage difference approaches the preset threshold based on the collected voltage waveform, and the system predicts the next minimum voltage difference moment of the voltage waveform in advance to synchronize the reclosing operation with this moment.

[0020] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of a method for suppressing overvoltage when disconnecting an unloaded transformer are implemented.

[0021] A computer-readable storage medium stores a computer program, wherein when the computer program is executed by a processor, the steps of a method for suppressing overvoltage when an unloaded transformer is disconnected are implemented.

[0022] Beneficial effects of the present invention: The present invention effectively suppresses the generation of transient overvoltage during disconnection through multi-step dynamic regulation during the disconnection process of the no-load transformer, and reduces the system's dependence on traditional fixed suppression devices. Based on innovative technologies such as real-time monitoring and precise control of current cutoff angles, graded load release, voltage balance, and short-term pulse regulation, the present invention can achieve adaptive control of overvoltage under various disconnection conditions. At the same time, by minimizing the difference between the power supply voltage and the residual voltage during the reclosing operation, the present invention ensures the safety and stability of the reclosing. Overall, the present invention provides a multi-level overvoltage suppression solution that can effectively meet the dynamic control requirements of the power system while improving system reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0024] Figure 1 A schematic flow chart of a method for suppressing overvoltage during disconnection of an unloaded transformer is provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0028] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0029] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Example 1, reference Figure 1 , which is the first embodiment of the present invention, provides a method for suppressing overvoltage when an unloaded transformer is disconnected, comprising:

[0032] S1: Monitor the breaking operation of the no-load transformer in real time, determine the current cutoff angle, and control the breaking angle of the circuit breaker according to the current zero-crossing point.

[0033] S2: Use pre-charged capacitors to balance the voltage at the moment of breaking, release the voltage in stages during the breaking process, gradually remove the inductive load, and apply reverse current to extinguish the arc during the opening operation.

[0034] S3: Trigger a short current surge at the moment of disconnection to consume overvoltage energy and control the voltage difference during the reclosing operation.

[0035] The real-time monitoring of the disconnection operation of the no-load transformer includes real-time monitoring of the current waveform, obtaining the current interruption angle, and issuing a disconnection instruction when the current is close to the zero crossing point.

[0036] The control of the breaking angle of the circuit breaker includes collecting the current current phase and calculating the estimated time of the next zero crossing based on the real-time monitoring of the current waveform;

[0037] The control system adjusts the opening and closing timing of the circuit breaker according to the current phase and zero-crossing prediction results, so that the time of issuing the action command matches the moment of the zero-crossing point; the phase control process is completed by synchronizing the current phase and the mechanical operation time of the circuit breaker. Taking into account the mechanical delay of the circuit breaker, the control system will send instructions in advance to make the actual separation time of the circuit breaker contacts consistent with the zero crossing point of the current, thereby achieving the matching of the opening operation and the zero crossing point of the current.

[0038] The use of pre-charged capacitors to balance the voltage at the moment of breaking includes, before the breaking operation, pre-charging the capacitor to the voltage amplitude on the transformer side through a preset charging device to achieve a state equal to the voltage on the transformer side. The charging device charges the capacitor with a constant voltage, and the pre-charge voltage of the capacitor is consistent with the voltage on the transformer side after reaching the set value. After the capacitor is pre-charged, the capacitor is connected in parallel to the breaking circuit of the transformer through the control system, so that the capacitor voltage and the circuit voltage are balanced before breaking.

[0039] The stepwise voltage release includes, before disconnecting the unloaded transformer, classifying the loads in the system according to the size of the inductance and presetting the disconnection order;

[0040] The control system gradually removes the load with the smallest inductance value, releases low voltage changes in the initial stage, and gradually removes the remaining load, disconnecting them in order from small to large inductance values. The control system monitors the current and voltage fluctuations each time the load is removed to ensure stable execution during the load removal process at each level, so that the reduction of inductive load matches the change in load inductance, thereby completing the process of releasing voltage step by step.

[0041] The said applying reverse current to extinguish arc in the opening operation includes, at the moment when the circuit breaker contacts are separated, injecting a current with a phase opposite to the main current into the opening circuit through a dedicated reverse current generating device;

[0042] The phase of the reverse current is precisely adjusted by the phase control module to make it completely opposite to the phase of the main current, reaching a phase difference of 180 degrees. The magnitude and duration of the reverse current are determined based on the real-time monitoring data of the current before the tripping, and the current is injected;

[0043] The amplitude of the reverse current is dynamically adjusted by the control system according to the amplitude of the main current. The reverse current is introduced while the main current is reduced, weakening the arc formation conditions on the main current path when the contacts are separated.

[0044] The transient current shock triggered at the moment of breaking includes: at the moment when the circuit breaker breaking operation is detected, a transient current shock pulse is injected into the breaking circuit through a high-frequency pulse current generating device, and the amplitude, frequency and duration of the pulse current are calculated by the control system to adjust the oscillation parameters of the inductance L and the capacitance C in the circuit, so that the transient voltage and current fluctuations are controlled during the breaking process, and the natural frequency and damping characteristics of the circuit are changed through the transient characteristics of the pulse current to suppress the transient overvoltage during the breaking process.

[0045] Improved natural frequency formula: Change the natural frequency f' of the circuit through transient impact:

[0046]

[0047] Where k is the impulse coefficient, which depends on the gain adjustment of the impulse current and the transient response of the loop impedance, I p The amplitude of the short-term current impulse pulse indicates the peak value of the pulse current in amperes (A). The equivalent damping coefficient ζ′ of the circuit is changed by the impulse pulse, so that the damping coefficient is no longer a constant:

[0048]

[0049] Among them, ζ is the damping coefficient when no shock is applied, α is the pulse shock adjustment coefficient, which reflects the impact of transient current pulse on system damping, t p is the duration of the pulse, indicating the duration of the short current impulse pulse, in seconds (s). p and t p Two impact parameters realize dynamic control of damping and improve overvoltage control effect.

[0050] The energy dissipation rate introduced by the pulse can be expressed as:

[0051]

[0052] Among them, V is the transient voltage before breaking, R is the equivalent resistance, P dissipation The transient energy dissipation power indicates the energy dissipation rate during the pulse application process, and the unit is watt (W). This dissipation model converts pulse energy into dissipated energy to reduce the voltage fluctuation during breaking.

[0053] The control of the voltage difference in the reclosing operation includes that before the reclosing operation after the circuit breaker is opened, the system continuously collects the instantaneous values ​​of the line residual voltage and the power supply voltage, calculates the instantaneous voltage difference between the residual voltage and the power supply voltage through the data processing module, and analyzes its changing trend in real time, the control system presets a minimum voltage difference threshold, and generates a reclosing trigger signal at the moment when the voltage difference approaches the preset threshold based on the collected voltage waveform, and the system predicts the next minimum voltage difference moment of the voltage waveform in advance to synchronize the reclosing operation with this moment.

[0054] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0055] Example 2

[0056] The second embodiment of the present invention is different from the previous embodiment in that:

[0057] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0058] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1A device that provides the functions specified in a block or multiple blocks.

[0059] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0060] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0061] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0062] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for suppressing overvoltage when no-load transformer is disconnected, characterized in that: include, Monitor the disconnection operation of the no-load transformer in real time, determine the current cutoff angle, and control the circuit breaker's disconnection angle according to the current zero-crossing point; Use pre-charged capacitors to balance the voltage at the moment of breaking, release the voltage in stages during the breaking process, gradually remove the inductive load, and apply reverse current to extinguish the arc during the opening operation; A short current surge is triggered at the moment of breaking to consume overvoltage energy and control the voltage difference during the reclosing operation.

2. A method for suppressing overvoltage when an unloaded transformer is disconnected as claimed in claim 1, characterized in that: The real-time monitoring of the disconnection operation of the no-load transformer includes real-time monitoring of the current waveform, obtaining the current interruption angle, and issuing a disconnection instruction when the current is close to the zero-crossing point.

3. A method for suppressing overvoltage when an unloaded transformer is disconnected as claimed in claim 2, characterized in that: The control of the breaking angle of the circuit breaker includes collecting the current current phase and calculating the estimated time of the next zero crossing based on the real-time monitoring of the current waveform; The control system adjusts the opening and closing timing of the circuit breaker according to the current phase and zero-crossing prediction results, so that the time of issuing the action command matches the moment of the zero-crossing point; the phase control process is completed by synchronizing the current phase and the mechanical operation time of the circuit breaker. Taking into account the mechanical delay of the circuit breaker, the control system will send instructions in advance to make the actual separation time of the circuit breaker contacts consistent with the zero crossing point of the current, thereby achieving the matching of the opening operation and the zero crossing point of the current.

4. A method for suppressing overvoltage when no-load transformer is disconnected as claimed in claim 3, characterized in that: The method of using a pre-charged capacitor to balance the voltage at the moment of breaking includes: before the breaking operation, pre-charging the capacitor to the voltage amplitude on the transformer side through a preset charging device to achieve a state equal to the voltage on the transformer side, and at the same time the charging device charges the capacitor with a constant voltage, and the pre-charge voltage of the capacitor is consistent with the voltage on the transformer side after reaching the set value. After the capacitor is pre-charged, the capacitor is connected in parallel to the breaking circuit of the transformer through the control system, so that the capacitor voltage and the circuit voltage are balanced before breaking.

5. A method for suppressing overvoltage when no-load transformer is disconnected as claimed in claim 4, characterized in that: The stepwise voltage release includes, before disconnecting the unloaded transformer, classifying the loads in the system according to the size of the inductance and presetting the disconnection order; The control system gradually removes the load with the smallest inductance value, releases low voltage changes in the initial stage, and gradually removes the remaining load, disconnecting them in order from small to large inductance values. The control system monitors the current and voltage fluctuations each time the load is removed to ensure stable execution during the load removal process at each level, so that the reduction of inductive load matches the change in load inductance, thereby completing the process of releasing voltage step by step.

6. A method for suppressing overvoltage when no-load transformer is disconnected as claimed in claim 5, characterized in that: The said applying reverse current to extinguish arc in the opening operation includes, at the moment when the circuit breaker contacts are separated, injecting a current with a phase opposite to the main current into the opening circuit through a dedicated reverse current generating device; The phase of the reverse current is precisely adjusted by the phase control module to make it completely opposite to the phase of the main current, reaching a phase difference of 180 degrees. The magnitude and duration of the reverse current are determined based on the real-time monitoring data of the current before the tripping, and the current is injected; The amplitude of the reverse current is dynamically adjusted by the control system according to the amplitude of the main current. The reverse current is introduced while the main current is reduced, weakening the arc formation conditions on the main current path when the contacts are separated.

7. A method for suppressing overvoltage when no-load transformer is disconnected as claimed in claim 6, characterized in that: The transient current shock triggered at the moment of breaking includes, at the moment of detecting the breaking operation of the circuit breaker, injecting a transient current shock pulse into the breaking circuit through a high-frequency pulse current generating device, the amplitude, frequency and duration of the pulse current are calculated by the control system to adjust the oscillation parameters of the inductance L and the capacitance C in the circuit, so that the transient voltage and current fluctuations are controlled during the breaking process, and the natural frequency and damping characteristics of the circuit are changed through the transient characteristics of the pulse current, so as to suppress the transient overvoltage during the breaking process.

8. A method for suppressing overvoltage when an unloaded transformer is disconnected as claimed in claim 7, characterized in that: The control of the voltage difference in the reclosing operation includes that before the reclosing operation after the circuit breaker is opened, the system continuously collects the instantaneous values ​​of the line residual voltage and the power supply voltage, calculates the instantaneous voltage difference between the residual voltage and the power supply voltage through the data processing module, and analyzes its changing trend in real time, the control system presets a minimum voltage difference threshold, and generates a reclosing trigger signal at the moment when the voltage difference approaches the preset threshold based on the collected voltage waveform, and the system predicts the next minimum voltage difference moment of the voltage waveform in advance to synchronize the reclosing operation with this moment.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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