A network configuration type converter control method and device for system transient stability improvement

Abstract

The application discloses a network-constructing type converter control method and device for improving system transient stability, and relates to the technical field of relay control. The method can shield a steady-state control strategy during a fault, and can input a transient additional control, so that the network-constructing type converter control for improving system transient stability is realized, the swing degree of a synchronous machine power angle after fault clearing is effectively reduced, and an unstable working condition (other control methods) can be restored to stability. The method responds to the power deviation of the network-constructing type converter through the transient additional control, generates a power loop angle increment through the control link, and does not depend on external signals (signal inputs of other devices), but only uses voltage and active power signals of a network-constructing type converter port.

Description

Technical Field

[0001] This invention discloses a grid-type converter control method and device for improving system transient stability, which relates to the field of relay control technology. Background Technology

[0002] There are currently two main types of transient stability control methods for grid-connected converters. Method 1 uses the original steady-state control strategy. Method 2 involves the control loop ceasing to respond to active power during the transient period (when the voltage is below a threshold) (masking active power deviation), and resuming steady-state control after the fault is cleared.

[0003] Existing methods only consider the transient stability of the grid-connected converter itself, without taking into account the transient stability of other synchronous machines in the system. For example, method 2 shields active power, which makes the grid-connected converter completely unresponsive to changes in the electrical quantities of the system, thus failing to improve the overall transient stability of the system. Summary of the Invention

[0004] This invention addresses the problems of existing technologies by providing a grid-type converter control method and apparatus for improving system transient stability. The technical solution adopted is as follows:

[0005] Firstly, a grid-type converter control method for improving system transient stability includes:

[0006] S1, Set the steady-state control exit voltage threshold. Based on the monitored grid-connected voltage of the grid-connected converter, exit steady-state control when the voltage drops below the steady-state control exit voltage threshold, and shield the power loop response.

[0007] S2, set the transient additional control start voltage threshold, and start the transient additional control when the voltage at the grid connection point of the grid-connected converter is lower than the transient additional control start voltage threshold;

[0008] S3 generates the input to the PI controller based on the amplitude of the unbalanced power, and outputs the functional loop potential through the limiting circuit.

[0009] S4, based on the monitored grid-connected voltage of the grid-connected converter, exit steady-state control when the transient additional control exit threshold is exceeded;

[0010] S5, based on the monitored grid-connected voltage of the grid-type converter, start steady-state control when the steady-state control start threshold is exceeded.

[0011] In some implementations, S2 includes:

[0012] S21, when the continuous time that the grid connection point voltage of the monitored grid-connected converter is less than the transient additional control start-up voltage threshold reaches a delay Tp, power fluctuation suppression is performed;

[0013] S22, the amplitude of the unbalanced power is not lower than the dead zone limit.

[0014] In some implementations, S3 includes:

[0015] S31, according to the grid-type converter, the unbalanced power... Respond and generate As the input of the PI controller,

[0016]

[0017] in, D p It is the transient additional damping coefficient;

[0018] S32, via When the grid-connected voltage of the grid-type converter U t The transient additional control start voltage threshold U L2 The power loop angle increment generated by transient additional control:

[0019]

[0020] in, K pp and K ip These are the parameters of the PI controller. T k It is an additional time constant;

[0021] S33, the power loop angle increment For the unbalanced power The response is:

[0022]

[0023] After the limiting stage, the output of the power loop is:

[0024]

[0025] In some implementations, in S5, the steady-state control exits at the voltage threshold. U L1 Transient additional control start voltage threshold U L2 Transient additional control exit threshold U L2out Steady-state control start-up threshold U L1out and steady-state voltage U The magnitude relationship of 0 is shown in the following formula:

[0026] U L2 < U L2out < U L1 < U L1out < U 0

[0027] In a second aspect, embodiments of the present invention provide a grid-type converter control device for improving system transient stability, comprising:

[0028] The response control module is used to set the steady-state control exit voltage threshold. Based on the monitored grid-connected voltage of the grid-connected converter, the steady-state control is exited when the voltage drops below the steady-state control exit voltage threshold, thus shielding the power loop response.

[0029] The control startup module is used to set the transient additional control startup voltage threshold, and to start the transient additional control when the voltage at the grid connection point of the grid-connected converter is lower than the transient additional control startup voltage threshold.

[0030] The potential output module is used to generate the input of the PI controller based on the amplitude of the unbalanced power, and output the functional loop potential through the limiting circuit.

[0031] The transient control module is used to exit steady-state control when the monitored grid-connected voltage of the grid-connected converter exceeds the transient additional control exit threshold.

[0032] The steady-state control module is used to initiate steady-state control when the monitored grid-connected voltage of the grid-connected converter exceeds the steady-state control start-up threshold.

[0033] In some implementations, the control startup module includes:

[0034] The first adjustment unit is used to monitor the grid connection point voltage of the grid-connected converter and suppress power fluctuations when the continuous time when the voltage is less than the transient additional control start-up voltage threshold reaches a delay Tp.

[0035] The second adjustment unit is used to ensure that the amplitude of the unbalanced power is not lower than the dead zone limit.

[0036] In some implementations, the potential output module includes:

[0037] The controller input unit is used to adjust the unbalanced power according to the grid-type converter. Respond and generate As input to the PI controller:

[0038]

[0039] in, D p It is the transient additional damping coefficient;

[0040] Loop processing unit, used for passing When the grid-connected voltage of the grid-type converter U t The transient additional control start voltage threshold U L2 The power loop angle increment generated by transient additional control:

[0041]

[0042] in, K pp and K ip These are the parameters of the PI controller. T k It is an additional time constant;

[0043] Power output unit, used for the power loop angle increment For the unbalanced power The response is:

[0044]

[0045] After the limiting stage, the output of the power loop is:

[0046]

[0047] In some implementations, the steady-state control module has a steady-state control exit voltage threshold. U L1 Transient additional control start voltage threshold U L2 Transient additional control exit threshold U L2out Steady-state control start-up threshold U L1out and steady-state voltage U The magnitude relationship of 0 is shown in the following formula:

[0048] U L2 < U L2out < U L1 < U L1out < U 0

[0049] Thirdly, embodiments of the present invention provide an electronic device, including a memory and a processor, wherein the memory is used to store one or more computer instructions, wherein when the one or more computer instructions are executed by the processor, they implement the method described in the first aspect above.

[0050] Fourthly, embodiments of the present invention provide a computer storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, it implements the method described in the first aspect.

[0051] One or more embodiments of the present invention can bring at least the following beneficial effects:

[0052] The method of this invention shields the steady-state control strategy during a fault and engages transient additional control, which can improve the transient stability of the grid-type converter control, effectively reduce the degree of synchronous motor power angle swing after fault clearance, and can restore stability from unstable conditions (other control methods). The method of this invention responds to the power deviation of the grid-type converter itself through transient additional control, and generates the power loop angle increment through the control loop; it does not rely on external signals (signal input from other devices), but only uses the voltage and active power signals of the grid-type converter port. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a schematic diagram of the switching process of steady-state control of a grid-type converter in a typical system provided in the embodiments of the present invention;

[0055] Figure 2 This is a schematic diagram of the steady-state control of a grid-type converter, i.e., its switching process, provided by an embodiment of the present invention for improving the transient stability of a system.

[0056] Figure 3 This is a schematic diagram of transient additional control switching provided in an embodiment of the present invention;

[0057] Figure 4 This is a schematic diagram of the switcher switching process after a fault occurs, provided in an embodiment of the present invention;

[0058] Figure 5 This is a schematic diagram of the switcher switching process after fault clearance provided in an embodiment of the present invention;

[0059] Figure 6 This is a schematic diagram of the control effect of the first working condition provided in the embodiment of the present invention; wherein (a) is a schematic diagram of synchronization and power angle, and (b) is a schematic diagram of the active power of the synchronizing machine;

[0060] Figure 7 This is a schematic diagram of the control effect of the second working condition provided in the embodiment of the present invention; wherein (a) is a schematic diagram of synchronization and power angle, and (b) is a schematic diagram of the active power of the synchronizing machine;

[0061] Figure 8 This is a schematic diagram of the control effect of the third working condition provided in the embodiment of the present invention; wherein (a) is a schematic diagram of synchronization and power angle, and (b) is a schematic diagram of the active power of the synchronizing machine. Detailed Implementation

[0062] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0063] Example 1:

[0064] Firstly, a grid-type converter control method for improving system transient stability includes:

[0065] S1, Set the steady-state control exit voltage threshold. Based on the monitored grid-connected voltage of the grid-connected converter, exit steady-state control when the voltage drops below the steady-state control exit voltage threshold, and shield the power loop response.

[0066] S2, set the transient additional control start voltage threshold, and start the transient additional control when the voltage at the grid connection point of the grid-connected converter is lower than the transient additional control start voltage threshold;

[0067] S3 generates the input to the PI controller based on the amplitude of the unbalanced power, and outputs the functional loop potential through the limiting circuit.

[0068] S4, based on the monitored grid-connected voltage of the grid-connected converter, exit steady-state control when the transient additional control exit threshold is exceeded;

[0069] S5, based on the monitored grid-connected voltage of the grid-type converter, start steady-state control when the steady-state control start threshold is exceeded.

[0070] Typical systems containing new energy sources, synchronous machines, and grid-type converters include: Figure 1 As shown, it includes grid-type converters, new energy sources, synchronous machines, and equivalent systems.

[0071] According to S1, set the steady-state control exit voltage threshold. U L1 Monitoring the voltage at the grid connection point of the grid-connected converter U t .when U t < U L1 Switch 1 switches from state 1 to state 2. The original control strategy is locked out, meaning the grid-connected converter no longer responds to unbalanced power. The steady-state control of the grid-connected converter, i.e., its switching process, is as follows... Figure 2 As shown.

[0072] Figure 2 middle, P ref This is a reference value for the active power of a grid-type converter. P e The output active power value of the grid-type converter. D v The damping coefficient is... T J The inertia coefficient, ω 0 is the system's reference angular frequency, Δ P This represents unbalanced power. At this point, the virtual internal potential angle of the grid-connected converter is... θ vsg Maintain a constant.

[0073]

[0074] in, θ vsg0 The output angle for steady-state control. θ 0 is the initial angle obtained from the power flow.

[0075] Next, according to S2, set the transient additional control start-up voltage threshold. U L2 Monitoring the voltage at the grid connection point of the grid-connected converter U t .when U t < U L2 Switcher 2 switches from state 1 to state 2, and transient additional control is activated.

[0076] The transient additional control structure of a grid-type converter, i.e., its switching process, is as follows: Figure 3 As shown.

[0077] After the fault occurs, the overall switching logic of switcher 1 and switcher 2 is as follows: Figure 4 As shown.

[0078] When the transient additional control is activated, the state 2 input value of switch 2 is still 0. The following two conditions must be met for the state 2 input value of switch 2 to be Δ. P :

[0079] S21, when the continuous time for which the grid-connected voltage of the monitored grid-connected converter is less than the transient additional control start-up voltage threshold reaches a delay Tp, power fluctuation suppression is performed:

[0080] U t < U L2 The continuous time needs to reach Tp. The delay Tp is used to suppress power fluctuations.

[0081] S22, the amplitude of the unbalanced power is not lower than the dead zone limit: |Δ P |< P in , that is, Δ P The amplitude needs to exceed the dead zone limit.

[0082] Next, according to S3, the transient additional control actions during the fault include:

[0083] S31, according to the grid-type converter, the unbalanced power... Respond and generate As the input of the PI controller,

[0084]

[0085] in, D p It is the transient additional damping coefficient;

[0086] S32, via When the grid-connected voltage of the grid-type converter U t The transient additional control start voltage threshold U L2 The power loop angle increment generated by transient additional control:

[0087]

[0088] in, K pp and K ip These are the parameters of the PI controller. Tk It is an additional time constant;

[0089] S33, the power loop angle increment For the unbalanced power The response is:

[0090]

[0091] After the limiting stage, the output of the power loop is:

[0092]

[0093] Next, according to S4, the transient additional control is deactivated. This occurs when the voltage at the grid connection point of the grid-connected converter exceeds the transient additional control deactivation threshold. U L2out ,Right now U t > U L2out Switcher 2 switches from state 2 to state 1. Transient additional control is exited.

[0094] Next, according to S5, steady-state control is initiated. When the grid-connected voltage of the grid-connected converter exceeds the steady-state control initiation threshold... U L1out ,Right now U t > U L1out Switcher 1 switches from state 2 to state 1. Steady-state control is initiated.

[0095] After the fault is cleared, the overall switching logic of switcher 1 and switcher 2 is as follows: Figure 5 As shown.

[0096] In S5, the steady-state control exits the voltage threshold. U L1 Transient additional control start voltage threshold U L2 Transient additional control exit threshold U L2out Steady-state control start-up threshold U L1out and steady-state voltage U The magnitude relationship of 0 is shown in the following formula:

[0097] U L2 < U L2out < U L1 < U L1out < U 0

[0098] against Figure 1 The system shown has three operating conditions. Control method 1 uses steady-state control, while control method 2 uses a shielded active power control strategy.

[0099] Operating Condition 1:

[0100] The new energy output power is 100MW, the grid-type converter's active power output is 100MW, and the synchronous machine's active power output is 200MW. A three-phase short-circuit fault occurred on the 500kV line in the system, with a fault duration of 0.2 s. The power angle and active power of the grid-type converter and synchronous machine are as follows: Figure 6 As shown, by employing the control method proposed in this invention, the maximum swing angle of the synchronizer is smaller than that of other control methods.

[0101] Operating Condition 2:

[0102] The grid-connected new energy output power is 200MW, the grid-connected converter output power is 100MW, and the synchronous machine output power is 200MW. A three-phase short-circuit fault occurred on the 500kV transmission line, with a transition resistance of 0.04pu and a fault duration of 0.2s. The control method proposed in this invention, along with three other control methods involving modifying reference values, are described below. The synchronous machine power angle and active power are as follows: Figure 7 As shown.

[0103] Operating Condition 3:

[0104] The grid-connected new energy output power is 200MW, the GFM output power is 100MW, and the synchronous machine output power is 250MW. A three-phase metallic short-circuit fault occurred on the 500kV transmission line, with a fault duration of 0.3s. This invention proposes three control strategies and methods, including modifying reference values, for the synchronous machine power angle and active power, as shown in the following examples. Figure 8 As shown.

[0105] Example 2:

[0106] In a second aspect, embodiments of the present invention provide a grid-type converter control device for improving system transient stability, comprising:

[0107] The response control module is used to set the steady-state control exit voltage threshold. Based on the monitored grid-connected voltage of the grid-connected converter, the steady-state control is exited when the voltage drops below the steady-state control exit voltage threshold, thus shielding the power loop response.

[0108] The control startup module is used to set the transient additional control startup voltage threshold, and to start the transient additional control when the voltage at the grid connection point of the grid-connected converter is lower than the transient additional control startup voltage threshold.

[0109] The potential output module is used to generate the input of the PI controller based on the amplitude of the unbalanced power, and output the functional loop potential through the limiting circuit.

[0110] The transient control module is used to exit steady-state control when the monitored grid-connected voltage of the grid-connected converter exceeds the transient additional control exit threshold.

[0111] The steady-state control module is used to initiate steady-state control when the monitored grid-connected voltage of the grid-connected converter exceeds the steady-state control start-up threshold.

[0112] Furthermore, the control startup module includes:

[0113] The first adjustment unit is used to monitor the grid connection point voltage of the grid-connected converter and suppress power fluctuations when the continuous time when the voltage is less than the transient additional control start-up voltage threshold reaches a delay Tp.

[0114] The second adjustment unit is used to ensure that the amplitude of the unbalanced power is not lower than the dead zone limit.

[0115] Furthermore, the potential output module includes:

[0116] The controller input unit is used to adjust the unbalanced power according to the grid-type converter. Respond and generate As input to the PI controller:

[0117]

[0118] in, D p It is the transient additional damping coefficient;

[0119] Loop processing unit, used for passing When the grid-connected voltage of the grid-type converter U t The transient additional control start voltage threshold U L2 The power loop angle increment generated by transient additional control:

[0120]

[0121] in, K pp and K ip These are the parameters of the PI controller. T k It is an additional time constant;

[0122] Power output unit, used for the power loop angle increment For the unbalanced power The response is:

[0123]

[0124] After the limiting stage, the output of the power loop is:

[0125]

[0126] Furthermore, in the steady-state control module, the steady-state control exit voltage threshold... U L1 Transient additional control start voltage threshold U L2 Transient additional control exit threshold U L2out Steady-state control start-up threshold U L1out and steady-state voltage U The magnitude relationship of 0 is shown in the following formula:

[0127] U L2 < U L2out < U L1 < U L1out < U 0

[0128] Example 3:

[0129] This embodiment also provides an electronic device, including a memory and a processor, wherein the memory is used to store one or more computer instructions, wherein the one or more computer instructions are executed by the processor to implement the method of Embodiment 1;

[0130] In practical applications, the processor can be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller unit (MCU), microprocessor, or other electronic components to execute the methods described in the above embodiments.

[0131] The method implemented in this embodiment is as shown in Embodiment 1.

[0132] Example 4:

[0133] This embodiment also provides a computer storage medium, in which a computer program is stored, and when the computer program is executed by one or more processors, it implements the method of embodiment one.

[0134] The computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0135] The method implemented in this embodiment is as shown in Embodiment 1.

[0136] In the several embodiments provided in this invention, it should be understood that the disclosed systems and methods can also be implemented in other ways. The system and method embodiments described above are merely illustrative.

[0137] It should be noted that, in this document, the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0138] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A grid-type converter control method for improving system transient stability, characterized in that, include: S1, Set a steady-state control exit voltage threshold. Based on the monitored grid-connected voltage of the grid-connected converter, when the voltage drops below the steady-state control exit voltage threshold, control the first switch to switch from the on state to the off state to exit steady-state control and shield the power loop response. The first switch is used to control the on and off states of the power loop response loop corresponding to the steady-state control. S2, set the transient additional control start voltage threshold, and according to the grid connection point voltage of the grid-connected converter, when it is lower than the transient additional control start voltage threshold, control the second switch to switch from the off state to the on state to start the transient additional control; wherein, the second switch is used to control the on and off of the control loop corresponding to the transient additional control; S3 generates the input to the PI controller based on the amplitude of the unbalanced power, and outputs the functional loop potential through the limiting circuit. S4, based on the monitored grid-connected voltage of the grid-connected converter, when the transient additional control exit threshold is exceeded, control the second switch to switch back from the on state to the off state to exit the transient additional control; S5, based on the monitored grid-connected voltage of the grid-connected converter, when the steady-state control start threshold is exceeded, control the first switch to switch back from the disconnected state to the on state to start steady-state control; In S5, the steady-state control exit voltage threshold U L1 Transient additional control start voltage threshold U L2 Transient additional control exit threshold U L2out Steady-state control start-up threshold U L1out and steady-state voltage U The magnitude relationship of 0 is shown in the following formula: U L2 < U L2out < U L1 < U L1out < U 0。 2. The method according to claim 1, characterized in that, S2 includes: S21, when the continuous time that the grid connection point voltage of the monitored grid-connected converter is less than the transient additional control start-up voltage threshold reaches a delay Tp, power fluctuation suppression is performed; S22, the amplitude of the unbalanced power is not lower than the dead zone limit.

3. The method according to claim 2, characterized in that, S3 include: S31, according to the grid-type converter, the unbalanced power... Respond and generate As the input of the PI controller, in, D p It is the transient additional damping coefficient; S32, via When the grid-connected voltage of the grid-type converter U t The transient additional control start voltage threshold U L2 The power loop angle increment generated by transient additional control: in, K pp and K ip These are the parameters of the PI controller. T k It is an additional time constant; S33, the power loop angle increment For the unbalanced power The response is: After the limiting stage, the output of the power loop is: in, It is the output angle of steady-state control. The initial angle is obtained from the power flow.

4. A grid-type converter control device for improving system transient stability, characterized in that, include: The response control module is used to set the steady-state control exit voltage threshold. Based on the monitored grid-connected voltage of the grid-connected converter, when the voltage is lower than the steady-state control exit voltage threshold, the module controls the first switch to switch from the on state to the off state to exit steady-state control and shield the power loop response. The first switch is used to control the on and off states of the power loop response loop corresponding to the steady-state control. The control startup module is used to set the transient additional control startup voltage threshold. Based on the grid connection point voltage of the grid-connected converter, when the voltage is lower than the transient additional control startup voltage threshold, the module controls the second switch to switch from the off state to the on state to start the transient additional control. The second switch is used to control the on and off states of the control loop corresponding to the transient additional control. The potential output module is used to generate the input of the PI controller based on the amplitude of the unbalanced power, and output the functional loop potential through the limiting circuit. The transient control module is used to control the second switch to switch back from the on state to the off state when the monitored grid-connected voltage of the grid-connected converter exceeds the transient additional control exit threshold, so as to exit the transient additional control. The steady-state control module is used to control the first switch to switch back from the off state to the on state when the monitored grid-connected voltage of the grid-connected converter exceeds the steady-state control start threshold, so as to start the steady-state control. In the steady-state control module, the steady-state control exit voltage threshold is... U L1 Transient additional control start voltage threshold U L2 Transient additional control exit threshold U L2out Steady-state control start-up threshold U L1out and steady-state voltage U The magnitude relationship of 0 is shown in the following formula: U L2 < U L2out < U L1 < U L1out < U 0。 5. The apparatus according to claim 4, characterized in that, The control startup module includes: The first adjustment unit is used to monitor the grid connection point voltage of the grid-connected converter and suppress power fluctuations when the continuous time when the voltage is less than the transient additional control start-up voltage threshold reaches a delay Tp. The second adjustment unit is used to ensure that the amplitude of the unbalanced power is not lower than the dead zone limit.

6. The apparatus according to claim 5, characterized in that, The potential output module includes: The controller input unit is used to adjust the unbalanced power according to the grid-type converter. Respond and generate As input to the PI controller: in, D p It is the transient additional damping coefficient; Loop processing unit, used for passing When the grid-connected voltage of the grid-type converter U t The transient additional control start voltage threshold U L2 The power loop angle increment generated by transient additional control: in, K pp and K ip These are the parameters of the PI controller. T k It is an additional time constant; Power output unit, used for the power loop angle increment For the unbalanced power The response is: After the limiting stage, the output of the power loop is: in, It is the output angle of steady-state control. The initial angle is obtained from the power flow.

7. An electronic device, characterized in that, The system includes a memory and a processor, the memory being used to store one or more computer instructions, wherein the one or more computer instructions, when executed by the processor, implement the method as described in any one of claims 1-3.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains a computer program that, when executed by a processor, is used to implement the method as described in any one of claims 1-3.

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