DC system control method and device, terminal and storage medium

Abstract

The present disclosure relates to the field of power electronic power conversion technology, and in particular to a DC system control method and device, terminal, and storage medium. The DC system control method comprises: obtaining a DC power command value corresponding to the DC system; determining a DC current command value and a DC voltage command value corresponding to the DC system based on the DC power command value, wherein the DC current command value is not less than the minimum DC current limit; controlling the current control end modular multilevel converter MMC in the DC system based on the DC current command value, and controlling the voltage control end MMC in the DC system based on the DC voltage command value, wherein the current control end MMC and / or the voltage control end MMC is a UCH-MMC based on a unidirectional current-type H-bridge submodule. The present disclosure using the above-mentioned scheme can improve the flexibility of DC system control.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power electronic power conversion, and in particular to a direct current system control method and device, a terminal, and a storage medium. Background Art

[0002] Modular multilevel converters (MMCs) feature a modular design and are widely used in DC systems due to their large number of levels, good harmonic characteristics, and low losses. However, the distributed capacitance design of MMCs leads to significant energy fluctuations within the converter arms during operation, necessitating large submodule capacitance values ​​to effectively suppress the voltage fluctuations caused by these energy fluctuations. The large capacitance used in MMCs results in bulky design and low power density, which in turn increases manufacturing costs.

[0003] The MMC based on the unidirectional current H-bridge submodule (UCH-SM) (UCH-SM-based MMC, UCH-MMC) can effectively reduce the energy fluctuation in the converter bridge arm by increasing the AC voltage, thereby reducing the capacitance requirement. However,

[0004] However, the UCH-MMC structure requires that the current flowing through the converter bridge arm be unidirectional, meaning its direction does not change. Because the bridge arm current primarily consists of a DC component and a fundamental frequency AC component, and the DC and fundamental frequency AC components depend on the DC and AC currents at the MMC ports, respectively, the UCH-MMC requires DC current to flow. This means that when DC power is being transmitted (i.e., when active power is flowing on the AC side), DC current is inevitably present.

[0005] In related technologies, AC systems connected to DC systems require the UCH-MMC to maintain a certain level of reactive power exchange capability even when the DC power is zero. This allows it to support the grid's AC voltage or limit its amplitude, or to provide or absorb reactive power. Under traditional operation, the UCH-MMC's DC voltage is typically maintained at its rated value, and the DC current is proportional to the DC power. Therefore, when the DC power is very low, the DC current is also low, limiting the AC reactive power output capability.

[0006] Therefore, how to make the DC system maintain a certain DC current when the DC power is very low, so as to ensure that the UCH-MMC has a certain reactive power exchange capability and thus improve the flexibility of DC system control, has become the focus of people's attention. Summary of the Invention

[0007] The present disclosure provides a new energy power generation and transmission system based on high-voltage direct current series tapping and a control method, the main purpose of which is to improve the convenience of direct current system control. The technical solutions of the present disclosure are as follows:

[0008] According to a first aspect of an embodiment of the present disclosure, a DC system control method is provided, comprising:

[0009] Obtain the DC power command value corresponding to the DC system;

[0010] Determining a DC current command value and a DC voltage command value corresponding to the DC system according to the DC power command value, wherein the DC current command value is not less than a minimum DC current limit value;

[0011] The current control end modular multilevel converter MMC in the DC system is controlled according to the DC current command value, and the voltage control end MMC in the DC system is controlled according to the DC voltage command value, wherein the current control end MMC and / or the voltage control end MMC is a UCH-MMC based on a unidirectional current-type H-bridge submodule.

[0012] Optionally, in one embodiment of the present disclosure, controlling the current control-end modular multilevel converter MMC in the DC system according to the DC current command value includes:

[0013] According to the DC current command value, a DC current inner loop controller is used to perform DC current closed-loop control on the current control terminal MMC to obtain a DC component of the first bridge arm voltage reference value;

[0014] Obtaining a d-axis current command value and a q-axis current command value, and performing AC current closed-loop control on the current control terminal MMC using an AC current inner-loop controller to obtain an AC component of the first bridge arm voltage reference value;

[0015] The first bridge arm voltage reference value is determined according to the DC component of the first bridge arm voltage reference value and the AC component of the first bridge arm voltage reference value, so as to control the bridge arm output voltage of the current control terminal MMC.

[0016] Optionally, in one embodiment of the present disclosure, controlling the voltage control terminal MMC in the DC system according to the DC voltage command value includes:

[0017] According to the DC voltage command value, a DC voltage outer loop controller is used to perform DC voltage closed-loop control on the voltage control terminal MMC to obtain a DC voltage and current command value;

[0018] According to the DC voltage and current command value, a DC current inner loop controller is used to perform DC current closed-loop control on the voltage control terminal MMC to obtain a DC component of the second bridge arm voltage reference value;

[0019] Obtaining a d-axis current command value and a q-axis current command value, and performing AC current closed-loop control on the voltage control terminal MMC using an AC current inner-loop controller to obtain an AC component of the second bridge arm voltage reference value;

[0020] The second bridge arm voltage reference value is determined according to the DC component of the second bridge arm voltage reference value and the AC component of the second bridge arm voltage reference value, so as to control the bridge arm output voltage of the voltage control terminal MMC.

[0021] Optionally, in one embodiment of the present disclosure, obtaining the d-axis current command value and the q-axis current command value includes:

[0022] Performing closed-loop control of the capacitor voltage on the DC system using a capacitor voltage outer-loop controller to obtain a d-axis current command value;

[0023] The reactive power outer loop controller is used to perform reactive power closed loop control on the DC system to obtain a q-axis current command value.

[0024] Optionally, in one embodiment of the present disclosure, the DC current inner loop controller and the AC current inner loop controller are proportional-integral (PI) controllers.

[0025] Optionally, in one embodiment of the present disclosure, the current control terminal MMC is a UCH-MMC, and the voltage control terminal MMC is a DC voltage variable MMC;

[0026] or,

[0027] The current control end MMC is the DC voltage variable MMC, and the voltage control end MMC is the UCH-MMC.

[0028] Optionally, in one embodiment of the present disclosure, the DC voltage variable MMC is any one of a UCH-MMC, a full-bridge MMC, and a full-half-bridge hybrid MMC.

[0029] According to a second aspect of an embodiment of the present disclosure, there is provided a DC system control device, comprising:

[0030] The command value acquisition module is used to obtain the DC power command value corresponding to the DC system;

[0031] an instruction value determination module, configured to determine a DC current instruction value and a DC voltage instruction value corresponding to the DC system according to the DC power instruction value, wherein the DC current instruction value is not less than a minimum DC current limit value;

[0032] An MMC control module is configured to control a current control-end modular multilevel converter MMC in the DC system according to the DC current command value, and to control a voltage control end MMC in the DC system according to the DC voltage command value, wherein the current control end MMC and / or the voltage control end MMC is a UCH-MMC based on a unidirectional current-type H-bridge submodule.

[0033] Optionally, in one embodiment of the present disclosure, the command value determination module includes a DC control submodule, an AC control submodule, and a reference value determination submodule. The command value determination module is configured to control a current control-end modular multilevel converter MMC in the DC system according to the DC current command value:

[0034] The DC control submodule is configured to perform DC current closed-loop control on the current control terminal MMC using a DC current inner-loop controller according to the DC current command value, so as to obtain a DC component of the first bridge arm voltage reference value;

[0035] The AC control submodule is used to obtain a d-axis current command value and a q-axis current command value, and perform AC current closed-loop control on the current control terminal MMC using an AC current inner-loop controller to obtain an AC component of the first bridge arm voltage reference value;

[0036] The reference value determination submodule is used to determine the first bridge arm voltage reference value according to the DC component of the first bridge arm voltage reference value and the AC component of the first bridge arm voltage reference value, so as to control the bridge arm output voltage of the current control terminal MMC.

[0037] Optionally, in one embodiment of the present disclosure, the command value determination module includes a voltage control submodule, a DC control submodule, an AC control submodule, and a reference value determination submodule. The command value determination module is configured to control the voltage control terminal MMC in the DC system according to the DC voltage command value:

[0038] The voltage control submodule is configured to perform DC voltage closed-loop control on the voltage control terminal MMC using a DC voltage outer-loop controller according to the DC voltage command value to obtain a DC voltage and current command value;

[0039] The DC control submodule is configured to perform DC current closed-loop control on the voltage control terminal MMC using a DC current inner-loop controller according to the DC voltage and current command value, so as to obtain a DC component of the second bridge arm voltage reference value;

[0040] The AC control submodule is used to obtain a d-axis current command value and a q-axis current command value, and perform AC current closed-loop control on the voltage control terminal MMC using an AC current inner-loop controller to obtain an AC component of the second bridge arm voltage reference value;

[0041] The reference value determination submodule is used to determine the second bridge arm voltage reference value according to the DC component of the second bridge arm voltage reference value and the AC component of the second bridge arm voltage reference value, so as to control the bridge arm output voltage of the voltage control terminal MMC.

[0042] Optionally, in one embodiment of the present disclosure, the AC control submodule, when used to obtain the d-axis current command value and the q-axis current command value, is specifically used to:

[0043] Performing closed-loop control of the capacitor voltage on the DC system using a capacitor voltage outer-loop controller to obtain a d-axis current command value;

[0044] The reactive power outer loop controller is used to perform reactive power closed loop control on the DC system to obtain a q-axis current command value.

[0045] Optionally, in one embodiment of the present disclosure, the DC current inner loop controller and the AC current inner loop controller are proportional-integral (PI) controllers.

[0046] Optionally, in one embodiment of the present disclosure, the current control terminal MMC is a UCH-MMC, and the voltage control terminal MMC is a DC voltage variable MMC;

[0047] or,

[0048] The current control end MMC is the DC voltage variable MMC, and the voltage control end MMC is the UCH-MMC.

[0049] Optionally, in one embodiment of the present disclosure, the DC voltage variable MMC is any one of a UCH-MMC, a full-bridge MMC, and a full-half-bridge hybrid MMC.

[0050] According to a third aspect of an embodiment of the present disclosure, a terminal is provided, including:

[0051] at least one processor; and

[0052] a memory communicatively connected to the at least one processor; wherein,

[0053] The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform any one of the methods described in the above aspect.

[0054] According to a fourth aspect of an embodiment of the present disclosure, a non-transitory computer-readable storage medium storing computer instructions is provided, wherein the computer instructions are used to enable the computer to execute any one of the methods described in the aforementioned aspect.

[0055] According to a fifth aspect of an embodiment of the present disclosure, a computer program product is provided, comprising a computer program, wherein the computer program implements the method described in any one of the aforementioned aspects when executed by a processor.

[0056] In summary, in one or more embodiments of the present disclosure, a DC power command value corresponding to a DC system is obtained; a DC current command value and a DC voltage command value corresponding to the DC system are determined based on the DC power command value, wherein the DC current command value is not less than a minimum DC current limit; a current control terminal modular multilevel converter (MMC) in the DC system is controlled based on the DC current command value, and a voltage control terminal (MMC) in the DC system is controlled based on the DC voltage command value, wherein the current control terminal (MMC) and / or the voltage control terminal (MMC) are UCH-MMCs based on unidirectional current-type H-bridge submodules. Therefore, by calculating a DC current command value and a DC voltage command value based on the DC power command value, and controlling the current control terminal (MMC) based on the DC current command value, and controlling the voltage control terminal (MMC) based on the DC voltage command value, the DC system can maintain a certain DC current when the DC power is very low, thereby ensuring a certain reactive power exchange capability when the current control terminal (MMC) and / or the voltage control terminal (MMC) are UCH-MMCs, thereby improving the flexibility of DC system control. In addition, by setting a minimum DC current limit, it can be ensured that the DC current will not be lower than the minimum DC current limit when the DC system is operating normally, thereby reducing the operating losses of the DC system and the MMC while ensuring that the MMC has reactive power exchange capability.

[0057] Additional aspects and advantages of the present disclosure will be given in part in the description below and in part will be obvious from the description below, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The above and / or additional aspects and advantages of the present disclosure will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0059] Figure 1A schematic flow chart showing a DC system control method provided by an embodiment of the present disclosure is shown;

[0060] Figure 2 A schematic structural diagram of a DC system provided by an embodiment of the present disclosure is shown;

[0061] Figure 3 A schematic structural diagram of a UCH-MMC provided in an embodiment of the present disclosure is shown;

[0062] Figure 4 A schematic diagram of the structure of a UCH-SM provided by an embodiment of the present disclosure is shown;

[0063] Figure 5 A controller block diagram of a current control terminal MMC provided by an embodiment of the present disclosure is shown;

[0064] Figure 6 A controller block diagram of a voltage control terminal MMC provided by an embodiment of the present disclosure is shown;

[0065] Figure 7 A schematic structural diagram of a first DC system control device provided by an embodiment of the present disclosure is shown;

[0066] Figure 8 A schematic structural diagram of a second DC system control device provided by an embodiment of the present disclosure is shown;

[0067] Figure 9 A schematic structural diagram of a third DC system control device provided by an embodiment of the present disclosure is shown;

[0068] Figure 10 It is a block diagram of a terminal used to implement the DC system control method according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0069] The following describes in detail embodiments of the present disclosure, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present disclosure and are not to be construed as limiting the present disclosure. On the contrary, the embodiments of the present disclosure include all variations, modifications, and equivalents that fall within the spirit and scope of the appended claims.

[0070] The present disclosure is described in detail below with reference to specific embodiments.

[0071] like Figure 1 As shown, Figure 1This figure shows a flow chart of a DC system control method provided by an embodiment of the present disclosure. The method can be implemented using a computer program and can be run on a device that performs DC system control. The computer program can be integrated into an application or run as a standalone tool application.

[0072] The DC system control device may be a terminal having a DC system control function, including but not limited to a wearable device, a handheld device, a personal computer, a tablet computer, an in-vehicle device, a smart phone, a computing device, or other processing device connected to a wireless modem. In different networks, the terminal may be called by different names, such as user equipment, access terminal, subscriber unit, subscriber station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device, cellular phone, cordless phone, personal digital assistant (PDA), terminal in a 5th Generation Mobile Communication Technology (5G) network, a 4th Generation Mobile Communication Technology (4G) network, a 3rd Generation Mobile Communication Technology (3G) network, or a terminal in a future evolution network.

[0073] Specifically, the DC system control method includes the following steps:

[0074] Step 110, obtaining a DC power command value corresponding to the DC system;

[0075] Step 120: determining a DC current command value and a DC voltage command value corresponding to the DC system according to the DC power command value, wherein the DC current command value is not less than a minimum DC current limit value;

[0076] Step 130: Control the current control-end modular multilevel converter MMC in the DC system according to the DC current command value, and control the voltage control end MMC in the DC system according to the DC voltage command value, wherein the current control end MMC and / or the voltage control end MMC is a unidirectional current H-bridge submodule (Unidirectional Current H-bridge Submodule, UCH-SM)-based MMC (UCH-MMC).

[0077] According to some embodiments, Figure 2 FIG. 1 shows a schematic structural diagram of a DC system provided by an embodiment of the present disclosure. Figure 2As shown, both sides of the DC system are connected to the AC system. This AC system can be an AC grid or another AC system, such as a wind turbine, electric motor, or other three-phase generator or load. Transformers may or may not be present between the first and second MMCs and the AC system. The DC line in between can be any conductor, such as an overhead line, cable, or conventional low-, medium-, or high-voltage conductor.

[0078] In some embodiments, the first MMC is a current control terminal MMC, and the second MMC is a voltage control terminal MMC. Alternatively, the first MMC is a voltage control terminal MMC, and the second MMC is a current control terminal MMC.

[0079] In some embodiments, the current control terminal MMC refers to an MMC for controlling the DC current of the DC system, and the voltage control terminal MMC refers to an MMC for controlling the DC voltage of the DC system.

[0080] According to some embodiments, Figure 3 FIG. 1 shows a structural diagram of a UCH-MMC provided by an embodiment of the present disclosure. Figure 3 As shown, the UCH-MMC includes: a first phase unit, a second phase unit, and a third phase unit. Each phase unit includes an upper bridge arm and a lower bridge arm, the upper bridge arm includes a series-connected upper bridge arm submodule string and an upper bridge arm inductor, and the lower bridge arm includes a series-connected lower bridge arm submodule string and a lower bridge arm inductor;

[0081] Wherein, the positive electrode of the upper bridge arm submodule string is connected to the DC positive bus, the first end of the upper bridge arm inductor is connected to the negative electrode of the upper bridge arm submodule string, the negative electrode of the lower bridge arm submodule string is connected to the DC negative bus, the first end of the lower bridge arm inductor is connected to the positive electrode of the lower bridge arm submodule string, and the second end of the upper bridge arm inductor and the second end of the lower bridge arm inductor are connected to the AC neutral point;

[0082] The upper bridge arm sub-module string and the lower bridge arm sub-module string each include n cascaded UCH-SMs, where n≥2.

[0083] The direction of the current in each phase unit is from the positive pole of the upper bridge arm submodule string to the negative pole of the lower bridge arm submodule string. The first phase unit is connected to the AC neutral point A, and the current i a Input to AC neutral point A. The second phase unit is connected to AC neutral point B and the current i b Input to AC neutral point B. The third phase unit is connected to AC neutral point C and the current i c Input to AC neutral point C. The DC positive bus is the DC positive terminal of the UCH-MMC. The DC negative bus is the DC negative terminal of the UCH-MMC.

[0084] According to some embodiments, Figure 4FIG. 1 shows a schematic diagram of the structure of a UCH-SM provided by an embodiment of the present disclosure. Figure 4 As shown, the UCH-SM includes a first switch S1, a second switch S2, a first diode D1, a second diode D2 and a DC capacitor U c The collector of the first switch S1 and the cathode of the first diode D1 are the input terminals of UCH-SM. The emitter of the second switch S2 and the anode of the second diode D2 are the output terminals of UCH-SM. c The positive electrode is connected to the collector of the second switch S2 and the positive electrode of the first diode D1, and the DC capacitor U c The cathode of the diode D2 is connected to the emitter of the first switch S1 and the cathode of the second diode D2.

[0085] Among them, the current i in UCH-SM arm The direction is from the input end of UCH-SM to the output end of UCH-SM.

[0086] In some embodiments, the switches provided in the embodiments of the present disclosure, such as the first switch S1 and the second switch S2, are not specifically of a fixed type. Such switch types include, but are not limited to, bipolar junction transistors (BJTs), gate turn-off thyristors (GTOs), insulated gate bipolar transistors (IGBTs), integrated gate commutated thyristors (IGCTs), and metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0087] It is easy to understand that the related art proposes a constant DC current mode, which requires the DC current of the MMC to always maintain the rated value, and the DC voltage to continuously change to achieve DC power regulation. In this operating mode, the magnitude of the DC voltage is proportional to the DC power. In particular, when the DC power is 0, the DC voltage of the MMC drops to 0, while the DC current remains at the rated value. Although this method solves the problem of DC current existence to a certain extent, the operation mode of maintaining the rated DC current regardless of the DC power significantly increases the operating losses of the DC line and the converter, and brings new economic problems to the converter.

[0088] According to some embodiments, the DC current command value is not specifically a fixed value. For example, when the DC power command value changes, the DC current command value may change. When the DC system changes, the DC current command value may also change.

[0089] According to some embodiments, the DC voltage command value is not specifically a fixed value. For example, when the DC power command value changes, the DC voltage command value may change. When the DC system changes, the DC voltage command value may also change.

[0090] According to some embodiments, the minimum DC current limit is determined by the rated reactive power of the MMC. This minimum DC current limit is not specifically a fixed limit. For example, the minimum DC current limit may change when the MMC changes. The minimum DC current limit may also change when a limit modification instruction for the minimum DC current limit is received.

[0091] In some embodiments, when the DC power command value changes, if the DC voltage command value is greater than the minimum DC current limit, the DC voltage command value and the DC current command value may change. For example, when the DC power command value increases, the DC voltage command value and the DC current command value may both increase. When the DC power command value decreases, the DC voltage command value and the DC current command value may both decrease.

[0092] In some embodiments, when the DC power command value changes, if the DC voltage command value is equal to the minimum DC current limit, the DC voltage command value and / or the DC current command value may change. For example, when the DC power command value increases, both the DC voltage command value and the DC current command value may increase. When the DC power command value decreases, the DC voltage command value may decrease, while the DC current command value remains at the minimum DC current limit.

[0093] It's easy to understand that the related art proposes a constant DC current mode, which requires the MMC's DC current to maintain a rated value and the DC voltage to continuously vary to achieve DC power regulation. In this operating mode, the DC voltage is proportional to the DC power. Specifically, when the DC power is zero, the MMC's DC voltage drops to zero, while the DC current remains at the rated value. While this approach addresses the issue of DC current existence to some extent, maintaining the rated DC current regardless of the DC power significantly increases the operating losses of the DC line and converter, and introduces new economic issues for the converter. However, the disclosed embodiments reduce the operating losses of the DC line and MMC by controlling the DC current command value to decrease when the DC power command value decreases. Furthermore, by setting a minimum DC current limit, it ensures that the DC current will not fall below this minimum limit during normal DC system operation, thereby reducing the operating losses of the DC system and MMC while ensuring the MMC's reactive power exchange capability.

[0094] In the embodiment of the present disclosure, the current control terminal MMC is a UCH-MMC, and the voltage control terminal MMC is a DC voltage variable MMC;

[0095] or,

[0096] The current control terminal MMC is a DC voltage variable MMC, and the voltage control terminal MMC is a UCH-MMC.

[0097] In the embodiment of the present disclosure, the DC voltage variable MMC is any one of UCH-MMC, full-bridge MMC, and full-half-bridge hybrid MMC.

[0098] In the embodiment of the present disclosure, determining the DC current command value and the DC voltage command value corresponding to the DC system according to the DC power command value includes:

[0099] Determine the DC current command value according to formula (1):

[0100]

[0101] Among them, i * dc is the DC current command value, P is the DC power command value, Q N is the rated reactive power, U acN is the rated AC phase voltage RMS value, h is the redundancy factor, and the h value is equal to the maximum possible total harmonic distortion rate when the DC system is running.

[0102] Determine the DC voltage command value according to formula (2):

[0103]

[0104] Among them, u * dc is the DC voltage command value, P is the DC power command value, Q N is the rated reactive power, U acN is the rated AC phase voltage RMS value, h is the redundancy factor, and the h value is equal to the maximum possible total harmonic distortion rate when the DC system is running.

[0105] According to some embodiments, when the DC current command value is determined according to formula (1), Q N The rated reactive power of the current control terminal MMC is used, U acN The rated AC phase voltage effective value of the current control terminal MMC is used. When the DC voltage command value is determined according to formula (2), Q N The rated reactive power of the voltage control terminal MMC is used, U acN The rated AC phase RMS voltage of the voltage control terminal MMC is used.

[0106] In some embodiments, when the MMC adopts the UCH-MMC, assuming that the DC power command value, AC reactive power actual value, rated AC phase voltage effective value, and redundancy coefficient of the UCH-MMC are known, the AC phase current effective value of the UCH-MMC can be determined according to formula (3):

[0107]

[0108] Among them, I ac is the effective value of AC phase current, P is the DC power command value, Q is the actual value of AC reactive power, U acN is the rated AC phase voltage effective value.

[0109] It is easy to understand that the DC voltage of the UCH-MMC needs to satisfy formula (4) to ensure that the bridge arm current of the UCH-MMC is unidirectional:

[0110]

[0111] Among them, I ac is the effective value of the AC phase current, i dc is the actual value of DC current, and h is the redundancy coefficient.

[0112] In some embodiments, substituting formula (3) into formula (4) yields:

[0113]

[0114] In which, let the actual value of AC reactive power Q be equal to the rated reactive power Q N , we can get formula (1).

[0115] According to some embodiments, the relationship among the DC voltage, DC current, and DC power command value is shown in formula (6):

[0116]

[0117] Among them, i dc is the actual value of DC current, P is the DC power command value, u dc is the actual value of DC voltage.

[0118] Among them, in steady state, the actual value of DC current i dc Equal to the specified value of DC current i * dc Therefore, substituting formula (1) into formula (6) yields formula (2).

[0119] In an embodiment of the present disclosure, controlling a current control-end modular multilevel converter MMC in a DC system according to a DC current command value includes:

[0120] According to the DC current command value, a DC current inner loop controller is used to perform DC current closed-loop control on the current control terminal MMC to obtain a DC component of the first bridge arm voltage reference value;

[0121] Obtaining a d-axis current command value and a q-axis current command value, performing AC current closed-loop control on the current control terminal MMC using an AC current inner-loop controller, and obtaining an AC component of a first bridge arm voltage reference value;

[0122] The first bridge arm voltage reference value is determined according to the DC component of the first bridge arm voltage reference value and the AC component of the first bridge arm voltage reference value, so as to control the bridge arm output voltage of the current control terminal MMC.

[0123] In an embodiment of the present disclosure, controlling the voltage control terminal MMC in the DC system according to the DC voltage command value includes:

[0124] According to the DC voltage command value, the DC voltage outer loop controller is used to perform DC voltage closed loop control on the voltage control terminal MMC to obtain the DC voltage and current command value;

[0125] According to the DC voltage and current command values, a DC current inner loop controller is used to perform DC current closed-loop control on the voltage control terminal MMC to obtain a DC component of the second bridge arm voltage reference value;

[0126] Obtaining the d-axis current command value and the q-axis current command value, and using the AC current inner loop controller to perform AC current closed-loop control on the voltage control terminal MMC to obtain the AC component of the second bridge arm voltage reference value;

[0127] The second bridge arm voltage reference value is determined according to the DC component of the second bridge arm voltage reference value and the AC component of the second bridge arm voltage reference value, so as to control the bridge arm output voltage of the voltage control terminal MMC.

[0128] According to some embodiments, the bridge arm voltage reference value in the first bridge arm voltage reference value and the second bridge arm voltage reference value includes a first upper bridge arm voltage reference value e * ap , the first lower bridge arm voltage reference value e * an , the second upper bridge arm voltage reference value e * bp , the second lower bridge arm voltage reference value e * bn , the third upper bridge arm voltage reference value e * cp and the third lower bridge arm voltage reference value e * cn .

[0129] In some embodiments, when determining the first bridge arm voltage reference value based on the DC component of the first bridge arm voltage reference value and the AC component of the first bridge arm voltage reference value, or when determining the second bridge arm voltage reference value based on the DC component of the second bridge arm voltage reference value and the AC component of the second bridge arm voltage reference value, the first bridge arm voltage reference value or the second bridge arm voltage reference value can be determined by linear operation.

[0130] According to some embodiments, the AC component e of the bridge arm voltage reference value provided by the embodiments of the present disclosure is * abc For example, the AC component of the first bridge arm voltage reference value and the AC component of the second bridge arm voltage reference value include the A phase AC component e * a 、B phase AC component e * b and C phase AC component e * c .

[0131] In the embodiment of the present disclosure, obtaining the d-axis current command value and the q-axis current command value includes:

[0132] The capacitor voltage outer loop controller is used to perform closed-loop control of the DC system capacitor voltage to obtain the d-axis current command value;

[0133] The reactive power outer loop controller is used to perform reactive power closed-loop control on the DC system to obtain the q-axis current command value.

[0134] According to some embodiments, when the d-axis current command value and the q-axis current command value are obtained and the AC current inner-loop controller is used to perform AC current closed-loop control on the current control terminal MMC, the capacitor voltage outer-loop controller is used to perform capacitor voltage closed-loop control on the current control terminal MMC, and the reactive power outer-loop controller is used to perform reactive power closed-loop control on the current control terminal MMC.

[0135] According to some embodiments, when the d-axis current command value and the q-axis current command value are obtained and the AC current inner-loop controller is used to perform AC current closed-loop control on the voltage control terminal MMC, the capacitor voltage outer-loop controller is used to perform capacitor voltage closed-loop control on the voltage control terminal MMC, and the reactive power outer-loop controller is used to perform reactive power closed-loop control on the voltage control terminal MMC.

[0136] In the embodiments of the present disclosure, the controllers provided in the embodiments of the present disclosure, such as the DC current inner loop controller, the AC current inner loop controller, the capacitor voltage outer loop controller, the reactive power outer loop controller, and the DC voltage outer loop controller, are not specifically fixed controllers. For example, the controller may be a proportional-integral (PI) controller.

[0137] According to some embodiments, Figure 5 FIG. 1 shows a controller block diagram of a current control terminal MMC provided by an embodiment of the present disclosure. Figure 5 As shown, first, according to the DC power command value P, the DC current command value i is calculated by formula (1): * dc The DC current command value i * dc The DC current inner loop controller sends the DC current command value i * dc And the actual value of DC current i returned by the measurement system dc , perform DC current closed-loop control on the current control terminal MMC to obtain the DC component e of the first bridge arm voltage reference value * dc At the same time, the capacitor voltage outer loop controller is used according to the capacitor voltage reference value U * cap and the actual value of the capacitor voltage U cap The capacitor voltage closed-loop control is performed on the current control terminal MMC to generate the d-axis current command value i * d ; Use reactive power outer loop controller according to AC reactive power command value Q * The reactive power closed-loop control is performed on the current control terminal MMC with the actual value Q of the AC reactive power to generate the q-axis current command value i * q; AC current inner loop controller according to the d-axis current command value i * d , actual value of d-axis current i d , q-axis current command value i * q and the actual value of the d-axis current i d , perform AC current closed-loop control on the current control terminal MMC to obtain the AC component e of the first bridge arm voltage reference value * abc Finally, according to the DC component e * dc and AC component e * abc , get the first bridge arm voltage reference value: the first upper bridge arm voltage reference value e * ap , the first lower bridge arm voltage reference value e * an , the second upper bridge arm voltage reference value e * bp , the second lower bridge arm voltage reference value e * bn , the third upper bridge arm voltage reference value e * cp and the third lower bridge arm voltage reference value e * cn .

[0138] According to some embodiments, Figure 6 FIG. 1 shows a controller block diagram of a voltage control terminal MMC provided by an embodiment of the present disclosure. Figure 6 As shown, first, according to the DC power command value P, the DC voltage command value u is calculated by formula (2): * dc , and the DC voltage command value u * dc The DC voltage outer loop controller sends the DC voltage command value u to the DC voltage outer loop controller. * dc and the actual value of DC voltage u dc Perform DC voltage closed-loop control on the voltage control terminal MMC to obtain the DC voltage and current command value i * dc1 The DC current inner loop controller is based on the DC voltage and current command value i * dc1 and the actual value of DC current i dc , perform DC current closed-loop control on the voltage control terminal MMC to obtain the DC component e of the second bridge arm voltage reference value * dc At the same time, the capacitor voltage outer loop controller is used according to the capacitor voltage reference value U *cap and the actual value of the capacitor voltage U cap The voltage control terminal MMC is used to perform closed-loop control of the capacitor voltage to generate the d-axis current command value i * d ; Use reactive power outer loop controller according to AC reactive power command value Q * The voltage control terminal MMC is controlled by the actual value of AC reactive power Q to generate the q-axis current command value i * q ; AC current inner loop controller according to the d-axis current command value i * d , actual value of d-axis current i d , q-axis current command value i * q and the actual value of the d-axis current i d , perform AC current closed-loop control on the voltage control terminal MMC to obtain the AC component e of the second bridge arm voltage reference value * abc Finally, according to the DC component e * dc and AC component e * abc , get the second bridge arm voltage reference value: the first upper bridge arm voltage reference value e * ap , the first lower bridge arm voltage reference value e * an , the second upper bridge arm voltage reference value e * bp , the second lower bridge arm voltage reference value e * bn , the third upper bridge arm voltage reference value e * cp and the third lower bridge arm voltage reference value e * cn .

[0139] In summary, the method provided in the embodiment of the present disclosure obtains a DC power command value corresponding to the DC system; determines a DC current command value and a DC voltage command value corresponding to the DC system according to the DC power command value, wherein the DC current command value is not less than the minimum DC current limit; controls the current control end modular multilevel converter MMC in the DC system according to the DC current command value, and controls the voltage control end MMC in the DC system according to the DC voltage command value, wherein the current control end MMC and / or the voltage control end MMC is a UCH-MMC based on a unidirectional current type H-bridge submodule. Therefore, by calculating the DC current command value and the DC voltage command value according to the DC power command value, and controlling the current control end MMC according to the DC current command value, and controlling the voltage control end MMC according to the DC voltage command value, the DC system can maintain a certain DC current when the DC power is very low, thereby ensuring that when the current control end MMC and / or the voltage control end MMC is a UCH-MMC, it has a certain reactive power exchange capacity, thereby improving the flexibility of DC system control. In addition, by setting a minimum DC current limit, it can be ensured that the DC current will not be lower than the minimum DC current limit when the DC system is operating normally, thereby reducing the operating losses of the DC system and the MMC while ensuring that the MMC has reactive power exchange capability.

[0140] In order to implement the above embodiments, the present disclosure further proposes a DC system control device.

[0141] Figure 7 A structural schematic diagram of a first DC system control device provided by an embodiment of the present disclosure is shown.

[0142] like Figure 7 As shown, a DC system control device 700 includes:

[0143] The command value acquisition module 710 is used to obtain the DC power command value corresponding to the DC system;

[0144] The command value determination module 720 is used to determine the DC current command value and DC voltage command value corresponding to the DC system according to the DC power command value, and the DC current command value is not less than the minimum DC current limit value;

[0145] The MMC control module 730 is configured to control the current control-end modular multilevel converter (MMC) in the DC system according to the DC current command value, and to control the voltage control end (MMC) in the DC system according to the DC voltage command value, wherein the current control end (MMC) and / or the voltage control end (MMC) are UCH-MMCs based on unidirectional current-type H-bridge submodules.

[0146] In the embodiments of the present disclosure, Figure 8FIG. 2 shows a schematic diagram of the structure of a second DC system control device provided by an embodiment of the present disclosure. Figure 8 As shown, the command value determination module 720 includes a DC control submodule 721, an AC control submodule 722, and a reference value determination submodule 723. The command value determination module 720 is used to control the current control end modular multilevel converter MMC in the DC system according to the DC current command value:

[0147] The DC control submodule 721 is configured to perform DC current closed-loop control on the current control terminal MMC using a DC current inner-loop controller according to the DC current command value, thereby obtaining a DC component of the first bridge arm voltage reference value;

[0148] The AC control submodule 722 is used to obtain the d-axis current command value and the q-axis current command value, and perform AC current closed-loop control on the current control terminal MMC using the AC current inner-loop controller to obtain the AC component of the first bridge arm voltage reference value;

[0149] The reference value determination submodule 723 is configured to determine the first bridge arm voltage reference value according to the DC component and the AC component of the first bridge arm voltage reference value, so as to control the bridge arm output voltage of the current control terminal MMC.

[0150] In the embodiments of the present disclosure, Figure 9 FIG. 1 is a schematic diagram showing the structure of a third DC system control device provided by an embodiment of the present disclosure. Figure 9 As shown, the command value determination module 720 includes a voltage control submodule 724, a DC control submodule 721, an AC control submodule 722, and a reference value determination submodule 723. The command value determination module 720 is used to control the voltage control terminal MMC in the DC system according to the DC voltage command value:

[0151] The voltage control submodule 724 is configured to perform DC voltage closed-loop control on the voltage control terminal MMC using a DC voltage outer-loop controller according to the DC voltage command value to obtain a DC voltage and current command value;

[0152] The DC control submodule 721 is configured to perform DC current closed-loop control on the voltage control terminal MMC using a DC current inner-loop controller according to the DC voltage and current command values, thereby obtaining a DC component of the second bridge arm voltage reference value.

[0153] The AC control submodule 722 is used to obtain the d-axis current command value and the q-axis current command value, and use the AC current inner loop controller to perform AC current closed-loop control on the voltage control terminal MMC to obtain the AC component of the second bridge arm voltage reference value;

[0154] The reference value determination submodule 723 is configured to determine the second bridge arm voltage reference value according to the DC component and the AC component of the second bridge arm voltage reference value, so as to control the bridge arm output voltage of the voltage control terminal MMC.

[0155] In the embodiment of the present disclosure, the AC control submodule 722 is used to obtain the d-axis current command value and the q-axis current command value, specifically to:

[0156] The capacitor voltage outer loop controller is used to perform closed-loop control of the DC system capacitor voltage to obtain the d-axis current command value;

[0157] The reactive power outer loop controller is used to perform reactive power closed-loop control on the DC system to obtain the q-axis current command value.

[0158] In the embodiment of the present disclosure, the DC current inner loop controller and the AC current inner loop controller are proportional-integral PI controllers.

[0159] In the embodiment of the present disclosure, the current control terminal MMC is a UCH-MMC, and the voltage control terminal MMC is a DC voltage variable MMC;

[0160] or,

[0161] The current control terminal MMC is a DC voltage variable MMC, and the voltage control terminal MMC is a UCH-MMC.

[0162] In the embodiment of the present disclosure, the DC voltage variable MMC is any one of UCH-MMC, full-bridge MMC, and full-half-bridge hybrid MMC.

[0163] In summary, in the device provided by the embodiment of the present disclosure, a direct current power command value corresponding to the direct current system is obtained through a command value acquisition module; a command value determination module determines a direct current command value and a direct current voltage command value corresponding to the direct current system based on the direct current power command value, wherein the direct current command value is not less than the direct current minimum limit; an MMC control module controls the current control end modular multilevel converter MMC in the direct current system according to the direct current command value, and controls the voltage control end MMC in the direct current system according to the direct voltage command value, wherein the current control end MMC and / or the voltage control end MMC is a UCH-MMC based on a unidirectional current-type H-bridge submodule. Therefore, by calculating the direct current command value and the direct current voltage command value according to the direct current power command value, and controlling the current control end MMC according to the direct current command value, and controlling the voltage control end MMC according to the direct voltage command value, the direct current system can maintain a certain direct current when the direct current power is very low, thereby ensuring that when the current control end MMC and / or the voltage control end MMC is a UCH-MMC, it has a certain reactive power exchange capacity, thereby improving the flexibility of direct current system control. In addition, by setting a minimum DC current limit, it can be ensured that the DC current will not be lower than the minimum DC current limit when the DC system is operating normally, thereby reducing the operating losses of the DC system and the MMC while ensuring that the MMC has reactive power exchange capability.

[0164] According to an embodiment of the present disclosure, the present disclosure also provides a terminal, a readable storage medium, and a computer program product.

[0165] Figure 10 1. A schematic block diagram of an example terminal 1000 that can be used to implement embodiments of the present disclosure is shown. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit implementations of the present disclosure described and / or claimed herein.

[0166] like Figure 10 As shown, terminal 1000 includes a computing unit 1001, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 1002 or a computer program loaded from a storage unit 1008 into a random access memory (RAM) 1003. Various programs and data required for the operation of terminal 1000 can also be stored in RAM 1003. Computing unit 1001, ROM 1002, and RAM 1003 are connected to each other via a bus 1004. An input / output (I / O) interface 1005 is also connected to bus 1004.

[0167] Multiple components in terminal 1000 are connected to I / O interface 1005, including: an input unit 1006, such as a keyboard, mouse, etc.; an output unit 1007, such as various types of displays, speakers, etc.; a storage unit 1008, such as a magnetic disk, optical disk, etc.; and a communication unit 1009, such as a network card, modem, wireless communication transceiver, etc. The communication unit 1009 allows terminal 1000 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0168] The computing unit 1001 can be any general-purpose and / or specialized processing component with processing and computing capabilities. Some examples of the computing unit 1001 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 1001 performs the various methods and processes described above, such as the DC system control method. For example, in some embodiments, the DC system control method can be implemented as a computer software program tangibly embodied in a machine-readable medium, such as the storage unit 1008. In some embodiments, part or all of the computer program can be loaded and / or installed on the terminal 1000 via the ROM 1002 and / or the communication unit 1009. When the computer program is loaded into the RAM 1003 and executed by the computing unit 1001, one or more steps of the DC system control method described above can be performed. Alternatively, in other embodiments, the computing unit 1001 may be configured to execute the DC system control method in any other appropriate manner (for example, by means of firmware).

[0169] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system-on-chip systems (SOCs), programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0170] The program code for implementing the method of the present disclosure can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the program code is executed by the processor or controller, the functions / operations specified in the flow chart and / or block diagram are implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or terminal.

[0171] In the context of the present disclosure, a machine-readable medium can be a tangible medium that can contain or store a program for use by or in conjunction with an instruction execution system, device or equipment. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium can include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0172] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0173] The systems and techniques described herein can be implemented in a computing system that includes backend components (e.g., as a data terminal), or a computing system that includes middleware components (e.g., an application terminal), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with embodiments of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), the Internet, and a blockchain network.

[0174] A computer system may include clients and terminals. The clients and terminals are generally remote from each other and typically interact via a communication network. This client-terminal relationship is established by computer programs running on the respective computers, creating a client-terminal relationship. The terminal may be a cloud terminal, also known as a cloud computing terminal or cloud host. This is a host product within a cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosts and Virtual Private Server (VPS) services. The terminal may also be a terminal in a distributed system or a terminal integrated with blockchain.

[0175] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved. This is not limited herein.

[0176] The above specific embodiments do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure shall be included within the scope of protection of this disclosure.

Claims

1. A DC system control method, characterized in that: include: Obtain the DC power command value corresponding to the DC system; According to the DC power command value, a DC current command value and a DC voltage command value corresponding to the DC system are determined, wherein the DC current command value is not less than the minimum DC current limit value, wherein the DC current command value is determined according to formula (1), and the DC voltage command value is determined according to formula (2): （1） （2） in, i * dc is the DC current command value, u * dc is the DC voltage command value, P is the DC power command value, Q N is the rated reactive power, U acN is the rated AC phase voltage effective value, h is the redundancy coefficient, h The value is equal to the maximum possible total harmonic distortion rate when the DC system is running; The current control end modular multilevel converter MMC in the DC system is controlled according to the DC current command value, and the voltage control end MMC in the DC system is controlled according to the DC voltage command value, wherein the current control end MMC and / or the voltage control end MMC is a UCH-MMC based on a unidirectional current-type H-bridge submodule.

2. The method according to claim 1, wherein The controlling of the current control end modular multilevel converter MMC in the DC system according to the DC current command value includes: According to the DC current command value, a DC current inner loop controller is used to perform DC current closed-loop control on the current control terminal MMC to obtain a DC component of the first bridge arm voltage reference value; Obtaining a d-axis current command value and a q-axis current command value, and performing AC current closed-loop control on the current control terminal MMC using an AC current inner-loop controller to obtain an AC component of the first bridge arm voltage reference value; The first bridge arm voltage reference value is determined according to the DC component of the first bridge arm voltage reference value and the AC component of the first bridge arm voltage reference value, so as to control the bridge arm output voltage of the current control terminal MMC.

3. The method according to claim 1, wherein The controlling the voltage control terminal MMC in the DC system according to the DC voltage command value includes: According to the DC voltage command value, a DC voltage outer loop controller is used to perform DC voltage closed-loop control on the voltage control terminal MMC to obtain a DC voltage and current command value; According to the DC voltage and current command value, a DC current inner loop controller is used to perform DC current closed-loop control on the voltage control terminal MMC to obtain a DC component of the second bridge arm voltage reference value; Obtaining a d-axis current command value and a q-axis current command value, and performing AC current closed-loop control on the voltage control terminal MMC using an AC current inner-loop controller to obtain an AC component of the second bridge arm voltage reference value; The second bridge arm voltage reference value is determined according to the DC component of the second bridge arm voltage reference value and the AC component of the second bridge arm voltage reference value, so as to control the bridge arm output voltage of the voltage control terminal MMC.

4. The method according to claim 2 or 3, wherein: The obtaining of the d-axis current command value and the q-axis current command value includes: Performing closed-loop control of the capacitor voltage on the DC system using a capacitor voltage outer-loop controller to obtain a d-axis current command value; The reactive power outer loop controller is used to perform reactive power closed loop control on the DC system to obtain a q-axis current command value.

5. The method according to claim 2 or 3, wherein: The DC current inner loop controller and the AC current inner loop controller are proportional-integral PI controllers.

6. The method according to claim 1, wherein The current control terminal MMC is a UCH-MMC, and the voltage control terminal MMC is a DC voltage variable MMC; or, The current control end MMC is the DC voltage variable MMC, and the voltage control end MMC is the UCH-MMC.

7. The method according to claim 6, wherein The DC voltage variable MMC is any one of UCH-MMC, full-bridge MMC, and full-half-bridge hybrid MMC.

8. A DC system control device, characterized in that: include: The command value acquisition module is used to obtain the DC power command value corresponding to the DC system; The command value determination module is used to determine the DC current command value and DC voltage command value corresponding to the DC system according to the DC power command value, wherein the DC current command value is not less than the minimum DC current limit value, wherein the DC current command value is determined according to formula (1), and the DC voltage command value is determined according to formula (2): （1） （2） in, i * dc is the DC current command value, u * dc is the DC voltage command value, P is the DC power command value, Q N is the rated reactive power, U acN is the rated AC phase voltage effective value, h is the redundancy coefficient, h The value is equal to the maximum possible total harmonic distortion rate when the DC system is running; An MMC control module is configured to control a current control-end modular multilevel converter MMC in the DC system according to the DC current command value, and to control a voltage control end MMC in the DC system according to the DC voltage command value, wherein the current control end MMC and / or the voltage control end MMC is a UCH-MMC based on a unidirectional current-type H-bridge submodule.

9. A terminal comprising: at least one processor; as well as a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium storing computer instructions, wherein: The computer instructions are used to cause the computer to execute the method according to any one of claims 1 to 7.

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