A control method, device and equipment for realizing flexible DC power reversal

Abstract

The present application relates to a control method, device and equipment for realizing flexible direct current power reversal. The method includes setting the control mode of the first converter station to a fixed direct current voltage control mode and the control mode of the second converter station to a fixed active power control mode before responding to a power reversal instruction; obtaining the alternating current voltage of the first converter station and the second converter station and determining the alternating current fault position of the double-terminal direct current transmission system according to the alternating current voltage, and adjusting the high margin control parameters of the fixed active power control mode according to the alternating current fault position; responding to the power reversal instruction, controlling the double-terminal direct current transmission system to perform power reversal according to the power reversal rule according to the power rate and the power reference value. The method ensures the safe operation of the system by fixing the control mode of the converter station in the system and adjusting the high margin control parameters of the fixed active power control mode according to the alternating current fault position; after responding to the power reversal instruction, the power reversal rule control system is adopted to realize power reversal, which is efficient and simple.

Description

Technical Field

[0001] The present application relates to the field of direct current transmission technology, and in particular to a control method, device and equipment for realizing flexible direct current power reversal. Background Art

[0002] Compared with conventional DC transmission technology based on semi-controlled devices such as thyristors, flexible DC using fully controlled devices such as IGBT has the advantages of independent and flexible regulation of active and reactive power, no need for AC filters, small footprint, and the ability to supply power to passive systems. It has become a rapidly and widely used transmission method.

[0003] With the development of science and technology, the power control of power systems requires flexibility. As a large-capacity power transmission channel, flexible direct current has higher requirements for its power reversal function. At present, in terms of active power control of flexible direct current, the power reversal control function is rarely implemented in direct current transmission projects, or the implementation method adopts multiple steps, the operation is complicated and inefficient, and there is no fast, efficient and easy-to-operate power reversal control function. The power reversal operation of the existing two-terminal direct current transmission system is: first manually reduce the current power to around 0MW, then manually operate the setting to change the power transmission direction, and finally input the reverse direction power reference value to achieve power reversal. However, the power reversal operation of the current two-terminal direct current transmission system does not consider the adaptability of the AC fault ride-through strategy when the DC is running in different power directions. Summary of the invention

[0004] The embodiments of the present application provide a control method, device and equipment for realizing flexible DC power reversal, which are used to solve the technical problems of low efficiency and complex operation in the existing flexible DC power reversal.

[0005] In order to achieve the above objectives, the embodiments of the present application provide the following technical solutions:

[0006] On the one hand, a control method for realizing flexible direct current power reversal is provided, which is applied to a double-terminal direct current transmission system, wherein the double-terminal direct current transmission system includes a first converter station and a second converter station connected to the first converter station, and the control method includes the following steps:

[0007] Before responding to the power reversal instruction, the first converter station and the second converter station are set to a fixed control mode, the control mode of the first converter station is set to a fixed DC voltage control mode, and the control mode of the second converter station is set to a fixed active power control mode;

[0008] Acquiring AC voltages of the first converter station and the second converter station, determining an AC fault position of the double-terminal direct current transmission system according to the AC voltages of the first converter station and the second converter station, and adjusting a high margin control parameter of the fixed active power control mode according to the AC fault position;

[0009] In response to a power reversal instruction, a power rate and a power reference value are acquired, and a double-terminal direct current transmission system is controlled to perform power reversal according to a power reversal rule based on the power rate and the power reference value.

[0010] Preferably, adjusting the high margin control parameter of the fixed active power control mode according to the AC fault location includes:

[0011] If the AC fault location is at the fixed active power side of the double-terminal DC power transmission system, adjusting the high margin control parameter of the fixed active power control mode to a first threshold;

[0012] If the AC fault location is at the constant DC voltage side of the double-terminal DC power transmission system, the high margin control parameter of the constant active power control mode is adjusted to a second threshold.

[0013] Preferably, the power reversal rule comprises: obtaining a target reverse power value, and performing power reversal transmission power at the power rate according to the power reversal instruction.

[0014] Preferably, performing power reversal and transmitting power at the power rate according to the power reversal instruction includes:

[0015] If the power reversal instruction is a positive power transmission, controlling the DC power to increase from zero to the power reference value within the first time according to the power rate;

[0016] If the power reversal instruction is a negative power transmission, the DC power is controlled to decrease from the power reference value to the target reverse power value within a second time according to the power rate.

[0017] Preferably, if the power reference value is 1000 MW, the first time is 10 minutes, the second time is 20 minutes, and the power rate is 100 MW / min.

[0018] On the other hand, a control device for realizing flexible direct current power reversal is provided, which is applied to a double-terminal direct current power transmission system, wherein the double-terminal direct current power transmission system includes a first converter station and a second converter station connected to the first converter station, and the control device includes a mode fixing module, a parameter adjustment module and a power reversal execution module;

[0019] The mode fixing module is used to set the first converter station and the second converter station to a fixed control mode before responding to the power reversal instruction, the control mode of the first converter station is set to a fixed DC voltage control mode, and the control mode of the second converter station is set to a fixed active power control mode;

[0020] The parameter adjustment module is used to obtain the AC voltages of the first converter station and the second converter station, determine the AC fault position of the double-terminal direct current transmission system according to the AC voltages of the first converter station and the second converter station, and adjust the high margin control parameters of the fixed active power control mode according to the AC fault position;

[0021] The power reversal execution module is used to respond to the power reversal instruction, obtain the power rate and the power reference value, and control the double-terminal direct current transmission system to perform power reversal according to the power rate and the power reference value in accordance with the power reversal rule.

[0022] Preferably, the parameter adjustment module is further used to adjust the high margin control parameter of the fixed active power control mode to a first threshold value according to that the AC fault location is the fixed active power side of the double-terminal DC transmission system; and adjust the high margin control parameter of the fixed active power control mode to a second threshold value according to that the AC fault location is the fixed DC voltage side of the double-terminal DC transmission system.

[0023] Preferably, the power reversal rule comprises: obtaining a target reverse power value, and performing power reversal transmission power at the power rate according to the power reversal instruction.

[0024] Preferably, performing power reversal and transmitting power at the power rate according to the power reversal instruction includes:

[0025] If the power reversal instruction is a positive power transmission, controlling the DC power to increase from zero to the power reference value within the first time according to the power rate;

[0026] If the power reversal instruction is a negative power transmission, the DC power is controlled to decrease from the power reference value to the target reverse power value within a second time according to the power rate.

[0027] In another aspect, a terminal device is provided, comprising a processor and a memory;

[0028] The memory is used to store program codes and transmit the program codes to the processor;

[0029] The processor is used to execute the above-mentioned control method for realizing flexible DC power reversal according to the instructions in the program code.

[0030] The present application provides a control method, device and equipment for realizing flexible direct current power reversal. The method comprises, before responding to a power reversal instruction, setting the control mode of a first converter station in a double-terminal direct current transmission system to a fixed direct current voltage control mode, and setting the control mode of a second converter station to a fixed active power control mode; obtaining the alternating current voltages of the first converter station and the second converter station, determining the alternating current fault position of the double-terminal direct current transmission system according to the alternating current voltages of the first converter station and the second converter station, and adjusting the high margin control parameters of the fixed active power control mode according to the alternating current fault position; in response to the power reversal instruction, obtaining a power rate and a power reference value, and controlling the double-terminal direct current transmission system to perform power reversal according to a power reversal rule according to the power rate and the power reference value. It can be seen from the above technical solutions that the embodiments of the present application have the following advantages: the control method for realizing flexible DC power reversal first fixes the control mode of the converter station in the double-terminal DC transmission system, and then adjusts the high margin control parameters of the active power control mode according to the AC fault location to ensure the safe operation of the system; in response to the power reversal instruction, the double-terminal DC transmission system is controlled to perform power reversal by adopting the power reversal rule according to the above settings, which is efficient and simple, and does not require manual operation to reverse the control mode and power direction of the converter station, thereby solving the technical problems of low efficiency and complex operation in the existing implementation of flexible DC power reversal. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 A flowchart of the steps of the control method for realizing flexible DC power reversal described in an embodiment of the present application;

[0033] Figure 2 A topological diagram of a double-terminal direct current transmission system in a control method for realizing flexible direct current power reversal described in an embodiment of the present application;

[0034] Figure 3 A schematic diagram of a DC voltage margin control strategy in a control method for realizing flexible DC power reversal described in an embodiment of the present application;

[0035] Figure 4 This is a framework flow chart of a control device for realizing flexible DC power reversal according to an embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the embodiments described below are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] In the description of the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0038] In the embodiments of the present application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0039] The embodiments of the present application provide a control method, device and equipment for realizing flexible DC power reversal, which can realize the power rapid reversal function of the steady-state control of the double-terminal DC transmission system, and at the same time realize the control of the dynamic characteristics of dynamic processes such as AC faults, and is used to solve the technical problems of low efficiency and complex operation in the existing flexible DC power reversal.

[0040] Embodiment 1:

[0041] Figure 1 This is a flowchart of the steps of the control method for realizing flexible DC power reversal described in an embodiment of the present application. Figure 2 This is a topological diagram of a two-terminal direct current transmission system in a control method for realizing flexible direct current power reversal described in an embodiment of the present application.

[0042] like Figure 1 As shown, an embodiment of the present application provides a control method for realizing flexible DC power reversal, which is applied to a double-terminal DC transmission system, wherein the double-terminal DC transmission system includes a first converter station and a second converter station connected to the first converter station, and includes the following steps:

[0043] S1. Before responding to the power reversal instruction, the first converter station and the second converter station are set to fixed control modes, the control mode of the first converter station is set to a fixed DC voltage control mode, and the control mode of the second converter station is set to a fixed active power control mode.

[0044] It should be noted that in step S1, the control modes of the two converter stations in the two-terminal DC transmission system are fixed, so that the converter stations do not change with the change of power direction during the power reversal process of the two-terminal DC transmission system. Compared with the existing flexible DC power reversal that follows the change of power direction, the existing flexible DC power reversal only controls the control mode of the rectifier station and the inverter station unchanged. Regardless of whether the power transmission of the two-terminal DC transmission system is forward or reverse, the rectifier station of the two-terminal DC transmission system is always in the DC voltage control mode, and the inverter station of the two-terminal DC transmission system is always in the active power control mode. This control mode brings inconvenience to the actual flexible transmission project operation. In this embodiment, regardless of how the power direction of the two-terminal DC transmission system changes, the control mode of the first converter station is always fixed to the fixed DC voltage control mode, and the control mode of the second converter station is set to the fixed active power control mode.

[0045] like Figure 2 As shown, in an embodiment of the present application, a double-terminal direct current transmission system includes a first converter and a second converter connected to the first converter, the first converter is also connected to a first transformer, and the second converter is also connected to a second transformer.

[0046] It should be noted that the power transmission direction from the first converter to the second converter is the positive power transmission direction, also known as the power forward transmission direction; the power transmission direction from the second converter to the first converter is the negative power transmission direction, also known as the power reverse transmission direction. Regardless of how the power reversal is operated, the control mode of the first converter station on the double-terminal DC transmission system is always the fixed DC voltage control mode, and the control mode of the second converter station is always the fixed active power control mode, as shown in Table 1 below.

[0047] Table 1 is the relationship between power reversal and control mode

[0048] Power forward direction Power reverse direction First inverter Rectifier station: Constant DC voltage control mode Inverter station: fixed active power control mode Second inverter Inverter station: Constant DC voltage control mode Rectifier station: fixed active power control mode

[0049] S2. Obtain the AC voltages of the first converter station and the second converter station, determine the AC fault location of the double-terminal DC transmission system according to the AC voltages of the first converter station and the second converter station, and adjust the high margin control parameters of the active power control mode according to the AC fault location.

[0050] It should be noted that due to the control mode of the converter station in the fixed double-terminal DC transmission system, in order to adapt to the power reverse condition, when an AC fault occurs on the fixed DC voltage side of the inverter station in the double-terminal DC transmission system, to avoid overvoltage on the DC side causing damage to the equipment in the double-terminal DC transmission system or AC fault crossing failure tripping, it is necessary to optimize the high margin control parameters on the fixed active power control side. The high margin control parameters of the fixed active power control mode obtained by optimization can enable the double-terminal DC transmission system to start the DC voltage margin control of the fixed active power control mode as soon as possible to avoid overvoltage damage to power equipment. The control method for realizing flexible DC power reversal optimizes the high margin control parameters of the DC voltage of the converter station in the fixed active power control mode, so as to achieve power reversal and after the converter station control mode changes, the adaptability of the AC fault crossing control strategy is strong, ensuring the safe and reliable operation of DC.

[0051] S3. In response to the power reversal instruction, a power rate and a power reference value are obtained, and the double-terminal direct current transmission system is controlled to perform power reversal according to the power rate and the power reference value and the power reversal rule.

[0052] It should be noted that in step S3, after the two-terminal DC transmission system is set in step S1 and step S2, after the two-terminal DC transmission system is unlocked, the power reversal rule is used to control the two-terminal DC transmission system to perform power reversal. In this embodiment, the power reversal rule is used to increase and decrease the power according to the power rate, and the two-terminal DC transmission system is controlled to perform power reversal. Among them, during the DC operation of the two-terminal DC transmission system, the control method for realizing flexible DC power reversal can adjust the power reference value at any time, and can also change the positive and negative signs of the power reference value, and directly realize the reversal of DC power, without the need for manual operation to reduce the power to zero power, and then change the control mode of the two converter stations, and then perform power reversal, so as to realize the change of power value and direction, and there is no need to manually operate the control mode and power direction of the reverse converter station.

[0053] The present application provides a control method for realizing flexible direct current power reversal. The method includes, before responding to a power reversal instruction, setting the control mode of a first converter station in a double-terminal direct current transmission system to a fixed direct current voltage control mode, and setting the control mode of a second converter station to a fixed active power control mode; obtaining the alternating current voltages of the first converter station and the second converter station, determining the alternating current fault position of the double-terminal direct current transmission system according to the alternating current voltages of the first converter station and the second converter station, and adjusting the high margin control parameters of the fixed active power control mode according to the alternating current fault position; in response to the power reversal instruction, obtaining a power rate and a power reference value, and controlling the double-terminal direct current transmission system to perform power reversal according to a power reversal rule according to the power rate and the power reference value. The control method for realizing flexible direct current power reversal first fixes the control mode of the converter station in the double-terminal direct current transmission system, and then adjusts the high-margin control parameters of the active power control mode according to the AC fault position to ensure the safe operation of the system; in response to the power reversal instruction, the double-terminal direct current transmission system is controlled to perform power reversal by adopting the power reversal rule according to the above settings, which is efficient and simple, and does not require manual operation to reverse the control mode and power direction of the converter station, thereby solving the technical problems of low efficiency and complex operation in the existing realization of flexible direct current power reversal.

[0054] Figure 3 This is a schematic diagram of a DC voltage margin control strategy in a control method for realizing flexible DC power reversal described in an embodiment of the present application.

[0055] In one embodiment of the present application, adjusting the high margin control parameters of the active power control mode according to the AC fault location includes:

[0056] If the AC fault location is at the fixed active power side of the double-terminal DC transmission system, adjusting the high margin control parameter of the fixed active power control mode to a first threshold;

[0057] If the AC fault location is at the constant DC voltage side of the double-terminal DC transmission system, the high margin control parameter of the constant active power control mode is adjusted to a second threshold.

[0058] The first threshold is preferably 1.08 pu, and the second threshold is preferably 1.06 pu, where pu is the per-unit value of the DC voltage in the fixed active power control mode.

[0059] It should be noted that if Figure 3 As shown in the figure, the control method for realizing flexible DC power reversal determines the high margin control parameter U of the DC voltage on the active power side. dcrefHOptimize to avoid overvoltage. When a fault is detected on the fixed active power side of the double-terminal DC transmission system, the high margin control parameter is set to the first threshold; when a fault is detected on the fixed DC voltage side of the double-terminal DC transmission system, the high margin control parameter is set to the second threshold because the DC side of the double-terminal DC transmission system is more prone to overvoltage, so as to start the DC voltage margin control as soon as possible to avoid overvoltage damage to the power equipment of the double-terminal DC transmission system.

[0060] In an embodiment of the present application, the AC voltages of the first converter station and the second converter station are obtained, and the content of determining the AC fault location of the double-terminal DC transmission system according to the AC voltages of the first converter station and the second converter station includes: determining the AC fault location according to whether the AC voltage of the first converter station or the second converter station is less than a threshold voltage.

[0061] It should be noted that the threshold voltage is 0.9PU of the converter station, and the PU of 0.9PU refers to the voltage per unit value of the converter station. If the AC voltage of the first converter station is less than the threshold voltage, the AC fault location is on the constant DC voltage side of the double-terminal DC transmission system; if the AC voltage of the second converter station is less than the threshold voltage, the AC fault location is on the constant active power side of the double-terminal DC transmission system.

[0062] In one embodiment of the present application, the power reversal rule includes: obtaining a target reverse power value, performing power reversal and transmitting power at a power rate according to a power reversal instruction; performing power reversal and transmitting power at a power rate according to a power reversal instruction includes:

[0063] If the power reversal instruction is a positive power transmission, the DC power is controlled to increase from zero to the power reference value within the first time according to the power rate;

[0064] If the power reversal instruction is a negative power transmission, the DC power is controlled to decrease from the power reference value to the target reverse power value within the second time according to the power rate.

[0065] It should be noted that the first time can be selected as 10 minutes, the second time can be selected as 20 minutes, the power rate can be selected as 100MW / min, the power reference value can be selected as 1000MW, and the target reverse power value can be selected as -1000MW. The power reference value and the target reverse power value can be set to one, and the reversal of DC power is achieved by changing the positive and negative signs. In this embodiment, the power reference value is set to +1000MW, and the power rate is set to 100MW / min. Then, according to the power reversal instruction, the positive power is transmitted, and after 10 minutes, the power is automatically increased from 0MW to 1000MW. When power reversal is required, the target reverse power value is -1000MW, and the power rate is 100MW / min. Then, according to the power reversal instruction, the negative power is transmitted, and after 20 minutes, the power is automatically transmitted from 1000MW to -1000MW. During the power reversal process of the entire double-terminal DC transmission system, there is no need for manual operation to change the control mode of the two converter stations, nor is there any need to manually reduce the power to 0MW before reversing the power. The control method for realizing flexible DC power reversal has high power reversal efficiency.

[0066] Embodiment 2:

[0067] Figure 4 This is a framework flow chart of a control device for realizing flexible DC power reversal as described in an embodiment of the present application.

[0068] like Figure 4 As shown, an embodiment of the present application provides a control device for realizing flexible DC power reversal, which is applied to a double-terminal DC power transmission system. The double-terminal DC power transmission system includes a first converter station and a second converter station connected to the first converter station. The control device for realizing flexible DC power reversal includes a mode fixing module 10, a parameter adjustment module 20 and a power reversal execution module 30;

[0069] A mode fixing module 10, used for setting the first converter station and the second converter station to a fixed control mode before responding to a power reversal instruction, wherein the control mode of the first converter station is set to a fixed DC voltage control mode, and the control mode of the second converter station is set to a fixed active power control mode;

[0070] a parameter adjustment module 20, configured to obtain the AC voltages of the first converter station and the second converter station, determine the AC fault location of the double-terminal DC power transmission system according to the AC voltages of the first converter station and the second converter station, and adjust the high margin control parameters of the fixed active power control mode according to the AC fault location;

[0071] The power reversal execution module 30 is used to respond to the power reversal instruction, obtain the power rate and the power reference value, and control the double-terminal direct current transmission system to perform power reversal according to the power rate and the power reference value and the power reversal rule.

[0072] In the embodiment of the present application, the parameter adjustment module 20 is further used to adjust the high margin control parameter of the fixed active power control mode to a first threshold value according to that the AC fault location is the fixed active power side of the two-terminal DC transmission system; and to adjust the high margin control parameter of the fixed active power control mode to a second threshold value according to that the AC fault location is the fixed DC voltage side of the two-terminal DC transmission system; wherein pu is the per-unit value of the DC voltage in the fixed active power control mode.

[0073] In the embodiment of the present application, the power reversal rule includes: obtaining a target reverse power value, and performing power reversal transmission power at a power rate according to a power reversal instruction.

[0074] In an embodiment of the present application, performing power reversal and transmitting power at a power rate according to a power reversal instruction includes:

[0075] If the power reversal instruction is a positive power transmission, the DC power is controlled to increase from zero to the power reference value within the first time according to the power rate;

[0076] If the power reversal instruction is a negative power transmission, the DC power is controlled to decrease from the power reference value to the target reverse power value within the second time according to the power rate.

[0077] It should be noted that the module in the device of Example 2 corresponds to the steps in the method of Example 1. The content of the control method for realizing flexible DC power reversal has been described in detail in Example 1, and the content of the module in the device will not be described in detail in this Example 2.

[0078] Embodiment three:

[0079] An embodiment of the present application provides a terminal device, including a processor and a memory;

[0080] A memory, used for storing program codes and transmitting the program codes to a processor;

[0081] The processor is used to execute the above control method for realizing flexible DC power reversal according to the instructions in the program code.

[0082] It should be noted that the processor is used to execute the steps in the above-mentioned control method for realizing flexible DC power reversal according to the instructions in the program code. Alternatively, the processor implements the functions of each module / unit in the above-mentioned system / device embodiments when executing the computer program.

[0083] Exemplarily, the computer program may be divided into one or more modules / units, one or more modules / units are stored in a memory and executed by a processor to complete the present application. One or more modules / units may be a series of computer program instruction segments capable of completing a specific function, and the instruction segments are used to describe the execution process of the computer program in a terminal device.

[0084] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The terminal device may include, but is not limited to, a processor and a memory. Those skilled in the art will appreciate that this does not constitute a limitation on the terminal device, and may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the terminal device may also include input and output devices, network access devices, buses, etc.

[0085] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0086] The memory may be an internal storage unit of the terminal device, such as a hard disk or memory of the terminal device. The memory may also be an external storage device of the terminal device, such as a plug-in hard disk, a smart memory card (SmartMedia Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the terminal device. Furthermore, the memory may also include both an internal storage unit of the terminal device and an external storage device. The memory is used to store computer programs and other programs and data required by the terminal device. The memory may also be used to temporarily store data that has been output or is to be output.

[0087] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0088] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0089] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0090] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0091] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk.

[0092] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A control method for realizing flexible direct current power reversal, applied to a double-terminal direct current transmission system, the double-terminal direct current transmission system comprising a first converter station and a second converter station connected to the first converter station, characterized in that: The following steps are involved: Before responding to the power reversal instruction, the first converter station and the second converter station are set to a fixed control mode, the control mode of the first converter station is set to a fixed DC voltage control mode, and the control mode of the second converter station is set to a fixed active power control mode; Acquiring AC voltages of the first converter station and the second converter station, determining an AC fault position of the double-terminal direct current transmission system according to the AC voltages of the first converter station and the second converter station, and adjusting a high margin control parameter of the fixed active power control mode according to the AC fault position; In response to a power reversal instruction, a power rate and a power reference value are acquired, and a double-terminal direct current transmission system is controlled to perform power reversal according to a power reversal rule based on the power rate and the power reference value; The power reversal rule includes: obtaining a target reverse power value, performing power reversal and transmitting power at the power rate according to the power reversal instruction; performing power reversal and transmitting power at the power rate according to the power reversal instruction includes: If the power reversal instruction is a positive power transmission, controlling the DC power to increase from zero to the power reference value within the first time according to the power rate; If the power reversal instruction is a negative power transmission, the DC power is controlled to decrease from the power reference value to the target reverse power value within a second time according to the power rate.

2. The control method for realizing flexible DC power reversal according to claim 1, characterized in that: Adjusting the high margin control parameter of the fixed active power control mode according to the AC fault position includes: If the AC fault location is at the fixed active power side of the double-terminal DC power transmission system, adjusting the high margin control parameter of the fixed active power control mode to a first threshold; If the AC fault location is at the constant DC voltage side of the double-terminal DC power transmission system, the high margin control parameter of the constant active power control mode is adjusted to a second threshold.

3. The control method for realizing flexible DC power reversal according to claim 1, characterized in that: If the power reference value is 1000 MW, the first time is 10 minutes, the second time is 20 minutes, and the power rate is 100 MW / min.

4. A control device for realizing flexible direct current power reversal, applied to a double-terminal direct current transmission system, the double-terminal direct current transmission system comprising a first converter station and a second converter station connected to the first converter station, characterized in that: It includes a mode fixing module, a parameter adjusting module and a power reversal executing module; The mode fixing module is used to set the first converter station and the second converter station to a fixed control mode before responding to the power reversal instruction, the control mode of the first converter station is set to a fixed DC voltage control mode, and the control mode of the second converter station is set to a fixed active power control mode; The parameter adjustment module is used to obtain the AC voltages of the first converter station and the second converter station, determine the AC fault position of the double-terminal direct current transmission system according to the AC voltages of the first converter station and the second converter station, and adjust the high margin control parameters of the fixed active power control mode according to the AC fault position; The power reversal execution module is used to respond to the power reversal instruction, obtain the power rate and the power reference value, and control the double-terminal direct current transmission system to perform power reversal according to the power rate and the power reference value in accordance with the power reversal rule; The power reversal rule includes: obtaining a target reverse power value, performing power reversal and transmitting power at the power rate according to the power reversal instruction; performing power reversal and transmitting power at the power rate according to the power reversal instruction includes: If the power reversal instruction is a positive power transmission, controlling the DC power to increase from zero to the power reference value within the first time according to the power rate; If the power reversal instruction is a negative power transmission, the DC power is controlled to decrease from the power reference value to the target reverse power value within a second time according to the power rate.

5. The control device for realizing flexible DC power inversion according to claim 4, characterized in that: The parameter adjustment module is further configured to adjust the high margin control parameter of the fixed active power control mode to a first threshold value according to that the AC fault location is on the fixed active power side of the double-terminal DC transmission system; and adjust the high margin control parameter of the fixed active power control mode to a second threshold value according to that the AC fault location is on the fixed DC voltage side of the double-terminal DC transmission system.

6. A terminal device, characterized in that: including a processor and a memory; The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the control method for realizing flexible DC power reversal according to any one of claims 1 to 3 according to the instructions in the program code.

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