Control method and device of sea wind flexible direct current power transmission project, computer equipment and storage medium

Abstract

The invention provides a control method of a sea wind flexible direct current power transmission project. After fault signals of the land connected transformers are received, the maximum transmittable power is determined according to the number of the remaining land connected transformers, working condition grades are divided according to overload conditions, and data support and decision basis are provided for follow-up control; the maximum transmittable power smaller than the actual power of the current land station is transmitted to an automatic power generation control system of the offshore station, limited power control is triggered, power input is reduced from the source, and the situation that the power continuously exceeds the bearing capacity of a land connection transformer is avoided; and cutting off the offshore connection transformer of the offshore station according to a cutting mechanism corresponding to the working condition grade, further dynamically adjusting the output of offshore power generation power, and reducing the overall power transmission load of the system. According to the scheme, grading and classification protection of transmission power of the land connection transformer is achieved in an all-around mode, system faults caused by overload are effectively prevented, safe and stable operation of a sea wind flexible direct current transmission project is guaranteed, and system operation reliability and stability are improved.

Description

Technical Field

[0001] The present application relates to the technical field of flexible AC-DC systems, and particularly to a control method, device, computer device, and storage medium for a sea breeze flexible DC power transmission project. Background Art

[0002] Flexible DC power transmission is widely used in large-capacity and long-distance power transmission as well as new energy power plant grid connection due to advantages such as no commutation failure problem and active and reactive decoupled control. More and more new wind and solar energy power plants and flexible DC power transmission systems are put into operation. When a fault occurs in a sea breeze flexible DC power transmission project, there may be a risk of overload in the transformer branch of its onshore station, and a control method for eliminating the overload risk of the onshore station is needed. Summary of the Invention

[0003] The purpose of the present application aims to solve at least one of the above technical defects, and particularly provides a control method for a sea breeze flexible DC power transmission project that eliminates the overload risk of the onshore station.

[0004] In a first aspect, the present application provides a control method for a sea breeze flexible DC power transmission project. The sea breeze flexible DC power transmission project includes an offshore station and an onshore station connected to each other. The control method includes:

[0005] When receiving an onshore connection transformer fault signal, determining the maximum transmissible power according to the number of remaining onshore connection transformers, and determining the operating condition level according to the overload condition of the remaining onshore connection transformers;

[0006] If the maximum transmissible power is less than the actual power of the current onshore station, then transmit the maximum transmissible power to the automatic generation control system of the offshore station and set a power limit flag to trigger power limit control;

[0007] According to whether the power limit flag is lifted and the tripping mechanism corresponding to the operating condition level, trip the offshore connection transformer of the offshore station.

[0008] In one embodiment, determining the operating condition level according to the overload condition of the remaining onshore connection transformers includes:

[0009] If the number of onshore connection transformers changes from three to two and the overload condition exceeds a first threshold, then determine the operating condition level as the first level;

[0010] If the number of onshore connection transformers changes from two to one and the overload condition exceeds a second threshold, then determine the operating condition level as the second level; the second threshold is greater than the first threshold;

[0011] If the number of onshore connection transformers changes from three to one and the overload condition exceeds a third threshold, then determine the operating condition level as the first level; the third threshold is greater than the second threshold.

[0012] In one embodiment, if the operating condition level is the first level, according to whether the power limit identification is lifted and the tripping mechanism corresponding to the operating condition level, the offshore connection transformer of the offshore station is tripped, including:

[0013] If after the power limit control is triggered and within the first time threshold corresponding to the first level, the power limit identification is not lifted, then one preselected target offshore connection transformer in the offshore station is tripped.

[0014] In one embodiment, if the operating condition level is the second level, according to whether the power limit identification is lifted and the tripping mechanism corresponding to the operating condition level, the offshore connection transformer of the offshore station is tripped, including:

[0015] If after the power limit control is triggered and within the second time threshold corresponding to the second level, the power limit identification is not lifted, then one preselected target offshore connection transformer in the offshore station is tripped;

[0016] After the target offshore connection transformer is tripped, it is judged whether the power limit identification is still not lifted within the third time threshold corresponding to the second level;

[0017] If so, then the one with the minimum power among the remaining two offshore connection transformers in the offshore station is tripped.

[0018] In one embodiment, if the operating condition level is the third level, when transmitting the maximum transmissible power to the automatic generation control system of the offshore station and setting the power limit identification to trigger the power limit control, it further includes:

[0019] One preselected target offshore connection transformer in the offshore station is tripped.

[0020] In one embodiment, according to whether the power limit identification is lifted and the tripping mechanism corresponding to the operating condition level, the offshore connection transformer of the offshore station is tripped, including:

[0021] After the power limit control is triggered, it is judged whether the power limit identification is still not lifted within the fourth time threshold corresponding to the third level;

[0022] If so, then the one with the minimum power among the remaining two offshore connection transformers in the offshore station is tripped.

[0023] In one embodiment, tripping one preselected target offshore connection transformer in the offshore station includes:

[0024] Successively trigger the malfunction starting function of the grid side switch, the malfunction starting function of the valve side switch, lock the grid side switch and lock the valve side switch of the target offshore connection transformer.

[0025] In a second aspect, the present application provides a control device for a HVDC transmission project for sea breeze. The HVDC transmission project for sea breeze includes an offshore station and an onshore station connected to each other. The control device includes:

[0026] A fault response module, configured to determine the maximum transmissible power according to the number of remaining onshore connection transformers and determine the operating condition level according to the overload condition of the remaining onshore connection transformers when receiving an onshore connection transformer fault signal;

[0027] A power reduction module, configured to transmit the maximum transmissible power to the automatic generation control system of the offshore station and set a power limit flag to trigger power limit control when the maximum transmissible power is less than the actual power of the current onshore station;

[0028] An excision module, configured to excise the offshore connection transformer of the offshore station according to whether the power limit flag is lifted and the excision mechanism corresponding to the operating condition level.

[0029] In a third aspect, the present application provides a computer device, including one or more processors and a memory. Computer-readable instructions are stored in the memory. When the computer-readable instructions are executed by one or more processors, the steps of the control method for the HVDC transmission project for sea breeze in any of the above embodiments are executed.

[0030] In a fourth aspect, the present application provides a storage medium in which computer-readable instructions are stored. When the computer-readable instructions are executed by one or more processors, one or more processors are caused to execute the steps of the control method for the HVDC transmission project for sea breeze in any of the above embodiments.

[0031] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0032] After receiving the onshore connection transformer fault signal, this solution determines the maximum transmissible power according to the number of remaining onshore connection transformers and divides the operating condition level according to the overload condition, providing data support and decision-making basis for subsequent control; transmits the maximum transmissible power less than the actual power of the current onshore station to the automatic generation control system of the offshore station to trigger power limit control, reducing power input from the source and avoiding continuous power exceeding the bearing capacity of the onshore connection transformer; excises the offshore connection transformer of the offshore station according to the excision mechanism corresponding to the operating condition level, further dynamically adjusting the offshore power generation power output and reducing the overall power transmission load of the system. These steps are closely linked, from fault detection and parameter determination, to power generation power regulation, and then to equipment excision optimization, comprehensively realizing hierarchical and classified protection of the transmission power of the onshore connection transformer, effectively preventing system failures caused by overload, ensuring the safe and stable operation of the HVDC transmission project for sea breeze, and significantly improving the reliability and stability of system operation. Description of the Drawings

[0033] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0034] Figure 1 It is a schematic structural diagram of a sea breeze flexible DC transmission project provided by an embodiment of the present application;

[0035] Figure 2 It is a schematic flowchart of a control method for a sea breeze flexible DC transmission project provided by an embodiment of the present application;

[0036] Figure 3 It is a schematic flowchart of a switching mechanism corresponding to the second level in an embodiment of the present application;

[0037] Figure 4 It is an internal structural diagram of a computer device provided by an embodiment of the present application. Specific embodiments

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0039] The present application provides a control method for a sea breeze flexible DC transmission project. Please refer to Figure 1 , the sea breeze flexible DC transmission project includes a sea station and a land station connected to each other. The land station includes three land connection transformers, and the sea station includes three sea connection transformers. Please refer to Figure 2 , the control method includes steps S202 to S206.

[0040] S202, in the case of receiving a land connection transformer fault signal, determine the maximum transmissible power according to the number of remaining land connection transformers, and determine the operating condition level according to the overload condition of the remaining land connection transformers.

[0041] It can be understood that the onshore connection transformer refers to the transformer equipment that connects the onshore AC power grid and the flexible DC transmission system. Its function is to realize the conversion and transmission of AC and DC electrical energy, playing a key hub role in the entire transmission system. The onshore connection transformer fault signal is generated when one or more onshore connection transformers fail and need to be taken out of service. The maximum transmissible power refers to the maximum power value that the offshore HVDC transmission project can transmit from the offshore station to the onshore station under specific working conditions, considering the limit conditions of the onshore connection transformer. The working condition level is the level division of the operation state of the offshore HVDC transmission project based on the change in the number of onshore connection transformers. Different working condition levels correspond to different system operation characteristics and control strategies.

[0042] The fault of the onshore connection transformer will directly affect the power transmission capacity and system stability of the offshore HVDC transmission project. When a fault occurs in the onshore connection transformer, the number of remaining onshore connection transformers decreases, and the power transmission load they can withstand also changes accordingly. By calculating the number of remaining onshore connection transformers and combining their rated capacity, system operation parameters, etc., the maximum transmissible power of the current system can be determined. At the same time, since the severity of the overload situation will determine the bearing time of the onshore connection transformer, which will directly determine the timeliness of the control means adopted, it is necessary to use this as the division basis to divide different working condition levels, so as to select the corresponding tripping mechanism to control the overload situation.

[0043] S204, if the maximum transmissible power is less than the actual power of the current onshore station, then transmit the maximum transmissible power to the automatic generation control system of the offshore station and set a power limit flag to trigger power limit control.

[0044] It can be understood that the Automatic Generation Control (AGC) system is a system used by an offshore station to achieve automatic regulation and control of power generation. It can adjust the power generation of an offshore wind farm according to the received instructions to meet the operating requirements of the power transmission system and the power grid. The power limit identifier is a signal or flag used to mark that the system is in a power-limited state. When the system detects that power transmission is restricted, this identifier is set so that subsequent control modules and devices can identify and take corresponding measures. When the maximum transmissible power is less than the actual power of the current onshore station, it means that the transmission capacity of the power transmission system cannot meet the current power demand. Without intervention, the onshore transformer will be overloaded, affecting the safe and stable operation of the power transmission system. Transmitting the maximum transmissible power to the automatic generation control system of the offshore station, after receiving this instruction, the automatic generation control system can adjust the power generation of the offshore wind farm according to its own control logic. For example, when the maximum transmissible power is 500 MW and the actual power of the current onshore station is 600 MW, by transmitting 500 MW to the automatic generation control system, the automatic generation control system will reduce the power generation of the offshore wind farm and try to reduce it to below 500 MW.

[0045] S206. According to whether the power limit identifier is lifted and the disconnection mechanism corresponding to the operating condition level, disconnect the offshore connection transformer of the offshore station.

[0046] It can be understood that the disconnection mechanism is formulated for different operating condition levels and is used to determine the rules and procedures for disconnecting the offshore connection transformer of the offshore station. The offshore connection transformer is a transformer device that connects the offshore wind farm and the flexible DC power transmission system. Its function is similar to that of the onshore connection transformer, realizing the conversion and transmission of AC and DC electrical energy at the offshore station. Different operating condition levels reflect different operating states of the offshore HVDC transmission project and the overload degree of the onshore transformer. To ensure the safe and stable operation of the system under fault conditions, different disconnection mechanisms need to be adopted according to the operating condition levels, so that the load can be reasonably reduced within the overload intensity and duration that the onshore connection transformer can withstand, thereby solving the overload problem of the onshore connection transformer.

[0047] After receiving the fault signal of the onshore connection transformer, the scheme determines the maximum transmissible power based on the number of remaining onshore connection transformers, divides the operating condition levels according to the overload situation, and provides data support and decision-making basis for subsequent control; transmits the maximum transmissible power less than the actual power of the current onshore station to the automatic power generation control system of the offshore station, triggers the power limit control, reduces the power input from the source, and avoids the power continuously exceeding the carrying capacity of the onshore connection transformer; according to the disconnection mechanism corresponding to the operating condition level, disconnects the offshore connection transformer of the offshore station, further dynamically adjusts the offshore power generation power output, and reduces the overall power transmission load of the system. These steps are closely linked, from fault detection and parameter determination, to power generation power regulation, and then to equipment disconnection optimization, comprehensively realizing the hierarchical and classified protection of the transmission power of the onshore connection transformer, effectively preventing system failures caused by overload, ensuring the safe and stable operation of the HVDC transmission project for offshore wind power, and significantly improving the reliability and stability of system operation.

[0048] In one embodiment, determining the operating condition level according to the overload situation of the remaining onshore connection transformers includes: if the number of onshore connection transformers changes from three to two and the overload situation exceeds the first threshold, determining the operating condition level as the first level; if the number of onshore connection transformers changes from two to one and the overload situation exceeds the second threshold, determining the operating condition level as the second level; the second threshold is greater than the first threshold; if the number of onshore connection transformers changes from three to one and the overload situation exceeds the third threshold, determining the operating condition level as the first level; the third threshold is greater than the second threshold.

[0049] It can be understood that the operating condition level is a quantitative classification of the system operating status based on the overload condition of the onshore connection transformer. Its essence is an important parameter indicator that provides a key decision-making basis for the system control strategy. As the core equipment connecting the onshore AC power grid and the flexible DC transmission system, the overload condition of the onshore connection transformer directly affects the system's power transmission capacity, stability and operating risk level. Different operating condition levels correspond to different system operating characteristics. By clearly dividing the operating condition levels, differentiated control strategies can be implemented in a targeted manner to ensure that the system can maintain safe, stable and efficient operation under various fault or abnormal conditions. The reduction in the number of onshore connection transformers means a reduction in the system's power transmission paths and a decrease in transmission capacity. It will also change the system's power flow distribution and voltage stability. If three onshore transformers were operating at high loads before the fault, the power of the remaining onshore transformers will increase to take on the excess load. If this exceeds the first threshold, the system will face power transmission pressure, although it still has a certain degree of redundancy and adjustment capability. In this case, it will be determined to be level 1, which corresponds to a relatively mild control strategy to ensure normal system operation. If two onshore transformers were operating at high loads before the fault, when the number of onshore transformers is reduced from two to one, the power of the remaining onshore transformers will increase to take on the excess load. If this exceeds a second threshold (greater than the first), the risk of overload operation of the onshore connecting transformers will increase significantly. The second level is set to trigger stricter control measures to prevent system overload or instability. If the number of onshore transformers is reduced from three to one, the power of the remaining onshore transformers will increase to take on the excess load. If this exceeds a third threshold (greater than the second), the risk of overload operation of the onshore connecting transformers will increase sharply. The third level is set to immediately activate high-intensity protection and control mechanisms to ensure the safety of critical equipment and system stability. This overload-based classification of operating conditions provides a clear basis for subsequent control steps, such as power regulation and equipment removal, enabling each step to work together and effectively address system problems caused by onshore transformer failures.

[0050] Specifically, transformers all have a certain overload capacity. However, as the load increases, the time they can withstand will correspondingly shorten. Therefore, different means of load shedding with different efficiencies are required to address overload problems of different degrees. For example, 3p.u. / 2s means three times overload capacity for 2 seconds. The relevant information of the transformer will record the description of this type of overload capacity, such as 3p.u. / 2s, 2.3p.u. / 1min, 1.5p.u. / 15min, 1.2p.u. / 2 hours. Based on this, in this embodiment, the working condition levels are divided according to different overload situations and load-bearing capacities, so as to ensure safety according to the corresponding load shedding mechanism. Assume that the rated load of the onshore connection transformer is 667MW, ±200Mvar. If all three onshore connection transformers are operating at full load, the load to be transmitted is 2000MW, ±600Mvar. When a single group of onshore connection transformers fails and withdraws, the power of the remaining two groups of onshore connection transformers becomes 1000MW, ±300Mvar, and the apparent power is 1044MVA, reaching 1.45 times the rated value. This situation is the first level. When only two groups of onshore connection transformers are operating at full load, the maximum DC power is 1590MW. At this time, if one of the two branches of the onshore connection transformer fails and trips, the independent transformer branch needs to bear 1590MW, and the overload reaches 2.3 times the rated value. This situation is the second level. When all three onshore connection transformers are operating at full load, and two of them fail and withdraw, at this time, a single transformer needs to bear 2000MW. This situation is the third level.

[0051] In one embodiment, if the working condition level is the first level, according to whether the power limit identifier is lifted and the corresponding load shedding mechanism for the working condition level, the offshore connection transformer of the offshore station is shed, including: if after the power limit control is triggered and within the first time threshold corresponding to the first level, the power limit identifier is not lifted, then a pre-selected target offshore connection transformer in the offshore station is shed.

[0052] It can be understood that the first time threshold is set for the first level and is a time parameter used to judge the effectiveness of power limit control. It represents the set time that the system allows the automatic generation control system to attempt to reduce power under this operating condition, and is determined according to the overload state and overload capacity of the onshore transformer at the first level. For example, in the above example, when the onshore transformer is overloaded by 1.45 times at the first level, it can correspond to the 1.5 p.u. / 15 min gear, and the first time threshold can be set to a time less than 15 min, such as 10 min. The target offshore connection transformer is a specific offshore connection transformer selected in advance as the object of disconnection operation among the three offshore connection transformers at the offshore station, based on factors such as equipment performance, operating status, and impact on the system. At the first level, since the overload degree of the remaining onshore connection transformers is relatively light and can withstand a longer time of power limit control attempts, the corresponding first time threshold is the longest. If, within the first time threshold, the automatic generation control system performs power limit control according to the maximum transmissible power and reduces the transmission power below the maximum transmissible power, the power limit flag can be lifted, and there is no need to disconnect the offshore connection transformer at the offshore station, maintaining the current state of the system. However, conversely, if the power limit control attempt fails, load control needs to be carried out in a more direct way, that is, one of the three offshore connection transformers at the offshore station (which can be the No. 3 offshore connection transformer) needs to be disconnected to directly control the overload from the source.

[0053] In one embodiment, please refer to Figure 3 , if the operating condition level is the second level, according to whether the power limit flag is lifted and the disconnection mechanism corresponding to the operating condition level, the offshore connection transformer at the offshore station is disconnected, including steps S302 to S306.

[0054] S302, if after triggering the power limit control, within the second time threshold corresponding to the second level, the power limit flag is not lifted, then disconnect one of the target offshore connection transformers pre-selected at the offshore station.

[0055] It can be understood that the second time threshold is set for the second level and is a time parameter used to judge the effectiveness of power limit control. It represents the set time that the system allows the automatic generation control system to attempt to reduce power under this working condition, and is determined based on the overload state and overload capacity of the onshore transformer at the second level. For example, in the above example, when the onshore transformer is overloaded by 2.3 times at the second level, it can correspond to the gear of 2.3 p.u. / min. Considering the power limit capacity of the offshore wind farm, it can be determined that this tolerance time is longer than the time required to limit the power below the maximum transmissible power. Therefore, the power limit control can be directly attempted. The second time threshold can be set to a time less than 1 minute, such as 45 s. At the second level, due to the heavier overload degree of the remaining onshore connection transformers, they can only withstand a short-time power limit control attempt, and the corresponding second time threshold is shorter than the first time threshold. If, within the second time threshold, the automatic generation control system quickly performs power limit control according to the maximum transmissible power and reduces the transmission power below the maximum transmissible power, the power limit flag can be lifted, and there is no need to disconnect the offshore connection transformer of the offshore substation, maintaining the current state of the system. However, conversely, if the power limit control attempt fails, load control needs to be carried out in a more direct way, that is, one of the three offshore connection transformers, the target offshore connection transformer (which can be the No. 3 offshore connection transformer), needs to be disconnected to directly control the overload from the source.

[0056] S304. After the target offshore connection transformer is disconnected, it is judged whether the power limit flag is still not lifted within the third time threshold corresponding to the second level.

[0057] It can be understood that the third time threshold is another important time parameter set for the working condition level of the second level. It is used to further judge the time interval during which the power limited state of the system is effectively improved after disconnecting one target offshore connection transformer, and can also be formulated according to the overload tolerance capacity of the onshore transformer, such as 50 s. The core principle of this step is that after the target offshore connection transformer is disconnected, the power transmission state of the system will change, but this change may not immediately lift the power limit flag, and it takes a certain time to observe the response and adjustment effect of the system. By setting the third time threshold and continuously monitoring the state of the power limit flag during this time period, it is possible to more accurately judge whether disconnecting one offshore connection transformer is sufficient to relieve the power overload problem of the onshore connection transformer.

[0058] S306. If so, disconnect the offshore connection transformer with the minimum power among the remaining two offshore connection transformers of the offshore substation.

[0059] It can be understood that if the power limit flag is lifted within the third time threshold, it indicates that the disconnection operation is effective, and the current state can be maintained unchanged. Otherwise, it means that disconnecting only one target offshore connection transformer cannot effectively solve the problem of power overload of the onshore connection transformer, and it is necessary to reduce the power output of the offshore station again. The reason for selecting the offshore connection transformer with the smallest power for disconnection is that the loss of the system's power transmission capacity caused by disconnecting this device is relatively small. While alleviating the load of the onshore connection transformer, it can maintain the basic power transmission function of the system to the greatest extent and ensure the power supply requirements of critical loads.

[0060] In one embodiment, when the operating condition level is the third level, when transmitting the maximum transmissible power to the automatic generation control system of the offshore station and setting the power limit flag to trigger power limit control, it further includes: disconnecting a pre-selected target offshore connection transformer in the offshore station.

[0061] It can be understood that in the case of the third level, the overload degree of the last remaining onshore connection transformer is the deepest, close to three times, and the overload tolerance time at this level is only about 2s, which is not enough to attempt power limit control. Therefore, it is necessary to first directly disconnect the target offshore connection transformer to reduce the transmission power before continuing to attempt power limit control.

[0062] In one embodiment, according to whether the power limit flag is lifted and the disconnection mechanism corresponding to the operating condition level, disconnecting the offshore connection transformer of the offshore station includes: after triggering power limit control, determining whether the power limit flag is still not lifted within the fourth time threshold corresponding to the third level. If so, disconnect the offshore connection transformer with the smallest power among the remaining two offshore connection transformers in the offshore station.

[0063] It can be understood that the fourth time threshold is a time parameter specifically set for the third operating condition level. It measures the duration of the system's power-limited state after power-limit control is triggered and serves as an important time basis for determining whether further power removal measures are necessary. At this point, since the target offshore connecting transformer has already been removed, the required power has been initially reduced. The automatic generation control system can attempt to implement power-limit control within the corresponding fourth time threshold. If, within the fourth time threshold, the automatic generation control system implements power-limit control based on the maximum transmittable power and reduces the transmittable power below the maximum transmittable power, the power-limited flag is removed, eliminating the need to remove the offshore connecting transformer at the offshore station and maintaining the current system state. Conversely, if the power-limit control attempt fails, removing only one target offshore connecting transformer will not effectively resolve the power overload problem at the onshore connecting transformer, requiring further reduction of the offshore station's power output. The offshore connecting transformer with the lowest power is selected for removal because removing it reduces the system's power transmission capacity relatively minimally. This minimizes the load on the onshore connecting transformer while maintaining the system's basic power transmission function to the greatest extent possible, ensuring the power supply needs of critical loads.

[0064] In one embodiment, disconnecting a pre-selected offshore transformer at an offshore station involves sequentially triggering the grid-side switch failure protection function, the valve-side switch failure protection function, locking the grid-side switch, and locking the valve-side switch. The grid-side switch failure protection function activates the grid-side switch's failure protection logic before disconnecting the grid-side switch. If the switch fails to operate correctly within a specified time after a trip command, the backup trip circuit is automatically activated to ensure reliable disconnection of the switch. Similarly, the valve-side switch failure protection function provides a protection mechanism for the valve-side switch. Locking the grid-side switch and locking the valve-side switch provide a safety measure to prevent accidental closing of the switch through both electrical and mechanical locking mechanisms after disconnection. The core principle of this operational process is to establish a multi-layered protection system to ensure the reliability and safety of equipment disconnection under extreme operating conditions. At the third operating condition level, the system is already at high risk, and any equipment operation error could result in serious consequences. By sequentially activating the failure protection functions of the grid-side and valve-side switches, a switch failure can be quickly switched to the backup tripping path, preventing the fault from expanding due to switch refusal to operate. The locking operation, after the switch is successfully disconnected, uses multiple locking devices such as electromagnetic locks and mechanical locks to prevent accidental closing of the switch due to external interference or misoperation, ensuring that the equipment remains in a safe and isolated state. This operational process, along with steps such as operating condition level determination and power limit monitoring, forms a complete fault handling chain. Through timing control and logical interlocking, it achieves the safe and reliable disconnection of the offshore transformer.

[0065] This application provides a control device for a HVDC transmission project with sea breeze. The HVDC transmission project with sea breeze includes an offshore station and an onshore station connected to each other. The control device includes:

[0066] A fault response module, configured to determine the maximum transmissible power according to the number of remaining onshore connection transformers and determine the operating condition level according to the overload condition of the onshore connection transformers when receiving a fault signal of the onshore connection transformer.

[0067] A power reduction module, configured to transmit the maximum transmissible power to the automatic generation control system of the offshore station and set a power limit flag to trigger power limit control when the maximum transmissible power is less than the actual power of the current onshore station.

[0068] An excision module, configured to excise the offshore connection transformer of the offshore station according to whether the power limit flag is lifted and the excision mechanism corresponding to the operating condition level.

[0069] For the specific limitations of the control device for the HVDC transmission project with sea breeze, reference can be made to the limitations of the control method for the HVDC transmission project with sea breeze in the above text, which will not be elaborated here. Each module in the above control device and temperature monitoring device for the HVDC transmission project with sea breeze can be implemented in whole or in part through software, hardware, and their combination. The above modules can be embedded in the processor of the computer device in hardware form or independent of it, or stored in the memory of the computer device in software form, so as to facilitate the processor to call and execute the operations corresponding to the above modules. It should be noted that the division of modules in the embodiments of this application is illustrative, only a logical function division, and there may be other division methods in actual implementation.

[0070] This application provides a computer device, including one or more processors and a memory. Computer-readable instructions are stored in the memory. When the computer-readable instructions are executed by one or more processors, the steps of the control method for the HVDC transmission project with sea breeze in any of the above embodiments are executed.

[0071] This application provides a storage medium, in which computer-readable instructions are stored. When the computer-readable instructions are executed by one or more processors, one or more processors are caused to execute the steps of the control method for the HVDC transmission project with sea breeze in any of the above embodiments.

[0072] Schematically, as Figure 4 shown, Figure 4 is a schematic internal structure diagram of a computer device provided by an embodiment of this application. Refer to Figure 4Computer device 400 includes a processing component 402, which further includes one or more processors, and memory resources represented by memory 401 for storing instructions executable by processing component 402, such as application programs. The application programs stored in memory 401 may include one or more modules, each corresponding to a set of instructions. Furthermore, processing component 402 is configured to execute instructions to perform the steps of the control method for an offshore wind flexible direct current transmission project or the temperature monitoring method for a dry-type reactor in any of the aforementioned embodiments.

[0073] The computer device 400 may further include a power supply component 403 configured to perform power management of the computer device 400 , a wired or wireless network interface 404 configured to connect the computer device 400 to a network, and an input / output (I / O) interface 405 .

[0074] In one embodiment, when the computer-readable instructions are executed by one or more processors, the steps of the control method of the offshore wind flexible direct current transmission project in any of the above embodiments are executed.

[0075] Those skilled in the art will understand that Figure 4 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0076] In one embodiment, when the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the control method of the offshore wind flexible direct current transmission project in any of the above embodiments.

[0077] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referenced to each other.

[0078] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a sea breeze HVDC transmission project, characterized in that, The described HVDC light transmission project for sea breeze includes a sea station and a land station that are interconnected. The control method includes: In the case of receiving a fault signal of the onshore connection transformer, determining the maximum transmissible power according to the number of remaining onshore connection transformers, and determining the operating condition level according to the overload condition of the remaining onshore connection transformers; If the maximum transmissible power is less than the actual power of the current land station, then transmit the maximum transmissible power to the automatic generation control system of the sea station and set a power limit flag to trigger the automatic generation control system to perform power limit control; According to whether the power limit flag is lifted and the disconnection mechanism corresponding to the operating condition level, disconnect the offshore connection transformer of the sea station.

2. The control method of the HVDC transmission project with gentle sea breeze according to claim 1, wherein The determining the operating condition level according to the overload condition of the remaining onshore connection transformers includes: If the number of onshore connection transformers changes from three to two and the overload condition exceeds a first threshold, then determine the operating condition level as the first level; If the number of onshore connection transformers changes from two to one and the overload condition exceeds a second threshold, then determine the operating condition level as the second level; the second threshold is greater than the first threshold; If the number of onshore connection transformers changes from three to one and the overload condition exceeds a third threshold, then determine the operating condition level as the third level; the third threshold is greater than the second threshold.

3. The control method of the HVDC transmission project with gentle sea breeze according to claim 2, wherein, If the operating condition level is the first level, the disconnecting the offshore connection transformer of the sea station according to whether the power limit flag is lifted and the disconnection mechanism corresponding to the operating condition level includes: If after triggering the power limit control, within the first time threshold corresponding to the first level, the power limit flag is not lifted, then disconnect one pre-selected target offshore connection transformer in the sea station.

4. The control method of the HVDC transmission project with gentle sea breeze according to claim 2, characterized in that, If the operating condition level is the second level, the disconnecting the offshore connection transformer of the sea station according to whether the power limit flag is lifted and the disconnection mechanism corresponding to the operating condition level includes: If after triggering the power limit control, within the second time threshold corresponding to the second level, the power limit flag is not lifted, then disconnect one pre-selected target offshore connection transformer in the sea station; After the target offshore connection transformer is disconnected, determine whether the power limit flag is still not lifted within the third time threshold corresponding to the second level; If so, then disconnect the one with the minimum power among the remaining two offshore connection transformers in the sea station.

5. The control method of the HVDC transmission project with gentle sea breeze according to claim 2, characterized in that, If the operating condition level is the third level, when transmitting the maximum transmissible power to the automatic generation control system of the sea station and setting a power limit flag to trigger power limit control, it further includes: Disconnect one pre-selected target offshore connection transformer in the sea station.

6. The control method of the HVDC transmission project with gentle sea breeze according to claim 5, characterized in that, The disconnecting the offshore connection transformer of the sea station according to whether the power limit flag is lifted and the disconnection mechanism corresponding to the operating condition level includes: After triggering the power limit control, determine whether the power limit flag is still not lifted within the fourth time threshold corresponding to the third level; If so, cut off the one with the minimum power among the remaining two offshore connection transformers of the offshore substation.

7. The control method of the HVDC transmission project for sea breeze according to any one of claims 3-6, characterized in that, The target offshore connection transformer includes a grid-side switch and a valve-side switch. Cutting off a pre-selected target offshore connection transformer in the offshore substation includes: Sequentially perform the following actions: Trigger the malfunction function of the grid-side switch, trigger the malfunction function of the valve-side switch, lock the grid-side switch, and lock the valve-side switch.

8. A control device for a HVDC transmission project with sea breeze, characterized in that, The HVDC light transmission project for sea breeze includes an interconnected offshore substation and onshore substation. The control device includes: A fault response module, configured to, when receiving an onshore connection transformer fault signal, determine the maximum transmissible power according to the number of remaining onshore connection transformers, and determine the operating condition level according to the overload condition of the remaining onshore connection transformers; A power reduction module, configured to, when the maximum transmissible power is less than the actual power of the current onshore substation, transmit the maximum transmissible power to the automatic generation control system of the offshore substation and set a power limit flag to trigger power limit control; A cut-off module, configured to cut off the offshore connection transformers of the offshore substation according to whether the power limit flag is lifted and the cut-off mechanism corresponding to the operating condition level.

9. A computer device, characterized in that, It includes one or more processors and a memory. Computer-readable instructions are stored in the memory. When the computer-readable instructions are executed by the one or more processors, the steps of the control method of the HVDC light transmission project for sea breeze according to any one of claims 1-7 are executed.

10. A storage medium, characterized in that, Computer-readable instructions are stored in the storage medium. When the computer-readable instructions are executed by one or more processors, the one or more processors are caused to execute the steps of the control method of the HVDC light transmission project for sea breeze according to any one of claims 1-7.

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