Multi-receiving-end voltage cooperative control method and device of offshore wind power flexible direct current sending-out system, electronic equipment and storage medium

Abstract

The invention discloses a multi-receiving-end voltage cooperative control method and device of an offshore wind power flexible direct current sending-out system, electronic equipment and a storage medium, and belongs to the field of power system control, and the method comprises the steps: obtaining a voltage value of an offshore wind turbine alternating current collection bus in real time according to a preset control period; after each time of acquisition, voltage coordinated regulation and control operation is executed; the voltage coordinated regulation and control operation comprises the steps of obtaining a real-time AC line power value of each receiving end converter station; determining a direct-current voltage regulation reference value according to the real-time voltage value and an alternating-current voltage upper limit threshold value; according to the real-time AC line power value, the power reference value, the droop coefficient and the reference value of each receiving end converter station, calculating and generating a corresponding DC voltage reference value; and each receiving-end converter station is controlled to operate according to the respective direct-current voltage reference value. Therefore, by implementing the invention, the problem that the overvoltage risk of the sending end cannot be effectively suppressed by using a voltage coupling mechanism due to the stiffness of the reference value in the prior art can be solved.

Description

Technical Field

[0001] This invention relates to the field of power system control technology, specifically to a method, device, electronic equipment, and storage medium for multi-receiving-end voltage coordinated control of an offshore wind power flexible DC transmission system. Background Technology

[0002] As offshore wind power expands to deeper waters and on a larger scale, flexible DC transmission has become the main technology for grid connection of offshore wind power due to its advantages such as long transmission distance and strong controllability. To address the issue of absorbing large-scale offshore wind power, a multi-receiving-end grid connection structure is often adopted, which transmits electricity to multiple different regional power grids on land via DC transmission systems. In a multi-receiving-end system, each receiving-end converter station not only undertakes the task of receiving electricity but also must maintain the stability of the DC voltage and rationally allocate active power through coordinated control. This is crucial for ensuring the safe and stable operation of the entire offshore wind power transmission system.

[0003] However, existing multi-receiving-end flexible DC transmission systems still have limitations in terms of coordinated control. Currently, receiving-end converter stations typically employ control strategies based on DC voltage droop characteristics, with the core parameter, the DC voltage regulation reference value, usually set as a fixed constant. In offshore wind power transmission systems, there is often a direct voltage coupling mapping relationship between the AC voltage at the sending end (offshore) and the DC voltage of the DC transmission system. Existing control methods ignore this coupling characteristic. When the AC collector bus voltage of the offshore wind turbine rises abnormally due to changes in operating conditions, the receiving-end converter station rigidly maintains a fixed DC voltage reference, making it impossible to utilize the aforementioned coupling relationship to adjust the DC side voltage to counteract and alleviate the voltage pressure on the sending-end AC side. This poses a potential safety hazard to the equipment of the offshore wind power system. Summary of the Invention

[0004] This invention provides a method, device, electronic equipment, and storage medium for coordinated control of multi-receiving-end voltage in a flexible DC transmission system for offshore wind power. It can solve the problem in the prior art that the voltage coupling mechanism cannot effectively suppress the risk of overvoltage at the sending end due to the rigidity of the reference value.

[0005] One embodiment of the present invention provides a multi-receiving-end voltage coordinated control method for an offshore wind power flexible DC transmission system. The offshore wind power flexible DC transmission system includes: an AC collecting bus for offshore wind turbines at the sending end and at least two receiving-end converter stations at the receiving end. The multi-receiving-end voltage collaborative control method includes: According to the preset control cycle, the real-time voltage value of the AC collection bus of the offshore wind turbine is acquired in real time. After acquiring each of the aforementioned real-time voltage values, a voltage coordination control operation is performed; The voltage coordinated regulation operation includes: Obtain the real-time AC line power values ​​of the at least two receiving-end converter stations; Based on the real-time voltage value and the preset AC voltage upper limit threshold, the current DC voltage regulation reference value is determined; Based on the real-time AC line power value, the AC line power reference value preset for each receiving-end converter station, the droop coefficient preset for each receiving-end converter station, and the current DC voltage regulation reference value, the current DC voltage reference value of each receiving-end converter station is calculated and generated. Based on the current DC voltage reference value of each receiving-end converter station, control each receiving-end converter station to maintain its operation at its current DC voltage reference value.

[0006] Furthermore, determining the current DC voltage regulation reference value based on the real-time voltage value and the preset AC voltage upper limit threshold includes: Determine whether the real-time voltage value is greater than the AC voltage upper limit threshold; If the real-time voltage value is not greater than the upper limit threshold of the AC voltage, then the preset DC voltage rating of the offshore wind power flexible DC transmission system is determined as the current DC voltage regulation reference value. If the real-time voltage value is greater than the upper limit threshold of the AC voltage, then the DC voltage regulation reference value of the previous control cycle is decremented, and the decremented value is determined as the current DC voltage regulation reference value.

[0007] Furthermore, the step of performing a numerical decrementing process on the DC voltage regulation reference value of the previous control cycle includes: Calculate the difference between the DC voltage regulation reference value of the previous control cycle and the preset step size value; Determine whether the difference is less than a preset DC voltage lower limit threshold; If the difference is not less than the DC voltage lower limit threshold, then the difference is determined as the current DC voltage regulation reference value; If the difference is less than the DC voltage lower limit threshold, then the DC voltage lower limit threshold is determined as the current DC voltage regulation reference value.

[0008] Furthermore, the step of calculating and generating the current DC voltage reference value for each receiving-end converter station based on the real-time AC line power value, the preset AC line power reference value for each receiving-end converter station, the preset droop coefficient for each receiving-end converter station, and the current DC voltage regulation reference value includes: For each receiving-end converter station, calculate the difference between the current real-time AC line power value of the receiving-end converter station and the preset AC line power reference value for the current receiving-end converter station, and generate a power deviation value. The power deviation value is weighted using a droop coefficient preset for the current receiving-end converter station to obtain the voltage correction amount; The voltage correction is superimposed on the current DC voltage regulation reference value to obtain the current DC voltage reference value of the receiving-end converter station.

[0009] Furthermore, the calculation of the current DC voltage reference value for each receiving-end converter station is specifically obtained through the following formula: In the formula, For the first The current DC voltage reference value of the receiving-end converter station For the first Real-time AC line power values ​​of each receiving-end converter station For the first The preset AC line power reference value for each receiving-end converter station For the first The preset droop coefficient for each receiving-end converter station This is the current DC voltage regulation reference value.

[0010] Furthermore, the preset AC line power reference value for each receiving-end converter station is generated in the following manner: Obtain the total rated power of all receiving-end converter stations and the preset power allocation ratio among each receiving-end converter station; According to the preset power allocation ratio, the total rated power is allocated to each receiving-end converter station to obtain the AC line power reference value for each receiving-end converter station.

[0011] Furthermore, the preset droop coefficient for each receiving-end converter station is generated in the following manner: Obtain the maximum and minimum values ​​of the total wind power injected into the offshore wind power flexible DC transmission system; Based on the maximum value of the total wind power, the minimum value of the total wind power, and the total rated power of all receiving-end converter stations, and based on the allowable deviation range of DC voltage during steady-state operation of the system, constraints on the droop coefficient of all receiving-end converter stations are constructed. The value that satisfies the aforementioned constraint is selected as the preset droop coefficient for each receiving-end converter station. The constraints are specifically as follows: In the formula, For the first The preset droop coefficient for each receiving-end converter station This represents the total number of receiving-end converter stations. This represents the maximum value of the total wind power. This represents the minimum total wind power output. The total rated power of all receiving-end converter stations. This refers to the preset DC voltage rating of the offshore wind power flexible DC transmission system. This is the preset allowable deviation coefficient for DC voltage.

[0012] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments.

[0013] One embodiment of the present invention provides a multi-receiving-end voltage coordinated control device for a flexible DC transmission system for offshore wind power. The flexible DC transmission system for offshore wind power includes: an AC collecting bus of offshore wind turbines at the sending end and at least two receiving-end converter stations at the receiving end. The multi-terminal voltage coordinated control device includes: a bus voltage value acquisition module, a regulation triggering module, and a voltage coordinated regulation module; The bus voltage value acquisition module is used to acquire the real-time voltage value of the AC collection bus of the offshore wind turbine in real time according to a preset control cycle. The control triggering module is used to call the voltage collaborative control module after each real-time voltage value is acquired; The voltage coordination control module is used to acquire the real-time AC line power values ​​of the at least two receiving-end converter stations; determine the current DC voltage control reference value based on the real-time voltage value and a preset AC voltage upper limit threshold; calculate and generate the current DC voltage reference value for each receiving-end converter station based on the real-time AC line power value, a preset AC line power reference value for each receiving-end converter station, a preset droop coefficient for each receiving-end converter station, and the current DC voltage control reference value; and control each receiving-end converter station to operate at its current DC voltage reference value based on the current DC voltage reference value of each receiving-end converter station.

[0014] Based on the above method embodiments, the present invention provides corresponding electronic device embodiments.

[0015] An embodiment of the present invention provides an electronic device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the multi-receiving-end voltage coordinated control method of the offshore wind power flexible DC transmission system described in any of the above-described method embodiments.

[0016] Based on the above method embodiments, the present invention provides corresponding storage medium embodiments.

[0017] One embodiment of the present invention provides a storage medium storing a computer program, wherein, when the computer program is running, it controls the device where the storage medium is located to execute the multi-receiving-end voltage coordinated control method of the offshore wind power flexible DC transmission system described in any of the above-described method embodiments.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method, apparatus, electronic device, and storage medium for multi-receiving-end voltage coordinated control of an offshore wind power flexible DC transmission system. The method acquires the voltage value of the AC collecting bus of the offshore wind turbine in real time according to a preset control cycle; after each acquisition, a voltage coordinated control operation is performed; the voltage coordinated control operation includes: acquiring the real-time AC line power value of each receiving-end converter station; determining a DC voltage control reference value based on the real-time voltage value and the AC voltage upper limit threshold; calculating and generating a corresponding DC voltage reference value based on the real-time AC line power value, power reference value, droop coefficient, and the reference value of each receiving-end converter station; and controlling each receiving-end converter station to operate according to its respective DC voltage reference value, thereby achieving voltage coordination and power balance among multiple receiving ends.

[0019] This invention acquires the real-time voltage value of the AC collector bus of an offshore wind turbine and dynamically determines the current DC voltage regulation reference value based on a comparison between this real-time voltage value and a preset upper limit threshold. Utilizing the coupling mapping characteristic between the AC voltage at the sending end and the DC transmission voltage in the offshore wind power transmission system, this invention reduces the DC side voltage by lowering the DC voltage regulation reference value at the receiving end when an overvoltage risk occurs at the sending end. This, in turn, forces the voltage of the AC collector bus of the offshore wind turbine at the sending end to decrease accordingly. This overcomes the technical deficiency of existing technologies where the rigid reference value prevents the effective suppression of overvoltage risks at the sending end using a voltage coupling mechanism. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a multi-receiving-end voltage collaborative control method for a flexible DC transmission system for offshore wind power, provided in an embodiment of the present invention.

[0021] Figure 2 This is a schematic flowchart of a voltage coordinated regulation operation provided in an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the structure of a multi-receiving-end voltage collaborative control device for a flexible DC transmission system for offshore wind power, provided in an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, in order to solve the problem that the voltage coupling mechanism cannot effectively suppress the risk of overvoltage at the sending end due to the rigidity of the reference value in the prior art, an embodiment of the present invention provides a multi-receiving end voltage collaborative control method for a flexible DC transmission system for offshore wind power. The flexible DC transmission system for offshore wind power includes: an AC collection bus of offshore wind turbines at the sending end and at least two receiving end converter stations at the receiving end. Specifically, the architecture of the offshore wind power flexible DC transmission system upon which this method is based is first described. This system includes an AC collecting bus at the sending end of the offshore wind turbines and at least two receiving-end converter stations. The AC collecting bus at the sending end collects the AC power generated by the offshore wind farm and connects it to the DC transmission line via a rectifier. In practice, the rectifier typically uses a diode rectifier. Due to the uncontrollable nature of diode rectifiers, an inherent AC / DC voltage mapping coupling relationship exists between the offshore AC voltage and the DC voltage of the DC transmission system. This is the physical basis for this invention's ability to suppress the sending-end AC voltage by adjusting the DC-side voltage. The at least two receiving-end converter stations (which can be labeled converter station 1 to converter station n, where n is an integer greater than or equal to 2) are connected to the end of the DC transmission line to invert the DC power and transmit it to their respective connected onshore AC regional power grids.

[0025] The multi-receiving-end voltage coordinated control method includes at least the following steps: Step S1: According to the preset control cycle, obtain the real-time voltage value of the AC collection bus of the offshore wind turbine. Specifically, the preset control cycle here is the time step for the digital control system to perform logical operations. At the beginning of this cycle, the voltage of the AC busbar of the offshore wind turbine is sampled by voltage transformers and measurement and control devices installed on the offshore sending-end platform to obtain a real-time voltage value that reflects the current voltage safety status of the sending end. Simultaneously, to achieve coordinated power distribution among multiple receiving ends, the system also needs to synchronously acquire the actual AC line power values ​​of at least two receiving-end converter stations within the same control cycle. Through the real-time synchronous acquisition of the aforementioned sending-end voltage data and receiving-end power data, accurate and timely data support is provided for the subsequent control system to determine whether there is an overvoltage risk and to calculate the coordinated control commands for each converter station, ensuring that the control system can comprehensively perceive the safety margin of the sending end and the operating conditions of the receiving end.

[0026] Step S2: After acquiring each of the aforementioned real-time voltage values, perform voltage coordinated regulation operation; Specifically, after acquiring each real-time voltage value, executing voltage coordinated regulation is a key step in connecting state perception and control execution in this embodiment. This operation is typically implemented using the centralized control system of the offshore wind power flexible DC transmission system or a control center with global coordination capabilities. Its execution logic is designed as a real-time response task strictly synchronized with the sampling process. Specifically, once the real-time voltage value of the offshore wind turbine AC collection bus is updated within the current control cycle, the system immediately triggers and enters the logic flow of the voltage coordinated regulation operation without waiting for other external instructions. This data-driven triggering mechanism ensures that the operation cycle of the control system is consistent with the electrical quantity change cycle of the offshore wind farm, enabling timely detection of small voltage fluctuations at the sending end caused by sudden changes in offshore wind power or load disturbances at the receiving end. It also provides immediate computing power support and process guidance for determining the DC voltage regulation reference value and calculating the coordinated control instructions for each converter station in subsequent steps, thereby ensuring that the entire multi-terminal system can respond to the voltage stabilization requirements of the offshore sending end with minimal control delay.

[0027] like Figure 2 As shown, in a preferred embodiment, the voltage coordinated regulation operation includes: S2.1 Obtain the real-time AC line power values ​​of the at least two receiving-end converter stations; Specifically, this step aims to monitor the actual power absorption of the multi-terminal flexible DC transmission system at the receiving end in real time, providing feedback for subsequent power coordination and allocation. Specifically, for offshore wind power flexible DC transmission systems containing multiple receiving-end converter stations, the control system uses power measurement devices installed on the AC side of each converter station to collect in real time the active power injected by each receiving-end converter station into the onshore AC grid it connects to, and uses this active power value as the corresponding real-time AC line power value for that receiving-end converter station. This real-time data directly reflects the current actual operating conditions of each receiving-end converter station. Under an ideal DC grid model that ignores DC line resistance, the power status of these receiving-end converter stations distributed in different geographical locations collectively determines the dynamic balance of the DC voltage. By accurately acquiring the real-time AC line power value of each receiving-end converter station, the control system can ensure accurate closed-loop feedback data when performing subsequent droop control calculations, thereby ensuring that each converter station can accurately adjust the DC-side voltage according to its actual power level, achieving on-demand coordinated absorption of offshore wind power.

[0028] S2.2 Determine the current DC voltage regulation reference value based on the real-time voltage value and the preset AC voltage upper limit threshold. In a preferred embodiment, determining the current DC voltage regulation reference value based on the real-time voltage value and a preset AC voltage upper limit threshold includes: Determine whether the real-time voltage value is greater than the AC voltage upper limit threshold; If the real-time voltage value is not greater than the upper limit threshold of the AC voltage, then the preset DC voltage rating of the offshore wind power flexible DC transmission system is determined as the current DC voltage regulation reference value. If the real-time voltage value is greater than the upper limit threshold of the AC voltage, then the DC voltage regulation reference value of the previous control cycle is decremented, and the decremented value is determined as the current DC voltage regulation reference value.

[0029] In a preferred embodiment, the step of performing a numerical decrementing process on the DC voltage regulation reference value of the previous control cycle includes: Calculate the difference between the DC voltage regulation reference value of the previous control cycle and the preset step size value; Determine whether the difference is less than a preset DC voltage lower limit threshold; If the difference is not less than the DC voltage lower limit threshold, then the difference is determined as the current DC voltage regulation reference value; If the difference is less than the DC voltage lower limit threshold, then the DC voltage lower limit threshold is determined as the current DC voltage regulation reference value.

[0030] In a preferred embodiment, the step of calculating and generating the current DC voltage reference value for each receiving-end converter station based on the real-time AC line power value, the preset AC line power reference value for each receiving-end converter station, the preset droop coefficient for each receiving-end converter station, and the current DC voltage regulation reference value includes: For each receiving-end converter station, calculate the difference between the current real-time AC line power value of the receiving-end converter station and the preset AC line power reference value for the current receiving-end converter station, and generate a power deviation value. The power deviation value is weighted using a droop coefficient preset for the current receiving-end converter station to obtain the voltage correction amount; The voltage correction is superimposed on the current DC voltage regulation reference value to obtain the current DC voltage reference value of the receiving-end converter station.

[0031] In a preferred embodiment, the calculation of the current DC voltage reference value for each receiving-end converter station is specifically obtained through the following formula: In the formula, For the first The current DC voltage reference value of the receiving-end converter station For the first Real-time AC line power values ​​of each receiving-end converter station For the first The preset AC line power reference value for each receiving-end converter station For the first The preset droop coefficient for each receiving-end converter station This is the current DC voltage regulation reference value.

[0032] Specifically, the voltage coordinated regulation operation further includes: determining the current DC voltage regulation reference value based on the real-time voltage value and a preset AC voltage upper limit threshold. This step is a core component of connection status perception and control decision-making, aiming to dynamically adjust the voltage operation level of the entire DC transmission system according to the voltage safety status of the sending-end system.

[0033] In one embodiment, the process of determining the current DC voltage regulation reference value specifically includes: the system first determines whether the real-time voltage value is greater than the AC voltage upper limit threshold (e.g., 1.1 pu as set by the standard). If the determination result is no, that is, the real-time voltage value is not greater than the AC voltage upper limit threshold, it indicates that the offshore transmission system is within the normal operating voltage range and no additional overvoltage suppression is required. In order to ensure the system transmission efficiency and steady-state performance, the system directly determines the preset DC voltage rating of the offshore wind power flexible DC transmission system as the current DC voltage regulation reference value, so that the system maintains operation at the rated voltage level. If the determination result is yes, that is, the real-time voltage value is greater than the AC voltage upper limit threshold, it indicates that there is an overvoltage risk at the transmission end. At this time, the system starts the voltage suppression logic, does not reset the reference value, but performs a numerical decrement process based on the DC voltage regulation reference value of the previous control cycle, and determines the decremented value as the current DC voltage regulation reference value, thereby pulling the system voltage down by reducing the DC voltage reference.

[0034] In one embodiment, to ensure the smoothness of the voltage regulation process and prevent DC voltage collapse due to excessive regulation, the specific logic for performing numerical decrement processing on the DC voltage regulation reference value of the previous control cycle is as follows: The system calculates the difference between the DC voltage regulation reference value of the previous control cycle and a preset step size value, which determines the voltage regulation ramp-down rate. Then, this difference is compared with a preset DC voltage lower limit threshold (e.g., 0.9 pu). If the difference is not less than the DC voltage lower limit threshold, it indicates that the current regulation amount is still within the system's safe allowable range, and the difference is directly determined as the current DC voltage regulation reference value. If the difference is less than the DC voltage lower limit threshold, it indicates that the regulation has reached the safety threshold. To protect the safety of the converter valve and related equipment, the system forcibly determines the DC voltage lower limit threshold as the current DC voltage regulation reference value and no longer reduces it.

[0035] After determining a unified DC voltage regulation reference value for the entire system, the voltage coordinated regulation operation further includes: calculating and generating the current DC voltage reference value for each receiving-end converter station based on the real-time AC line power value, the preset AC line power reference value for each receiving-end converter station, the preset droop coefficient for each receiving-end converter station, and the current DC voltage regulation reference value. This step achieves differentiated power allocation under a unified reference. Specifically, for each receiving-end converter station, the system first calculates the difference between the current real-time AC line power value of the receiving-end converter station and the preset AC line power reference value for the current receiving-end converter station. This difference reflects the current power imbalance of the converter station, thereby generating a power deviation value. Next, the power deviation value is weighted using the preset droop coefficient for the current receiving-end converter station, that is, the deviation value is multiplied by the coefficient to obtain the voltage correction amount required by the station to share the power imbalance. Finally, the voltage correction amount is superimposed on the current DC voltage regulation reference value to obtain the current DC voltage reference value of the receiving-end converter station, which serves as the underlying voltage tracking command.

[0036] Furthermore, the formula for calculating the current DC voltage reference value of each receiving-end converter station clarifies how, in a multi-terminal DC system, each receiving-end converter station adjusts its DC terminal voltage based on a unified dynamic reference value, according to its own droop characteristics and power settings. This achieves on-demand power allocation across multiple terminals while utilizing the AC / DC voltage coupling characteristics of diode rectifiers to effectively suppress the AC collection bus voltage of the sending-end offshore wind turbine by shifting the overall DC voltage of the receiving end. This solves the technical problem in the prior art where rigid control references prevent the simultaneous consideration of power coordination and sending-end overvoltage protection.

[0037] S2.3. Based on the real-time AC line power value, the AC line power reference value preset for each receiving-end converter station, the droop coefficient preset for each receiving-end converter station, and the current DC voltage regulation reference value, calculate and generate the current DC voltage reference value for each receiving-end converter station. In a preferred embodiment, a preset AC line power reference value for each receiving-end converter station is generated in the following manner: Obtain the total rated power of all receiving-end converter stations and the preset power allocation ratio among each receiving-end converter station; According to the preset power allocation ratio, the total rated power is allocated to each receiving-end converter station to obtain the AC line power reference value for each receiving-end converter station.

[0038] In a preferred embodiment, the preset droop coefficient for each receiving-end converter station is generated in the following manner: Obtain the maximum and minimum values ​​of the total wind power injected into the offshore wind power flexible DC transmission system; Based on the maximum value of the total wind power, the minimum value of the total wind power, and the total rated power of all receiving-end converter stations, and based on the allowable deviation range of DC voltage during steady-state operation of the system, constraints on the droop coefficient of all receiving-end converter stations are constructed. The value that satisfies the aforementioned constraint is selected as the preset droop coefficient for each receiving-end converter station. The constraints are specifically as follows: In the formula, For the first The preset droop coefficient for each receiving-end converter station This represents the total number of receiving-end converter stations. This represents the maximum value of the total wind power. This represents the minimum total wind power output. The total rated power of all receiving-end converter stations. This refers to the preset DC voltage rating of the offshore wind power flexible DC transmission system. This is the preset allowable deviation coefficient for DC voltage.

[0039] Specifically, to achieve coordinated absorption and precise control of offshore wind power by each receiving-end converter station, the voltage coordinated regulation operation further includes: calculating and generating the current DC voltage reference value for each receiving-end converter station based on the real-time AC line power value, the preset AC line power reference value for each receiving-end converter station, the preset droop coefficient for each receiving-end converter station, and the current DC voltage regulation benchmark value. This step is the specific execution link of the droop control strategy. Among them, the "preset AC line power reference value" and the "preset droop coefficient" are key static parameters that determine the power distribution characteristics and system voltage stability, and their generation method is directly related to the steady-state performance and dynamic boundary of the system.

[0040] In one embodiment, to ensure that each receiving-end converter station can share the offshore wind power according to the planned ratio, a preset AC line power reference value for each receiving-end converter station is generated as follows: First, the total rated power of all receiving-end converter stations (i.e., the sum of the design capacity or planned absorption capacity of all receiving-end converter stations) and the preset power allocation ratio among each receiving-end converter station are obtained. This preset power allocation ratio is usually preset based on the absorption capacity of each receiving-end grid, the converter station capacity ratio, or dispatch instructions (e.g., 2:1 or 1:1, etc.). Subsequently, according to the preset power allocation ratio, the total rated power is allocated to each receiving-end converter station, and the calculated value is the AC line power reference value for each receiving-end converter station. Through this parameter tuning based on total capacity and allocation ratio, when the system DC voltage is at its rated state, the power output of each converter station can strictly follow the preset proportional relationship, realizing the orderly guidance of power flow.

[0041] In one embodiment, to ensure that the DC voltage deviation of the system remains within a safe range during wind power fluctuations, a preset droop coefficient for each receiving-end converter station is generated as follows: First, the system obtains the maximum and minimum total wind power injected into the offshore wind power flexible DC transmission system. These two values ​​define the extreme power fluctuations the system may withstand. Then, based on the maximum and minimum total wind power, and the total rated power of all receiving-end converter stations determined in the preceding steps, and combined with the allowable DC voltage deviation range during steady-state operation of the system (e.g., the rated voltage of the rated voltage), a droop coefficient is generated. By utilizing the electrical characteristic that DC voltage deviation is proportional to unbalanced power, constraints are constructed for the droop coefficient of all receiving-end converter stations. Finally, within the numerical range that satisfies these constraints, specific values ​​are selected as the preset droop coefficient for each receiving-end converter station. This constraint design ensures that regardless of fluctuations in wind power between its maximum and minimum values, the resulting steady-state DC voltage deviation will not exceed the system's set allowable range, thus effectively guaranteeing the voltage stability of the DC grid while achieving coordinated power absorption.

[0042] S2.4. Based on the current DC voltage reference value of each receiving-end converter station, control each receiving-end converter station to maintain its current DC voltage reference value.

[0043] Specifically, after calculating the DC voltage reference value for each receiving-end converter station, this value is sent as the final voltage control command to the local controller of each receiving-end converter station. Based on this command, the receiving-end converter stations adjust the modulation strategy and on / off state of their internal power electronic switching devices to forcibly stabilize the actual operating voltage on the DC side of each receiving-end converter station at the level set by the DC voltage reference value. Since this DC voltage reference value is calculated based on the real-time power feedback of each converter station and a unified and dynamically adjusted DC voltage regulation benchmark value, when all receiving-end converter stations are tracking this reference value, the system can, at the physical level, not only automatically and precisely distribute active power among different receiving-end converter stations according to a preset ratio determined by a preset AC line power reference value and a preset droop coefficient, but also physically reduce the DC side voltage of the receiving-end converter stations by responding to the reduced reference value when an overvoltage risk occurs at the sending end, causing a decrease in the DC voltage regulation benchmark value. This reduction in receiving-end voltage is transmitted to the sending end via the DC transmission line. Utilizing the inherent AC / DC voltage coupling mapping characteristics of the sending-end diode rectifier, the voltage of the sending-end offshore wind turbine AC collector bus is reverse-clamped, forcing it to decrease accordingly. By implementing this step, the calculation results at the control level can be translated into voltage regulation actions at the physical level. This achieves coordinated absorption of offshore wind power by multiple receiving ends while effectively suppressing the risk of overvoltage at the sending end through the AC / DC coupling mechanism.

[0044] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments.

[0045] like Figure 3 As shown, an embodiment of the present invention provides a multi-receiving-end voltage collaborative control device for an offshore wind power flexible DC transmission system. The offshore wind power flexible DC transmission system includes: an offshore wind turbine AC collecting bus at the sending end and at least two receiving-end converter stations at the receiving end. The multi-terminal voltage coordinated control device includes: a bus voltage value acquisition module, a regulation triggering module, and a voltage coordinated regulation module; The bus voltage value acquisition module is used to acquire the real-time voltage value of the AC collection bus of the offshore wind turbine in real time according to a preset control cycle. The control triggering module is used to call the voltage collaborative control module after each real-time voltage value is acquired; The voltage coordination control module is used to acquire the real-time AC line power values ​​of the at least two receiving-end converter stations; determine the current DC voltage control reference value based on the real-time voltage value and a preset AC voltage upper limit threshold; calculate and generate the current DC voltage reference value for each receiving-end converter station based on the real-time AC line power value, a preset AC line power reference value for each receiving-end converter station, a preset droop coefficient for each receiving-end converter station, and the current DC voltage control reference value; and control each receiving-end converter station to operate at its current DC voltage reference value based on the current DC voltage reference value of each receiving-end converter station.

[0046] It should be noted that the embodiments of the device described above correspond to the embodiments of the present invention described above, and can realize the multi-receiving-end voltage coordinated control method of the offshore wind power flexible DC transmission system described above. Furthermore, the embodiments of the device described above are merely illustrative. The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. In addition, in the accompanying drawings of the device embodiments provided by the present invention, the connection relationship between modules indicates that they have a communication connection, which can be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without creative effort.

[0047] Based on the above-described method embodiments of the present invention, a corresponding embodiment of an electronic device is provided.

[0048] An embodiment of the present invention provides an electronic device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the multi-receiving-end voltage coordinated control method of the offshore wind power flexible DC transmission system according to any one of the present invention, or, when the processor executes the computer program, it implements the functions of each module in the above-described device embodiments.

[0049] For example, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in the terminal device.

[0050] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0051] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0052] The memory can be used to store the computer programs and / or modules. The processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and by calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, applications required for at least one function, etc.; the data storage area may store data created based on the use of the mobile phone, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital card (SD card), flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0053] Based on the above method embodiments, the present invention provides corresponding storage medium embodiments; Another embodiment of the present invention provides a storage medium including a stored computer program, wherein, when the computer program is running, the device where the storage medium is located controls the execution of the multi-receiving-end voltage coordinated control method of any of the above-described offshore wind power flexible DC transmission systems of the present invention.

[0054] The aforementioned storage medium is a computer-readable storage medium, and the computer program includes computer program code, which may be in the form of source code, object code, executable file, or certain intermediate forms. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0055] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0056] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for coordinated control of multi-receiving-end voltages in an offshore wind power flexible DC transmission system, characterized in that, The offshore wind power flexible DC transmission system includes: an AC collecting bus of offshore wind turbines at the sending end and at least two receiving-end converter stations at the receiving end. The multi-receiving-end voltage collaborative control method includes: According to the preset control cycle, the real-time voltage value of the AC collection bus of the offshore wind turbine is acquired in real time. After acquiring each of the aforementioned real-time voltage values, a voltage coordination control operation is performed; The voltage coordinated regulation operation includes: Obtain the real-time AC line power values ​​of the at least two receiving-end converter stations; Based on the real-time voltage value and the preset AC voltage upper limit threshold, the current DC voltage regulation reference value is determined; Based on the real-time AC line power value, the AC line power reference value preset for each receiving-end converter station, the droop coefficient preset for each receiving-end converter station, and the current DC voltage regulation reference value, the current DC voltage reference value of each receiving-end converter station is calculated and generated. Based on the current DC voltage reference value of each receiving-end converter station, control each receiving-end converter station to maintain its operation at its current DC voltage reference value.

2. The multi-receiving-end voltage coordinated control method for offshore wind power flexible DC transmission system as described in claim 1, characterized in that, The step of determining the current DC voltage regulation reference value based on the real-time voltage value and the preset AC voltage upper limit threshold includes: Determine whether the real-time voltage value is greater than the AC voltage upper limit threshold; If the real-time voltage value is not greater than the upper limit threshold of the AC voltage, then the preset DC voltage rating of the offshore wind power flexible DC transmission system is determined as the current DC voltage regulation reference value. If the real-time voltage value is greater than the upper limit threshold of the AC voltage, then the DC voltage regulation reference value of the previous control cycle is decremented, and the decremented value is determined as the current DC voltage regulation reference value.

3. The multi-receiving-end voltage coordinated control method for offshore wind power flexible DC transmission system as described in claim 2, characterized in that, The step of decreasing the DC voltage regulation reference value of the previous control cycle includes: Calculate the difference between the DC voltage regulation reference value of the previous control cycle and the preset step size value; Determine whether the difference is less than a preset DC voltage lower limit threshold; If the difference is not less than the DC voltage lower limit threshold, then the difference is determined as the current DC voltage regulation reference value; If the difference is less than the DC voltage lower limit threshold, then the DC voltage lower limit threshold is determined as the current DC voltage regulation reference value.

4. The multi-receiving-end voltage coordinated control method for offshore wind power flexible DC transmission system as described in claim 3, characterized in that, The step of calculating and generating the current DC voltage reference value for each receiving-end converter station based on the real-time AC line power value, the preset AC line power reference value for each receiving-end converter station, the preset droop coefficient for each receiving-end converter station, and the current DC voltage regulation reference value includes: For each receiving-end converter station, calculate the difference between the current real-time AC line power value of the receiving-end converter station and the preset AC line power reference value for the current receiving-end converter station, and generate a power deviation value. The power deviation value is weighted using a droop coefficient preset for the current receiving-end converter station to obtain the voltage correction amount; The voltage correction is superimposed on the current DC voltage regulation reference value to obtain the current DC voltage reference value of the receiving-end converter station.

5. The multi-receiving-end voltage coordinated control method for a flexible DC transmission system for offshore wind power as described in claim 4, characterized in that, The calculation generates the current DC voltage reference value for each receiving-end converter station, specifically obtained through the following formula: In the formula, For the first The current DC voltage reference value of the receiving-end converter station For the first Real-time AC line power values ​​of each receiving-end converter station For the first The preset AC line power reference value for each receiving-end converter station For the first The preset droop coefficient for each receiving-end converter station This is the current DC voltage regulation reference value.

6. The multi-receiving-end voltage coordinated control method for a flexible DC transmission system for offshore wind power as described in claim 5, characterized in that, The preset AC line power reference value for each receiving-end converter station is generated in the following manner: Obtain the total rated power of all receiving-end converter stations and the preset power allocation ratio among each receiving-end converter station; According to the preset power allocation ratio, the total rated power is allocated to each receiving-end converter station to obtain the AC line power reference value for each receiving-end converter station.

7. The multi-receiving-end voltage coordinated control method for a flexible DC transmission system for offshore wind power as described in claim 6, characterized in that, The preset droop coefficient for each receiving-end converter station is generated in the following manner: Obtain the maximum and minimum values ​​of the total wind power injected into the offshore wind power flexible DC transmission system; Based on the maximum value of the total wind power, the minimum value of the total wind power, and the total rated power of all receiving-end converter stations, and based on the allowable deviation range of DC voltage during steady-state operation of the system, constraints on the droop coefficient of all receiving-end converter stations are constructed. The value that satisfies the aforementioned constraint is selected as the preset droop coefficient for each receiving-end converter station. The constraints are specifically as follows: In the formula, For the first The preset droop coefficient for each receiving-end converter station This represents the total number of receiving-end converter stations. This represents the maximum value of the total wind power. This represents the minimum total wind power output. The total rated power of all receiving-end converter stations. This refers to the preset DC voltage rating of the offshore wind power flexible DC transmission system. This is the preset allowable deviation coefficient for DC voltage.

8. A multi-receiving-end voltage coordinated control device for an offshore wind power flexible DC transmission system, characterized in that, The offshore wind power flexible DC transmission system includes: an AC collecting bus of offshore wind turbines at the sending end and at least two receiving-end converter stations at the receiving end. The multi-terminal voltage coordinated control device includes: a bus voltage value acquisition module, a regulation triggering module, and a voltage coordinated regulation module; The bus voltage value acquisition module is used to acquire the real-time voltage value of the AC collection bus of the offshore wind turbine in real time according to a preset control cycle. The control triggering module is used to call the voltage collaborative control module after each real-time voltage value is acquired; The voltage coordination control module is used to acquire the real-time AC line power values ​​of the at least two receiving-end converter stations; determine the current DC voltage control reference value based on the real-time voltage value and a preset AC voltage upper limit threshold; calculate and generate the current DC voltage reference value for each receiving-end converter station based on the real-time AC line power value, a preset AC line power reference value for each receiving-end converter station, a preset droop coefficient for each receiving-end converter station, and the current DC voltage control reference value; and control each receiving-end converter station to operate at its current DC voltage reference value based on the current DC voltage reference value of each receiving-end converter station.

9. An electronic device, characterized in that, The system includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the multi-receiving-end voltage coordinated control method for a flexible DC transmission system for offshore wind power as described in any one of claims 1 to 7.

10. A storage medium, characterized in that, The storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device where the storage medium is located to perform the multi-receiving-end voltage coordinated control method of the offshore wind power flexible DC transmission system as described in any one of claims 1 to 7.

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