Method and device for establishing ac voltage of offshore wind power low-frequency ac transmission system

Abstract

The application provides an alternating voltage establishment method and device for a low-frequency alternating current transmission system of offshore wind power. The method comprises the following steps: starting the energy storage device of each energy storage wind turbine, charging the direct current capacitor of the wind turbine converter to a first rated direct current voltage, unlocking the mechanical part and the machine side converter of the energy storage wind turbine, and controlling the direct current voltage of the wind turbine converter to be adjusted to the first rated direct current voltage; starting the communication device of each energy storage wind turbine, transmitting the actual value of the active power of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU, starting the grid side converter of each energy storage wind turbine after the transmission is completed, controlling the alternating voltage of each energy storage wind turbine to rise to a set alternating voltage value, and completing the alternating voltage establishment of the low-frequency alternating current transmission system of offshore wind power at least under the condition that the alternating voltage of each energy storage wind turbine reaches the set alternating voltage value. The problem of active circulating current in the alternating voltage establishment method of the prior art is solved.

Description

Technical Field

[0001] This application relates to the technical field of AC voltage establishment for offshore wind power low-frequency AC transmission systems. Specifically, it relates to a method, apparatus, computer-readable storage medium, and electronic device for establishing AC voltage in offshore wind power low-frequency AC transmission systems. Background Technology

[0002] Large-scale, high-quality development of the wind power industry is an important strategic choice for achieving the "dual carbon" goals. Wind power generation is one of the main energy sources for building a new power system. With the continuous development of wind power generation technology, the scale of wind farms is constantly expanding and gradually extending into deep-sea areas.

[0003] Currently, offshore wind power mainly employs flexible DC transmission systems, relying on offshore converter stations to provide AC voltage support. Offshore converter stations are heavy and bulky, making DC transmission costly. In recent years, scholars have proposed a low-frequency AC transmission technology for offshore wind farms based on DRUs (Diode Rectifier Units). This technology uses a grid-based control strategy to construct low-frequency AC voltage, increasing the length of the AC submarine cable and allowing the offshore converter station to be located onshore, significantly reducing construction costs. This approach has high research value and promising application prospects.

[0004] In the black start process of offshore wind farms, the black start power source needs to first establish the AC voltage of the offshore wind farm. DRUs (Diesel Generator Units) are uncontrollable and have unidirectional power flow, making them unsuitable as black start power sources for offshore wind farms. Existing literature on AC voltage establishment methods using diesel generators as black start power sources does not consider the integration of DRUs, and the synchronous operation capability of diesel engines and grid-connected wind turbine converters during subsequent startup needs further research. Furthermore, configuring large-capacity auxiliary converters and centralized energy storage will reduce the economic advantages of low-frequency AC transmission. Schemes that incorporate small-capacity energy storage devices in a small number of wind turbine units can utilize the grid-connected capability of the wind turbine units to establish AC voltage, while also having lower system construction costs. However, existing schemes do not consider active power distribution during AC voltage establishment, resulting in active power circulation issues. Summary of the Invention

[0005] The main objective of this application is to provide a method, apparatus, computer-readable storage medium, and electronic device for establishing AC voltage in an offshore wind power low-frequency AC transmission system, so as to at least solve the problem that the prior art does not consider the distribution of active power and has active circulating current in the process of establishing AC voltage.

[0006] To achieve the above objectives, according to one aspect of this application, a method for establishing AC voltage in an offshore wind power low-frequency AC transmission system is provided. The offshore wind power low-frequency AC transmission system includes multiple energy storage wind turbines and a DRU (Digital Unit Receiver). Each energy storage wind turbine includes an energy storage device, a wind turbine converter, a turbine-side converter, a grid-side converter, and a communication device. The method includes: activating the energy storage device of each of the energy storage wind turbines; charging the DC capacitor of the wind turbine converter to a first rated DC voltage; unlocking the mechanical parts of the energy storage wind turbine and the turbine-side converter; and controlling the DC voltage of the wind turbine converter to adjust to the first rated DC voltage; activating the communication device of each of the energy storage wind turbines. According to the distance relationship between the energy storage wind turbine and the DRU, the actual active power value of the first energy storage wind turbine is transmitted to the second energy storage wind turbine, wherein the second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU; after the transmission is completed, the grid-side converter of each energy storage wind turbine is started, and the AC voltage of each energy storage wind turbine is controlled to rise to a set AC voltage value. At least when it is determined that the AC voltage of each energy storage wind turbine has reached the set AC voltage value, the AC voltage establishment of the offshore wind power low-frequency AC transmission system is completed.

[0007] Optionally, starting the grid-side converter of each of the energy storage wind turbines and controlling the AC voltage of each of the energy storage wind turbines to rise to a set AC voltage value includes: starting the grid-side converter of each of the energy storage wind turbines, determining the first grid connection point d-axis voltage of each of the energy storage wind turbines, wherein the first grid connection point d-axis voltage is the voltage before conduction; controlling the grid connection point d-axis voltage of each of the energy storage wind turbines to rise to the first grid connection point d-axis voltage; determining the second grid connection point d-axis voltage of each of the energy storage wind turbines, and controlling each of the energy storage wind turbines to rise from the first grid connection point d-axis voltage to the second grid connection point d-axis voltage, wherein the second grid connection point d-axis voltage is the set AC voltage value.

[0008] Optionally, the d-axis voltage of the first grid connection point of each of the energy storage wind turbines is determined, including: according to the first formula: Determine the d-axis voltage of the first grid connection point of the energy storage wind turbine closest to the DRU. According to the second formula: Determine the d-axis voltage of the first grid connection point, excluding the energy storage wind turbine closest to the DRU. Among them, v u The voltage rise rate is t, where t is time and k is the voltage amplitude rise rate. i These are the integral parameters of the active power controller, where s is the Laplace operator, and P... j (j=2,3,…,n) represents the actual active power of this energy storage wind turbine and P. k(k = 1, 2, ..., n-1) is the third energy storage wind turbine, which is adjacent to the local energy storage wind turbine, and the distance between the third energy storage wind turbine and the DRU is less than the distance between the local energy storage wind turbine and the DRU.

[0009] Optionally, determining the d-axis voltage of the second grid connection point of each of the energy storage wind turbines includes: according to the third formula: Determine the d-axis voltage of the second grid connection point for each of the energy storage wind turbines. Among them, u fdi0 P is the d-axis voltage at the first grid connection point of each of the energy storage wind turbines. i * and P i These are the reference value and actual value of the active power of the energy storage wind turbine, k p is the proportional parameter of the active power controller, and s is the Laplace operator.

[0010] Optionally, after determining the d-axis voltage of the first grid connection point of each of the energy storage wind turbines, the method further includes: according to the fourth formula: Determine the target voltage frequency ω of the d-axis voltage at the grid connection point of each of the aforementioned energy storage wind turbines. i * Where ω0 is the initial value of the voltage frequency of the d-axis voltage at the grid connection point of each energy storage wind turbine, and K G and K T These are the proportional and time parameters of the first-order inertial controller, Q. i (i = 1, 2, ..., n) represents the actual reactive power value of each of the energy storage wind turbines, Q i * The reactive power reference value for each of the energy storage wind turbines is s, where s is the Laplace operator; the voltage frequency of each of the energy storage wind turbines is controlled to reach the target voltage frequency.

[0011] Optionally, the AC voltage establishment of the offshore wind power low-frequency AC transmission system is completed at least when the AC voltage of each of the energy storage wind turbines reaches the set AC voltage value, including: when the AC voltage of each of the energy storage wind turbines reaches the set AC voltage value, determining whether the actual active power value of each of the energy storage wind turbines reaches the active power target value; and when the actual active power value of each of the energy storage wind turbines reaches the active power target value, completing the AC voltage establishment of the offshore wind power low-frequency AC transmission system.

[0012] Optionally, before determining whether the actual active power value of each of the energy storage wind turbines reaches the active power target value, the method further includes: according to the fifth formula: Determine the target active power value P i1 , where VdcDRU U is the rated DC voltage of the DRU. g It is the voltage amplitude that needs to be achieved at the AC bus near the DRU, T DRU and X T These are the turns ratio and leakage reactance of the DRU converter transformer, respectively, and n is the number of energy storage wind turbines.

[0013] According to another aspect of this application, an AC voltage establishment device for an offshore wind power low-frequency AC transmission system is provided. The offshore wind power low-frequency AC transmission system includes multiple energy storage wind turbines and a DRU (Digital Unit Receiver). Each energy storage wind turbine includes an energy storage device, a wind turbine converter, a turbine-side converter, a grid-side converter, and a communication device. The device includes: a first starting unit for starting the energy storage device of each of the energy storage wind turbines, charging the DC capacitor of the wind turbine converter to a first rated DC voltage, unlocking the mechanical parts of the energy storage wind turbine and the turbine-side converter, and controlling the DC voltage of the wind turbine converter to adjust to the first rated DC voltage; and a second starting unit for starting the communication device of each of the energy storage wind turbines. The device transmits the actual active power value of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU, wherein the second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU; the control unit is used to start the grid-side converter of each of the energy storage wind turbines after the transmission is completed, control the AC voltage of each of the energy storage wind turbines to rise to a set AC voltage value, and at least when it is determined that the AC voltage of each of the energy storage wind turbines has reached the set AC voltage value, complete the AC voltage establishment of the offshore wind power low-frequency AC transmission system.

[0014] According to another aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to execute any of the described methods for establishing AC voltage in an offshore wind power low-frequency AC transmission system.

[0015] According to another aspect of this application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for performing an AC voltage establishment method for any of the aforementioned offshore wind power low-frequency AC transmission systems.

[0016] Applying the technical solution of this application, the energy storage devices of each energy storage wind turbine are activated, the DC capacitors of the wind turbine converters are charged to the first rated DC voltage, and the mechanical parts and turbine-side converters of the energy storage wind turbines are unlocked, controlling the DC voltage of the wind turbine converters to be adjusted to the first rated DC voltage; the communication devices of each energy storage wind turbine are activated, and the actual active power value of the first energy storage wind turbine is transmitted to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU, wherein the second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU; after the transmission is completed, the grid-side converters of each energy storage wind turbine are activated, and the AC voltage of each energy storage wind turbine is controlled to rise to the set AC voltage value. At least when it is determined that the AC voltage of each energy storage wind turbine has reached the set AC voltage value, the AC voltage establishment of the offshore wind power low-frequency AC transmission system is completed. By comparing the active power of adjacent energy storage wind turbines to calculate and set the AC voltage value, the difference in active power between adjacent energy storage wind turbines is eliminated, and the active power is evenly distributed. This solves the problem of active power circulation that does not consider the distribution of active power in the process of establishing AC voltage in existing technologies. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 A hardware block diagram of a mobile terminal for performing an AC voltage establishment method for an offshore wind power low-frequency AC transmission system, according to an embodiment of this application, is shown.

[0019] Figure 2 A flowchart illustrating an AC voltage establishment method for a low-frequency AC transmission system for offshore wind power according to an embodiment of this application is shown.

[0020] Figure 3 A schematic diagram of the structure of an offshore wind power low-frequency AC transmission system provided according to an embodiment of this application is shown;

[0021] Figure 4 A flowchart illustrating a specific method for establishing AC voltage in an offshore wind power low-frequency AC transmission system according to an embodiment of this application is shown.

[0022] Figure 5 A structural block diagram of an AC voltage establishment device for an offshore wind power low-frequency AC transmission system provided according to an embodiment of this application is shown.

[0023] The above figures include the following reference numerals:

[0024] 102. Processor; 104. Memory; 106. Transmission device; 108. Input / output device. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] As described in the background section, existing technologies do not consider the distribution of active power during the AC voltage establishment process, resulting in active power circulating current. To address the issue of active power circulating current in existing technologies during AC voltage establishment, embodiments of this application provide an AC voltage establishment method, apparatus, computer-readable storage medium, and electronic device for offshore wind power low-frequency AC transmission systems.

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0030] The methods and embodiments provided in this application can be executed on a mobile terminal, computer terminal, or similar computing device. Taking running on a mobile terminal as an example, Figure 1 This is a hardware structure block diagram of a mobile terminal for an AC voltage establishment method of an offshore wind power low-frequency AC transmission system according to an embodiment of the present invention. Figure 1 As shown, a mobile terminal may include one or more ( Figure 1Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. The mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the mobile terminal described above. For example, the mobile terminal may also include components that are more... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0031] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the AC voltage establishment method of the offshore wind power low-frequency AC transmission system in this embodiment of the invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the aforementioned networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. The transmission device 106 is used to receive or send data via a network. Specific examples of the aforementioned networks may include wireless networks provided by the mobile terminal's communication provider. In one instance, the transmission device 106 includes a network interface controller (NIC), which can be connected to other network devices via a base station to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0032] This embodiment provides a method for establishing AC voltage in an offshore wind power low-frequency AC transmission system that runs on a mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0033] Figure 2This is a flowchart illustrating a method for establishing AC voltage in an offshore wind power low-frequency AC transmission system according to an embodiment of this application. The offshore wind power low-frequency AC transmission system includes multiple energy storage wind turbines and DRUs, such as... Figure 3 As shown, the system also includes wind turbine generators, collector lines, AC bus 1, step-up transformer, AC bus 2, converter transformer, MMC, reactive power compensation device, AC filter, and AC system. The aforementioned energy storage wind turbine includes an energy storage device, wind turbine converter, turbine-side converter, grid-side converter, and communication device, such as... Figure 2 As shown, the method includes the following steps:

[0034] Step S201: Start the energy storage device of each of the above-mentioned energy storage wind turbines, charge the DC capacitor of the wind turbine converter to the first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the machine-side converter, and control the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage.

[0035] Specifically, the mechanical part consists of the wind turbine blades and bearings. Unlocking the mechanical part of the energy storage wind turbine requires ensuring that the blades can rotate freely and that the bearings are free from abnormal wear or jamming.

[0036] The turbine-side converter is a device that converts the alternating current (AC) generated by the wind turbine generator into direct current (DC). Maintaining the DC voltage of the converter at its rated value ensures system stability and safety. The converter needs to be commissioned and monitored to ensure the DC voltage remains within the normal range.

[0037] In summary, unlocking the mechanical components and turbine-side converter of the energy storage wind turbine is an important step in ensuring the normal operation of the wind turbine and the safe and stable operation of the power generation system.

[0038] Step S202: Activate the communication device of each of the above-mentioned energy storage wind turbines, and transmit the actual value of the active power of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU. The second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU.

[0039] Specifically, the communication devices of all energy storage wind turbines are activated, and the energy storage wind turbines closer to the DRU transmit the actual value of active power to the adjacent energy storage wind turbines farther from the DRU.

[0040] Step S203: After the transmission is completed, start the grid-side converter of each of the above-mentioned energy storage wind turbines, control the AC voltage of each of the above-mentioned energy storage wind turbines to rise to the set AC voltage value, and at least when it is determined that the AC voltage of each of the above-mentioned energy storage wind turbines has reached the set AC voltage value, the AC voltage establishment of the above-mentioned offshore wind power low-frequency AC transmission system is completed.

[0041] Specifically, by comparing the active power of adjacent energy storage wind turbines and calculating the set AC voltage value (grid connection point d-axis voltage reference value) of each energy storage wind turbine, the active power of each energy storage wind turbine is the same as that of the adjacent energy storage wind turbines, thus achieving the average distribution of active power.

[0042] In this embodiment, the energy storage devices of each energy storage wind turbine are activated to charge the DC capacitor of the wind turbine converter to the first rated DC voltage. The mechanical parts and the turbine-side converter of the energy storage wind turbine are unlocked, and the DC voltage of the wind turbine converter is adjusted to the first rated DC voltage. The communication devices of each energy storage wind turbine are activated, and the actual active power value of the first energy storage wind turbine is transmitted to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU. The second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU. After the transmission is completed, the grid-side converter of each energy storage wind turbine is activated, and the AC voltage of each energy storage wind turbine is controlled to rise to the set AC voltage value. At least when it is determined that the AC voltage of each energy storage wind turbine has reached the set AC voltage value, the AC voltage establishment of the offshore wind power low-frequency AC transmission system is completed. By comparing the active power of adjacent energy storage wind turbines to calculate and set the AC voltage value, the difference in active power between adjacent energy storage wind turbines is eliminated, and the active power is evenly distributed. This solves the problem of active power circulation that does not consider the distribution of active power in the process of establishing AC voltage in existing technologies.

[0043] In the specific implementation process, the grid-side converters of each of the aforementioned energy storage wind turbines are started, and the AC voltage of each of the aforementioned energy storage wind turbines is controlled to rise to a set AC voltage value. This includes: starting the grid-side converters of each of the aforementioned energy storage wind turbines, determining the first grid connection point d-axis voltage of each of the aforementioned energy storage wind turbines, wherein the first grid connection point d-axis voltage is the voltage before conduction; controlling the grid connection point d-axis voltage of each of the aforementioned energy storage wind turbines to rise to the first grid connection point d-axis voltage; determining the second grid connection point d-axis voltage of each of the aforementioned energy storage wind turbines, and controlling each of the aforementioned energy storage wind turbines to rise from the first grid connection point d-axis voltage to the second grid connection point d-axis voltage, wherein the second grid connection point d-axis voltage is the set AC voltage value.

[0044] Specifically, the d-axis voltage of the first grid connection point of each of the above-mentioned energy storage wind turbines is determined, including: according to the first formula: Determine the d-axis voltage of the first grid connection point of the energy storage wind turbine closest to the aforementioned DRU. According to the second formula: Determine the d-axis voltage of the first grid connection point other than the energy storage wind turbine closest to the aforementioned DRU. Among them, v u The voltage rise rate is t, where t is time and k is the voltage amplitude rise rate. iThese are the integral parameters of the active power controller, where s is the Laplace operator, and P... j (j=2,3,…,n) represents the actual active power of this energy storage wind turbine and P. k (k=1,2,…,n-1) is the third energy storage wind turbine. The third energy storage wind turbine is adjacent to the main energy storage wind turbine, and the distance between the third energy storage wind turbine and the DRU is less than the distance between the main energy storage wind turbine and the DRU.

[0045] More specifically, the d-axis voltage of the second grid connection point of each of the aforementioned energy storage wind turbines is determined, including: according to the third formula: Determine the d-axis voltage of the second grid connection point for each of the aforementioned energy storage wind turbines. Among them, u fdi0 P is the d-axis voltage at the first grid connection point of each of the aforementioned energy storage wind turbines. i * and P i These are the reference and actual active power values ​​for the aforementioned energy storage wind turbines, k p is the proportional parameter of the active power controller, and s is the Laplace operator.

[0046] This method simultaneously activates the grid-side converters of all energy storage wind turbines, controlling the AC voltage amplitude of each of the aforementioned energy storage wind turbines to rise linearly, with the AC voltage amplitude rise time being t. u Calculate the frequency reference value of the grid-side converter and the first reference value of the d-axis voltage at the grid connection point, and set the reference value of the q-axis voltage at the grid connection point to 0;

[0047] The reference value for the d-axis voltage at the grid connection point of the grid-side converter of the energy storage wind turbine closest to the DRU is: Among them, v u The voltage amplitude rises at a rate of t, where t is time.

[0048] The reference value for the d-axis voltage at the grid connection point of other energy storage wind turbine grid-side converters is:

[0049] Among them, v u The voltage rise rate is t, where t is time and k is the voltage amplitude rise rate. i These are the integral parameters of the active power controller. P j (j = 2, 3, ..., n) and P k (k = 1, 2, ..., n-1) represents the actual active power of this energy storage wind turbine and the actual active power of adjacent energy storage wind turbines.

[0050] During the AC voltage boosting process, the reference value of the d-axis voltage at the grid connection point is calculated by comparing the actual active power values ​​of adjacent energy storage wind turbines. In this way, the active power of each energy storage wind turbine is the same as that of its adjacent counterparts, and the active power of all energy storage wind turbines is the same, thus achieving an average distribution of active power.

[0051] Furthermore, after determining the d-axis voltage of the first grid connection point for each of the aforementioned energy storage wind turbines, the method further includes: according to the fourth formula: Determine the target voltage frequency ω of the d-axis voltage at the grid connection point of each of the aforementioned energy storage wind turbines. i * Where ω0 is the initial value of the voltage frequency of the d-axis voltage at the grid connection point of each of the above-mentioned energy storage wind turbines, and K G and K T These are the proportional and time parameters of the first-order inertial controller, Q. i (i = 1, 2, ..., n) represents the actual reactive power value of each of the above-mentioned energy storage wind turbines, Q i * Here is the reactive power reference value for each of the above-mentioned energy storage wind turbines, and s is the Laplace operator; the voltage frequency of each of the above-mentioned energy storage wind turbines is controlled to reach the target voltage frequency.

[0052] This method also requires calculating the voltage frequency of each energy storage wind turbine to ensure that all turbines operate at the same frequency. Maintaining identical AC voltage frequencies across all turbines ensures coordinated operation within the system. When all turbines operate at the same frequency, equipment damage or grid instability caused by voltage instability or frequency discrepancies can be avoided. Furthermore, synchronized voltage frequencies also facilitate energy complementarity and balance between turbines, improving the overall system efficiency and stability. Therefore, controlling the AC voltage frequency of all energy storage wind turbines to be identical is a crucial measure to ensure normal system operation and improve overall performance.

[0053] Furthermore, at least when it is determined that the AC voltage of each of the aforementioned energy storage wind turbines reaches the aforementioned set AC voltage value, the AC voltage establishment of the aforementioned offshore wind power low-frequency AC transmission system is completed, including: when it is determined that the AC voltage of each of the aforementioned energy storage wind turbines reaches the aforementioned set AC voltage value, determining whether the actual value of the active power of each of the aforementioned energy storage wind turbines reaches the active power target value; and when the actual value of the active power of each of the aforementioned energy storage wind turbines reaches the aforementioned active power target value, the AC voltage establishment of the aforementioned offshore wind power low-frequency AC transmission system is completed.

[0054] Specifically, before determining whether the actual active power value of each of the aforementioned energy storage wind turbines reaches the active power target value, the above method also includes: according to the fifth formula: Determine the above active power target value P i1 , where V dcDRU This is the DC voltage rating of the aforementioned DRU, U g This refers to the required voltage amplitude, T, at the AC busbar near the aforementioned DRU. DRU and X TThese are the turns ratio and leakage reactance of the aforementioned DRU converter transformer, respectively, and n is the number of the aforementioned energy storage wind turbines.

[0055] This method calculates the active power P that the energy storage wind turbine needs to generate based on the required voltage amplitude Ug at the AC bus. i1 When the energy storage wind turbine outputs active power P i1 At that time, the AC voltage amplitude of the AC bus reaches Ug, which confirms that the requirements for establishing AC voltage are met.

[0056] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the AC voltage establishment method of the offshore wind power low-frequency AC transmission system of this application will be described in detail below with reference to specific embodiments.

[0057] This embodiment relates to a specific method for establishing AC voltage in an offshore wind power low-frequency AC transmission system, such as... Figure 4 As shown, it includes the following steps:

[0058] (1) Start the energy storage device of the energy storage wind turbine and charge the DC capacitor of the wind turbine converter to the rated DC voltage.

[0059] (2) Unlock the mechanical parts and the machine-side converter of the energy storage wind turbine, and control the DC voltage of the wind turbine converter to the rated value.

[0060] (3) Start the communication device of all energy storage wind turbines. The energy storage wind turbines closer to the DRU will transmit the actual value of active power to the adjacent energy storage wind turbines farther away from the DRU.

[0061] (4) Simultaneously start the grid-side converters of all energy storage wind turbines, and control the AC voltage amplitude to rise linearly. The AC voltage amplitude rise time is t. u Calculate the frequency reference value of the grid-side converter and the first reference value of the d-axis voltage at the grid connection point, setting the q-axis voltage reference value at the grid connection point to 0. The frequency reference value of the grid-side converter for the energy storage wind turbine is:

[0062]

[0063] Where ω0 is the initial value of the voltage frequency, K G and K T These are the proportional and time parameters of the first-order inertial controller, Q. i (i = 1, 2, ..., n) represents the actual reactive power of the energy storage wind turbine, Q i * This is a reference value for the reactive power of the energy storage wind turbine.

[0064] The reference value for the d-axis voltage at the grid connection point of the grid-side converter of the energy storage wind turbine closest to the DRU is:

[0065] Among them, v u The voltage amplitude rises at a rate of t, where t is time.

[0066] The reference value for the d-axis voltage at the grid connection point of other energy storage wind turbine grid-side converters is:

[0067]

[0068] Among them, v u The voltage rise rate is t, where t is time and k is the voltage amplitude rise rate. i These are the integral parameters of the active power controller. P j (j = 2, 3, ..., n) and P k (k = 1, 2, ..., n-1) represents the actual active power of this energy storage wind turbine and the actual active power of adjacent energy storage wind turbines.

[0069] During the AC voltage boosting process, the reference value of the d-axis voltage at the grid connection point is calculated by comparing the actual active power values ​​of adjacent energy storage wind turbines. In this way, the active power of each energy storage wind turbine is the same as that of its adjacent counterparts, and the active power of all energy storage wind turbines is the same, thus achieving an average distribution of active power.

[0070] (5) After time t u Afterwards, the energy storage wind turbine records the reference value u of the d-axis voltage at the grid connection point at this time. fdi0 and the actual value of active power P i0 The second reference value of the d-axis voltage at the grid connection point is calculated, and the active power generated by the energy storage wind turbine is linearly increased to bring the voltage of the offshore wind farm close to its rated value. The second reference value of the d-axis voltage at the grid connection point of the energy storage wind turbine is:

[0071]

[0072] Among them, u fdi0 For time t u Reference value of d-axis voltage at grid connection point of the energy storage wind turbine, P i * and P i These are the reference and actual active power values ​​for energy storage wind turbines; k p This is the proportional parameter of the active power controller. During this process, the active power reference value P... i * By P i0 Linear rise to P i1 P i1 for:

[0073]

[0074] Among them, V dcDRU This is the rated DC voltage of the DRU, Ug Is it like this? Figure 3 The required voltage amplitude, T, at AC bus 2 shown. DRU and X T These are the turns ratio and leakage reactance of the DRU converter transformer, respectively, and n is the number of energy storage wind turbines. Thus, the active power generated by the energy storage wind turbines is controlled to P. i1 The AC voltage amplitude at AC bus 2 reaches U g The AC voltage has been established.

[0075] This embodiment establishes the AC voltage of the low-frequency system using wind turbines equipped with a small number of energy storage devices. During the linear rise of the AC voltage, the active power of adjacent energy storage wind turbines is compared to calculate the reference value of the grid connection point voltage amplitude, eliminating differences in active power between adjacent energy storage wind turbines and achieving an even distribution of active power. The required active power output of the energy storage wind turbines is calculated based on the desired AC voltage amplitude, and the active power output of the energy storage wind turbines is controlled to ensure that the AC voltage amplitude meets the voltage establishment requirements.

[0076] This application also provides an AC voltage establishment device for an offshore wind power low-frequency AC transmission system. It should be noted that this AC voltage establishment device for an offshore wind power low-frequency AC transmission system can be used to execute the AC voltage establishment method for an offshore wind power low-frequency AC transmission system provided in this application. This device is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0077] The following describes the AC voltage establishment device for the offshore wind power low-frequency AC transmission system provided in the embodiments of this application.

[0078] Figure 5 This is a schematic diagram of an AC voltage establishment device for an offshore wind power low-frequency AC transmission system according to an embodiment of this application. The offshore wind power low-frequency AC transmission system includes multiple energy storage wind turbines and a DRU (Device Receiver Unit). The energy storage wind turbines include energy storage devices, turbine converters, turbine-side converters, grid-side converters, and communication devices, such as... Figure 5 As shown, the device includes:

[0079] The first starting unit 51 is used to start the energy storage device of each of the above-mentioned energy storage wind turbines, charge the DC capacitor of the wind turbine converter to the first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the machine-side converter, and control the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage.

[0080] The second starting unit 52 is used to start the communication device of each of the above-mentioned energy storage wind turbines, and transmit the actual value of the active power of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU. The second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU.

[0081] The control unit 53 is used to start the grid-side converter of each of the above-mentioned energy storage wind turbines after the transmission is completed, control the AC voltage of each of the above-mentioned energy storage wind turbines to rise to a set AC voltage value, and at least when it is determined that the AC voltage of each of the above-mentioned energy storage wind turbines has reached the set AC voltage value, complete the AC voltage establishment of the above-mentioned offshore wind power low-frequency AC transmission system.

[0082] In this embodiment, a first starting unit is used to start the energy storage device of each of the aforementioned energy storage wind turbines, charge the DC capacitor of the wind turbine converter to a first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the turbine-side converter, and control the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage; a second starting unit is used to start the communication device of each of the aforementioned energy storage wind turbines, and transmit the actual active power value of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU, wherein the second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU; a control unit is used to start the grid-side converter of each of the aforementioned energy storage wind turbines after the transmission is completed, control the AC voltage of each of the aforementioned energy storage wind turbines to rise to a set AC voltage value, and at least when it is determined that the AC voltage of each of the aforementioned energy storage wind turbines has reached the set AC voltage value, complete the AC voltage establishment of the offshore wind power low-frequency AC transmission system. By comparing the active power of adjacent energy storage wind turbines to calculate and set the AC voltage value, the difference in active power between adjacent energy storage wind turbines is eliminated, and the active power is evenly distributed. This solves the problem of active power circulation that does not consider the distribution of active power in the process of establishing AC voltage in existing technologies.

[0083] As an optional solution, the control unit includes a first determining module, a first controlling module, and a second determining module; the first determining module is used to start the grid-side converter of each of the above-mentioned energy storage wind turbines, and determine the first grid connection point d-axis voltage of each of the above-mentioned energy storage wind turbines, wherein the first grid connection point d-axis voltage is the voltage before conduction; the first controlling module is used to control the grid connection point d-axis voltage of each of the above-mentioned energy storage wind turbines to rise to the first grid connection point d-axis voltage; the second determining module is used to determine the second grid connection point d-axis voltage of each of the above-mentioned energy storage wind turbines, and control each of the above-mentioned energy storage wind turbines to rise from the first grid connection point d-axis voltage to the second grid connection point d-axis voltage, wherein the second grid connection point d-axis voltage is the set AC voltage value.

[0084] In one optional embodiment, the first determining module includes a first determining submodule and a second determining submodule; the first determining submodule is used to determine the first formula: Determine the d-axis voltage of the first grid connection point of the energy storage wind turbine closest to the aforementioned DRU. The second determining submodule is used to determine the second formula: Determine the d-axis voltage of the first grid connection point other than the energy storage wind turbine closest to the aforementioned DRU. Among them, v u The voltage rise rate is t, where t is time and k is the voltage amplitude rise rate. i These are the integral parameters of the active power controller, where s is the Laplace operator, and P... j (j=2,3,…,n) represents the actual active power of this energy storage wind turbine and P. k (k=1,2,…,n-1) is the third energy storage wind turbine. The third energy storage wind turbine is adjacent to the main energy storage wind turbine, and the distance between the third energy storage wind turbine and the DRU is less than the distance between the main energy storage wind turbine and the DRU.

[0085] In one alternative approach, the second determining module includes a third determining submodule, used to determine according to a third formula: Determine the d-axis voltage of the second grid connection point for each of the aforementioned energy storage wind turbines. Among them, u fdi0 P is the d-axis voltage at the first grid connection point of each of the aforementioned energy storage wind turbines. i * and P i These are the reference and actual active power values ​​for the aforementioned energy storage wind turbines, k p is the proportional parameter of the active power controller, and s is the Laplace operator.

[0086] In an optional embodiment, the control unit further includes a third determining module and a second control module. The third determining module is used to determine the d-axis voltage at the first grid connection point of each of the aforementioned energy storage wind turbines, according to a fourth formula: Determine the target voltage frequency ω of the d-axis voltage at the grid connection point of each of the aforementioned energy storage wind turbines. i * Where ω0 is the initial value of the voltage frequency of the d-axis voltage at the grid connection point of each of the above-mentioned energy storage wind turbines, and K G and K T These are the proportional and time parameters of the first-order inertial controller, Q. i (i = 1, 2, ..., n) represents the actual reactive power value of each of the above-mentioned energy storage wind turbines, Q i * Here, s represents the reactive power reference value for each of the aforementioned energy storage wind turbines, and s is the Laplace operator; the second control module is used to control the voltage frequency of each of the aforementioned energy storage wind turbines to reach the aforementioned target voltage frequency.

[0087] In one optional embodiment, the control unit further includes a fourth determining module and a fifth determining module; the fourth determining module is used to determine whether the actual value of the active power of each of the aforementioned energy storage wind turbines reaches the target value of active power when the AC voltage of each of the aforementioned energy storage wind turbines reaches the aforementioned set AC voltage value; the fifth determining module is used to complete the AC voltage establishment of the aforementioned offshore wind power low-frequency AC transmission system when the actual value of the active power of each of the aforementioned energy storage wind turbines reaches the aforementioned target value of active power.

[0088] In an optional embodiment, the control unit further includes a sixth determining module, used to determine, before determining whether the actual active power value of each of the aforementioned energy storage wind turbines reaches the active power target value, according to the fifth formula: Determine the above active power target value P i1 , where V dcDRU This is the DC voltage rating of the aforementioned DRU, U g This refers to the required voltage amplitude, T, at the AC busbar near the aforementioned DRU. DRU and X T These are the turns ratio and leakage reactance of the aforementioned DRU converter transformer, respectively, and n is the number of the aforementioned energy storage wind turbines.

[0089] The AC voltage establishment device of the aforementioned offshore wind power low-frequency AC transmission system includes a processor and a memory. The first start-up unit, the second start-up unit, the control unit, etc., are all stored as program units in the memory, and the processor executes the program units stored in the memory to achieve the corresponding functions. All of the above modules are located in the same processor; or, the above modules are located in different processors in any combination.

[0090] The processor contains a kernel, which retrieves the corresponding program unit from memory. One or more kernels can be configured. By adjusting kernel parameters, the problem of active power circulation current, which is not considered in the current AC voltage setup process, can be addressed.

[0091] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0092] This invention provides a computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform the AC voltage establishment method of the offshore wind power low-frequency AC transmission system.

[0093] Specifically, the methods for establishing the AC voltage of offshore wind power low-frequency AC transmission systems include:

[0094] Step S201: Start the energy storage device of each of the above-mentioned energy storage wind turbines, charge the DC capacitor of the wind turbine converter to the first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the machine-side converter, and control the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage.

[0095] Step S202: Activate the communication device of each of the above-mentioned energy storage wind turbines, and transmit the actual value of the active power of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU. The second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU.

[0096] Step S203: After the transmission is completed, start the grid-side converter of each of the above-mentioned energy storage wind turbines, control the AC voltage of each of the above-mentioned energy storage wind turbines to rise to the set AC voltage value, and at least when it is determined that the AC voltage of each of the above-mentioned energy storage wind turbines has reached the set AC voltage value, the AC voltage establishment of the above-mentioned offshore wind power low-frequency AC transmission system is completed.

[0097] This invention provides a processor for running a program, wherein the program executes the AC voltage establishment method of the offshore wind power low-frequency AC transmission system.

[0098] Specifically, the methods for establishing the AC voltage of offshore wind power low-frequency AC transmission systems include:

[0099] Step S201: Start the energy storage device of each of the above-mentioned energy storage wind turbines, charge the DC capacitor of the wind turbine converter to the first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the machine-side converter, and control the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage.

[0100] Step S202: Activate the communication device of each of the above-mentioned energy storage wind turbines, and transmit the actual value of the active power of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU. The second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU.

[0101] Step S203: After the transmission is completed, start the grid-side converter of each of the above-mentioned energy storage wind turbines, control the AC voltage of each of the above-mentioned energy storage wind turbines to rise to the set AC voltage value, and at least when it is determined that the AC voltage of each of the above-mentioned energy storage wind turbines has reached the set AC voltage value, the AC voltage establishment of the above-mentioned offshore wind power low-frequency AC transmission system is completed.

[0102] This invention provides an electronic device, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs at least the following steps:

[0103] Step S201: Start the energy storage device of each of the above-mentioned energy storage wind turbines, charge the DC capacitor of the wind turbine converter to the first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the machine-side converter, and control the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage.

[0104] Step S202: Activate the communication device of each of the above-mentioned energy storage wind turbines, and transmit the actual value of the active power of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU. The second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU.

[0105] Step S203: After the transmission is completed, start the grid-side converter of each of the above-mentioned energy storage wind turbines, control the AC voltage of each of the above-mentioned energy storage wind turbines to rise to the set AC voltage value, and at least when it is determined that the AC voltage of each of the above-mentioned energy storage wind turbines has reached the set AC voltage value, the AC voltage establishment of the above-mentioned offshore wind power low-frequency AC transmission system is completed.

[0106] The devices mentioned in this article can be servers, PCs, tablets, mobile phones, etc.

[0107] This application also provides a computer program product, which, when executed on a data processing device, is suitable for executing an initialization program having at least the following method steps:

[0108] Step S201: Start the energy storage device of each of the above-mentioned energy storage wind turbines, charge the DC capacitor of the wind turbine converter to the first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the machine-side converter, and control the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage.

[0109] Step S202: Activate the communication device of each of the above-mentioned energy storage wind turbines, and transmit the actual value of the active power of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU. The second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU.

[0110] Step S203: After the transmission is completed, start the grid-side converter of each of the above-mentioned energy storage wind turbines, control the AC voltage of each of the above-mentioned energy storage wind turbines to rise to the set AC voltage value, and at least when it is determined that the AC voltage of each of the above-mentioned energy storage wind turbines has reached the set AC voltage value, the AC voltage establishment of the above-mentioned offshore wind power low-frequency AC transmission system is completed.

[0111] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0112] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0113] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0114] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0115] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0116] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0117] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0118] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0119] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0120] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0121] 1) A method for establishing AC voltage in an offshore wind power low-frequency AC transmission system according to this application. The offshore wind power low-frequency AC transmission system includes multiple energy storage wind turbines and DRUs. The energy storage wind turbines include energy storage devices, wind turbine converters, turbine-side converters, grid-side converters, and communication devices. The method includes: starting the energy storage devices of each of the aforementioned energy storage wind turbines, charging the DC capacitors of the wind turbine converters to a first rated DC voltage, and unlocking the mechanical parts of the energy storage wind turbines and the turbine-side converters, controlling the DC voltage of the wind turbine converters to adjust to the first rated DC voltage; starting the communication devices of each of the aforementioned energy storage wind turbines, and according to the aforementioned energy storage... The distance relationship between the wind turbine and the aforementioned DRU is used to transmit the actual active power value of the first energy storage wind turbine to the second energy storage wind turbine. The second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the aforementioned DRU is less than the distance between the second energy storage wind turbine and the aforementioned DRU. After the transmission is completed, the grid-side converters of each of the aforementioned energy storage wind turbines are activated to control the AC voltage of each of the aforementioned energy storage wind turbines to rise to a set AC voltage value. At least after confirming that the AC voltage of each of the aforementioned energy storage wind turbines has reached the set AC voltage value, the AC voltage establishment of the aforementioned offshore wind power low-frequency AC transmission system is completed. By comparing the active power of adjacent energy storage wind turbines to calculate the set AC voltage value, the difference in active power between adjacent energy storage wind turbines is eliminated, achieving an average distribution of active power. This solves the problem of active power circulation current in existing technologies that do not consider active power distribution during AC voltage establishment.

[0122] 2) An AC voltage establishment device for an offshore wind power low-frequency AC transmission system according to this application, wherein the offshore wind power low-frequency AC transmission system includes multiple energy storage wind turbines and DRUs, wherein the energy storage wind turbines include energy storage devices, wind turbine converters, turbine-side converters, grid-side converters, and communication devices. The device includes: a first starting unit, used to start the energy storage devices of each of the aforementioned energy storage wind turbines, charge the DC capacitors of the wind turbine converters to a first rated DC voltage, unlock the mechanical parts of the energy storage wind turbines and the turbine-side converters, and control the DC voltage of the wind turbine converters to adjust to the first rated DC voltage; and a second starting unit, used to start the communication devices of each of the aforementioned energy storage wind turbines. Based on the distance relationship between the aforementioned energy storage wind turbines and the aforementioned DRUs, the actual active power value of the first energy storage wind turbine is transmitted to the second energy storage wind turbine. The second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the aforementioned DRU is less than the distance between the second energy storage wind turbine and the aforementioned DRU. A control unit is used to, after the transmission is completed, activate the grid-side converter of each of the aforementioned energy storage wind turbines, controlling the AC voltage of each of the aforementioned energy storage wind turbines to rise to a set AC voltage value. At least after confirming that the AC voltage of each of the aforementioned energy storage wind turbines has reached the set AC voltage value, the AC voltage establishment of the aforementioned offshore wind power low-frequency AC transmission system is completed. By comparing the active power of adjacent energy storage wind turbines to calculate the set AC voltage value, the difference in active power between adjacent energy storage wind turbines is eliminated, achieving an average distribution of active power. This solves the problem of active power circulation current in existing technologies that do not consider active power distribution during AC voltage establishment.

[0123] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for AC voltage build-up of an offshore wind power low frequency AC transmission system, characterized in that, The offshore wind power low-frequency AC transmission system includes a plurality of energy storage wind turbines and a DRU, the energy storage wind turbine includes an energy storage device, a wind turbine converter, a machine side converter, a grid side converter, a communication device, and the method includes: starting the energy storage device of each energy storage wind turbine, charging the DC capacitor of the wind turbine converter to a first rated DC voltage, and unlocking the mechanical part of the energy storage wind turbine and the machine side converter, controlling the DC voltage adjustment of the wind turbine converter to the first rated DC voltage; starting the communication device of each energy storage wind turbine, transmitting the active power actual value of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbine and the DRU, wherein the second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU; after the transmission is completed, starting the grid side converter of each energy storage wind turbine, controlling the AC voltage of each energy storage wind turbine to rise to a set AC voltage value, and at least in the case where it is determined that the AC voltage of each energy storage wind turbine reaches the set AC voltage value, completing the AC voltage establishment of the offshore wind power low-frequency AC transmission system; at least in the case where it is determined that the AC voltage of each energy storage wind turbine reaches the set AC voltage value, completing the AC voltage establishment of the offshore wind power low-frequency AC transmission system, including: in the case where it is determined that the AC voltage of each energy storage wind turbine reaches the set AC voltage value, determining whether the active power actual value of each energy storage wind turbine reaches an active power target value; in the case where the active power actual value of each energy storage wind turbine reaches the active power target value, completing the AC voltage establishment of the offshore wind power low-frequency AC transmission system; Before determining whether the actual value of the active power of each of the energy storage wind turbines reaches the target value of the active power, the method further comprises: determining the target value of the active power P according to a fifth formula: i1 wherein V dcDRU is a DC voltage rating of the DRU, U g is a voltage amplitude required to be reached at an AC bus close to the DRU, T DRU and X T are a transformation ratio and leakage reactance of a converter transformer of the DRU, respectively, and n is a number of the energy storage wind turbines.

2. The method of claim 1, wherein, starting the grid side converter of each energy storage wind turbine, and controlling the AC voltage of each energy storage wind turbine to rise to a set AC voltage value, including: starting the grid side converter of each energy storage wind turbine, and respectively determining the first grid connection point d-axis voltage of each energy storage wind turbine, wherein the first grid connection point d-axis voltage is the voltage before conduction; controlling the grid connection point d-axis voltage of each energy storage wind turbine to rise to the first grid connection point d-axis voltage; determining the second grid connection point d-axis voltage of each energy storage wind turbine, and controlling each energy storage wind turbine to rise from the first grid connection point d-axis voltage to the second grid connection point d-axis voltage, wherein the second grid connection point d-axis voltage is the set AC voltage value.

3. The method of claim 2, wherein, respectively determining the first grid connection point d-axis voltage of each energy storage wind turbine, including: According to a first formula: , the first point of grid connection d-axis voltage of the energy storage wind turbine closest to the DRU distance is determined ; According to the second formula: , the first grid-connected point d-axis voltage is determined except for the energy storage fan closest to the DRU distance ; wherein v u is the AC voltage amplitude rise rate, t is time, k i is the integral parameter of the active power controller, s is the Laplace operator, P j is the actual value of the active power of the local energy storage fan, j = 2, 3, …, n, P k is the actual value of the active power of the third energy storage fan, k = 1, 2, …, n-1, the third energy storage fan is adjacent to the local energy storage fan, and the distance between the third energy storage fan and the DRU is less than the distance between the local energy storage fan and the DRU.

4. The method of claim 2, wherein, determining the second grid connection point d-axis voltage of each energy storage wind turbine, including: According to the third formula: , the second grid-connected point d-axis voltage of each energy storage fan is determined , wherein, is the first grid-connected point d-axis voltage of each energy storage fan, P i * and P i is the active power reference value and the active power actual value of the energy storage fan, k p is the proportional parameter of the active power controller, and s is the Laplace operator.

5. The method of claim 2, wherein, after respectively determining the first grid connection point d-axis voltage of each energy storage wind turbine, the method further includes: According to the fourth formula: , the target voltage frequency of the grid-connected point d-axis voltage of each energy storage fan is determined , wherein ω0 is the initial value of the voltage frequency of the grid-connected point d-axis voltage of each energy storage fan, K G and K T are the proportional parameter and the time parameter of the first-order inertia controller, respectively, Q i is the actual value of the reactive power of each energy storage fan, i = 1, 2, …, n, Q i * is the reference value of the reactive power of each energy storage fan, and s is the Laplace operator. controlling the voltage frequency of each energy storage wind turbine to reach the target voltage frequency.

6. An AC voltage building device for an offshore wind power low frequency AC transmission system, characterized in that, The offshore wind power low-frequency AC transmission system includes a plurality of energy storage wind turbines and a DRU, the energy storage wind turbine includes an energy storage device, a wind turbine converter, a machine side converter, a grid side converter, a communication device, and the device includes: The first starting unit is configured to start the energy storage device of each of the energy storage wind turbines, charge the DC capacitor of the wind turbine converter to a first rated DC voltage, and unlock the mechanical part of the energy storage wind turbine and the machine-side converter, and control the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage. The second starting unit is configured to start the communication device of each of the energy storage wind turbines, and transmit the active power actual value of the first energy storage wind turbine to the second energy storage wind turbine according to the distance relationship between the energy storage wind turbines and the DRU, wherein the second energy storage wind turbine is adjacent to the first energy storage wind turbine, and the distance between the first energy storage wind turbine and the DRU is less than the distance between the second energy storage wind turbine and the DRU. The control unit is configured to start the grid-side converter of each of the energy storage wind turbines after the transmission is completed, control the AC voltage of each of the energy storage wind turbines to rise to a set AC voltage value, and complete the AC voltage establishment of the offshore wind power low-frequency AC transmission system at least in the case where it is determined that the AC voltage of each of the energy storage wind turbines reaches the set AC voltage value. The control unit further comprises a fourth determination module and a fifth determination module. The fourth determination module is configured to determine whether the active power actual value of each of the energy storage wind turbines reaches an active power target value in the case where it is determined that the AC voltage of each of the energy storage wind turbines reaches the set AC voltage value. The fifth determination module is configured to complete the AC voltage establishment of the offshore wind power low-frequency AC transmission system in the case where the active power actual value of each of the energy storage wind turbines reaches the active power target value. The control unit further comprises a sixth determining module, configured to determine the active power target value P according to a fifth formula before determining whether the active power actual value of each energy storage fan reaches the active power target value P i1 , wherein V dcDRU is a DC voltage rated value of the DRU, U g is a voltage amplitude required to be reached at an AC bus close to the DRU, T DRU and X T are a transformation ratio and leakage reactance of a converter transformer of the DRU respectively, and n is a number of the energy storage fans.

7. A computer readable storage medium characterized by The computer readable storage medium comprises a stored program, wherein the program controls the device where the computer readable storage medium is located to perform the AC voltage establishment method of the offshore wind power low-frequency AC transmission system according to any one of claims 1 to 5 when the program is running.

8. An electronic device, comprising: The computer readable storage medium comprises a stored program, wherein the program controls the device where the computer readable storage medium is located to perform the AC voltage establishment method of the offshore wind power low-frequency AC transmission system according to any one of claims 1 to 5 when the program is running. The computer readable storage medium comprises a stored program, wherein the program controls the device where the computer readable storage medium is located to perform the AC voltage establishment method of the offshore wind power low-frequency AC transmission system according to any one of claims 1 to 5 when the program is running. The computer readable storage medium comprises a stored program, wherein the program controls the device where the computer readable storage medium is located to perform the AC voltage establishment method of the offshore wind power low-frequency AC transmission system according to any one of claims 1 to 5 when the program is running.

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