Alternating-current voltage establishing method and device of offshore wind power low-frequency alternating-current sending-out system

Abstract

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

Description

Technical Field

[0001] The present application relates to the technical field of establishing AC voltage in an offshore wind power low-frequency AC transmission system, and specifically, to a method, device, computer-readable storage medium and electronic device for establishing AC voltage in an offshore wind power low-frequency AC transmission system. Background Art

[0002] Large-scale and high-quality development of the wind power industry is an important strategic choice for implementing the "dual carbon" goals and tasks. 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 continues to expand and gradually expand to deep sea areas.

[0003] At present, offshore wind power mainly adopts flexible direct current transmission system, relying on offshore converter stations to provide AC voltage support. The weight and volume of offshore converter station equipment are large, and the cost of the technical solution of DC transmission is high. In recent years, some scholars have proposed a technical solution for low-frequency AC transmission of offshore wind farms based on DRU (Diode Rectifier Unit). The wind turbine converter adopts a grid-type control strategy to construct low-frequency AC voltage, increases the length of the AC submarine cable, and places the offshore converter station on land, which can greatly reduce the construction cost. It has high research value and good application prospects.

[0004] During the black start process of an offshore wind farm, the black start power supply needs to first establish the AC voltage of the offshore wind farm. The DRU is uncontrollable and has unidirectional current flow, so it cannot be used as a black start power supply for an offshore wind farm. In existing literature, the methods for establishing AC voltage using diesel generators as black start power supplies have not considered the case of connecting to the DRU, and the ability of the diesel engine and the grid-type wind turbine converter to operate synchronously during the subsequent startup process needs to be studied. The solution of configuring large-capacity auxiliary converters and centralized energy storage will reduce the economic advantage of low-frequency AC transmission. The solution of setting up a small-capacity energy storage device in a small number of wind turbines can use the grid-building capacity of the wind turbines to establish AC voltage, and the system construction cost is relatively low. However, the existing solutions do not consider the distribution of active power in the process of establishing AC voltage, and there is a problem of active circulation. Summary of the invention

[0005] The main purpose of the present application is to provide a method, device, 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 existing technology does not consider the distribution of active power during the establishment of AC voltage and there is active circulating current.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a method for establishing AC voltage of 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 DRUs. The energy storage wind turbines include energy storage devices, wind turbine converters, machine-side converters, grid-side converters, and communication devices. The method includes: starting the energy storage devices of each of the energy storage wind turbines, charging the DC capacitors of the wind turbine converters to a first rated DC voltage, unlocking the mechanical part of the energy storage wind turbine and the machine-side converter, and controlling the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage; starting the communication devices of each of the energy storage wind turbines; The actual value of the active power 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 converter of each of the energy storage wind turbines is started, and the AC voltage of each of the energy storage wind turbines is controlled 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 reaches the set AC voltage value, the AC voltage establishment of the offshore wind power low-frequency AC transmission system is completed.

[0007] Optionally, the grid-side converter of each of the energy storage wind turbines is started, and the AC voltage of each of the energy storage wind turbines is controlled to rise to a set AC voltage value, including: starting the grid-side converter of each of the energy storage wind turbines, and respectively determining the first grid-connected point d-axis voltage of each of the energy storage wind turbines, wherein the first grid-connected point d-axis voltage is the voltage before conduction; controlling the grid-connected point d-axis voltage of each of the energy storage wind turbines to be boosted to the first grid-connected point d-axis voltage; determining the second grid-connected 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-connected point d-axis voltage to the second grid-connected point d-axis voltage, wherein the second grid-connected point d-axis voltage is the set AC voltage value.

[0008] Optionally, respectively determining the d-axis voltage of the first grid connection point of each of the energy storage wind turbines comprises: according to a 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 except the energy storage wind turbine closest to the DRU Among them, v u is the rate of increase of the AC voltage amplitude, t is the time, k i is the integral parameter of the active power controller, s is the Laplace operator, P j (j=2,3,…,n) is the actual value of 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 current energy storage wind turbine, and the distance between the third energy storage wind turbine and the DRU is smaller than the distance between the current 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 a third formula: Determine the d-axis voltage of the second grid connection point of each of the energy storage wind turbines Among them, u fdi0 is the d-axis voltage of the first grid-connected point of each of the energy storage wind turbines, P i * and P i is the active power reference value and the actual active power value of the energy storage fan, k p is the proportional parameter of the active power controller, and s is the Laplace operator.

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

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

[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 active power target value P i1 , where VdcDRU is the DC voltage rating of the DRU, U g is the voltage amplitude that needs to be reached at the AC bus near the DRU, T DRU and X T are respectively the transformation ratio and leakage reactance of the DRU converter, and n is the number of the energy storage wind turbines.

[0013] According to another aspect of the present application, an AC voltage establishing 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 DRUs. The energy storage wind turbines include energy storage devices, wind turbine converters, machine-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 energy storage wind turbines, charge the DC capacitors of the wind turbine converters to a 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; a second starting unit, used to start the communication of each of the energy storage wind turbines; The device transmits 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, 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 smaller 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 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 establishment of the AC voltage of the offshore wind power low-frequency AC transmission system at least when it is determined that the AC voltage of each of the energy storage wind turbines reaches the set AC voltage value.

[0014] According to another aspect of the present application, a computer-readable storage medium is provided, the computer-readable storage medium comprising a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute any one of the methods for establishing AC voltage in the offshore wind power low-frequency AC transmission system.

[0015] According to another aspect of the present 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 are configured to be executed by the one or more processors, and the one or more programs include a method for executing any one of the methods for establishing an AC voltage of an offshore wind power low-frequency AC transmission system.

[0016] By applying the technical solution of the present application, the energy storage device of each energy storage wind turbine is started, the DC capacitor of the wind turbine converter is charged to the first rated DC voltage, and the mechanical part and the machine-side converter of the energy storage wind turbine are unlocked, and the DC voltage of the wind turbine converter is controlled to be adjusted to the first rated DC voltage; the communication device of each energy storage wind turbine is started, and the actual value of the active power 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 converter of each energy storage wind turbine is started, and the AC voltage of each energy storage wind turbine is controlled to rise to the set AC voltage value, and at least when it is determined that the AC voltage of each energy storage wind turbine reaches the set AC voltage value, the AC voltage of the offshore wind power low-frequency AC transmission system is established. 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 that the existing technology does not consider the distribution of active power in the process of establishing AC voltage, resulting in active circulating current. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0018] Figure 1 A hardware structure block diagram of a mobile terminal for executing an AC voltage establishment method for an offshore wind power low-frequency AC transmission system provided in an embodiment of the present application is shown;

[0019] Figure 2 A schematic flow chart of a method for establishing AC voltage of an offshore wind power low-frequency AC transmission system provided in accordance with an embodiment of the present application is shown;

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

[0021] Figure 4 A schematic flow chart of a method for establishing AC voltage of a specific offshore wind power low-frequency AC transmission system provided in accordance with an embodiment of the present application is shown;

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

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

[0024] 102, processor; 104, memory; 106, transmission device; 108, input and output devices. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work 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 and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] As introduced in the background technology, the prior art does not consider the distribution of active power during the process of establishing AC voltage, and there is a problem of active circulating current. In order to solve the problem that the prior art does not consider the distribution of active power during the process of establishing AC voltage, and there is a problem of active circulating current, the embodiments of the present application provide an AC voltage establishment method, device, computer-readable storage medium and electronic device for an offshore wind power low-frequency AC transmission system.

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

[0030] The method embodiments provided in the embodiments of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking running on a mobile terminal as an example, Figure 1 1 is a hardware structure block diagram of a mobile terminal for establishing an AC voltage of an offshore wind power low-frequency AC transmission system according to an embodiment of the present invention. Figure 1 As shown, the mobile terminal may include one or more ( Figure 1Only one is shown in the figure) a processor 102 (the processor 102 may include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA) and a memory 104 for storing data, wherein the mobile terminal may also include a transmission device 106 and an input / output device 108 for communication functions. It can be understood by those skilled in the art that Figure 1 The structure shown is only for illustration and does not limit the structure of the mobile terminal. Figure 1 More or fewer components as shown, or with Figure 1 Different configurations are shown.

[0031] The memory 104 can be used to store computer programs, for example, software programs and modules of application software, such as the computer program corresponding to the AC voltage establishment method of the offshore wind power low-frequency AC transmission system in the embodiment of the present invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, to implement the above method. The memory 104 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include a memory remotely arranged relative to the processor 102, and these remote memories may be connected to the mobile terminal via a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof. The transmission device 106 is used to receive or send data via a network. The above-mentioned specific examples of the network may include a wireless network provided by a communication provider of the mobile terminal. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, referred to as NIC), which can be connected to other network devices through a base station so as 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] In this embodiment, a method for establishing AC voltage in an offshore wind power low-frequency AC transmission system running on a mobile terminal, a computer terminal or a similar computing device is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in an order different from that shown here.

[0033] Figure 21 is a flow chart of a method for establishing an AC voltage of an offshore wind power low-frequency AC transmission system according to an embodiment of the present application. The offshore wind power low-frequency AC transmission system includes a plurality of energy storage wind turbines and a DRU, such as Figure 3 As shown, the system also includes a wind turbine set, a collector line, an AC bus 1, a step-up transformer, an AC bus 2, a converter transformer, an MMC, a reactive power compensation device, an AC filter, and an AC system. The energy storage wind turbine includes an energy storage device, a wind turbine converter, a machine-side converter, a grid-side converter, and a communication device. Figure 2 As shown, the method comprises the following steps:

[0034] Step S201, 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 part of the energy storage wind turbine and the machine-side converter, and controlling 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 blades and bearings of the fan. Unlocking the mechanical part of the energy storage fan requires ensuring that the blades can rotate freely and that the bearings have no abnormal wear or jamming.

[0036] The machine-side converter is a device that converts the AC power generated by the wind turbine generator into DC power. Controlling the DC voltage of the wind turbine converter to the rated value can ensure the stability and safety of the system. The converter needs to be debugged and monitored to ensure that the DC voltage is within the normal range.

[0037] In general, unlocking the mechanical part and machine-side converter of the energy storage wind turbine is an important step to ensure the normal operation of the wind turbine and the safety and stability of the power generation system.

[0038] Step S202, starting the communication device of each of the energy storage wind turbines, and 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, 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 smaller 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 started, 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 above-mentioned 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 above-mentioned AC voltage of each of the above-mentioned energy storage wind turbines reaches the above-mentioned set AC voltage value, complete the establishment of the AC voltage of the above-mentioned offshore wind power low-frequency AC transmission system.

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

[0042] Through this embodiment, the energy storage device of each energy storage wind turbine is started, the DC capacitor of the wind turbine converter is charged to the first rated DC voltage, and the mechanical part and the machine-side converter of the energy storage wind turbine are unlocked, and the DC voltage of the wind turbine converter is controlled to be adjusted to the first rated DC voltage; the communication device of each energy storage wind turbine is started, and the actual value of the active power 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 converter of each energy storage wind turbine is started, and the AC voltage of each energy storage wind turbine is controlled to rise to the set AC voltage value, and at least when it is determined that the AC voltage of each energy storage wind turbine reaches 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 that the existing technology does not consider the distribution of active power in the process of establishing AC voltage, resulting in active circulating current.

[0043] In the specific implementation process, the grid-side converter of each of the above-mentioned energy storage wind turbines is started, and the AC voltage of each of the above-mentioned energy storage wind turbines is controlled to rise to a set AC voltage value, including: starting the grid-side converter of each of the above-mentioned energy storage wind turbines, respectively determining the first grid-connected point d-axis voltage of each of the above-mentioned energy storage wind turbines, wherein the first grid-connected point d-axis voltage is the voltage before conduction; controlling the grid-connected point d-axis voltage of each of the above-mentioned energy storage wind turbines to be boosted to the first grid-connected point d-axis voltage; determining the second grid-connected point d-axis voltage of each of the above-mentioned energy storage wind turbines, and controlling each of the above-mentioned energy storage wind turbines to rise from the first grid-connected point d-axis voltage to the second grid-connected point d-axis voltage, wherein the second grid-connected point d-axis voltage is the set AC voltage value.

[0044] Specifically, respectively determining the d-axis voltage of the first grid connection point of each of the above energy storage wind turbines includes: 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 except for the energy storage wind turbine closest to the DRU Among them, v u is the rate of increase of the AC voltage amplitude, t is the time, k iis the integral parameter of the active power controller, s is the Laplace operator, P j (j=2,3,…,n) is the actual value of active power of this energy storage wind turbine and P k (k=1, 2, ..., n-1) is the third energy storage wind fan, the third energy storage wind fan is adjacent to the current energy storage wind fan, and the distance between the third energy storage wind fan and the DRU is smaller than the distance between the current energy storage wind fan and the DRU.

[0045] More specifically, determining the d-axis voltage of the second grid connection point of each of the above energy storage wind turbines includes: according to the third formula: Determine the d-axis voltage of the second grid connection point of each of the energy storage wind turbines Among them, u fdi0 is the d-axis voltage of the first grid-connected point of each of the energy storage wind turbines, P i * and P i is the active power reference value and actual active power value of the above energy storage wind turbine, k p is the proportional parameter of the active power controller, and s is the Laplace operator.

[0046] The method starts the grid-side converters of all energy storage wind turbines at the same time, controls the AC voltage amplitude of each of the above energy storage wind turbines to rise linearly, and 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, and set the q-axis voltage reference value of the grid connection point to 0;

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

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

[0049] Among them, v u is the rate of increase of the AC voltage amplitude, t is the time, k i is the integral parameter of the active power controller. j (j=2,3,…,n) and P k (k=1, 2, ..., n-1) is the actual value of the active power of the energy storage wind turbine and the actual value of the active power of the adjacent energy storage wind turbine.

[0050] During the AC voltage boosting process, the d-axis voltage reference value of 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 the adjacent energy storage wind turbine, and the active power of all energy storage wind turbines is the same, achieving an average distribution of active power.

[0051] Furthermore, after respectively 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 above 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 energy storage wind turbines, K G and K T are the proportional parameter and time parameter of the first-order inertial controller, Q i (i=1,2,…,n) is the actual value of reactive power of each of the above energy storage wind turbines, Q i * is the reactive power reference value of each of the above energy storage wind turbines, and s is the Laplace operator; the voltage frequency of each of the above energy storage wind turbines is controlled to reach the above target voltage frequency.

[0052] This method also needs to calculate the voltage frequency of each energy storage fan so that the voltage frequency of each energy storage fan is the same. Controlling the AC voltage frequency of each energy storage fan to be the same can ensure the coordinated operation of each fan in the system. When the voltage frequency of each energy storage fan is the same, equipment damage or grid instability caused by voltage instability or inconsistent frequency can be avoided. In addition, synchronized voltage frequency also helps to achieve energy complementarity and energy balance between fans, and improve the overall efficiency and stability of the system. Therefore, controlling the AC voltage frequency of each energy storage fan to be the same is an important measure to ensure the normal operation of the system and improve the overall performance.

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

[0054] Specifically, 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 above active power target value P i1 , where V dcDRU is the DC voltage rating of the above DRU, U g is the voltage amplitude that needs to be reached at the AC bus near the above DRU, T DRU and X Tare respectively the transformation ratio and leakage reactance of the above-mentioned DRU converter, and n is the number of the above-mentioned energy storage wind turbines.

[0055] This method calculates the active power P that the energy storage fan needs to generate based on the voltage amplitude Ug that needs to be reached at the AC bus. i1 When the energy storage fan generates active power P i1 When the AC voltage amplitude of the AC bus reaches Ug, it is confirmed that the requirements for establishing AC voltage are met.

[0056] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the method for establishing AC voltage of the offshore wind power low-frequency AC transmission system of the present application will be described in detail below in combination with specific embodiments.

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

[0058] (1) Starting the energy storage device of the energy storage fan to charge the DC capacitor of the fan converter of the energy storage fan to the rated DC voltage.

[0059] (2) Unlock the mechanical part and 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) The communication devices of all energy storage wind turbines are started, 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.

[0061] (4) Start the grid-side converters of all energy storage wind turbines at the same time, control the AC voltage amplitude to rise linearly, and 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-connected point, and set the q-axis voltage reference value at the grid-connected point to 0. The frequency reference value of the grid-side converter of the energy storage wind turbine is:

[0062]

[0063] Among them, ω0 is the initial value of the voltage frequency, K G and K T are the proportional parameter and time parameter of the first-order inertial controller, Q i (i=1,2,…,n) is the actual value of reactive power of the energy storage fan, Q i * It is the reactive power reference value of the energy storage wind turbine.

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

[0065] Among them, v u is the rate of increase of the AC voltage amplitude, and t is the time.

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

[0067]

[0068] Among them, v u is the rate of increase of the AC voltage amplitude, t is the time, k i is the integral parameter of the active power controller. j (j=2,3,…,n) and P k (k=1, 2, ..., n-1) is the actual value of the active power of the energy storage wind turbine and the actual value of the active power of the adjacent energy storage wind turbine.

[0069] During the AC voltage boosting process, the d-axis voltage reference value of 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 the adjacent energy storage wind turbine, and the active power of all energy storage wind turbines is the same, achieving an average distribution of active power.

[0070] (5) After time t u After that, the energy storage fan records the grid connection point d-axis voltage reference value u fdi0 And the actual value of active power P i0 , calculate the second reference value of the d-axis voltage at the grid connection point, linearly increase the active power generated by the energy storage wind turbine, and make the voltage of the offshore wind farm close to the 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 is time t u The reference value of the d-axis voltage at the grid connection point of the energy storage wind turbine, P i * and P i is the active power reference value and actual active power value of the energy storage fan; k p is the proportional parameter of the active power controller. In 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 is the DRU DC voltage rating, Ug Yes Figure 3 The voltage amplitude required at the AC bus 2 is shown as T DRU and X T are the transformation ratio and leakage reactance of the DRU converter, and n is the number of energy storage fans. In this way, the active power generated by the energy storage fans is controlled to P i1 , the AC voltage amplitude at AC bus 2 reaches U g , the AC voltage is established.

[0075] This embodiment establishes the AC voltage of the low-frequency system by using a small number of wind turbines equipped with 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 voltage amplitude at the grid connection point, and the difference in active power between adjacent energy storage wind turbines is eliminated to achieve an even distribution of active power. The active power that the energy storage wind turbine needs to emit is calculated based on the required AC voltage amplitude, and the AC voltage amplitude is controlled to meet the voltage building requirement by controlling the active power emitted by the energy storage wind turbine.

[0076] The embodiment of the present application also provides an AC voltage establishing device for an offshore wind power low-frequency AC transmission system. It should be noted that the AC voltage establishing device for an offshore wind power low-frequency AC transmission system in the embodiment of the present application can be used to execute the AC voltage establishing method for an offshore wind power low-frequency AC transmission system provided in the embodiment of the present application. The device is used to implement the above-mentioned embodiments and preferred implementation modes, and those that have been described will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware for a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0077] The following introduces the AC voltage establishing device of the offshore wind power low-frequency AC transmission system provided in the embodiment of the present application.

[0078] Figure 5 Schematic diagram of an AC voltage establishment device of an offshore wind power low-frequency AC transmission system according to an embodiment of the present application. 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, machine-side converters, grid-side converters, and communication devices, such as Figure 5 As shown, the device comprises:

[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 above-mentioned wind turbine converter to the first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the above-mentioned machine-side converter, and control the DC voltage of the above-mentioned wind turbine converter to be adjusted to the above-mentioned first rated DC voltage;

[0080] The second starting unit 52 is used to start the communication device of each of the 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, 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 smaller 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 complete the establishment of the AC voltage of the above-mentioned offshore wind power low-frequency AC transmission system at least when it is determined that the AC voltage of each of the above-mentioned energy storage wind turbines reaches the set AC voltage value.

[0082] In this embodiment, a first starting unit is used to start the energy storage device of each of the above-mentioned energy storage wind turbines, charge the DC capacitor of the above-mentioned wind turbine converter to the first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the above-mentioned machine-side converter, and control the DC voltage of the above-mentioned wind turbine converter to be adjusted to the above-mentioned first rated DC voltage; a second starting unit is used to start the above-mentioned 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 above-mentioned energy storage wind turbine and the above-mentioned DRU, wherein the above-mentioned second energy storage wind turbine is adjacent to the above-mentioned first energy storage wind turbine, and the distance between the above-mentioned first energy storage wind turbine and the above-mentioned DRU is less than the distance between the above-mentioned second energy storage wind turbine and the above-mentioned DRU; a control unit is used to start the above-mentioned 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 the set AC voltage value, and at least when it is determined that the above-mentioned AC voltage of each of the above-mentioned energy storage wind turbines reaches the above-mentioned set AC voltage value, complete the establishment of the AC voltage of the above-mentioned 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 that the existing technology does not consider the distribution of active power in the process of establishing AC voltage, resulting in active circulating current.

[0083] As an optional scheme, the control unit includes a first determination module, a first control module and a second determination module; the first determination module is used to start the above-mentioned grid-side converter of each of the above-mentioned energy storage wind turbines, and respectively determine the first grid-connected point d-axis voltage of each of the above-mentioned energy storage wind turbines, wherein the above-mentioned first grid-connected point d-axis voltage is the voltage before conduction; the first control module is used to control the grid-connected point d-axis voltage of each of the above-mentioned energy storage wind turbines to be boosted to the above-mentioned first grid-connected point d-axis voltage; the second determination module is used to determine the second grid-connected 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 increase from the above-mentioned first grid-connected point d-axis voltage to the above-mentioned second grid-connected point d-axis voltage, wherein the above-mentioned second grid-connected point d-axis voltage is the above-mentioned set AC voltage value.

[0084] In an optional solution, the first determination module includes a first determination submodule and a second determination submodule; the first determination 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 DRU The second determination submodule is used to determine the following formula: Determine the d-axis voltage of the first grid connection point except for the energy storage wind turbine closest to the DRU Among them, v u is the rate of increase of the AC voltage amplitude, t is the time, k i is the integral parameter of the active power controller, s is the Laplace operator, P j (j=2,3,…,n) is the actual value of active power of this energy storage wind turbine and P k (k=1, 2, ..., n-1) is the third energy storage wind fan, the third energy storage wind fan is adjacent to the current energy storage wind fan, and the distance between the third energy storage wind fan and the DRU is smaller than the distance between the current energy storage wind fan and the DRU.

[0085] In an optional solution, the second determination module includes a third determination submodule, which is used to determine the value according to a third formula: Determine the d-axis voltage of the second grid connection point of each of the energy storage wind turbines Among them, u fdi0 is the d-axis voltage of the first grid-connected point of each of the energy storage wind turbines, P i * and P i is the active power reference value and actual active power value of the above energy storage wind turbine, k p is the proportional parameter of the active power controller, and s is the Laplace operator.

[0086] In an optional solution, the control unit further includes a third determination module and a second control module, and the third determination module is used to determine the d-axis voltage of the first grid connection point of each of the above-mentioned energy storage wind turbines respectively, 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 above 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 energy storage wind turbines, K G and K T are the proportional parameter and time parameter of the first-order inertial controller, Q i (i=1,2,…,n) is the actual value of reactive power of each of the above energy storage wind turbines, Q i * is the reactive power reference value of each of the above-mentioned 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 above-mentioned energy storage wind turbines to reach the above-mentioned target voltage frequency.

[0087] In an optional scheme, the control unit also includes a fourth determination module and a fifth determination module; the fourth determination module is used to determine whether the actual active power value of each of the above-mentioned energy storage wind turbines reaches the active power target value when it is determined that the above-mentioned AC voltage of each of the above-mentioned energy storage wind turbines reaches the above-mentioned set AC voltage value; the fifth determination module is used to complete the establishment of the AC voltage of the above-mentioned offshore wind power low-frequency AC transmission system when the actual active power value of each of the above-mentioned energy storage wind turbines reaches the above-mentioned active power target value.

[0088] In an optional solution, the control unit further includes a sixth determination module, which is used to determine whether the actual active power value of each of the above 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 is the DC voltage rating of the above DRU, U g is the voltage amplitude that needs to be reached at the AC bus near the above DRU, T DRU and X T are respectively the transformation ratio and leakage reactance of the above-mentioned DRU converter, and n is the number of the above-mentioned energy storage wind turbines.

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

[0090] The processor includes a kernel, which retrieves the corresponding program unit from the memory. One or more kernels can be set, and the kernel parameters can be adjusted to solve the problem that the existing technology does not consider the distribution of active power during the establishment of AC voltage, and there is active circulating current.

[0091] The memory may include non-permanent memory in a computer-readable medium, 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] An embodiment of the present invention provides a computer-readable storage medium, which includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute the AC voltage establishment method of the offshore wind power low-frequency AC transmission system.

[0093] Specifically, the method for establishing the AC voltage of the offshore wind power low-frequency AC transmission system includes:

[0094] Step S201, 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 part of the energy storage wind turbine and the machine-side converter, and controlling the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage;

[0095] Step S202, starting the communication device of each of the energy storage wind turbines, and 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, 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 smaller than the distance between the second energy storage wind turbine and the DRU;

[0096] Step S203, after the transmission is completed, start the above-mentioned 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 above-mentioned AC voltage of each of the above-mentioned energy storage wind turbines reaches the above-mentioned set AC voltage value, complete the establishment of the AC voltage of the above-mentioned offshore wind power low-frequency AC transmission system.

[0097] An embodiment of the present invention provides a processor, which is used to run a program, wherein the program, when running, executes the method for establishing AC voltage of the offshore wind power low-frequency AC transmission system.

[0098] Specifically, the method for establishing the AC voltage of the offshore wind power low-frequency AC transmission system includes:

[0099] Step S201, 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 part of the energy storage wind turbine and the machine-side converter, and controlling the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage;

[0100] Step S202, starting the communication device of each of the energy storage wind turbines, and 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, 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 smaller than the distance between the second energy storage wind turbine and the DRU;

[0101] Step S203, after the transmission is completed, start the above-mentioned 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 above-mentioned AC voltage of each of the above-mentioned energy storage wind turbines reaches the above-mentioned set AC voltage value, complete the establishment of the AC voltage of the above-mentioned offshore wind power low-frequency AC transmission system.

[0102] An embodiment of the present invention provides an electronic device, the device comprising a processor, a memory, and a program stored in the memory and executable on the processor, and when the processor executes the program, at least the following steps are implemented:

[0103] Step S201, 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 part of the energy storage wind turbine and the machine-side converter, and controlling the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage;

[0104] Step S202, starting the communication device of each of the energy storage wind turbines, and 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, 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 smaller than the distance between the second energy storage wind turbine and the DRU;

[0105] Step S203, after the transmission is completed, start the above-mentioned 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 above-mentioned AC voltage of each of the above-mentioned energy storage wind turbines reaches the above-mentioned set AC voltage value, complete the establishment of the AC voltage of the above-mentioned offshore wind power low-frequency AC transmission system.

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

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

[0108] Step S201, 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 part of the energy storage wind turbine and the machine-side converter, and controlling the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage;

[0109] Step S202, starting the communication device of each of the energy storage wind turbines, and 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, 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 smaller than the distance between the second energy storage wind turbine and the DRU;

[0110] Step S203, after the transmission is completed, start the above-mentioned 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 above-mentioned AC voltage of each of the above-mentioned energy storage wind turbines reaches the above-mentioned set AC voltage value, complete the establishment of the AC voltage of the above-mentioned offshore wind power low-frequency AC transmission system.

[0111] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0112] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0113] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0114] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0115] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions 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] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0118] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules 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 technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0119] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0120] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0121] 1) A method for establishing AC voltage of an offshore wind power low-frequency AC transmission system of the present 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, machine-side converters, grid-side converters, and communication devices, the method includes: starting the energy storage devices of each of the energy storage wind turbines, charging the DC capacitors of the wind turbine converters to a first rated DC voltage, unlocking the mechanical part of the energy storage wind turbine and the machine-side converter, controlling the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage; starting the communication devices of each of the energy storage wind turbines, and charging the DC capacitors of the wind turbine converters to a first rated DC voltage according to the energy storage devices; The distance relationship between the wind turbine and the above-mentioned DRU is used to transmit the actual value of the active power of the first energy storage wind turbine to the second energy storage wind turbine, wherein the above-mentioned second energy storage wind turbine is adjacent to the above-mentioned first energy storage wind turbine, and the distance between the above-mentioned first energy storage wind turbine and the above-mentioned DRU is less than the distance between the above-mentioned second energy storage wind turbine and the above-mentioned DRU; after the transmission is completed, the above-mentioned grid-side converter of each of the above-mentioned energy storage wind turbines is started, and the AC voltage of each of the above-mentioned energy storage wind turbines is controlled to rise to the set AC voltage value, and at least when it is determined that the above-mentioned AC voltage of each of the above-mentioned energy storage wind turbines reaches the above-mentioned set AC voltage value, the AC voltage of the above-mentioned offshore wind power low-frequency AC transmission system is established. 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, and the active power is evenly distributed, which solves the problem that the existing technology does not consider the distribution of active power in the process of establishing AC voltage and there is active circulation.

[0122] 2) An AC voltage establishing device for an offshore wind power low-frequency AC transmission system of the present 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, machine-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 above energy storage wind turbines, charge the DC capacitors of the above wind turbine converters to a first rated DC voltage, unlock the mechanical part of the energy storage wind turbine and the above machine-side converter, and control the DC voltage of the above wind turbine converter to be adjusted to the above first rated DC voltage; a second starting unit, used to start the above communication devices of each of the above energy storage wind turbines, According to the distance relationship between the energy storage wind turbine and the DRU, the actual value of the active power 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; the control unit is used to start the grid-side converter of each energy storage wind turbine after the transmission is completed, control the AC voltage of each energy storage wind turbine to rise to the set AC voltage value, and complete the establishment of the AC voltage of the offshore wind power low-frequency AC transmission system at least when it is determined that the AC voltage of each energy storage wind turbine reaches the set AC voltage value. 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, and the average distribution of active power is achieved, which solves the problem that the existing technology does not consider the distribution of active power in the process of establishing AC voltage and there is active circulation.

[0123] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for establishing AC voltage 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 DRUs, wherein the energy storage wind turbines include energy storage devices, wind turbine converters, machine-side converters, grid-side converters, and communication devices, and the method includes: 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 part of the energy storage wind turbine and the machine-side converter, and controlling the DC voltage of the wind turbine converter to be adjusted to the first rated DC voltage; Starting the communication device of each of the energy storage wind turbines, and 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, 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 of the energy storage wind turbines is started, and the AC voltage of each of the energy storage wind turbines is controlled to rise to a set AC voltage value. At least when it is determined that the AC voltage of each of the energy storage wind turbines reaches the set AC voltage value, the AC voltage establishment of the offshore wind power low-frequency AC transmission system is completed.

2. The method according to claim 1, characterized in that 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, including: Starting the grid-side converter of each of the energy storage wind turbines, and respectively determining the first grid-connected point d-axis voltage of each of the energy storage wind turbines, wherein the first grid-connected point d-axis voltage is the voltage before conduction; Controlling the grid-connected point d-axis voltage of each energy storage wind turbine to be boosted to the first grid-connected point d-axis voltage; Determine the second grid-connected point d-axis voltage of each of the energy storage wind turbines, and control each of the energy storage wind turbines to increase from the first grid-connected point d-axis voltage to the second grid-connected point d-axis voltage, wherein the second grid-connected point d-axis voltage is the set AC voltage value.

3. The method according to claim 2, characterized in that Respectively determining the d-axis voltage of the first grid connection point of each of the energy storage wind turbines, 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 except the energy storage wind turbine closest to the DRU Among them, v u is the rate of increase of the AC voltage amplitude, t is the time, k i is the integral parameter of the active power controller, s is the Laplace operator, P j (j=2,3,…,n) is the actual value of 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 current energy storage wind turbine, and the distance between the third energy storage wind turbine and the DRU is smaller than the distance between the current energy storage wind turbine and the DRU.

4. The method according to claim 2, characterized in that: Determining the d-axis voltage of the second grid connection point of each of the energy storage wind turbines comprises: According to the third formula: Determine the d-axis voltage of the second grid connection point of each of the energy storage wind turbines Among them, u fdi0 is the d-axis voltage of the first grid-connected point of each of the energy storage wind turbines, P i * and P i is the active power reference value and the actual active power 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 according to claim 2, characterized in that: After respectively determining the d-axis voltage of the first grid-connected 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 energy storage wind turbine 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, K G and K T are the proportional parameter and time parameter of the first-order inertial controller, Q i (i=1,2,…,n) is the actual value of reactive power of each energy storage fan, Q i * is the reactive power reference value of each of the energy storage wind turbines, and s is the Laplace operator; The voltage frequency of each of the energy storage fans is controlled to reach the target voltage frequency.

6. The method according to claim 1, characterized in that At least when it is determined that the AC voltage of each of the energy storage wind turbines reaches the set AC voltage value, the AC voltage of the offshore wind power low-frequency AC transmission system is established, including: In the case where it is determined that the AC voltage of each of the energy storage fans reaches the set AC voltage value, determining whether the actual active power value of each of the energy storage fans reaches the active power target value; When the actual active power value of each of the energy storage wind turbines reaches the active power target value, the establishment of the AC voltage of the offshore wind power low-frequency AC transmission system is completed.

7. The method according to claim 6, characterized in that 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 active power target value P i1 , where V dcDRU is the DC voltage rating of the DRU, U g is the voltage amplitude that needs to be reached at the AC bus near the DRU, T DRU and X T are respectively the transformation ratio and leakage reactance of the DRU converter, and n is the number of the energy storage wind turbines.

8. An AC voltage establishing device for an offshore wind power low-frequency AC transmission system, characterized in that: 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, machine-side converters, grid-side converters, and communication devices. The devices include: A first starting unit, used 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, 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; A second starting unit is used to start the communication device of each of the 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, 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 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 establishment of the AC voltage of the offshore wind power low-frequency AC transmission system at least when it is determined that the AC voltage of each of the energy storage wind turbines reaches the set AC voltage value.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute the method for establishing AC voltage of the offshore wind power low-frequency AC transmission system as described in any one of claims 1 to 7.

10. An electronic device, characterized in that: include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include a method for establishing an AC voltage of an offshore wind power low-frequency AC transmission system as described in any one of claims 1 to 7.

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