CN108631358A - Method and apparatus are determined based on the directly driven wind-powered unit impedance of control hardware in loop - Google Patents

Abstract

The invention provides a method and device for determining the impedance of a direct-drive wind turbine based on control hardware in the loop. First, the total delay of the simulation interface is calculated, and then the current signal of the pre-built direct-drive wind turbine grid-side converter is transmitted with delay The positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine are determined by the function and the delay transfer function of the voltage signal. The positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine are obtained with high precision and simple implementation process. The method for determining the impedance of a direct-drive wind turbine in the present invention can provide a theoretical basis for the correction of subsequent impedance scanning results; compared with the offline simulation method, it can not only inherit the flexible and convenient characteristics of simulation model scanning, but also overcome the fact that the offline model ignores the real controller, etc. Compared with the actual measurement of impedance, it can not only inherit the control characteristics of the real device, but also reduce the difficulty of implementing high-power linear amplifier technology, and also greatly reduce the cost of construction.

Description

Method and device for determining impedance of direct drive wind turbine based on control hardware in the loop

technical field

The invention relates to the field of new energy grid-connected oscillation technology, in particular to a method and device for determining the impedance of a direct-drive wind turbine based on control hardware in the loop.

Background technique

At present, in the face of increasingly serious global problems such as energy shortage, environmental pollution and climate warming, large-scale development and utilization of renewable energy such as wind and light has become an important choice for energy strategies of countries around the world. However, with the sharp increase in the proportion of renewable energy installed capacity and the gradual weakening of access to the synchronous grid, the stability characteristics of the power system are undergoing profound changes. Safe and stable operation of the power grid.

The United States, China, and many European countries have carried out preliminary research work on practical problems such as sub/supersynchronous oscillation and harmonic oscillation in their own countries. Among them, the large-scale new energy grid-connected stability analysis and oscillation suppression method based on impedance theory It has gradually been recognized as an effective method by the industry and has become a research hotspot in the academic circle. In the process of using impedance theory to analyze the oscillation mechanism and formulate solutions, how to accurately obtain the impedance characteristics of new energy grid-connected devices has become one of the key factors for the successful application of this method.

At present, the ways to obtain the impedance of direct-drive wind turbines mainly include the following: 1) The small-signal impedance modeling method based on harmonic linearization, which is based on the detailed main circuit structure, control block diagram and parameters of the grid-connected device. However, in actual engineering, the above data sources have become the main constraints restricting impedance modeling; 2) The offline simulation model of the grid-connected device is scanned to obtain impedance characteristics, but compared with the actual device, the simulation model has simplifications in signal conditioning, sampling and holding, etc. At the same time, the control parameters need to be converted in multiple steps in the actual controller, resulting in low impedance accuracy of the obtained direct-drive wind turbine; 3) The active injection method is adopted, that is, the harmonics of different frequencies are superimposed on the fundamental wave component of the normal grid voltage The voltage disturbance component is detected and recorded in real time due to the influence data of the frequency harmonic component on the grid-connected voltage and current. Finally, through the FFT analysis of the voltage and current data, the impedance characteristics under different frequency responses are calculated. This method is based on the disturbance The measurement method of the injection device can obtain the impedance of the direct-drive wind turbine, but the implementation process is difficult and the cost is high. This method is still in the research stage of low-power laboratories.

Contents of the invention

Aiming at the current direct-drive wind turbines currently in operation on site, in order to overcome the problems of low impedance accuracy, difficult implementation process and high cost of the direct-drive wind turbines in the prior art, the present invention provides a direct-drive wind turbine based on control hardware in the loop. The method and device for determining unit impedance firstly calculate the total delay of the simulation interface according to the control cycle of the direct-drive wind turbine grid-side converter, and then according to the pre-built current signal delay transfer function of the direct-drive wind turbine grid-side converter and The voltage signal delay transfer function determines the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine; the current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter are determined according to the total delay of the simulation interface , the final positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine have high precision, the realization process is simple, and the cost is low.

In order to realize the above-mentioned purpose of the invention, the present invention takes the following technical solutions:

On the one hand, the present invention provides a method for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop, including:

Calculate the total delay of the simulation interface according to the control cycle of the direct-drive wind turbine grid-side converter;

Determine the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine according to the pre-built current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter;

The current signal delay transfer function and the voltage signal delay transfer function of the grid-side converter of the direct drive wind turbine are determined according to the total delay of the simulation interface.

According to the control period of the grid-side converter of the direct-drive wind turbine, the total delay of the simulation interface is calculated according to the following formula:

T _d =T _d1 +T _d2

Among them, T _d represents the total delay of the simulation interface, T _d1 represents the control cycle of the direct-drive wind turbine grid-side converter, and T _d2 represents the hardware interface delay of the real-time simulator.

The current signal delay transfer function and the voltage signal delay transfer function of the grid-side converter of the direct drive wind turbine are determined by the following formula:

Among them, G _i (s) represents the current signal delay transfer function of the direct-drive wind turbine grid-side converter; G _v (s) represents the voltage signal delay transfer function of the direct-drive wind turbine grid-side converter; T _d Indicates the total delay of the simulation interface; s indicates the Laplacian operator, and satisfies T _s represents the simulation step size of control hardware in the loop; ω _d represents the cutoff angular frequency of current signal conditioning, and ω _d =2·π·f _d , f _d represents the current signal conditioning cutoff frequency.

According to the current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter, the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine are determined as follows:

Among them, Z _p (s) represents the positive-sequence impedance of the direct-drive wind turbine, Z _n (s) represents the negative-sequence impedance of the direct-drive wind turbine, L represents the equivalent filter inductance of the grid-side converter of the direct-drive wind turbine, V _dc is the DC bus voltage of the grid-side converter of the direct-drive wind turbine, I ₁ is the grid-connected fundamental current amplitude of the grid-side converter of the direct-drive wind turbine, V ₁ is the grid-side converter of the direct-drive wind turbine Grid-connected fundamental wave voltage amplitude, φ _i1 represents the grid-connected power factor angle of the direct-drive wind turbine grid-side converter, ω ₁ represents the fundamental wave angular frequency of the direct-drive wind turbine grid-side converter, K _f represents the direct-drive wind turbine grid-side converter Feedforward coefficient of wind turbine grid-side converter;

T _PLL (s-jω ₁ ) and T _PLL (s+jω ₁ ) represent the closed-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and H _PLL (s-jω ₁ ) and H _PLL (s+jω ₁ ) represent the open-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and have k _pt represents the proportional coefficient of the phase-locked loop controller, and k _it represents the integral coefficient of the phase-locked loop controller;

H _i (s) represents the current controller transfer function of the grid-side converter of the direct drive wind turbine, and k _pi represents the proportional coefficient of the current controller, and k _ii represents the integral coefficient of the current controller.

On the other hand, the present invention also provides a direct drive wind turbine impedance determination device based on control hardware in the loop, including:

The calculation module is used to calculate the total delay of the simulation interface according to the control cycle of the grid-side converter of the direct-drive wind turbine;

The first determining module is used to determine the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine according to the pre-built current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter;

The current signal delay transfer function and the voltage signal delay transfer function of the grid-side converter of the direct drive wind turbine are determined according to the total delay of the simulation interface.

The calculation module is specifically used for:

According to the control period of the grid-side converter of the direct-drive wind turbine, the total delay of the simulation interface is calculated according to the following formula:

T _d =T _d1 +T _d2

Among them, T _d represents the total delay of the simulation interface, T _d1 represents the control cycle of the direct-drive wind turbine grid-side converter, and T _d2 represents the hardware interface delay of the real-time simulator.

The device also includes a second determination module, the second determination module is specifically used for:

According to the total delay of the simulation interface, the delay transfer function of the current signal and the delay transfer function of the voltage signal of the grid-side converter of the direct drive wind turbine are determined as follows:

Among them, G _i (s) represents the delay transfer function of the current signal of the grid-side converter of the direct-drive wind turbine; G _v (s) represents the delay transfer function of the voltage signal of the grid-side converter of the direct-drive wind turbine; s represents Laplacian, and satisfy T _s represents the simulation step size of control hardware in the loop; ω _d represents the cutoff angular frequency of current signal conditioning, and ω _d =2·π·f _d , f _d represents the current signal conditioning cutoff frequency.

The first determining module is specifically used for:

According to the current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter, the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine are determined as follows:

Among them, Z _p (s) represents the positive-sequence impedance of the direct-drive wind turbine, Z _n (s) represents the negative-sequence impedance of the direct-drive wind turbine, L represents the equivalent filter inductance of the grid-side converter of the direct-drive wind turbine, V _dc is the DC bus voltage of the grid-side converter of the direct-drive wind turbine, I ₁ is the grid-connected fundamental current amplitude of the grid-side converter of the direct-drive wind turbine, V ₁ is the grid-side converter of the direct-drive wind turbine Grid-connected fundamental wave voltage amplitude, φ _i1 represents the grid-connected power factor angle of the direct-drive wind turbine grid-side converter, ω ₁ represents the fundamental wave angular frequency of the direct-drive wind turbine grid-side converter, K _f represents the direct-drive wind turbine grid-side converter Feedforward coefficient of wind turbine grid-side converter;

T _PLL (s-jω ₁ ) and T _PLL (s+jω ₁ ) represent the closed-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and H _PLL (s-jω ₁ ) and H _PLL (s+jω ₁ ) represent the open-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and have k _pt represents the proportional coefficient of the phase-locked loop controller, and k _it represents the integral coefficient of the phase-locked loop controller;

H _i (s) represents the current controller transfer function of the grid-side converter of the direct drive wind turbine, and k _pi represents the proportional coefficient of the current controller, and k _ii represents the integral coefficient of the current controller.

Compared with the closest prior art, the technical solution provided by the present invention has the following beneficial effects:

In the method for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop provided by the present invention, the total delay of the simulation interface is first calculated according to the control period of the grid-side converter of the direct-drive wind turbine, and then the total delay of the simulation interface is calculated according to the pre-built direct-drive wind turbine network The current signal delay transfer function and voltage signal delay transfer function of the side converter determine the positive sequence impedance and negative sequence impedance of the direct drive wind turbine; the current signal delay transfer function and voltage The signal delay transfer function is determined according to the total delay of the simulation interface, and the finally obtained positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine have high precision, simple implementation process, and low cost;

The device for determining the impedance of a direct-drive wind turbine based on control hardware in the loop provided by the present invention includes a calculation module and a first determination module. The calculation module is used to calculate the total delay of the simulation interface according to the control period of the grid-side converter of the direct-drive wind turbine, The first determination module is used to determine the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine according to the pre-built current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter. The current signal delay transfer function and voltage signal delay transfer function of the grid-side converter of the unit are determined according to the total delay of the simulation interface, and the obtained positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine have high precision, and the implementation process is simple. low cost;

The method for determining the impedance of a direct drive wind turbine based on control hardware in the present invention can realize the embedding of a real controller in the simulation object, which not only retains the interface characteristics such as signal filtering, conditioning, and delay, but also reflects the source code operation control characteristics, and is based on The impedance determination method of the control hardware-in-the-loop direct-drive wind turbine does not require the control block diagram and control parameters involved in the controller, and treats the controller as a "gray box". It only needs to clarify the external interface of the controller, and it is between the impedance scanning of the offline simulation model An effective way between the actual measurement of the impedance of the disturbance injection device and the disturbance injection device;

The method for determining the impedance of the direct drive wind turbine based on the control hardware in the loop of the present invention can provide a theoretical basis for the correction of the subsequent impedance scanning results;

Compared with the offline simulation method, the technical solution provided by the present invention can not only inherit the flexible and convenient characteristics of simulation model scanning, but also overcome the fact that the offline model ignores the equivalent error of the real controller; compared with the actual impedance measurement, it can inherit the real device The control feature can reduce the difficulty of realizing the high-power linear amplifier technology, and also greatly reduce the manufacturing cost.

Description of drawings

Fig. 1 is a flowchart of a method for determining impedance of a direct-drive wind turbine based on control hardware-in-the-loop in an embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

The control-hardware-in-the-loop (CHIL) model of the direct drive wind turbine includes the following parts:

Real-time simulation platform: including CPU and FPGA; The computing step size of FPGA real-time simulation platform wherein is ns level, is mainly responsible for the small step size real-time solution of model, adopts OP5607 simulation platform in the embodiment of the present invention. The calculation step of the CPU real-time platform is 10-100us, and it is used as the communication interface between the upper computer and the FPGA platform and real-time data storage. The OP5600 simulation platform is used in the embodiment of the present invention. The communication between the CPU and the FPGA adopts the high-speed PCIe protocol, and the common TCP/IP protocol is used with the host computer.

Controller: It is the controller of the direct-drive wind turbine that actually operates on site. Based on the above-mentioned CHIL modeling and simulation principles, in order to realize the CHIL real-time simulation of the wind turbine, the following two aspects of information are needed: on the one hand, the main circuit topology information of the wind turbine , and the other hand is the interface information of the wind turbine controller.

The main circuit topology information is the information required for simulation modeling, so as to prepare and simulate the fan object in real-time simulation, and the interface information is the information for the interaction between the object in the simulation device and the actual controller, including voltage, Current, status of switches, and PWM control information.

Since the calculation of the impedance of the direct-drive wind turbine in the control hardware-in-the-loop environment will produce errors, the specific flow chart of the method for determining the impedance of the direct-drive wind turbine based on the control hardware-in-the-loop provided by the embodiment of the present invention is shown in Figure 1, and the specific process is as follows :

S101: Calculate the total delay of the simulation interface according to the control period of the grid-side converter of the direct-drive wind turbine;

S102: Determine the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine according to the pre-built current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter;

The current signal delay transfer function and the voltage signal delay transfer function of the grid-side converter of the direct drive wind turbine are determined according to the total delay of the simulation interface.

In the above S101, the total delay of the simulation interface is calculated according to the control cycle of the grid-side converter of the direct-drive wind turbine according to the following formula:

T _d =T _d1 +T _d2

Among them, T _d represents the total delay of the simulation interface, T _d1 represents the control cycle of the direct-drive wind turbine grid-side converter, and T _d2 represents the hardware interface delay of the real-time simulator.

In the above S102, the delay transfer function of the current signal and the delay transfer function of the voltage signal of the grid-side converter of the direct drive wind turbine are determined by the following formula:

Among them, G _i (s) represents the delay transfer function of the current signal of the grid-side converter of the direct-drive wind turbine; G _v (s) represents the delay transfer function of the voltage signal of the grid-side converter of the direct-drive wind turbine; s represents Laplacian, and satisfy T _s represents the simulation step size of control hardware in the loop; ω _d represents the cutoff angular frequency of current signal conditioning, and ω _d =2·π·f _d , f _d represents the current signal conditioning cutoff frequency.

In the above S103, according to the current signal delay transfer function and the voltage signal delay transfer function of the grid-side converter of the direct-drive wind turbine, and determine the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine according to the following formula:

Among them, Z _p (s) represents the positive-sequence impedance of the direct-drive wind turbine, Z _n (s) represents the negative-sequence impedance of the direct-drive wind turbine, L represents the equivalent filter inductance of the grid-side converter of the direct-drive wind turbine, V _dc is the DC bus voltage of the grid-side converter of the direct-drive wind turbine, I ₁ is the grid-connected fundamental current amplitude of the grid-side converter of the direct-drive wind turbine, V ₁ is the grid-side converter of the direct-drive wind turbine Grid-connected fundamental wave voltage amplitude, φ _i1 represents the grid-connected power factor angle of the direct-drive wind turbine grid-side converter, ω ₁ represents the fundamental wave angular frequency of the direct-drive wind turbine grid-side converter, K _f represents the direct-drive wind turbine grid-side converter Feedforward coefficient of wind turbine grid-side converter;

T _PLL (s-jω ₁ ) and T _PLL (s+jω ₁ ) represent the closed-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and H _PLL (s-jω ₁ ) and H _PLL (s+jω ₁ ) represent the open-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and have k _pt represents the proportional coefficient of the phase-locked loop controller, and k _it represents the integral coefficient of the phase-locked loop controller;

H _i (s) represents the current controller transfer function of the grid-side converter of the direct drive wind turbine, and k _pi represents the proportional coefficient of the current controller, and k _ii represents the integral coefficient of the current controller.

Based on the same inventive concept, the embodiment of the present invention also provides a direct-drive wind turbine impedance determination device based on control hardware in the loop, including a calculation module and a first determination module. The functions of the above modules are introduced below:

The calculation module is used to calculate the total delay of the simulation interface according to the control cycle of the direct-drive wind turbine grid-side converter;

The first determination module is used to determine the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine according to the pre-built current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter;

The delay transfer function of the current signal and the delay transfer function of the voltage signal of the grid-side converter of the direct drive wind turbine are determined according to the total delay of the simulation interface.

The above calculation module calculates the total delay of the simulation interface according to the control cycle of the grid-side converter of the direct-drive wind turbine as follows:

T _d =T _d1 +T _d2

Among them, T _d represents the total delay of the simulation interface, T _d1 represents the control cycle of the direct-drive wind turbine grid-side converter, and T _d2 represents the hardware interface delay of the real-time simulator.

The device also includes a second determination module, the second determination module is specifically used for:

According to the total delay of the simulation interface, the delay transfer function of the current signal and the delay transfer function of the voltage signal of the grid-side converter of the direct drive wind turbine are determined as follows:

Among them, G _i (s) represents the delay transfer function of the current signal of the grid-side converter of the direct-drive wind turbine; G _v (s) represents the delay transfer function of the voltage signal of the grid-side converter of the direct-drive wind turbine; s represents Laplacian, and satisfy T _s represents the simulation step size of control hardware in the loop; ω _d represents the cutoff angular frequency of current signal conditioning, and ω _d =2·π·f _d , f _d represents the current signal conditioning cutoff frequency.

The above-mentioned first determination module determines the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine according to the current signal delay transfer function and the voltage signal delay transfer function of the grid-side converter of the direct-drive wind turbine according to the following formula:

Among them, Z _p (s) represents the positive-sequence impedance of the direct-drive wind turbine, Z _n (s) represents the negative-sequence impedance of the direct-drive wind turbine, L represents the equivalent filter inductance of the grid-side converter of the direct-drive wind turbine, V _dc is the DC bus voltage of the grid-side converter of the direct-drive wind turbine, I ₁ is the grid-connected fundamental current amplitude of the grid-side converter of the direct-drive wind turbine, V ₁ is the grid-side converter of the direct-drive wind turbine Grid-connected fundamental wave voltage amplitude, φ _i1 represents the grid-connected power factor angle of the direct-drive wind turbine grid-side converter, ω ₁ represents the fundamental wave angular frequency of the direct-drive wind turbine grid-side converter, K _f represents the direct-drive wind turbine grid-side converter Feedforward coefficient of wind turbine grid-side converter;

T _PLL (s-jω ₁ ) and T _PLL (s+jω ₁ ) represent the closed-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and H _PLL (s-jω ₁ ) and H _PLL (s+jω ₁ ) represent the open-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and have k _pt represents the proportional coefficient of the phase-locked loop controller, and k _it represents the integral coefficient of the phase-locked loop controller;

H _i (s) represents the current controller transfer function of the grid-side converter of the direct drive wind turbine, and k _pi represents the proportional coefficient of the current controller, and k _ii represents the integral coefficient of the current controller.

For the convenience of description, each part of the device described above is divided into various modules or units by function and described separately. Of course, when implementing the present application, the functions of each module or unit can be implemented in one or more pieces of software or hardware.

Those skilled in the art should understand that the embodiments of the present application may be provided as methods, systems, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may 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.) having computer-usable program code embodied therein.

The present application is described with reference to flowcharts and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those of ordinary skill in the art can still modify or equivalently replace the specific implementation methods of the present invention with reference to the above embodiments. Any modifications or equivalent replacements departing from the spirit and scope of the present invention are within the protection scope of the claims of the pending application of the present invention.

Claims (8)

1. A method for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop, characterized in that it comprises: Calculate the total delay of the simulation interface according to the control cycle of the direct-drive wind turbine grid-side converter; Determine the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine according to the pre-built current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter; The current signal delay transfer function and the voltage signal delay transfer function of the grid-side converter of the direct drive wind turbine are determined according to the total delay of the simulation interface. 2. The method for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop according to claim 1, wherein the total delay of the simulation interface is calculated according to the following formula according to the control period of the grid-side converter of the direct-drive wind turbine Time: T _d =T _d1 +T _d2 Among them, T _d represents the total delay of the simulation interface, T _d1 represents the control cycle of the direct-drive wind turbine grid-side converter, and T _d2 represents the hardware interface delay of the real-time simulator. 3. The method for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop according to claim 1, wherein the current signal delay transfer function and the voltage signal delay of the grid-side converter of the direct-drive wind turbine are The transfer function is determined as follows: Among them, G _i (s) represents the current signal delay transfer function of the direct-drive wind turbine grid-side converter; G _v (s) represents the voltage signal delay transfer function of the direct-drive wind turbine grid-side converter; T _d Indicates the total delay of the simulation interface; s indicates the Laplacian operator, and satisfies T _s represents the simulation step size of control hardware in the loop; ω _d represents the cutoff angular frequency of current signal conditioning, and ω _d =2·π·f _d , f _d represents the current signal conditioning cutoff frequency. 4. The method for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop according to claim 3, wherein, according to the current signal delay transfer function and the voltage signal delay transfer of the grid-side converter of the direct-drive wind turbine function, and determine the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine as follows: Among them, Z _p (s) represents the positive-sequence impedance of the direct-drive wind turbine, Z _n (s) represents the negative-sequence impedance of the direct-drive wind turbine, L represents the equivalent filter inductance of the grid-side converter of the direct-drive wind turbine, V _dc is the DC bus voltage of the grid-side converter of the direct-drive wind turbine, I ₁ is the grid-connected fundamental current amplitude of the grid-side converter of the direct-drive wind turbine, V ₁ is the grid-side converter of the direct-drive wind turbine Grid-connected fundamental wave voltage amplitude, φ _i1 represents the grid-connected power factor angle of the direct-drive wind turbine grid-side converter, ω ₁ represents the fundamental wave angular frequency of the direct-drive wind turbine grid-side converter, K _f represents the direct-drive wind turbine grid-side converter Feedforward coefficient of wind turbine grid-side converter; T _PLL (s-jω ₁ ) and T _PLL (s+jω ₁ ) represent the closed-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and H _PLL (s-jω ₁ ) and H _PLL (s+jω ₁ ) represent the open-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and have k _pt represents the proportional coefficient of the phase-locked loop controller, and k _it represents the integral coefficient of the phase-locked loop controller; H _i (s) represents the current controller transfer function of the grid-side converter of the direct drive wind turbine, and k _pi represents the proportional coefficient of the current controller, and k _ii represents the integral coefficient of the current controller. 5. A device for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop, characterized in that it includes: The calculation module is used to calculate the total delay of the simulation interface according to the control cycle of the grid-side converter of the direct-drive wind turbine; The first determining module is used to determine the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine according to the pre-built current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter; The current signal delay transfer function and the voltage signal delay transfer function of the grid-side converter of the direct drive wind turbine are determined according to the total delay of the simulation interface. 6. The device for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop according to claim 5, wherein the calculation module is specifically used for: According to the control period of the grid-side converter of the direct-drive wind turbine, the total delay of the simulation interface is calculated according to the following formula: T _d =T _d1 +T _d2 Among them, T _d represents the total delay of the simulation interface, T _d1 represents the control cycle of the direct-drive wind turbine grid-side converter, and T _d2 represents the hardware interface delay of the real-time simulator. 7. The device for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop according to claim 5, wherein the device further comprises a second determination module, and the second determination module is specifically used for: According to the total delay of the simulation interface, the delay transfer function of the current signal and the delay transfer function of the voltage signal of the grid-side converter of the direct drive wind turbine are determined as follows: Among them, G _i (s) represents the current signal delay transfer function of the direct-drive wind turbine grid-side converter; G _v (s) represents the voltage signal delay transfer function of the direct-drive wind turbine grid-side converter; T _d Indicates the total delay of the simulation interface; s indicates the Laplacian operator, and satisfies T _s represents the simulation step size of control hardware in the loop; ω _d represents the cutoff angular frequency of current signal conditioning, and ω _d =2·π·f _d , f _d represents the current signal conditioning cutoff frequency. 8. The device for determining the impedance of a direct-drive wind turbine based on control hardware-in-the-loop according to claim 7, wherein the first determination module is specifically used for: According to the current signal delay transfer function and voltage signal delay transfer function of the direct-drive wind turbine grid-side converter, the positive-sequence impedance and negative-sequence impedance of the direct-drive wind turbine are determined as follows: Among them, Z _p (s) represents the positive-sequence impedance of the direct-drive wind turbine, Z _n (s) represents the negative-sequence impedance of the direct-drive wind turbine, L represents the equivalent filter inductance of the grid-side converter of the direct-drive wind turbine, V _dc is the DC bus voltage of the grid-side converter of the direct-drive wind turbine, I ₁ is the grid-connected fundamental current amplitude of the grid-side converter of the direct-drive wind turbine, V ₁ is the grid-side converter of the direct-drive wind turbine Grid-connected fundamental wave voltage amplitude, φ _i1 represents the grid-connected power factor angle of the direct-drive wind turbine grid-side converter, ω ₁ represents the fundamental wave angular frequency of the direct-drive wind turbine grid-side converter, K _f represents the direct-drive wind turbine grid-side converter Feedforward coefficient of wind turbine grid-side converter; T _PLL (s-jω ₁ ) and T _PLL (s+jω ₁ ) represent the closed-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and H _PLL (s-jω ₁ ) and H _PLL (s+jω ₁ ) represent the open-loop transfer function of the phase-locked loop controller of the direct-drive wind turbine grid-side converter, and have k _pt represents the proportional coefficient of the phase-locked loop controller, and k _it represents the integral coefficient of the phase-locked loop controller; H _i (s) represents the current controller transfer function of the grid-side converter of the direct drive wind turbine, and k _pi represents the proportional coefficient of the current controller, and k _ii represents the integral coefficient of the current controller.