Grid-forming device control method and apparatus, controller, device, and medium

Abstract

The present application relates to the technical field of wind power, and discloses a grid-forming device control method and apparatus, a controller, a device, and a medium. The method comprises: on the basis of an impedance from a grid side converter to a power grid, a preset inertia time constant and a preset angular velocity parameter, obtaining a damping coefficient of an active power synchronous loop by using a second-order system characteristic of the active power synchronous loop; on the basis of the damping coefficient, the inertia time constant and a control parameter of the active power synchronous loop, performing active power synchronization calculation, to obtain an internal potential phase of a grid-forming device; on the basis of a control parameter of a reactive power closed loop, performing reactive closed loop control calculation, to obtain an internal potential amplitude of the grid-forming device; and by using a PWM signal generated on the basis of the internal potential phase and the internal potential amplitude, controlling the grid side converter to operate.

Description

Control method and device of grid-forming equipment, controller, equipment and medium

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411354251.X, filed on September 26, 2024, entitled "Control method and device of grid-forming equipment, controller, equipment and medium", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application belongs to the field of wind power technology, and particularly relates to a control method, device, controller, equipment and medium of grid-forming equipment. BACKGROUND

[0004] With the development of clean energy technologies such as wind power generation technology and photovoltaic power generation technology, the proportion of clean energy equipment such as wind turbines and photovoltaic equipment in the power system is gradually increasing, making the power system including clean energy equipment and the grid have the trend of reduced inertia and weakened strength. In order to cope with power demand and environmental pressure, a grid-forming control strategy can be used to provide damping and inertia for the power system by using grid-forming equipment, which can quickly respond when the grid frequency changes and support the stability of the power system.

[0005] However, due to the differences in the structure of the power system, the grid strength in different regions of the power system is different, which can cause the active power response characteristics of the grid-forming equipment to be different under different grid strengths when the grid frequency changes, resulting in inconsistent support characteristics of the grid, thereby reducing the safety and reliability of the power system. SUMMARY

[0006] The embodiments of the present application provide a control method, device, controller and medium of grid-forming equipment, which can improve the safety and reliability of the power system.

[0007] The embodiments of the present application provide a control method of grid-forming equipment, the grid-forming equipment including a grid-side converter configured to be connected to a grid; the method includes: based on an impedance between the grid-side converter and the grid, a preset inertia time constant and a preset angular velocity parameter, obtaining a damping coefficient of an active power synchronization ring by using a second-order system characteristic of the active power synchronization ring; performing an operation according to the damping coefficient, the inertia time constant and a control parameter of the active power synchronization ring to obtain an internal electromotive force phase of the grid-forming equipment; performing a reactive power closed-loop control operation according to a control parameter of a reactive power ring to obtain an internal electromotive force amplitude of the grid-forming equipment; and controlling the grid-side converter to operate by using a PWM signal generated based on the internal electromotive force phase and the internal electromotive force amplitude.

[0008] In some possible embodiments, the damping coefficient of the active power synchronization loop is obtained based on an impedance between the grid-side converter and the power grid, a preset inertia time constant, and a preset angular velocity parameter, by using a second-order system characteristic of the active power synchronization loop, including: obtaining a target intermediate parameter according to the impedance between the grid-side converter and the power grid, the inertia time constant, the angular velocity parameter, and the second-order system characteristic; determining a target damping ratio corresponding to the target intermediate parameter in a pre-established damping corresponding relationship table, the damping corresponding relationship table including a corresponding relationship between the damping ratio and a value range of the intermediate parameter; and obtaining the damping coefficient according to the target damping ratio, the angular velocity parameter, the inertia time constant, the impedance between the grid-side converter and the power grid, and the second-order system characteristic.

[0009] In some possible embodiments, before determining the target damping ratio corresponding to the target intermediate parameter in the pre-established damping corresponding relationship, the method further includes: obtaining a plurality of different damping ratios, and calculating a value range of the intermediate parameter corresponding to the plurality of different damping ratios according to the second-order system characteristic and the plurality of different damping ratios; and establishing the damping corresponding relationship table according to the plurality of different damping ratios and the value range of the intermediate parameter corresponding to the plurality of different damping ratios.

[0010] In some possible embodiments, the determining the target damping ratio corresponding to the target intermediate parameter in the pre-established damping corresponding relationship table includes: determining a value range of the intermediate parameter into which the target intermediate parameter falls in the damping corresponding relationship table; and determining the damping ratio corresponding to the value range of the intermediate parameter into which the target intermediate parameter falls in the damping corresponding relationship table as the target damping ratio.

[0011] In some possible embodiments, the angular velocity parameter includes a cutoff angular velocity of the active power synchronization loop and a rated angular velocity of the power grid.

[0012] In some possible embodiments, the control parameter of the active power synchronization loop includes a measured active power of the grid-side converter, a reference active power of the grid-side converter, an internal electromotive force angular velocity, and a rated angular velocity of the power grid.

[0013] The active power synchronization operation is performed according to the damping coefficient, the inertia time constant, and the control parameter of the active power synchronization loop, to obtain an internal electromotive force phase of the grid-connected device, including: obtaining a torque increment of the grid-connected device according to a difference between the reference active power and the measured active power, and the internal electromotive force angular velocity; obtaining an angular velocity increment according to the torque increment, the inertia time constant, and the damping coefficient; and performing integral operation on a sum of the rated angular velocity and the angular velocity increment, to obtain the internal electromotive force phase.

[0014] In some possible embodiments, the control parameter of the reactive power loop includes a measured reactive power of the grid-side converter, a reference reactive power of the grid-side converter, and a rated voltage of the grid-connected device.

[0015] The reactive power closed-loop control operation is performed according to the control parameter of the reactive power loop to obtain the internal electromotive force amplitude of the grid-forming device, including: performing closed-loop control operation on the difference between the reference reactive power and the measured reactive power to obtain the voltage increment of the grid-forming device, the closed-loop control operation including at least one of proportional operation, integral operation and differential operation; and determining the sum of the voltage increment and the rated voltage as the internal electromotive force amplitude.

[0016] The embodiment of the present application further provides a control device of a grid-forming device, which is applied to the grid-forming device, and the grid-forming device includes a grid-side converter configured to be connected with a power grid; the device includes: a damping coefficient setting module configured to obtain a damping coefficient of an active power synchronization loop by using the second-order system characteristics of the active power synchronization loop based on the impedance between the grid-side converter and the power grid, a preset inertia time constant and a preset angular velocity parameter; a phase determining module configured to obtain an internal electromotive force phase of the grid-forming device by performing active power synchronization operation according to the damping coefficient, the inertia time constant and the control parameter of the active power synchronization loop; an amplitude determining module configured to obtain an internal electromotive force amplitude of the grid-forming device by performing reactive power closed-loop control operation according to the control parameter of the reactive power loop; and a control module configured to control the grid-side converter to operate by using a PWM signal generated based on the internal electromotive force phase and the internal electromotive force amplitude.

[0017] The embodiment of the present application further provides a controller of a grid-forming device, including a processor and a memory storing computer program instructions; the processor implements the control method of the grid-forming device in the embodiment of the present application when executing the computer program instructions.

[0018] The embodiment of the present application further provides a grid-forming device, including a grid-side converter, and an output end of the grid-side converter is configured to be connected with a power grid; a controller of the grid-forming device in the embodiment of the present application is connected with the grid-side converter.

[0019] The embodiment of the present application further provides a control method of a grid-forming device, the grid-forming device being connected with a power grid, and the method includes: obtaining an internal electromotive force phase of the grid-forming device matched with a power grid strength parameter, the power grid strength parameter being used to represent the strength of the power grid; obtaining an internal electromotive force amplitude of the grid-forming device; and controlling the grid-forming device based on the internal electromotive force phase and the internal electromotive force amplitude, so that the active power response characteristics of the grid-forming device under different power grid strengths are consistent or tend to be consistent.

[0020] In some possible embodiments, obtaining the internal electromotive force phase of the grid-forming device matched with the power grid strength parameter includes: obtaining a preset damping coefficient of an active power synchronization loop matched with the power grid strength parameter; and obtaining the internal electromotive force phase matched with the power grid strength parameter by the active power synchronization loop based on the damping coefficient.

[0021] In some possible embodiments, the obtaining of the preset damping coefficient of the active power synchronization ring matched with the grid strength parameter comprises: obtaining the damping coefficient matched with the grid strength parameter according to the grid strength parameter and a pre-established damping correlation relationship, wherein the damping correlation relationship represents the grid strength and the damping coefficient that make the active power response characteristics of the grid-forming device under different grid strengths consistent or tend to be consistent.

[0022] In some possible embodiments, the damping correlation relationship comprises a value range of a pair of intermediate parameters and a damping ratio, the intermediate parameters being related to the grid strength parameter, and the damping ratio being related to the damping coefficient.

[0023] In some possible embodiments, the obtaining of the damping coefficient matched with the grid strength parameter according to the grid strength parameter and the pre-established damping correlation relationship comprises: in the damping correlation relationship, searching for a target damping ratio corresponding to the intermediate parameter related to the grid strength parameter; and obtaining the damping coefficient related to the target damping ratio as the damping coefficient matched with the grid strength parameter.

[0024] In some possible embodiments, the method further comprises: configuring a plurality of different damping ratios; and calculating intermediate parameters corresponding to the damping ratios, the intermediate parameters and the corresponding damping ratios making the active power response characteristics of the grid-forming device under different grid strengths consistent or tend to be consistent.

[0025] In some possible embodiments, the grid-forming device comprises a grid-side converter configured to be connected with the grid.

[0026] The obtaining of the internal electromotive force phase of the grid-forming device matched with the grid strength parameter comprises: obtaining the damping coefficient of the active power synchronization ring by using the second-order system characteristics of the active power synchronization ring based on the impedance between the grid-side converter and the grid, a preset inertial time constant and a preset angular velocity parameter; and performing active power synchronization operation according to the damping coefficient, the inertial time constant and the control parameter of the active power synchronization ring to obtain the internal electromotive force phase of the grid-forming device.

[0027] In some possible embodiments, the obtaining of the internal electromotive force amplitude of the grid-forming device comprises: performing reactive power closed-loop control operation according to the control parameter of the reactive power ring to obtain the internal electromotive force amplitude of the grid-forming device.

[0028] In some possible embodiments, the control of the grid-forming device based on the internal electromotive force phase and the internal electromotive force amplitude comprises: controlling the grid-side converter to operate by using the PWM signal generated based on the internal electromotive force phase and the internal electromotive force amplitude.

[0029] In some possible embodiments, the active power response characteristics comprise an active power response time and an active power output value.

[0030] The embodiment of the present application further provides a control device of a grid-forming device, the control device comprising: a phase acquisition module configured to acquire an internal potential phase of the grid-forming device matched with a grid strength parameter, the grid strength parameter being used to represent grid strength; an amplitude acquisition module configured to acquire an internal potential amplitude of the grid-forming device; and a modulation module configured to control the grid-forming device based on the internal potential phase and the internal potential amplitude, so that the active power response characteristics of the grid-forming device under different grid strengths are consistent or tend to be consistent.

[0031] The embodiment of the present application further provides a controller of a grid-forming device, comprising a processor and a memory storing computer program instructions; and the processor implements the control method of the grid-forming device in the embodiment of the present application when executing the computer program instructions.

[0032] In some possible embodiments, the controller is arranged in a converter of the grid-forming device.

[0033] The embodiment of the present application further provides a grid-forming device comprising the controller of the grid-forming device in the embodiment of the present application.

[0034] The embodiment of the present application further provides a computer readable storage medium, the computer readable storage medium storing computer program instructions, and the computer program instructions are executed by a processor to implement the control method of the grid-forming device in the embodiment of the present application.

[0035] The embodiment of the present application provides a control method, device, controller, equipment and medium of a grid-forming device, which can obtain a damping coefficient of an active power synchronization ring based on impedance, inertial time constant and angular velocity parameters of a grid-side converter to a grid, the damping coefficient being matched with the impedance between the grid-side converter and the grid. An internal potential phase of the grid-forming device is obtained according to the damping coefficient, the inertial time constant and control parameters of the active power synchronization ring. An internal potential amplitude of the grid-forming device is obtained according to control parameters of a reactive power ring. Different damping coefficients of the active power synchronization ring are obtained according to different impedance between the grid-side converter and the grid, and the internal potential phase is affected by the damping coefficient, so that a PWM signal generated by combining the internal potential phase and the internal potential amplitude controls the grid-side converter, realizes the predictability of the active power response characteristics of the grid-forming device under different grid strengths, makes the active power response characteristics of the grid-forming device under different grid strengths consistent or tend to be consistent, reduces or even avoids the instability risk of a power system, and improves the safety and reliability of the power system.

[0036] The embodiment of the present application provides a control method and device of grid-forming equipment, a controller and a medium, the internal potential phase of the grid-forming equipment matched with the grid strength can be acquired, the internal potential phase is matched with the grid strength parameter, and the internal potential phase can make the active power response characteristics of the grid-forming equipment under different grid strengths consistent or tend to be consistent. The internal potential phase is used to control the converter modulation according to the internal potential amplitude of the acquired grid-forming equipment, the control of the converter modulation is affected by the internal potential phase, the predictability of the active power response characteristics of the grid-forming equipment under different grid strengths is realized, the active power response characteristics of the grid-forming equipment under different grid strengths are consistent or tend to be consistent, the safety, stability and reliability of the grid-forming equipment are improved, and then the safety, stability and reliability of the power system where the grid-forming equipment is located are improved. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced, and other drawings can be obtained by those of ordinary skill in the art without creative labor on the premise that the drawings are not creative labor.

[0038] Fig. 1 is a structural schematic diagram of an example of the grid-forming equipment provided by the embodiment of the present application;

[0039] Fig. 2 is a flowchart of the control method of the grid-forming equipment provided by the embodiment of the present application;

[0040] Fig. 3 is a schematic diagram of an example of the active power response of the grid-forming equipment under different SCRs obtained by the control method with a fixed damping coefficient;

[0041] Fig. 4 is a schematic diagram of an example of the active power response of the grid-forming equipment obtained by the control method with the damping coefficient self-adjustment in the embodiment of the present application;

[0042] Fig. 5 is a flowchart of the control method of the grid-forming equipment provided by another embodiment of the present application;

[0043] Fig. 6 is a schematic diagram of an example of the active power ring synchronization control provided by the embodiment of the present application;

[0044] Fig. 7 is a schematic diagram of an example of the reactive power ring control provided by the embodiment of the present application;

[0045] Fig. 8 is a schematic diagram of an example of the grid-forming equipment control provided by the embodiment of the present application;

[0046] Fig. 9 is a structural schematic diagram of the control device of the grid-forming equipment provided by the embodiment of the present application;

[0047] Fig. 10 is a structural schematic diagram of the controller of the grid-forming equipment provided by the embodiment of the present application;

[0048] FIG. 11 is a structural schematic diagram of a network-constructing device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0049] The features and exemplary embodiments of various aspects of the present application will be described below in detail, in order to make the purposes, technical solutions and advantages of the present application more clear and apparent, the present application will be further described in detail below in combination with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, but not to limit the present application. For those skilled in the art, the present application can be implemented without some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application. It should be noted that the acquisition, storage, use, processing, etc. of information and data in the embodiments of the present application are authorized by the user or relevant institution and comply with relevant regulations of national laws and regulations.

[0050] With the development of clean energy technologies such as wind power generation technology and photovoltaic power generation technology, the proportion of clean energy devices such as wind turbines and photovoltaic devices in the power system is gradually increasing, making the power system including clean energy devices and the power grid have the trend of reduced inertia and weakened strength. In order to cope with power demand and environmental pressure, a network-constructing control strategy can be used to provide damping and inertia for the power system by using network-constructing devices, which can quickly respond when the grid frequency changes and support the stability of the power system. However, due to the differences in the structure of the power system, the grid strength in different regions of the power system is different, and the network-constructing control of the network-constructing device uses a fixed damping coefficient to simulate the damping characteristics, making the active power response characteristics of the network-constructing device under different grid strengths inconsistent and unpredictable, affecting the network-constructing performance of the power system. The active power response characteristics of the network-constructing device under different grid strengths when the grid frequency changes are different, and the support characteristics of the grid are inconsistent, thereby making the power system have the risk of instability, and reducing the safety and reliability of the power system.

[0051] The application provides a control method and device of grid-forming equipment, a controller, equipment and a medium. A damping coefficient under different grid strengths is obtained according to the second-order system characteristics of an active power synchronous ring. An internal electromotive force phase of the grid-forming equipment is obtained according to the obtained damping coefficient and other control parameters of the active power synchronous ring. The internal electromotive force phase is the phase of the internal electromotive force. An internal electromotive force amplitude of the grid-forming equipment is obtained according to the control parameters of a reactive power ring. The internal electromotive force amplitude is the amplitude of the internal electromotive force. A modulation signal of a grid-side converter of the grid-forming equipment is generated according to the internal electromotive force phase and the internal electromotive force amplitude of the grid-forming equipment, so as to control the grid-side converter. The damping coefficient is set according to the grid strength, so that the active power response characteristics of the grid-forming equipment under different grid strengths are consistent or tend to be consistent. The performance of the active control of the grid-forming equipment is improved. The instability risk caused by the inconsistent active power response characteristics of the grid-forming equipment under different grid strengths is eliminated. The safety and reliability of the power system are improved.

[0052] The grid-side converter is a common power electronic device connected between the grid-forming equipment and the grid. Because the grid usually presents an alternating current characteristic, the grid-side converter also needs to output alternating current, so as to ensure the connection between the grid-forming equipment and the grid. However, the grid-side converter can be implemented by selecting different power electronic devices according to different grid-forming equipment. For example, when the grid-forming equipment is a direct-current power generation unit (such as photovoltaic), the grid-side converter can be a photovoltaic inverter; when the grid-forming equipment is a wind turbine generator, the grid-side converter can be an AC-DC-AC converter or a DC-AC converter.

[0053] For ease of understanding, a network-forming device is first introduced briefly. FIG. 1 is a structural schematic diagram of an example of network-forming equipment provided in an embodiment of the present application. As shown in FIG. 1, the network-forming device in the embodiment of the present application can include a simulated virtual energy source 11 and a grid-side converter 12. The energy source 11 can be electrically connected to the grid-side converter 12 through a DC bus, and the grid-side converter 12 is connected to a power grid 21. The energy source 11 can include, but is not limited to, energy storage batteries, wind turbines, photovoltaic devices, etc. In the case where the energy source 11 includes a wind turbine, the network-forming device can be a network-forming wind turbine. The network-forming wind turbine can include a converter, and the network-forming wind turbine can be connected to the power grid through the converter. The connection and structure of the converter in the network-forming wind turbine can refer to the grid-side converter 12, and will not be described herein again. The grid-side converter 12 includes a plurality of switching devices, for example, the grid-side converter can include a plurality of Insulate-Gate Bipolar Transistors (IGBTs) or other types of switching devices. The conversion function of the grid-side converter 12 is realized through the cooperation of the conduction and turn-off of the plurality of switching devices. The inductance Lf in FIG. 1 represents the inductance of the grid-side converter, PCC is the point of common coupling of the network-forming device and the power grid 21, and the impedance Zg represents the line impedance between the network-forming device and the power grid 21, that is, can represent the impedance between the network-forming device and the power grid 21. In the embodiment of the present application, the parameters that can affect the internal potential phase of the network-forming device can be set according to the grid strength when the network-forming device such as the network-forming wind turbine is in an offline state, that is, the network-forming device is in a shutdown state and is not running. Then, in the process of running the network-forming device, based on the parameters that can affect the internal potential phase of the network-forming device set, the grid-side converter 12 is controlled through the active power synchronous loop control combined with the control of the reactive power loop, so that the active power response characteristics of the network-forming device under different grid strengths are consistent or tend to be consistent.

[0054] The control method, device, controller, equipment and medium of the network-forming device provided in the present application are described below respectively.

[0055] The present application provides a control method of a network-forming device, which is applied to the network-forming device. The control method of the network-forming device can be executed by a control device, a controller, etc. of the network-forming device, which is not limited herein. FIG. 2 is a flow chart of the control method of the network-forming device provided in an embodiment of the present application. As shown in FIG. 2, the control method of the network-forming device can include steps S301 to S304.

[0056] In step S301, based on the impedance between the grid-side converter and the power grid, the preset inertia time constant and the preset angular velocity parameter, the damping coefficient of the active power synchronous loop is obtained by using the second-order system characteristics of the active power synchronous loop.

[0057] The impedance between the grid-side converter and the grid is the impedance between the grid-forming device and the grid. In the embodiments of the present application, the grid strength can be represented by a short-circuit ratio (SCR), which can be the ratio of the three-phase short-circuit capacity of an access bus to which the grid-side converter is electrically connected to the capacity of the grid-forming device. The three-phase short-circuit capacity can be the short-circuit capacity provided by the energy source simulated by the grid-forming device. The inertia time constant can describe the ability of the grid-forming device to release kinetic energy to resist changes in grid frequency in the case of power imbalance. In the embodiments of the present application, the inertia time constant is set in advance according to scenarios, requirements, etc. For example, if the grid-forming device is a grid-forming wind turbine, the inertia time constant can be set according to the requirements of regional industry standards or regional standards. The angular velocity parameter can include some parameters related to the angular velocity given in the control process of the grid-forming device. In some examples, the angular velocity parameter can include an active power synchronization loop cutoff angular velocity and a rated angular velocity of the grid. The active power synchronization loop cutoff angular velocity is the bandwidth corresponding to a 3dB drop in the closed-loop frequency characteristic curve of the active power synchronization loop with respect to zero frequency, which can be used to measure the characteristics of the transient response of the power system. The active power synchronization loop cutoff angular velocity and the rated angular velocity of the grid can be set according to scenarios, requirements, experience, etc. For example, the rated angular velocity of the grid can also be referred to as the rated angular velocity of the grid voltage, and the rated angular velocity of the grid can be 314 rad / s (314 radian / s), but is not limited thereto.

[0058] The grid-forming device adopts an active power synchronization loop to simulate the inertia and damping characteristics of a synchronous generator, and obtains an internal electromotive force phase of the generator according to the calculation. The internal electromotive force phase is the phase of the internal electromotive force. The internal electromotive force is an equivalent internal voltage source constructed to simulate the electromechanical transient characteristics of the synchronous generator, and the amplitude and frequency of the internal electromotive force can be dynamically generated by a virtual synchronous control algorithm according to the active power-frequency characteristic and the reactive power-voltage characteristic. The internal electromotive force of the grid-forming device can represent the equivalent synchronous characteristics presented by the grid-forming device. The internal electromotive force phase of the generator in the above is equivalent to the internal electromotive force phase of the grid-forming device. The measured active power of the grid-side converter is equivalent to the measured active power of the grid-forming device, and the reference active power of the grid-side converter is equivalent to the reference active power of the grid-forming device. The closed-loop transfer function of the active power synchronization loop can be embodied by the ratio of the change in the measured active power of the grid-side converter (i.e., the change in the actual output active power of the grid-forming device) to the change in the reference active power of the grid-side converter (i.e., the change in the reference active power of the grid-forming device), as shown in the following formula (1):

[0059] wherein, is the change in the measured active power of the grid-side converter; is the change in the reference active power of the grid-side converter; ω Nis the rated angular velocity of the power grid; K x is the inverse of the impedance between the grid-side converter and the power grid, i.e., the inverse of the line impedance between the grid-forming device and the power grid; T J is the inertia time constant; D is the damping coefficient of the active power synchronization loop. From the above formula (1), the closed-loop transfer function of the active power synchronization loop is a typical second-order system transfer function, and correspondingly, the active power synchronization loop has second-order system characteristics.

[0060] The second-order system characteristics are related to the impedance, the inertia time constant, the angular velocity parameter, and the damping coefficient, and correspondingly, the second-order system characteristics of the active power synchronization loop are related to the impedance between the grid-side converter and the power grid, the inertia time constant, the angular velocity parameter, and the damping coefficient of the active power synchronization loop. Through the relationship between the impedance between the grid-side converter and the power grid, the inertia time constant, the angular velocity parameter, and the damping coefficient of the active power synchronization loop in the second-order system characteristics, according to the known impedance between the grid-side converter and the power grid, the inertia time constant, and the angular velocity parameter, the corresponding damping coefficient of the active power synchronization loop can be obtained. The impedance between the grid-side converter and the power grid corresponds to the impedance between the grid-forming device and the power grid.

[0061] In step S302, active power synchronization operation is performed according to the damping coefficient, the inertia time constant, and the control parameter of the active power synchronization loop, and the internal potential phase of the grid-forming device is obtained.

[0062] The control parameters of the active power synchronization loop are used to assist the control operation of the active power synchronization loop. In some examples, the control parameters of the active power synchronization loop can include, but are not limited to, the active power measured by the grid-side converter, the reference active power of the grid-side converter, the internal electromotive force angular velocity, and the rated angular velocity of the power grid. The active power measured by the grid-side converter is the active power output by the grid-connected device, and the reference active power of the grid-side converter is the reference active power of the grid-connected device. The active power measured by the grid-side converter can be the output active power measured by the grid-side converter. The reference active power of the grid-side converter can be the active power of the grid-side converter issued by the controller of the grid-connected device, i.e., the reference active power of the grid-connected device can be the active power reference value issued by the controller of the grid-connected device. For example, if the grid-connected device is a grid-connected wind turbine, the reference active power of the grid-connected wind turbine can be the active power reference value issued by the main controller of the wind farm. The internal electromotive force angular velocity is the internal electromotive force angular velocity of the grid-connected device, and further, the internal electromotive force angular velocity can be the internal electromotive force angular velocity obtained by the grid-connected device through the active power synchronization loop. The active power synchronization loop controls by using the virtual synchronous control technology, so that the grid-side converter has the inertia, damping and other characteristics of a synchronous generator, i.e., the grid-connected device has the inertia, damping and other characteristics of a synchronous generator. In the case where the grid-side converter has the inertia, damping and other characteristics of a synchronous generator, the active power synchronization operation is performed according to the damping coefficient, the inertia time constant, the control parameters of the active power synchronization loop, etc., to obtain the internal electromotive force phase of the grid-connected device. The active power synchronization operation can include difference operation, division operation, integration operation, summation operation, etc. The damping coefficient, the inertia time constant and the control parameters of the active power synchronization loop can be subjected to the active power synchronization operation such as difference operation, division operation, integration operation, summation operation, etc., to obtain the internal electromotive force phase.

[0063] In step S303, the reactive power closed-loop control operation is performed according to the control parameters of the reactive power loop to obtain the internal electromotive force amplitude of the grid-connected device.

[0064] The control parameters of the reactive power loop are used to assist in the reactive power closed-loop control operation. In some examples, the control parameters of the reactive power loop can include, but are not limited to, the reactive power measured by the grid-side converter, the reference reactive power of the grid-side converter, and the rated voltage of the grid-connected device. The reactive power measured by the grid-side converter is the reactive power output by the grid-connected device, and the reference reactive power of the grid-side converter is the reference reactive power of the grid-connected device. Specifically, the reactive power measured by the grid-side converter can be the reactive power output by the grid-side converter, and the reactive power measured by the grid-connected device can be the reactive power output by the grid-connected device. Specifically, the reference reactive power of the grid-side converter can be the reference reactive power of the grid-side converter sent by the controller, and the reference reactive power of the grid-connected device can be the reference reactive power of the grid-connected device sent by the controller. For example, the grid-connected device is a grid-connected wind turbine, and the reference reactive power of the grid-connected device can be the reference reactive power sent by the main controller of the wind farm. The reactive power closed-loop control operation can include difference operation, proportional operation, integral operation, and differential operation. The control parameters of the reactive power loop can be used to perform the reactive power closed-loop control operation, such as difference operation, proportional operation, integral operation, and differential operation, to obtain the internal electromotive force amplitude. The internal electromotive force amplitude can also be referred to as internal electromotive force voltage.

[0065] In step S304, the PWM signal generated based on the internal electromotive force phase and the internal electromotive force amplitude is used to control the operation of the grid-side converter.

[0066] The internal electromotive force phase and the internal electromotive force amplitude can be modulated to generate a pulse width modulation (PWM) signal. The PWM signal can be transmitted to the grid-side converter, and the PWM signal is used to control the conduction and turn-off of the switching devices in the grid-side converter, thereby achieving control of the grid-side converter. Controlling the operation of the grid-side converter is to control the operation of the grid-connected device.

[0067] In the embodiments of the present application, the damping coefficient of the active power synchronization loop can be obtained based on the impedance, the inertia time constant and the angular velocity parameter of the grid-side converter to the power grid, and the damping coefficient matches the impedance of the grid-side converter to the power grid. According to the damping coefficient, the inertia time constant and the control parameter of the active power synchronization loop, the internal electromotive force phase of the grid-forming device is obtained. According to the control parameter of the reactive power loop, the internal electromotive force amplitude of the grid-forming device is obtained. The stability of different power grids is usually different, which can be described by the grid strength. When the grid-forming device is connected to different power grids, the impedance of the grid-side converter to the power grid is usually different, that is, the impedance of the grid-forming device to the power grid is usually different, which can be specifically reflected in the damping coefficient of the active power synchronization loop. By obtaining the damping coefficient of the active power synchronization loop related to the grid strength, the internal electromotive force phase of the grid-forming device is further determined through the damping coefficient, and then the PWM signal is generated by combining the internal electromotive force phase and the internal electromotive force amplitude to control the grid-side converter, so as to realize the predictability of the active power response characteristic of the grid-forming device under different grid strengths, make the active power response characteristic of the grid-forming device under different grid strengths consistent or tend to be consistent, reduce or even avoid the instability risk of the power system, and improve the safety and reliability of the power system.

[0068] In order to reflect the effect of the control method of the grid-forming device in the embodiments of the present application, the active power obtained by using the control method with a fixed damping coefficient and the active power obtained by using the control method of the grid-forming device in the embodiments of the present application are monitored respectively under the same test conditions, and the difference in active power response characteristics of the two control methods is obtained. FIG. 3 is a schematic diagram of an example of the active power response of the grid-forming device under different SCRs obtained by using the control method with a fixed damping coefficient, which can show the active power response of the grid-forming device under different grid strengths (here, the grid strength is represented by SCR) when using a fixed damping coefficient. FIG. 4 is a schematic diagram of an example of the active power response of the grid-forming device obtained by using the control method with self-tuning of the damping coefficient in the embodiments of the present application, which can show the active power response of the grid-forming device under different grid strengths when using the damping coefficient selection method in the embodiments of the present application. The test condition is that the active power of the grid-forming device is stepped from 0 kW to 3000 kW. In FIG. 3 and FIG. 4, the horizontal axis represents time (unit: second), and the vertical axis represents the active power value (unit: kW). Here, the active power value is the actual active power output value of the grid-forming device. The purple curve, the yellow curve, the red curve and the blue curve respectively correspond to the active power response characteristic curves when the short circuit ratio is 20, the short circuit ratio is 10, the short circuit ratio is 5 and the short circuit ratio is 2. The active power response characteristic can be reflected by the active power response time and the active power output value. In FIG. 3, the active power response times required for the active power values of the curves corresponding to different short circuit ratios to change from the occurrence to the stability are inconsistent, and the active power response times of the grid-forming device are also quite different when the grid strength is different (i.e. under different short circuit ratios). The lower the grid strength (i.e. the more unstable the grid), the longer the active power response time required for the grid-forming device to reach the steady state. In addition, in FIG. 3, there is a large gap between the active power corresponding to different short circuit ratios at the same time, for example, at 1.5 seconds, the active power value corresponding to the short circuit ratio of 2 and the active power value corresponding to the short circuit ratio of 10 have a large difference. In FIG. 4, the active power response times required for the active power values of the curves corresponding to different short circuit ratios to change from the occurrence to the stability are quite small and tend to be consistent. The active power response curves under different short circuit ratios are very close in FIG. 4 at the same time, for example, at 1.5 seconds, the active power value corresponding to the short circuit ratio of 2 and the active power value corresponding to the short circuit ratio of 10 have a small difference and tend to be consistent. In summary, by using the control method of the grid-forming device provided in the embodiments of the present application, the consistency of the active power response characteristics of the grid-forming device under different short circuit ratios (i.e. different grid strengths) can be improved, so that the grid-forming device connected to the power system is more secure and stable.

[0069] In some embodiments, the damping coefficient can be obtained by using a pre-established damping correspondence table, so as to realize the active power synchronization operation according to the damping coefficient. FIG. 5 is a flowchart of a control method of a grid-connected device according to another embodiment of the present application. The difference between FIG. 5 and FIG. 2 is that step S301 in FIG. 2 can be specifically refined as steps S3011 to S3013 in FIG. 5, step S302 in FIG. 2 can be specifically refined as steps S3021 to S3024 in FIG. 5, and step S303 in FIG. 2 can be specifically refined as steps S3031 and S3032 in FIG. 5.

[0070] In step S3011, a target intermediate parameter is obtained according to an impedance between the grid-side converter and the power grid, an inertia time constant, an angular velocity parameter, and a second-order system characteristic.

[0071] The target intermediate parameter is an intermediate parameter calculated according to the impedance between the grid-side converter and the power grid, the inertia time constant, and the angular velocity parameter. Under the condition of the second-order system characteristic, the target intermediate parameter is negatively correlated with an inverse of the impedance between the grid-side converter and the power grid, and is positively correlated with the inertia time constant. In some examples, the angular velocity parameter can include an active power synchronization loop cutoff angular velocity and a rated angular velocity of the power grid, the active power synchronization loop cutoff angular velocity is positively correlated with the target intermediate parameter, and the rated angular velocity of the power grid is negatively correlated with the target intermediate parameter. For example, the target intermediate parameter can be calculated according to the following formula (2):

[0072] wherein K α is the target intermediate parameter, ω b is the active power synchronization loop cutoff angular velocity, T J is the inertia time constant, ω N is the rated angular velocity of the power grid, and K x is an inverse of the impedance between the grid-side converter and the power grid, i.e., an inverse of a line impedance between the grid-connected device and the power grid.

[0073] In step S3012, a target damping ratio corresponding to the target intermediate parameter in the damping correspondence table is determined in the pre-established damping correspondence table.

[0074] The intermediate parameter has a corresponding relationship with the damping ratio, and according to the second-order system characteristics, the damping ratio also has a correlation relationship with the damping coefficient. The damping corresponding relationship table can be established in advance, and the damping corresponding relationship table can represent the corresponding relationship between the intermediate parameter and the damping ratio. The damping corresponding relationship table can represent the damping correlation relationship, and the damping correlation relationship includes the value range of the intermediate parameter and the damping ratio in pairs. The damping correlation relationship can include the power grid strength and the damping coefficient, which make the active power response characteristics of the grid-forming device under different power grid strengths consistent or tend to be consistent. In some examples, the damping correlation relationship can be the damping corresponding relationship table in the above embodiments, but is not limited thereto. The intermediate parameter is related to the power grid strength parameter, and the damping ratio is related to the damping coefficient. The value range of the intermediate parameter and the damping ratio in different pairs in the damping correlation relationship participate in the calculation of the internal potential phase, and the obtained internal potential phase can make the active power response characteristics of the grid-forming device under different power grid strengths consistent or tend to be consistent. The intermediate parameter can be calculated based on the power grid strength, and the damping coefficient can be calculated based on the damping ratio. The damping corresponding relationship table can include the corresponding relationship between the damping ratio and the value range of the intermediate parameter. For example, the damping corresponding relationship table can be represented by the following formula (3):

[0075] wherein, ξ is the damping ratio; ξ1, ξ2, …, ξn are different values of the damping ratio; K1, K2, …, Kn are different values of the damping coefficient; and φ1, φ2, …, φn are different value ranges of the intermediate parameter. n β1 α β2 β2 α β3 βn α β(n+1) The damping corresponding relationship table can also be represented in the form of a table, which is not specifically illustrated here.

[0076] ​​​​​​​​​In some examples, before executing step S3012, a damping correlation can be established in advance by configuring multiple different damping ratios; that is, a damping correspondence table can be established in advance. Specifically, multiple different damping ratios can be obtained, and based on the second-order system characteristics and the multiple different damping ratios, the value range of intermediate parameters corresponding to the multiple different damping ratios can be calculated. Based on the multiple different damping ratios and the value range of the corresponding intermediate parameters, a damping correspondence table between intermediate parameters and damping ratios can be established. The second-order system characteristics include the relationship between intermediate parameters and damping ratios. Given the correspondence between intermediate parameters and damping ratios, the corresponding intermediate parameters can be calculated using the known damping ratios. In other words, multiple different damping ratios can be configured; the intermediate parameters corresponding to each damping ratio can be calculated, and the intermediate parameters and corresponding damping ratios make the active power response characteristics of the grid-type equipment consistent or tend to be consistent under different grid intensities. For each configured damping ratio, the intermediate parameters corresponding to the damping ratio can be calculated based on the relationship between the damping coefficient and the damping ratio, the relationship between the damping coefficient and the grid strength parameters in the second-order system characteristics, and the relationship between the grid strength parameters and the intermediate parameters. Based on multiple damping ratios and the intermediate parameters corresponding to each damping ratio, the value range of the paired intermediate parameters and the damping ratio can be obtained, that is, the damping correlation relationship can be obtained. In order to form the value range of multiple intermediate parameters, multiple different damping ratios can be selected first. For each damping ratio, the intermediate parameters corresponding to the damping ratio can be calculated using the second-order system characteristics. By summarizing the intermediate parameters corresponding to multiple damping ratios, the correspondence between the value range of the damping ratio and the intermediate parameters can be obtained. For example, the relationship between the damping ratio and the intermediate parameters in the second-order system characteristics can be shown in the following formula (4):

[0077] Among them, K β ξ is an intermediate parameter; ξ is the damping ratio. If we substitute ξ1 from equation (3) into equation (4) to calculate K... β The value range of should be [K] β1 ,K β2 Similarly, substituting ξ2 from equation (3) into equation (4) yields the calculated K. β The value range of should be [K] β2 ,K β3 Examples will not be provided here. By establishing multiple damping ratios and the correspondence between the values ​​of intermediate parameters calculated from the multiple damping ratios and the characteristics of the second-order system, a damping correspondence table between intermediate parameters and damping ratios can be established.

[0078] For example, configure n damping ratios, namely ξ1, ξ2, ..., ξ3. n According to equation (4) in the above embodiment, the intermediate parameter K corresponding to the damping ratio ξ1 can be calculated. β1 The intermediate parameter K corresponding to the damping ratio ξ2β2 …, and damping ratio ξ n corresponding intermediate parameter K βn , so as to obtain the damping correlation relationship as shown in the above formula (3). It should be noted that K βn ≤ K α < K β(n+1) may also be replaced by K α ≥ K βn .

[0079] In some examples, the value range of the intermediate parameter to which the target intermediate parameter falls can be determined in the damping correspondence table of the intermediate parameter and the damping ratio, and the damping ratio corresponding to the value range of the intermediate parameter is determined as the target damping ratio in the damping correspondence table. For example, as shown in the above formula (4), after obtaining the target intermediate parameter K α , if K α falls in [K β1 , K β2 ], the damping ratio corresponding to the parameter range in the damping correspondence table of the intermediate parameter and the damping ratio is ξ1, and the target damping ratio can be determined as ξ1; if K α falls in [K β2 , K β3 ], the damping ratio corresponding to the parameter range in the damping correspondence table of the intermediate parameter and the damping ratio is ξ2, and the target damping ratio is determined as ξ2. It is more convenient and fast to use the damping correspondence table of the intermediate parameter and the damping ratio to find the target damping ratio corresponding to the target intermediate parameter.

[0080] In other examples, the corresponding damping ratio can be calculated according to the relationship between the damping ratio and the intermediate parameter in the second-order system characteristics and the target intermediate parameter, and the corresponding damping ratio is determined as the target damping ratio each time the target intermediate parameter is obtained. The relationship between the damping ratio and the intermediate parameter in the second-order system characteristics can be referred to the related description in the above examples, which will not be described here.

[0081] In step S3013, the damping coefficient is obtained according to the target damping ratio, the angular velocity parameter, the inertia time constant, the impedance of the grid-side converter to the power grid, and the second-order system characteristics.

[0082] The second-order system characteristics include the functional relationship between the damping ratio, the angular velocity parameter, the inertia time constant, the impedance of the grid-side converter to the power grid, and the damping coefficient. In the case where the functional relationship and the damping ratio, the angular velocity parameter, the inertia time constant, and the impedance of the grid-side converter to the power grid are known, the corresponding damping coefficient can be calculated. In the second-order system characteristics, the damping ratio, the angular velocity parameter, the inertia time constant, and the damping coefficient are positively correlated, and the impedance of the grid-side converter to the power grid and the damping coefficient are negatively correlated. For example, the damping coefficient can be calculated according to the following formula (5):

[0083] wherein D is a damping coefficient; ξ is a target damping ratio; ω N is a rated angular velocity of the power grid; K x is an inverse of impedance of the grid-side converter to the power grid; T J is an inertia time constant.

[0084] In step S3021, a torque increment of the grid-connected device is obtained according to a difference between the reference active power and the measured active power, and the internal electromotive force angular velocity.

[0085] The difference between the reference active power and the measured active power can represent a difference between the actual output active power of the grid-side converter and the reference active power. The difference between the active power can be divided by the internal electromotive force angular velocity to convert the difference between the active power into the torque increment, and the torque increment is used for the next calculation.

[0086] In step S3022, an angular velocity increment is obtained according to the torque increment, the inertia time constant and the damping coefficient.

[0087] The inertia time constant and the damping coefficient can be used to obtain a mathematical model with inertia and damping characteristics. The torque increment is used as an input of the mathematical model with inertia and damping characteristics, and the output angular velocity increment is obtained.

[0088] In step S3023, an integral operation is performed on a sum of the rated angular velocity and the angular velocity increment, and an internal electromotive force phase is obtained.

[0089] For example, FIG. 6 is a schematic diagram of an example of the active power loop synchronization control provided by the embodiments of the present application. As shown in FIG. 6, a difference between the reference active power and the measured active power is divided by the internal electromotive force angular velocity ω * to obtain an operation result, i.e., a torque increment. The operation result is used as an input of a mathematical model to obtain an output of the mathematical model, i.e., an angular velocity increment Δω, wherein T J is an inertia time constant, D is a damping coefficient, and s is a Laplace operator. The angular velocity increment Δω is added to a rated angular velocity ω N of the power grid, and an integral operation is performed on the sum to obtain an internal electromotive force phase θ. In FIG. 6, is the integral operation.

[0090] In step S3031, a closed-loop control operation is performed on a difference between the reference reactive power and the measured reactive power to obtain a voltage increment of the grid-connected device.

[0091] The closed-loop control operation includes at least one of proportional operation, integral operation and derivative operation, for example, the closed-loop control operation can be implemented as proportional operation, integral operation, proportional integral operation or proportional integral derivative operation. The difference between the reference reactive power and the measured reactive power is taken as the input of the closed-loop control operation, and the output of the closed-loop control operation is the voltage increment of the grid-connected device.

[0092] In step S3032, the sum of the voltage increment and the rated voltage is determined as the internal electromotive force amplitude.

[0093] For example, FIG. 7 is a schematic diagram of an example of reactive power loop control provided by the embodiments of the present application. As shown in FIG. 7, the difference between the reference reactive power Q ref and the measured reactive power Q meas is taken as the input of the closed-loop control operation, and the output of the closed-loop control operation is the voltage increment ΔU. The sum of the voltage increment and the rated voltage U * of the grid-connected device is determined as the internal electromotive force amplitude U.

[0094] FIG. 8 is a schematic diagram of an example of grid-connected device control provided by the embodiments of the present application. The structure of the grid-connected device in FIG. 8 can be referred to FIG. 1, which will not be described here. As shown in FIG. 8, the internal electromotive force phase θ and the internal electromotive force amplitude U are signal-modulated to obtain a PWM signal, which can be input to the grid-side converter 12 to control the cooperation of the on and off of the switching devices in the grid-side converter 12, so as to control the grid-side converter to make the active power response characteristics of the grid-connected device consistent or tend to be consistent under different grid strengths (i.e. different short-circuit ratios). Here, the consistency or tendency to be consistent of the active power response characteristics of the grid-connected device can mean that the difference between the active power response characteristics of the grid-connected device under different grid strengths is within a preset standard range, which can be set according to the scene, demand, experience, etc., and is not limited here.

[0095] The embodiments of the present application also provide a control device of a grid-connected device, which is applied to the grid-connected device. The grid-connected device includes a grid-side converter configured to be connected with a power grid. FIG. 9 is a structural schematic diagram of the control device of the grid-connected device provided by an embodiment of the present application. As shown in FIG. 9, the control device 400 of the grid-connected device can include a damping coefficient setting module 401, a phase determining module 402, an amplitude determining module 403 and a control module 404.

[0096] The damping coefficient setting module 401 can be used to obtain the damping coefficient of the active power synchronization loop based on the impedance between the grid-side converter and the power grid, the preset inertia time constant and the preset angular velocity parameter, and the second-order system characteristics of the active power synchronization loop.

[0097] The phase determination module 402 can be configured to perform active power synchronization operation according to the damping coefficient, the inertia time constant and the control parameter of the active power synchronization loop, to obtain the internal electromotive force phase of the grid-connected device.

[0098] The amplitude determination module 403 can be configured to perform reactive power closed-loop control operation according to the control parameter of the reactive power loop, to obtain the internal electromotive force amplitude of the grid-connected device.

[0099] The control module 404 can be configured to control the grid-side converter to operate by using the PWM signal generated based on the internal electromotive force phase and the internal electromotive force amplitude.

[0100] In some embodiments, the damping coefficient setting module 401 can be specifically configured to: obtain a target intermediate parameter according to the impedance between the grid-side converter and the power grid, the inertia time constant, the angular velocity parameter and the second-order system characteristic; determine a target damping ratio corresponding to the target intermediate parameter in a damping corresponding relationship table in the damping corresponding relationship table, the damping corresponding relationship table including the corresponding relationship between the damping ratio and the intermediate parameter value range; and obtain the damping coefficient according to the target damping ratio, the angular velocity parameter, the inertia time constant, the impedance between the grid-side converter and the power grid and the second-order system characteristic.

[0101] In some examples, the control device 400 of the grid-connected device can further include a relationship table generation module. The relationship table generation module can be configured to: obtain a plurality of different damping ratios, and obtain the intermediate parameter value range corresponding to the plurality of different damping ratios according to the second-order system characteristic and the plurality of different damping ratios; and establish the damping corresponding relationship table according to the plurality of different damping ratios and the corresponding intermediate parameter value range.

[0102] In some examples, the damping coefficient setting module 401 can be specifically configured to: determine the intermediate parameter value range in which the target intermediate parameter falls in the damping corresponding relationship table; and determine the corresponding damping ratio of the intermediate parameter value range in the damping corresponding relationship table as the target damping ratio.

[0103] In some examples, the angular velocity parameter includes the active power synchronization loop cutoff angular velocity and the rated angular velocity of the power grid.

[0104] In some embodiments, the control parameter of the active power synchronization loop includes the measured active power of the grid-side converter, the reference active power of the grid-side converter, the internal electromotive force angular velocity and the rated angular velocity of the power grid. The phase determination module 402 can be specifically configured to: obtain the torque increment of the grid-connected device according to the difference between the reference active power and the measured active power and the internal electromotive force angular velocity; obtain the angular velocity increment according to the torque increment, the inertia time constant and the damping coefficient; and perform integral operation on the sum of the rated angular velocity and the angular velocity increment, to obtain the internal electromotive force phase.

[0105] In some embodiments, the control parameter of the reactive power loop includes a measured reactive power of the grid-side converter, a reference reactive power of the grid-side converter, and a rated voltage of the grid-connected device. The magnitude determination module 403 can be specifically configured to: perform a closed-loop control operation on a difference between the reference reactive power and the measured reactive power to obtain a voltage increment of the grid-connected device, the closed-loop control operation including at least one of proportional operation, integral operation, and differential operation; and determine, as the internal potential magnitude, a sum of the voltage increment and the rated voltage.

[0106] It should be noted that the control device 400 of the grid-connected device is a device corresponding to the control method of the grid-connected device described above, and all implementation manners in the method embodiments are applicable to the device embodiments, and the same technical effects can be achieved, which will not be described herein again.

[0107] The application further provides a controller of a grid-connected device. FIG. 10 is a structural schematic diagram of a controller of a grid-connected device according to an embodiment of the application. As shown in FIG. 10, the controller 500 of the grid-connected device includes a memory 501, a processor 502, and a computer program stored in the memory 501 and executable on the processor 502.

[0108] In some examples, the processor 502 can include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement one or more embodiments of the application.

[0109] The memory 501 can include a read-only memory (ROM), a random access memory (RAM), a magnetic disk storage medium device, an optical storage medium device, a flash memory device, an electrical, optical, or other physical / tangible memory storage device. Therefore, generally, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the control method of the grid-connected device according to embodiments of the application.

[0110] The processor 502 runs a computer program corresponding to the executable program code stored in the memory 501 by reading the executable program code, to implement the control method of the grid-connected device in the above embodiments.

[0111] In some examples, the controller 500 of the network equipment device can further include a communication interface 503 and a bus 504. As shown in FIG. 10, the memory 501, the processor 502, and the communication interface 503 are connected through the bus 504 and complete communication with each other.

[0112] The communication interface 503 is mainly used to realize the communication between various modules, devices, units and / or equipment in the embodiments of the present application. The input device and / or the output device can also be accessed through the communication interface 503.

[0113] The bus 504 includes hardware, software or both to couple the components of the controller 500 of the network equipment device to each other. By way of example, and not limitation, the bus 504 can include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-E) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VLB) bus, or another suitable bus or a combination of two or more of these. Where appropriate, the bus 504 can include one or more buses. Although the present embodiments describe and show a particular bus, the present application contemplates any suitable bus or interconnect.

[0114] In some embodiments, the controller of the network equipment device can be disposed in a converter of the network equipment device, which can be the grid-side converter in the above embodiments.

[0115] The application further provides a grid-forming device. FIG. 11 is a structural schematic diagram of a grid-forming device according to an embodiment of the application. The difference between FIG. 11 and FIG. 1 is that the grid-forming device shown in FIG. 11 further includes a controller 13 of the grid-forming device. The controller 13 of the grid-forming device can be connected with the converter, can execute the control method of the grid-forming device in the above embodiment, and achieve the same technical effects. For the sake of brevity, details are not described herein again. In some examples, the grid-forming device can include, but is not limited to, a wind turbine generator, a photovoltaic device, and the like.

[0116] The application further provides a computer-readable storage medium having computer program instructions stored thereon. The computer program instructions, when executed by a processor, can implement the control method of the grid-forming device in the above embodiment and achieve the same technical effects. For the sake of brevity, details are not described herein again. The computer-readable storage medium can include, but is not limited to, a non-transitory computer-readable storage medium such as a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0117] The application further provides a computer program product including a computer program. The computer program, when executed by a processor, implements the control method of the grid-forming device in the above embodiment and achieves the same technical effects. For the sake of brevity, details are not described herein again.

[0118] It should be clear that each of the embodiments in the specification is described in a progressive manner, and the same or similar parts of each of the embodiments can be referred to each other. Each of the embodiments focuses on the difference from other embodiments. For the device embodiment, the controller embodiment, the grid-forming device embodiment, the computer-readable storage medium embodiment, and the computer program product embodiment, the related parts can be referred to the description of the method embodiment. The application is not limited to the specific steps and structures described above and shown in the drawings. Those skilled in the art can make various changes, modifications, and additions, or change the order of the steps, after understanding the spirit of the application. Moreover, for the sake of brevity, detailed description of known methods and techniques is omitted herein.

[0119] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other processing device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other processing device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks. Alternatively, computer program implemented steps can be

[0120] Those skilled in the art will understand that the embodiments described above are merely exemplary and not limiting. Different technical features appearing in different embodiments can be combined to achieve beneficial effects. Those skilled in the art will understand and appreciate other variations of the disclosed embodiments upon studying the drawings, the specification and the claims. In the claims, the term "comprising" does not exclude other devices or steps; the term "one" does not exclude a plurality; the term "first", "second" etc. do not imply any order; the terms "first", "second" etc. are used to name the names and not to indicate any specific order. Any reference signs in the claims should not be construed as limiting the scope of the claims. The functions of a plurality of parts can be carried out by a single hardware or software module. The fact that certain technical features appear in different dependent claims does not mean that these technical features cannot be combined to achieve beneficial effects.

Claims

1. A control method of a grid-forming device connected to a power grid, comprising: obtaining an internal voltage phase of the grid-forming device matching a grid strength parameter, the grid strength parameter being used to represent a grid strength; obtaining an internal voltage amplitude of the grid-forming device; and controlling the grid-forming device based on the internal voltage phase and the internal voltage amplitude, so that active power response characteristics of the grid-forming device under different grid strengths are consistent or tend to be consistent. The obtaining of the internal voltage phase of the grid-forming device matching the grid strength parameter comprises: obtaining a preset damping coefficient of an active power synchronization ring matching the grid strength parameter; and obtaining the internal voltage phase matching the grid strength parameter through the active power synchronization ring based on the damping coefficient. The obtaining of the preset damping coefficient of the active power synchronization ring matching the grid strength parameter comprises: obtaining the damping coefficient matching the grid strength parameter according to the grid strength parameter and a pre-established damping correlation relationship, wherein the damping correlation relationship represents a grid strength and the damping coefficient that make the active power response characteristics of the grid-forming device under different grid strengths consistent or tend to be consistent. The damping correlation relationship comprises a value range of a pair of intermediate parameters and a damping ratio, the intermediate parameters being related to the grid strength parameter, and the damping ratio being related to the damping coefficient.

2. The method of claim 1, wherein, The obtaining of the damping coefficient matching the grid strength parameter according to the grid strength parameter and the pre-established damping correlation relationship comprises: searching for a target damping ratio corresponding to the intermediate parameter related to the grid strength parameter in the damping correlation relationship; and obtaining the damping coefficient related to the target damping ratio as the damping coefficient matching the grid strength parameter. 6.The method of claim 4, further comprising: configuring a plurality of different damping ratios; and calculating the intermediate parameters corresponding to the damping ratios, the intermediate parameters and the corresponding damping ratios making the active power response characteristics of the grid-forming device under different grid strengths consistent or tend to be consistent. The grid-forming device comprises a grid-side converter configured to be connected to the power grid.

3. The method of claim 2, wherein, The obtaining of the internal voltage phase of the grid-forming device matching the grid strength parameter comprises: obtaining a damping coefficient of an active power synchronization ring based on an impedance between the grid-side converter and the power grid, a preset inertia time constant and a preset angular velocity parameter, and utilizing a second-order system characteristic of the active power synchronization ring; and performing active power synchronization operation according to the damping coefficient, the inertia time constant and a control parameter of the active power synchronization ring, to obtain the internal voltage phase of the grid-forming device. The obtaining of the internal voltage amplitude of the grid-forming device comprises: performing reactive power closed-loop control operation according to a control parameter of a reactive power ring, to obtain the internal voltage amplitude of the grid-forming device.

4. The method of claim 3, wherein, The controlling of the grid-forming device based on the internal voltage phase and the internal voltage amplitude comprises:

5. The method of claim 4, wherein, ​ ​ ​ ​ ​ ​ 7. The method of claim 1, wherein, ​ ​ ​ ​ 8. The method of claim 7, wherein, ​ ​ 9. The method of claim 8, wherein, ​ The grid-side converter is controlled by a PWM signal generated based on the internal electromotive force phase and the internal electromotive force amplitude.

10. The method of any one of claims 1 to 9, wherein, The active power response characteristic includes an active power response time and an active power output value. 11.A control device of a grid-forming device, the control device comprising: a phase acquisition module configured to acquire an internal electromotive force phase of the grid-forming device matching a grid strength parameter used to represent a grid strength; an amplitude acquisition module configured to acquire an internal electromotive force amplitude of the grid-forming device; a modulation module configured to control the grid-forming device based on the internal electromotive force phase and the internal electromotive force amplitude, so that active power response characteristics of the grid-forming device under different grid strengths are consistent or tend to be consistent.

12. A controller of a network equipment building system, comprising: a processor and a memory storing computer program instructions; the processor executes the computer program instructions to implement the control method of the grid-forming device according to any one of claims 1 to 10.

13. The controller of the network equipment of claim 10, wherein, The controller is arranged in a converter of the grid-forming device.

14. A network equipment building type device comprising: The controller of the grid-forming device according to claim 123. 15.A computer readable storage medium, the computer readable storage medium storing computer program instructions, the computer program instructions being executed by a processor to implement the control method of the grid-forming device according to any one of claims 1 to 10.

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