Converter control method and related product

Abstract

The invention discloses a converter control method and a related product, and relates to the technical field of new energy power generation. Comprising the step of superposing virtual impedance on a control loop of the converter to perform harmonic suppression when at least one of the harmonic quantity of a port output voltage and the harmonic quantity of a port output current is greater than a preset harmonic threshold. And when the electromagnetic torque of the virtual synchronous generator is greater than a preset torque threshold value, reducing the mechanical torque and / or the electromagnetic torque of the virtual synchronous generator so as to reduce the impact current generated by the converter. And when the port voltage is greater than a first preset threshold value or less than a second preset threshold value, correcting the flux linkage of the virtual synchronous generator to obtain a corrected flux linkage so as to provide reactive power support for the power grid during the fault voltage ride-through period. Through the steps, the working stability of the converter is improved by at least two of meeting the power quality requirement of a power grid, improving the inertia response capability and improving the fault voltage ride-through capability.

Description

[0001] This application claims the priority of a domestic application titled "A Converter Control Method and Related Products Based on Virtual Synchronous Generator" with the application number 202311867427.7 filed with the China Patent Office on December 28, 2023. The entire content thereof is incorporated herein by reference. Technical Field

[0002] This application relates to the technical field of new energy power generation, and particularly to a converter control method and related products. Background Art

[0003] A Virtual Synchronous Generator (VSG) is a technology based on advanced synchronous inverter technology and inertial energy storage units, enabling new energy power generation to have the external characteristics of conventional thermal power. It controls the inertial energy storage unit to absorb or release energy by introducing the rotor motion equation into the control algorithm of the grid-connected inverter, simulating the mechanical energy in the rotor of a synchronous generator, so that the virtual synchronous generator has the anti-interference characteristics of a synchronous generator when dealing with disturbances, can effectively improve the inertia and damping levels of the wind power generation system, and thus achieve the friendly grid connection of new energy.

[0004] In related technologies, converters using the virtual synchronous generator control method may have problems of poor working stability, such as difficulty in meeting the grid power quality requirements, poor inertia response ability, or weak fault voltage ride-through ability. Summary of the Invention

[0005] Based on the above problems, this application provides a converter control method and related products to improve the working stability of converters using the virtual synchronous generator control method.

[0006] In a first aspect, an embodiment of this application provides a converter control method. The converter uses virtual synchronous generator technology, and the converter control method includes:

[0007] Obtain at least two variables among the harmonic quantity of the port output voltage of the converter, the harmonic quantity of the port output current of the converter, the electromagnetic torque of the virtual synchronous generator, and the port voltage of the common point of the converter; wherein, the electromagnetic torque of the virtual synchronous generator is calculated based on the port output voltage and the port output current of the converter;

[0008] When at least one of the harmonic quantity of the port output voltage and the harmonic quantity of the port output current is greater than a preset harmonic threshold, superimpose a virtual impedance on the control loop of the converter to suppress harmonics;

[0009] When the electromagnetic torque of the virtual synchronous generator is greater than a preset torque threshold, reduce the mechanical torque and / or electromagnetic torque of the virtual synchronous generator to reduce the impact current generated by the converter;

[0010] When the port voltage is greater than a first preset threshold or less than a second preset threshold, correct the magnetic flux of the virtual synchronous generator to obtain the corrected magnetic flux, so as to provide reactive power support for the power grid during the fault voltage crossing; the first preset threshold is greater than the second preset threshold, the port voltage being greater than the first preset threshold is used to indicate the occurrence of a high voltage crossing fault, and the port voltage being less than the second preset threshold is used to indicate the occurrence of a low voltage crossing fault.

[0011] In a second aspect, an embodiment of the present application provides a converter control device. The converter adopts virtual synchronous generator technology. The converter control device includes at least two of a harmonic suppression module, an inertia response impact current suppression module, and a fault voltage crossing module; the harmonic suppression module includes a first acquisition unit and a superimposing unit, the inertia response impact current suppression module includes a second acquisition unit and a first correction unit, and the fault voltage crossing module includes a third acquisition unit and a second correction unit;

[0012] The first acquisition unit is configured to acquire at least one of the harmonic quantity of the port output voltage and the harmonic quantity of the port output current of the converter;

[0013] The second acquisition unit is configured to obtain the electromagnetic torque of the virtual synchronous generator according to the port output voltage and the port output current of the converter;

[0014] The third acquisition unit is configured to acquire the port voltage of the common point of the converter;

[0015] The superimposing unit is configured to superimpose a virtual impedance on the control loop of the converter when at least one of the harmonic quantity of the port output voltage and the harmonic quantity of the port output current is greater than a preset harmonic threshold, so as to suppress harmonics;

[0016] The first correction unit is configured to reduce the mechanical torque and / or electromagnetic torque of the virtual synchronous generator when the electromagnetic torque of the virtual synchronous generator is greater than a preset torque threshold, so as to reduce the impact current generated by the converter;

[0017] The second correction unit is configured to correct the magnetic flux of the virtual synchronous generator to obtain the corrected magnetic flux when the port voltage is greater than a first preset threshold or less than a second preset threshold, so as to provide reactive power support for the power grid during the fault voltage crossing; the first preset threshold is greater than the second preset threshold, the port voltage being greater than the first preset threshold is used to indicate that a high voltage crossing fault occurs, and the port voltage being less than the second preset threshold is used to indicate that a low voltage crossing fault occurs.

[0018] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned converter control method is implemented.

[0019] In a fourth aspect, an embodiment of the present application provides a control device, which includes: a processor and a memory; a computer program capable of running in the processor is stored on the memory. When the computer program is executed by the processor, the above-mentioned converter control method is implemented.

[0020] In a fifth aspect, an embodiment of the present application provides a converter, which includes the above-mentioned converter control device or the above-mentioned control device.

[0021] In a sixth aspect, an embodiment of the present application provides a new energy power generation system, which includes the above-mentioned converter.

[0022] In a seventh aspect, an embodiment of the present application provides an energy storage system, which includes the above-mentioned converter.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The present application provides a converter control method and related products, which acquire at least two variables among the harmonic content of the port output voltage of the converter, the harmonic content of the port output current, the electromagnetic torque of the virtual synchronous generator, and the port voltage at the common point of the converter. When at least one of the harmonic content of the port output voltage and the harmonic content of the port output current is greater than a preset harmonic threshold, a virtual impedance is superimposed on the control loop of the converter, thereby improving the filtering effect of the filter, that is, correspondingly increasing the equivalent capacitance and / or equivalent inductance of the filter, and further reducing the harmonic content in the port output voltage and the port output current of the converter to meet the requirements of grid power quality. When the electromagnetic torque of the virtual synchronous generator is greater than a preset torque threshold, the mechanical torque and / or electromagnetic torque of the virtual synchronous generator is reduced. By reducing the mechanical torque, the active power reference value can be reduced, so that the virtual synchronous generator has sufficient capacity to provide inertia response support to the grid and reduce the impact current, thereby improving the inertia response ability. Since the electromagnetic torque reflects the port output power of the virtual synchronous generator, when the electromagnetic torque is reduced, the port output power of the virtual synchronous generator can be reduced, and further the impact current can be reduced. When the port voltage is greater than a first preset threshold or less than a second preset threshold, the magnetic flux linkage of the virtual synchronous generator is corrected to obtain the corrected magnetic flux linkage, so as to provide reactive power support to the grid during the fault voltage crossing period. Among them, when the port voltage is greater than the first preset threshold, the corrected magnetic flux linkage increases accordingly, and the output voltage of the converter also increases accordingly, reducing the pressure difference between the port voltage and the output voltage of the converter, and further reducing the port output current of the converter; when the port voltage is less than the second preset threshold, the corrected magnetic flux linkage decreases accordingly, and the output voltage of the converter also decreases accordingly, reducing the pressure difference between the port voltage and the output voltage of the converter, and further reducing the port output current of the converter, avoiding the converter from shutting down due to overcurrent, thereby providing reactive power support to the grid during the fault voltage crossing period and improving the fault voltage crossing ability. Through the above steps, the present application can improve the working stability of the converter using the virtual synchronous generator control method by meeting at least two of the requirements of grid power quality, improving the inertia response ability, and improving the fault voltage crossing ability. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is a flowchart of a converter control method provided by an embodiment of the present application;

[0027] Figure 2 A control block diagram of a new energy power generation system provided by an embodiment of the present application;

[0028] Figure 3 An equivalent circuit diagram of a new energy power generation system provided by an embodiment of the present application; Figure 4 A general block diagram of a converter control based on a virtual synchronous generator provided by an embodiment of the present application;

[0029] Figure 5 A schematic diagram of virtual synchronous generator control in a harmonic suppression method provided by an embodiment of the present application;

[0030] Figure 6 A simplified equivalent circuit diagram of a new energy power generation system provided by an embodiment of the present application;

[0031] Figure 7 A simplified equivalent circuit diagram of a new energy power generation system after control provided by an embodiment of the present application;

[0032] Figure 8 A schematic diagram of virtual synchronous generator control in another harmonic suppression method provided by an embodiment of the present application;

[0033] Figure 9 Another simplified equivalent circuit diagram of a new energy power generation system provided by an embodiment of the present application;

[0034] Figure 10 A schematic diagram of virtual synchronous generator control in yet another harmonic suppression method provided by an embodiment of the present application;

[0035] Figure 11 Yet another simplified equivalent circuit diagram of a new energy power generation system provided by an embodiment of the present application;

[0036] Figure 12 A schematic diagram of virtual synchronous generator control in still another harmonic suppression method provided by an embodiment of the present application;

[0037] Figure 13 Still another simplified equivalent circuit diagram of a new energy power generation system provided by an embodiment of the present application;

[0038] Figure 14 A schematic diagram of virtual synchronous generator control in a harmonic suppression method provided by an embodiment of the present application;

[0039] Figure 15 A simplified equivalent circuit diagram of a new energy power generation system provided by an embodiment of the present application;

[0040] Figure 16 A schematic diagram of a control for reducing mechanical torque provided by an embodiment of the present application;

[0041] Figure 17 Schematic diagram of a control method for reducing magnetic flux provided by an embodiment of the present application;

[0042] Figure 18 Schematic diagram of a control method for rotating electrical angle provided by an embodiment of the present application;

[0043] Figure 19 Schematic diagram of a method for correcting magnetic flux provided by an embodiment of the present application;

[0044] Figure 20 Control block diagram of an energy storage system provided by an embodiment of the present application;

[0045] Figure 21 Control block diagram of a wind power generation system provided by an embodiment of the present application;

[0046] Figure 22 Control block diagram of grid - side fault voltage ride - through of a converter provided by an embodiment of the present application;

[0047] Figure 23 Structural schematic diagram of a converter control device provided by an embodiment of the present application;

[0048] Figure 24 Structural schematic diagram of a control device provided by an embodiment of the present application. Detailed implementation manners

[0049] As described above, a converter adopting the virtual synchronous generator control method may have problems with working stability, such as difficulty in meeting the requirements of grid power quality, poor inertia response ability, or weak fault voltage ride - through ability. Among them, the converter adopts the virtual synchronous generator technology, and the mathematical model of the virtual synchronous generator is as follows:

[0050]

[0051] Among them, in the above formula:

[0052] Angular velocity ω;

[0053] Differential of angular velocity;

[0054] J: Moment of inertia of the virtual synchronous generator;

[0055] T m : Given torque, such as mechanical torque;

[0056] T e : Electromagnetic torque of the virtual synchronous generator;

[0057] D p: Damping coefficient of the virtual synchronous generator;

[0058] M f i f : Flux linkage of the virtual synchronous generator;

[0059] i: Phase current on the grid side of the converter;

[0060] θ: Rotating electrical angle of the virtual synchronous generator;

[0061] Dot product of i and ;

[0062] Dot product of i and ;

[0063] e: Internal electromotive force of the virtual synchronous generator, i.e., VSG voltage;

[0064] Q: Reactive power of the virtual synchronous generator, i.e., VSG reactive power.

[0065] When the above mathematical model is used in the virtual synchronous generator, the converter adopting the virtual synchronous generator control method may have problems with working stability, such as difficulty in meeting the requirements of grid power quality, poor inertia response ability, or weak fault voltage crossing ability.

[0066] To solve the above technical problems, an embodiment of the present application provides a converter control method and related products, which obtain at least two variables among the harmonic quantity of the port output voltage of the converter, the harmonic quantity of the port output current, the electromagnetic torque of the virtual synchronous generator, and the port voltage of the common point of the converter. When at least one of the harmonic quantity of the port output voltage and the harmonic quantity of the port output current is greater than a preset harmonic threshold, a virtual impedance is superimposed on the control loop of the converter, thereby improving the filtering effect of the filter, that is, correspondingly increasing the equivalent capacitance and / or equivalent inductance of the filter, and further reducing the harmonic content in the port output voltage and port output current of the converter to meet the requirements of grid power quality. When the electromagnetic torque of the virtual synchronous generator is greater than a preset torque threshold, the mechanical torque and / or electromagnetic torque of the virtual synchronous generator are reduced. By reducing the mechanical torque, the active power reference value can be reduced, so that the virtual synchronous generator has sufficient capacity to provide inertia response support to the grid and reduce the impact current, improving the inertia response ability. Since the electromagnetic torque reflects the port output power of the virtual synchronous generator, when the electromagnetic torque is reduced, the port output power of the virtual synchronous generator can be reduced, and further the impact current can be reduced. When the port voltage is greater than a first preset threshold or less than a second preset threshold, the magnetic flux linkage of the virtual synchronous generator is corrected to obtain the corrected magnetic flux linkage to provide reactive power support to the grid during the fault voltage crossing period. Among them, when the port voltage is greater than the first preset threshold, the corrected magnetic flux linkage increases accordingly, and the output voltage of the converter also increases accordingly, reducing the voltage difference between the port voltage and the output voltage of the converter, and further reducing the port output current of the converter; when the port voltage is less than the second preset threshold, the corrected magnetic flux linkage decreases accordingly, and the output voltage of the converter also decreases accordingly, reducing the voltage difference between the port voltage and the output voltage of the converter, and further reducing the port output current of the converter, avoiding the converter from shutting down due to overcurrent, thereby providing reactive power support to the grid during the fault voltage crossing period and improving the fault voltage crossing ability. Through the above steps, the present application can improve the working stability of the converter using the virtual synchronous generator control method by meeting at least two of the requirements of grid power quality, improving the inertia response ability, and improving the fault voltage crossing ability.

[0067] To enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0068] See Figure 1 , which is a flowchart of a control method for a virtual synchronous generator provided by an embodiment of the present application.

[0069] As Figure 1 shown, the method includes:

[0070] S101: Obtain at least two variables from among the harmonic quantity of the port output voltage of the converter, the harmonic quantity of the port output current of the converter, the electromagnetic torque of the virtual synchronous generator, and the port voltage at the common point of the converter.

[0071] Among them, the electromagnetic torque of the virtual synchronous generator is calculated based on the port output voltage and the port output current of the converter.

[0072] In the embodiments of the present application, the obtained variable data is at least two, in order to improve the operating stability of the converter adopting the virtual synchronous generator control method from at least two aspects of meeting the requirements of grid power quality, improving the inertia response ability, and improving the fault voltage ride-through ability.

[0073] When obtaining at least two variables from among the harmonic quantity of the port output voltage of the converter, the harmonic quantity of the port output current of the converter, the electromagnetic torque of the virtual synchronous generator, and the port voltage at the common point of the converter, S101 altogether includes the following 4 cases:

[0074] (1) Obtain the harmonic quantity of the port output voltage of the converter and / or the harmonic quantity of the port output current of the converter (that is, obtain at least one of the harmonic quantity of the port output voltage of the converter and the harmonic quantity of the port output current of the converter, including three cases, specifically: only obtain the harmonic quantity of the port output voltage, simultaneously obtain the harmonic quantity of the port output voltage and the harmonic quantity of the port output current, and only obtain the harmonic quantity of the port output current), and obtain the electromagnetic torque of the virtual synchronous generator based on the port output voltage and the port output current of the converter.

[0075] Among them, the port output voltage of the converter is the port voltage of the converter. In the embodiments of the present application, the port voltage of the converter is taken as an example of the port output voltage of the converter for illustration. The port output current of the converter is the port current of the converter. In the embodiments of the present application, the port current of the converter is taken as an example of the port output current of the converter for illustration.

[0076] (2) Obtain the harmonic quantity of the port output voltage of the converter and / or the harmonic quantity of the port output current of the converter, and obtain the port voltage at the common point of the converter.

[0077] (3) Obtain the electromagnetic torque of the virtual synchronous generator based on the port output voltage and the port output current of the converter, and obtain the port voltage at the common point of the converter.

[0078] (4) Obtain the harmonic content of the port output voltage of the converter and / or the harmonic content of the port output current, obtain the electromagnetic torque of the virtual synchronous generator based on the port output voltage and port output current of the converter, and obtain the port voltage at the common point of the converter.

[0079] For ease of understanding, in the subsequent elaboration, the implementation principles of each variable are elaborated separately. Since the total number of variables is 3, they are presented in Embodiments ①-③ respectively. The above (1)-(4) are the corresponding operating condition combinations of ①-③.

[0080] Before specifically explaining Embodiments ①-③, first introduce the application scenarios of the converter in the embodiments of the present application. In the embodiments of the present application, the converter can be applied in a new energy power generation system or an energy storage system. Among them, taking the application of the converter in a new energy power generation system as an example, introduce the operation process of the converter. The control block diagram of the new energy power generation system is as Figure 2 shown.

[0081] The output terminal of the photovoltaic module is connected to one side of the converter after passing through the DC-side capacitor C0, and the other side of the converter is connected to the equivalent power grid through the pre-converter filter inductor L f , the capacitor C f of the filter, and is connected to the equivalent power grid. The equivalent power grid includes the grid equivalent inductor L g and the grid voltage V g . Figure 3 is the equivalent circuit diagram of a new energy power generation system provided by the embodiments of the present application. Among them, I Lf is the input current of the converter, and V s is the output voltage of the converter.

[0082] It should be noted that the input current of the converter is the bridge arm current of the converter. In the embodiments of the present application, the bridge arm current is taken as an example of the input current for illustration.

[0083] At least in the scenarios of new energy power generation systems or energy storage systems, there is a problem that the converter works unstably, and it needs to be improved to meet the requirements of grid power quality, improve the inertia response ability, and improve the fault voltage ride-through ability.

[0084] The specific implementation process is as follows:

[0085] ① Obtain the harmonic content of the port output voltage of the converter and / or the harmonic content of the port output current, that is, obtain at least one of the harmonic content of the port output voltage of the converter and the harmonic content of the port output current.

[0086] In an optional implementation manner, obtain the cut-off frequency of the filter according to the inductor and capacitor of the filter. Taking the LCL filter as an example, the expression of its cut-off frequency is as follows:

[0087]

[0088] Among them, f r is the cut-off frequency, and L g represents the equivalent inductance of the power grid, and L f represents the filter inductance at the front stage of the converter, and C f represents the port capacitance of the converter. It can be seen from the above formula that the cut-off frequency is negatively correlated with the capacitance C f of the filter and the inductance (L g or L f ).

[0089] It should be understood that due to the poor measurability of power grid parameters, it is difficult to detect the power grid impedance in real time and the detection accuracy is not high. In the embodiments of the present application, obtaining the parameters of the filter to calculate the cut-off frequency of the filter is equivalently replaced, that is, detecting the harmonic content of the port output voltage and the harmonic content of the port output current of the converter. Among them, if the impedance between the converter and the grid connection common point is ignored, the port output voltage of the converter is equal to the voltage of the converter at the grid connection common point, that is, V pcc .

[0090] ② Obtain the electromagnetic torque of the virtual synchronous generator according to the port output voltage and the port output current of the converter.

[0091] Since the electromagnetic torque T e responds quickly to load changes, the amplitude of the electromagnetic torque T e is selected as the condition for judging whether the power grid has an inertia response requirement, which can quickly respond to the inertia requirement and then reduce the amplitude of the impact current.

[0092] ③ Obtain the port voltage of the converter common point.

[0093] S102: When at least one of the harmonic content of the port output voltage and the harmonic content of the port output current is greater than a preset harmonic threshold, superimpose a virtual impedance on the control loop of the converter to suppress harmonics; when the electromagnetic torque of the virtual synchronous generator is greater than a preset torque threshold, reduce the mechanical torque and / or electromagnetic torque of the virtual synchronous generator to reduce the impact current generated by the converter; when the port voltage is greater than a first preset threshold or less than a second preset threshold, correct the magnetic flux of the virtual synchronous generator to obtain the corrected magnetic flux to provide reactive power support for the power grid during the fault voltage crossing period; the first preset threshold is greater than the second preset threshold, the port voltage is greater than the first preset threshold, which is used to indicate the occurrence of a high voltage crossing fault, and the port voltage is less than the second preset threshold, which is used to indicate the occurrence of a low voltage crossing fault.

[0094] S102 corresponds to S101. For this purpose, the present application embodiment provides a general control block diagram of a converter based on a virtual synchronous generator, such as Figure 4 As shown. Figure 4 Among them, the inertia response impulse current suppression module is used to improve the inertia response capability of the converter; the harmonic suppression module is used to meet the power quality requirements of the power grid; and the fault voltage ride-through module is used to improve the fault voltage ride-through capability.

[0095] Figure 4 In, P set is the given value of active power, Q set is the reactive power given value, V g is the grid voltage. In actual scenarios, due to V g The output voltage V pcc close, you can pcc As V g Value, ii g is the converter port current, T e is the electromagnetic torque of VSG, T n is the rated torque, M f i f is the VSG magnetic link, T m_fix is the corrected value of the given torque in the inertia response shock suppression module, M f i ffix1 is the value after flux correction in the inertia response shock suppression module, θ fix is the corrected value of the virtual synchronous generator rotation electrical angle in the inertia response impact suppression module, e fix is the converter output voltage V after superimposing virtual impedance s The corrected value, i g_fix is the converter port current i after superimposing the virtual impedance g The corrected value, M f i ffix2 is the corrected magnetic link.

[0096] Among them, the working principle of the harmonic suppression module is: when at least one of the harmonic amount of the port output voltage and the harmonic amount of the port output current is greater than the preset harmonic threshold, a virtual impedance is superimposed on the control loop of the converter to suppress the harmonic amount of the port output voltage and / or the harmonic amount of the port output current.

[0097] The virtual impedance may be a virtual inductor and / or a virtual capacitor. The function of the virtual inductor is the same as that of the real inductor, and the function of the virtual capacitor is the same as that of the real capacitor.

[0098] The method of adding virtual impedance to the control loop through control is more flexible than physically superimposing impedance and can reduce the cost of the system.

[0099] It should be noted that the preset harmonic threshold can be set or modified according to the user's needs.

[0100] In an alternative embodiment, the input current of the converter is differentiated to obtain the voltage of the virtual inductor; the sum of the voltage of the virtual inductor and the original output voltage of the converter is used as the output voltage of the converter, increasing the equivalent inductance of the filter; the equivalent inductance of the filter includes the inductor of the filter and the virtual inductor. It should be understood that the embodiments of the present application are described by taking the LCL filter as an example, where the LCL filter includes the grid equivalent inductance L g , the pre-stage filter inductor L f of the converter, and the converter port capacitor C f .

[0101] As an example, as Figure 5 shown in the control block diagram, the port output voltage V pcc of the converter, the input current I Lf ' (taking the value of the original input current I Lf ), P set , Q set are used as the inputs of the VSG to obtain the output voltage V s of the converter. The input current I Lf ' (taking the value of L If ) of the converter is filtered by the band-pass filter; the input current of the converter after filtering is differentiated by a differentiation link with a differentiation coefficient of L v to obtain the voltage on the virtual inductor L v ; the voltage on the virtual inductor is superimposed on the output voltage V s of the converter to obtain V s '.

[0102] It can be understood that the characteristic frequency of the band-pass filter can be set according to the user's needs. When the characteristic frequency of the band-pass filter is the fundamental frequency, the frequencies of the voltage or current after being filtered by the band-pass filter are all the fundamental frequency, making the parameters more in line with the fundamental characteristics and improving the accuracy of the calculation results.

[0103] Through the above control method, it is equivalent to connecting a virtual inductor L f in series after the pre-stage filter inductor L v of the converter, as Figure 6 shown. The Figure 6 described circuit is equivalently processed to obtain the equivalent circuit diagram as Figure 7 shown. In Figure 7 , L feq is the pre-stage equivalent filter inductor of the converter, C feq is the equivalent capacitor of the converter port, and L geqis the equivalent inductance on the grid side.

[0104] For easier and more intuitive understanding, assume that the grid equivalent inductance L g = 100 uH, the filter inductance L f at the front stage of the converter = 50 uH, the port capacitance C f of the converter = 1200 uF, and the virtual inductance is L v = 100 uH. After the control as shown in Figure 5 , the equivalent filter inductance L feq at the front stage of the converter, the equivalent capacitance C feq of the converter port, and the equivalent inductance L geq on the grid side are as follows:

[0105]

[0106] Since the cut-off frequency f r is negatively correlated with the grid equivalent inductance L g , the filter inductance L f at the front stage of the converter, or the port capacitance C f of the converter. After the control as shown in Figure 5 , the equivalent filter inductance L feq at the front stage of the filter increases, and the cut-off frequency f r decreases to filter out the lower-frequency harmonic content, thereby reducing the harmonic content in the port output voltage and port output current of the converter.

[0107] In an optional implementation, the current of the virtual capacitance is obtained by differentiating the port output voltage of the converter; the difference between the original input current of the converter and the current of the virtual capacitance is used as the input current of the converter to increase the equivalent capacitance of the filter; the equivalent capacitance of the filter includes the capacitance of the filter and the virtual capacitance.

[0108] As an example, for the control block diagram as shown in Figure 8 , the port output voltage V pcc of the converter is filtered by a band-pass filter; the filtered port output voltage of the converter is differentiated through a differentiator with a differentiation coefficient of C v to obtain the current I v on the virtual capacitance C Cv ; the original input current I Lf of the converter is subtracted from the current I Cv on the virtual capacitance to obtain the input current I Lf ' of the converter. Among them, the characteristic frequency of the band-pass filter can be set according to the needs of the user. The output of the VSG is the output voltage V s of the converter, and based on the voltage V s obtain Vs '.

[0109] Through the above control method, it is equivalent to connecting a virtual capacitor C in parallel after the converter port capacitor C f , as shown in v . The circuit described in Figure 9 is equivalently processed to obtain the equivalent circuit diagram shown in Figure 9 . In Figure 7 , L Figure 7 is the equivalent filter inductor at the front stage of the converter, C feq is the equivalent capacitor at the converter port, and L feq is the equivalent inductor on the grid side. geq is the equivalent inductor on the grid side.

[0110] For easier and more intuitive understanding, assume that the grid equivalent inductor L g = 100 uH, the filter inductor L f at the front stage of the converter = 50 uH, the converter port capacitor C f = 1200 uF, the virtual inductor is L v = 0 uH, and the virtual capacitor is C v = 3600 uF. After the control shown in Figure 8 , the equivalent filter inductor L feq at the front stage of the converter, the equivalent capacitor C feq at the converter port, and the equivalent inductor L geq on the grid side are as follows:

[0111]

[0112] Since the cut-off frequency f r is negatively correlated with the grid equivalent inductor L g , the filter inductor L f at the front stage of the converter, or the converter port capacitor C f . After the control shown in Figure 8 , the equivalent capacitor C feq at the converter port of the filter increases, and the cut-off frequency f r decreases to filter out the harmonic content with lower frequencies, thereby reducing the harmonic content in the port output voltage and port output current of the converter.

[0113] In an alternative embodiment, the voltage of the virtual inductor is obtained by differentiating the input current of the converter; the sum of the voltage of the virtual inductor and the original output voltage of the converter is used as the output voltage of the converter to increase the equivalent inductor of the filter; the equivalent inductor of the filter includes the inductor of the filter and the virtual inductor;

[0114] The current of the virtual capacitor is obtained by differentiating the port output voltage of the converter;

[0115] The difference between the original input current of the converter and the current of the virtual capacitor is used as the input current of the converter to increase the equivalent capacitance of the filter; the equivalent capacitance of the filter includes the capacitance of the filter and the virtual capacitor.

[0116] As an example, as Figure 10 shown in the control block diagram, the port output voltage V of the converter pcc is filtered by a band-pass filter; the filtered port output voltage of the converter is differentiated through a differentiating link with a differential coefficient of C v to obtain the current I on the virtual capacitor C v ; the original input current I of the converter Cv is subtracted from the current I on the virtual capacitor Lf to obtain the input current I' of the converter. After the input current I' of the converter is filtered by the band-pass filter; the filtered input current of the converter is differentiated through a differentiating link with a differential coefficient of L Cv to obtain the voltage on the virtual inductor L Lf ; the voltage on the virtual inductor is superimposed on the output voltage V of the converter Lf to obtain V' v . v s s

[0117] It can be understood that the characteristic frequency of the band-pass filter can be set according to the user's needs. When the characteristic frequency of the band-pass filter is the fundamental frequency, the frequencies of the voltage or current filtered by the band-pass filter are all the fundamental frequency, making the parameters more in line with the fundamental characteristics and improving the accuracy of the calculation results. When controlling, if the harmonics are not filtered out, it will interfere with the calculation results.

[0118] Through the above control method, it is equivalent to a virtual capacitor C f being connected in parallel after the converter port capacitor C v , and at the same time a virtual inductor L f being connected in series after the pre-stage filter inductor L of the converter v , as Figure 11 shown. The Figure 11 described circuit is equivalently processed to obtain the equivalent circuit diagram as Figure 7 shown. In Figure 7 , L feq is the equivalent filter inductor at the pre-stage of the converter, C feq is the equivalent capacitor at the converter port, and L geq is the equivalent inductor on the grid side.

[0119] For easier and more intuitive understanding, assume that the grid equivalent inductor L g= 100 uH, the pre-stage filter inductor L of the converter f = 50 uH, the port capacitor C of the converter f = 1200 uF, the virtual inductor is L v = 100 uH, the virtual capacitor is C v = 3600 uF. After the control as shown in Figure 10 the equivalent pre-stage filter inductor L of the converter feq , the equivalent port capacitor C of the converter feq , the equivalent inductor L on the grid side geq is as follows:

[0120]

[0121] Since the cut-off frequency f r has a negative correlation with the equivalent inductor L on the grid g , the pre-stage filter inductor L of the converter f or the port capacitor C of the converter f . After the control as shown in Figure 10 the equivalent pre-stage filter inductor L of the filter increases feq , the equivalent port capacitor C of the filter increases feq , and after the cut-off frequency f r decreases, the harmonic content with lower frequencies can be filtered out, thereby reducing the harmonic content in the port output voltage and port output current of the converter.

[0122] In an alternative embodiment, the derivative of the original input current of the converter is taken to obtain the filter inductor voltage; the derivative of the difference between the port output voltage of the converter and the filter inductor voltage is taken to obtain the current of the virtual capacitor; the difference between the original input current of the converter and the current of the virtual capacitor is used as the input current of the converter to increase the equivalent capacitance of the filter; the equivalent capacitance of the filter includes the capacitance of the filter and the virtual capacitor; the derivative of the input current of the converter is taken to obtain the voltage of the virtual inductor; the sum of the original output voltage of the converter and the voltage of the virtual inductor is used as the output voltage of the converter to increase the equivalent inductance of the filter; the equivalent inductance of the filter includes the inductance of the filter and the virtual inductor.

[0123] As an example, in the control block diagram as shown in Figure 12 , first, the original input current I of the converter is filtered by a band-pass filter Lf , and the filtered input current of the converter is differentiated by a differentiation link with a differentiation coefficient of L f to obtain the voltage on the pre-stage filter inductor L of the converter f ; secondly, the difference between the port output voltage of the converter and the filter inductor voltage, that is, the port output voltage V of the converter, is filtered by a band-pass filterpcc and the voltage difference on the pre-stage filter inductor L f is filtered, and the differential coefficient is C v The differential link of is used to differentiate the difference after filtering to obtain the current I v on the virtual capacitor C Cv ; Again, the original input current I Lf of the converter is subtracted from the current I Cv on the virtual capacitor to obtain the input current I Lf '; Then, I Lf ' is filtered by a band-pass filter, and the differential coefficient is L v The differential link of is used to differentiate I Lf ' after filtering to obtain the voltage on the virtual inductor L v ; Finally, the voltage on the virtual inductor is superimposed on the original output voltage of the converter (the value can be the above output voltage V s ) to obtain V s '. Among them, the characteristic frequency of the band-pass filter can be set according to the user's needs.

[0124] Through the above control method, it is equivalent to a virtual capacitor C f being connected in parallel after the pre-stage filter inductor L v of the converter, and a virtual inductor L f being connected in series after the pre-stage filter inductor L v of the converter, as shown in Figure 13 . The circuit described in Figure 13 is equivalently processed to obtain the equivalent circuit diagram shown in Figure 7 . In Figure 7 , L feq is the equivalent pre-stage filter inductor of the converter, C feq is the equivalent capacitor at the converter port, and L geq is the equivalent inductor on the grid side.

[0125] For easier and more intuitive understanding, assume that the grid equivalent inductor L g = 100 uH, the pre-stage filter inductor L f of the converter = 50 uH, the capacitor C f at the converter port = 1200 uF, the virtual inductor is L v = 100 uH, and the virtual capacitor is C v = 3600 uF. After the control shown in Figure 11 , the equivalent pre-stage filter inductor L feq of the converter, the equivalent capacitor C feq at the converter port, and the equivalent inductor L geq on the grid side are as follows:

[0126]

[0127] Since the cut-off frequency f r and the equivalent inductance L of the power grid g , the pre-stage filter inductance L of the converter f or the port capacitance C of the converter f are negatively correlated. After the control as shown in Figure 12 , the equivalent capacitance C at the converter port of the filter increases, the pre-stage equivalent filter inductance L of the converter increases, the equivalent inductance L on the grid side increases, and the cut-off frequency f feq decreases to filter out the harmonic content with lower frequencies, thereby reducing the harmonic content in the port output voltage and port output current of the converter. feq geq r Lf f f

[0128] In an alternative embodiment, the differential of the original input current of the converter is taken to obtain the filter inductance voltage; the differential of the difference between the port output voltage of the converter and the filter inductance voltage is taken to obtain the current of the virtual capacitor; the difference between the original input current of the converter and the current of the virtual capacitor is used as the input current of the converter to increase the equivalent capacitance of the filter; the equivalent capacitance of the filter includes the capacitance of the filter and the virtual capacitor; the differential of the original input current of the converter is taken to obtain the voltage of the virtual inductor; the sum of the original output voltage of the converter and the voltage of the virtual inductor is used as the output voltage of the converter to increase the equivalent inductance of the filter; the equivalent inductance of the filter includes the inductance of the filter and the virtual inductor.

[0129] As an example, for the control block diagram shown in Figure 14 , first, the original input current I of the converter is filtered by a band-pass filter Lf , and the filtered original input current of the converter is differentiated through a differentiation link with a differentiation coefficient of L f to obtain the voltage across the pre-stage filter inductance L of the converter f ; second, the difference between the port output voltage V of the converter pcc and the voltage across the pre-stage filter inductance L f is filtered by a band-pass filter, and the filtered difference is differentiated through a differentiation link with a differentiation coefficient of C v to obtain the current I v across the virtual capacitor C Cv ; third, the original input current I of the converter Lf is subtracted from the current I Cv across the virtual capacitor to obtain the input current I Lf ′ of the converter; then, the original input current I of the converter is filtered by a band-pass filter LfPerform filtering processing, with a differential coefficient of L v Differentiate the original input current I of the converter after filtering Lf to obtain the voltage across the virtual inductor L v Finally, superimpose the voltage across the virtual inductor on the output voltage V of the converter s to obtain V s '. Among them, the characteristic frequency of the band - pass filter can be set according to the user's needs.

[0130] It should be noted that the band - pass filter in the above - mentioned embodiment can be configured according to the actual situation, and the characteristic frequency of the band - pass filter can be set according to the user's needs.

[0131] Through the above - mentioned control method, it is equivalent to a virtual capacitor C being connected in parallel in front of the pre - stage filter inductor L f of the converter, and a virtual inductor L v being connected in series behind the pre - stage filter inductor L f of the converter, as shown in v Figure 15 Perform equivalent processing on the circuit described above to obtain the equivalent circuit diagram as shown in Figure 15 Figure 7 . In Figure 7 , L feq is the equivalent pre - stage filter inductor of the converter, C feq is the equivalent capacitor at the converter port, and L geq is the equivalent inductor on the grid side.

[0132] For easier and more intuitive understanding, assume that the grid equivalent inductor L g = 100uH, the pre - stage filter inductor L f of the converter = 50uH, the capacitor C f at the converter port = 1200uF, the virtual inductor is L v = 100uH, and the virtual capacitor is C v = 3600uF. After the control as shown in Figure 14 , the equivalent pre - stage filter inductor L feq of the converter, the equivalent capacitor C feq at the converter port, and the equivalent inductor L geq on the grid side are as follows:

[0133]

[0134] Since the cut - off frequency f r is negatively correlated with the grid equivalent inductor L g , the pre - stage filter inductor L f of the converter, or the capacitor C f at the converter port. Through the control as shown in Figure 14 ​​After the control shown, the equivalent capacitance C of the converter port of the filter feq increases, and the equivalent filter inductance L of the front stage of the converter feq increases, and the equivalent inductance L on the grid side geq increases, and the cut-off frequency f r decreases to filter out lower-frequency harmonic content, thereby reducing the harmonic content in the port output voltage and port output current of the converter.

[0135] After any of the above circuit controls, the harmonic content in the port output voltage and port output current of the converter will be reduced, and the degree of reduction is related to the specific circuit structure adopted.

[0136] Inertia response inrush current suppression module - when the electromagnetic torque of the virtual synchronous generator is greater than the preset torque threshold, reduce the mechanical torque and / or electromagnetic torque of the virtual synchronous generator to reduce the inrush current generated by the converter.

[0137] Among them, the preset torque threshold can be set or changed according to the user's needs; the inrush current is the port output current of the converter using the virtual synchronous generator technology during inertia response, that is, the port output current of the converter at the grid connection common point.

[0138] As an example, the preset torque threshold can be equal to the rated torque T n .

[0139] If the preset torque threshold is equal to the rated torque T n , when the electromagnetic torque T e is greater than the rated torque T n , it means that the grid has an inertia response demand and it is necessary to reduce the inrush current generated by the virtual synchronous generator.

[0140] In an optional implementation manner, reduce the mechanical torque T of the virtual synchronous generator m . Specifically, it includes:

[0141] Based on the difference between the electromagnetic torque T e and the rated torque T n , reduce the mechanical torque T of the virtual synchronous generator m to obtain the reduced mechanical torque; where the reduction amount of the mechanical torque is positively correlated with the difference between the electromagnetic torque and the rated torque.

[0142] Specifically, the reference power of the virtual synchronous generator can be reduced based on the initial given power or active power given value P set of the virtual synchronous generator and the reduced mechanical torque T m ′ to improve the capacity of the virtual synchronous generator to provide inertia response support to the grid.

[0143] As an example, reduce the mechanical torque T of the virtual synchronous generator m in the manner as Figure 16 shown. In Figure 16 , P set is the active power setpoint or the initial set power, T e is the electromagnetic torque, T n is the rated torque, T m is the mechanical torque, T m ' is the mechanical torque after correction, and k1 is the torque adjustment coefficient.

[0144] It can be understood that the relationship between the active power setpoint P set and the mechanical torque T m is as follows:

[0145] P set = T m × ω n

[0146] where ω n represents the rotational speed.

[0147] Specifically, the active power setpoint P set divided by the rotational speed ω n yields the mechanical torque T m ; the mechanical torque T e is corrected to obtain T n ' by subtracting k1(T m - T m ). The reduction in the mechanical torque T m is proportional to the difference between the electromagnetic torque T e and the rated torque T n , with the action coefficient being k1. Here, k1 is a constant, and its specific value can be adjusted accordingly according to the magnitude of the inertia response requirement of the power grid.

[0148] There is a positive correlation between the reference power of the virtual synchronous generator and its mechanical torque T m . Reducing the mechanical torque T m is equivalent to reducing the active power reference value or the reference power. Therefore, when the electromagnetic torque T e is greater than the rated torque T n , reducing the mechanical torque T m (equivalent to reducing the active power reference value), the reference power of the virtual synchronous generator decreases, which can increase the capacity of the virtual synchronous generator to provide inertia response support to the power grid, thus leaving enough capacity to meet the inertia response requirement. Here, the capacity can be understood as power.

[0149] It should be noted that the active power setpoint of the virtual synchronous generator is the command value, and the active power reference value is the actual value.

[0150] In an alternative embodiment, the VSG flux M of the virtual synchronous generator is reduced f i f , and the electromagnetic torque T of the virtual synchronous generator is reduced e .

[0151] Specifically, based on the difference between the electromagnetic torque and the rated torque, the flux M of the virtual synchronous generator is reduced f i f , that is, the reduction amount of the flux is positively correlated with the difference between the electromagnetic torque and the rated torque. As Figure 17 shown, in Figure 17 , the flux M f i f is calculated based on the flux constant M f i f0 , k2 is the flux adjustment coefficient, M f i f is the flux of the virtual synchronous generator, and M f i f ′ is the flux of the virtual synchronous generator after correction. Among them, k2 can be set and adjusted according to user needs.

[0152] According to the second formula in the mathematical model of the virtual synchronous generator, when the M of the virtual synchronous generator f i f decreases, it means that the port output power of the virtual synchronous generator decreases; since the port output voltage of the virtual synchronous generator changes slightly, the port output current of the virtual synchronous generator decreases significantly, thereby reducing the impact current generated by the virtual synchronous generator.

[0153] According to the third formula in the mathematical model of the virtual synchronous generator, when the flux M of the virtual synchronous generator is reduced f i f after that, the output voltage of the VSG is also reduced, the voltage on the filter reactance of the converter is reduced, and at the same time, it is beneficial to reduce the electromagnetic torque and further reduce the amplitude of the impact current at the converter port.

[0154] It can be understood that reducing the flux M of the virtual synchronous generator f i f can be used alone to reduce the impact current, or can be used in combination with reducing the mechanical torque T of the virtual synchronous generator m . Generally, limited by the capacity of the virtual synchronous generator, by reducing the mechanical torque T m (equivalent to reducing the active power reference P set)The speed at which the capacity of the virtual synchronous generator is reserved to provide inertia response to the power grid is limited, so the speed of reducing the inrush current is also limited. To accelerate the speed of reducing the inrush current, on the basis of reducing the mechanical torque T m the magnetic flux M M of the virtual synchronous generator can be reduced f i i f to reduce the electromagnetic torque T of the virtual synchronous generator e .

[0155] In an alternative embodiment, based on the difference between the electromagnetic torque and the rated torque, the electrical rotation angle θ of the virtual synchronous generator is reduced to lower the electromagnetic torque T of the virtual synchronous generator e . That is, the reduction amount of the electrical rotation angle is positively correlated with the difference between the electromagnetic torque and the rated torque.

[0156] Reducing the electrical rotation angle θ of the virtual synchronous generator is as shown in Figure 18 . In Figure 18 , θ is the electrical rotation angle before correction, k3 is the angle adjustment coefficient, and θ′ is the electrical rotation angle after correction. Among them, k3 can be set and adjusted according to user requirements.

[0157] Specifically, the electrical rotation angle θ is obtained by integrating the rotational speed ω; θ is corrected to θ′ by subtracting k3(T e -T n ).

[0158] In this embodiment, there are two ways of understanding the reduction of the inrush current amplitude generated by the virtual generator by reducing the electrical rotation angle θ of the virtual generator:

[0159] Firstly, according to the second formula in the data model of the virtual synchronous generator, when the electrical rotation angle θ decreases, it means that the port output power of the virtual synchronous generator decreases; since the port output voltage of the virtual synchronous generator changes slightly, the port output current of the virtual synchronous generator decreases significantly, thereby reducing the inrush current generated by the virtual synchronous generator.

[0160] Secondly, by reducing the electrical rotation angle θ, the system can be quickly switched from one steady state to a new steady state, thereby reducing the inrush current. That is, it accelerates the tracking of the virtual synchronous machine for the mutation phase, enables the virtual synchronous machine to return to a reasonable electrical rotation angle as soon as possible, reduces the inrush current caused by the phase difference, and accelerates its convergence at the same time.

[0161] It can be understood that reducing the electrical rotation angle θ can be arbitrarily combined with reducing the mechanical torque T of the virtual synchronous generator m and / or reducing the magnetic flux M M of the virtual synchronous generator f i i fUsage. Generally, limited by the capacity of the virtual synchronous generator, by reducing the mechanical torque T m The speed of leaving the capacity of the virtual synchronous generator for providing inertia response to the power grid is limited, so the speed of reducing the inrush current is also limited. To accelerate the speed of reducing the inrush current, on the basis of reducing the mechanical torque T m the magnetic flux M of the virtual synchronous generator can be reduced f i f and / or the rotational electrical angle θ can be reduced to reduce the electromagnetic torque T of the virtual synchronous generator e .

[0162] In another implementation, reducing the mechanical torque and electromagnetic torque of the virtual synchronous generator specifically includes:

[0163] Based on the difference between the electromagnetic torque and the rated torque, reducing the mechanical torque of the virtual synchronous generator to obtain the reduced mechanical torque; the reference power of the virtual synchronous generator is positively correlated with the mechanical torque of the virtual synchronous generator; after the reference power of the virtual synchronous generator is reduced, the capacity of the virtual synchronous generator for providing inertia response support to the power grid can be improved;

[0164] Based on the difference between the electromagnetic torque and the rated torque, reducing the magnetic flux of the virtual synchronous generator to reduce the electromagnetic torque of the virtual synchronous generator, or based on the difference between the electromagnetic torque and the rated torque, reducing the rotational electrical angle of the virtual synchronous generator to reduce the electromagnetic torque of the virtual synchronous generator.

[0165] In specific implementation, the implementation processes of reducing the mechanical torque of the virtual synchronous generator, reducing the magnetic flux of the virtual synchronous generator, and reducing the rotational electrical angle of the virtual synchronous generator are as described in the corresponding above content.

[0166] However, in specific reduction, a combination of reducing the mechanical torque of the virtual synchronous generator and reducing the magnetic flux of the virtual synchronous generator can be adopted, or a combination of reducing the mechanical torque of the virtual synchronous generator and reducing the rotational electrical angle of the virtual synchronous generator can be adopted, or a combination of reducing the mechanical torque of the virtual synchronous generator, reducing the magnetic flux of the virtual synchronous generator, and reducing the rotational electrical angle of the virtual synchronous generator can be adopted. The specific reduction degree can be achieved through k1, k2, and k3.

[0167] Fault voltage ride-through module - When the port voltage is greater than the first preset threshold or less than the second preset threshold, the flux linkage is corrected to obtain the corrected flux linkage; the corrected flux linkage is positively correlated with the port voltage at the common point of the converter, and the corrected flux linkage is positively correlated with the port output voltage of the converter; the first preset threshold is greater than the second preset threshold, and the port voltage being greater than the first preset threshold indicates a high voltage ride-through fault, and the port voltage being less than the second preset threshold indicates a low voltage ride-through fault.

[0168] In one implementation, according to Figure 19 the schematic diagram of the corrected flux linkage shown, when the fault voltage flag bit is not enabled, the flux linkage is not corrected (i.e., the correction amount is 0), and when the fault voltage flag bit is enabled, the fault voltage ride-through flux linkage correction module can correct the flux linkage. After the basic flux linkage is corrected by the fault voltage ride-through flux linkage correction module, the corrected flux linkage is obtained, and the expression of the corrected flux linkage is as follows:

[0169] M f i f0 ' = M f i f0 -M f i f0-1 -M f i f0-2

[0170] Among them, M f i f0 ′ is the corrected flux linkage, M f i f0 is the flux linkage constant, M f i f0-1 is the first flux linkage correction amount, M f i f0-2 is the second flux linkage correction amount, specifically as follows:

[0171]

[0172]

[0173] M f i f0-2 = M f i f0 (V pu+ - V FVRTout )K repw+

[0174] Among them, V PCC is the port voltage at the common point of the converter, ω n is the rotational speed, V n is the rated voltage of the converter port, V pu+ is the per-unit value of the positive-sequence component of the converter port voltage; V FVRToutis the fault voltage threshold value, V pu+ is the per-unit value of the positive-sequence voltage at the common point, K repw+ is the reactive power regulation coefficient.

[0175] As can be seen from the above, the corrected flux linkage is positively correlated with the difference between the fault voltage threshold value and the per-unit value of the positive-sequence voltage at the common point. At this time, the converter control method further includes:

[0176] Reducing the port output current of the converter according to the corrected flux linkage.

[0177] According to the first flux linkage correction amount M f i f0-1 According to the expression of, after correcting the flux linkage constant with the first flux linkage correction amount, the corrected flux linkage is positively correlated with the port voltage at the common point of the converter, and there are the following two beneficial effects:

[0178] First, the basic flux linkage can follow the change of the port voltage at the common point of the converter, improve the response speed of the virtual synchronous generator during fault voltage crossing, and quickly enter the fault voltage crossing state.

[0179] Second, when the port voltage is greater than the first preset threshold, the corrected flux linkage increases accordingly, and the output voltage of the converter also increases accordingly, reducing the pressure difference between the port voltage and the output voltage of the converter, and then reducing the port output current of the converter; when the port voltage is less than the second preset threshold, the corrected flux linkage decreases accordingly, and the output voltage of the converter also decreases accordingly, reducing the pressure difference between the port voltage and the output voltage of the converter, and then reducing the port output current of the converter, avoiding the converter from shutting down due to overcurrent.

[0180] According to the second flux linkage correction amount M f i f0-2 According to the expression of, its amplitude is positively correlated with the difference between the fault voltage threshold value and the per-unit value of the positive-sequence voltage at the common point, and reactive power is provided to the power grid according to the corrected flux linkage, specifically as follows:

[0181] When a low-voltage crossing fault occurs, the fault voltage threshold value is equal to 0.9, and the per-unit value of the positive-sequence voltage at the common point is a value less than 0.9. That is, the fault voltage threshold value is greater than the per-unit value of the positive-sequence voltage at the common point. According to the relationship between the flux linkage and the VSG reactive power, at this time, capacitive reactive power is provided to the power grid to support the grid voltage to approach the normal operating voltage.

[0182] When a high-voltage ride-through fault occurs, the fault voltage threshold is equal to 1.1, and the per-unit value of the positive-sequence voltage at the common point is a value greater than 1.1. That is, the fault voltage threshold is less than the per-unit value of the positive-sequence voltage at the common point. According to the relationship between the magnetic flux and the VSG reactive power, it can be known that at this time, inductive reactive power is provided to the power grid to support the power grid voltage to approach the normal operating voltage.

[0183] It can be understood that the correction of the magnetic flux takes time, approximately one fundamental wave period. As an example, one fundamental wave period is 20 ms. That is to say, within this one fundamental wave period, spike pulses will be generated in the grid-side current of the converter, so it is necessary to quickly suppress the spike value of the grid-side current of the converter.

[0184] In a new energy power generation system, when the instantaneous value of the grid-side current of the converter is greater than the corresponding current threshold value output by the grid side of the converter (specifically a current setting value), the switching device of the converter is blocked. Among them, blocking the wave means setting the drive signal of the switching device to zero.

[0185] It should be noted that the blocking time can be determined according to the control loop and response characteristics of the converter; the threshold value can be set or adjusted according to actual needs; the switching device can be a semiconductor switching device, such as IGBT (Insulate-Gate Bipolar Transistor), IGCT (Integrated Gate-Commutated Thyristor), etc.

[0186] Due to the fast response of the blocking process, the switching device after the blocking process is equivalent to a diode in the circuit, and can effectively suppress the spike value of the grid-side current of the converter at the initial stage of the fault voltage ride-through before the correction of the magnetic flux takes effect. In addition, blocking the switching device can also play a role during the entire fault voltage ride-through period, and to a certain extent, suppress the port output current of the converter.

[0187] It should be noted that the 4 cases corresponding to S101 can be freely combined according to at least two of the foregoing Embodiments ①-③, and the beneficial effects after combination are the superposition of the corresponding effects. For example, the beneficial effect of the combined solution of ① and ② is the superposition of the beneficial effect of ① and the beneficial effect of ②.

[0188] In the above embodiments, it is applicable to a new energy power generation system or an energy storage system. Among them, the control block diagram of the new energy power generation system is as Figure 2 shown, and the control block diagram of the energy storage system is as Figure 20As shown. When the above embodiment is applied to a wind power generation system, the fault voltage ride-through control strategy on the grid side of the converter reduces the output current of the converter port. However, for the input current of the converter (the machine side of the converter), no corresponding control is performed, resulting in an increase in the DC bus voltage and a fault exit. The control block diagram of the wind power generation system is as Figure 21 shown. Therefore, in addition to the converter grid side control strategy, the embodiment of the present application also provides a fault voltage ride-through control strategy for the machine side, and its control block diagram is as Figure 22 shown.

[0189] It should be noted that the relevant content of harmonic suppression in the above embodiment is carried out under the condition of a strong power grid, and the relevant content of inertia response and fault voltage ride-through is carried out under the condition of a weak power grid. Among them, the embodiment of the present application does not limit the method of judging the strong power grid condition and the weak power grid condition.

[0190] As Figure 22 shown, the fault voltage ride-through control strategy for the machine side is a double-loop control of the DC bus voltage outer loop and the current inner loop, assisted by a weak magnetic field loop control. In addition, a fault voltage ride-through module is added. When the port voltage is greater than the first preset threshold (a high voltage ride-through fault occurs) or less than the second preset threshold (a low voltage ride-through fault occurs), the fault voltage ride-through module is enabled to improve the active power output capacity of the DC bus during the fault voltage ride-through recovery stage, reduce the drop depth of the DC bus voltage during the fault voltage ride-through recovery stage, and further reduce the amplitude of the impact current caused by the overshoot on the machine side.

[0191] In addition, if the DC bus is equipped with an energy consumption resistor, the overvoltage of the DC bus can be suppressed through the energy consumption resistor. Among them, the energy consumption resistor can be a crowbar resistor Chopper.

[0192] If the DC bus is equipped with energy storage devices, the excess active power input on the machine side of the converter can be absorbed through the energy storage devices to stabilize the DC bus voltage. Among them, the energy storage devices can be batteries or supercapacitors, etc.

[0193] Referring to Figure 23 , the embodiment of the present application also provides a structural schematic diagram of a converter control device.

[0194] As Figure 23 shown, the device includes at least two of a harmonic suppression module 2301, an inertia response impact current suppression module 2302, and a fault voltage ride-through module 2303; the harmonic suppression module 2301 includes a first acquisition unit 23011 and a superposition unit 23012, the inertia response impact current suppression module 2302 includes a second acquisition unit 23021 and a first correction unit 23022, and the fault voltage ride-through module 2303 includes a third acquisition unit 23031 and a second correction unit 23032;

[0195] A first acquisition unit 23011, configured to acquire at least one of a harmonic quantity of a port output voltage of a converter and a harmonic quantity of a port output current;

[0196] A second acquisition unit 23021, configured to obtain an electromagnetic torque of a virtual synchronous generator according to a port output voltage and a port output current of the converter;

[0197] A third acquisition unit 23031, configured to acquire a port voltage of a common point of the converter;

[0198] A superimposing unit 23012, configured to superimpose a virtual impedance on a control loop of the converter to perform harmonic suppression when at least one of the harmonic quantity of the port output voltage and the harmonic quantity of the port output current is greater than a preset harmonic threshold;

[0199] A first correction unit 23022, configured to reduce a mechanical torque and / or an electromagnetic torque of the virtual synchronous generator when the electromagnetic torque of the virtual synchronous generator is greater than a preset threshold, so as to reduce an impact current generated by the converter;

[0200] A second correction unit 23032, configured to correct a magnetic flux of the virtual synchronous generator to obtain a corrected magnetic flux when the port voltage is greater than a first preset threshold or less than a second preset threshold, so as to provide reactive power support for a power grid during a fault voltage ride-through period; the first preset threshold is greater than the second preset threshold, the port voltage being greater than the first preset threshold is used to indicate that a high voltage ride-through fault occurs, and the port voltage being less than the second preset threshold is used to indicate that a low voltage ride-through fault occurs.

[0201] Optionally, the superimposing unit 23012 is specifically configured to:

[0202] Differentiate an input current of the converter to obtain a voltage of a virtual inductor;

[0203] Use a sum of the voltage of the virtual inductor and an original output voltage of the converter as an output voltage of the converter to increase an equivalent inductor of a filter; the equivalent inductor of the filter includes an inductor of the filter and the virtual inductor.

[0204] Optionally, the superimposing unit 23012 is specifically configured to:

[0205] Differentiate a port output voltage of the converter to obtain a current of a virtual capacitor;

[0206] Use a difference between an original input current of the converter and the current of the virtual capacitor as an input current of the converter to increase an equivalent capacitor of a filter; the equivalent capacitor of the filter includes a capacitor of the filter and the virtual capacitor.

[0207] Optionally, the superimposing unit 23012 is specifically configured to:

[0208] Differentiate the original input current of the converter to obtain the filter inductor voltage;

[0209] Differentiate the difference between the port output voltage of the converter and the filter inductor voltage to obtain the current of the virtual capacitor;

[0210] Use the difference between the original input current of the converter and the current of the virtual capacitor as the input current of the converter to increase the equivalent capacitance of the filter; the equivalent capacitance of the filter includes the capacitance of the filter and the virtual capacitor;

[0211] Differentiate the input current of the converter to obtain the voltage of the virtual inductor;

[0212] Use the sum of the original output voltage of the converter and the voltage of the virtual inductor as the output voltage of the converter to increase the equivalent inductance of the filter; the equivalent inductance of the filter includes the inductance of the filter and the virtual inductor.

[0213] Optionally, the superimposing unit 23012 is specifically configured to:

[0214] Differentiate the original input current of the converter to obtain the filter inductor voltage;

[0215] Differentiate the difference between the port output voltage of the converter and the filter inductor voltage to obtain the current of the virtual capacitor;

[0216] Use the difference between the original input current of the converter and the current of the virtual capacitor as the input current of the converter to increase the equivalent capacitance of the filter; the equivalent capacitance of the filter includes the capacitance of the filter and the virtual capacitor;

[0217] Differentiate the original input current of the converter to obtain the voltage of the virtual inductor;

[0218] Use the sum of the original output voltage of the converter and the voltage of the virtual inductor as the output voltage of the converter to increase the equivalent inductance of the filter; the equivalent inductance of the filter includes the inductance of the filter and the virtual inductor.

[0219] Optionally, the harmonic suppression module 2301 further includes: a filtering unit;

[0220] A filtering unit, configured to perform filtering processing on the original input current of the converter, or the input current of the converter, or the port output voltage of the converter, or the difference between the port output voltage of the converter and the filter inductor voltage, through a band-pass filter with a first characteristic frequency, before performing differentiation.

[0221] Optionally, the first correction unit 23022 is specifically configured to:

[0222] Based on the difference between the electromagnetic torque and the rated torque, reduce the mechanical torque of the virtual synchronous generator to obtain a reduced mechanical torque; the reference power of the virtual synchronous generator is positively correlated with the mechanical torque of the virtual synchronous generator; after the reference power of the virtual synchronous generator is reduced, the capacity of the virtual synchronous generator to provide inertia response support to the power grid can be improved.

[0223] Optionally, the first correction unit 23022 is specifically configured to:

[0224] Based on the difference between the electromagnetic torque and the rated torque, reduce the magnetic flux of the virtual synchronous generator to reduce the electromagnetic torque of the virtual synchronous generator;

[0225] Alternatively, based on the difference between the electromagnetic torque and the rated torque, reduce the rotational electrical angle of the virtual synchronous generator to reduce the electromagnetic torque of the virtual synchronous generator.

[0226] Optionally, the first correction unit 23022 is specifically configured to:

[0227] Based on the difference between the electromagnetic torque and the rated torque, reduce the mechanical torque of the virtual synchronous generator to obtain a reduced mechanical torque; the reference power of the virtual synchronous generator is positively correlated with the mechanical torque of the virtual synchronous generator; after the reference power of the virtual synchronous generator is reduced, the capacity of the virtual synchronous generator to provide inertia response support to the power grid can be improved;

[0228] Based on the difference between the electromagnetic torque and the rated torque, reduce the magnetic flux of the virtual synchronous generator to reduce the electromagnetic torque of the virtual synchronous generator, or based on the difference between the electromagnetic torque and the rated torque, reduce the rotational electrical angle of the virtual synchronous generator to reduce the electromagnetic torque of the virtual synchronous generator.

[0229] Optionally, the reduction amount of the mechanical torque, or the reduction amount of the magnetic flux, or the reduction amount of the rotational electrical angle is all positively correlated with the difference between the electromagnetic torque and the rated torque.

[0230] Optionally, the corrected magnetic flux is positively correlated with the port voltage at the common point of the converter and is positively correlated with the port output voltage of the converter.

[0231] Optionally, the fault voltage ride-through module 2303 further includes: a reactive power unit;

[0232] The reactive power unit is configured to provide reactive power to the power grid according to the corrected magnetic flux.

[0233] Optionally, the reactive power unit is specifically configured to:

[0234] When the fault voltage threshold value is greater than the per-unit value of the positive-sequence voltage at the common point, provide capacitive reactive power to the power grid;

[0235] When the fault voltage threshold value is less than the per-unit value of the positive-sequence voltage at the common point, provide inductive reactive power to the power grid.

[0236] Figure 24 is a block diagram showing a control device according to an embodiment of the present application. The control device can implement the control of the converter of a new energy generating set or the converter of a grid-connected energy storage device, or be implemented as other controls in a new energy generating set or a grid-connected energy storage device. Among them, the new energy generating set includes a wind generating set and / or a photovoltaic generating set.

[0237] Referring to Figure 24 , the control device 2400 according to an embodiment of the present disclosure may include a processor 2410 and a memory 2420. The processor 2410 may include (but is not limited to) a central processing unit (CPU), a digital signal processor (DSP), a microcomputer, a field programmable gate array (FPGA), a system on chip (SoC), a microprocessor, an application specific integrated circuit (ASIC), etc. The memory 2420 stores a computer program to be executed by the processor 2410. The memory 2420 includes a high-speed random access memory and / or a non-volatile computer-readable storage medium. When the processor 2410 executes the computer program stored in the memory 2420, the control method of the converter as described above can be implemented.

[0238] Optionally, the control device 2400 can communicate with each component in the new energy generating set or the grid-connected energy storage device in a wired / wireless communication manner, and can also communicate with devices external to the new energy generating set or the grid-connected energy storage device in a wired / wireless communication manner.

[0239] In addition, an embodiment of the present application further provides a converter, which includes the foregoing converter control device or the foregoing control device.

[0240] The control method of the converter according to the embodiments of the present application can be written as a computer program and stored on a computer-readable storage medium. When the computer program is executed by a processor, the control method of the converter as described above can be implemented. Examples of computer-readable storage media include: read-only memory (ROM), random access programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, non-volatile memory, CD-ROM, CD-R, CD+R, CD-RW, CD+RW, DVD-ROM, DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM, BD-ROM, BD-R, BD-R LTH, BD-RE, Blu-ray or optical disc memory, hard disk drive (HDD), solid state drive (SSD), cartridge memory (such as, multimedia card, secure digital (SD) card or extreme digital (XD) card), magnetic tape, floppy disk, magneto-optical data storage device, optical data storage device, hard disk, solid state disk and any other device, any other device being configured to store the computer program and any associated data, data files and data structures in a non-transitory manner and provide the computer program and any associated data, data files and data structures to a processor or computer such that the processor or computer can execute the computer program. In one example, the computer program and any associated data, data files and data structures are distributed across a networked computer system such that the computer program and any associated data, data files and data structures are stored, accessed and executed in a distributed manner by one or more processors or computers.

[0241] In addition, the embodiments of the present application further provide a new energy power generation system, which includes the aforementioned converter. In addition, the new energy power generation system further includes a new energy power generation set, and the new energy power generation set is connected to the power grid through the converter.

[0242] It should be understood that the new energy power generation set includes, but is not limited to, a wind power generation set and a photovoltaic power generation set.

[0243] In one implementation, the converter is further configured to:

[0244] When the instantaneous value of the grid-side current of the converter is greater than the current threshold value output by the grid side of the converter, the switching device of the converter is blocked from wave. For the specific implementation process, refer to the corresponding description above.

[0245] In one implementation, when the new energy power generation system is a wind power generation system, the converter is further configured to:

[0246] Maintain the active power output by the machine-side current loop of the converter.

[0247] Specifically, as Figure 22 shown, the fault voltage ride-through control strategy on the machine side is a double-loop control of the DC bus voltage outer loop and the current inner loop, supplemented by a field-weakening loop control. In addition, a fault voltage ride-through module is added. When the port voltage is greater than the first preset threshold (high voltage ride-through fault occurs) or less than the second preset threshold (low voltage ride-through fault occurs), the fault voltage ride-through module is enabled to improve the active power output capacity of the DC bus during the fault voltage ride-through recovery stage, reduce the voltage drop depth of the DC bus during the fault voltage ride-through recovery stage, and further reduce the amplitude of the impact current caused by the overshoot on the machine side.

[0248] In one implementation, an energy consumption resistor is configured on the DC bus of the wind power generation system, and the converter is further configured to:

[0249] Suppress the overvoltage of the DC bus according to the energy consumption resistor;

[0250] Specifically, if the DC bus is equipped with an energy consumption resistor, the overvoltage of the DC bus can be suppressed by the energy consumption resistor. Among them, the energy consumption resistor can be a crowbar resistor Chopper.

[0251] In one implementation, a energy storage device is configured on the DC bus of the wind power generation system, and the converter is further configured to:

[0252] Absorb the active power output from the machine side of the converter according to the energy storage device.

[0253] Specifically, if the DC bus is equipped with an energy storage device, the redundant active power input from the machine side of the converter can be absorbed by the energy storage device to stabilize the DC bus voltage. Among them, the energy storage device can be a battery or a super capacitor, etc.

[0254] The embodiment of the present application further provides an energy storage system, which includes the aforementioned converter, and may further include a grid-connected energy storage device. The grid-connected energy storage device is connected to the grid through the converter. Among them, the grid-connected energy storage device refers to an energy storage device with grid-connected function, which can support the smooth operation of the grid, help regulate the grid frequency and voltage, and improve the stability and reliability of the grid.

[0255] For the converter of the new energy power generation system or the energy storage system according to the embodiment of the present application, by correcting the mechanical torque and / or electromagnetic torque of the virtual synchronous generator in the converter, the over-current of the inertia response under the heavy-load output condition of the converter can be effectively reduced, ensuring the normal operation of the converter adopting the virtual synchronous generator technology, and at the same time meeting the requirement of the converter to support the grid to provide fast and necessary inertia response.

[0256] It should be noted that the embodiments in this specification are all described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the key points of each embodiment are the differences from other embodiments. In particular, for the apparatus embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and for the relevant parts, reference can be made to the description of the method embodiments. The apparatus embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components referred to as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without creative work.

[0257] As described above, it is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A converter control method, characterized in that: The converter adopts virtual synchronous generator technology, and the converter control method includes: Obtain at least one of the harmonic amount of the port output voltage and the harmonic amount of the port output current of the converter, the electromagnetic torque of the virtual synchronous generator, and at least two variables of the port voltage of the common point of the converter; wherein the electromagnetic torque of the virtual synchronous generator is calculated according to the port output voltage and the port output current of the converter; When at least one of the harmonic amount of the port output voltage and the harmonic amount of the port output current is greater than a preset harmonic threshold, superimposing a virtual impedance on the control loop of the converter to perform harmonic suppression; When the electromagnetic torque of the virtual synchronous generator is greater than a preset torque threshold, reducing the mechanical torque and / or electromagnetic torque of the virtual synchronous generator to reduce the impact current generated by the converter; When the port voltage is greater than a first preset threshold or less than a second preset threshold, the flux of the virtual synchronous generator is corrected to obtain a corrected flux to provide reactive support for the power grid during fault voltage ride-through; the first preset threshold is greater than the second preset threshold, and the port voltage is greater than the first preset threshold, which is used to indicate a high voltage ride-through fault; the port voltage is less than the second preset threshold, which is used to indicate a low voltage ride-through fault.

2. The converter control method according to claim 1, characterized in that: The step of superimposing a virtual impedance on the control loop of the converter specifically includes: Differentiating the input current of the converter to obtain a voltage of the virtual inductor; The sum of the voltage of the virtual inductor and the original output voltage of the converter is used as the output voltage of the converter to increase the equivalent inductance of the filter; the equivalent inductance of the filter includes the inductance of the filter and the virtual inductor.

3. The converter control method according to claim 1 or 2, characterized in that: The step of superimposing a virtual impedance on the control loop of the converter specifically includes: Differentiating the port output voltage of the converter to obtain the current of the virtual capacitor; The difference between the original input current of the converter and the current of the virtual capacitor is used as the input current of the converter to increase the equivalent capacitance of the filter; the equivalent capacitance of the filter includes the capacitance of the filter and the virtual capacitance.

4. The converter control method according to claim 1, characterized in that: The step of superimposing a virtual impedance on the control loop of the converter specifically includes: Differentiating the original input current of the converter to obtain a filter inductor voltage; Differentiating the difference between the port output voltage of the converter and the filter inductor voltage to obtain the current of the virtual capacitor; The difference between the original input current of the converter and the current of the virtual capacitor is used as the input current of the converter to increase the equivalent capacitance of the filter; the equivalent capacitance of the filter includes the capacitance of the filter and the virtual capacitance; Differentiating the input current of the converter to obtain a voltage of the virtual inductor; The sum of the original output voltage of the converter and the voltage of the virtual inductor is used as the output voltage of the converter to increase the equivalent inductance of the filter; the equivalent inductance of the filter includes the inductance of the filter and the virtual inductor.

5. The converter control method according to claim 1, characterized in that: The step of superimposing a virtual impedance on the control loop of the converter specifically includes: Differentiating the original input current of the converter to obtain a filter inductor voltage; Differentiating the difference between the port output voltage of the converter and the filter inductor voltage to obtain the current of the virtual capacitor; The difference between the original input current of the converter and the current of the virtual capacitor is used as the input current of the converter to increase the equivalent capacitance of the filter; the equivalent capacitance of the filter includes the capacitance of the filter and the virtual capacitance; Differentiating the original input current of the converter to obtain the voltage of the virtual inductor; The sum of the original output voltage of the converter and the voltage of the virtual inductor is used as the output voltage of the converter to increase the equivalent inductance of the filter; the equivalent inductance of the filter includes the inductance of the filter and the virtual inductor.

6. The converter control method according to any one of claims 2 to 5, characterized in that: The method further comprises: Before differentiation, the original input current of the converter, or the input current of the converter, or the port output voltage of the converter, or the difference between the port output voltage of the converter and the filter inductor voltage is filtered through a bandpass filter of a first characteristic frequency.

7. The converter control method according to claim 1, characterized in that: The reducing the mechanical torque of the virtual synchronous generator specifically includes: Based on the difference between the electromagnetic torque and the rated torque, the mechanical torque of the virtual synchronous generator is reduced to obtain the reduced mechanical torque; the reference power of the virtual synchronous generator is positively correlated with the mechanical torque of the virtual synchronous generator; after the reference power of the virtual synchronous generator is reduced, the capacity of the virtual synchronous generator for providing inertia response support to the power grid can be increased.

8. The converter control method according to claim 1, characterized in that: The reducing the electromagnetic torque of the virtual synchronous generator specifically includes: Based on the difference between the electromagnetic torque and the rated torque, the magnetic flux of the virtual synchronous generator is reduced to reduce the electromagnetic torque of the virtual synchronous generator; Alternatively, based on the difference between the electromagnetic torque and the rated torque, the rotation electrical angle of the virtual synchronous generator is reduced to reduce the electromagnetic torque of the virtual synchronous generator.

9. The converter control method according to claim 1, characterized in that: Reducing the mechanical torque and electromagnetic torque of the virtual synchronous generator specifically includes: Based on the difference between the electromagnetic torque and the rated torque, the mechanical torque of the virtual synchronous generator is reduced to obtain the reduced mechanical torque; the reference power of the virtual synchronous generator is positively correlated with the mechanical torque of the virtual synchronous generator; after the reference power of the virtual synchronous generator is reduced, the capacity of the virtual synchronous generator for providing inertia response support to the power grid can be increased; Based on the difference between the electromagnetic torque and the rated torque, the magnetic flux of the virtual synchronous generator is reduced to reduce the electromagnetic torque of the virtual synchronous generator; or, based on the difference between the electromagnetic torque and the rated torque, the rotation electrical angle of the virtual synchronous generator is reduced to reduce the electromagnetic torque of the virtual synchronous generator.

10. The converter control method according to any one of claims 7 to 9, characterized in that: The reduction amount of the mechanical torque, the reduction amount of the magnetic flux, or the reduction amount of the rotational electrical angle is positively correlated with the difference between the electromagnetic torque and the rated torque.

11. The converter control method according to claim 1, characterized in that: The corrected flux linkage is positively correlated with the port voltage of the common point of the converter, and the corrected flux linkage is positively correlated with the port output voltage of the converter.

12. The converter control method according to claim 1, characterized in that: The corrected flux linkage is positively correlated with the difference between the fault voltage threshold value and the per-unit value of the common point positive sequence voltage, and the method further includes: Reactive power is provided to the power grid according to the corrected flux linkage.

13. The converter control method according to claim 12, characterized in that: The providing reactive power to the power grid according to the corrected magnetic flux specifically includes: When the fault voltage threshold value is greater than the per-unit value of the common point positive sequence voltage, providing capacitive reactive power to the power grid; When the fault voltage threshold value is less than the per-unit value of the common point positive sequence voltage, inductive reactive power is provided to the power grid.

14. A converter control device, characterized in that: The converter adopts virtual synchronous generator technology, and the converter control device includes: at least two of a harmonic suppression module, an inertia response impulse current suppression module and a fault voltage ride-through module; the harmonic suppression module includes a first acquisition unit and a superposition unit, the inertia response impulse current suppression module includes a second acquisition unit and a first correction unit, and the fault voltage ride-through module includes a third acquisition unit and a second correction unit; The first acquisition unit is used to acquire at least one of the harmonic amount of the port output voltage and the harmonic amount of the port output current of the converter; The second acquisition unit is used to obtain the electromagnetic torque of the virtual synchronous generator according to the port output voltage and the port output current of the converter; The third acquisition unit is used to acquire the port voltage of the common point of the converter; The superposition unit is used to superimpose a virtual impedance on the control loop of the converter to perform harmonic suppression when at least one of the harmonic amount of the port output voltage and the harmonic amount of the port output current is greater than a preset harmonic threshold; The first correction unit is used to reduce the mechanical torque and / or electromagnetic torque of the virtual synchronous generator when the electromagnetic torque of the virtual synchronous generator is greater than a preset torque threshold, so as to reduce the impact current generated by the converter; The second correction unit is used to correct the flux of the virtual synchronous generator to obtain a corrected flux when the port voltage is greater than a first preset threshold or less than a second preset threshold, so as to provide reactive support for the power grid during fault voltage ride-through; the first preset threshold is greater than the second preset threshold, and the port voltage is greater than the first preset threshold, which is used to indicate a high voltage ride-through fault; the port voltage is less than the second preset threshold, which is used to indicate a low voltage ride-through fault.

15. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, the converter control method as described in any one of claims 1 to 13 is implemented.

16. A control device, characterized in that: The control device comprises: a processor and a memory; a computer program executable in the processor is stored in the memory, and when the computer program is executed by the processor, the converter control method as described in any one of claims 1 to 13 is implemented.

17. A converter, characterized in that: The converter comprises the converter control device according to claim 14 or the control apparatus according to claim 16.

18. A new energy power generation system, characterized in that: The new energy power generation system includes the converter as claimed in claim 17.

19. The new energy power generation system according to claim 18, characterized in that: The converter is also used for: When the instantaneous value of the grid-side current of the converter is greater than the current threshold value of the grid-side output of the converter, the switching device of the converter is blocked.

20. The new energy power generation system according to claim 18, characterized in that: When the new energy power generation system is a wind power generation system, the converter is also used for: Maintain the active power output by the machine-side current loop of the converter.

21. The new energy power generation system according to claim 20, characterized in that: The DC bus of the wind power generation system is equipped with an energy consumption resistor, and the converter is also used for: suppressing overvoltage of the DC bus according to the energy consumption resistor; Alternatively, the DC bus of the wind power generation system is configured with an energy storage device, and the converter is further used for: The active power outputted from the machine side of the converter is absorbed according to the energy storage device.

22. An energy storage system, characterized in that: The energy storage system comprises the converter as claimed in claim 17.

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