Control method and device for inertia support of grid-connected converter

Abstract

The invention discloses a grid-connected converter inertia support control method and device, and relates to the technical field of new energy power generation. The control method for inertia support of the grid-connected converter comprises the following steps: acquiring a target real-time frequency value of the grid-connected converter, wherein the target real-time frequency value comprises at least one of a real-time frequency value of an alternating-current side voltage and a real-time frequency value of a grid-connected point voltage; determining a frequency feed-forward quantity according to the target real-time frequency value; according to the frequency feed-forward quantity, a target phase angle is determined, and the target phase angle is used for adjusting the output phase of the grid-connected converter so that the output phase and the phase of the power grid can be kept synchronous. According to the embodiment of the invention, the method not only can improve the operation stability of a power system, but also can meet the requirements of inertia support on three performance indexes, namely response speed, overshoot and inertia time constant.

Description

Technical Field

[0001] The present application belongs to the field of renewable energy power generation technology, and specifically relates to a control method and device for inertia support of a grid-connected converter. Background Art

[0002] With the increasing proportion of renewable energy generation, the traditional power system dominated by mechanical electromagnetics is transforming into a new power system with a high proportion of power electronic equipment. The system inertia no longer grows with the scale and even shows a downward trend, resulting in weak active power support capability, threatening the stable control of grid frequency. In response to this, grid-type control technology with inertia support capability and its converter system are gradually gaining attention.

[0003] The grid-connected converter is connected to the grid with a voltage source. Existing control technologies such as virtual synchronous machine control and inertia droop control, in which the active power control link realizes the primary frequency modulation and inertia support functions at the same time, use two control parameters. Specifically, the two control parameters of the virtual synchronous machine control are the damping coefficient and the rotational inertia coefficient; the two control parameters of the inertia droop control are the droop coefficient and the first-order filter cutoff frequency. Among them, the damping coefficient and the droop coefficient are determined by the active frequency modulation coefficient under the primary frequency modulation function, and the rotational inertia coefficient and the first-order filter cutoff frequency are determined by the inertia time constant under the inertia support function.

[0004] The active power control link of the grid-connected converter is a second-order control system, and the system damping ratio decreases with the increase of the active frequency modulation coefficient and the inertia time constant. When the active frequency modulation coefficient and the inertia time constant both require large values, the system will enter an under-damped state with extremely low damping. Combined with the delay of the digital control system of the system, the stability is further weakened and it is easy to exceed the stable operation boundary. In addition, the existing grid-connected technology has only two control parameters, which cannot simultaneously meet the three performance index requirements of inertia support in response speed, overshoot and inertia time constant. Summary of the invention

[0005] The technical problem to be solved by the present application is to provide a control method and device for the inertia support of a grid-connected converter in view of the above-mentioned deficiencies in the prior art. The method can not only improve the stability of the operation of the power system, but also simultaneously meet the three performance index requirements of the inertia support in terms of response speed, overshoot and inertia time constant.

[0006] In a first aspect, an embodiment of the present application provides a method for controlling an inertia support of a grid-connected converter, comprising:

[0007] Acquire a target real-time frequency value of the grid-connected converter, where the target real-time frequency value includes at least one of a real-time frequency value of the AC side voltage and a real-time frequency value of the grid-connected point voltage;

[0008] Determine the frequency feedforward amount according to the target real-time frequency value;

[0009] The target phase angle is determined according to the frequency feedforward amount, and the target phase angle is used to adjust the output phase of the grid-connected converter so that the output phase is synchronized with the phase of the power grid.

[0010] In some implementations of the first aspect, determining the frequency feedforward amount according to the target real-time frequency value includes:

[0011] Determine the output signal type of the grid-connected converter according to the target real-time frequency value;

[0012] Determine the frequency feedforward amount based on the output signal type.

[0013] In some implementations of the first aspect, the output signal type includes a reset signal and an enable signal, and determining the output signal type of the grid-connected converter according to the target real-time frequency value includes:

[0014] When the target real-time frequency value satisfies the first preset condition, determining that the output signal type of the grid-connected converter is a reset signal;

[0015] When the target real-time frequency value satisfies the second preset condition, determining that the output signal type of the grid-connected converter is an enable signal;

[0016] Among them, the first preset condition includes ω1≤ω g ≤ω2、ω g >ω4 and ω g < any one of ω3; ω g Indicates the target real-time frequency value, ω1 indicates the lower limit of the frequency dead zone required by the inertia response, ω2 indicates the upper limit of the frequency dead zone required by the inertia response, ω3 indicates the lower limit of the frequency range of the inertia response, and ω4 indicates the upper limit of the frequency range of the inertia response;

[0017] The second preset condition includes ω3≤ω g <ω1 and ω4>ω g > any one of ω2.

[0018] In some implementations of the first aspect, the output signal type includes a reset signal and an enable signal, and determining the frequency feedforward amount according to the output signal type includes:

[0019] When the output signal type includes a reset signal, the target real-time frequency value is substituted into formula (1) to calculate and obtain the frequency feedforward value;

[0020] Formula (1) includes:

[0021] ω0=ω g (1)

[0022] Among them, ω0 represents the frequency feedforward; ω g Indicates the target real-time frequency value;

[0023] Alternatively, when the output signal type includes an enable signal, the target real-time frequency value and the gain of the target filter are substituted into formula (2) for calculation to obtain the frequency feedforward value;

[0024] Formula (2) includes:

[0025] ω0=F(s)ω g (2)

[0026] Where F(s) represents the gain of the target filter.

[0027] In some implementations of the first aspect, the target filter comprises a first-order filter, and the gain of the target filter comprises a first gain of the first-order filter;

[0028] Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward value, the method further includes:

[0029] Acquire the operation factor and the first parameter corresponding to the first-order filter, the first parameter including the first active frequency modulation coefficient and the first inertia time constant;

[0030] Substitute the first active frequency modulation coefficient and the first inertia time constant into formula (3) to calculate and obtain the first cut-off frequency;

[0031] Formula (3) includes:

[0032]

[0033] Among them, ω J1 represents the first cutoff frequency; k f1 Indicates the first active frequency modulation coefficient; T1 J represents the first inertia time constant;

[0034] Substitute the operation factor and the first cutoff frequency into formula (4) to calculate and obtain the first gain;

[0035] Formula (4) includes:

[0036]

[0037] Wherein, s represents the operation factor; F1(s) represents the first gain;

[0038] Formula (2) includes formula (21). Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation, the frequency feedforward amount is obtained, including:

[0039] Substitute the target real-time frequency value and the first gain into formula (21) to calculate and obtain the frequency feedforward value;

[0040] Among them, formula (21) includes:

[0041] ω0=f1(s)ω g (twenty one).

[0042] In some embodiments of the first aspect, the target filter comprises a second-order filter, and the gain of the target filter comprises a second gain of the second-order filter;

[0043] Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward value, the method further includes:

[0044] Obtaining the operation factor and the second parameter corresponding to the second-order filter, the second parameter including the second active frequency modulation coefficient, the system rated power, the damping ratio and the second inertia time constant;

[0045] Substituting the second active frequency modulation coefficient, the first system rated power, the first damping ratio and the second inertia time constant into formula (5) for calculation, the second cut-off frequency is obtained;

[0046] Formula (5) includes:

[0047]

[0048] Among them, ω J2 represents the second cutoff frequency; k f2 Indicates the second active frequency modulation coefficient; T2 J represents the second inertia time constant; ξ represents the damping ratio; F g Indicates the system rated power;

[0049] Substitute the second cutoff frequency, the operation factor and the damping ratio into formula (6) to calculate and obtain the second gain;

[0050] Formula (6) includes:

[0051]

[0052] Wherein, s represents the operation factor; f2(s) represents the second gain;

[0053] Formula (2) includes formula (22). Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation, the frequency feedforward amount is obtained, including:

[0054] Substitute the target real-time frequency value and the second gain into formula (22) to calculate and obtain the frequency feedforward value;

[0055] Among them, formula (22) includes:

[0056] ω0=F2(s)ω g (twenty two).

[0057] In some implementations of the first aspect, the target filter includes an N-order filter, the gain of the target filter includes a third gain of the N-order filter, and N is an integer greater than or equal to 3;

[0058] Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward value, the method further includes:

[0059] Decomposing the third inertia time constant of the N-order filter into m first inertia time constants and n second inertia time constants, the first inertia time constant is the inertia time constant corresponding to the first-order filter, the second inertia time constant is the inertia time constant corresponding to the second-order filter, and m and n are both integers;

[0060] Obtaining a first gain corresponding to each of the m first inertia time constants and a second gain corresponding to each of the n second inertia time constants;

[0061] Substituting all the first gains and all the second gains into formula (7) for calculation, a third gain is obtained;

[0062] Formula (7) includes:

[0063] F3(s)=F 11 (s)F 12 (s)…F 1m (s)F 21 (s)F 22 (s)…F 2n (s) (7)

[0064] Wherein, F3(s) represents the third gain; F 11 (s) represents the first gain corresponding to the first inertia time constant; F 12 (s) represents the first gain corresponding to the second first inertia time constant; F 1m (s) represents the first gain corresponding to the mth first inertia time constant; F 21 (s) represents the second gain corresponding to the second inertia time constant; F 22 (s) represents the second gain corresponding to the second inertia time constant; F 2m (s) represents the second gain corresponding to the mth second inertia time constant;

[0065] Formula (2) includes formula (23). Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation, the frequency feedforward amount is obtained, including:

[0066] Substitute the target real-time frequency value and the third gain into formula (23) to calculate and obtain the frequency feedforward value;

[0067] Among them, formula (23) includes:

[0068] ω0=F3(s)ω g (twenty three).

[0069] In some implementations of the first aspect, obtaining the target real-time frequency value includes:

[0070] Obtaining a target voltage, where the target voltage includes at least one of an AC side voltage and a grid connection point voltage, and the target voltage corresponds to a target real-time frequency value;

[0071] According to the target voltage, determine the target real-time frequency value;

[0072] Alternatively, the target real-time frequency value is obtained in real time from a frequency measuring device;

[0073] Alternatively, the real-time frequency value of the AC side voltage and / or the grid connection point voltage in the upper level or the same line power system is used as the target real-time frequency value.

[0074] Based on the same inventive concept, in a second aspect, an embodiment of the present application further provides a control device for inertia support of a grid-connected converter, comprising:

[0075] A first acquisition module is used to acquire a target real-time frequency value of the grid-connected converter, where the target real-time frequency value includes at least one of a real-time frequency value of the AC side voltage and a real-time frequency value of the grid-connected point voltage;

[0076] A first determination module, connected to the first acquisition module, is used to determine a frequency feedforward amount according to a target real-time frequency value;

[0077] The second determination module is connected to the first determination module and is used to determine a target phase angle according to the frequency feedforward amount. The target phase angle is used to adjust the output phase of the grid-connected converter so that the output phase is synchronized with the phase of the power grid.

[0078] In some implementations of the second aspect, the first determining module includes:

[0079] A first determination submodule, used to determine the output signal type of the grid-connected converter according to the target real-time frequency value;

[0080] The second determining submodule is connected to the first determining submodule and is used to determine the frequency feedforward amount according to the output signal type.

[0081] In some implementations of the second aspect, the output signal type includes a reset signal and an enable signal, and the first determination submodule includes:

[0082] A first determining unit, configured to determine that the output signal type of the grid-connected converter is a reset signal when the target real-time frequency value satisfies a first preset condition;

[0083] A second determining unit, configured to determine that the output signal type of the grid-connected converter is an enabling signal when the target real-time frequency value satisfies a second preset condition;

[0084] Among them, the first preset condition includes ω1≤η g ≤ω2、η g >ω4 and ω g < any one of ω3; ω g Indicates the target real-time frequency value, ω1 indicates the lower limit of the frequency dead zone required by the inertia response, ω2 indicates the upper limit of the frequency dead zone required by the inertia response, ω3 indicates the lower limit of the frequency range of the inertia response, and ω4 indicates the upper limit of the frequency range of the inertia response;

[0085] The second preset condition includes ω3≤ω g <ω1 and ω4>ω g > any one of ω2.

[0086] In some implementations of the second aspect, the output signal type includes a reset signal and an enable signal, and the second determination submodule includes:

[0087] A first calculation unit is used for substituting the target real-time frequency value into formula (1) for calculation to obtain a frequency feedforward value when the output signal type includes a reset signal;

[0088] Formula (1) includes:

[0089] ω0=ω g (1)

[0090] Among them, ω0 represents the frequency feedforward; ω g Indicates the target real-time frequency value;

[0091] Alternatively, the second calculation unit is used to substitute the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward amount when the output signal type includes an enable signal;

[0092] Formula (2) includes:

[0093] ω0=F(s)ω g (2)

[0094] Where F(s) represents the gain of the target filter.

[0095] According to the control method and device of the inertial support of the grid-connected converter provided in the embodiment of the present application, on the one hand, the frequency feedforward amount is determined by the target real-time frequency value, and then the target phase angle can be determined according to the frequency feedforward amount, so as to adjust the output phase of the grid-connected converter by the target phase angle, so that the output phase of the grid-connected converter is synchronized with the phase of the power grid, which can improve the stability of the operation of the power system; on the other hand, compared with the existing networking technology with only two control parameters, the embodiment of the present application adds the control parameter of the frequency feedforward amount to adjust the active power, and combines the existing damping coefficient and rotational inertia coefficient, or the droop coefficient and the first-order filter cutoff frequency, so as to independently design and implement the response speed, overshoot and inertia time constant, that is, it can simultaneously meet the three performance index requirements of the inertia support in terms of response speed, overshoot and inertia time constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Figure 1 A schematic diagram showing a main circuit topology and a grid-connected control system of a grid-connected converter in the prior art;

[0097] Figure 2 A schematic flow chart showing a method for controlling inertia support of a grid-connected converter provided in an embodiment of the present application;

[0098] Figure 3 A structural schematic diagram of inertia control based on a frequency feedforward control strategy provided in an embodiment of the present application is shown;

[0099] Figure 4 A schematic diagram showing a performance comparison between a control method for an inertia support of a grid-connected converter provided in an embodiment of the present application and a control method for an inertia support of a grid-connected converter in the prior art;

[0100] Figure 5 Another structural schematic diagram of inertia control based on frequency feedforward control strategy provided in an embodiment of the present application is shown;

[0101] Figure 6 A structural schematic diagram of a control device for inertia support of a grid-connected converter provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0102] In order to enable those skilled in the art to better understand the technical solution of the present application, the present application is further described in detail below with reference to the accompanying drawings and embodiments.

[0103] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present application and are not configured to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by illustrating the examples of the present application.

[0104] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0105] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0106] In order to facilitate understanding of the control method for inertia support of a grid-connected converter provided in an embodiment of the present application, the main circuit topology and grid control system of the grid-connected converter in the prior art are first introduced below.

[0107] like Figure 1 As shown in the figure, the DC side is generally connected to a DC conversion circuit, a photovoltaic module or a battery system according to the application scenario. The main circuit topology of the grid-connected converter includes the DC side, a three-phase converter bridge, an LCL filter and a power grid. The DC voltage U dc After being connected to the LCL filter through a three-phase converter bridge, it is connected to the grid. Among them, the LCL filter includes a machine-side filter inductor L f , grid-side filter inductor L g And filter capacitor C f ; The power grid may include a power grid voltage V g and the equivalent impedance Z of the power grid g ; V pccIt can be the grid connection point voltage.

[0108] The grid-connected converter's grid-connected control system may include an active power synchronous control module 10, a reactive power control module 20, and a voltage and current control module 30. The active power synchronous control module 10 and the reactive power control module 20 are respectively connected to the voltage and current control module 30. Among them, the active power synchronous control module 10 may include an active frequency calculation submodule 11, a frequency setting submodule 12, and a phase integration submodule 13. After power calculation is performed using the current I and the voltage V at the output end of the three-phase converter bridge, the active power P and the reactive power Q are obtained. The active frequency of the active power P is calculated by the active frequency calculation submodule 11; then the given frequency consistent with the rated frequency of the system is determined by the frequency setting submodule 12; then the sum of the active frequency and the given frequency is integrated by the phase integration submodule 13 to obtain the phase angle θ; the reactive power Q and the reference reactive power P are integrated by the reactive power control module 20. ref Perform reactive power control and obtain the potential reference amplitude E ref Then the voltage and current control module 30 is used to control the phase angle θ and the potential reference amplitude E ref The pulse width modulation signal PWM is obtained by processing the current I and the voltage V at the output end of the three-phase converter bridge, and the pulse width modulation signal PWM is output to the three-phase converter bridge to control the on or off of the three-phase switch in the three-phase converter bridge.

[0109] It should be noted that in the prior art, the frequency determined by the frequency setting submodule 12 is a fixed value, which is generally the system rated frequency of 50 Hz or 60 Hz.

[0110] Example 1

[0111] Figure 2 A flow chart of a method for controlling inertia support of a grid-connected converter provided in an embodiment of the present application is shown.

[0112] The control method of the inertia support of the grid-connected converter provided in the embodiment of the present application can be executed by a grid-connected converter controller and a control device of the inertia support of the grid-connected converter, etc. The following takes the control method of the inertia support of the grid-connected converter executed by the grid-connected converter controller as an example for explanation.

[0113] like Figure 2 As shown, the control method of the inertia support of the grid-connected converter provided in the embodiment of the present application may include steps S210 to S230.

[0114] S210. Obtain a target real-time frequency value of the grid-connected converter, where the target real-time frequency value includes at least one of a real-time frequency value of the AC side voltage and a real-time frequency value of the grid-connected point voltage.

[0115] S220. Determine a frequency feedforward amount according to the target real-time frequency value.

[0116] S230. Determine a target phase angle according to the frequency feedforward amount. The target phase angle is used to adjust the output phase of the grid-connected converter so that the output phase is synchronized with the phase of the power grid.

[0117] According to the control method of the inertial support of the grid-connected converter provided in the embodiment of the present application, on the one hand, the frequency feedforward amount is determined by the target real-time frequency value, and then the target phase angle can be determined according to the frequency feedforward amount, so as to adjust the output phase of the grid-connected converter by the target phase angle, so that the output phase of the grid-connected converter is synchronized with the phase of the power grid, which can improve the stability of the operation of the power system; on the other hand, compared with the existing networking technology with only two control parameters, the embodiment of the present application adds the control parameter of the frequency feedforward amount to adjust the active power, and combines the existing damping coefficient and rotational inertia coefficient, or the droop coefficient and the first-order filter cutoff frequency, so as to independently design and implement the response speed, overshoot and inertia time constant, that is, it can simultaneously meet the three performance index requirements of the inertia support in terms of response speed, overshoot and inertia time constant.

[0118] The specific implementation of the above steps is described below.

[0119] In step S210 , the grid-connected converter may be an electrical device for converting electric power into a form suitable for use by a grid or a user.

[0120] For example, the grid-connected converter in the embodiment of the present application may include a grid-connected converter, wherein the grid-connected converter may be a device that provides a control converter to provide a constant AC electromotive force, thereby playing the role of a synchronous generator in stabilizing the power grid.

[0121] As an example, the target real-time frequency value may include a real-time frequency value of an AC side voltage.

[0122] As another example, the target real-time frequency value may include a real-time frequency value of a grid connection point voltage.

[0123] As yet another example, the target real-time frequency value may include a real-time frequency value of an AC side voltage and a real-time frequency value of a grid connection point voltage.

[0124] In some implementations, obtaining the target real-time frequency value may include:

[0125] Obtaining a target voltage, where the target voltage includes at least one of an AC side voltage and a grid connection point voltage, and the target voltage corresponds to a target real-time frequency value;

[0126] According to the target voltage, the target real-time frequency value is determined.

[0127] As an example, the target voltage may include an AC side voltage, and the target real-time frequency value may include a real-time frequency value of the AC side voltage.

[0128] As another example, the target voltage may include a grid connection point voltage, and the target real-time frequency value may include a real-time frequency value of the grid connection point voltage.

[0129] As another example, the target voltage may include the grid connection point voltage, then the target voltage may include the AC side voltage and the grid connection point voltage, and the target real-time frequency value may include the real-time frequency value of the AC side voltage and the real-time frequency value of the grid connection point voltage.

[0130] As an example, a voltage measuring device may be provided at the AC side and / or the grid connection point to obtain the AC side voltage and / or the grid connection point voltage.

[0131] As another example, the AC side voltage and / or the grid connection point voltage may be pre-stored in the grid-connected converter for subsequent direct call.

[0132] For example, the target real-time frequency value may be determined from the target voltage using Fourier transform or other spectrum analysis methods.

[0133] In some other implementations, obtaining the target real-time frequency value may include:

[0134] The target real-time frequency value is obtained from the frequency measuring device in real time.

[0135] It should be noted that the frequency measuring device is communicatively connected with the grid-connected current converter controller, and therefore, the grid-connected current converter controller can obtain the target real-time frequency value from the frequency measuring device in real time.

[0136] As an example, the target real-time frequency value may include a real-time frequency value of an AC side voltage, and the real-time frequency value of the AC side voltage may be acquired in real time from a frequency measuring device disposed on the AC side.

[0137] As another example, the target real-time frequency value may include the real-time frequency value of the grid connection point voltage, and the real-time frequency value of the AC side voltage may be acquired in real time from a frequency measurement device disposed at the grid connection point.

[0138] As another example, the target real-time frequency value may include the real-time frequency value of the AC side voltage and the real-time frequency value of the grid-connected point voltage. The real-time frequency value of the AC side voltage can be obtained in real time from a frequency measuring device set on the AC side, and the real-time frequency value of the AC side voltage can be obtained in real time from a frequency measuring device set at the grid-connected point.

[0139] In some further implementations, obtaining the target real-time frequency value may include:

[0140] The real-time frequency value of the AC side voltage and / or the grid connection point voltage in the upper level or the same line power system is used as the target real-time frequency value.

[0141] It should be noted that the frequency values ​​of each node in the superior or same line power system are the same, and therefore, when the AC power converter controller stores or obtains the real-time frequency value of the AC side voltage and / or the grid connection point voltage in the superior or same line power system, the real-time frequency value of the AC side voltage and / or the grid connection point voltage in the superior or same line power system can be used as the target real-time frequency value.

[0142] In step S220, after obtaining the target real-time frequency value of the grid-connected AC controller, the grid-connected AC controller may also determine a frequency feed-forward amount according to the target real-time frequency value.

[0143] In the embodiment of the present application, the frequency feedforward amount can be used as the output result of the frequency setting submodule and transmitted to the phase integration submodule, that is, the frequency feedforward amount can be output to the active synchronous control as the result of the frequency setting link.

[0144] In some implementations, determining the frequency feedforward amount according to the target real-time frequency value may include:

[0145] Determine the output signal type of the grid-connected converter according to the target real-time frequency value;

[0146] Determine the frequency feedforward amount based on the output signal type.

[0147] Exemplarily, the output signal types may include a reset signal and an enable signal.

[0148] In some examples, the output signal type includes a reset signal and an enable signal, and determining the output signal type of the grid-connected converter according to the target real-time frequency value includes:

[0149] When the target real-time frequency value satisfies the first preset condition, determining that the output signal type of the grid-connected converter is a reset signal;

[0150] When the target real-time frequency value satisfies the second preset condition, determining that the output signal type of the grid-connected converter is an enable signal;

[0151] Among them, the first preset condition includes ω1≤ω g ≤ω2、ω g >ω4 and ω g < any one of ω3; ω g Indicates the target real-time frequency value, ω1 indicates the lower limit of the frequency dead zone required by the inertia response, ω2 indicates the upper limit of the frequency dead zone required by the inertia response, ω3 indicates the lower limit of the frequency range of the inertia response, and ω4 indicates the upper limit of the frequency range of the inertia response;

[0152] The second preset condition includes ω3≤ω g <ω1 and ω4>ω g > any one of ω2.

[0153] As an example, the first preset condition includes ω1≤ω g ≤ω2.

[0154] As another example, the first preset condition includes ω g >ω4.

[0155] As yet another example, the first preset condition includes ω g <ω3.

[0156] As an example, the second preset condition includes ω3≤ω g <ω1.

[0157] As another example, the second preset condition includes ω4>ω g >ω2.

[0158] Exemplarily, the values ​​of ω1, ω2, ω3 and ω4 may be pre-stored in the grid-connected converter controller for subsequent direct calling.

[0159] In some implementations, the output signal type includes a reset signal and an enable signal, and determining the frequency feedforward amount according to the output signal type may include:

[0160] When the output signal type includes a reset signal, the target real-time frequency value is substituted into formula (1) to calculate and obtain the frequency feedforward value;

[0161] Formula (1) includes:

[0162] ω0=ω g (1)

[0163] Among them, ω0 represents the frequency feedforward; ω g Indicates the target real-time frequency value.

[0164] That is, when the output signal type includes a reset signal, the target real-time frequency value is used as the frequency feedforward amount.

[0165] Alternatively, when the output signal type includes an enable signal, the target real-time frequency value and the gain of the target filter are substituted into formula (2) for calculation to obtain the frequency feedforward value;

[0166] Formula (2) includes:

[0167] ω0=F(s)ω g (2)

[0168] Where F(s) represents the gain of the target filter.

[0169] That is, when the output signal type includes an enable signal, the product of the target real-time frequency value and the gain of the target filter is used as the frequency feedforward amount.

[0170] Exemplarily, the target filter may be a digital filter. The target filter may include a first-order filter, a second-order filter, and an N-order filter, where N is an integer greater than or equal to 3. Correspondingly, the gain of the target filter may include a first gain of a first-order filter, a second gain of a second-order filter, and a third gain of an N-order filter.

[0171] Exemplarily, formula (2) may include any one of formula (21), formula (22) and formula (23).

[0172] In some examples, the target filter comprises a first-order filter, and the gain of the target filter comprises a first gain of the first-order filter;

[0173] Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward value, the method further includes:

[0174] Acquire the operation factor and the first parameter corresponding to the first-order filter, the first parameter including the first active frequency modulation coefficient and the first inertia time constant;

[0175] Substitute the first active frequency modulation coefficient and the first inertia time constant into formula (3) to calculate and obtain the first cut-off frequency;

[0176] Formula (3) includes:

[0177]

[0178] Among them, ω J1 Represents the first cutoff frequency; K f1 Indicates the first active frequency modulation coefficient; T1 J represents the first inertia time constant;

[0179] Substitute the operation factor and the first cutoff frequency into formula (4) to calculate and obtain the first gain;

[0180] Formula (4) includes:

[0181]

[0182] Wherein, s represents the operation factor; F1(s) represents the first gain;

[0183] Formula (2) includes formula (21). Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation, the frequency feedforward amount is obtained, including:

[0184] Substitute the target real-time frequency value and the first gain into formula (21) to calculate and obtain the frequency feedforward value;

[0185] Among them, formula (21) includes:

[0186] ω0=F1(s)ω g (twenty one).

[0187] The operation factors may be complex frequency variables in Laplace transform.

[0188] The first active frequency modulation coefficient may be an active frequency modulation coefficient corresponding to a first-order filter.

[0189] The first inertia time constant may be an inertia time constant corresponding to a first-order filter.

[0190] The first cut-off frequency may be a cut-off frequency corresponding to a first-order filter.

[0191] The first gain may be a gain corresponding to a first-order filter. The characteristics of the first-order filter are determined by the required first inertia time constant.

[0192] Exemplarily, the grid-connected AC controller may pre-store the operation factor, the first active frequency modulation coefficient and the first inertia time constant for subsequent direct calling.

[0193] It should be noted that the first active frequency modulation coefficient K in the embodiment of the present application is f1 , and the second active frequency modulation coefficient K in the following f2 and the third active frequency modulation coefficient K f3 , which may be determined by standards or regulatory agency requirements.

[0194] In some other examples, the target filter comprises a second-order filter, and the gain of the target filter comprises a second gain of the second-order filter;

[0195] Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward value, the method further includes:

[0196] Obtaining the operation factor and the second parameter corresponding to the second-order filter, the second parameter including the second active frequency modulation coefficient, the system rated power, the damping ratio and the second inertia time constant;

[0197] Substituting the second active frequency modulation coefficient, the first system rated power, the first damping ratio and the second inertia time constant into formula (5) for calculation, the second cut-off frequency is obtained;

[0198] Formula (5) includes:

[0199]

[0200] Among them, ω J2 Represents the second cutoff frequency; K f2 Indicates the second active frequency modulation coefficient; T2 J represents the second inertia time constant; ξ represents the damping ratio; f f Indicates the system rated power;

[0201] Substitute the second cutoff frequency, the operation factor and the damping ratio into formula (6) to calculate and obtain the second gain;

[0202] Formula (6) includes:

[0203]

[0204] Wherein, s represents the operation factor; f2(s) represents the second gain;

[0205] Formula (2) includes formula (22). Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation, the frequency feedforward amount is obtained, including:

[0206] Substitute the target real-time frequency value and the second gain into formula (22) to calculate and obtain the frequency feedforward value;

[0207] Among them, formula (22) includes:

[0208] ω0=F2(s)ω g (twenty two).

[0209] The second active frequency modulation coefficient may be an active frequency modulation coefficient corresponding to a second-order filter.

[0210] The second inertia time constant may be an inertia time constant corresponding to a second-order filter.

[0211] The second cut-off frequency may be a cut-off frequency corresponding to a second-order filter.

[0212] The second gain may be a gain corresponding to a second-order filter. The characteristics of the second-order filter are determined by the required second inertia time constant.

[0213] It should be noted that the value range of ξ is generally greater than or equal to 0.5. The value of ξ is determined by the system inertia response characteristics, and the inertia response time decreases as ξ increases.

[0214] Exemplarily, the grid-connected AC controller may pre-store the operation factor, the second active frequency modulation coefficient, the system rated power, the damping ratio and the second inertia time constant for subsequent direct calling.

[0215] In some further examples, the target filter includes an N-th order filter, the gain of the target filter includes a third gain of the N-th order filter, and N is an integer greater than or equal to 3;

[0216] Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward value, the method further includes:

[0217] Decomposing the third inertia time constant of the N-order filter into m first inertia time constants and n second inertia time constants, the first inertia time constant is the inertia time constant corresponding to the first-order filter, the second inertia time constant is the inertia time constant corresponding to the second-order filter, and m and n are both integers;

[0218] Obtaining a first gain corresponding to each of the m first inertia time constants and a second gain corresponding to each of the n second inertia time constants;

[0219] Substituting all the first gains and all the second gains into formula (7) for calculation, a third gain is obtained;

[0220] Formula (7) includes:

[0221] F3(s)=F 11 (s)F 12 (s)…F 1m (s)F 21 (s)F 22 (s)…F 2n (s) (7)

[0222] Wherein, F3(s) represents the third gain; F 11 (s) represents the first gain corresponding to the first inertia time constant; F 12 (s) represents the first gain corresponding to the second first inertia time constant; F 1m (s) represents the first gain corresponding to the mth first inertia time constant; F 21 (s) represents the second gain corresponding to the second inertia time constant; F 22 (s) represents the second gain corresponding to the second inertia time constant; F 2m (s) represents the second gain corresponding to the mth second inertia time constant;

[0223] Formula (2) includes formula (23). Substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation, the frequency feedforward amount is obtained, including:

[0224] Substitute the target real-time frequency value and the third gain into formula (23) to calculate and obtain the frequency feedforward value;

[0225] Among them, formula (23) includes:

[0226] ω0=F3(s)ω g (twenty three).

[0227] The third inertia time constant may be an inertia time constant corresponding to an N-th order filter.

[0228] The third gain may be a gain corresponding to an N-th order filter.

[0229] The third inertia time constant R3 J Can meet:

[0230] Among them, T1 Ji represents the i-th first inertia time constant, T2 Jj represents the j-th second inertia time constant, 1≤i≤m, 1≤j≤n, and i and j are both integers.

[0231] Understandably, T1 Ji It can be realized by F1(s), T2 Jj It can be realized by F2(s). Then, the expression of F3(s) can satisfy: Among them, F 1i (s), i=1,2...m corresponds to F1(s), F 2j (s), i=1,2...n corresponds to F2(s).

[0232] Exemplarily, the grid-connected AC controller may pre-store the third inertia time constant of the N-th order filter for subsequent direct call.

[0233] It should be noted that, according to the control system operation performance and design objectives, the third inertia time constant of the N-order filter can be decomposed into m first inertia time constants and n second inertia time constants, and the decomposition is implemented as a feasible embodiment. The larger the sum of m and n, the more flexible the control characteristics that can be realized, and m can be equal to n or not equal to n, which is not limited here.

[0234] In step S230, after determining the frequency feedforward amount according to the target real-time frequency value, the grid-connected AC controller can also determine the target phase angle according to the frequency feedforward amount. The target phase angle is used to adjust the output phase of the grid-connected converter so that the output phase is synchronized with the phase of the power grid.

[0235] Exemplarily, the sum of the calculation results of the frequency feedforward amount and the active frequency may be integrated to obtain the target phase angle.

[0236] Figure 3 A schematic diagram of the structure of inertia control based on frequency feedforward control strategy provided by an embodiment of the present application is shown. Figure 3 As shown, frequency feedforward includes: first calculating the frequency to obtain the target real-time frequency value ω g , and then use the target real-time frequency value ω g Make a frequency range judgment, and then use the judgment result and the target real-time frequency value ω g , perform feedforward calculation and obtain the frequency feedforward value ω0. In other words, the inertial support control strategy based on frequency feedforward can include three parts: frequency acquisition, logical judgment and feedforward calculation.

[0237] Figure 4 The control method of the grid converter inertia support provided by the embodiment of the present application is compared with the control method of the grid converter inertia support in the prior art (i.e., traditional virtual synchronous machine control) when the active frequency modulation coefficient is 50. Figure 3 It can be seen that under the condition that the inertia time constant is 20s, when the frequency changes, the active power of the power system becomes unstable when the control method of the inertia support of the grid converter in the prior art is adopted. However, when the control method of the inertia support of the grid converter provided in the embodiment of the present application is adopted, the power system can still perform inertia response stably.

[0238] in, Figure 4 The horizontal axis is time t, and its unit is s; the vertical axis in the upper left corner is frequency f, and its unit is Hz; the vertical axis in the lower right corner is the active power p of the power system, and its unit is pu; the traditional VSG scheme is the traditional virtual synchronous machine control scheme, and the scheme of the present invention is the scheme of the embodiment of the present application.

[0239] It is understandable that the control method of the inertia support of the grid-connected converter provided in the embodiment of the present application, that is, the inertia support control strategy based on frequency feedforward, introduces a new control variable in active power control compared to the existing network control strategy, and corresponds to the inertia time constant, and its advantage is that a wider range of inertia capacity can be obtained. In addition, in the existing network control strategy, the inertia response control and the primary frequency modulation control are coupled due to the shared core control parameters. The control method of the inertia support of the grid-connected converter provided in the embodiment of the present application provides a new control variable for inertia control, and does not share the core control parameters with the primary frequency modulation, thereby completely decoupling from the primary frequency modulation design. In the steady-state process, the frequency feedforward control can be regarded as a direct pass; under the transient frequency change, the frequency feedforward control can increase the frequency control amount and adjust the active power. In combination with the damping coefficient and the moment of inertia coefficient or the droop coefficient and the cutoff frequency of the filter, the response speed, overshoot and inertia time constant can be independently designed and implemented.

[0240] The core of the control method for inertia support of the grid-connected converter provided in the embodiment of the present application is to generate a frequency difference in the frequency change process in the frequency setting link by designing a feedforward control strategy based on the frequency setting, thereby changing the active power of the grid-connected converter and realizing inertia support. Figure 5 The inertia control structure based on the frequency feedforward control strategy is shown.

[0241] Based on the realized inertia response in the traditional network control technology, the control method of the inertia support of the grid-connected converter provided in the embodiment of the present application is combined to increase the inertia support capacity. The inertia realization method of the traditional network control technology includes inertia simulation control in the active frequency control link or inertia simulation control in the active given control link, such as Figure 5 As shown. The design requirement of the inertia time constant of the grid-connected converter is T jt , T jt Can meet T Jt =T J1 +T J2 +T J3 Among them, T J1 Design the corresponding inertia time constant for active frequency control, which is realized by inertia simulation control in the active frequency control link; T J2 Design the corresponding inertia time constant for active given control, and implement it by inertia simulation control in active given control link; T J3 The corresponding inertia time constant is designed for frequency feedforward, which can be realized by frequency feedforward control strategy. J3 Any one of a first inertia time constant, a second inertia time constant, and a third inertia time constant may be included.

[0242] like Figure 5 As shown, the acquisition of frequency feedforward includes: first calculating the frequency to obtain the target real-time frequency value ω g , and then use the target real-time frequency value ω g Make a frequency range judgment, and then use the judgment result and the target real-time frequency value ω g , perform feedforward calculation and obtain the frequency feedforward value v0.

[0243] The active power given simulated inertia is calculated based on the frequency change rate RoCoF of the detection system and the proportional control coefficient k combined with the inertia demand J Calculate and get the active given simulated inertia P J Then the active given simulated inertia P J , Reference active power P ref The sum of the three, the actual active power P, is used as the input for inertia simulation control in the active frequency control link, that is, after calculation, the additional active power change instruction corresponding to the inertia demand is added to the active power instruction.

[0244] The active power simulation inertia is the traditional virtual synchronous machine control or inertia droop control. The virtual rotation inertia coefficient J, virtual damping coefficient D, or droop coefficient k and filter cutoff frequency ω are designed according to the inertia time constant. c , and obtain the active power simulated inertia.

[0245] The phase angle θ is obtained by integrating the sum of the frequency feedforward ω0 and the active power simulated inertia. The phase angle θ is used to adjust the output phase of the grid-connected converter to keep it synchronized with the phase of the power grid.

[0246] It is understandable that the embodiment of the present application can realize the wide range inertia support characteristics of the grid-connected converter by introducing a new frequency feedforward control strategy based on the traditional virtual synchronous machine control, inertia droop control, droop control and other network control. The embodiment of the present application can independently design the frequency feedforward control according to the inertia time constant, and independently design and realize the response speed, overshoot and inertia time constant in the inertia response by combining the damping coefficient and the rotational inertia coefficient or the droop coefficient and the filter cutoff frequency.

[0247] Based on the same inventive concept, an embodiment of the present application also provides a control device for inertia support of a grid-connected converter. The control device for inertia support of a grid-connected converter provided in an embodiment of the present application is described below in conjunction with the accompanying drawings.

[0248] Example 2

[0249] like Figure 6 As shown, the control device for inertia support of a grid-connected converter provided in an embodiment of the present application may include a first acquisition module 610 , a first determination module 620 and a second determination module 630 .

[0250] The first acquisition module 610 is used to acquire a target real-time frequency value of the grid-connected converter, wherein the target real-time frequency value includes at least one of a real-time frequency value of the AC side voltage and a real-time frequency value of the grid-connected point voltage;

[0251] A first determination module 620, connected to the first acquisition module 610, is used to determine a frequency feedforward amount according to a target real-time frequency value;

[0252] The second determination module 630 is connected to the first determination module 620 and is used to determine a target phase angle according to the frequency feedforward amount. The target phase angle is used to adjust the output phase of the grid-connected converter so that the output phase is synchronized with the phase of the power grid.

[0253] According to the control device of the inertial support of the grid-connected converter provided in the embodiment of the present application, on the one hand, the frequency feedforward amount is determined by the target real-time frequency value, and then the target phase angle can be determined according to the frequency feedforward amount, so as to adjust the output phase of the grid-connected converter by the target phase angle, so that the output phase of the grid-connected converter is synchronized with the phase of the power grid, which can improve the stability of the operation of the power system; on the other hand, compared with the existing networking technology with only two control parameters, the embodiment of the present application adds the control parameter of the frequency feedforward amount to adjust the active power, and combines the existing damping coefficient and rotational inertia coefficient, or the droop coefficient and the first-order filter cutoff frequency, so as to independently design and realize the response speed, overshoot and inertia time constant, that is, it can simultaneously meet the three performance index requirements of the inertia support in terms of response speed, overshoot and inertia time constant.

[0254] In some implementations, the first determining module 620 includes:

[0255] A first determination submodule, used to determine the output signal type of the grid-connected converter according to the target real-time frequency value;

[0256] The second determining submodule is connected to the first determining submodule and is used to determine the frequency feedforward amount according to the output signal type.

[0257] In some implementations, the output signal type includes a reset signal and an enable signal, and the first determination submodule includes:

[0258] A first determining unit, configured to determine that the output signal type of the grid-connected converter is a reset signal when the target real-time frequency value satisfies a first preset condition;

[0259] A second determining unit, configured to determine that the output signal type of the grid-connected converter is an enabling signal when the target real-time frequency value satisfies a second preset condition;

[0260] Among them, the first preset condition includes ω1≤ω g ≤ω2、ω g >ω4 and ω g < any one of ω3; ω g Indicates the target real-time frequency value, ω1 indicates the lower limit of the frequency dead zone required by the inertia response, ω2 indicates the upper limit of the frequency dead zone required by the inertia response, ω3 indicates the lower limit of the frequency range of the inertia response, and ω4 indicates the upper limit of the frequency range of the inertia response;

[0261] The second preset condition includes ω3≤ω g <ω1 and ω4>ω g > any one of ω2.

[0262] In some implementations, the output signal type includes a reset signal and an enable signal, and the second determination submodule includes:

[0263] A first calculation unit is used for substituting the target real-time frequency value into formula (1) for calculation to obtain a frequency feedforward value when the output signal type includes a reset signal;

[0264] Formula (1) includes:

[0265] ω0=ω g (1)

[0266] Among them, ω0 represents the frequency feedforward; ω g Indicates the target real-time frequency value;

[0267] Alternatively, the second calculation unit is used to substitute the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward amount when the output signal type includes an enable signal;

[0268] Formula (2) includes:

[0269] ω0=F(s)ω g (2)

[0270] Where F(s) represents the gain of the target filter.

[0271] In some embodiments, the target filter comprises a first-order filter, and the gain of the target filter comprises a first gain of the first-order filter;

[0272] The device may also include:

[0273] A second acquisition module, used for acquiring the operation factor and the first parameter corresponding to the first-order filter, the first parameter including the first active frequency modulation coefficient and the first inertia time constant;

[0274] A first calculation module, used for substituting the first active frequency modulation coefficient and the first inertia time constant into formula (3) to calculate and obtain a first cut-off frequency;

[0275] Formula (3) includes:

[0276]

[0277] Among them, ω J1 Represents the first cutoff frequency; K f0 Indicates the first active frequency modulation coefficient; T1 J represents the first inertia time constant;

[0278] A second calculation module is used to substitute the operation factor and the first cutoff frequency into formula (4) to calculate and obtain a first gain;

[0279] Formula (4) includes:

[0280]

[0281] Wherein, s represents the operation factor; F1(s) represents the first gain;

[0282] Formula (2) includes formula (21), and the second calculation unit can be specifically used for:

[0283] Substitute the target real-time frequency value and the first gain into formula (21) to calculate and obtain the frequency feedforward value;

[0284] Among them, formula (21) includes:

[0285] ω0=F1(s)ω f (twenty one).

[0286] In some embodiments, the target filter comprises a second-order filter, and the gain of the target filter comprises a second gain of the second-order filter;

[0287] The device may also include:

[0288] A third acquisition module is used to acquire the operation factor and the second parameter corresponding to the second-order filter, the second parameter including the second active frequency modulation coefficient, the system rated power, the damping ratio and the second inertia time constant;

[0289] A third calculation module is used to substitute the second active frequency modulation coefficient, the first system rated power, the first damping ratio and the second inertia time constant into formula (5) to calculate and obtain a second cut-off frequency;

[0290] Formula (5) includes:

[0291]

[0292] Among them, ω J2 Represents the second cutoff frequency; K f2 Indicates the second active frequency modulation coefficient; T2 J represents the second inertia time constant; ξ represents the damping ratio; f g Indicates the system rated power;

[0293] A fourth calculation module, used for substituting the second cutoff frequency, the operation factor and the damping ratio into formula (6) to calculate and obtain a second gain;

[0294] Formula (6) includes:

[0295]

[0296] Wherein, s represents the operation factor; F2(s) represents the second gain;

[0297] Formula (2) includes formula (22), and the second calculation unit can be specifically used for:

[0298] Substitute the target real-time frequency value and the second gain into formula (22) to calculate and obtain the frequency feedforward value;

[0299] Among them, formula (22) includes:

[0300] ω0=F2(s)ω g (twenty two).

[0301] In some embodiments, the target filter includes an N-order filter, the gain of the target filter includes a third gain of the N-order filter, and N is an integer greater than or equal to 3;

[0302] The device may also include:

[0303] A decomposition module, used for decomposing the third inertia time constant of the N-order filter into m first inertia time constants and n second inertia time constants, the first inertia time constant is the inertia time constant corresponding to the first-order filter, the second inertia time constant is the inertia time constant corresponding to the second-order filter, and m and n are both integers;

[0304] a fourth acquisition module, configured to acquire a first gain corresponding to each of the m first inertia time constants and a second gain corresponding to each of the n second inertia time constants;

[0305] a fifth calculation module, used for substituting all the first gains and all the second gains into formula (7) to calculate and obtain a third gain;

[0306] Formula (7) includes:

[0307] F3(s)=F 11 (s)F 12 (s)…F 1m (s)F 21 (s)F 22 (s)…F 2n (s) (7)

[0308] Wherein, F3(s) represents the third gain; F 11 (s) represents the first gain corresponding to the first inertia time constant; F 12 (s) represents the first gain corresponding to the second first inertia time constant; F 1m (s) represents the first gain corresponding to the mth first inertia time constant; F 21 (s) represents the second gain corresponding to the second inertia time constant; F 22(s) represents the second gain corresponding to the second inertia time constant; F 2m (s) represents the second gain corresponding to the mth second inertia time constant;

[0309] Formula (2) includes formula (23), and the second calculation unit can be specifically used for:

[0310] Substitute the target real-time frequency value and the third gain into formula (23) to calculate and obtain the frequency feedforward value;

[0311] Among them, formula (23) includes:

[0312] ω0=F3(s)ω g (twenty three).

[0313] In some implementations, the first acquisition module 610 may be specifically configured to:

[0314] Obtaining a target voltage, where the target voltage includes at least one of an AC side voltage and a grid connection point voltage, and the target voltage corresponds to a target real-time frequency value;

[0315] According to the target voltage, determine the target real-time frequency value;

[0316] Alternatively, the target real-time frequency value is obtained in real time from a frequency measuring device;

[0317] Alternatively, the real-time frequency value of the AC side voltage and / or the grid connection point voltage in the upper level or the same line power system is used as the target real-time frequency value.

[0318] The control device for the inertia support of the grid-connected converter provided in the embodiment of the present application can be used to execute the control method for the inertia support of the grid-connected converter, that is, it has the beneficial effects and implementation methods of the control method for the inertia support of the grid-connected converter provided by the control of the inertia support of the grid-connected converter in the embodiment of the present application. For details, please refer to the specific description of the control of the inertia support of the grid-connected converter in the above-mentioned embodiment 1, which will not be repeated in this embodiment.

[0319] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present application, but the present application is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of the present application, and these modifications and improvements are also considered to be within the scope of protection of the present application.

Claims

1. A control method for inertia support of a grid-connected converter, characterized in that: include: Acquire a target real-time frequency value of the grid-connected converter, wherein the target real-time frequency value includes at least one of a real-time frequency value of the AC side voltage and a real-time frequency value of the grid-connected point voltage; Determining a frequency feedforward amount according to the target real-time frequency value; A target phase angle is determined according to the frequency feedforward amount, and the target phase angle is used to adjust the output phase of the grid-connected converter so that the output phase is synchronized with the phase of the power grid.

2. The method according to claim 1, characterized in that Determining the frequency feedforward amount according to the target real-time frequency value includes: Determining an output signal type of a grid-connected converter according to the target real-time frequency value; The frequency feedforward amount is determined according to the output signal type.

3. The method according to claim 2, characterized in that The output signal type includes a reset signal and an enable signal, and the determining the output signal type of the grid-connected converter according to the target real-time frequency value includes: When the target real-time frequency value satisfies the first preset condition, determining that the output signal type of the grid-connected converter is the reset signal; When the target real-time frequency value satisfies a second preset condition, determining that the output signal type of the grid-connected converter is the enable signal; Among them, the first preset condition includes ω1≤ω g ≤ω2、ω g >ω4 and ω g < any one of ω3; ω g Indicates the target real-time frequency value, ω1 indicates the lower limit of the frequency dead zone required by the inertia response, ω2 indicates the upper limit of the frequency dead zone required by the inertia response, ω3 indicates the lower limit of the frequency range of the inertia response, and ω4 indicates the upper limit of the frequency range of the inertia response; The second preset condition includes ω3≤ω g <ω1 and ω4>ω g >any one of ω2.

4. The method according to claim 2, characterized in that: The output signal type includes a reset signal and an enable signal, and determining the frequency feedforward amount according to the output signal type includes: In the case where the output signal type includes the reset signal, the target real-time frequency value is substituted into formula (1) for calculation to obtain a frequency feedforward value; The formula (1) includes: ω0=ω g (1) Among them, ω0 represents the frequency feedforward; ω g Indicates the target real-time frequency value; Alternatively, when the output signal type includes the enable signal, the target real-time frequency value and the gain of the target filter are substituted into formula (2) for calculation to obtain a frequency feedforward value; The formula (2) includes: ω0=F(s)ω g (2) Where F(s) represents the gain of the target filter.

5. The method according to claim 4, characterized in that The target filter comprises a first-order filter, and the gain of the target filter comprises a first gain of the first-order filter; Before substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward value, the method further includes: Acquire an operation factor and a first parameter corresponding to the first-order filter, wherein the first parameter includes a first active frequency modulation coefficient and a first inertia time constant; Substituting the first active frequency modulation coefficient and the first inertia time constant into formula (3) for calculation, a first cut-off frequency is obtained; The formula (3) includes: Among them, ω J1 Represents the first cutoff frequency; K f1 Indicates the first active frequency modulation coefficient; T1 J represents the first inertia time constant; Substituting the operation factor and the first cutoff frequency into formula (4) to calculate, a first gain is obtained; The formula (4) includes: Wherein, s represents the operation factor; F1(s) represents the first gain; The formula (2) includes the formula (21), and the target real-time frequency value and the gain of the target filter are substituted into the formula (2) for calculation to obtain the frequency feedforward value, including: Substituting the target real-time frequency value and the first gain into formula (21) for calculation, the frequency feedforward value is obtained; Wherein, the formula (21) includes: ω0=F1(s)ω g (21).

6. The method according to claim 4, characterized in that The target filter comprises a second-order filter, and the gain of the target filter comprises a second gain of the second-order filter; Before substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward value, the method further includes: Acquire an operation factor and a second parameter corresponding to the second-order filter, wherein the second parameter includes a second active frequency modulation coefficient, a system rated power, a damping ratio, and a second inertia time constant; Substituting the second active frequency modulation coefficient, the first system rated power, the first damping ratio and the second inertia time constant into formula (5) for calculation, a second cut-off frequency is obtained; The formula (5) includes: Among them, ω J2 Represents the second cutoff frequency; K f2 Indicates the second active frequency modulation coefficient; T2 J represents the second inertia time constant; ξ represents the damping ratio; f g Indicates the system rated power; Substituting the second cutoff frequency, the operation factor and the damping ratio into formula (6) for calculation, a second gain is obtained; The formula (6) includes: Wherein, s represents the operation factor; F2(s) represents the second gain; The formula (2) includes the formula (22), and the target real-time frequency value and the gain of the target filter are substituted into the formula (2) for calculation to obtain the frequency feedforward value, including: Substituting the target real-time frequency value and the second gain into formula (22) for calculation, the frequency feedforward value is obtained; Wherein, the formula (22) includes: η0=F2(s)ω g (22)。 7. The method according to claim 4, characterized in that The target filter includes an N-order filter, the gain of the target filter includes a third gain of the N-order filter, and N is an integer greater than or equal to 3; Before substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain the frequency feedforward value, the method further includes: Decomposing the third inertia time constant of the N-order filter into m first inertia time constants and n second inertia time constants, wherein the first inertia time constant is the inertia time constant corresponding to the first-order filter, the second inertia time constant is the inertia time constant corresponding to the second-order filter, and m and n are both integers; Obtaining a first gain corresponding to each of the m first inertia time constants and a second gain corresponding to each of the n second inertia time constants; Substituting all the first gains and all the second gains into formula (7) for calculation, a third gain is obtained; The formula (7) includes: F3(s)=F 11 (s)F 12 (s)…F 1m (s)F 21 (s)F 22 (s)…F 2n (s)(7) Wherein, F3(s) represents the third gain; F 11 (s) represents the first gain corresponding to the first inertia time constant; F 12 (s) represents the first gain corresponding to the second first inertia time constant; F 1m (s) represents the first gain corresponding to the mth first inertia time constant; F 21 (s) represents the second gain corresponding to the second inertia time constant; F 22 (s) represents the second gain corresponding to the second inertia time constant; F 2m (s) represents the second gain corresponding to the mth second inertia time constant; The formula (2) includes the formula (23), wherein the target real-time frequency value and the gain of the target filter are substituted into the formula (2) for calculation to obtain the frequency feedforward value, including: Substituting the target real-time frequency value and the third gain into formula (23) for calculation, a frequency feedforward value is obtained; Wherein, the formula (23) includes: ω0=F3(s)ω g (23).

8. The method according to any one of claims 1 to 7, characterized in that The step of obtaining the target real-time frequency value includes: Obtaining a target voltage, the target voltage including at least one of an AC side voltage and a grid connection point voltage, and the target voltage corresponds to the target real-time frequency value; Determining a target real-time frequency value according to the target voltage; Alternatively, the target real-time frequency value is obtained in real time from a frequency measuring device; Alternatively, the real-time frequency value of the AC side voltage and / or the grid connection point voltage in the upper level or the same line power system is used as the target real-time frequency value.

9. A control device for inertia support of a grid-connected converter, characterized in that: include: A first acquisition module is used to acquire a target real-time frequency value of the grid-connected converter, wherein the target real-time frequency value includes at least one of a real-time frequency value of an AC side voltage and a real-time frequency value of a grid-connected point voltage; A first determining module, connected to the first acquiring module, for determining a frequency feedforward amount according to the target real-time frequency value; The second determination module is connected to the first determination module and is used to determine a target phase angle according to the frequency feedforward amount, and the target phase angle is used to adjust the output phase of the grid-connected converter so that the output phase is synchronized with the phase of the power grid.

10. The device according to claim 9, characterized in that The first determining module includes: A first determination submodule, configured to determine an output signal type of the grid-connected converter according to the target real-time frequency value; The second determining submodule is connected to the first determining submodule, and is used to determine the frequency feedforward amount according to the output signal type.

11. The device according to claim 10, characterized in that The output signal type includes a reset signal and an enable signal, and the first determination submodule includes: A first determining unit, configured to determine that the output signal type of the grid-connected converter is the reset signal when the target real-time frequency value satisfies a first preset condition; A second determining unit, configured to determine that the output signal type of the grid-connected converter is the enabling signal when the target real-time frequency value satisfies a second preset condition; Among them, the first preset condition includes ω1≤ω g ≤ω2、ω g >ω4 and ω g < any one of ω3; ω g Indicates the target real-time frequency value, ω1 indicates the lower limit of the frequency dead zone required by the inertia response, ω2 indicates the upper limit of the frequency dead zone required by the inertia response, ω3 indicates the lower limit of the frequency range of the inertia response, and ω4 indicates the upper limit of the frequency range of the inertia response; The second preset condition includes ω3≤ω g <ω1 and ω4>ω g >any one of ω2.

12. The device according to claim 10, characterized in that The output signal type includes a reset signal and an enable signal, and the second determination submodule includes: A first calculation unit is used for substituting the target real-time frequency value into formula (1) to calculate and obtain a frequency feedforward value when the output signal type includes the reset signal; The formula (1) includes: ω0=ω g (1) Among them, ω0 represents the frequency feedforward; ω g Indicates the target real-time frequency value; Alternatively, a second calculation unit is used for, when the output signal type includes the enable signal, substituting the target real-time frequency value and the gain of the target filter into formula (2) for calculation to obtain a frequency feedforward amount; The formula (2) includes: ω0=F(s)ω g (2) Where F(s) represents the gain of the target filter.

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