High-proportion new energy power grid frequency rotational inertia control method and system

Abstract

The invention discloses a high-proportion new energy power grid frequency rotational inertia control method and system. The method comprises the following steps: establishing a virtual rotor motion equation controlled by a new energy grid-connected converter VSG; obtaining an active-frequency droop equation; deriving a mathematical model of the output voltage of the new energy grid-connected converter VSG control system under a dq two-phase coordinate system; calculating the output power of the VSG when the new energy grid-connected converter VSG control system stably operates; an energy composition function is adopted to analyze a transient energy change process when the frequency of the new energy grid-connected converter VSG is adjusted; a novel self-adaptive virtual inertia is obtained; a high-proportion new energy power grid frequency rotational inertia control equation used for reducing the oscillation frequency during frequency adjustment of the new energy grid-connected converter VSG is obtained, and adjustment of the new energy power grid frequency is achieved. According to the invention, a novel VSG control strategy is adopted, the VSG control strategy is improved, the frequency change rate is introduced to represent the virtual inertia, and the adjustment deviation and the adjustment time during the frequency adjustment of the new energy grid-connected converter VSG are reduced.

Description

Technical Field

[0001] The present invention belongs to the field of new energy technology, and in particular relates to a frequency rotation inertia control method and system for a high-proportion new energy power grid. Background Art

[0002] With the rapid development of new energy and the advancement of clean energy substitution, conventional synchronous generators in the power system have been replaced by new energy in large quantities. The output of new energy in the power grid continues to increase, and the proportion of conventional units continues to decrease, causing the effective rotational inertia of the power system to continue to decrease, resulting in an increase in the risk of system frequency stability. When the system fails or there is a large power loss, the insufficient system inertia can easily cause frequency stability problems in the entire network. Large-scale new energy access that does not have the ability to actively support inertia and frequency will bring huge challenges to the safe and stable operation of the power system.

[0003] When there is power imbalance in the interconnection lines connected to the high-proportion renewable energy grid, the VSG control system of the renewable energy grid-connected converter responds to power changes in real time through virtual inertia and virtual damping links, dynamically compensates for unbalanced power, and achieves the purpose of suppressing frequency fluctuations. In traditional VSG control, virtual inertia and virtual damping are fixed values. When large power fluctuations and frequency oscillations occur, it is impossible to adjust the VSG virtual parameters in real time to suppress transient shocks. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for controlling the frequency rotation inertia of a high-proportion renewable energy power grid, adopt a new VSG control strategy, and improve the VSG control strategy, introduce the frequency change rate to characterize the virtual inertia, and reduce the adjustment deviation and adjustment time during the VSG frequency adjustment of the renewable energy grid-connected converter.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for controlling frequency moment of inertia of a high-proportion renewable energy power grid, comprising the following steps:

[0007] 1) Establish the virtual rotor motion equation of the VSG control of the new energy grid-connected converter;

[0008] 2) performing frequency droop control on the active power in the virtual rotor motion equation obtained in step 1) to obtain an active power-frequency droop equation;

[0009] 3) Using Kirchhoff's voltage law and considering the coupled components of the dq axis current, the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system is derived;

[0010] 4) Based on the mathematical model obtained in step 3), calculate the output power of the VSG when the VSG control system of the new energy grid-connected converter is in stable operation;

[0011] 5) Using the output power obtained in step 4) and the virtual rotor motion equation in step 1), the energy composition function is used to analyze the transient energy change process of the new energy grid-connected converter VSG during frequency adjustment;

[0012] 6) According to the relationship between the current angular frequency and the initial angular frequency, combined with the energy composition function analysis in step 5), and the frequency adjustment change rate of the new energy grid-connected converter VSG in the acceleration and deceleration stages of the virtual angular frequency, the frequency change rate is introduced to characterize the virtual inertia, and finally a new adaptive virtual inertia is obtained;

[0013] 7) The new adaptive virtual inertia obtained in step 6) is introduced into the virtual rotor motion equation of step 1) to obtain a high-proportion new energy grid frequency rotation inertia control equation for reducing the oscillation frequency during frequency adjustment of the new energy grid-connected converter VSG, thereby realizing the adjustment of the new energy grid frequency.

[0014] A further improvement of the present invention is that step 1) establishes a virtual rotor motion equation controlled by a new energy grid-connected converter VSG, comprising: Where: H is the VSG virtual inertia; D is the VSG virtual damping; ω0 is the synchronous angular velocity of the grid-connected converter of the new energy grid; P m Output virtual mechanical power for VSG; P e is the actual output value of active and reactive power of the new energy grid-connected converter system; δ and ω are the virtual power angle and virtual electrical angular velocity of VSG, respectively.

[0015] A further improvement of the present invention is that the specific implementation method of step 2) is: the active power in the virtual rotor motion equation obtained in step 1) is subjected to frequency droop control to obtain the active power-frequency droop equation: P m =P ref +m(ω-ω0); where: m is the active power-frequency droop coefficient; P ref is the active power target value.

[0016] A further improvement of the present invention is that the specific implementation method of step 3) is: using Kirchhoff's voltage law and considering the coupling component of the dq axis current, deriving a mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system, including: Where: L is the equivalent inductance of the new energy grid-connected converter; u abc is the three-phase voltage at the grid connection point, i.e., the grid-side voltage; e abc 、i abcis the AC three-phase output voltage and current of the new energy grid-connected converter VSG; R is the equivalent resistance of the new energy grid-connected converter; define T abc→dq0 The Park transformation matrix is ​​introduced, and the dq axis current coupling component is introduced to obtain the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system: In the dq two-phase coordinate system, the output voltage and grid-connected voltage of the new energy grid-connected converter VSG exist:

[0017] A further improvement of the present invention is that the specific implementation method of step 4) is: based on the mathematical model obtained in step 3), the output power of the VSG when the VSG control system of the new energy grid-connected converter is in stable operation is calculated:

[0018] A further improvement of the present invention is that the specific implementation method of step 5) is: using the output power obtained in step 4) and the virtual rotor motion equation in step 1), an energy composition function is used to analyze the transient energy change process of the new energy grid-connected converter VSG during frequency adjustment: Where: W d , W s , W d is the energy required for kinetic energy, potential energy and damping of the new energy grid-connected converter VSG; δ0 is the initial virtual power angle of the new energy grid-connected converter VSG; P δ P is the output power of the new energy grid-connected converter VSG when the virtual power angle is δ; δ0 When the virtual power angle is the initial power angle, the new energy grid-connected converter VSG output power.

[0019] A further improvement of the present invention is that the specific implementation method of step 6) is: according to the relationship between the current angular frequency and the initial angular frequency, combined with the energy composition function analysis of step 5), and the frequency adjustment change rate of the new energy grid-connected converter VSG in the acceleration and deceleration stages of the virtual angular frequency, when the frequency of the new energy grid-connected converter VSG is adjusted, according to the relationship between ω and ω0, it is divided into: ω>ω0 stage and ω<ω0 stage; ω>ω0 stage includes stage a and stage b, wherein: stage a dω / dt>0, stage b dω / dt<0; ω<ω0 stage includes stage c and stage d, wherein: stage c dω / dt<0; stage d ω / dt>0; in stage a, W d Gradually increasing, W s Gradually decreases, and enters stage b under the action of kinetic energy, W d Gradually decrease, W s Gradually increases, and reciprocates under the action of potential energy; considering the VSG damping effect energy W d , new energy grid-connected converter VSG frequency regulation total energy W zDuring the oscillation process, 2 gradually decreases, and the frequency regulation of the new energy grid-connected converter VSG tends to be stable until the frequency is stable; it is proposed to increase the virtual moment of inertia H in the a stage and the d stage, that is, the virtual angular frequency acceleration stage to constrain the increase of the virtual angular frequency and reduce the virtual angular frequency regulation deviation, and at the same time, increase the virtual damping coefficient D to reduce the virtual angular frequency overshoot, and suppress the frequency oscillation instability caused by the excessive virtual moment of inertia H; in the b stage and the c stage, that is, the virtual angular frequency deceleration stage, reduce the virtual moment of inertia H to quickly restore the frequency to a stable value, and at the same time, reduce the virtual damping coefficient D to reduce the dynamic adjustment time of the new energy grid-connected converter VSG control system, so that the frequency regulation of the new energy grid-connected converter VSG tends to be stable faster; introduce the frequency change rate to characterize the virtual inertia, and obtain a new adaptive virtual inertia: Where: H0 is the initial value of the virtual inertia of the new energy grid-connected converter VSG, corresponding to the rated virtual inertia when not participating in frequency regulation; k i is the virtual inertia adjustment coefficient; when the new virtual inertia H i Adaptive adjustment, virtual damping D i According to H i Automatic adjustment, H i and D i Joint coordinated control can reduce the oscillation frequency during VSG frequency adjustment of the new energy grid-connected converter and maintain the stability of VSG frequency regulation.

[0020] A further improvement of the present invention is that the specific implementation method of step 7) is: introducing the new adaptive virtual inertia obtained in step 6) into the virtual rotor motion equation of step 1) to obtain a high-proportion new energy grid frequency rotation inertia control equation for reducing the oscillation frequency during frequency adjustment of the new energy grid-connected converter VSG:

[0021] A frequency rotation inertia control system for a high-proportion renewable energy grid, comprising:

[0022] The first equation building module builds the virtual rotor motion equation for VSG control of the new energy grid-connected converter;

[0023] The second equation building module performs frequency droop control on the active power in the virtual rotor motion equation obtained in the first equation building module to obtain an active power-frequency droop equation;

[0024] The mathematical model derivation module uses Kirchhoff's voltage law and considers the coupling components of the dq axis current to derive the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system;

[0025] The calculation module calculates the output power of the VSG when the VSG control system of the new energy grid-connected converter is in stable operation based on the mathematical model obtained by the mathematical model derivation module;

[0026] The third equation building module uses the output power obtained by the calculation module and the virtual rotor motion equation of the first equation building module, and adopts the energy composition function to analyze the transient energy change process of the new energy grid-connected converter VSG during frequency adjustment;

[0027] The analysis and processing module, based on the relationship between the current angular frequency and the initial angular frequency, combines the third equation to establish the energy composition function analysis of the module, as well as the frequency adjustment change rate of the new energy grid-connected converter VSG in the acceleration and deceleration stages of the virtual angular frequency, and introduces the frequency change rate to characterize the virtual inertia, and finally obtains a new adaptive virtual inertia;

[0028] The adjustment module introduces the new adaptive virtual inertia obtained by the analysis and processing module into the virtual rotor motion equation of the first equation establishment module, and obtains the high-proportion new energy grid frequency rotation inertia control equation for reducing the oscillation frequency during the frequency adjustment of the new energy grid-connected converter VSG, thereby realizing the adjustment of the new energy grid frequency.

[0029] A further improvement of the present invention is that in the first equation building module, a virtual rotor motion equation for the control of the new energy grid-connected converter VSG is established, including: Where: H is the VSG virtual inertia; D is the VSG virtual damping; ω0 is the synchronous angular velocity of the grid-connected converter of the new energy grid; P m Output virtual mechanical power for VSG; P e is the actual output value of active and reactive power of the new energy grid-connected converter system; δ and ω are the virtual power angle and virtual electrical angular velocity of VSG, respectively.

[0030] Compared with the prior art, the present invention has at least the following beneficial technical effects, all of which are derived from the innovative technical means proposed by the present invention and its significant advantages in practical applications:

[0031] The present invention proposes a frequency rotation inertia control method and system for a high-proportion renewable energy power grid, and innovatively adopts a VSG (Virtual Synchronous Generator) control strategy in the renewable energy grid-connected converter. This strategy endows the renewable energy power generation system with virtual inertia, damping and virtual excitation regulation characteristics by simulating the dynamic behavior of traditional synchronous generators. Since the VSG control strategy can simulate the rotor motion equation of the synchronous generator, the renewable energy power generation system exhibits similar response characteristics to traditional generators in the power grid, thereby effectively improving the stability and controllability of the renewable energy power grid. This innovative control strategy solves the problem of large frequency fluctuations and poor stability caused by the lack of inertial support in the renewable energy power generation system, thereby achieving stable regulation and efficient operation of the frequency of the renewable energy power grid.

[0032] The present invention has made significant improvements to the traditional VSG control strategy and creatively proposed a new adaptive virtual inertia VSG control method. The core of this method is to introduce the frequency change rate to characterize the virtual inertia, and dynamically adjust the virtual inertia parameters of the VSG by real-time monitoring and analyzing the frequency changes. This adaptive adjustment mechanism can more accurately reflect the actual operating status of the power grid, and effectively reduce the adjustment deviation and adjustment time of the new energy grid-connected converter VSG during the frequency adjustment process. Compared with the traditional fixed virtual inertia control method, the new adaptive virtual inertia VSG control method of the present invention has higher flexibility and adaptability, and can respond to changes in the power grid frequency more quickly, thereby further improving the frequency stability and response speed of the new energy power grid. This innovative technical means not only solves the problems of adjustment accuracy and response speed existing in the traditional VSG control strategy during the frequency adjustment process, but also provides strong technical support for the intelligent and refined management of the new energy power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 The grid-connected structure and control topology diagram of the new energy grid-connected converter VSG;

[0035] Figure 2 The VSG grid-connected equivalent circuit diagram is used for the new energy grid-connected converter;

[0036] Figure 3 The curve diagram of power angle and angular frequency variation of VSG used in the grid-connected converter of new energy;

[0037] Figure 4 This is a structural block diagram of a frequency rotation inertia control system for a high-proportion new energy power grid according to the present invention. DETAILED DESCRIPTION

[0038] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0039] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0040] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0041] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0042] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0043] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0044] Example 1

[0045] The present invention provides a method for controlling the frequency moment of inertia of a high-proportion new energy power grid, comprising the following steps:

[0046] 1) Establish the virtual rotor motion equation of the VSG control of the new energy grid-connected converter;

[0047] 2) performing frequency droop control on the active power in the virtual rotor motion equation obtained in step 1) to obtain an active power-frequency droop equation;

[0048] 3) Using Kirchhoff's voltage law and considering the coupled components of the dq axis current, the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system is derived;

[0049] 4) Based on the mathematical model obtained in step 3), calculate the output power of the VSG when the VSG control system of the new energy grid-connected converter is in stable operation;

[0050] 5) Using the output power obtained in step 4) and the virtual rotor motion equation in step 1), the energy composition function is used to analyze the transient energy change process of the new energy grid-connected converter VSG during frequency adjustment;

[0051] 6) According to the relationship between the current angular frequency and the initial angular frequency, combined with the energy composition function analysis in step 5), and the frequency adjustment change rate of the new energy grid-connected converter VSG in the acceleration and deceleration stages of the virtual angular frequency, the frequency change rate is introduced to characterize the virtual inertia, and finally a new adaptive virtual inertia is obtained;

[0052] 7) The new adaptive virtual inertia obtained in step 6) is introduced into the virtual rotor motion equation of step 1) to obtain a high-proportion new energy grid frequency rotation inertia control equation for reducing the oscillation frequency during frequency adjustment of the new energy grid-connected converter VSG, thereby realizing the adjustment of the new energy grid frequency.

[0053] Example 2

[0054] like Figure 1 As shown, C dc It is the DC side filter capacitor of the new energy grid-connected converter; R f , L f , C f Constitute the LCL filter circuit; abc 、i abc is the AC three-phase output voltage and current of the new energy grid-connected converter VSG; u abc is the three-phase voltage at the grid connection point, i.e., the grid side voltage; L g , R g The line impedance is formed; P e , Q e are respectively the actual output values ​​of active and reactive power of the new energy grid-connected converter system. In the VSG control model: ref , Q ref are active power and reactive power target values ​​respectively; P m is the virtual mechanical power output by VSG; δ and ω are the virtual power angle and virtual electrical angular velocity of VSG respectively; E is the three-phase voltage output by the new energy grid-connected converter VSG e abc Amplitude; U is the grid connection point voltage U abc Amplitude; U ref It is the reference voltage of the grid connection point.

[0055] The virtual rotor motion equation of the VSG control of the new energy grid-connected converter can be expressed as:

[0056]

[0057] In formula (1), H is the virtual inertia of VSG; D is the virtual damping of VSG; It is the synchronous angular velocity of the grid-connected point of the renewable energy grid-connected converter.

[0058] In order to enable the new energy grid-connected converter VSG to have frequency regulation capability, an active power-frequency droop scheme is adopted, and the control equation can be expressed as:

[0059] P m =P ref +m(ω-ω0) (2)

[0060] In formula (2), m is the active power-frequency droop coefficient. Substituting formula (2) into formula (1), the control model of the virtual speed regulator of the new energy grid-connected converter VSG is obtained as follows:

[0061]

[0062] VSG can also simulate the excitation current control method of synchronous generator to achieve voltage amplitude regulation and has excitation regulation inertia. Analogous to the VSG rotor mechanical equation of the new energy grid-connected converter, it adopts a fast excitation method to flexibly adjust the output reactive power of the new energy grid-connected converter. The regulation equation is:

[0063]

[0064] In formula (4): K s is the voltage regulation coefficient; T a is the delay constant, which can avoid transient voltage shocks during the regulation process; s is the Laplace operator.

[0065] like Figure 2 As shown, I is the output three-phase current i of the new energy grid-connected converter VSG abc Amplitude; U is the grid-side voltage u abc Amplitude; Z is the equivalent impedance, which is the output impedance Z of the new energy grid-connected converter f And the transmission line impedance Z g Composition, can be expressed as:

[0066]

[0067] In formula (5), R is the equivalent resistance; X is the equivalent inductive reactance; in the equivalent impedance of the new energy grid-connected converter line, the equivalent inductive reactance is much larger than the equivalent resistance.

[0068] according to Figure 2 , based on Kirchhoff's voltage law:

[0069]

[0070] Define T abc→dq0is the Park transformation matrix, and the equation (6) is transformed from the three-phase stationary coordinate system to the two-phase rotating coordinate system. The dq axis current coupling component is introduced, and the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system can be obtained as follows:

[0071]

[0072] In the dq two-phase coordinate system, the output voltage of the new energy grid-connected converter VSG and the grid-connected voltage have the following relationship:

[0073]

[0074] When the VSG control system of the new energy grid-connected converter is running stably, the output power of the VSG can be expressed as:

[0075]

[0076] like Figure 3 As shown, the present invention adopts energy composition function to analyze the transient energy change process of the new energy grid-connected converter VSG when the frequency is adjusted. The energy composition function of the new energy grid-connected converter VSG can be expressed as:

[0077]

[0078] In formula (10): W d , W s , W d is the energy required for kinetic energy, potential energy and damping of the new energy grid-connected converter VSG; δ0 is the initial virtual power angle of the new energy grid-connected converter VSG; P δ P is the output power of the new energy grid-connected converter VSG when the virtual power angle is δ; δ0 When the virtual power angle is the initial power angle, the new energy grid-connected converter VSG output power.

[0079] When the VSG frequency of the renewable energy grid-connected converter is adjusted, according to the relationship between ω and ω0, it can be divided into: ω>ω0 stage and ω<ω0 stage. The ω>ω0 stage includes stage a and stage b, where: dω / dt>0 in stage a, dω / dt<0 in stage b. The ω<ω0 stage includes stage c and stage d, where: dω / dt<0 in stage c; dω / dt>0 in stage d. In stage a, W d Gradually increasing, W s Gradually decreases, and enters stage b under the action of kinetic energy, W d Gradually decrease, W s Gradually increases, and reciprocates under the action of potential energy. Considering the VSG damping effect energy W d , new energy grid-connected converter VSG frequency regulation total energy W zDuring the oscillation process, 2 gradually decreases, and the frequency regulation of the renewable energy grid-connected converter VSG tends to be stable until the frequency stabilizes.

[0080] Based on this, the present invention proposes a method of increasing the virtual moment of inertia H in the a stage and the d stage, i.e., the virtual angular frequency acceleration stage, to constrain the increase of the virtual angular frequency and reduce the virtual angular frequency adjustment deviation, while simultaneously increasing the virtual damping coefficient D to reduce the virtual angular frequency overshoot, and suppressing the frequency oscillation instability caused by the excessive virtual moment of inertia H. In the b stage and the c stage, i.e., the virtual angular frequency deceleration stage, the virtual moment of inertia H is reduced to quickly restore the frequency to a stable value, and at the same time, the virtual damping coefficient D is synchronously reduced to reduce the dynamic adjustment time of the new energy grid-connected converter VSG control system, so that the frequency adjustment of the new energy grid-connected converter VSG tends to be stable more quickly. The present invention introduces the frequency change rate to characterize the virtual inertia, and the new adaptive virtual inertia H i It can be expressed as:

[0081]

[0082] In formula (11), H0 is the initial value of the virtual inertia of the new energy grid-connected converter VSG, corresponding to the rated virtual inertia when not participating in frequency regulation; k i is the virtual inertia adjustment coefficient. i Adaptive adjustment, virtual damping D i According to H i Automatic adjustment, H i and D i Joint coordinated control can effectively reduce the oscillation frequency during VSG frequency adjustment of the new energy grid-connected converter and maintain the stability of VSG frequency regulation.

[0083] Example 3

[0084] like Figure 4 As shown, the present invention provides a frequency rotation inertia control system for a high-proportion new energy power grid, comprising:

[0085] The first equation building module builds the virtual rotor motion equation for VSG control of the new energy grid-connected converter;

[0086] The second equation building module performs frequency droop control on the active power in the virtual rotor motion equation obtained in the first equation building module to obtain an active power-frequency droop equation;

[0087] The mathematical model derivation module uses Kirchhoff's voltage law and considers the coupling components of the dq axis current to derive the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system;

[0088] The calculation module calculates the output power of the VSG when the VSG control system of the new energy grid-connected converter is in stable operation based on the mathematical model obtained by the mathematical model derivation module;

[0089] The third equation building module uses the output power obtained by the calculation module and the virtual rotor motion equation of the first equation building module, and adopts the energy composition function to analyze the transient energy change process of the new energy grid-connected converter VSG during frequency adjustment;

[0090] The analysis and processing module, based on the relationship between the current angular frequency and the initial angular frequency, combines the third equation to establish the energy composition function analysis of the module, as well as the frequency adjustment change rate of the new energy grid-connected converter VSG in the acceleration and deceleration stages of the virtual angular frequency, and introduces the frequency change rate to characterize the virtual inertia, and finally obtains a new adaptive virtual inertia;

[0091] The adjustment module introduces the new adaptive virtual inertia obtained by the analysis and processing module into the virtual rotor motion equation of the first equation establishment module, and obtains the high-proportion new energy grid frequency rotation inertia control equation for reducing the oscillation frequency during the frequency adjustment of the new energy grid-connected converter VSG, thereby realizing the adjustment of the new energy grid frequency.

[0092] In this embodiment, in the first equation building module, a virtual rotor motion equation controlled by the new energy grid-connected converter VSG is established, including: Where: H is the VSG virtual inertia; D is the VSG virtual damping; ω0 is the synchronous angular velocity of the grid-connected converter of the new energy grid; P m Output virtual mechanical power for VSG; P e is the actual output value of active and reactive power of the new energy grid-connected converter system; δ and ω are the virtual power angle and virtual electrical angular velocity of VSG, respectively.

[0093] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0094] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A frequency moment of inertia control method for a high proportion of new energy power grid, characterized in that: The following steps are involved: 1) Establish the virtual rotor motion equation of the VSG control of the new energy grid-connected converter; 2) performing frequency droop control on the active power in the virtual rotor motion equation obtained in step 1) to obtain an active power-frequency droop equation; 3) Using Kirchhoff's voltage law and considering the coupled components of the dq axis current, the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system is derived; 4) Based on the mathematical model obtained in step 3), calculate the output power of the VSG when the VSG control system of the new energy grid-connected converter is in stable operation; 5) Using the output power obtained in step 4) and the virtual rotor motion equation in step 1), the energy composition function is used to analyze the transient energy change process of the new energy grid-connected converter VSG during frequency adjustment; 6) According to the relationship between the current angular frequency and the initial angular frequency, combined with the energy composition function analysis in step 5), and the frequency adjustment change rate of the new energy grid-connected converter VSG in the acceleration and deceleration stages of the virtual angular frequency, the frequency change rate is introduced to characterize the virtual inertia, and finally a new adaptive virtual inertia is obtained; 7) The new adaptive virtual inertia obtained in step 6) is introduced into the virtual rotor motion equation of step 1) to obtain a high-proportion new energy grid frequency rotation inertia control equation for reducing the oscillation frequency during frequency adjustment of the new energy grid-connected converter VSG, thereby realizing the adjustment of the new energy grid frequency.

2. The frequency moment of inertia control method for a high-proportion new energy power grid according to claim 1 is characterized in that: Step 1) Establishing the virtual rotor motion equation of the new energy grid-connected converter VSG control, including: Where: H is the VSG virtual inertia; D is the VSG virtual damping; ω0 is the synchronous angular velocity of the grid-connected converter of the new energy grid; P m Output virtual mechanical power for VSG; P e is the actual output value of active and reactive power of the new energy grid-connected converter system; δ and ω are the virtual power angle and virtual electrical angular velocity of VSG, respectively.

3. The frequency moment of inertia control method for a high-proportion new energy grid according to claim 2 is characterized in that: The specific implementation method of step 2) is: perform frequency droop control on the active power in the virtual rotor motion equation obtained in step 1) to obtain the active power-frequency droop equation: P m =P ref +m(ω-ω0); where: m is the active power-frequency droop coefficient; P ref is the active power target value.

4. The frequency moment of inertia control method for a high-proportion new energy grid according to claim 3 is characterized in that: The specific implementation method of step 3) is: using Kirchhoff's voltage law and considering the coupling component of the dq axis current, deriving the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system, including: Where: L is the equivalent inductance of the new energy grid-connected converter; u abc is the three-phase voltage at the grid connection point, i.e., the grid-side voltage; e abc 、i abc is the AC three-phase output voltage and current of the new energy grid-connected converter VSG; R is the equivalent resistance of the new energy grid-connected converter; define T abc→dq0 The Park transformation matrix is ​​introduced, and the dq axis current coupling component is introduced to obtain the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system: In the dq two-phase coordinate system, the output voltage and grid-connected voltage of the new energy grid-connected converter VSG exist:

5. The frequency moment of inertia control method for a high-proportion new energy grid according to claim 4 is characterized in that: The specific implementation method of step 4) is: based on the mathematical model obtained in step 3), calculate the output power of VSG when the VSG control system of the new energy grid-connected converter is running stably:

6. The frequency moment of inertia control method for a high-proportion new energy grid according to claim 5 is characterized in that: The specific implementation method of step 5) is: using the output power obtained in step 4) and the virtual rotor motion equation in step 1), the energy composition function is used to analyze the transient energy change process of the new energy grid-connected converter VSG during frequency adjustment: Where: W d , W s , W d is the energy required for kinetic energy, potential energy and damping of the new energy grid-connected converter VSG; δ0 is the initial virtual power angle of the new energy grid-connected converter VSG; P δ P is the output power of the new energy grid-connected converter VSG when the virtual power angle is δ; δ0 When the virtual power angle is the initial power angle, the new energy grid-connected converter VSG output power.

7. The frequency moment of inertia control method for a high-proportion new energy grid according to claim 6 is characterized in that: The specific implementation method of step 6) is: according to the relationship between the current angular frequency and the initial angular frequency, combined with the energy composition function analysis of step 5), and the frequency adjustment change rate of the new energy grid-connected converter VSG in the acceleration and deceleration stages of the virtual angular frequency, when the frequency of the new energy grid-connected converter VSG is adjusted, according to the relationship between ω and ω0, it is divided into: ω>ω0 stage and ω<ω0 stage; ω>ω0 stage includes stage a and stage b, wherein: stage a dω / dt>0, stage b dω / dt<0; ω<ω0 stage includes stage c and stage d, wherein: stage c dω / dt<0; stage d ω / dt>0; in stage a, W d Gradually increasing, W s Gradually decreases, and enters stage b under the action of kinetic energy, W d Gradually decrease, W s Gradually increases, and reciprocates under the action of potential energy; considering the VSG damping effect energy W d , new energy grid-connected converter VSG frequency regulation total energy W z During the oscillation process, 2 gradually decreases, and the frequency regulation of the new energy grid-connected converter VSG tends to be stable until the frequency is stable; it is proposed to increase the virtual moment of inertia H in the a stage and the d stage, that is, the virtual angular frequency acceleration stage to constrain the increase of the virtual angular frequency and reduce the virtual angular frequency regulation deviation, and at the same time, increase the virtual damping coefficient D to reduce the virtual angular frequency overshoot, and suppress the frequency oscillation instability caused by the excessive virtual moment of inertia H; in the b stage and the c stage, that is, the virtual angular frequency deceleration stage, reduce the virtual moment of inertia H to quickly restore the frequency to a stable value, and at the same time, reduce the virtual damping coefficient D to reduce the dynamic adjustment time of the new energy grid-connected converter VSG control system, so that the frequency regulation of the new energy grid-connected converter VSG tends to be stable faster; introduce the frequency change rate to characterize the virtual inertia, and obtain a new adaptive virtual inertia: Where: H0 is the initial value of the virtual inertia of the new energy grid-connected converter VSG, corresponding to the rated virtual inertia when not participating in frequency regulation; k i is the virtual inertia adjustment coefficient; when the new virtual inertia H i Adaptive adjustment, virtual damping D i According to H i Automatic adjustment, H i and D i Joint coordinated control can reduce the oscillation frequency during VSG frequency adjustment of the new energy grid-connected converter and maintain the stability of VSG frequency regulation.

8. The frequency moment of inertia control method for a high-proportion new energy grid according to claim 7 is characterized in that: The specific implementation method of step 7) is: introduce the new adaptive virtual inertia obtained in step 6) into the virtual rotor motion equation of step 1), and obtain the high-proportion new energy grid frequency rotation inertia control equation for reducing the oscillation frequency during the frequency adjustment of the new energy grid-connected converter VSG:

9. A frequency inertia control system for a high proportion of new energy power grid, characterized in that: include: The first equation building module builds the virtual rotor motion equation for VSG control of the new energy grid-connected converter; The second equation building module performs frequency droop control on the active power in the virtual rotor motion equation obtained in the first equation building module to obtain an active power-frequency droop equation; The mathematical model derivation module uses Kirchhoff's voltage law and considers the coupling components of the dq axis current to derive the mathematical model of the output voltage of the VSG control system of the new energy grid-connected converter in the dq two-phase coordinate system; The calculation module calculates the output power of the VSG when the VSG control system of the new energy grid-connected converter is in stable operation based on the mathematical model obtained by the mathematical model derivation module; The third equation building module uses the output power obtained by the calculation module and the virtual rotor motion equation of the first equation building module, and adopts the energy composition function to analyze the transient energy change process of the new energy grid-connected converter VSG during frequency adjustment; The analysis and processing module, based on the relationship between the current angular frequency and the initial angular frequency, combines the third equation to establish the energy composition function analysis of the module, as well as the frequency adjustment change rate of the new energy grid-connected converter VSG in the acceleration and deceleration stages of the virtual angular frequency, and introduces the frequency change rate to characterize the virtual inertia, and finally obtains a new adaptive virtual inertia; The adjustment module introduces the new adaptive virtual inertia obtained by the analysis and processing module into the virtual rotor motion equation of the first equation establishment module, and obtains the high-proportion new energy grid frequency rotation inertia control equation for reducing the oscillation frequency during the frequency adjustment of the new energy grid-connected converter VSG, thereby realizing the adjustment of the new energy grid frequency.

10. A frequency inertia control system for a high-proportion new energy grid according to claim 9, characterized in that: In the first equation building module, the virtual rotor motion equation of the new energy grid-connected converter VSG control is established, including: Where: H is the VSG virtual inertia; D is the VSG virtual damping; ω0 is the synchronous angular velocity of the grid-connected converter of the new energy grid; P m Output virtual mechanical power for VSG; P e is the actual output value of active and reactive power of the new energy grid-connected converter system; δ and ω are the virtual power angle and virtual electrical angular velocity of VSG, respectively.

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