Method, system, equipment and medium for parameter simulation analysis of network construction type converter

Abstract

The invention belongs to the technical field of new energy power systems, and discloses a net-building type converter parameter simulation analysis method, system, equipment and medium, and the method comprises the steps: building an equivalent transfer function and a damping torque model of a net-building type converter based on a damping torque theory, and defining a damping torque and a synchronous torque through the generation and conversion of a characteristic equation; establishing a converter voltage-current relational expression based on the dynamic equation of the grid-forming converter, and deducing a damping torque of the grid-forming converter containing a complete control loop through linearization processing of the relational expression; and simulating the damping characteristics of the network-forming converter containing the complete control loop, and evaluating the influence degree of the outer loop control parameters on the damping torque by analyzing the damping torque under different outer loop bandwidths. The invention provides the damping torque model for optimizing the network construction type outer ring control parameters, so that modeling of a complex feedback link in a damping torque equivalent model is avoided, and a brand new thought is provided for analyzing the outer ring control parameter optimization problem.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy power systems, and in particular to a parameter simulation analysis method, system, equipment and medium for a grid-connected converter. Background Art

[0002] With the increasing installed capacity of photovoltaic, wind power and other new energy sites in my country, my country is gradually transitioning to a "double-high" power system with a high proportion of renewable energy and a high proportion of power electronic equipment. However, due to the lack of frequency and inertial support for the grid-connected new energy, the power system connected to the grid with new energy will experience strong oscillations or even instability. The GFM converter technology that currently uses the simulated synchronous machine operating characteristics has become the subject of extensive research in the industry because it can improve the system damping level and has great potential in improving the system inertia.

[0003] At present, the main analysis methods for the stability of renewable energy power systems are numerical simulation, modal analysis, impedance analysis, and damping torque analysis. Numerical analysis has a wide range of applications and strong universality, but it requires high computer computing power and lacks the ability to analyze internal dynamic processes. Modal analysis, also known as eigenvalue analysis, can basically determine the stability of the system, but it cannot analyze the internal mechanism of a single oscillation mode. Impedance analysis can only summarize phenomena such as the law of stability changes, and it is difficult to reveal the internal physical causes of system instability. Therefore, damping torque analysis combines state space equations and eigenvalue methods to analyze the problem of low-frequency oscillation after renewable energy is connected to the grid. In current research, the study of converter control parameters is mainly based on impedance analysis and modal analysis.

[0004] Therefore, how to provide a parameter simulation and analysis method, system, equipment and medium for a grid-connected converter is a problem that needs to be solved urgently. Summary of the invention

[0005] The embodiments of the present invention provide a parameter simulation analysis method, system, device and medium for a grid-connected converter to solve the above-mentioned technical problems existing in the prior art.

[0006] In order to have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended to be a general review, nor is it intended to identify key / important components or to delineate the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0007] According to a first aspect of an embodiment of the present invention, a parameter simulation and analysis method for a grid-connected converter is provided.

[0008] In one embodiment, the grid-type converter parameter simulation and analysis method comprises:

[0009] Based on the damping torque theory, the equivalent transfer function and damping torque model of the grid-connected converter are established, and the damping torque and synchronous torque are defined by generating and transforming the characteristic equation.

[0010] Based on the dynamic equation of the grid-type converter, the converter voltage-current relationship is established, and the damping torque of the grid-type converter with a complete control loop is derived by linearizing the relationship.

[0011] The damping characteristics of the grid-type converter with a complete control loop are simulated, and the influence of the outer loop control parameters on the damping torque is evaluated by analyzing the damping torque under different outer loop bandwidths.

[0012] In one embodiment, based on the damping torque theory, the equivalent transfer function and damping torque model of the grid-type converter are established, and the damping torque and the synchronous torque are defined by generating and converting the characteristic equation, including:

[0013] The original transfer function of the sixth-order synchronous machine model is obtained, the electromagnetic power and the power angle variation are retained, the rotor motion equation transfer function is used as the forward transfer function, and the rest is used as the feedback transfer function. The equivalent transfer function of the grid-type converter is converted and the characteristic equation of the grid-type converter is generated.

[0014] Substituting the forward transfer function into the characteristic equation, defining the solution result as the characteristic root, and converting the characteristic equation into an approximate characteristic equation by selecting a specific characteristic root and inputting it into the feedback transfer function;

[0015] Based on the approximate analysis of the approximate characteristic equation, the result with the same phase as the velocity offset is defined as the damping torque, and the result with the same phase as the angle offset is defined as the synchronizing torque.

[0016] In one embodiment, the formula of the approximate characteristic equation is:

[0017]

[0018] Where H is the synchronization coefficient; D is the damping coefficient; s is the complex frequency domain variable; H D (jω0) is the imaginary part of the feedback transfer function; j is the imaginary unit; ω0 is the rated angular frequency of the system.

[0019] In one embodiment, the dynamic equation of the grid-type converter is based on which the converter voltage-current relationship is established, and the damping torque of the grid-type converter containing a complete control loop is derived by linearizing the relationship, including:

[0020] Based on the sixth-order synchronous machine model, the damping torque equation of the grid-type converter with a complete control loop is established, and the converter voltage-current relationship is generated according to the dynamic equation of the grid-type converter.

[0021] The voltage-current relationship of the converter is linearized at the equilibrium point to obtain a dq axis current array, and the grid connection point voltage is linearized to obtain a dq axis voltage array;

[0022] The dq axis current array and the dq axis voltage array are combined and inserted into the damping torque equation, and the dq axis impedance of the grid-type converter is derived by solving the equation.

[0023] In one embodiment, the converter voltage-current relationship is:

[0024]

[0025] Where, ω0 is the rated angular frequency of the system; L f is the filter inductor; C f is the filter capacitor; U td is the d-axis component of the grid-connected point voltage; U tq is the q-axis component of the grid-connected point voltage; I d I is the current inner loop d-axis control current; q E is the current inner loop q axis control current; d PI is the PWM control d-axis command value; cc (s) is the current inner loop PI control link; PI vc (s) is the voltage outer loop PI control link; f VF It is the voltage feedforward filter link.

[0026] In one embodiment, the damping torque equation is:

[0027]

[0028] In the formula, ΔT GFM is the damping torque of the grid-type converter; ΔP is the electromagnetic power; U t is the grid voltage amplitude; Z GFMd (s) is the d-axis impedance of the grid-type converter; Z GFMq (s) is the q-axis impedance of the grid-type converter; Δδ is the angle change of the damping torque; u td0 is the steady-state value of the grid-connected point voltage d-axis; Δu d is the change in the voltage d-axis component; Δu q is the change in the voltage q-axis component; Δi d is the change in the d-axis component of the current; Δi q is the change in the q-axis component of the current.

[0029] In one embodiment, the simulation includes a damping characteristic of a grid-type converter having a complete control loop, and evaluating the influence of the outer loop control parameters on the damping torque by analyzing the damping torque under different outer loop bandwidths, including:

[0030] Use simulation software to simulate the damping characteristics of the grid-type converter with a complete control loop, and generate a Bode diagram showing the damping characteristics of the grid-type converter;

[0031] The initial complex frequency domain variables are set and input into the characteristic equation of the damping torque model. The corresponding damping torque vector is obtained by adjusting the outer loop bandwidth. The value of the outer loop bandwidth is adjusted in turn to measure the matrix dominant eigenvalue of the power grid system. According to the numerical change trend of the matrix dominant eigenvalue, the influence of the numerical change of the outer loop bandwidth on the damping torque is evaluated.

[0032] According to a second aspect of an embodiment of the present invention, a parameter simulation and analysis system for a grid-connected converter is provided.

[0033] In one embodiment, the grid-type converter parameter simulation and analysis system comprises:

[0034] Theoretical modeling module, which is used to establish the equivalent transfer function and damping torque model of the grid-type converter based on the damping torque theory, and define the damping torque and synchronous torque through the generation and conversion of characteristic equations;

[0035] A derivation and transformation module is used to establish a voltage-current relationship of the converter based on the dynamic equation of the grid-type converter, and to derive the damping torque of the grid-type converter containing a complete control loop by linearizing the relationship;

[0036] The simulation analysis module is used to simulate the damping characteristics of the grid-type converter with a complete control loop. By analyzing the damping torque under different outer loop bandwidths, the influence of the outer loop control parameters on the damping torque is evaluated.

[0037] In one embodiment, the theoretical modeling module includes: a characteristic equation module, an equation conversion module and a torque definition module, wherein:

[0038] The characteristic equation module is used to obtain the original transfer function of the sixth-order synchronous machine model, retain the electromagnetic power and the power angle change, use the rotor motion equation transfer function as the forward transfer function, and the rest as the feedback transfer function, convert to obtain the equivalent transfer function of the grid-forming converter, and generate the characteristic equation of the grid-forming converter;

[0039] The equation conversion module is used to substitute the forward transfer function into the characteristic equation, define the solution result as the characteristic root, and convert the characteristic equation into an approximate characteristic equation by selecting a specific characteristic root and inputting it into the feedback transfer function;

[0040] The torque definition module is used to define the result with the same phase as the speed offset as the damping torque and define the result with the same phase as the angle offset as the synchronization torque based on the approximate analysis of the approximate characteristic equation.

[0041] In one embodiment, the formula of the approximate characteristic equation is:

[0042]

[0043] Where H is the synchronization coefficient; D is the damping coefficient; s is the complex frequency domain variable; H D (jω0) is the imaginary part of the feedback transfer function; j is the imaginary unit; ω0 is the rated angular frequency of the system.

[0044] In one embodiment, the derivation and transformation module includes: a relational module, a linearization module and a solution derivation module, wherein:

[0045] The relational expression module is used to establish a damping torque equation of a grid-type converter containing a complete control loop based on a sixth-order synchronous machine model, and to generate a converter voltage-current relational expression according to a dynamic equation of the grid-type converter;

[0046] The linearization module is used to linearize the voltage-current relationship of the converter at the equilibrium point to obtain a dq axis current array, and linearize the grid connection point voltage to obtain a dq axis voltage array;

[0047] The solution derivation module is used to combine the dq axis current array and the dq axis voltage array and then insert them into the damping torque equation, and derive the dq axis impedance of the grid-type converter by solving the equation.

[0048] In one embodiment, the converter voltage-current relationship is:

[0049]

[0050] Where, ω0 is the rated angular frequency of the system; L f is the filter inductor; C f is the filter capacitor; U td is the d-axis component of the grid-connected point voltage; U tq is the q-axis component of the grid-connected point voltage; I d I is the current inner loop d-axis control current; q E is the current inner loop q axis control current; dPI is the PWM control d-axis command value; cc (s) is the current inner loop PI control link; PI vc (s) is the voltage outer loop PI control link; f VF It is the voltage feedforward filter link.

[0051] In one embodiment, the damping torque equation is:

[0052]

[0053] In the formula, ΔT GFM is the damping torque of the grid-type converter; ΔP is the electromagnetic power; U t is the grid voltage amplitude; Z GFMd (s) is the d-axis impedance of the grid-type converter; Z GFMq (s) is the q-axis impedance of the grid-type converter; Δδ is the angle change of the damping torque; u td0 is the steady-state value of the grid-connected point voltage d-axis; Δu d is the change in the voltage d-axis component; Δu q is the change in the voltage q-axis component; Δi d is the change in the d-axis component of the current; Δi q is the change in the q-axis component of the current.

[0054] In one embodiment, the simulation analysis module includes: a software simulation module and a numerical evaluation module, wherein:

[0055] The software simulation module is used to simulate the damping characteristics of the grid-type converter containing a complete control loop using simulation software, and generate a Bode diagram showing the damping characteristics of the grid-type converter;

[0056] The numerical evaluation module is used to set initial complex frequency domain variables, input them into the characteristic equation of the damping torque model, obtain the corresponding damping torque vector by adjusting the outer loop bandwidth, and adjust the value of the outer loop bandwidth in turn to measure the matrix dominant eigenvalue of the power grid system. According to the numerical change trend of the matrix dominant eigenvalue, the influence of the numerical change of the outer loop bandwidth on the damping torque is evaluated.

[0057] According to a third aspect of an embodiment of the present invention, a computer device is provided.

[0058] In some embodiments, the computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0059] According to a fourth aspect of embodiments of the present invention, a computer-readable storage medium is provided.

[0060] In one embodiment, the computer-readable storage medium stores a computer program, and the computer program implements the steps of the above method when executed by a processor.

[0061] The technical solution provided by the embodiment of the present invention may include the following beneficial effects: by utilizing the grid-type converter technology, the influence of the outer loop control parameters on the damping torque of the grid-type converter is modeled and analyzed using the damping torque method, and a damping torque model for optimizing the grid-type outer loop control parameters is proposed based on the damping torque theory, thereby avoiding modeling of the complex feedback link in the damping torque equivalent model, and suggesting that the influence of the outer loop control parameters on the system stability can be judged by examining the damping torque, which provides a new idea for analyzing the problem of optimizing the outer loop control parameters.

[0062] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0064] Figure 1 is a flow chart of a parameter simulation and analysis method of a grid-connected converter according to an exemplary embodiment;

[0065] Figure 2 is a system block diagram of a grid-type converter parameter simulation and analysis system according to an exemplary embodiment;

[0066] Figure 3 is a structural schematic diagram of a computer device according to an exemplary embodiment;

[0067] Figure 4 is a schematic diagram of an original transfer function of a classic sixth-order synchronous machine model according to an exemplary embodiment;

[0068] Figure 5 is a schematic diagram of an equivalent transfer function according to an exemplary embodiment;

[0069] Figure 6 is a complete control loop GFM converter impedance characteristic shown according to an exemplary embodiment;

[0070] Figure 7 is a comparison of damping torque vectors under two different outer loop bandwidths according to an exemplary embodiment;

[0071] Figure 8 The diagram shows the change of the dominant characteristic value of the system under different outer loop bandwidths according to an exemplary embodiment. DETAILED DESCRIPTION

[0072] The following description and accompanying drawings fully illustrate the specific embodiments of this article so that those skilled in the art can practice them. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of this article includes the entire scope of the claims, as well as all available equivalents of the claims. Herein, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the structure, device or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such structure, device or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the structure, device or equipment including the elements. Each embodiment is described in a progressive manner herein, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other.

[0073] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0074] As used herein, unless otherwise specified, the term "plurality" means two or more than two.

[0075] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0076] In this article, the term "and / or" is a description of the association relationship between objects, indicating that three relationships may exist. For example, A and / or B means: A or B, or, A and B.

[0077] It should be understood that, although the various steps in the flow chart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0078] Each module in the device or system of the present application can be implemented in whole or in part by software, hardware, or a combination thereof. The above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above modules.

[0079] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0080] Figure 1 An embodiment of a parameter simulation and analysis method for a grid-type converter according to the present invention is shown.

[0081] In this optional embodiment, the grid-type converter parameter simulation and analysis method includes:

[0082] Step S101, based on the damping torque theory, an equivalent transfer function and a damping torque model of a grid-connected converter are established, and the damping torque and the synchronous torque are defined by generating and converting characteristic equations;

[0083] Step S103: based on the dynamic equation of the grid-type converter, establish a converter voltage-current relationship, and derive the damping torque of the grid-type converter containing a complete control loop by linearizing the relationship;

[0084] Step S105 , simulating the damping characteristics of the grid-type converter containing a complete control loop, and evaluating the influence of the outer loop control parameters on the damping torque by analyzing the damping torque under different outer loop bandwidths.

[0085] In this optional embodiment, when the equivalent transfer function and damping torque model of the mesh-type converter are established based on the damping torque theory, and the damping torque and the synchronous torque are defined by generating and converting the characteristic equation, the original transfer function of the sixth-order synchronous machine model can be obtained, the electromagnetic power and the power angle change are retained, the rotor motion equation transfer function is used as the forward transfer function, and the rest is used as the feedback transfer function to obtain the equivalent transfer function of the mesh-type converter, and generate the characteristic equation of the mesh-type converter; the forward transfer function is substituted into the characteristic equation, and the solution result is defined as the characteristic root, and the characteristic equation is converted into an approximate characteristic equation by selecting a specific characteristic root and inputting it into the feedback transfer function; based on the approximate analysis of the approximate characteristic equation, the result with the same phase as the speed offset is defined as the damping torque, and the result with the same phase as the angle offset is defined as the synchronous torque.

[0086] In this optional embodiment, the formula of the approximate characteristic equation is:

[0087]

[0088] Where H is the synchronization coefficient; D is the damping coefficient; s is the complex frequency domain variable; H D (jω0) is the imaginary part of the feedback transfer function; j is the imaginary unit; ω0 is the rated angular frequency of the system.

[0089] In this optional embodiment, when establishing the voltage-current relationship of the converter based on the dynamic equation of the grid-type converter, and deriving the damping torque of the grid-type converter containing a complete control loop by linearizing the relationship, a damping torque equation of the grid-type converter containing a complete control loop can be established based on a sixth-order synchronous machine model, and the voltage-current relationship of the converter can be generated according to the dynamic equation of the grid-type converter; the voltage-current relationship of the converter is linearized at the equilibrium point to obtain a dq-axis current array, and the grid-connected point voltage is linearized to obtain a dq-axis voltage array; the dq-axis current array and the dq-axis voltage array are combined and inserted into the damping torque equation, and the dq-axis impedance of the grid-type converter is derived by solving the equation.

[0090] In this optional embodiment, the formula of the converter voltage-current relationship is:

[0091]

[0092] Where, ω0 is the rated angular frequency of the system; L f is the filter inductor; C f is the filter capacitor; U td is the d-axis component of the grid-connected point voltage; U tq is the q-axis component of the grid-connected point voltage; I d I is the current inner loop d-axis control current;q E is the current inner loop q axis control current; d PI is the PWM control d-axis command value; cc (s) is the current inner loop PI control link; PI vc (s) is the voltage outer loop PI control link; f VF It is the voltage feedforward filter link.

[0093] In this optional embodiment, the damping torque equation is:

[0094]

[0095] In the formula, ΔT GFM is the damping torque of the grid-type converter; ΔP is the electromagnetic power; U t is the grid voltage amplitude; Z GFMd (s) is the d-axis impedance of the grid-type converter; Z GFMq (s) is the q-axis impedance of the grid-type converter; Δδ is the angle change of the damping torque; u td0 is the steady-state value of the grid-connected point voltage d-axis; Δu d is the change in the voltage d-axis component; Δu q is the change in the voltage q-axis component; Δi d is the change in the d-axis component of the current; Δi q is the change in the q-axis component of the current.

[0096] In this optional embodiment, when simulating the damping characteristics of a grid-type converter containing a complete control loop and analyzing the damping torque under different outer loop bandwidths to evaluate the influence of the outer loop control parameters on the damping torque, simulation software can be used to simulate the damping characteristics of the grid-type converter containing a complete control loop to generate a Bode plot showing the damping characteristics of the grid-type converter; initial complex frequency domain variables are set and input into the characteristic equation of the damping torque model, and the corresponding damping torque vector is obtained by adjusting the outer loop bandwidth, and the value of the outer loop bandwidth is adjusted in turn, and the matrix dominant eigenvalue of the power grid system is measured, and the influence of the numerical change of the outer loop bandwidth on the damping torque is evaluated according to the numerical change trend of the matrix dominant eigenvalue.

[0097] Figure 2 An embodiment of a grid-type converter parameter simulation and analysis system of the present invention is shown.

[0098] In this optional embodiment, the grid-type converter parameter simulation and analysis system includes:

[0099] Theoretical modeling module 201 is used to establish an equivalent transfer function and a damping torque model of a grid-type converter based on the damping torque theory, and to define the damping torque and the synchronous torque by generating and converting the characteristic equation;

[0100] A derivation and transformation module 203 is used to establish a voltage-current relationship of the converter based on the dynamic equation of the grid-type converter, and to derive the damping torque of the grid-type converter containing a complete control loop by linearizing the relationship;

[0101] The simulation analysis module 205 is used to simulate the damping characteristics of the grid-type converter containing a complete control loop, and evaluate the influence of the outer loop control parameters on the damping torque by analyzing the damping torque under different outer loop bandwidths.

[0102] In this optional embodiment, the theoretical modeling module 201 includes: a characteristic equation module (not shown in the figure), an equation conversion module (not shown in the figure) and a torque definition module (not shown in the figure), wherein the characteristic equation module is used to obtain the original transfer function of the sixth-order synchronous machine model, retain the electromagnetic power and the power angle change, use the rotor motion equation transfer function as the forward transfer function, and the rest as the feedback transfer function, convert to obtain the equivalent transfer function of the grid-type converter, and generate the characteristic equation of the grid-type converter; the equation conversion module is used to substitute the forward transfer function into the characteristic equation, define the solution result as the characteristic root, and convert the characteristic equation into an approximate characteristic equation by selecting a specific characteristic root and inputting it into the feedback transfer function; the torque definition module is used for approximate analysis based on the approximate characteristic equation, define the result with the same phase as the speed offset as the damping torque, and define the result with the same phase as the angle offset as the synchronous torque.

[0103] In this optional embodiment, the derivation and transformation module 203 includes: a relational module (not shown in the figure), a linearization module (not shown in the figure) and a solution derivation module (not shown in the figure), wherein the relational module is used to establish a damping torque equation of a grid-type converter containing a complete control loop based on a sixth-order synchronous machine model, and generate a converter voltage-current relational equation according to the dynamic equation of the grid-type converter; the linearization module is used to linearize the converter voltage-current relational equation at the equilibrium point to obtain a dq-axis current array, and linearize the grid-connected point voltage to obtain a dq-axis voltage array; the solution derivation module is used to combine the dq-axis current array and the dq-axis voltage array and then insert them into the damping torque equation, and derive the dq-axis impedance of the grid-type converter by solving the equation.

[0104] In this optional embodiment, the simulation analysis module 205 includes: a software simulation module (not shown in the figure) and a numerical evaluation module (not shown in the figure), wherein the software simulation module is used to simulate the damping characteristics of the grid-type converter containing a complete control loop using simulation software to generate a Bode diagram showing the damping characteristics of the grid-type converter; the numerical evaluation module is used to set initial complex frequency domain variables, input them into the characteristic equation of the damping torque model, obtain the corresponding damping torque vector by adjusting the outer loop bandwidth, and adjust the value of the outer loop bandwidth in turn, measure the matrix dominant eigenvalue of the power grid system, and evaluate the influence of the numerical change of the outer loop bandwidth on the damping torque according to the numerical change trend of the matrix dominant eigenvalue.

[0105] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0106] In order to solve the problems existing in the current analysis methods of the stability of new energy power systems, the present invention starts from the damping torque analysis method, models the damping torque of the GFM converter (grid-type converter) with grid-type vector control, and analyzes the influence of the outer loop control parameters on it. First, according to the damping torque theory, the damping torque of the GFM converter with grid-type vector control is modeled according to the classic sixth-order synchronous machine model. Subsequently, the damping torque of the GFM converter containing a complete control loop is derived according to the dynamic equation of the grid-type converter. Finally, the damping characteristics of the GFM converter are studied using simulation software, and the influence of the outer loop control parameters on the system stability is judged by analyzing the damping torque under different outer loop bandwidths, and the correctness of the theory is verified by examining the dominant eigenvalue method.

[0107] In order to achieve the above object, the present invention adopts the following technical solution:

[0108] 1. Theoretical analysis of damping torque

[0109] For the original transfer function (such as Figure 4 As shown), retaining Δδ and ΔP e , taking the rotor motion equation transfer function as the forward transfer function and the rest as the feedback transfer function, the equivalent transfer function can be obtained (such as Figure 5 shown).

[0110] Among them, ΔP m The mechanical power input to the system; ΔP e is the electromagnetic power. The characteristic equation of this model can be expressed as follows:

[0111] 1+L D (s)=0 (1)

[0112] Where, L D (s) = G D (s)HD (s), H D (s) is the feedback transfer function, where the forward transfer function G D (s) is expressed as:

[0113]

[0114] Where H is the synchronization coefficient, D is the damping coefficient, and s is the complex frequency domain variable.

[0115] Substituting equation (2) into equation (1) and transforming it, we can get:

[0116] H 2 +Ds+H D (s)=0 (3)

[0117] A solution of formula (3) can be expressed as:

[0118] s i =σ i +jω i (4)

[0119] For a particular solution s i , satisfying σ i <<ω i , we can let s = jω i Substitute it into H D (s) In the analytical formula, the approximate characteristic equation can be obtained by approximating formula (3), as follows:

[0120]

[0121] in,

[0122]

[0123] Where, T D and T K They are the damping torque and synchronizing torque defined using the traditional definition method respectively.

[0124] The two solutions s1 and s2 of the formula can be expressed as:

[0125]

[0126] According to the form of formula (6), T D Defined as the damping torque, T K is the synchronous torque, by analyzing H D (jω i ) can be used to approximately determine the impact of different control links in the system on damping.

[0127] 2. Derivation of damping torque of GFM converter with complete control loop

[0128] Following the classic sixth-order synchronous machine model, the damping torque of the GFM converter with a complete control loop is derived.

[0129] According to the classic sixth-order synchronous machine model, the damping torque can be expressed as follows:

[0130] ΔT SG ≈ΔP e =u d0 Δi d +u q0 Δi q +i d0 Δu d +i q0 Δu q (8)

[0131] In the formula, ΔT SG It represents the change of electromagnetic torque of the classic sixth-order synchronous machine model. GFM It is the change in equivalent electromagnetic torque after damping torque modeling is performed based on the synchronous machine model.

[0132] According to the dynamic equation of the grid-type converter, ignoring the dynamics of the outer loop, we take i dref =1,i qref =0,u dref =1,u qref =0, the converter voltage-current relationship can be obtained as follows:

[0133]

[0134] Linearizing the above equation at the equilibrium point yields:

[0135]

[0136] in:

[0137]

[0138] in:

[0139]

[0140] After linearizing the grid connection point voltage, we can get:

[0141]

[0142] By combining the above equations (10) and (13) and inserting them into the above damping torque equation, we can obtain:

[0143]

[0144] Where K2 = U t i d0 cosδ0,U t is the grid voltage amplitude, Z GFMd (s), Z GFMq (s) represents the dq axis impedance of the GFM converter, and its specific expression is as follows:

[0145]

[0146] 3. Outer loop control parameter optimization

[0147] The above analysis process derives the damping torque of the GFM converter containing a complete control loop. On this basis, the present invention studies the damping characteristics of the GFM converter with a complete control loop, and uses the method of analyzing the dominant eigenvalue to analyze the damping torque containing the complete control loop, and explores the influence of different outer loop control parameters on the damping torque.

[0148] The impedance characteristics of the GFM converter with a complete control loop are as follows: Figure 6 As shown, according to the obtained Bode diagram, it can be seen that in the case of outer loop control, the d-axis provides a large positive damping in the low frequency band (0-10Hz), while the q-axis provides almost no positive damping.

[0149] Substituting s = 2jHz into the above damping torque model and adjusting the outer loop bandwidth can obtain the corresponding damping torque vector. Figure 7 It can be seen that the GFM converter impedance with outer loop control provides a large positive damping, that is, as the outer loop bandwidth increases, the stability of the system increases.

[0150] Adjust the outer loop bandwidth and measure the dominant eigenvalues ​​of the system matrix at 60Hz, 80Hz and 120Hz respectively, such as Figure 8 As shown, it can be found that as the outer loop bandwidth increases, the system stability improves. This is consistent with the above result that the larger the outer loop bandwidth, the larger the positive damping value, proving the feasibility of analyzing the stability of the GFM converter through the damping torque model of the present invention.

[0151] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 3As shown. The computer device includes a processor, a memory and a network interface connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store static information and dynamic information data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the steps in the above method embodiment are implemented.

[0152] Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present invention, and does not constitute a limitation on the computer device to which the solution of the present invention is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0153] In addition, the present invention also provides a computer device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above method embodiment when executing the computer program.

[0154] In addition, the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method embodiment are implemented.

[0155] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0156] The present invention is not limited to the structures which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A parameter simulation and analysis method for a grid-connected converter, characterized in that: include: Based on the damping torque theory, the equivalent transfer function and damping torque model of the grid-connected converter are established, and the damping torque and synchronous torque are defined by generating and transforming the characteristic equation. Based on the dynamic equation of the grid-type converter, the converter voltage-current relationship is established, and the damping torque of the grid-type converter with a complete control loop is derived by linearizing the relationship. The damping characteristics of the grid-type converter with a complete control loop are simulated, and the influence of the outer loop control parameters on the damping torque is evaluated by analyzing the damping torque under different outer loop bandwidths.

2. The parameter simulation and analysis method of a grid-connected converter according to claim 1, characterized in that: Based on the damping torque theory, the equivalent transfer function and damping torque model of the grid-type converter are established, and the damping torque and the synchronous torque are defined by generating and converting the characteristic equation, including: The original transfer function of the sixth-order synchronous machine model is obtained, the electromagnetic power and the power angle variation are retained, the rotor motion equation transfer function is used as the forward transfer function, and the rest is used as the feedback transfer function. The equivalent transfer function of the grid-type converter is converted and the characteristic equation of the grid-type converter is generated. Substituting the forward transfer function into the characteristic equation, defining the solution result as the characteristic root, and converting the characteristic equation into an approximate characteristic equation by selecting a specific characteristic root and inputting it into the feedback transfer function; Based on the approximate analysis of the approximate characteristic equation, the result with the same phase as the velocity offset is defined as the damping torque, and the result with the same phase as the angle offset is defined as the synchronizing torque.

3. The parameter simulation and analysis method of a grid-connected converter according to claim 2, characterized in that: The formula of the approximate characteristic equation is: Where H is the synchronization coefficient; D is the damping coefficient; s is the complex frequency domain variable; H D (jω0) is the imaginary part of the feedback transfer function; j is the imaginary unit; ω0 is the rated angular frequency of the system.

4. The parameter simulation and analysis method of a grid-connected converter according to claim 1, characterized in that: The dynamic equation of the grid-type converter is based on which the voltage-current relationship of the converter is established, and the damping torque of the grid-type converter containing a complete control loop is derived by linearizing the relationship, including: Based on the sixth-order synchronous machine model, the damping torque equation of the grid-type converter with a complete control loop is established, and the converter voltage-current relationship is generated according to the dynamic equation of the grid-type converter. The voltage-current relationship of the converter is linearized at the equilibrium point to obtain a dq axis current array, and the grid connection point voltage is linearized to obtain a dq axis voltage array; The dq axis current array and the dq axis voltage array are combined and inserted into the damping torque equation, and the dq axis impedance of the grid-type converter is derived by solving the equation.

5. The parameter simulation and analysis method of a grid-connected converter according to claim 4, characterized in that: The formula of the converter voltage-current relationship is: Where, ω0 is the rated angular frequency of the system; L f is the filter inductor; C f is the filter capacitor; U td is the d-axis component of the grid-connected point voltage; U tq is the q-axis component of the grid-connected point voltage; I d I is the current inner loop d-axis control current; q E is the current inner loop q axis control current; d PI is the PWM control d-axis command value; cc (s) is the current inner loop PI control link; PI vc (s) is the voltage outer loop PI control link; f VF It is the voltage feedforward filter link.

6. The parameter simulation and analysis method of a grid-connected converter according to claim 4, characterized in that: The damping torque equation is: Where, ΔT GFM is the damping torque of the grid-type converter; ΔP is the electromagnetic power; U t is the grid voltage amplitude; Z GFMd (s) is the d-axis impedance of the grid-type converter; Z GFMq (s) is the q-axis impedance of the grid-type converter; Δδ is the angle change of the damping torque; u td0 is the steady-state value of the grid-connected point voltage d-axis; Δu d is the change in the voltage d-axis component; Δu q is the change in the voltage q-axis component; Δi d is the change in the d-axis component of the current; Δi q is the change in the q-axis component of the current.

7. The parameter simulation and analysis method of a grid-connected converter according to claim 1, characterized in that: The simulation includes the damping characteristics of the grid-type converter with a complete control loop, and the influence of the outer loop control parameters on the damping torque is evaluated by analyzing the damping torque under different outer loop bandwidths, including: Use simulation software to simulate the damping characteristics of the grid-type converter with a complete control loop, and generate a Bode diagram showing the damping characteristics of the grid-type converter; The initial complex frequency domain variables are set and input into the characteristic equation of the damping torque model. The corresponding damping torque vector is obtained by adjusting the outer loop bandwidth. The value of the outer loop bandwidth is adjusted in turn to measure the matrix dominant eigenvalue of the power grid system. According to the numerical change trend of the matrix dominant eigenvalue, the influence of the numerical change of the outer loop bandwidth on the damping torque is evaluated.

8. A grid-type converter parameter simulation and analysis system, characterized in that: include: Theoretical modeling module, which is used to establish the equivalent transfer function and damping torque model of the grid-type converter based on the damping torque theory, and define the damping torque and synchronous torque through the generation and conversion of characteristic equations; A derivation and transformation module is used to establish a voltage-current relationship of the converter based on the dynamic equation of the grid-type converter, and to derive the damping torque of the grid-type converter containing a complete control loop by linearizing the relationship; The simulation analysis module is used to simulate the damping characteristics of the grid-type converter with a complete control loop. By analyzing the damping torque under different outer loop bandwidths, the influence of the outer loop control parameters on the damping torque is evaluated.

9. The grid-type converter parameter simulation and analysis system according to claim 8, characterized in that: The theoretical modeling module includes: a characteristic equation module, an equation conversion module and a torque definition module, wherein: The characteristic equation module is used to obtain the original transfer function of the sixth-order synchronous machine model, retain the electromagnetic power and the power angle change, use the rotor motion equation transfer function as the forward transfer function, and the rest as the feedback transfer function, convert to obtain the equivalent transfer function of the grid-forming converter, and generate the characteristic equation of the grid-forming converter; The equation conversion module is used to substitute the forward transfer function into the characteristic equation, define the solution result as the characteristic root, and convert the characteristic equation into an approximate characteristic equation by selecting a specific characteristic root and inputting it into the feedback transfer function; The torque definition module is used to define the result with the same phase as the speed offset as the damping torque and define the result with the same phase as the angle offset as the synchronization torque based on the approximate analysis of the approximate characteristic equation.

10. The grid-type converter parameter simulation and analysis system according to claim 9, characterized in that: The formula of the approximate characteristic equation is: Where H is the synchronization coefficient; D is the damping coefficient; s is the complex frequency domain variable; H D (jω0) is the imaginary part of the feedback transfer function; j is the imaginary unit; ω0 is the rated angular frequency of the system.

11. The grid-type converter parameter simulation and analysis system according to claim 8, characterized in that: The derivation and transformation module includes: a relational module, a linearization module and a solution derivation module, wherein: The relational expression module is used to establish a damping torque equation of a grid-type converter containing a complete control loop based on a sixth-order synchronous machine model, and to generate a converter voltage-current relational expression according to a dynamic equation of the grid-type converter; The linearization module is used to linearize the voltage-current relationship of the converter at the equilibrium point to obtain a dq axis current array, and linearize the grid connection point voltage to obtain a dq axis voltage array; The solution derivation module is used to combine the dq axis current array and the dq axis voltage array and then insert them into the damping torque equation, and derive the dq axis impedance of the grid-type converter by solving the equation.

12. The grid-type converter parameter simulation and analysis system according to claim 11, characterized in that: The formula of the converter voltage-current relationship is: Where, ω0 is the rated angular frequency of the system; L f is the filter inductor; C f is the filter capacitor; U td is the d-axis component of the grid-connected point voltage; U tq is the q-axis component of the grid-connected point voltage; I d I is the current inner loop d-axis control current; q E is the current inner loop q axis control current; d PI is the PWM control d-axis command value; cc (s) is the current inner loop PI control link; PI vc (s) is the voltage outer loop PI control link; f VF It is the voltage feedforward filter link.

13. The grid-connected converter parameter simulation and analysis system according to claim 11, characterized in that: The damping torque equation is: Where, ΔT GFM is the damping torque of the grid-type converter; ΔP is the electromagnetic power; U t is the grid voltage amplitude; Z GFMd (s) is the d-axis impedance of the grid-type converter; Z GFMq (s) is the q-axis impedance of the grid-type converter; Δδ is the angle change of the damping torque; u td0 is the steady-state value of the grid-connected point voltage d-axis; Δu d is the change in the voltage d-axis component; Δu q is the change in the voltage q-axis component; Δi d is the change in the d-axis component of the current; Δi q is the change in the q-axis component of the current.

14. The grid-connected converter parameter simulation and analysis system according to claim 8, characterized in that: The simulation analysis module includes: a software simulation module and a numerical evaluation module, wherein: The software simulation module is used to simulate the damping characteristics of the grid-type converter containing a complete control loop using simulation software, and generate a Bode diagram showing the damping characteristics of the grid-type converter; The numerical evaluation module is used to set initial complex frequency domain variables, input them into the characteristic equation of the damping torque model, obtain the corresponding damping torque vector by adjusting the outer loop bandwidth, and adjust the value of the outer loop bandwidth in turn to measure the matrix dominant eigenvalue of the power grid system. According to the numerical change trend of the matrix dominant eigenvalue, the influence of the numerical change of the outer loop bandwidth on the damping torque is evaluated.

15. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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