Kinetic grey box modal analysis method, device, equipment, medium and product of following net type inverter

Abstract

The invention discloses a dynamic grey box modal analysis method, device and equipment for a following grid type inverter, a medium and a product, and relates to the field of dynamic stability of a power system. The method comprises the following steps: based on an admittance splitting theory, splitting the dynamics of the following grid type inverter, then determining the overall admittance when the following grid type inverter is aligned to a global coordinate system, further determining a disturbance quantity, and determining an overall participation factor based on the disturbance quantity; performing normalization conversion on the overall participation factors based on participation comparison, and then positioning a leading controller; calculating an explicit parameter participation factor based on the dominant controller and the overall admittance, and determining the parameter sensitivity; parameter sensitivity is used to improve the stability of the power system. The method aims to reasonably analyze the influence degree of different controllers in the following grid type inverter on the stability so as to position the key control loop and the key control parameters influencing the power system, so that the control parameters of the following grid type inverter are effectively set and optimized, and the system stability is improved.

Description

Technical Field

[0001] The present application relates to the field of dynamic stability of power systems, and in particular to a method, device, equipment, medium and product for dynamic gray box modal analysis of a grid-following inverter. Background Art

[0002] The large-scale access of grid-following inverters (GFL) has profoundly changed the dynamic characteristics of the power system, and the unstable oscillation caused by the interaction of GFL with the power grid has attracted widespread attention. The oscillation problem of traditional synchronous generators has been fully studied in the past. The various oscillation stability problems of grid-connected systems including grid-following inverters are more complicated. Power electronic equipment often requires complex control loops to achieve multiple control objectives, so it presents complex dynamic characteristics. In addition, since multiple control loops are often strongly coupled, the control parameters are difficult to adjust, and oscillation problems dominated by different control loops may occur in practice.

[0003] Modal analysis based on the state-space model (MASS) has attracted much attention due to its use of linear algebra to evaluate system stability and response characteristics. MASS quantifies the contribution of each state variable to a specific mode through participation factors (PF), which helps to identify key influencing factors and potential improvement measures for the system. MASS requires complete control details of the system, however, inverter-based resources (IBRs) are often only provided with gray box or even black box models.

[0004] The impedance model concentrates the dynamic characteristics of all components on the voltage and current ports of the components, and analyzes the stability of the system through the dynamic matrix of the whole system. On this basis, modal analysis based on the impedance model (MAI) is used to analyze and evaluate the contribution of system components to the system oscillation mode from the component level. MAI focuses on treating IBRs as a whole, so it cannot locate the main causes affecting the system dynamics to the control loop and state variables like MASS. The idea of ​​splitting the control algorithm of the inverter into several discrete circuit elements provides the possibility of deepening the modal analysis method into the internal links of IBRs, but this still requires further feasibility analysis. Summary of the invention

[0005] The purpose of this application is to provide a method, device, equipment, medium and product for dynamic gray box modal analysis of a grid-following inverter, which can make a reasonable analysis of the degree of influence of different controllers in the grid-following inverter on stability, so as to locate the key control loops and key control parameters that affect the power system, thereby effectively adjusting and optimizing the control parameters of the grid-following inverter to improve system stability.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, the present application provides a method for dynamic gray box modal analysis of a grid-connected inverter, comprising:

[0008] For any busbar-connected grid-following inverter in the power system, the overall admittance when aligned to the global coordinate system is determined based on split dynamics; the split dynamics is obtained by splitting the dynamics of the grid-following inverter based on the admittance splitting theory; the split dynamics include: electromagnetic dynamics dominated by the current control loop and synchronous dynamics dominated by the phase-locked loop; the overall admittance includes the first part of the admittance, the second part of the admittance and the third part of the admittance that characterize the electromagnetic dynamics and the synchronous dynamics; wherein the first part of the admittance and the third part of the admittance are respectively related to the current control loop and the phase-locked loop parameters, while the second part of the admittance is affected by the coupling of the two control loop parameters of the current control loop and the phase-locked loop;

[0009] For any grid-following inverter connected to a busbar in the power system, a disturbance amount is determined according to the overall admittance, and an overall participation factor is determined based on the disturbance amount; the overall participation factor includes a participation factor characterizing the degree of participation of electromagnetic dynamics and a participation factor characterizing the degree of participation of synchronous dynamics; the participation factor characterizing the degree of participation of electromagnetic dynamics is caused by the first part of the admittance and the second part of the admittance, while the participation factor characterizing the degree of participation of synchronous dynamics is caused by the second part of the admittance and the third part of the admittance;

[0010] For any grid-following inverter connected to a busbar in the power system, the overall participation factor is normalized and converted based on the participation ratio, and the leading controller is located according to the calculated participation ratio value; the leading controller is a controller that plays a leading role in the stability of the power system;

[0011] For any grid-following inverter connected to a bus in the power system, explicit parameter participation factors are calculated based on the dominant controller and the overall admittance to determine parameter sensitivity to improve the stability of the power system; the parameter sensitivity characterizes the influence of the sensitivity of the parameters in the overall admittance on the dominant eigenvalue of the power system dynamics.

[0012] Optionally, the expression of the overall admittance is:

[0013]

[0014] Among them, Y mDQ is the overall admittance; The angle deviation matrix determined for the initial power flow; Y medq is the overall admittance of electromagnetic dynamics in the current control loop; K mU is the coefficient matrix related to the steady-state voltage; K mI is the coefficient matrix related to the steady-state current; U mPLL is the equivalent voltage caused by the phase-locked loop parameters; is the angle deviation matrix determined for the initial power flow Perform inverse operation; Y meDQ The first part of the admittance for characterizing electromagnetic dynamics and synchronous dynamics; Y mDQ1 The second part of the admittance characterizing electromagnetic dynamics and synchronous dynamics; Y mDQ2 The third part of the admittance characterizes electromagnetic dynamics and synchronous dynamics.

[0015] Optionally, the expression of the disturbance amount is:

[0016]

[0017] Among them, ΔY mDQ is the overall admittance Y mDQ The disturbance amount; ΔY meDQ The first part of the admittance Y for characterizing electromagnetic dynamics and synchronous dynamics meDQ The disturbance amount; ΔY msDQ1 The second part of the admittance Y for the characterization of electromagnetic dynamics and synchronous dynamics msDQ1 The disturbance amount; ΔY msDQ2 The third part of the admittance Y characterizing electromagnetic dynamics and synchronous dynamics msDQ2 The disturbance amount; ΔY medq is the overall admittance Y of the electromagnetic dynamics in the current control loop medg The disturbance amount; E2 is the second-order unit matrix; ΔK mU is the coefficient matrix K related to the steady-state voltage mU The disturbance amount; ΔK mI is the coefficient matrix K related to the steady-state current mI The disturbance amount; ε me and ε ms are both scalar quantities representing the degree of disturbance.

[0018] Optionally, the overall participation factor is expressed as:

[0019]

[0020]

[0021] Among them, PF me PF is the participation factor that characterizes the degree of participation in electromagnetic dynamics; ms is the participation factor that characterizes the degree of participation in synchronous dynamics; <, > is the Frobenius inner product; λ k is the kth eigenvalue of the power system; is the element Z of the dynamic node impedance matrix of the whole power system mm In λ k Take the residue at; * is to take the conjugate transpose of the matrix; Y meDQ (λ k ) is in λ k The first partial admittance at msDQ1 (λ k ) is in λ k The second part of the admittance at msDQ2 (λ k ) is in λ k The third part of the admittance at .

[0022] Optionally, the participation ratio is calculated as:

[0023]

[0024] Among them, PR me is the participation ratio based on EMAI to characterize electromagnetic dynamics; PR ms is the participation ratio based on EMAI to characterize synchronous dynamics; PF me is the participation factor based on EMAI to characterize the degree of participation in electromagnetic dynamics; PF ms is the participation factor based on EMAI to characterize the degree of participation in synchronous dynamics; m is the serial number of the bus in the power system; PR me′ is the participation ratio based on MASS to characterize electromagnetic dynamics; PR ms′ is the participation ratio based on MASS to characterize synchronous dynamics; PF me′ is the participation factor based on MASS to characterize the degree of participation in electromagnetic dynamics; PF ms′ is the participation factor based on MASS to characterize the degree of participation in synchronous dynamics; PF mid is the participation factor of the integral link of the d-axis PI controller of the current control loop; PF miq is the participation factor of the integral link of the q-axis PI controller of the current control loop; PF mθ is the participation factor of the angle variable of the phase-locked loop; PF mω is the participation factor of the PI integral controller in the phase-locked loop.

[0025] Optionally, the expression corresponding to the parameter sensitivity of the PI controller in the current control loop is:

[0026]

[0027] in, is the parameter sensitivity of the proportional gain of the PI controller; is the parameter sensitivity of the integral gain of the PI controller; s is the Laplace operator; G del is the control delay transfer function; Z medq is the impedance of electromagnetic dynamics in the current control loop; K pi is the proportional gain of the PI controller; K ii is the integral gain of the PI controller;

[0028] Parameter sensitivity in the phase-locked loop and the equivalent voltage U caused by the phase-locked loop parameters mPLL Related; U mPLL Determined by measurement.

[0029] In a second aspect, the present application provides a gray box modal analysis device for a grid-following inverter, comprising:

[0030] The overall admittance determination module is used to determine the overall admittance of a grid-following inverter connected to any busbar in the power system when aligned to the global coordinate system based on split dynamics; the split dynamics is obtained by splitting the dynamics of the grid-following inverter based on the admittance splitting theory; the split dynamics include: electromagnetic dynamics dominated by the current control loop and synchronous dynamics dominated by the phase-locked loop; the overall admittance includes a first part of the admittance, a second part of the admittance and a third part of the admittance that characterize the electromagnetic dynamics and the synchronous dynamics; wherein the first part of the admittance and the third part of the admittance are respectively related to the current control loop and the phase-locked loop parameters, while the second part of the admittance is affected by the coupling of the two control loop parameters of the current control loop and the phase-locked loop;

[0031] An overall participation factor determination module is used for determining a disturbance amount according to the overall admittance for a grid-following inverter connected to any busbar in the power system, and determining an overall participation factor based on the disturbance amount; the overall participation factor includes a participation factor characterizing the degree of participation of electromagnetic dynamics and a participation factor characterizing the degree of participation of synchronous dynamics; the participation factor characterizing the degree of participation of electromagnetic dynamics is caused by the first part of the admittance and the second part of the admittance, while the participation factor characterizing the degree of participation of synchronous dynamics is caused by the second part of the admittance and the third part of the admittance;

[0032] A participation ratio calculation module is used to normalize and convert the overall participation factor of any grid-connected inverter connected to a busbar in the power system based on the participation ratio, and locate the leading controller according to the calculated participation ratio value; the leading controller is the controller that plays a leading role in the stability of the power system;

[0033] A parameter sensitivity determination module is used to calculate the explicit parameter participation factor of any bus-connected grid-following inverter in the power system based on the dominant controller and the overall admittance, and determine the parameter sensitivity to improve the stability of the power system; the parameter sensitivity characterizes the influence of the sensitivity of the parameter in the overall admittance on the dominant characteristic value of the power system dynamics.

[0034] In a third aspect, the present application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned gray box modal analysis method for dynamics of a grid-following inverter.

[0035] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned gray-box modal analysis method for dynamics of a grid-connected inverter.

[0036] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above-mentioned grid-following inverter dynamic gray box modal analysis method.

[0037] According to the specific embodiments provided in this application, this application has the following technical effects:

[0038] The present application provides a method, device, equipment, medium and product for the dynamic gray box modal analysis of a grid-following inverter. Based on the admittance splitting theory, the dynamics of the grid-following inverter are split, and then the overall admittance when aligned to the global coordinate system is determined, and then the disturbance amount is determined, and the overall participation factor is determined based on the disturbance amount; the overall participation factor is normalized and converted based on the participation ratio, and then the dominant controller is located; the explicit parameter participation factor is calculated based on the dominant controller and the overall admittance to determine the parameter sensitivity; the parameter sensitivity is used to improve the stability of the power system. The present application makes a reasonable analysis of the degree of influence of different controllers on stability in the grid-following inverter to locate the key control loops and key control parameters that affect the power system, thereby effectively adjusting and optimizing the control parameters of the grid-following inverter to improve the system stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1The flowchart of the gray box modal analysis method for the grid-following inverter dynamics;

[0041] Figure 2 This is the topology diagram of the grid-following inverter;

[0042] Figure 3 is the equivalent circuit diagram of the grid-following inverter control element; where: Figure 3 (a) is the equivalent circuit diagram of dq sequence control; Figure 3 (b) is the equivalent circuit diagram of positive and negative sequence control; Figure 3 (c) is a schematic diagram of the equivalent circuit of the control element;

[0043] Figure 4 This is a demonstration diagram of synchronous dynamics; Figure 4 (a) is a schematic diagram of coordinate system transformation; Figure 4 (b) is a schematic diagram of synchronous dynamics embedded admittance;

[0044] Figure 5 Schematic diagram of busbar system for transformation 14;

[0045] Figure 6 It is a simulation waveform diagram of GFL8 with active load step fault of bus 8;

[0046] Figure 7 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0049] Modal analysis based on the state-space model (MASS) requires the system to be a white box model, so it is not suitable for scenarios where grid-forming inverters (GFL) can only be provided with gray box or even black box models. The technical problem to be solved by this application is to perform gray box participation evaluation on the dynamics dominated by different controllers inside the grid-forming inverter. Specifically: Based on the idea of ​​admittance splitting, the dynamics of the grid-forming inverter are divided into electromagnetic dynamics (ED) dominated by the current control loop (CCL) and synchronous dynamics SD (SD) dominated by the phase-locked loop (PLL). The overall PF characterizing ED and SD is proposed to evaluate the degree of participation of different control loops, and the analytical parameter PF is proposed to improve unstable oscillation modes. The gray box modal analysis of the internal dynamics of the grid-forming inverter is realized. The purpose of this application is to quickly locate the controller inside the grid-following inverter that plays a dominant role in system stability, and to propose a gray box modal analysis method for the internal dynamics of the grid-following inverter.

[0050] In an exemplary embodiment, Figure 1 As shown, a method for dynamic gray box modal analysis of a grid-connected inverter is provided. The method is executed by a computer device, and can be executed by a computer device such as a terminal or a server alone, or by a terminal and a server together. In the embodiment of the present application, the server to which the method is applied is used as an example for explanation, and includes the following steps.

[0051] like Figure 1 As shown, the gray box modal analysis method for the grid-following inverter provided in this application includes:

[0052] Step 100: For any busbar-connected grid-type inverter in the power system, determine the overall admittance when aligned to the global coordinate system based on split dynamics. Split dynamics is obtained by splitting the dynamics of the grid-type inverter based on the admittance splitting theory; the split dynamics include: electromagnetic dynamics dominated by the current control loop and synchronous dynamics dominated by the phase-locked loop. The overall admittance includes the first part of the admittance, the second part of the admittance, and the third part of the admittance that characterize the electromagnetic dynamics and the synchronous dynamics; wherein the first part of the admittance and the third part of the admittance are respectively related to the current control loop and the phase-locked loop parameters, while the second part of the admittance is affected by the coupling of the two control loop parameters of the current control loop and the phase-locked loop.

[0053] Step 200: For any grid-following inverter connected to a busbar in the power system, a disturbance amount is determined according to the overall admittance, and an overall participation factor is determined based on the disturbance amount. The overall participation factor includes a participation factor characterizing the degree of participation of electromagnetic dynamics and a participation factor characterizing the degree of participation of synchronous dynamics; the participation factor characterizing the degree of participation of electromagnetic dynamics is caused by the first part of the admittance and the second part of the admittance, while the participation factor characterizing the degree of participation of synchronous dynamics is caused by the second part of the admittance and the third part of the admittance.

[0054] Step 300: For any grid-connected inverter connected to a bus in the power system, the overall participation factor is normalized and converted based on the participation ratio, and the leading controller is located according to the calculated participation ratio value. The leading controller is the controller that plays a leading role in the stability of the power system.

[0055] Step 400: For any busbar-connected grid-following inverter in the power system, an explicit parameter participation factor is calculated based on the dominant controller and the overall admittance to determine the parameter sensitivity to improve the stability of the power system. The parameter sensitivity characterizes the influence of the sensitivity of the parameter in the overall admittance on the dominant characteristic value of the power system dynamics.

[0056] The expression of overall admittance is:

[0057]

[0058] Among them, Y mDQ is the overall admittance; The angle deviation matrix determined for the initial power flow; Y medq is the overall admittance of electromagnetic dynamics in the current control loop; K mU is the coefficient matrix related to the steady-state voltage; K mI is the coefficient matrix related to the steady-state current; U mPLL is the equivalent voltage caused by the phase-locked loop parameters; is the angle deviation matrix determined for the initial power flow Perform inverse operation; Y meDQ The first part of the admittance for characterizing electromagnetic dynamics and synchronous dynamics; Y msDQ1 The second part of the admittance characterizing electromagnetic dynamics and synchronous dynamics; Y msDQ2 The third part of the admittance characterizes electromagnetic dynamics and synchronous dynamics.

[0059] The expression of the disturbance is:

[0060]

[0061] Among them, ΔY mDQ is the overall admittance Y mDQ The disturbance amount; ΔYmeDQ The first part of the admittance Y for characterizing electromagnetic dynamics and synchronous dynamics meDQ The disturbance amount; ΔY msDQ1 The second part of the admittance Y for the characterization of electromagnetic dynamics and synchronous dynamics msDQ1 The disturbance amount; ΔY msDQ2 The third part of the admittance Y characterizing electromagnetic dynamics and synchronous dynamics msDQ2 The disturbance amount; ΔY medq is the overall admittance Y of the electromagnetic dynamics in the current control loop medq The disturbance amount; E2 is the second-order unit matrix; ΔK mU is the coefficient matrix K related to the steady-state voltage mU The disturbance amount; ΔK mI is the coefficient matrix K related to the steady-state current mI The disturbance amount; ε me and ε ms are both scalar quantities representing the degree of disturbance.

[0062] The expression of the overall participation factor is:

[0063]

[0064]

[0065] Among them, PF me PF is the participation factor that characterizes the degree of participation in electromagnetic dynamics; ms is the participation factor that characterizes the degree of participation in synchronous dynamics; <, > is the Frobenius inner product; λ k is the kth eigenvalue of the power system; is the element Z of the dynamic node impedance matrix of the whole power system mm In λ k Take the residue at; * is to take the conjugate transpose of the matrix; Y meDQ (λ k ) is in λ k The first partial admittance at msDQ1 (λ k ) is in λ k The second part of the admittance at msDQ2 (λ k ) is in λ k The third part of the admittance at .

[0066] The calculation formula for the participation ratio is:

[0067]

[0068] Among them, PR me is the participation ratio based on EMAI to characterize electromagnetic dynamics; PR msis the participation ratio based on EMAI to characterize synchronous dynamics; PF me is the participation factor based on EMAI to characterize the degree of participation in electromagnetic dynamics; PF ms is the participation factor based on EMAI to characterize the degree of participation in synchronous dynamics; m is the serial number of the bus in the power system; PR me′ is the participation ratio based on MASS to characterize electromagnetic dynamics; PR ms′ is the participation ratio based on MASS to characterize synchronous dynamics; PF me′ is the participation factor based on MASS to characterize the degree of participation in electromagnetic dynamics; PF ms′ is the participation factor based on MASS to characterize the degree of participation in synchronous dynamics; PF mid is the participation factor of the integral link of the d-axis PI controller of the current control loop; PF miq is the participation factor of the integral link of the q-axis PI controller of the current control loop; PF mθ is the participation factor of the angle variable of the phase-locked loop; PF mω is the participation factor of the PI integral controller in the phase-locked loop.

[0069] The expression corresponding to the parameter sensitivity of the PI controller in the current control loop is:

[0070]

[0071] in, is the parameter sensitivity of the proportional gain of the PI controller; is the parameter sensitivity of the integral gain of the PI controller; s is the Laplace operator; G del is the control delay transfer function; Z medq is the impedance of electromagnetic dynamics in the current control loop; K pi is the proportional gain of the PI controller; K ii is the integral gain of the PI controller.

[0072] Parameter sensitivity in the phase-locked loop and the equivalent voltage U caused by the phase-locked loop parameters mPLL Related; U mPLL Determined by measurement.

[0073] The technical solution of the present application includes the admittance splitting of the grid-type inverter, calculating the overall participation factor of the dynamics characterized by different controllers of the grid-type converter, locating the controller of the grid-type converter that plays a leading role in the system stability, and calculating the explicit parameter participation factor to enhance the system damping and improve the system stability. The steps of the solution are as follows, and the following steps are performed in sequence:

[0074] Step 1: Admittance splitting of grid-connected inverter.

[0075] Based on the idea of ​​admittance splitting, the dynamics of the grid-following converter are divided into electromagnetic dynamics (ED) dominated by the current control loop (CCL) and synchronous dynamics (SD) dominated by the phase-locked loop (PLL).

[0076] The m in all variable subscripts corresponds to the GFL connected to the mth busbar in the system. m Related. Figure 4 (a) b is the angular velocity of the system reference power supply, θ m ,θ m0 and Δθ m It is GFL m Angle, steady-state angle, and angle deviation relative to the reference supply. When the PLL does not provide additional dynamics, i.e., Δθ m =0, which indicates Figure 4 (a) The swing coordinate system and the stable coordinate system coincide. At this time, the overall admittance of the ED in the CCL is expressed as Y medq Here we focus on the overall admittance Y when considering PLL mDQ The splitting process.

[0077] The small signal transfer function of PLL is shown in equation (1).

[0078]

[0079] Where K mpP , K miP and H mv Respectively represent GFL m The PLL proportional gain, integral gain and voltage-to-angle transfer function. md , ΔU mq and ΔU mdq Respectively represent GFL m d-axis voltage, q-axis voltage and dq-axis voltage. s is the Laplace operator.

[0080] The voltage variable is transformed from the dq axis of the swing coordinate system to the DQ axis of the global coordinate system:

[0081]

[0082] Among them U m0 、u mq0 、u md0 and Tθ m0 They represent the initial voltage value, the initial voltage value of the q-axis, the initial voltage value of the d-axis, and the angle deviation matrix determined by the initial power flow.mD , Δu mQ and Δu mDQ Respectively represent GFL m The D-axis voltage, Q-axis voltage and DQ-axis voltage.

[0083] The current also satisfies a similar relationship to equation (2). Figure 4 (b) and formula (3) give GFL m Admittance Y when aligned to the global coordinate system mDQ Transformation diagram and expression.

[0084]

[0085] Among them, E2 and I m0 denote the second-order unit matrix and the initial value of the current respectively. The superscript -1 denotes the inverse operation.

[0086] H mv U m0 is a scalar. For (E2+U m0 H mv ) -1 Using the matrix inversion lemma, we can convert Y mDQ Split into three parts of admittance Y representing ED and SD in formula (4) meDQ , Y msDQ1 and Y msDQ2 .Y meDQ and Y msDQ2 Each is related to CCL and PLL parameters, and Y msDQ1 Affected by the coupling of two control loop parameters.

[0087]

[0088] Where K mU and K mI are the coefficient matrices related to steady-state voltage and current, respectively. mPLL Indicates the equivalent voltage caused by the PLL parameters.

[0089]

[0090] U mPLL =u md0 +s 2 / (K miP +sK mpP )

[0091] where i mq0 and i md0 are the initial values ​​of q-axis and d-axis currents respectively.

[0092] The initial values ​​of voltage and current are shown in equation (6).

[0093] u md0 =U m ,u mq0 =0,i md0 =P m / U m ,i mq0 =-Q m / U m (6)

[0094] Among them U m , P m and Q m GFL m Voltage amplitude, output active power and reactive power.

[0095] Y meDQ , Y msDQ1 and Y msDQ2 They can be obtained by measuring and fitting. Cut off the PLL control link, that is, set the PLL gain to 0. mDQ It can be divided into Y meDQ and Y msDQ1 +Y msDQ2 .Y msDQ1 +Y msDQ2 Only U mPLL is the variable to be determined, and only K miP and K mpP Unknown. mU and K mI There are two non-zero values, so we can write two equations at a suitable frequency point to solve K miP and K mpP . So far Y mDQ It is then split into three parts in formula (4).

[0096] Step 2: Calculate the overall participation factor of the dynamics characterized by different controllers of the grid-type converter.

[0097] Evaluating GFL m The overall PF of the overall participation level is defined as PF m .

[0098]

[0099] in, is the element Z of the dynamic node impedance matrix of the whole power system mm In λ k Take the residue at; * is the conjugate transpose of the matrix. <,> is the Frobenius inner product. λ k is the kth eigenvalue of the power system. k and ΔY mDQ Respectively represent λ kand Y mDQ The disturbance amount. m It represents ΔY mDQ A scalar indicating the degree of disturbance.

[0100] Taking the disturbance value of formula (4) we can get:

[0101]

[0102] where ε me and ε ms are scalars of the degree of disturbance; they represent ΔY meDQ and Δ(1 / U mPLL ) degree of disturbance.

[0103] In order to further locate the main loop affecting the system, GFL is defined by analogy with formula (9): m PF characterizing the degree of involvement of ED and SD me and PF ms .

[0104]

[0105] PF me By Y meDQ and Y msDQ1 Commonly caused by PF ms By Y msDQ1 and Y msDQ2 This also reflects that Y msDQ1 It is affected by the coupling of two control loop parameters. me and PF ms They reflect the characteristics of CCL and PLL respectively.

[0106] Step 3: Locate the controller of the grid-type converter that plays a leading role in system stability.

[0107] Based on MASS, the state variables PF of all GFLs are calculated.

[0108] PF mid PF miq PF mθ and PF mω Respectively represent GFL m The PF of the integral link of the dq axis PI controller of the CCL, the PF of the angle variable of the PLL, and the PF of the PI integral link controller in the PLL. In order to normalize the PF of the EMAI and MASS methods, the participation ratio (PR) is defined to evaluate the ED and SD participation of different GFLs.

[0109]

[0110] Where || means taking the absolute value. The subscript ' means characterizing the ED and SD characteristics from the state variables. PR me and PR me’ denotes the PR of ED from EMAI and MASS respectively, and PR ms and PR ms’ Indicates the PR of SD from EMAI and MASS respectively. According to the PR of ED and SD characteristics of different grid-type converters in the system me and PR ms The value of is used to locate the dominant controller corresponding to the key dynamics affecting the system stability. The factors affecting the system stability are narrowed down to specific controllers, so as to further optimize the control parameters of the key controllers to effectively improve the system stability.

[0111] Step 4: Calculate explicit parameter participation factors to enhance system damping and improve system stability.

[0112] In addition, we can also use the sensitivity of the admittance to a certain parameter ρ Localize the dominant causes affecting system dynamics to parameters.

[0113] The parameter PF is defined as (11), however Difficult to parse.

[0114]

[0115] Based on the results of admittance splitting, different parameter sensitivities are given The analysis result of .

[0116] First consider the parameters of ED. mDQ It can be expressed as:

[0117]

[0118] The solution to convert the admittance perturbation into an impedance perturbation.

[0119]

[0120] Depend on Figure 3 The equivalent result of the impedance splitting of CCL in is directly obtained

[0121] Equation (14) gives the parameter sensitivity of the proportional and integral gains of the PI controller in CCL.

[0122]

[0123] Among them G del =e -1.5Tsrepresents the control delay transfer function, and T represents the sampling period.

[0124] The sensitivity of the relevant parameters of the PLL is only related to the scalar U in equation (15). mPLL Related. mPLL It can be calculated directly through measurement.

[0125]

[0126] So far, the dominant cause affecting the system dynamics has been located in the parameters.

[0127] The key controller, i.e., the numerical value PF of each control parameter participation factor in the dominant controller, indicates the direction in which the dominant eigenvalue of the system will change when the corresponding control parameter is increased. The decrease in the real part of the system eigenvalue indicates an increase in the system damping, so the control parameter with the largest absolute value of the real part of the adjustment parameter participation factor PF is selected. If the real part of the PF value is positive, the corresponding control parameter value is reduced, and vice versa, if the real part of the PF value is negative, the corresponding control parameter value is increased. This achieves the purpose of increasing the system damping and improving the system stability.

[0128] This application effectively identifies the root cause of the influence of different controllers inside the grid-following inverter on system stability by performing admittance splitting on the grid-following inverter and then proposing an equivalent overall participation factor to evaluate the participation of electromagnetic dynamics dominated by different current controllers and synchronous dynamics dominated by phase-locked loops. The theoretical analysis is verified by numerical calculation and simulation results. The research results have certain guiding significance for the gray box modal analysis of the internal dynamics of the current grid-following inverter.

[0129] The overall topology of the grid-following inverter and filter inductor is as follows: Figure 2 shown. Figure 2 In the figure, PWM stands for inverter switch modulation, and abc-dq stands for Parker transformation. The equivalent circuit of the current loop control element of the grid-type inverter is as follows: Figure 3 (a). Where K pi , K ii , R iv , X iv 、F v , L f and G del =e -1.5Ts They are the proportional and integral gains of the PI controller, virtual resistance and inductance, voltage feedforward gain, filter inductance and control delay. The variables are converted from dq sequence to positive and negative sequence to facilitate decoupling from the control structure and simplify analysis, such as Figure 3 (b) is shown. The final equivalent current element of the control element is as follows Figure 3(c). Each control element and its equivalent circuit element have been marked with different colors, and the specific expression of the equivalent circuit element is given in equation (2). The m in all variable subscripts is the GFL connected to the mth bus in the system. m The PLL does not provide additional dynamics, which indicates that Figure 4 (a) The swing coordinate system and the stable coordinate system are aligned, that is, Δθ m = 0. All power admittances need to be aligned to the global coordinate system before analysis. Figure 4 (a) b is the angular velocity of the system reference power supply, θ m ,θ m0 and Δθ m It is GFL m Angle, steady-state angle, and angular deviation relative to a reference supply. Figure 4 (b) Schematic diagram of synchronous dynamics embedded admittance.

[0130] analyze Figure 5 Transformation of 14-bus system. Bus 1 is infinite bus. Buses 2, 3, 6 and 8 are connected to GFLs. The control parameters of all GFLs are the same. The proportional and integral gains of the PI controller in PLL are 62.83 and 986.96 respectively. The proportional and integral gains of the PI controller in CCL are 0.18 and 84.82 respectively. The filter impedance is 0.01+j0.03p.u.. The voltage feedforward and virtual impedance are set to 0. There is a weakly damped mode 2π(-1.04+j18.41) in the system. Due to the weak grid instability of the GFLs and GFL8 is the farthest from the infinite bus, it may mean that GFL8 has the greatest impact on this mode.

[0131] The participation evaluation results of EMAI and MASS are shown in Table 1. The 2nd and 4th columns are the ED participation evaluation of the two methods, and the 3rd and 5th columns are the SD participation evaluation of the two methods. The evaluation results of the two methods are very close, which effectively shows that EMAI can achieve the same evaluation effect as MASS.

[0132] Table 1 Participation evaluation results of two modal analysis methods

[0133]

[0134] From Table 1, we can see that GFL8 is the dominant component affecting system stability, while PF meThe highest value indicates that the ED of GFL8 plays a dominant role, so the CCL parameters need to be re-adjusted to improve system stability. According to the analysis, the parameter PF of the CLL proportional gain and integral gain of GFL8 is -68.56-j18.37 and -0.125+j0.601. From the real part of the parameter PF, it can be seen that increasing the CCL proportional gain is the most effective measure to increase the damping of this mode, and this will also reduce the oscillation frequency of this mode. When the CCL proportional gain is increased to 0.3, the mode becomes 2π(-2.32+j18.11). A 0.1pu active load step fault is set on bus 8 before and after parameter adjustment. The simulation results are as follows Figure 6 As shown, the peak value of the oscillation waveform is reduced after the parameter adjustment, which shows the effectiveness of the improvement measures.

[0135] The method mentioned in this application takes into account the influence of the interaction between different controllers inside the grid-following inverter, and effectively solves the problem of gray box participation evaluation of the dominant dynamics of different controllers inside the grid-following inverter. This method is suitable for power systems with a high proportion of grid-following inverters, and can effectively improve the stability of the system based on the explicit participation sensitivity factors in different controllers of the grid-following inverter. The proposed method is simple to calculate and has good practical engineering application value. It can quickly and conveniently evaluate the root causes of the internal grid-following inverter that affect the stability of the system.

[0136] Based on the same inventive concept, the embodiment of the present application also provides a grid-type inverter dynamic gray box modal analysis device for implementing the above-mentioned grid-type inverter dynamic gray box modal analysis method. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above-mentioned method, so the specific limitations in one or more embodiments of the grid-type inverter dynamic gray box modal analysis device provided below can refer to the limitations of the grid-type inverter dynamic gray box modal analysis method in the above text, and will not be repeated here.

[0137] In an exemplary embodiment, a grid-following inverter dynamic gray box modal analysis device is provided, comprising:

[0138] The overall admittance determination module is used to determine the overall admittance of a grid-following inverter connected to any bus in the power system when aligned to the global coordinate system based on split dynamics; the split dynamics is obtained by splitting the dynamics of the grid-following inverter based on the admittance splitting theory; the split dynamics include: electromagnetic dynamics dominated by the current control loop and synchronous dynamics dominated by the phase-locked loop; the overall admittance includes the first part of the admittance, the second part of the admittance and the third part of the admittance that characterize the electromagnetic dynamics and the synchronous dynamics; wherein the first part of the admittance and the third part of the admittance are respectively related to the current control loop and the phase-locked loop parameters, while the second part of the admittance is affected by the coupling of the two control loop parameters of the current control loop and the phase-locked loop.

[0139] The overall participation factor determination module is used to determine the disturbance amount according to the overall admittance of a grid-following inverter connected to any bus in the power system, and determine the overall participation factor based on the disturbance amount; the overall participation factor includes a participation factor characterizing the degree of participation of electromagnetic dynamics and a participation factor characterizing the degree of participation of synchronous dynamics; the participation factor characterizing the degree of participation of electromagnetic dynamics is caused by the first part of the admittance and the second part of the admittance, while the participation factor characterizing the degree of participation of synchronous dynamics is caused by the second part of the admittance and the third part of the admittance.

[0140] The participation ratio calculation module is used to normalize and convert the overall participation factor of the grid-following inverter connected to any bus in the power system based on the participation ratio, and locate the dominant controller according to the calculated participation ratio value; the dominant controller is the controller that plays a leading role in the stability of the power system.

[0141] The parameter sensitivity determination module is used to calculate the explicit parameter participation factor of any bus-connected grid-following inverter in the power system based on the dominant controller and the overall admittance, and determine the parameter sensitivity to improve the stability of the power system; the parameter sensitivity characterizes the influence of the sensitivity of the parameters in the overall admittance on the dominant characteristic value of the power system dynamics.

[0142] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 7 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. 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 for the dynamic gray box modal analysis data of the grid-type inverter. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication 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, a method for dynamic gray box modal analysis of a grid-type inverter is implemented.

[0143] Those skilled in the art will understand that Figure 7The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application 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. In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0144] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0145] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0146] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0147] Those of ordinary skill 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 the memory, database or other medium used in the embodiments provided in the present application 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, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0148] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0149] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0150] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A gray box modal analysis method for grid-following inverter dynamics, characterized in that: The grid-following inverter dynamics gray box modal analysis method comprises: For any busbar-connected grid-following inverter in the power system, the overall admittance when aligned to the global coordinate system is determined based on split dynamics; the split dynamics is obtained by splitting the dynamics of the grid-following inverter based on the admittance splitting theory; the split dynamics include: electromagnetic dynamics dominated by the current control loop and synchronous dynamics dominated by the phase-locked loop; the overall admittance includes the first part of the admittance, the second part of the admittance and the third part of the admittance that characterize the electromagnetic dynamics and the synchronous dynamics; wherein the first part of the admittance and the third part of the admittance are respectively related to the current control loop and the phase-locked loop parameters, while the second part of the admittance is affected by the coupling of the two control loop parameters of the current control loop and the phase-locked loop; For any grid-following inverter connected to a busbar in the power system, a disturbance amount is determined according to the overall admittance, and an overall participation factor is determined based on the disturbance amount; the overall participation factor includes a participation factor characterizing the degree of participation of electromagnetic dynamics and a participation factor characterizing the degree of participation of synchronous dynamics; the participation factor characterizing the degree of participation of electromagnetic dynamics is caused by the first part of the admittance and the second part of the admittance, while the participation factor characterizing the degree of participation of synchronous dynamics is caused by the second part of the admittance and the third part of the admittance; For any grid-following inverter connected to a busbar in the power system, the overall participation factor is normalized and converted based on the participation ratio, and the leading controller is located according to the calculated participation ratio value; the leading controller is a controller that plays a leading role in the stability of the power system; For any grid-following inverter connected to a bus in the power system, explicit parameter participation factors are calculated based on the dominant controller and the overall admittance to determine parameter sensitivity to improve the stability of the power system; the parameter sensitivity characterizes the influence of the sensitivity of the parameters in the overall admittance on the dominant eigenvalue of the power system dynamics.

2. The method for dynamic gray box modal analysis of a grid-connected inverter according to claim 1, characterized in that: The expression of the overall admittance is: Among them, Y mDQ is the overall admittance; The angle deviation matrix determined for the initial power flow; Y medq is the overall admittance of electromagnetic dynamics in the current control loop; K mU is the coefficient matrix related to the steady-state voltage; K mI is the coefficient matrix related to the steady-state current; U mPLL is the equivalent voltage caused by the phase-locked loop parameters; is the angle deviation matrix determined for the initial power flow Perform inverse operation; Y meDQ The first part of the admittance for characterizing electromagnetic dynamics and synchronous dynamics; Y msDQ1 The second part of the admittance characterizing electromagnetic dynamics and synchronous dynamics; Y msDQ2 The third part of the admittance characterizes electromagnetic dynamics and synchronous dynamics.

3. The method for dynamic gray box modal analysis of a grid-connected inverter according to claim 2, characterized in that: The expression of the disturbance is: Among them, ΔY mDQ is the overall admittance Y mDQ The disturbance amount; ΔY meDQ The first part of the admittance Y for characterizing electromagnetic dynamics and synchronous dynamics meDQ The disturbance amount; ΔY msDQ1 The second part of the admittance Y for the characterization of electromagnetic dynamics and synchronous dynamics msDQ1 The disturbance amount; ΔY msDQ2 The third part of the admittance Y characterizing electromagnetic dynamics and synchronous dynamics msDQ2 The disturbance amount; ΔY medq is the overall admittance Y of the electromagnetic dynamics in the current control loop medq The disturbance amount; E2 is the second-order unit matrix; ΔK mU is the coefficient matrix K related to the steady-state voltage mU The disturbance amount; ΔK mI is the coefficient matrix K related to the steady-state current mI The disturbance amount; ε me and ε ms are both scalar quantities representing the degree of disturbance.

4. The method for dynamic gray box modal analysis of a grid-connected inverter according to claim 1, characterized in that: The expression of the overall participation factor is: Among them, PF me PF is the participation factor that characterizes the degree of participation in electromagnetic dynamics; ms is the participation factor that characterizes the degree of participation in synchronous dynamics; <,> is the Frobenius inner product; λ k is the kth eigenvalue of the power system; is the element Z of the dynamic node impedance matrix of the whole power system mm In λ k Take the residue at; * is to take the conjugate transpose of the matrix; Y meDQ (λ k ) is in λ k The first partial admittance at msDQ1 (λ k ) is in λ k The second part of the admittance at msDQ2 (λ k ) is in λ k The third part of the admittance at .

5. The method for dynamic gray box modal analysis of a grid-connected inverter according to claim 1, characterized in that: The calculation formula for the participation ratio is: |PF me' |=|PF mid |+|PF miq | |PF ms' |=|PF mθ |+|PF mω | Among them, PR me is the participation ratio based on EMAI to characterize electromagnetic dynamics; PR ms is the participation ratio based on EMAI to characterize synchronous dynamics; PF me is the participation factor based on EMAI to characterize the degree of participation in electromagnetic dynamics; PF ms is the participation factor based on EMAI to characterize the degree of participation in synchronous dynamics; m is the serial number of the bus in the power system; PP me , is the participation ratio based on MASS to characterize electromagnetic dynamics; PR ms , is the participation ratio based on MASS to characterize synchronous dynamics; PF me , is the participation factor based on MASS to characterize the degree of participation in electromagnetic dynamics; PF ms , is the participation factor based on MASS to characterize the degree of participation in synchronous dynamics; PR mid is the participation factor of the integral link of the d-axis PI controller of the current control loop; PF miq is the participation factor of the integral link of the q-axis PI controller of the current control loop; PF mθ is the participation factor of the angle variable of the phase-locked loop; PF mω is the participation factor of the PI integral controller in the phase-locked loop.

6. The method for dynamic gray box modal analysis of a grid-connected inverter according to claim 1, characterized in that: The expression corresponding to the parameter sensitivity of the PI controller in the current control loop is: in, is the parameter sensitivity of the proportional gain of the PI controller; is the parameter sensitivity of the integral gain of the PI controller; s is the Laplace operator; G del is the control delay transfer function; Z medq is the impedance of electromagnetic dynamics in the current control loop; K pi is the proportional gain of the PI controller; K ii is the integral gain of the PI controller; Parameter sensitivity in the phase-locked loop and the equivalent voltage U caused by the phase-locked loop parameters mPLL Related; U mPLL Determined by measurement.

7. A gray box modal analysis device for a grid-following inverter, characterized in that: The grid-following inverter dynamic gray box modal analysis device comprises: The overall admittance determination module is used to determine the overall admittance of a grid-following inverter connected to any busbar in the power system when aligned to the global coordinate system based on split dynamics; the split dynamics is obtained by splitting the dynamics of the grid-following inverter based on the admittance splitting theory; the split dynamics include: electromagnetic dynamics dominated by the current control loop and synchronous dynamics dominated by the phase-locked loop; the overall admittance includes a first part of the admittance, a second part of the admittance and a third part of the admittance that characterize the electromagnetic dynamics and the synchronous dynamics; wherein the first part of the admittance and the third part of the admittance are respectively related to the current control loop and the phase-locked loop parameters, while the second part of the admittance is affected by the coupling of the two control loop parameters of the current control loop and the phase-locked loop; An overall participation factor determination module is used for determining a disturbance amount according to the overall admittance for a grid-following inverter connected to any busbar in the power system, and determining an overall participation factor based on the disturbance amount; the overall participation factor includes a participation factor characterizing the degree of participation of electromagnetic dynamics and a participation factor characterizing the degree of participation of synchronous dynamics; the participation factor characterizing the degree of participation of electromagnetic dynamics is caused by the first part of the admittance and the second part of the admittance, while the participation factor characterizing the degree of participation of synchronous dynamics is caused by the second part of the admittance and the third part of the admittance; A participation ratio calculation module is used to normalize and convert the overall participation factor of any grid-connected inverter connected to a busbar in the power system based on the participation ratio, and locate the leading controller according to the calculated participation ratio value; the leading controller is the controller that plays a leading role in the stability of the power system; A parameter sensitivity determination module is used to calculate the explicit parameter participation factor of any bus-connected grid-following inverter in the power system based on the dominant controller and the overall admittance, and determine the parameter sensitivity to improve the stability of the power system; the parameter sensitivity characterizes the influence of the sensitivity of the parameter in the overall admittance on the dominant characteristic value of the power system dynamics.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the gray box modal analysis method for a grid-following inverter according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the gray box modal analysis method for dynamics of a grid-connected inverter described in any one of claims 1 to 6 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the gray box modal analysis method for dynamics of a grid-connected inverter described in any one of claims 1 to 6 is implemented.

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