A new energy power generation system stability evaluation method, device, medium and equipment

Abstract

This application discloses a method, apparatus, medium, and equipment for stability assessment of a new energy power generation system. The method includes: obtaining inverter parameters corresponding to the component parameters of different components in the new energy power generation system; determining the intersection frequency when the amplitude of the inverter parallel impedance is equal to the amplitude of the grid impedance, based on the inverter parameters and the output impedance expressions of each inverter, using the inverter parallel impedance expression and the grid impedance expression; determining the corresponding system phase margin based on each intersection frequency; plotting the relationship curve between component parameters and system phase margin based on the correspondence between the component parameters of different components and the inverter parameters; determining the target system phase margin corresponding to the target component parameters based on the relationship curve; and performing a stability assessment of the new energy power generation system based on the target system phase margin to obtain the assessment result. This application can quickly and accurately assess the stability of a new energy power generation system.

Description

Technical Field

[0001] This invention relates to the field of power grid operation safety technology, and in particular to a method for evaluating the stability of a new energy power generation system. Background Technology

[0002] With the popularization of new energy power generation, the installed capacity of new energy sources such as photovoltaics and wind power has achieved leapfrog growth. Currently, the stability analysis of new energy power generation systems mainly relies on impedance analysis.

[0003] However, when new energy power generation systems experience equipment switching or parameter changes, the amplitude-frequency and phase-frequency characteristics of the inverter-side parallel impedance will change. Impedance analysis methods need to be repeatedly performed, requiring the redrawing of the Bode plot of the inverter's parallel impedance and the grid impedance to recalculate the system's phase margin and thus determine its stability. Therefore, existing methods for assessing the stability of new energy power generation systems are extremely cumbersome, have low feasibility, and poor adaptability to equipment switching and parameter changes. They cannot quickly and accurately assess the stability of the power generation system in situations involving equipment switching and parameter changes. Summary of the Invention

[0004] In view of this, the present invention provides a method for evaluating the stability of a new energy power generation system, the main purpose of which is to solve the problem of not being able to quickly and accurately evaluate the stability of a new energy power generation system under parameter fluctuations and equipment switching conditions.

[0005] To address the above problems, this application provides a method for stability assessment of a new energy power generation system, characterized by comprising: Obtain the inverter parameters corresponding to the parameters of each component in the new energy power generation system; Based on the parameters of each inverter and the output impedance expression of each inverter, the intersection frequency when the amplitude of the inverter parallel impedance is equal to the amplitude of the grid impedance is determined by using the expression of the inverter parallel impedance and the expression of the grid impedance. Based on the frequency of each intersection point, determine the system phase margin corresponding to each intersection point frequency; Based on the correspondence between the parameters of different components and the inverter parameters, plot the relationship curves between the component parameters and the system phase margin corresponding to each component. Based on the relationship curve, the target system phase margin corresponding to the target component parameters is determined, and the stability of the new energy power generation system is evaluated based on the target system phase margin to obtain the evaluation result.

[0006] Optionally, determining the system phase margin corresponding to each intersection frequency specifically includes: The phase difference is determined based on the frequency of each intersection point; Based on each phase difference, the phase margin of each system is determined.

[0007] Optionally, the n The expression for the parallel impedance of inverters in a parallel inverter system is:

[0008] No. t The output impedance expression for the inverter is:

[0009] in, Z op ( s () represents the parallel impedance of the inverter; n Indicates the number of inverters in the system; L 1 represents the inverter-side filter inductor; C Indicates the filter capacitor. L 2. Mains-side filter inductor; s Represented as the Laplace operator; K pwm The transfer function representing the modulation signal to the inverter bridge output voltage; G d ( s ) is the equivalent transfer function for digital control delay; H 1 represents the capacitor current feedback coefficient; H 2 represents the grid-connected current feedback coefficient; G i ( s ) represents the current regulator function; G f Represents the grid voltage feedforward coefficient; G v ( s ) indicates a parallel impedance reshaping feedforward circuit.

[0010] Optionally, the expression for the grid impedance includes: Z g ( s )= sL g in, Z g ( s () represents the power grid impedance; s Represented as the Laplace operator; L g This represents the equivalent inductance value of the power grid.

[0011] To address the aforementioned problems, this application provides a stability assessment device for a new energy power generation system, comprising: The acquisition module is used to acquire the inverter parameters corresponding to the parameters of each component in the new energy power generation system. The first determining module is used to determine the intersection frequency when the amplitude of the inverter parallel impedance is equal to the amplitude of the grid impedance, based on the parameters of each inverter and the output impedance expression of each inverter, using the parallel impedance expression of the inverter and the grid impedance expression. The second determining module is used to determine the system phase margin corresponding to each intersection frequency based on the intersection frequency. The plotting module is used to plot the relationship curves between the parameters of each component and the inverter parameters, based on the correspondence between the parameters of different components and the inverter parameters. The evaluation module is used to determine the target system phase margin corresponding to the target component parameters of the target component based on the relationship curve, and to perform a stability evaluation on the new energy power generation system based on the target system phase margin to obtain the evaluation result.

[0012] Optionally, the second determining module is specifically used for: The phase difference is determined based on the frequency of each intersection point; Based on each phase difference, the phase margin of each system is determined.

[0013] To address the aforementioned problems, this application provides a storage medium storing a computer program that, when executed by a processor, implements the steps of any of the above-described methods for evaluating the stability of a new energy power generation system.

[0014] To address the aforementioned problems, this application provides an electronic device, comprising at least a memory and a processor, wherein the memory stores a computer program, and the processor, when executing the computer program in the memory, implements the steps of any of the above-described methods for evaluating the stability of a new energy power generation system.

[0015] The stability assessment method for new energy power generation systems in this application obtains the corresponding inverter parameters for various components by pre-adjusting their parameters. Since fluctuations in the parameters of certain components can alter the output impedance characteristics of a single unit, thereby affecting the characteristics of the inverter's parallel impedance, and consequently the amplitude intersection point of the inverter's parallel impedance and the grid impedance, a new system phase margin can be generated. Therefore, the phase margin corresponding to the fluctuations in each inverter parameter can be pre-calculated by combining the correspondence between the parameters of different components and the inverter parameters. Then, by linearly representing the trend of component parameter fluctuations and phase margin changes, the phase margin curve of the system as a function of a certain component parameter can be obtained, i.e., the relationship curve between the component parameter and the phase margin. Accordingly, when the number of system devices changes due to the switching on of new energy units, the relationship between the fluctuations in a certain type of component parameter and the system phase margin under different inverter parameters can still be obtained by referring to the above process. Based on this, the relationship between the specific component parameters and the phase margin can be directly found based on the component parameters of the target component, thereby enabling the rapid and accurate determination of the system phase margin. This, in turn, allows for a rapid and accurate assessment of the stability of the new energy power generation system, improving assessment efficiency.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a flowchart illustrating a method for evaluating the stability of a new energy power generation system according to an embodiment of this application; Figure 2 This is a diagram of a single-phase grid-connected inverter and its control structure in an embodiment of this application; Figure 3(a) is a control block diagram of a single-phase grid-connected inverter; Figure 3(b) is a simplified control block diagram of a single-phase LCL grid-connected inverter; Figure 4 This is a Norton equivalent model diagram of a single-phase grid-connected inverter in the embodiments of this application; Figure 5 Virtual resistor in the embodiments of this application R The relationship curve between the system phase margin (PM) and the phase margin (PM). Figure 6 This is a structural block diagram of a new energy power generation system stability assessment device according to another embodiment of this application; Figure 7 This is a structural block diagram of an electronic device according to another embodiment of this application. Detailed Implementation

[0018] Various embodiments and features of this application are described herein with reference to the accompanying drawings.

[0019] It should be understood that various modifications can be made to the embodiments described herein. Therefore, the above description should not be considered as limiting, but merely as an example of embodiments. Other modifications within the scope and spirit of this application will be apparent to those skilled in the art.

[0020] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.

[0021] These and other features of this application will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.

[0022] It should also be understood that although this application has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this application.

[0023] The above and other aspects, features and advantages of this application will become more apparent when taken in conjunction with the accompanying drawings and in view of the following detailed description.

[0024] Specific embodiments of this application are described thereafter with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of this application, which can be implemented in various ways. Well-known and / or repeated functions and structures are not described in detail to avoid unnecessary or redundant details that could obscure the application. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely to serve as a representative basis for teaching those skilled in the art to use this application in a variety of substantially any suitable detailed structures.

[0025] This specification may use the phrases “in one embodiment,” “in another embodiment,” “in yet another embodiment,” or “in other embodiments,” all of which may refer to one or more of the same or different embodiments according to this application.

[0026] This application provides a method for stability assessment of a new energy power generation system, which can be specifically applied to a new energy power generation system with multiple inverters connected in parallel, such as... Figure 1 As shown, the method in this embodiment includes the following steps: Step S101: Obtain the inverter parameters corresponding to the parameters of each component in the new energy power generation system. In this step, the inverter parameters include: filter inductor, filter capacitor, DC-side voltage, triangular carrier amplitude, proportional coefficient of the current regulator, resonant coefficient of the current regulator, voltage feedforward coefficient, sampling period, grid equivalent inductance, capacitor current feedback coefficient, grid-connected current feedback coefficient, and grid voltage feedforward coefficient. The component parameters can be any hardware or control parameter from the inverter parameters, such as resistors.

[0027] Step S102: Based on the parameters of each inverter and the output impedance expression of each inverter, the intersection frequency when the amplitude of the inverter parallel impedance is equal to the amplitude of the grid impedance is determined by using the inverter parallel impedance expression and the grid impedance expression. In the specific implementation of this step, the above inverter parameters and grid parameters can be substituted into the inverter parallel impedance expression ( Z op ( s )) and the expression for grid impedance ( Z g ( s Define the function Amp = abs(abs( Z op )-abs( Z g Let Amp=0, and then solve for the frequency f at the intersection of the amplitudes of the two, that is, extract the frequency point f where the amplitude of the inverter parallel impedance is equal to the amplitude of the grid impedance.

[0028] Specifically, taking the component parameter resistance R For example, to improve the efficiency of solving "Amp=0", the `optimoptions('particleswarm')` function in Matlab can be used. Each calculation uses 50 particle swarm searches (i.e., `'SwarmSize', 50`) to quickly obtain the frequency `f`. In this embodiment, `OP1=optimoptions('particleswarm','SwarmSize',50,'PlotFcn','pswplotbestf')` is used to define the number of particle swarm optimizations for the particle swarm algorithm as 50. `pswplotbestf` is used to plot the current optimal objective function value with the number of iterations in real time, facilitating observation of algorithm convergence. Then, a `for` loop is used to select the parameters. R Define parameters as parameter variables. R The value range (10-200) and step size (2) are defined in each iteration cycle. RGiven a fixed value, the particleswarm function is used to find f that satisfies Amp=0 within the frequency range of 1~5000Hz. Each time... R After value iteration, the amplitude intersection frequency f can be obtained, and then... R Store it in set A, and you will get the result. R Given the value, Z g ( s )and Z op ( s The amplitude intersection frequency f of )

[0029] in, n The expression for the parallel impedance of inverters in a parallel inverter system is:

[0030] No. t The output impedance expression for the inverter is:

[0031] in, Z op ( s () represents the parallel impedance of the inverter; n Indicates the number of inverters in the system; L 1 represents the inverter-side filter inductor; C Indicates the filter capacitor. L 2. Mains-side filter inductor; s Represented as the Laplace operator; K pwm The transfer function representing the modulation signal to the inverter bridge output voltage; G d ( s ) is the equivalent transfer function for digital control delay; H 1 represents the capacitor current feedback coefficient; H 2 represents the grid-connected current feedback coefficient; G i ( s ) represents the current regulator function; G f Represents the grid voltage feedforward coefficient; G v ( s ) indicates a parallel impedance reshaping feedforward circuit.

[0032] The expression for grid impedance is: Z g ( s )= sL g in, Z g ( s () represents the power grid impedance; s Represented as the Laplace operator; L g This represents the equivalent inductance value of the power grid.

[0033] Step S103: Based on the frequency of each intersection point, determine the system phase margin corresponding to each intersection point frequency; In the specific implementation process, this step can be based on different... R Solve for the inverter parameters corresponding to the given values. Z op ( s )and Z g ( s The amplitude intersection frequency of ) is used to determine the frequency of each. Z op ( s )and Z g ( s The phase of the system is determined, and the phase margin of the system is determined.

[0034] Specifically, the angle function can be used to extract... Z g ( s )and Z op ( s The phase at frequency f is used to calculate the phase margin PM of the system, PM = angle( Z op )-angle( Z g +90°.

[0035] Step S104: Based on the correspondence between the parameters of different components and the inverter parameters, plot the relationship curves between the component parameters and the system phase margin corresponding to each component. In the specific implementation process of this step, after obtaining the phase margin of each sample, the fluctuation parameter (in this example, the virtual resistance value) can be plotted. R The curve shows the relationship between the sample phase margin and the horizontal axis.

[0036] Step S105: Based on the relationship curve, determine the target system phase margin corresponding to the target component parameters of the target component, and perform a stability assessment on the new energy power generation system based on the target system phase margin to obtain the assessment result.

[0037] In this step, after obtaining the relationship curve, the corresponding relationship curve can be found based on the target component parameters, thereby enabling quick and accurate determination of the corresponding target phase margin. When inverter equipment is switched on or off, the number of inverters of each type changes, i.e., the system combination changes. At this time, parameter fluctuations can still be handled by referring to the above process.

[0038] In this embodiment, parameters are preset during implementation. R The range of values ​​and step size. In each iteration cycle, i.e. R Given a fixed value, use the particleswarm function to find the frequency range of 1~5000Hz that satisfies Amp=abs(abs(Z)). op )-abs(Z g The sample frequency f when ))=0, where Z op ( s ) represents the parallel impedance of the inverter. Z g ( s () represents the grid impedance. Then, each... R The frequency f corresponding to the intersection of the amplitude values ​​is obtained, and the frequency f is then... R The value is stored in set A, thus obtaining the value. R Given the value, Z g ( s )and Z op ( s The sample frequency f at the amplitude intersection of the amplitudes is then used. Subsequently, the corresponding sample phase margin can be determined based on each sample frequency f. Specifically, the angle function can be used to extract the phase margin. Z g ( s )and Z op ( s The phase at frequency f is used to calculate the phase margin of the system, PM = angle(Z). op )-angle(Z g +90°. Finally, each R The phase margin PM at the frequency f where the amplitude crosses is obtained is stored in set B. Based on the mapping relationship between sets A and B, a plot can be drawn. R -PM continuous curve, that is, the relationship curve between the fluctuation of a certain parameter and the phase margin.

[0039] The method in this embodiment obtains the inverter parameters corresponding to the component parameters of different components by pre-adjusting the parameters. Since the fluctuation of the component parameters of a certain type of component can change the output impedance characteristics of a single unit, thereby affecting the characteristics of the inverter's parallel impedance, and thus affecting the amplitude intersection point of the inverter's parallel impedance and the grid impedance, and generating a new system phase margin, the phase margin curve of the system as a function of the component parameter can be obtained in advance by linearly representing the trend of component parameter fluctuation and phase margin change. That is, the relationship curve between the component parameter and the phase margin of that component can be obtained. Accordingly, when the number of system equipment changes due to the switching of new energy units, the relationship between the fluctuation of a certain type of component parameter and the system phase margin under different inverter parameters can still be obtained by referring to the above process. Based on this, the relationship between the specific component parameter and the phase margin can be directly found based on the component parameter value of the target component, thereby quickly and accurately determining the system phase margin, and thus quickly and accurately evaluating the stability of the new energy power generation system, improving the evaluation efficiency. Specifically, when PM is greater than 0°, the system is in a stable state, that is, at this time... R The value is valid; when PM equals 0°, the system is in a critical state; when PM is less than 0°, the system is in an unstable state, i.e., at this time... R Invalid value.

[0040] In the implementation of the above embodiments, the inverter parallel impedance needs to be solved based on the inverter control structure and block diagram equivalent transformation.

[0041] The expression for the parallel impedance of the inverter is: (1) No. t The expression for the output impedance of the inverter is: (2) The expression for grid impedance is: Z g ( s )= sL g (3) Taking a single-phase inverter as an example, the main circuit and control structure are as follows: Figure 2 As shown, the upper part is the power circuit, and the lower part is the control section. The main circuit consists of a DC source, a full-bridge circuit, and an LCL filter. v dc The DC bus voltage is used as the output inverter-side current after passing through the full-bridge circuit. i 1. i 1. After passing through the filter circuit, the output grid-connected current is... i 2. v pccThis is the voltage at the point of common coupling (PCC). The power grid consists of voltage sources. v g and equivalent inductance L g It is configured in series. To suppress the resonance introduced by the LCL filter, an active damping strategy with capacitor current feedback is usually adopted. H 1 represents the active damping coefficient of the capacitor current; H 2 represents the grid-connected current feedback coefficient; the phase information of the common coupling point is extracted by the phase-locked loop (PLL) and combined with the current setpoint to form the grid-connected current reference signal. The difference between the reference signal and the real-time sampled value of the actual grid-connected current is calculated and then sent to the current regulator. G i (s); simultaneously, active damping with capacitor current feedback H1 and voltage feedforward are introduced. G f and G v Output modulated wave v M Sinusoidal Pulse Width Modulation (SPWM) is employed.

[0042] according to Figure 2 The system control block diagram can be drawn, as shown in Figure 3(a). Based on the principle of equivalent transformation of control block diagrams, a simplified control block diagram of the single-phase LCL grid-connected inverter can be derived, as shown in Figure 3(b). Wherein, K... pwm G is the transfer function from the modulated signal to the inverter bridge output voltage, which is equal to the ratio of the DC-side voltage to the triangular carrier amplitude. d (s) is the equivalent transfer function of the digital control delay, which includes the calculation delay of one clock cycle and the modulation delay of half a clock cycle, and can be expressed as: (4) Among them, T s The sampling period.

[0043] To improve the fundamental gain and reduce the steady-state error of the grid-connected current, a quasi-PR regulator is adopted for the current regulator, and its transfer function expression is as follows: (5) in, K p This is the proportionality coefficient. K r The resonant coefficient; ω 0 represents the fundamental angular frequency; ω i For consideration The required resonant term bandwidth is 3dB, and the maximum allowable deviation of the grid frequency fluctuation is 0.5Hz. To ensure sufficient gain of the current regulator during grid frequency fluctuations, the following selection is made: ω i =πrad / s.

[0044] Based on the principle of equivalent transformation of control block diagrams, we can obtain the following in Figure 3(b): G x1 (s) and G x2 The expression for (s) is as follows: (6) In addition, a notch filter is used to suppress resonance. G notch (s) Extract the voltage harmonic signal from the PCC point voltage, and pass it through 1 / R ( R The virtual resistor is converted into a current signal and fed back to the inverter current setpoint. This causes the target inverter's current setpoint to be reduced by the harmonics in the grid-connected current. Consequently, the target inverter's output current contains harmonics with opposite phase to the harmonics in the total grid-connected current, thus achieving harmonic cancellation in the total grid-connected current and effectively suppressing system resonance. Therefore, G v The expression for (s) is as follows: (7) Where ζ is the damping coefficient. ω 0 represents the notch frequency of the notch filter. The notch filter in the feedforward stage needs to extract harmonic voltages other than the mains frequency for impedance reshaping; therefore, the notch frequency is set to 0. ω 0 is set as the fundamental angular frequency. Furthermore, considering the design method for the optimal second-order system, the following is selected: ζ =0.707.

[0045] Based on Figure 3(b), the Norton equivalent model of the grid-connected inverter system can be derived, as follows: Figure 4 As shown. Among them, i s (s) is the equivalent current source. . Z (s) represents the inverter output impedance. Z (s) and G o The expression for (s) is as follows (Z) t (s) is the first t (output impedance of the inverter) (8) (9) In other words, in this embodiment, formula (8) can be derived from the above formulas (4)-(7), which is to say, formula (2) is obtained. Subsequently, formulas (1), (2) and (3) can be used to solve for the frequency f when the amplitude of the inverter parallel impedance is equal to the amplitude of the grid impedance.

[0046] The following examples will be used to explain the methods described in this application.

[0047] The system consisting of inverter #1 and inverter #2 in Table 1 will be analyzed as an example. When the power generation system operates in a 1:1 configuration (i.e., two inverters connected in parallel, one inverter #1 and one inverter #2), by changing... R The value of is determined by using the inverter parallel impedance expression and the grid impedance expression to determine the frequency f when the inverter parallel impedance amplitude is equal to the grid impedance amplitude. Then, the phase difference is determined using the frequency f, and the phase margin is determined based on the phase difference. Thus, the combined 1:1 configuration can be obtained. R The phase margin variation of the power generation system under fluctuating operating conditions can be used to plot the resistance. R The relationship curve with phase stability margin, i.e. Figure 5 The solid line in the diagram represents the power generation system. When an additional inverter (#1) is added, the system becomes a 2:1 configuration (i.e., three inverters connected in parallel: two #1 inverters and one #2 inverter). This is achieved by changing... R The value of is determined by using the inverter parallel impedance expression and the grid impedance expression to determine the frequency f when the inverter parallel impedance amplitude is equal to the grid impedance amplitude. Then, the phase difference is determined using the frequency f, and the phase margin is determined based on the phase difference. Thus, the combination 2:1 can be obtained. R The phase margin of the system changes under fluctuating conditions, which can then be used to plot the parameters. R The relationship curve with phase stability margin, i.e. Figure 5 The dashed line in the middle.

[0048] Table 1:

[0049] In this embodiment, by pre-adjusting the component parameters of various components, the inverter parameters corresponding to the component parameters of different components can be obtained. Since the fluctuation of the component parameters of a certain type of component can change the output impedance characteristics of a single unit, thereby affecting the characteristics of the inverter's parallel impedance, and thus affecting the amplitude intersection point of the inverter's parallel impedance and the grid impedance, and generating a new system phase margin, the correspondence between the component parameters of different components and the inverter parameters can be combined. By solving for the phase margin corresponding to the fluctuation of each inverter parameter, and then using a linear representation of the trend of component parameter fluctuation and phase margin change, the phase margin curve of the system as a function of the parameter of a certain component can be obtained, that is, the relationship curve between the component parameter and the phase margin of that component can be obtained. Accordingly, when the number of system devices changes due to the switching of new energy units, the relationship between the fluctuation of a certain type of component parameter and the system phase margin under different inverter parameters can still be obtained by referring to the above process. Based on this, the relationship between the specific component parameters and the phase margin can be directly found based on the component parameters of the target component, thereby enabling the rapid and accurate determination of the system phase margin. This, in turn, allows for a rapid and accurate assessment of the stability of the new energy power generation system, improving assessment efficiency.

[0050] The method in this application can quickly solve for the stability margin of new energy power generation systems, enabling rapid calculation of the stability margin under conditions of new energy unit equipment switching and parameter fluctuations. It solves the problem of the complexity of existing methods for solving the stability margin of new energy power generation systems, and also addresses the issue that when new energy unit equipment experiences switching or parameter fluctuations, the system's stability margin fluctuates significantly, requiring a re-evaluation of the system's stability margin.

[0051] Another embodiment of this application provides a stability assessment device for a new energy power generation system, such as... Figure 6 As shown, it includes: The acquisition module 11 is used to acquire the inverter parameters corresponding to the parameters of each component in the new energy power generation system. The first determining module 12 is used to determine the intersection frequency when the amplitude of the inverter parallel impedance is equal to the amplitude of the grid impedance, based on the parameters of each inverter and the output impedance expression of each inverter, using the inverter parallel impedance expression and the grid impedance expression. The second determining module 13 is used to determine the system phase margin corresponding to each intersection frequency based on the intersection frequency; The plotting module 14 is used to plot the relationship curves between the parameters of each component and the inverter parameters, based on the correspondence between the parameters of different components and the inverter parameters. Evaluation module 15 is used to determine the target system phase margin corresponding to the target component parameters of the target component based on the relationship curve, and to perform a stability evaluation on the new energy power generation system based on the target system phase margin to obtain the evaluation result.

[0052] In this embodiment, the second determining module is specifically used for: Based on the frequency of each intersection point, the phase difference is determined; based on each phase difference, the phase margin of each system is determined.

[0053] In the specific implementation process of this embodiment, n The expression for the parallel impedance of inverters in a parallel inverter system is:

[0054] No. t The output impedance expression for the inverter is:

[0055] in, Z op ( s () represents the parallel impedance of the inverter; n Indicates the number of inverters in the system; L 1 represents the inverter-side filter inductor; C Indicates the filter capacitor. L 2. Mains-side filter inductor; s Represented as the Laplace operator; K pwm The transfer function representing the modulation signal to the inverter bridge output voltage; G d ( s ) is the equivalent transfer function for digital control delay; H 1 represents the capacitor current feedback coefficient; H 2 represents the grid-connected current feedback coefficient; G i ( s ) represents the current regulator function; G f Represents the grid voltage feedforward coefficient; G v ( s ) indicates a parallel impedance reshaping feedforward circuit.

[0056] In this embodiment, the expression for the power grid impedance is as follows: Z g ( s )= sL g in, Z g ( s () represents the power grid impedance; s Represented as the Laplace operator; L g This represents the equivalent inductance value of the power grid.

[0057] The device in this embodiment obtains the inverter parameters corresponding to the parameters of various components by pre-adjusting the component parameters of each component. Since fluctuations in the parameters of a certain type of component can change the output impedance characteristics of a single unit, thereby affecting the characteristics of the inverter's parallel impedance, and thus affecting the amplitude intersection point of the inverter's parallel impedance and the grid impedance, and generating a new system phase margin, the phase margin corresponding to the fluctuations of each inverter parameter can be calculated by combining the correspondence between the parameters of different components and the inverter parameters. Then, by linearly representing the trend of component parameter fluctuations and phase margin changes, the phase margin curve of the system as a function of the parameters of a certain component can be obtained, i.e., the relationship curve between the component parameters and the phase margin of that component can be obtained. Accordingly, when the number of system devices changes due to the switching of new energy units, the relationship between the fluctuations of a certain type of component parameters and the system phase margin under different inverter parameters can still be obtained by referring to the above process. Based on this, the relationship between the specific component parameters and the phase margin can be directly found based on the component parameters of the target component, thereby enabling the rapid and accurate determination of the system phase margin. This, in turn, allows for a rapid and accurate assessment of the stability of the new energy power generation system, improving assessment efficiency.

[0058] Another embodiment of this application provides a storage medium storing a computer program, which, when executed by a processor, implements the following method steps: Step 1: Obtain the inverter parameters corresponding to the parameters of each component in the new energy power generation system; Step 2: Based on the parameters of each inverter and the output impedance expression of each inverter, use the parallel impedance expression of the inverter and the grid impedance expression to determine the intersection frequency when the amplitude of the parallel impedance of the inverter is equal to the amplitude of the grid impedance. Step 3: Based on the frequencies at each intersection point, determine the system phase margin corresponding to each intersection point frequency; Step 4: Based on the correspondence between the parameters of different components and the inverter parameters, plot the relationship curves between the component parameters and the system phase margin for each component. Step 5: Based on the relationship curve, determine the target system phase margin corresponding to the target component parameters of the target component, and perform a stability assessment on the new energy power generation system based on the target system phase margin to obtain the assessment results.

[0059] The specific implementation process of the above method steps can be found in the embodiments of the above-mentioned new energy power generation system stability assessment method, which will not be repeated here.

[0060] In this application, the storage medium, by pre-adjusting the component parameters of various components, can obtain the inverter parameters corresponding to the component parameters of different components. Since the fluctuation of the component parameters of a certain type of component can change the output impedance characteristics of a single unit, thereby affecting the characteristics of the inverter's parallel impedance, and thus affecting the amplitude intersection point of the inverter's parallel impedance and the grid impedance, and generating a new system phase margin, the phase margin corresponding to the fluctuation of each inverter parameter can be calculated by combining the correspondence between the component parameters of different components and the inverter parameters. Then, by using a linear expression to represent the trend of component parameter fluctuation and phase margin change, the phase margin curve of the system as a function of the parameter of a certain component can be obtained, that is, the relationship curve between the component parameter and the phase margin of that component can be obtained. Accordingly, when the number of system devices changes due to the switching of new energy units, the relationship between the fluctuation of a certain type of component parameter and the system phase margin under different inverter parameters can still be obtained by referring to the above process. Based on this, the relationship between the specific component parameters and the phase margin can be directly found based on the component parameters of the target component, thereby enabling the rapid and accurate determination of the system phase margin. This, in turn, allows for a rapid and accurate assessment of the stability of the new energy power generation system, improving assessment efficiency.

[0061] Another embodiment of this application provides an electronic device, such as... Figure 7 As shown, it includes at least a memory 1 and a processor 2. The memory 1 stores a computer program, and the processor 2 performs the following method steps when executing the computer program in the memory 1: Step 1: Obtain the inverter parameters corresponding to the parameters of each component in the new energy power generation system; Step 2: Based on the parameters of each inverter and the output impedance expression of each inverter, use the parallel impedance expression of the inverter and the grid impedance expression to determine the intersection frequency when the amplitude of the parallel impedance of the inverter is equal to the amplitude of the grid impedance. Step 3: Based on the frequencies at each intersection point, determine the system phase margin corresponding to each intersection point frequency; Step 4: Based on the correspondence between the parameters of different components and the inverter parameters, plot the relationship curves between the component parameters and the system phase margin for each component. Step 5: Based on the relationship curve, determine the target system phase margin corresponding to the target component parameters of the target component, and perform a stability assessment on the new energy power generation system based on the target system phase margin to obtain the assessment results.

[0062] The specific implementation process of the above method steps can be found in the embodiments of the above-mentioned new energy power generation system stability assessment method, which will not be repeated here.

[0063] In this application, the storage medium allows for the prior adjustment of component parameters of various components, thereby obtaining the corresponding inverter parameters. Since fluctuations in the parameters of certain components can alter the output impedance characteristics of a single unit, they affect the characteristics of the inverter's parallel impedance, thus influencing the amplitude intersection point of the inverter's parallel impedance and the grid impedance, and generating a new system phase margin. Therefore, by combining the correspondence between the parameters of different components and the inverter parameters, the phase margin corresponding to the fluctuations in each inverter parameter can be calculated. Then, by linearly representing the trend of component parameter fluctuations and phase margin changes, the phase margin curve of the system as a function of a certain component parameter can be obtained, i.e., the relationship curve between the component parameter and the phase margin. Accordingly, when switching on new energy units causes changes in the number of system devices, the above process can still be used to obtain the relationship between the fluctuations of a certain type of component parameter and the system phase margin under different inverter parameters. Based on this, the relationship between the specific component parameters and the phase margin can be directly found based on the component parameters of the target component, thereby enabling the rapid and accurate determination of the system phase margin. This, in turn, allows for a rapid and accurate assessment of the stability of the new energy power generation system, improving assessment efficiency.

[0064] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. Those skilled in the art can make various modifications or equivalent substitutions to this application within the scope and nature of this application, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A method for evaluating the stability of a new energy power generation system, characterized in that, include: Obtain the inverter parameters corresponding to the parameters of each component in the new energy power generation system; Based on the parameters of each inverter and the output impedance expression of each inverter, the intersection frequency when the amplitude of the inverter parallel impedance is equal to the amplitude of the grid impedance is determined by using the expression of the inverter parallel impedance and the expression of the grid impedance. Based on the frequency of each intersection point, determine the system phase margin corresponding to each intersection point frequency; Based on the correspondence between the parameters of different components and the inverter parameters, plot the relationship curves between the component parameters and the system phase margin corresponding to each component. Based on the relationship curve, the target system phase margin corresponding to the target component parameters is determined, and the stability of the new energy power generation system is evaluated based on the target system phase margin to obtain the evaluation result.

2. The method as described in claim 1, characterized in that, The determination of the system phase margin corresponding to each intersection frequency specifically includes: The phase difference is determined based on the frequency of each intersection point; Based on each phase difference, the phase margin of each system is determined.

3. The method as described in claim 1, characterized in that, n The expression for the parallel impedance of inverters in a parallel inverter system is: No. t The output impedance expression for the inverter is: in, Z op ( s () represents the parallel impedance of the inverter; n Indicates the number of inverters in the system; L 1 represents the inverter-side filter inductor; C Indicates the filter capacitor. L 2. Mains-side filter inductor; s Represented as the Laplace operator; K pwm The transfer function representing the modulation signal to the inverter bridge output voltage; G d ( s ) is the equivalent transfer function for digital control delay; H 1 represents the capacitor current feedback coefficient; H 2 represents the grid-connected current feedback coefficient; G i ( s ) represents the current regulator function; G f Represents the grid voltage feedforward coefficient; G v ( s ) indicates a parallel impedance reshaping feedforward circuit.

4. The method as described in claim 1, characterized in that, The expression for the power grid impedance is: Z g ( s )= sL g in, Z g ( s () represents the power grid impedance; s Represented as the Laplace operator; L g This represents the equivalent inductance value of the power grid.

5. A stability assessment device for a new energy power generation system, characterized in that, include: The acquisition module is used to acquire the inverter parameters corresponding to the parameters of each component in the new energy power generation system. The first determining module is used to determine the intersection frequency when the amplitude of the inverter parallel impedance is equal to the amplitude of the grid impedance, based on the parameters of each inverter and the output impedance expression of each inverter, using the parallel impedance expression of the inverter and the grid impedance expression. The second determining module is used to determine the system phase margin corresponding to each intersection frequency based on the intersection frequency. The plotting module is used to plot the relationship curves between the parameters of each component and the inverter parameters, based on the correspondence between the parameters of different components and the inverter parameters. The evaluation module is used to determine the target system phase margin corresponding to the target component parameters of the target component based on the relationship curve, and to perform a stability evaluation on the new energy power generation system based on the target system phase margin to obtain the evaluation result.

6. The apparatus as claimed in claim 5, characterized in that, The second determining module is specifically used for: The phase difference is determined based on the frequency of each intersection point; Based on each phase difference, the phase margin of each system is determined.

7. A storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the steps of the stability assessment method for the new energy power generation system according to any one of claims 1-4.

8. An electronic device, characterized in that, It includes at least a memory and a processor, wherein the memory stores a computer program, and the processor, when executing the computer program in the memory, implements the steps of the stability assessment method for the new energy power generation system according to any one of claims 1-4.

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