Inverter multi-machine dynamic power angle stability analysis method, system, device and medium

Abstract

The application relates to the technical field of electrical engineering, and discloses an inverter multi-machine dynamic power angle stability analysis method, system, equipment and medium, which comprises the following steps: small signal modeling is performed on grid-following inverters and grid-forming inverters to obtain a frequency domain impedance model of a grid-following and grid-forming hybrid converter station; a power expression under a dynamic phasor method is constructed according to the frequency domain impedance model; a small signal coefficient equation under the dynamic phasor method is calculated based on a power transmission equation under the dynamic phasor method; the parameter frequency characteristics corresponding to the grid-following inverters and the grid-forming inverters are analyzed according to the small signal coefficient equation; and the parameter frequency characteristics are used to determine the inverter multi-machine dynamic power angle stability analysis result of the grid-following inverters and the grid-forming inverters. The application can realize accurate analysis of low-frequency power angle oscillation characteristics and stability of the hybrid inverter station.

Description

Technical Field

[0001] This invention relates to the field of electrical engineering technology, specifically to a method, system, equipment, and medium for dynamic power angle stability analysis of multiple inverters. Background Technology

[0002] With the increasing penetration rate of new energy power generation, represented by photovoltaics and wind power, the power system is exhibiting significant "weak grid" operation characteristics, namely, increased system equivalent impedance, reduced short-circuit capacity, and weakened grid strength. Against this backdrop, the dynamic interaction between grid-connected inverters and grid impedance is becoming increasingly complex, easily leading to new stability problems, particularly low-frequency oscillations. In traditional synchronous generator-dominated power systems, power angle stability analysis is based on the classic "second-order swing equation," which describes the dynamic relationship between rotor angular acceleration and the difference between mechanical and electromagnetic power. This relies on the synchronous generator's large rotational inertia and defined physical power angle. However, for new energy generators primarily using converter interfaces, they lack rotating mass and have relatively small inertia; therefore, traditional power transfer equations based on steady-state assumptions will produce significant errors. State-space methods for such oscillation problems analyze stability by establishing a global linearized model of the system and solving for eigenvalues. While providing complete modal information, the analysis is essentially limited to a specific linearized operating point, usually the fundamental frequency. When the system dynamics vary over a wide frequency band, a linearized model based on a single point cannot accurately capture all potential oscillation modes. Furthermore, some existing studies have neglected or simplified the dynamics of certain control components to simplify the models, resulting in inaccurate analyses of oscillation modes. Therefore, in-depth research on the inverter power angle stabilization mechanism dominated by voltage dynamics under weak grid conditions has significant theoretical and engineering value for ensuring the reliable operation of high-proportion renewable energy power systems.

[0003] The Chinese invention patent publication CN118739347B discloses a method and system for suppressing subsynchronous oscillations in a grid-connected / grid-connected hybrid parallel new energy system. This method reshapes the impedance of the hybrid parallel system by adding a damping compensation controller to the voltage control stage of the grid-connected inverter, thereby weakening its negative damping characteristics. However, its damping parameter design is complex, requiring the introduction of a strictly precise additional damping controller, which increases control complexity and cannot guarantee the robustness of the proposed control strategy under parameter perturbation. Therefore, improper parameter design may adversely affect oscillations in other frequency bands.

[0004] The frequency dynamic response optimization method based on grid-connected inverters disclosed in Chinese invention patent publication number CN117674183A, through a multi-parameter collaborative optimization control strategy considering different system damping ratios, can optimize the frequency fluctuation response characteristics of grid-connected virtual synchronous machine systems under different conditions of load fluctuation and active power command fluctuation. However, its parameter optimization method heavily relies on accurate acquisition of system state, making it difficult to guarantee control accuracy and robustness. Furthermore, this method is only applicable to grid-connected inverter power plants with a single control mode virtual synchronous machine, and is difficult to extend to grid-connected / grid-connected hybrid renewable energy power plants where system inertia is further reduced.

[0005] In summary, how to improve the accuracy of the analysis of low-frequency power angle oscillation characteristics and stability margin of hybrid inverter power plants has become an urgent problem to be solved. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to achieve accurate analysis of the low-frequency power angle oscillation characteristics and stability margin of hybrid inverter stations by constructing a unified broadband impedance model of the system.

[0007] The present invention solves the above-mentioned technical problems through the following technical means:

[0008] Small-signal modeling was performed on grid-connected inverters and grid-connected inverters to obtain the frequency domain impedance model of the grid-connected hybrid converter station. Construct a power expression under the dynamic phasor method based on the frequency domain impedance model; The small-signal coefficient equation under the dynamic phasor method is calculated based on the power transfer equation under the dynamic phasor method. Analyze the parameter frequency characteristics of the grid-connected inverter and the grid-connected inverter based on the small-signal coefficient equation. The frequency characteristics of the parameters are used to determine the dynamic power angle stability analysis results of the multi-machine inverter for the grid-connected inverter and the grid-connected inverter.

[0009] Optionally, the step of performing small-signal modeling on grid-connected inverters and grid-connected inverters to obtain the frequency domain impedance model of the grid-connected hybrid converter station includes: Obtain the grid-connected inverter and the grid-connected inverter corresponding to the grid-connected hybrid converter station structure diagram; Based on the above-mentioned grid-connected hybrid converter site structure diagram, calculate the dual closed-loop equivalent output impedance of the grid-connected converter, the impedance of the grid-connected inverter, and the negative impedance introduced by the phase-locked loop. The frequency domain impedance model of the grid-connected hybrid converter station is generated based on the dual closed-loop equivalent output impedance, the grid-connected inverter impedance, and the negative impedance.

[0010] Optionally, the calculation of the dual closed-loop equivalent output impedance of the grid-type converter, the impedance of the grid-type inverter, and the negative impedance introduced by the phase-locked loop based on the grid-connected hybrid converter site structure diagram includes: The dual closed-loop equivalent output impedance of the grid-connected converter, the grid-connected inverter impedance, and the negative impedance introduced by the phase-locked loop are calculated using the following formulas:

[0011]

[0012]

[0013] in, This represents the dual closed-loop equivalent output impedance of a grid-type converter. Indicates filter inductance, Indicates the filter capacitor. Represents the complex frequency variable of the Laplace transform. This represents the equivalent gain of the pulse width modulation stage. This indicates a PI regulator with grid-type current closed-loop control. This represents the integral adjustment coefficient of the phase-locked loop. This represents the proportional coefficient of the proportional inner loop control in a grid-type current proportional control system. This indicates the reference value for the grid current. This represents the small-signal transfer function of a phase-locked loop. Indicates the impedance of the grid-connected inverter. This represents the negative impedance introduced by the phase-locked loop.

[0014] Optionally, constructing the power expression under the dynamic phasor method based on the frequency domain impedance model includes: The equivalent line impedance is obtained by performing a star-delta transformation on the frequency domain impedance model. Based on the resistive and inductive portions of the equivalent line impedance, the power expression under the dynamic phasor method is derived.

[0015] Optionally, the step of performing a star-delta transformation on the frequency domain impedance model to obtain the equivalent line impedance includes: The equivalent line impedance is obtained by performing a star-delta transformation on the frequency domain impedance model using the following formula:

[0016]

[0017]

[0018] in, This represents the equivalent line impedance. This represents the dual closed-loop equivalent output impedance of a grid-type converter. Indicates the power grid impedance. Represents the complex frequency variable of the Laplace transform. Represents the imaginary unit. Indicates the rated power grid frequency. Indicates the inductance of the power grid. Represents equivalent line impedance The real part, Represents equivalent line impedance The imaginary part, Indicates the impedance of the grid-connected inverter. This indicates negative impedance.

[0019] Optionally, the calculation of the small-signal coefficient equation under the dynamic phasor method based on the power transfer equation under the dynamic phasor method includes: The small-signal coefficient equation is expressed as:

[0020] in, , , , They represent the small-signal coefficients, , Let these represent the active and reactive power transferred by the power source in the power transfer equation, respectively. Indicates the equivalent work angle. This indicates the magnitude of the electromotive force of the power source. Represents equivalent line impedance The real part, Represents equivalent line impedance The imaginary part.

[0021] Optionally, the step of analyzing the parameter frequency characteristics corresponding to the grid-connected inverter and the grid-connected inverter based on the small-signal coefficient equation includes: Construct a Bode plot for each small-signal coefficient in the small-signal coefficient equation; The frequency characteristics of the parameters are analyzed based on the Bode plot.

[0022] To address the aforementioned problems, this invention also proposes a multi-machine dynamic power angle stability analysis system for inverters, the system comprising: The frequency domain impedance model construction module is used to perform small-signal modeling on grid-connected inverters and grid-connected inverters to obtain the frequency domain impedance model of the grid-connected hybrid converter station. A power expression construction module is used to construct a power expression under the dynamic phasor method based on the frequency domain impedance model. The small-signal coefficient equation calculation module is used to calculate the small-signal coefficient equation under the dynamic phasor method based on the power transfer equation under the dynamic phasor method. The parameter frequency characteristic analysis module is used to analyze the parameter frequency characteristics of the grid-connected inverter and the grid-connected inverter based on the small-signal coefficient equation. The analysis result determination module is used to determine the multi-machine dynamic power angle stability analysis results of the grid-connected inverter and the grid-connected inverter based on the frequency characteristics of the parameters.

[0023] The present invention also provides a processing device, characterized in that it includes at least one processor and at least one memory communicatively connected to the processor, wherein: the memory stores program instructions executable by the processor, and the processor can execute the above-described method for multi-machine dynamic power angle stability analysis of inverters by calling the program instructions.

[0024] The present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores computer instructions, the computer instructions causing the computer to execute the above-described method for multi-machine dynamic power angle stability analysis of inverters.

[0025] The advantages of this invention are: This invention constructs a unified frequency domain impedance model to achieve equivalent modeling and analysis of the stability of the power angle oscillation frequency band of hybrid inverter plants, effectively reducing model complexity while ensuring analysis accuracy. Through power transfer equations and Bode plot analysis, it quantitatively characterizes the influence of capacity ratio, control parameters, etc. on system damping and oscillation, providing theoretical support and design basis for inverter parameter selection, hybrid inverter plant stability optimization, and reliable operation, and realizing accurate analysis of the low-frequency power angle oscillation characteristics and stability of hybrid inverter plants. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating a method for dynamic power angle stability analysis of multiple inverters in one embodiment of the present invention; Figure 2 This is a diagram of a grid-connected hybrid inverter power station structure, which combines grid-connected inverters and grid-connected inverters, according to one embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of a hybrid converter power station after star-delta transformation in one embodiment of the present invention; Figure 4 It is the voltage loop proportional regulation coefficient of the grid-type inverter in one embodiment of the present invention. A schematic diagram illustrating the changes; Figure 5 This is the voltage loop integral regulation coefficient of a grid-type inverter in one embodiment of the present invention. A schematic diagram illustrating the changes; Figure 6 This is the proportional adjustment coefficient of the current loop of the grid-connected inverter in one embodiment of the present invention. A schematic diagram illustrating the changes; Figure 7 This is the proportional adjustment coefficient of the current loop of the grid-connected inverter in one embodiment of the present invention. A schematic diagram illustrating the changes; Figure 8 This is a Bode plot of the small-signal coefficients as a function of the capacity of the grid-type converter in one embodiment of the present invention; Figure 9 This is a waveform diagram of the power step response of a grid-type structure in one embodiment of the present invention; Figure 10 This is a waveform diagram of the step response of the grid power structure when the given value of the d-axis current is changed in one embodiment of the present invention. Figure 11 This is a functional module diagram of a multi-machine dynamic power angle stability analysis system for inverters provided in one embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Reference Figure 1 The diagram shown is a flowchart illustrating a multi-machine dynamic power angle stability analysis method for inverters according to an embodiment of the present invention. In this embodiment, the multi-machine dynamic power angle stability analysis method for inverters includes: S1. Perform small-signal modeling on grid-connected inverters and grid-connected inverters to obtain the frequency domain impedance model of the grid-connected hybrid converter station.

[0029] In this embodiment of the invention, the grid-following inverter (GFL) is an inverter that passively follows the power grid, while the grid-forming inverter (GFM) is an inverter that actively builds the power grid and can autonomously establish voltage and frequency. This invention constructs an equivalent circuit diagram for a hybrid grid-following and grid-forming inverter power plant.

[0030] Specifically, the equal-frequency domain impedance model of the grid-connected hybrid converter power station simultaneously includes the dual closed-loop equivalent output impedance of the grid-connected converter. A grid-connected inverter can be equivalent to the grid-connected inverter impedance introduced by its current loop. With the negative impedance introduced by the phase-locked loop Parallel model.

[0031] Specifically, the step of performing small-signal modeling on grid-connected inverters and grid-connected inverters to obtain the frequency domain impedance model of the grid-connected hybrid converter station includes: Obtain the grid-connected inverter and the grid-connected inverter corresponding to the grid-connected hybrid converter station structure diagram; Based on the above-mentioned grid-connected hybrid converter site structure diagram, calculate the dual closed-loop equivalent output impedance of the grid-connected converter, the impedance of the grid-connected inverter, and the negative impedance introduced by the phase-locked loop. The frequency domain impedance model of the grid-connected hybrid converter station is generated based on the dual closed-loop equivalent output impedance, the grid-connected inverter impedance, and the negative impedance.

[0032] In this embodiment of the invention, the grid-connected hybrid converter plant structure diagram represents a converter plant structure diagram that combines grid-connected inverters and grid-connected inverters, specifically as follows: Figure 2 As shown, E is the output AC voltage of the grid-connected inverter, and Ug is the grid voltage. To determine the equivalent output impedance of a grid-connected converter with dual closed loops, a grid-connected inverter can be equivalently represented by the grid-connected inverter impedance introduced by its current loop. With the negative impedance introduced by the phase-locked loop Parallel connection model. Zg = Rg + jωLg is the grid impedance.

[0033] Specifically, the dual closed-loop equivalent output impedance of the grid-connected converter, the impedance of the grid-connected inverter, and the negative impedance introduced by the phase-locked loop are calculated using the following formulas:

[0034]

[0035]

[0036] in, This represents the dual closed-loop equivalent output impedance of a grid-type converter. Indicates filter inductance, Indicates the filter capacitor. Represents the complex frequency variable of the Laplace transform. This represents the equivalent gain of the pulse width modulation stage. This indicates a PI regulator with grid-type current closed-loop control. This represents the integral adjustment coefficient of the phase-locked loop. This represents the proportional coefficient of the proportional inner loop control in a grid-type current proportional control system. This indicates the reference value for the grid current. This represents the small-signal transfer function of a phase-locked loop. This indicates the impedance of the grid-connected inverter. This represents the negative impedance introduced by the phase-locked loop.

[0037] In this embodiment of the invention, the dual closed-loop equivalent output impedance of the grid-type converter, the impedance of the grid-connected inverter, and the negative impedance introduced by the phase-locked loop are combined to obtain the frequency domain impedance model of the grid-connected hybrid converter station. The parameters in the frequency domain impedance model can be reasonably set according to the relevant control parameters of the grid-connected inverter. Therefore, this invention can be applied to inverters with different parameters, improving the applicability of the dynamic power angle stability analysis results of multi-machine inverters.

[0038] This invention establishes a unified frequency domain impedance model that includes the control dynamics of grid-connected and grid-connected inverters, thereby achieving equivalent modeling and analysis of the stability of the power angle oscillation frequency band of hybrid inverter sites. This effectively reduces the complexity of the model while ensuring the accuracy of the analysis.

[0039] S2. Construct the power expression under the dynamic phasor method based on the frequency domain impedance model.

[0040] In this embodiment of the invention, the power expression represents the active and reactive power output expression of a standard power transmission circuit.

[0041] Specifically, the step of constructing the power expression under the dynamic phasor method based on the frequency domain impedance model includes: The equivalent line impedance is obtained by performing a star-delta transformation on the frequency domain impedance model. Based on the resistive and inductive portions of the equivalent line impedance, the power expression under the dynamic phasor method is derived.

[0042] In detail, for Figure 2 The grid-connected hybrid converter power station shown can be obtained by performing a star-delta transformation. Figure 3 , Figure 3 In The term, generated by the dynamic phasor method, represents the dynamic characteristics of the line, enabling subsequent frequency analysis to encompass the entire low-frequency band rather than a single frequency. After the star-delta transformation, the equivalent line impedance... It can be obtained using the formula for the star-triangle transformation.

[0043] Specifically, the equivalent line impedance is obtained by performing a star-delta transformation on the frequency domain impedance model using the following formula:

[0044]

[0045]

[0046] in, Indicates the equivalent line impedance. This represents the dual closed-loop equivalent output impedance of a grid-type converter. Indicates the power grid impedance. Represents the complex frequency variable of the Laplace transform. Represents the imaginary unit. Indicates the rated power grid frequency. Indicates the inductance of the power grid. Represents equivalent line impedance The real part, Represents equivalent line impedance The imaginary part, This indicates the impedance of the grid-connected inverter. This indicates negative impedance.

[0047] According to circuit theory, the impedance after transformation when directly connected in parallel with the two power sources can be ignored. The expressions for active and reactive power output of a standard power transfer circuit are:

[0048]

[0049] in, , These represent the active and reactive power transmitted by the power source, respectively. , This represents the resistance and inductance of the circuit transmission line. This indicates the magnitude of the electromotive force of the power source. This indicates the voltage magnitude on the power receiving side. It represents the phase difference (equivalent power angle) between the power supply and the power receiving side voltages. Indicates the rated power grid frequency.

[0050] In this embodiment of the invention, after obtaining the equivalent impedance of the entire hybrid system of the grid-connected inverter and the grid-connected inverter, the power transmission equation can be derived from the resistive and inductive parts of the equivalent circuit impedance through the above-mentioned active and reactive power output expressions of the standard transmission circuit.

[0051] This invention systematically reveals the intrinsic mechanism of low-frequency oscillation under mixed operation conditions of grid-connected and grid-connected inverters from the dual perspectives of impedance characteristics and power angle interaction, providing a theoretical basis for the configuration of control parameters and design specifications of multi-unit hybrid power plants.

[0052] S3. Calculate the small-signal coefficient equation under the dynamic phasor method based on the power transfer equation under the dynamic phasor method.

[0053] In this embodiment of the invention, the small-signal coefficient equation of the hybrid power station under the dynamic phasor method is the partial derivative of the output active power and reactive power with respect to the equivalent power angle and electromotive force. Specifically, during the operation of the grid-connected inverter... Very small, therefore , ,and The small-signal coefficient equation of the hybrid station under the dynamic phasor method is expressed as:

[0054] in, , , , They represent the small-signal coefficients, , Let these represent the active and reactive power transferred by the power source in the power transfer equation, respectively. Indicates the equivalent work angle. This indicates the magnitude of the electromotive force of the power source. Represents equivalent line impedance The real part, Represents equivalent line impedance The imaginary part.

[0055] S4. Analyze the parameter frequency characteristics of the grid-connected inverter and the grid-connected inverter based on the small-signal coefficient equation.

[0056] In this embodiment of the invention, the frequency characteristic represents the change in the low-frequency oscillation characteristics of the system when different control parameters change, and further provides guidance for the selection of control parameters for hybrid power station converters.

[0057] Specifically, the step of analyzing the parameter frequency characteristics of the grid-connected inverter and the grid-connected inverter based on the small-signal coefficient equation includes: Construct a Bode plot for each small-signal coefficient in the small-signal coefficient equation; The frequency characteristics of the parameters are analyzed based on the Bode plot.

[0058] In detail, each small-signal coefficient in the small-signal coefficient equation is an expression containing s in the complex frequency domain, and its frequency characteristics can be analyzed by plotting Bode plots in MATLAB.

[0059] S5. Determine the dynamic power angle stability analysis results of the inverter multi-machine of the grid-connected inverter and the grid-connected inverter based on the frequency characteristics of the parameters.

[0060] In this embodiment of the invention, the dynamic power angle stability analysis results of the multi-machine inverter represent the synchronization, oscillation characteristics, and overall system stability of the virtual power angles of each inverter in the hybrid system composed of the grid-connected inverter and the grid-connected inverter under different control parameters. Specifically, this can be determined by whether the power angle coupling between multiple machines and the power mutual feedback cause low-frequency oscillations / instability in the parameter frequency characteristics, as well as the changes in the power angle of each inverter over time (oscillation amplitude, frequency), oscillation mode, etc.

[0061] In detail, when different control parameters of the grid-connected / grid-connected converter are changed in the hybrid system, resonance peaks can be observed at different frequencies. The small-signal coefficients change when the control parameters of the grid-connected or grid-connected converter are altered. , , , The Bird diagram can be like Figure 4 , Figure 5 , Figure 6 , Figure 7 Specifically, such as Figure 4 As shown, this represents the voltage loop proportional regulation coefficient of the grid-connected inverter. The change in frequency and the resonance peak indicate that the system will oscillate at this frequency. Figure 5 This represents the voltage loop integral regulation coefficient of a grid-connected inverter. Changes, Figure 4 and Figure 5 Explanation of the adjustment coefficient of the network structure As the frequency increases, the low-frequency oscillations of the system gradually disappear and a 50Hz power frequency oscillation is generated. The low-frequency oscillation frequency gradually increases. Figure 6 , Figure 7 These represent the proportional adjustment coefficients of the current loop of the grid-connected inverter. Integral adjustment coefficient The changes. From Figure 6 , Figure 7 It can be seen that the grid-type control parameters have a relatively small impact on oscillation changes. This is because in hybrid systems, the grid type often plays a dominant role, while the grid-type inverter, which follows the PCC point voltage, usually has a relatively small impact on the entire system. Figure 8 This indicates that as the capacity of the grid-connected converter continues to increase, a significant resonance peak will appear, suggesting that connecting a large number of grid-connected converters will have an adverse effect on the low-frequency stability of the system.

[0062] To demonstrate the effectiveness of the dynamic power angle analysis method for this hybrid inverter power station, a hardware-in-the-loop experiment was conducted. The relevant electrical parameters for this experiment were set as follows: the d-axis command value for the grid-side current was: The q-axis command value for the grid-side current is: The inverter output frequency reference value is: The proportional and integral control coefficients of the phase-locked loop are 0.7 and 75, respectively; the active and reactive power droop coefficients are respectively: Line impedance The filter inductor and capacitor are as follows: By observing the active power step response waveform of the grid converter, the low-frequency dynamic power angle oscillation of the system can be analyzed.

[0063] Specifically, when the parameters of the grid-type or network-type control loop are changed, the power step response waveform of the network-type control loop is as follows: Figure 9 As shown, from Figure 9 As can be seen in (a), the hybrid system produces significant low-frequency oscillations during power surges, with an oscillation frequency of approximately 18 Hz. This is precisely the first hybrid system oscillation mode analyzed by the dynamic phasor method in this invention: low-frequency dynamic power angle oscillation. Furthermore, with the grid-type converter... As the power increases, the oscillations gradually disappear, which is consistent with the theoretical analysis. To further verify the correctness of the theory, experiments were conducted on the power step response when other control parameters changed, such as... Figure 9 As shown in (b), (c), and (d), these represent network-type voltage loops, respectively. , and grid-type current loop , and grid-type current loop The experimental results, including the step response waveform of the grid-type power, verified the correctness of the theoretical analysis. Figure 10 The waveform of the step response of the grid power when the given value of the d-axis current is changed shows that the oscillation intensity increases with the increase of the grid capacity, which is consistent with the theoretical analysis.

[0064] In this embodiment of the invention, through the derivation of the power transfer equation and Bode plot analysis, the influence of key factors such as inverter capacity ratio and control parameters on system damping and oscillation behavior is quantitatively characterized, providing a reliable method for the quantitative evaluation of oscillation characteristics.

[0065] Furthermore, this invention can effectively evaluate the impact of parameter changes on oscillation modes and stability margins, providing a clear and operable design basis for the optimal selection of control parameters for grid-connected and grid-connected inverters. It also possesses good versatility and scalability, and can be widely applied to heterogeneous hybrid inverter sites with different topologies and control strategies, and can be further extended to new energy power generation cluster systems composed of multiple sites.

[0066] like Figure 11 The diagram shown is a functional block diagram of a multi-machine dynamic power angle stability analysis system for inverters provided in an embodiment of the present invention.

[0067] The inverter multi-machine dynamic power angle stability analysis system 100 of the present invention can be installed in a processing device. Depending on the functions implemented, the inverter multi-machine dynamic power angle stability analysis system 100 may include a frequency domain impedance model construction module 101, a power expression construction module 102, a small-signal coefficient equation calculation module 103, a parameter frequency characteristic analysis module 104, and an analysis result determination module 105. The module described in this invention can also be called a unit, which refers to a series of computer program segments that can be executed by the processor of an electronic device and can perform a fixed function, and are stored in the memory of the electronic device.

[0068] In this embodiment, the functions of each module / unit are as follows: The frequency domain impedance model construction module 101 is used to perform small-signal modeling on grid-connected inverters and grid-connected inverters to obtain the frequency domain impedance model of the grid-connected hybrid converter station. The power expression construction module 102 is used to construct a power expression under the dynamic phasor method based on the frequency domain impedance model. The small-signal coefficient equation calculation module 103 is used to calculate the small-signal coefficient equation under the dynamic phasor method based on the power transfer equation under the dynamic phasor method. The parameter frequency characteristic analysis module 104 is used to analyze the parameter frequency characteristics of the grid-connected inverter and the grid-connected inverter according to the small signal coefficient equation. The analysis result determination module 105 is used to determine the multi-machine dynamic power angle stability analysis results of the grid-connected inverter and the grid-connected inverter based on the frequency characteristics of the parameters.

[0069] The specific execution methods for each of the above modules are the same as the corresponding execution steps in the above-mentioned multi-machine dynamic power angle stability analysis method for inverters.

[0070] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0071] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for dynamic power angle stability analysis of multi-machine inverters, characterized in that, include: Small-signal modeling was performed on grid-connected inverters and grid-connected inverters to obtain the frequency domain impedance model of the grid-connected hybrid converter station. Construct a power expression under the dynamic phasor method based on the frequency domain impedance model; The small-signal coefficient equation under the dynamic phasor method is calculated based on the power transfer equation under the dynamic phasor method. Analyze the parameter frequency characteristics of the grid-connected inverter and the grid-connected inverter based on the small-signal coefficient equation. The frequency characteristics of the parameters are used to determine the dynamic power angle stability analysis results of the multi-machine inverter for the grid-connected inverter and the grid-connected inverter.

2. The inverter multi-machine dynamic power angle stability analysis method as described in claim 1, characterized in that, The method of performing small-signal modeling on grid-connected and grid-connected inverters to obtain the frequency domain impedance model of the grid-connected hybrid converter station includes: Obtain the grid-connected inverter and the grid-connected inverter corresponding to the grid-connected hybrid converter station structure diagram; Based on the above-mentioned grid-connected hybrid converter site structure diagram, calculate the dual closed-loop equivalent output impedance of the grid-connected converter, the impedance of the grid-connected inverter, and the negative impedance introduced by the phase-locked loop. The frequency domain impedance model of the grid-connected hybrid converter station is generated based on the dual closed-loop equivalent output impedance, the grid-connected inverter impedance, and the negative impedance.

3. The inverter multi-machine dynamic power angle stability analysis method as described in claim 2, characterized in that, The calculation of the dual closed-loop equivalent output impedance of the grid-type converter, the impedance of the grid-type inverter, and the negative impedance introduced by the phase-locked loop based on the grid-connected hybrid converter site structure diagram includes: The dual closed-loop equivalent output impedance of the grid-connected converter, the grid-connected inverter impedance, and the negative impedance introduced by the phase-locked loop are calculated using the following formulas: in, This represents the dual closed-loop equivalent output impedance of a grid-type converter. Indicates filter inductance, Indicates the filter capacitor. Represents the complex frequency variable of the Laplace transform. This represents the equivalent gain of the pulse width modulation stage. This indicates a PI regulator with grid-type current closed-loop control. This represents the integral adjustment coefficient of the phase-locked loop. This represents the proportional coefficient of the proportional inner loop control in a grid-type current proportional control system. This indicates the reference value for the grid current. This represents the small-signal transfer function of a phase-locked loop. This indicates the impedance of the grid-connected inverter. This represents the negative impedance introduced by the phase-locked loop.

4. The inverter multi-machine dynamic power angle stability analysis method as described in claim 1, characterized in that, The construction of the power expression under the dynamic phasor method based on the frequency domain impedance model includes: The equivalent line impedance is obtained by performing a star-delta transformation on the frequency domain impedance model. Based on the resistive and inductive portions of the equivalent line impedance, the power expression under the dynamic phasor method is derived.

5. The inverter multi-machine dynamic power angle stability analysis method as described in claim 4, characterized in that, The step of performing a star-delta transformation on the frequency domain impedance model to obtain the equivalent line impedance includes: The equivalent line impedance is obtained by performing a star-delta transformation on the frequency domain impedance model using the following formula: in, Indicates the equivalent line impedance. This represents the dual closed-loop equivalent output impedance of a grid-type converter. Indicates the power grid impedance. Represents the complex frequency variable of the Laplace transform. Represents the imaginary unit. Indicates the rated power grid frequency. Indicates the inductance of the power grid. Represents equivalent line impedance The real part, Represents equivalent line impedance The imaginary part, This indicates the impedance of the grid-connected inverter. This indicates negative impedance.

6. The inverter multi-machine dynamic power angle stability analysis method as described in claim 1, characterized in that, The calculation of the small-signal coefficient equation under the dynamic phasor method based on the power transfer equation includes: The small-signal coefficient equation is expressed as: in, , , , They represent the small-signal coefficients, , Let these represent the active and reactive power transferred by the power source in the power transfer equation, respectively. Indicates the equivalent work angle. This indicates the magnitude of the electromotive force of the power source. Represents equivalent line impedance The real part, Represents equivalent line impedance The imaginary part.

7. The inverter multi-machine dynamic power angle stability analysis method as described in claim 1, characterized in that, The step of analyzing the parameter frequency characteristics of the grid-connected inverter and the grid-connected inverter based on the small-signal coefficient equation includes: Construct a Bode plot for each small-signal coefficient in the small-signal coefficient equation; The frequency characteristics of the parameters are analyzed based on the Bode plot.

8. A multi-machine dynamic power angle stability analysis system for inverters, characterized in that, include: The frequency domain impedance model construction module is used to perform small-signal modeling on grid-connected inverters and grid-connected inverters to obtain the frequency domain impedance model of the grid-connected hybrid converter station. A power expression construction module is used to construct a power expression under the dynamic phasor method based on the frequency domain impedance model. The small-signal coefficient equation calculation module is used to calculate the small-signal coefficient equation under the dynamic phasor method based on the power transfer equation under the dynamic phasor method. The parameter frequency characteristic analysis module is used to analyze the parameter frequency characteristics of the grid-connected inverter and the grid-connected inverter based on the small-signal coefficient equation. The analysis result determination module is used to determine the multi-machine dynamic power angle stability analysis results of the grid-connected inverter and the grid-connected inverter based on the frequency characteristics of the parameters.

9. A processing device, characterized in that, It includes at least one processor and at least one memory communicatively connected to the processor, wherein: the memory stores program instructions executable by the processor, and the processor can execute the method as described in any one of claims 1-7 by invoking the program instructions.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that cause the computer to perform the method as described in any one of claims 1-7.

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