Port Hamiltonian energy-based transient synchronization stability evaluation method and device for multi-parallel network-following converter system

Abstract

The invention belongs to the field of new energy grid connection, relates to a port Hamiltonian energy-based multi-parallel grid-following converter system transient synchronization stability evaluation method and device, and solves the problem of multi-parallel grid-following converter system transient synchronization stability evaluation at the present stage, and the method comprises the steps of establishing a transient model of a multi-parallel grid-following converter system; constructing an energy function of the transient model of the multi-parallel network-following converter system, and further establishing a port Hamiltonian model; the critical energy threshold value of the multi-parallel grid-following converter system is determined by analyzing the maximum value of the total energy in the first swing process of the fault trajectory by using a dominant unstable equilibrium point method, and the critical clearing time is further determined based on the threshold value. According to the method, internal measurement data or model parameters are not needed, and the stability margin of the multi-parallel grid-following type converter system can be accurately and quantitatively evaluated.

Description

Technical Field

[0001] This invention relates to the field of power system stability analysis, and in particular to a method and apparatus for evaluating the transient synchronization stability of a multi-parallel grid-connected converter system based on port Hamiltonian energy. Background Technology

[0002] With the increasing proportion of renewable energy, power electronic converters are playing an increasingly important role in the interface between renewable energy and the power grid. Typically, converters achieve synchronization with the grid through phase-locked loop (PLL) control. However, the PLL synchronization process is significantly affected by its nonlinear characteristics and coupling interactions with other PLLs. Currently, research on the transient synchronization stability of multi-parallel grid-connected converters is relatively limited, and the nonlinear coupling interactions between PLLs complicate the analysis and evaluation of transient synchronization stability. Existing research mainly focuses on analyzing the impact of the phase angle and amplitude of the injected current on the transient synchronization stability of multi-parallel grid-connected converters using the equal-area criterion method. Some studies also use a unified nonlinear model and a double-iteration equal-area criterion method to explore the impact of power interaction and damping on the stability of multi-parallel grid-connected converters. However, existing methods heavily rely on the model parameters of multi-parallel grid-connected converters, and the models are complex and difficult to implement in practical applications. Furthermore, the equal-area criterion method fails to fully represent the control characteristics of the PLLs and cannot accurately analyze the impact of coupling interactions on the transient synchronization stability of multi-parallel grid-connected converters.

[0003] Furthermore, the port Hamiltonian model has been successfully applied to synchronous generator and converter systems. The converter port Hamiltonian model established using port Hamiltonian theory has clear physical meaning. Simultaneously, the port energy concept proposed based on port Hamiltonian theory requires only local measurement information to accurately locate the oscillation source. However, a method for evaluating the transient synchronization stability of multi-parallel grid-type converters based on the port Hamiltonian model has not yet been reported.

[0004] Application content

[0005] Based on the above analysis, this invention aims to provide a transient synchronization stability assessment method for multi-parallel grid-connected converter systems based on port Hamiltonian energy. This method enables quantitative assessment of the transient synchronization stability of multi-parallel grid-connected converter systems without requiring internal measurement data or model parameters, thus addressing the issue of stable system operation after new energy grid integration.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] A transient synchronization stability assessment method for a multi-parallel grid-connected converter system based on port Hamiltonian energy includes:

[0008] Step S1: Establish a transient model of a multi-parallel grid-connected converter system;

[0009] Step S2: Construct the energy function of the transient model of the multi-parallel grid-type converter system, and further establish the port Hamiltonian model;

[0010] Step S3: Using the dominant unstable equilibrium point method, the critical energy threshold of the multi-parallel grid-connected converter system is determined by analyzing the maximum value of the total energy during the initial swing of the fault trajectory, and the critical clearance time is further determined based on the critical energy threshold.

[0011] Preferably, step S1, establishing a transient model of the multi-parallel grid-connected converter system, includes: establishing a transient model of the multi-parallel grid-connected converter system in a new energy power plant, using phase-locked loop control as the control variable. If The state-space model of the i-th grid converter can be expressed as:

[0012]

[0013] The parameters are defined as follows:

[0014]

[0015] Among them, U g ∠0 represents the infinite grid bus voltage; each grid-type converter i, where i = 1, 2, ... n, is connected to a filter inductor L. fi and filter capacitor C fi Connected to the power grid; equivalent line impedance Z si =Z i +Z g Z i and Z g These represent the grid-side impedance and the grid-side impedance, respectively; M i D represents equivalent inertia; ji and D i Indicates equivalent damping; U g sinδ i The influence reflecting the grid voltage state is defined as the grid synchronization term; U tqii The term represents the interaction between the output current of the i-th grid converter and the line impedance, and is defined as a self-synchronization term; U tqji The interaction between different converters is defined as a coupling synchronization term.

[0016] Preferably, step S2 includes:

[0017] Step S201: Based on the second-order differential equation of the transient model of the multi-parallel grid-type converter system, construct the energy function H(x) corresponding to the model, i.e. the port Hamiltonian energy function, and differentiate the constructed port Hamiltonian energy function H(x). Based on the Hamiltonian controlled system model, establish the port Hamiltonian model of the multi-parallel grid-type converter system.

[0018] Step S202: Derive the system damping matrix R(x), interconnection matrix J(x), input variable control matrix g(x), and additional term p(x); derive the specific parameters of the port Hamiltonian mathematical model corresponding to the established multi-parallel grid-type converter system;

[0019] Step S203: Based on the power and voltage equations of the machine-grid interface and the Hamiltonian model of the multi-parallel grid-connected converter system port, derive the port measurable energy function.

[0020] Preferably, the port Hamiltonian energy function is first established:

[0021]

[0022] Taking the partial derivatives of H(x) with respect to the state variables ω and δ, the result is:

[0023]

[0024] Referring to the equations of the generalized port Hamiltonian system model:

[0025]

[0026] And based on the established transient model equations of the multi-parallel grid-type converter system:

[0027]

[0028] Establish a Hamiltonian model for the ports of a multi-parallel grid-connected converter system:

[0029]

[0030] in, J represents the gradient of the state variable with respect to time. i (x) is the system interconnection matrix, which is partially symmetric. R is a column vector of partial derivatives; i (x) is the system damping matrix, if R i If (x) is not negative, then the port Hamiltonian model is stable, i.e. u and y are conjugate variables, representing the input and output vectors respectively; g(x) is the input variable control matrix; g T p(x) is its transpose matrix; p(x) is an additional term.

[0031] Preferably, it includes the system damping matrix R. i (x), System interconnection matrix J i The input variable control matrix g(x) and the additional term p(x) are respectively:

[0032]

[0033] The final output equation is:

[0034]

[0035] That is, the specific parameters of the Hamiltonian controlled system corresponding to the established multi-parallel grid-type converter system of port Hamiltonian energy were derived.

[0036] Preferably, the power and voltage equations are further based on the machine-to-network interface:

[0037]

[0038] And the Hamiltonian model of the port of a multi-parallel grid-connected converter system:

[0039]

[0040] Derive the measurable energy function based on the grid-connected converter port:

[0041]

[0042] Therefore, the port energy function of a multi-grid converter system is:

[0043]

[0044] Preferably, step S3 includes determining the critical energy threshold using the dominant unstable equilibrium point method, defining the maximum potential energy during the initial swing of the fault trajectory as the critical energy threshold, and further determining the critical clearance time based on the critical energy threshold.

[0045] Preferably, the transient synchronization stability assessment device for a multi-parallel grid-connected converter system based on port Hamiltonian energy includes:

[0046] The data acquisition module is used to obtain the initial operating status of the system before the fault occurs and to obtain the electrical quantity data of each grid-type converter bus in the system required for subsequent calculations; by monitoring the lines and nodes, it determines whether there is a three-phase short circuit fault in the power system; after fault detection, it collects power and voltage phase angle signals through PMUs distributed at the nodes.

[0047] The calculation module is used to process and calculate the electrical quantity data of each grid converter in the system acquired by the acquisition module, and to calculate the continuous fault trajectory of the grid converter after the fault using the port energy equation, and to identify the dominant type.

[0048] The comparison module is used to compare and analyze the calculation results of the calculation module, and to search along the continuous fault trajectory to obtain the critical energy value of the system. It compares the total transient port energy obtained by the calculation module at the fault clearing time with the critical energy value, thereby quantitatively identifying the stability margin of the multi-parallel grid-connected converter system.

[0049] The feedback module provides useful feedback to the decision support system. It feeds back the compared total transient energy and critical energy of the system to the system data center.

[0050] Beneficial effects

[0051] This invention can quantitatively assess the transient synchronization stability margin of a multi-parallel grid-connected converter system based on port Hamiltonian energy. By analyzing the maximum total energy during the initial swing of the fault trajectory using the dominant unstable equilibrium point method, it determines the critical energy threshold of the multi-parallel grid-connected converter system and further determines the critical clearance time based on this threshold. Furthermore, this method does not require internal measurement data or model parameters, facilitating online application.

[0052] Those skilled in the art should understand that the above embodiments are only for illustrating the specific content of this disclosure and do not limit its scope; the system capacity, voltage, line parameters, etc. may vary depending on the specific circumstances of the power electronic grid-connected generator set and its grid connection. Based on this disclosure, those skilled in the art may make other changes or adjustments, and these changes still fall within the scope of this disclosure. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings involved in the embodiments or the prior art are briefly described below. Obviously, these drawings illustrate several embodiments of the present invention, and those skilled in the art can derive other possible drawings based on these drawings without creative effort. The purpose of the drawings is limited to illustrating specific embodiments and does not limit the scope of the present invention.

[0054] Figure 1 This is a flowchart of the transient synchronization stability evaluation method for a multi-parallel grid-connected converter system in Embodiment 1 of the present invention;

[0055] Figure 2 This is a detailed model block diagram of the multi-parallel grid-connected converter system in Embodiment 1 of the present invention;

[0056] Figure 3This is a schematic diagram of the transient synchronization stability evaluation device for a multi-parallel grid-connected converter system in Embodiment 2 of the present invention.

[0057] Figure 4 This is a detailed model block diagram of the two-machine parallel grid-connected converter system in Embodiment 3 of the present invention;

[0058] Figure 5 This is the energy change diagram in Case 1 of the two-machine parallel grid-connected converter system in Embodiment 3 of the present invention;

[0059] Figure 6 This is the energy change diagram in Case 2 of the two-machine parallel grid-connected converter system in Embodiment 3 of the present invention. Detailed Implementation

[0060] 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 with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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 protection scope of the present invention.

[0061] Example 1

[0062] This embodiment discloses a transient synchronization stability evaluation method for a multi-parallel grid-connected converter system based on port Hamiltonian energy, such as... Figures 1 to 6 As shown, it includes the following steps:

[0063] Step S1: Establish a transient model of a multi-parallel grid-connected converter system;

[0064] Based on the block diagram of the phase-locked synchronous converter model, as follows: Figure 2 As shown, the control strategy of a phase-locked synchronous converter (PLC) mainly consists of four parts: current loop, PLC, DC bus, and grid. In this system, the nonlinear characteristics of the PLC and its interactions significantly affect the transient response level (TSS). In a multi-parallel grid-connected converter model for a renewable energy power plant, a transient model of the multi-parallel grid-connected converter system is established with PLC control as the control variable. If... The state-space model of the i-th grid converter can be expressed as:

[0065]

[0066] The parameters are defined as follows:

[0067]

[0068] Among them, U g∠0 represents the infinite grid bus voltage; each grid-type converter i, where i = 1, 2, ... n, is connected to a filter inductor L. fi and filter capacitor C fi Connected to the power grid; equivalent line impedance Z si =Z i +Z g Z i and Z g These represent the grid-side impedance and the grid-side impedance, respectively; M i D represents equivalent inertia; ji and D i Indicates equivalent damping; U g sinδ i The influence reflecting the grid voltage state is defined as the grid synchronization term; U tqii The term represents the interaction between the output current of the i-th grid converter and the line impedance, and is defined as a self-synchronization term; U tqji The interaction between different converters is defined as a coupling synchronization term.

[0069] Step S2: Construct the energy function of the transient model of the multi-parallel grid-type converter system, and further establish the port Hamiltonian model;

[0070] The specific S2 includes the following steps:

[0071] Step S201: Based on the second-order differential equation of the transient model of the multi-parallel grid-type converter system, construct the energy function H(x) corresponding to the model, i.e. the port Hamiltonian energy function, and differentiate the constructed port Hamiltonian energy function H(x). Based on the generalized Hamiltonian controlled system model, establish the port Hamiltonian model of the multi-parallel grid-type converter system.

[0072] Step S202: From this, the system damping matrix R(x), interconnection matrix J(x), input variable control matrix g(x), and additional term p(x) can be further derived. Thus, the specific parameters of the port Hamiltonian mathematical model corresponding to the established multi-parallel grid-type converter system are derived.

[0073] Step S203: Based on the power and voltage equations of the machine-grid interface and the Hamiltonian model of the port of the multi-parallel grid-connected converter system, the port measurable energy function can be further derived.

[0074] First, establish the port Hamiltonian energy function:

[0075]

[0076] Where δ ij This represents the initial equilibrium point. The first term represents M. i The generated kinetic energy E kThe second term represents the potential energy E generated by a multi-parallel grid-connected converter system. p H i (x) represents the total energy E of a multi-parallel grid-connected converter system. t Then H i (x) Taking the partial derivatives with respect to the state variables ω and δ, the result is:

[0077]

[0078] Referring to the equations of the generalized port Hamiltonian system model:

[0079]

[0080] And based on the established transient model equations of the multi-parallel grid-type converter system:

[0081]

[0082] Establish a Hamiltonian model for the ports of a multi-parallel grid-connected converter system:

[0083]

[0084] in, J represents the gradient of the state variable with respect to time. i (x) is the system interconnection matrix, which is partially symmetric. R is a column vector of partial derivatives; i (x) is the system damping matrix, if R i If (x) is not negative, then the port Hamiltonian model is stable, i.e. u and y are conjugate variables, representing the input and output vectors respectively; g(x) is the input variable control matrix; g T p(x) is its transpose matrix; p(x) is an additional term.

[0085] Where the system damping matrix R i (x), System interconnection matrix J i The input variable control matrix g(x) and the additional term p(x) are respectively:

[0086]

[0087] The final output equation is:

[0088]

[0089] That is, the specific parameters of the Hamiltonian controlled system corresponding to the established multi-parallel grid-type converter system of port Hamiltonian energy were derived.

[0090] Further power and voltage equations based on the machine-to-network interface:

[0091]

[0092] And the Hamiltonian model of the port of a multi-parallel grid-connected converter system:

[0093]

[0094] Derive the measurable energy function based on the grid-connected converter port:

[0095]

[0096] Therefore, the port energy function of a multi-grid converter system is:

[0097]

[0098] Step S3 includes determining the critical energy threshold using the dominant unstable equilibrium point method. The maximum potential energy during the initial swing of the fault trajectory is defined as the critical energy threshold, and the critical clearance time is further determined based on this threshold.

[0099] Example 2

[0100] This embodiment discloses a transient synchronization stability evaluation device for a multi-parallel grid-type converter system based on port Hamiltonian energy, such as... Figure 3 As shown, it includes a data acquisition module, a calculation module, a comparison module, and a feedback module.

[0101] The data acquisition module is used to obtain the initial operating status of the system before the fault occurs and to acquire the electrical quantity data of each grid-type converter bus required for subsequent calculations; by monitoring the lines and nodes, it determines whether a three-phase short-circuit fault exists in the power system. After fault detection, power and voltage phase angle signals are acquired through PMUs distributed at the nodes;

[0102] The calculation module processes and calculates the electrical quantity data of each grid-type converter in the system acquired by the acquisition module, and uses the port energy equation to calculate the port energy of the grid-type converter after a fault. It also calculates the continuous fault trajectory and identifies the dominant fault type.

[0103] The comparison module compares and analyzes the calculation results from the computation module, searches along the continuous fault trajectory to obtain the critical energy value of the system, and compares the total transient port energy obtained by the computation module at the fault clearing time with the critical energy value. This quantitatively identifies the stability margin of the multi-parallel grid-connected converter system; determines the system's state variables at any moment during the fault process, substitutes them to obtain the total energy value Et, and denotes the limit clearing time t when Ec = Et. c .

[0104] The specific transient synchronization stability criterion for the multi - parallel grid - following converter system is as follows: Et < Ec: The transient synchronization stability of the multi - parallel grid - following converter system.

[0105] Et = Ec: The transient synchronization critical stability of the multi - parallel grid - following converter system.

[0106] Et > Ec: The transient instability of the multi - parallel grid - following converter system.

[0107] The total energy Ec of the multi - parallel grid - following converter system can be determined by an equation.

[0108] The feedback module provides useful feedback for the decision - making support system. It feeds back the compared total transient energy and critical energy of the system to the system data center.

[0109] Example 3

[0110] Using Figure 4 The two - machine parallel grid - following converter system is used to verify the transient synchronization stability evaluation method. At t = 0.5 s, a three - phase short - circuit fault occurs at the PCC, and both two - machine parallel grid - following converter systems inject negative reactive current. Non - linear simulations are carried out using DIgSILENT and PowerFactory. Table 1 gives some parameters of two research cases.

[0111] Table 1 Parameter settings of the two - machine parallel grid - following converter system

[0112]

[0113] To verify the correctness and effectiveness of this method, two cases are selected in this example to verify the proposed transient synchronization stability criterion for the multi - parallel grid - following converter system.

[0114] Evaluation of the two - machine parallel grid - following converter system: According to the transient synchronization stability evaluation criteria proposed in Example 2, the critical clearing time is determined by comparing Ec and Et. As Figure 5 and 6 shown, the transient synchronization stability criterion proposed in this example.

[0115] Derived from the port - Hamiltonian energy function, the peak potential energy at the first swing is taken as the critical energy Ec. The time when Et equals Ec is called the critical clearing time. From the simulation trajectory and the expression of the port - Hamiltonian energy function, the critical energy value Ec of Case 1 is 0.15, and the corresponding critical clearing time is 0.645 s. For Case 2, the critical energy value Ec is 0.11, and the corresponding critical clearing time is 0.637 s. In Case 1, the faults are cleared at 0.62 s and 0.646 s respectively. As Figure 5As shown in (a) and (b), when the fault is cleared at 0.62s, Et is less than Ec, and the parallel grid-connected converter system maintains transient synchronization stability. However, when the fault clearing time reaches 0.646s, Et exceeds Ec, causing transient instability in the parallel grid-connected converter system. In case 2, the fault is cleared at 0.62 seconds and 0.638 seconds, respectively. Figure 6 As shown in (a) and (b), when the fault clearing time is 0.62s, Et remains below Ec, and the two-machine parallel grid-connected converter system maintains transient synchronization stability. When the fault clearing time reaches 0.638s, Et exceeds Ec, leading to transient instability. Therefore, the case study verifies the effectiveness and correctness of the proposed transient synchronization stability criterion.

[0116] In summary, the transient synchronization stability assessment method and apparatus for multi-parallel grid-connected converter systems based on port Hamiltonian energy, constructed using this invention, solves the problems of assessment complexity and measurement difficulty caused by the numerous internal parameters of multi-parallel grid-connected converters. Considering the dynamic influence of the phase-locked loop, a transient synchronization stability criterion based on the port Hamiltonian energy function is proposed. It can accurately determine the critical cut-off time of multi-parallel grid-connected converter systems without requiring internal measurement data or model parameters. Finally, the effectiveness and reliability of the method in practical applications are verified through examples. In the future, this method will be extended to analyze and evaluate the transient synchronization stability of grid-connected converters.

[0117] Those skilled in the art should understand that the above embodiments are merely illustrative of the content of this disclosure and do not limit its scope. The system capacity, voltage, line parameters, etc., shown may vary depending on the specific circumstances of the power electronic grid-connected generator set and its grid connection. Based on this disclosure, those skilled in the art can make other changes or adjustments, and these changes still fall within the scope of this disclosure.

Claims

1. A method for evaluating the transient synchronization stability of a multi-parallel grid-connected converter system based on port Hamiltonian energy, characterized in that, include: Step S1: Establish a transient model of a multi-parallel grid-connected converter system; Step S2: Construct the energy function of the transient model of the multi-parallel grid-type converter system, and further establish the port Hamiltonian model; Step S3: Using the dominant unstable equilibrium point method, the critical energy threshold of the multi-parallel grid-connected converter system is determined by analyzing the maximum value of the total energy during the initial swing of the fault trajectory, and the critical clearance time is further determined based on the critical energy threshold.

2. The transient synchronization stability assessment method for a multi-parallel grid-type converter system based on port Hamiltonian energy according to claim 1, characterized in that, Step S1 establishes a transient model of the multi-parallel grid-connected converter system, including: establishing a transient model of the multi-parallel grid-connected converter system in a new energy power plant, using phase-locked loop control as the control variable. If The state-space model of the i-th grid converter can be expressed as: The parameters are defined as follows: Among them, U g ∠0 represents the infinite grid bus voltage; each grid-type converter i, where i = 1, 2, ... n, is connected to a filter inductor L. fi and filter capacitor C fi Connected to the power grid; equivalent line impedance Z si =Z i +Z g Z i and Z g These represent the grid-side impedance and the grid-side impedance, respectively; M i D represents equivalent inertia; ji and D i Indicates equivalent damping; U g sinδ i The influence reflecting the grid voltage state is defined as the grid synchronization term; U tqii The term represents the interaction between the output current of the i-th grid converter and the line impedance, and is defined as a self-synchronization term; U tqji The interaction between different converters is defined as a coupling synchronization term.

3. The transient synchronization stability evaluation method for a multi-parallel grid-connected converter system based on port Hamiltonian energy according to claim 1, characterized in that, Step S2 includes: Step S201: Based on the second-order differential equation of the transient model of the multi-parallel grid-type converter system, construct the energy function H(x) corresponding to the model, i.e. the port Hamiltonian energy function, and differentiate the constructed port Hamiltonian energy function H(x). Based on the Hamiltonian controlled system model, establish the port Hamiltonian model of the multi-parallel grid-type converter system. Step S202: Derive the system damping matrix R(x), interconnection matrix J(x), input variable control matrix g(x), and additional term p(x); derive the specific parameters of the port Hamiltonian mathematical model corresponding to the established multi-parallel grid-type converter system; Step S203: Based on the power and voltage equations of the machine-grid interface and the Hamiltonian model of the multi-parallel grid-connected converter system port, derive the port measurable energy function.

4. The transient synchronization stability assessment method for a multi-parallel grid-connected converter system based on port Hamiltonian energy according to claim 3, characterized in that, First, establish the port Hamiltonian energy function: Taking the partial derivatives of H(x) with respect to the state variables ω and δ, the result is: Referring to the equations of the generalized port Hamiltonian system model: And based on the established transient model equations of the multi-parallel grid-type converter system: Establish a Hamiltonian model for the ports of a multi-parallel grid-connected converter system: in, J represents the gradient of the state variable with respect to time. i (x) is the system interconnection matrix, which is partially symmetric. R is a column vector of partial derivatives; i (x) is the system damping matrix, if R i If (x) is not negative, then the port Hamiltonian model is stable, i.e. u and y are conjugate variables, representing the input and output vectors respectively; g(x) is the input variable control matrix; g T p(x) is its transpose matrix; p(x) is an additional term.

5. The transient synchronization stability evaluation method for a multi-parallel grid-type converter system based on port Hamiltonian energy according to claim 4, characterized in that, Including the system damping matrix R i (x), System interconnection matrix J i The input variable control matrix g(x) and the additional term p(x) are respectively: The final output equation is: That is, the specific parameters of the Hamiltonian controlled system corresponding to the established multi-parallel grid-type converter system of port Hamiltonian energy were derived.

6. The transient synchronization stability assessment method for multi-parallel grid-connected converter systems based on port Hamiltonian energy as described in claim 5 is further based on the power and voltage equations of the machine-grid interface: And the Hamiltonian model of the port of a multi-parallel grid-connected converter system: Derive the measurable energy function based on the grid-connected converter port: Therefore, the port energy function of a multi-grid converter system is:

7. The transient synchronization stability assessment method for a multi-parallel grid-connected converter system based on port Hamiltonian energy according to claim 1 or 6, characterized in that, Step S3 includes determining the critical energy threshold using the dominant unstable equilibrium point method. The maximum potential energy during the initial swing of the fault trajectory is defined as the critical energy threshold, and the critical clearance time is further determined based on the critical energy threshold.

8. An apparatus for evaluating the transient synchronization stability of a multi-parallel grid-connected converter system based on port Hamiltonian energy according to any one of claims 1 to 7, characterized in that, include: The data acquisition module is used to obtain the initial operating status of the system before the fault occurs and to obtain the electrical quantity data of each grid-type converter bus in the system required for subsequent calculations; by monitoring the lines and nodes, it determines whether there is a three-phase short circuit fault in the power system; after fault detection, it collects power and voltage phase angle signals through PMUs distributed at the nodes. The calculation module is used to process and calculate the electrical quantity data of each grid converter in the system obtained by the acquisition module, and to calculate the port energy of the grid converter after a fault using the port energy equation. Calculate persistent fault trajectories and identify dominant types; The comparison module is used to compare and analyze the calculation results of the calculation module, and to search along the continuous fault trajectory to obtain the critical energy value of the system. It compares the total transient port energy obtained by the calculation module at the fault clearing time with the critical energy value, thereby quantitatively identifying the stability margin of the multi-parallel grid-connected converter system. The feedback module provides useful feedback to the decision support system; it feeds back the compared total transient energy and critical energy of the system to the system data center.

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