Power angle stability collaborative control method for grid-forming and grid-following hybrid systems considering current-limiting constraints

Abstract

The application discloses a kind of considering current limiting constraint's follow network construction network hybrid system power angle stability collaborative control method.Belongs to the field of power system and power electronic control technology.This method is aimed at the power angle instability problem caused by current limiting of construction network type converter under power grid fault, by establishing the transient analysis model of hybrid system considering ring current limiting link, the nonlinear influence of current limiting on power transmission characteristics and the action mechanism of key control parameters are revealed, and a kind of collaborative control strategy based on real-time power angle deviation feedback is designed.The strategy effectively offsets the power angle deviation caused by fault and current limiting by coordinating the output current of follow network type converter and the active power reference value of construction network type converter.This application is suitable for hybrid grid-connected system mainly with new energy converter, aims to solve the technical problems of insufficient power angle stability control under current limiting constraint of existing method, and provides an effective solution for improving system transient stability and fault ride-through capability.

Description

Technical Field

[0001] This invention relates to the field of power system and power electronic control technology, specifically to a method for coordinated control of power angle stability in a grid-connected hybrid system considering current limiting constraints. Background Technology

[0002] With the increasing proportion of new energy power generation, power sources using power electronic converters as interfaces are gradually becoming the mainstay of the power grid. Grid-connected converters rely on phase-locked loops (PLLs) for grid connection, resulting in weaker inertia and voltage support capabilities. Grid-connected converters, by simulating the operating characteristics of synchronous power sources, can provide voltage support and inertia response, representing an important future development direction for power systems. In actual operation, grid-connected and grid-connected converters are typically connected to the grid in parallel, forming a hybrid system. Under disturbances such as voltage dips or short-circuit faults, the system exhibits strongly coupled and highly nonlinear dynamic characteristics. Specifically, current injection from the grid-connected converter alters the voltage characteristics at the grid connection point, causing a significant shift in the system's power angle, which can lead to loss of synchronization in severe cases.

[0003] Existing research indicates that current limiting strategies alter the power output characteristics of grid-connected converters, distorting the power-power angle relationship and even causing the disappearance of the stable equilibrium point. Furthermore, the active and reactive current distribution in grid-connected converters affects the grid connection point voltage through line impedance, further influencing the power angle dynamics of the grid-connected converter. However, existing methods primarily improve stability from the perspective of power or voltage regulation, lacking direct control methods with power angle as the core variable, and also lacking a multi-converter coordinated regulation mechanism under current-limiting constraints.

[0004] Therefore, it is necessary to propose a collaborative control method that considers current limiting constraints in order to achieve power angle stability of grid-type converters. Summary of the Invention

[0005] To address the aforementioned shortcomings in existing technologies, this invention proposes a grid-following inverter-based resource (GFM-IBR) power angle stabilization method that considers current limiting constraints. The core of this method lies in the synergistic effect of current regulation by the GFL-IBR and power regulation by the grid-following inverter to offset power angle deviations caused by faults and current limiting, thereby achieving stable system operation.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for coordinated control of power angle stability in a grid-connected hybrid system considering current limiting constraints includes the following steps: S1. For a hybrid system including grid-connected converters and grid-connected converters, a transient analysis model considering the current limiting element of the grid-connected converter is constructed. S2. Based on the model constructed in step S1, analyze the power angle stability characteristics of the hybrid system under disturbance and current limiting conditions; S3. Based on the stability analysis results of step S2, determine the key control parameters that affect the power angle stability of the grid-type converter; S4. Design a collaborative control strategy based on power angle deviation feedback, which coordinates and adjusts the output current of the grid-connected converter and the power reference value of the grid-connected converter to maintain the power angle stability of the grid-connected converter under grid fault and current limiting conditions.

[0007] Furthermore, step S1 specifically includes: S11. Establish a reduced-order transient analysis model for the hybrid system, wherein the power angle dynamics of the grid-type converter satisfies the swing equation:

[0008] In the formula, For virtual inertia, For GFM-IBR power angle, and These are the active power reference value and actual output power of the GFM-IBR, respectively. The rated angular frequency, The damping coefficient; For time; S12. Establish a mathematical model of the grid-type converter under the ring current limiting strategy. The ring current limiting strategy limits the current to the maximum allowable current by scaling the dq-axis current command proportionally. The current command after current limiting is:

[0009] In the formula: and The d-axis and q-axis current commands after current limiting by the GFM-IBR. This is the maximum allowable current for the GFM-IBR. This refers to the current phasor amplitude of the GFM-IBR. This is the scaling factor; S13. The ring current limiting process of the grid-type converter is equivalent to connecting a time-varying virtual resistor in series at its voltage source output terminal. , is represented as:

[0010] In the formula, This refers to the amplitude of the GFM-IBR terminal voltage. The voltage amplitude at the grid connection point. For GFM-IBR power angle, The equivalent impedance of the power grid. This is the current reference phasor for the GFM-IBR.

[0011] Furthermore, step S2 specifically includes the following steps: S21, Introduce equivalent voltage vector To analyze the output current of the grid-connected converter The equivalent voltage vector is defined as the effect on system characteristics:

[0012] In the formula, This is the corrected equivalent GFM voltage vector. For the grid connection point voltage phasor, for Compared to phase angle, These are the d-axis and q-axis components of the output current of the grid-connected converter, respectively. These are the resistive and reactive components of the equivalent impedance of the power grid, respectively. The imaginary unit; S22, Based on equivalent voltage vector Derive the power angle threshold for current limiting of the grid-type converter, i.e., the current limiting trigger angle. :

[0013] In the formula, The voltage amplitude of the power grid. This refers to the maximum allowable current of the GFM-IBR; S23. Derive the active power output characteristics of the grid-type converter in ring current limiting mode. :

[0014] In the formula, The phase angle of the voltage at the grid connection point. Active power injected into the grid-connected converter; Analysis of active power output characteristics based on the phase plane method The characteristics of the grid-type converter under current-limiting conditions are revealed, showing that the power angle characteristics exhibit saturation features and their impact on transient synchronous stability.

[0015] Furthermore, in step S3, based on the stability analysis in step S2, the key control parameters affecting the stability of the power angle are determined to include: reducing the active current injection of the grid-connected converter. Increase its reactive current injection And reduce the active power reference value of grid-type converters. All of these are beneficial to improving the transient stability of the hybrid system under current-limited conditions.

[0016] Furthermore, step S4 specifically includes the following steps: S41. When the low-voltage ride-through is triggered in the hybrid system, record the initial power angle of the grid-connected converter. Initial power angle of grid-type converter ; S42. Real-time acquisition of the current power angle of the grid-type converter. Current power angle of grid-connected converter And calculate the deviation between it and the corresponding initial power angle. and :

[0017]

[0018] S43, based on the aforementioned power angle deviation The active current reference value for grid-connected converters To perform inhibitory regulation; S44, Based on the stated power angle deviation Reference value of active power for grid-type converters Dynamic inhibition and regulation are performed.

[0019] The present invention has the following beneficial effects: Compared with existing technologies, this invention takes the power angle stability of the grid-connected converter as the core control objective. Under current limiting constraints and grid fault disturbances, it achieves effective control of the system's dynamic behavior through the coordinated adjustment of the grid-connected and grid-connected converters. By adjusting the output current component of the grid-connected converter, the system's voltage support capability is enhanced and unfavorable active power injection is suppressed. At the same time, in conjunction with the dynamic correction of the power command of the grid-connected converter, the system operating point is always maintained near the stable equilibrium point, thereby avoiding the power angle divergence problem caused by current limiting.

[0020] Furthermore, this invention can effectively reduce the impact of current limiting on the system's power transmission characteristics when the grid-connected converter enters or approaches the current limiting state, delay the disappearance of the stable equilibrium point, and improve the system's transient stability margin. Simultaneously, it can significantly improve the system's fault ride-through capability under fault conditions such as voltage dips. Compared to traditional control methods, this invention fully utilizes the rapid adjustment capability of the grid-connected converter to achieve coordinated and optimized operation among multiple converters, demonstrating significant engineering application value. Attached Figure Description

[0021] Figure 1 This is a topology diagram of a hybrid network system according to an embodiment of the present invention.

[0022] Figure 2 This is a control block diagram of GFL-IBR according to an embodiment of the present invention.

[0023] Figure 3 This is a control block diagram of GFM-IBR according to an embodiment of the present invention.

[0024] Figure 4 This is an equivalent circuit diagram of a network-structured hybrid system according to an embodiment of the present invention.

[0025] Figure 5 This invention relates to the influence of the output power of the GFL-IBR and the active power reference value of the GFM-IBR on the output characteristics of the GFM-IBR in an embodiment of the present invention.

[0026] Figure 6 This invention relates to the influence of the output power of GFL-IBR and the active power reference value of GFM-IBR on the phase trajectory of GFM-IBR in an embodiment of the present invention.

[0027] Figure 7 This is a schematic diagram of the collaborative control strategy for a hybrid network system considering current limiting, as described in an embodiment of the present invention.

[0028] Figure 8 The waveform of the system under the collaborative control strategy of the network-connected hybrid system taking into account current limiting in the embodiment of the present invention is shown. Detailed Implementation

[0029] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0030] A method for coordinated control of power angle stability in a grid-connected hybrid system considering current limiting constraints includes the following steps: S1. For a hybrid system including grid-connected converters and grid-connected converters, a transient analysis model considering the current limiting element of the grid-connected converter is constructed. First, a reduced-order model suitable for transient stability analysis of hybrid grid-connected systems is constructed. Based on the principle of time-scale separation, the GFL-IBR is simplified: considering that its phase-locked loop bandwidth is usually much higher than that of the GFM-IBR power synchronization loop bandwidth, its internal fast electromagnetic transient process is ignored in the transient synchronization stability analysis. It is assumed that during the fault period, the GFL-IBR can instantaneously track the PCC voltage phase dominated by the GFM-IBR. At this time, the system power angle dynamically satisfies the swing equation: (1) In the formula, For virtual inertia, For GFM-IBR power angle, and These are the active power reference value and actual output power of the GFM-IBR, respectively. The rated angular frequency, is the damping coefficient.

[0031] When the GFM-IBR adopts a ring current limiting strategy, it keeps the current vector direction unchanged and scales it proportionally. The shaft current component is limited to within the upper current limit circle. The current command after current limiting is: (2) In the formula: and The d-axis and q-axis current commands after current limiting by the GFM-IBR. This is the maximum allowable current for the GFM-IBR. This refers to the current phasor amplitude of the GFM-IBR. This is the scaling factor.

[0032] The current limiting process is physically equivalent to connecting a time-varying virtual resistor in series at the output of the voltage source. Its expression is: (3) In the formula: This refers to the amplitude of the GFM-IBR terminal voltage. The voltage amplitude at the grid connection point. For GFM-IBR power angle, The equivalent impedance of the power grid. This is the current reference phasor for the GFM-IBR.

[0033] Therefore, when the GFM-IBR is in an unlimited steady state or adopts a ring current limiting strategy, the GFM-IBR is equivalent to a controlled voltage source, and its source voltage under ring current limiting can be characterized as the equivalent output after taking into account the voltage drop of the virtual resistor.

[0034] S2. Based on the model constructed in step S1, analyze the power angle stability characteristics of the hybrid system under disturbance and current limiting conditions; Under steady-state conditions, GFM-IBR can be equivalent to an amplitude of Phase angle is A controlled voltage source. Based on PCC power balance, its active power output is: (4) In the formula, Active power injected into GFL ( ).

[0035] After the fault occurs, the output current of the GFM rises rapidly, and its current limiting trigger condition is: (5) In the formula: For grid current phasors, This refers to the output current phasor of the GFL-IBR.

[0036] To analyze the impact of GFL injection current, an equivalent voltage is introduced: (6) In the formula: This is the corrected equivalent GFM voltage vector. For the grid connection point voltage phasor, for Compared to The phase angle.

[0037] This leads to the current limiting trigger angle. : (7) This formula provides a clear current limiting trigger boundary: when the PCC power angle exceeds this threshold, GFM will enter current limiting mode.

[0038] Combined with the given equation (4) The active power output characteristics of GFM in ring current limiting mode can be derived from the definition: (8) The above equation reveals the nonlinear correction mechanism of ring current limiting for power transfer. In the non-current-limiting region, The system follows the ideal voltage source. - Sine wave characteristics. Once entering the current-limiting region, with the power angle... Increase The rapid increase makes the actual output active power It deviates significantly from the ideal trajectory, exhibiting a saturation characteristic with the top "flattened," thereby weakening the transient synchronization stability of the system.

[0039] S3. Based on the stability analysis results of step S2, determine the key control parameters that affect the power angle stability of the grid-type converter; Further analysis using the phase plane method revealed the impact of different control parameters and current distribution strategies on system transient stability. Key factors affecting power angle stability were identified, and comprehensive analysis determined that reducing active current injection and increasing reactive current injection by the GFL-IBR positively impacts the transient stability of the GFM-IBR under ring current limiting, primarily by sharing the power output of the GFM-IBR and providing voltage support. However, the relatively large active power reference value of the GFM-IBR reduces the system's transient stability margin, making it more susceptible to instability during faults. Therefore, in hybrid grid-connected systems, coordinating the power output of the GFL-IBR and optimizing the power reference settings of the GFM-IBR can effectively improve the system's transient stability under ring current limiting mode.

[0040] S4. Design a collaborative control strategy based on power angle deviation feedback, which coordinates and adjusts the output current of the grid-connected converter and the power reference value of the grid-connected converter to maintain the power angle stability of the grid-connected converter under grid fault and current limiting conditions.

[0041] Based on the above transient stability analysis results, it can be seen that reducing the active current injection of the grid-connected converter, increasing its reactive current injection, and appropriately lowering the active power reference value of the grid-connected converter are all beneficial to suppressing power angle divergence and improving system transient stability. Accordingly, this invention proposes a collaborative control strategy based on power angle deviation: When the system triggers a low-voltage ride-through, the voltage phase angle at the grid connection point is recorded as the reference power angle. The system acquires the current power angle of both grid-connected and grid-linked converters in real time and calculates the power angle deviation. Based on this deviation, the output current of the grid-linked converter is adjusted in a coordinated manner to reduce the active current component, thereby improving the voltage support capability at the grid connection point. On the other hand, the active power reference value of the grid-connected converter is suppressed and adjusted to reduce its accelerating effect on the power angle, effectively suppressing system power angle fluctuations.

[0042] For GFL-IBR, record the power angle of GFL-IBR at the moment the system triggers low-voltage ride-through. As a reference power angle, it is used in conjunction with the current power angle of the grid-type converter obtained in real time. Compare and calculate the power angle deviation: (9) In the formula, For GFL-IBR power angle deviation, For GFL-IBR power angle, The phase angle of the grid connection point voltage during low-voltage ride-through.

[0043] Considering that the reactive current output of the GFL-IBR is constrained by national standards, the power angle of the GFL-IBR is adjusted by regulating the active current. The active current of the GFL-IBR is suppressed and regulated to reduce the accelerating effect of the active current on the power angle.

[0044] For GFM-IBR, record the power angle of GFM-IBR at the moment the system triggers low-voltage ride-through. As a reference power angle, it is used in conjunction with the current power angle of the grid-type converter obtained in real time. Compare and calculate the power angle deviation: (10) In the formula, For GFM-IBR power angle deviation, For GFM-IBR power angle, The phase angle of the grid connection point voltage during low-voltage ride-through.

[0045] For GFM-IBR, a reasonable active power reference value is crucial for the existence of the system equilibrium point. Under the condition of GFL-IBR adaptively adjusting the active current, GFM-IBR... The active power reference value of GFM-IBR is dynamically adjusted to reduce the accelerating effect of excessively high active power reference values ​​on the power angle, and ultimately achieves the dynamic return of the grid-type converter operating point to the stable equilibrium point, effectively improving the transient stability of the hybrid system.

[0046] Figure 1 This is a topology diagram of a hybrid interconnected network system. Among them, and These are the inductor current phasors for GFL-IBR and GFM-IBR, respectively. The voltage phasor at the point of common coupling. For grid voltage phasors, The equivalent impedance of the power grid. It is the imaginary unit.

[0047] Figure 2 This is the control block diagram for GFL-IBR. Among them, This represents the instantaneous value of the GFL-IBR inductor current. This is the instantaneous value of the grid connection point voltage. For GFL-IBR filter inductors, and For the d-axis and q-axis components of the GFL-IBR port voltage phasor, and For the d-axis and q-axis components of the GFL-IBR inductor current phasor, and These are the proportional and integral coefficients of the phase-locked loop, respectively, and s is the differential operator. and These are the rated angular frequency and the GFL-IBR voltage angular frequency, respectively. For GFL-IBR power angle, and These are the d-axis and q-axis components of the GFL-IBR current reference phasor, respectively. and These are the d-axis and q-axis components of the current reference phasor after GFL-IBR triggers LVRT, respectively. and These represent the actual active power and reactive power output of the GFL-IBR, respectively. and These are the active power reference value and reactive power reference value of GFL-IBR, respectively. PWM is the pulse width modulator, and PI is the proportional-integral regulator.

[0048] Figure 3 This is the control block diagram for GFM-IBR. Among them, This represents the instantaneous value of the inductor current of the GFM-IBR. This is the instantaneous output current value of the GFM-IBR. This is the instantaneous value of the grid connection point voltage. It is a GFM-IBR filter inductor. This represents the actual active power output of the GFM-IBR. This is the active power reference value for GFM-IBR. Here, J is the damping coefficient of the GFM-IBR, J is the virtual inertia of the GFM-IBR, and s is the differential operator. For GFM-IBR power angle, This is the voltage reference amplitude for the GFM-IBR. and These are the d-axis and q-axis components of the voltage phasor at the grid connection point, respectively. and These are the d-axis and q-axis components of the output current phasor of the GFM-IBR, respectively. and These are the d-axis and q-axis components of the GFM-IBR current reference phasor, respectively. and These are the d-axis and q-axis components of the current reference phasor after current limiting by the GFM-IBR, respectively. and These are the d-axis and q-axis components of the inductor current phasor of the GFM-IBR, respectively.

[0049] Figure 4 This is the equivalent circuit diagram for a network-connected hybrid system. Among them, The current amplitude of the GFL-IBR equivalent current source. The phase angle of the voltage at the grid connection point. The angle between the GFL-IBR currents, The voltage amplitude at the grid connection point. For the output current phasor of GFM-IBR, The equivalent impedance magnitude of the power grid. The equivalent impedance angle of the power grid. This represents the voltage amplitude of the power grid.

[0050] Figure 5 The impact of GFL-IBR output and GFM-IBR active power reference values ​​on the output characteristics of GFM-IBR. Figure 6 The impact of GFL-IBR output and GFM-IBR active power reference value on GFM-IBR phase trajectory is analyzed. Comprehensive analysis shows that reducing active current injection and increasing reactive current injection by the GFL-IBR positively affects the transient stability of the GFM-IBR under ring current limiting, mainly by sharing the power output load of the GFM-IBR and providing voltage support. However, the relatively large active power reference value of the GFM-IBR itself reduces the system's transient stability margin, making it more prone to instability during faults. Therefore, in hybrid grid-connected systems, coordinating the power output of the GFL-IBR and optimizing the power reference setting of the GFM-IBR can effectively improve the system's transient stability under ring current limiting mode.

[0051] Figure 7 To take into account the coordinated control strategy of the grid-connected hybrid system with current limiting, after a grid fault, the GFM-IBR and GFL-IBR respectively collect the phase angle of the grid connection point voltage at the moment of triggering low voltage ride-through. Voltage phase angle during fault By comparison and This is used to adjust the active power reference value of GFM-IBR and the output current of GFL-IBR, so that the fault power angle balance point approaches the initial power angle balance point, maintain the power angle stability of the hybrid system, and effectively suppress oscillation.

[0052] Figure 8 The waveform in the figure is the system waveform under the coordinated control strategy of the grid-connected hybrid system, taking current limiting into account. The hybrid system was simulated in the time domain using MATLAB under the following conditions: the hybrid system initially operates in a steady state. At 0.4s, the grid voltage drops to 0.3pu, at which point the GFM-VSC triggers current limiting. Compared to traditional control strategies, the proposed coordinated control strategy for the grid-connected hybrid system can adaptively adjust the power reference value of the GFM-IBR and the output current of the GFL-IBR after a fault, quickly maintaining the power angle stability of the hybrid system and effectively improving the transient stability of the hybrid system during faults.

[0053] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0054] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0055] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0056] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0057] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for coordinated control of the power angle stability of a grid-connected hybrid system considering current limiting constraints, characterized in that, Includes the following steps: S1. For a hybrid system including grid-connected converters and grid-connected converters, a transient analysis model considering the current limiting element of the grid-connected converter is constructed. S2. Based on the model constructed in step S1, analyze the power angle stability characteristics of the hybrid system under disturbance and current limiting conditions; S3. Based on the stability analysis results of step S2, determine the key control parameters that affect the power angle stability of the grid-type converter; S4. Design a collaborative control strategy based on power angle deviation feedback, which coordinates and adjusts the output current of the grid-connected converter and the power reference value of the grid-connected converter to maintain the power angle stability of the grid-connected converter under grid fault and current limiting conditions.

2. The power angle stability cooperative control method for a grid-connected hybrid system considering current limiting constraints according to claim 1, characterized in that, Step S1 specifically includes: S11. Establish a reduced-order transient analysis model for the hybrid system, wherein the power angle dynamics of the grid-type converter satisfies the swing equation: In the formula, For virtual inertia, For GFM-IBR power angle, and These are the active power reference value and actual output power of the GFM-IBR, respectively. The rated angular frequency, The damping coefficient; For time; S12. Establish a mathematical model of the grid-type converter under the ring current limiting strategy. The ring current limiting strategy limits the current to the maximum allowable current by scaling the dq-axis current command proportionally. The current command after current limiting is: In the formula: and The d-axis and q-axis current commands after current limiting by the GFM-IBR. This is the maximum allowable current for the GFM-IBR. This refers to the current phasor amplitude of the GFM-IBR. This is the scaling factor; S13. The ring current limiting process of the grid-type converter is equivalent to connecting a time-varying virtual resistor in series at its voltage source output terminal. , is represented as: In the formula, This refers to the amplitude of the GFM-IBR terminal voltage. The voltage amplitude at the grid connection point. For GFM-IBR power angle, The equivalent impedance of the power grid. This is the current reference phasor for the GFM-IBR.

3. The power angle stability cooperative control method for a grid-connected hybrid system considering current limiting constraints according to claim 1, characterized in that, S2 specifically includes the following steps: S21, Introduce equivalent voltage vector To analyze the output current of the grid-connected converter The equivalent voltage vector is defined as the effect on system characteristics: In the formula, This is the corrected equivalent GFM voltage vector. For the grid connection point voltage phasor, for Compared to phase angle, These are the d-axis and q-axis components of the output current of the grid-connected converter, respectively. These are the resistive and reactive components of the equivalent impedance of the power grid, respectively. The imaginary unit; S22, Based on equivalent voltage vector Derive the power angle threshold for current limiting of the grid-type converter, i.e., the current limiting trigger angle. : In the formula, The voltage amplitude of the power grid. This refers to the maximum allowable current of the GFM-IBR; S23. Derive the active power output characteristics of the grid-type converter in ring current limiting mode. : In the formula, The phase angle of the voltage at the grid connection point. Active power injected into the grid-connected converter; Analysis of active power output characteristics based on the phase plane method The characteristics of the grid-type converter under current-limiting conditions are revealed, showing that the power angle characteristics exhibit saturation features and their impact on transient synchronous stability.

4. The power angle stability cooperative control method for a grid-connected hybrid system considering current limiting constraints according to claim 1, characterized in that, In step S3, based on the stability analysis in step S2, the key control parameters affecting the stability of the power angle are determined to include: reducing the active current injection of the grid-connected converter. Increase its reactive current injection And reduce the active power reference value of grid-type converters. All of these are beneficial to improving the transient stability of the hybrid system under current-limited conditions.

5. The method for coordinated control of power angle stability in a grid-connected hybrid system considering current limiting constraints as described in claim 1, characterized in that, S4 specifically includes the following steps: S41. When the low-voltage ride-through is triggered in the hybrid system, record the initial power angle of the grid-connected converter. Initial power angle of grid-type converter ; S42. Real-time acquisition of the current power angle of the grid-type converter. Current power angle of grid-connected converter And calculate the deviation between it and the corresponding initial power angle. and : S43, based on the aforementioned power angle deviation The active current reference value for grid-connected converters To perform inhibitory regulation; S44, Based on the stated power angle deviation Reference value of active power for grid-type converters Dynamic inhibition and regulation are performed.

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