A network-configuration type energy storage transient stability method considering joint fault and current limiting strategy

Abstract

The application discloses a network-constructed energy storage transient stability method considering joint fault and current limiting strategy, which aims at the problem that existing methods lack consideration of joint fault scenes and current limiting demands, establishes a transient model considering current limiting strategy, and corrects analysis errors caused by ignoring nonlinear links and actual application scenes in traditional transient stability improvement strategies. On the basis, the method of the application is based on power angle dynamic sensing and power compensation term design, preset trigger logic of the compensation structure, further proposes a whole-process transient stability method, perfects the transient modeling theory of the network-constructed energy storage, and provides a reference for improving synchronous stability under large disturbance. The verification waveform of the semi-physical simulation shows that the method of the application realizes the unification of effective current limitation and transient stability maintenance during the fault by coordinating current suppression and synchronous power compensation, and significantly enhances the penetration capability and power grid support reliability of the network-constructed converter under severe joint faults.

Description

Technical Field

[0001] This invention belongs to the field of new energy power generation control technology, specifically relating to a transient stabilization method for grid-type energy storage that takes into account joint faults and current limiting strategies. Background Technology

[0002] As the global energy transition deepens, renewable energy generation systems dominated by high-proportion inverters are reshaping the dynamic characteristics of power systems. In the context of a fully green power system, the power grid exhibits weak inertia and weak damping characteristics. Load imbalance and phase flicker become the main factors threatening the transient synchronous stability of grid-connected energy storage systems. Traditional power systems rely on the inherent rotational inertia and overload capacity of synchronous generators to provide crucial voltage and frequency support to the grid during faults. In contrast, while grid-connected converters based on power electronics technology simulate the external characteristics of synchronous machines through control algorithms, their physical nature is still limited by the transient tolerance of semiconductor devices. Under large grid disturbances, they are highly susceptible to damage or disconnection due to overcurrent. This contradiction makes ensuring the synchronous stability of the grid-connected control system itself while effectively limiting fault current a core challenge that must be addressed for its large-scale grid connection.

[0003] In actual power grid faults, especially the most prevalent non-metallic short-circuit faults, the transient process is far from an ideal voltage amplitude drop. The presence of transition impedance at the fault point leads to a double abrupt change in both amplitude and phase angle of the voltage at the point of common coupling. This phase flicker caused by the short-circuit impedance phase angle can cause large-angle step disturbances to the power synchronization loop of grid-based energy storage, disrupting power angle stability. Simultaneously, voltage asymmetry fluctuations caused by load imbalances further exacerbate this process, posing more complex transient stability challenges to the system. This composite fault scenario presents a more severe challenge to grid-based control: the step-like voltage phase jump directly impacts the power synchronization loop, causing violent oscillations in power and internal potential, thereby significantly increasing the peak transient current and substantially increasing the risk of energy storage protection activation and system instability.

[0004] To address overcurrent issues, existing research has proposed various current-limiting strategies. For example, the literature [X. Chen, W. Si, Q. Yu, J. Fang. Transient Stability Analysis and Enhancement of Grid-Forming Converters: A Comprehensive Review. Electronics. 14(4), 2025, 645] achieves overcurrent suppression by introducing virtual impedance, but at the same time, it smooths the power angle curve, reduces the recovery capability of synchronous torque, and weakens the transient stability capability of grid-forming energy storage. The literature [Y. Zhang, C. Zhang, R. Yang, M. Molinas, X. Cai. Current constrained power-angle characterization method for transientstability analysis of grid-forming voltage source converters. IEEE Transactions on Energy Conversion. 38(2), 2023, 1338-1349] uses a hybrid current-limiting strategy to simultaneously consider overcurrent limiting performance and large-signal stability, but it does not fully consider the severe conditions of actual combined faults.

[0005] In summary, existing technologies lack a stability improvement method that takes into account both combined faults and current limiting requirements of grid-connected energy storage. There is an urgent need to establish a transient stabilization method that combines the characteristics of combined faults with current limiting control structures to improve the transient synchronous stability capability and grid support reliability of grid-connected converters under severe real-world fault scenarios. Summary of the Invention

[0006] In view of the above, the present invention provides a transient stabilization method for grid-connected energy storage that takes into account combined faults and current limiting strategies. It can simultaneously achieve overcurrent suppression and transient synchronous stability improvement, significantly enhancing the ride-through capability of grid-connected converters under severe combined faults and the reliability of grid support.

[0007] A transient stabilization method for grid-based energy storage that takes into account joint fault and current-limiting strategies includes the following steps:

[0008] (1) For grid-connected energy storage systems, when a combined fault including voltage drop and phase angle jump occurs at the PCC (grid common coupling point), the fault characteristics are detected in real time and the current limiting strategy based on AVI (adaptive virtual impedance) is immediately triggered. The compensation voltage is generated by adjusting the resistive and inductive components of the virtual impedance online to correct the voltage reference vector of the voltage loop, thereby limiting the amplitude of the output current of the energy storage converter in the system to within the preset safety threshold.

[0009] (2) During the continuous operation of the current limiting strategy, the rate of change of the system power angle is monitored in real time, a power compensation term reflecting the transient offset characteristics is constructed, and the power compensation term is applied to the reference power input terminal or frequency feedforward terminal of the virtual synchronous machine control loop according to the preset decision logic to provide compensatory synchronous torque, thereby enhancing and maintaining the transient synchronous stability of the system.

[0010] Furthermore, the joint fault in step (1) is characterized by an equivalent voltage source in the Thevenin equivalent model, the voltage vector of which is expressed as: Its amplitude is V th The phase angle is paj - d The specific expression is as follows:

[0011]

[0012] in: V g The voltage amplitude of the power grid. Z g For grid impedance, Z ft The short-circuit impedance at PCC is... This indicates the impedance phase angle. i paj This indicates the phase jump value of the equivalent voltage source caused by the combined fault. d This represents the phase difference between the internal potential of the energy storage converter and the grid voltage vector.

[0013] Furthermore, the current limiting strategy in step (1) modifies the voltage reference vector of the voltage loop using the following expression:

[0014]

[0015]

[0016]

[0017]

[0018] in:E and E' These are the voltage reference vectors before and after the correction, respectively. V z To compensate for voltage, I c This is the output current of the energy storage converter when the ring current limiter is triggered. Z v The impedance introduced by AVI in the equivalent model. j The imaginary unit, R vt For adaptive transient virtual resistance, X vt For adaptive transient virtual reactance, R vs For adaptive steady-state virtual resistance, X vs For adaptive steady-state virtual reactance, K prt These are the transient adaptive coefficients. K prs For steady-state adaptive coefficients, s Δ is the reactance-resistance ratio of the virtual impedance. V This represents the voltage drop depth at PCC. I th The trigger threshold of the steady-state virtual impedance and I th =0.9 I lim , I lim This is the current limiting value for the ring current limiter.

[0019] Furthermore, the transient adaptive coefficients K prt The calculation expression is as follows:

[0020]

[0021] in: R f This represents the total resistance from PCC to the power grid. X f This represents the total reactance from PCC to the power grid. E ref The internal potential of the energy storage converter (i.e., the voltage reference vector before correction) E The amplitude of ).

[0022] Furthermore, the steady-state adaptive coefficient K prs The calculation expression is as follows:

[0023]

[0024] in: x tar Indicates the target damping ratio. oh n Indicates the rated angular velocity of the power grid. J This represents the equivalent inertia of the virtual synchronous machine control loop. D p This represents the equivalent damping of the virtual synchronous machine control loop. P e This refers to the output active power of the energy storage converter.

[0025] Furthermore, the output current I c The calculation expression is as follows:

[0026]

[0027]

[0028] in: Z th The impedance of the equivalent voltage source. Indicates amplitude V th Phase angle is paj - d voltage vector, R e This refers to the equivalent resistance introduced into the equivalent model when the ring current limiter is triggered. impedance Z th The phase angle.

[0029] Furthermore, the output active power P e The calculation expression is as follows:

[0030]

[0031] in: This represents the total impedance phase angle of the equivalent model under the current limiting strategy after a fault. .

[0032] Furthermore, the reactance-resistivity ratio of the virtual impedance s The value is set to a constant greater than 1, so that the injection impedance is inductively dominant, thereby maintaining a certain power angle recovery capability while limiting current.

[0033] Furthermore, the calculation expression for the power compensation term in step (2) is as follows:

[0034]

[0035] in: P adj For power compensation, V pccq This represents the q-axis voltage component at PCC. R v Represents the virtual resistance of AVI and R v = R vt + R vs , R vt For adaptive transient virtual resistance, R vs This is an adaptive steady-state virtual resistance.

[0036] Furthermore, the decision logic in step (2) is as follows:

[0037] When d d / d t When <0, it is determined that the system lacks acceleration torque, and the power compensation term is injected into the reference power input terminal of the virtual synchronous machine control loop with positive polarity;

[0038] When d d / d t When the value is greater than 0, it is determined that the system lacks damping torque, and the power compensation term is injected into the frequency feedforward terminal of the virtual synchronous machine control loop with negative polarity.

[0039] in: d This represents the phase difference between the internal potential of the energy storage converter and the grid voltage vector. t Indicates time.

[0040] A computer device includes a memory and a processor, wherein the memory stores a computer program and the processor executes the computer program to implement the above-described transient stabilization method for grid-type energy storage that takes into account joint fault and current limiting strategies.

[0041] A computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described transient stabilization method for grid-type energy storage that takes into account joint fault and current limiting strategies.

[0042] Compared with the prior art, the present invention has the following beneficial technical effects:

[0043] 1. This invention establishes a unified transient stability analysis model that takes into account both joint fault detection and adaptive current limiting strategies. Based on the Thevenin equivalent principle, it accurately characterizes the simultaneous jumps in voltage amplitude and phase angle at the grid connection point, providing a quantitative analysis basis for real-time fault feature detection and online adjustment of virtual impedance, and further providing a clear parameter design basis for current amplitude limiting strategies.

[0044] 2. This invention proposes a transient stabilization method based on dynamic power angle sensing, constructs a virtual impedance channel based on fault depth adaptive adjustment and a power compensation channel based on power angle change rate feedback, and further establishes a trigger decision logic framework for the power compensation term. This method achieves the unity of effective current limitation and transient stability maintenance during faults by coordinating current suppression and synchronous power compensation, significantly enhancing the ride-through capability of grid-connected converters under severe combined faults and the reliability of grid support. Attached Figure Description

[0045] Figure 1 This is a block diagram of the main circuit topology and control system of a grid-type energy storage system.

[0046] Figure 2 This is a schematic diagram showing the relationship between the transient modulation coefficient and the peak current of the first cycle.

[0047] Figure 3 This is a schematic diagram of the system power angle trajectory when the current limiting link is triggered under a combined fault, where (a) corresponds to the case where the short-circuit impedance is set to reactance much greater than resistance, and (b) corresponds to the case where the short-circuit impedance is set to reactance much less than resistance.

[0048] Figure 4 This is a schematic diagram illustrating the role of the power compensation term in the virtual synchronous machine control loop.

[0049] Figure 5 This is a schematic diagram illustrating the implementation process of the transient stabilization method of the present invention.

[0050] Figure 6 This is a schematic diagram of the semi-physical simulation waveform of the transient stabilization method of the present invention, where (a) corresponds to the transient waveform of the grid converter without the transient stabilization method of the present invention, and (b) corresponds to the transient waveform of the grid converter with the transient stabilization method of the present invention. The horizontal axis is time and the vertical axis is per unit value. Detailed Implementation

[0051] To describe the present invention in more detail, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] This implementation provides a transient stabilization method for grid-connected energy storage that considers both combined faults and current-limiting strategies. It aims to address the failure of stability enhancement strategies in traditional transient stability analysis that only consider a single fault. By establishing a large-signal model that takes current-limiting strategies into account and combining dynamic power angle sensing, a transient stabilization method is proposed for practical non-metallic short-circuit grounding scenarios. This improves the synchronous stability capability of grid-connected energy storage under large disturbances while also considering current-limiting strategies. The specific implementation process is as follows:

[0053] Step 1: Establish a joint fault detection and current limiting control strategy framework.

[0054] In this embodiment, we selected a grid-type converter as the verification object to demonstrate the effectiveness of the grid-type energy storage transient stabilization strategy of this invention. The main circuit topology and related control structure framework are as follows: Figure 1 As shown in the figure, the grid converter with a dual inner loop control structure for voltage and current can be equivalent to a voltage source with constant internal potential. The joint fault on the grid side can be characterized by a voltage source with controllable amplitude and phase.

[0055] (1) Joint fault model.

[0056] A combined fault involving voltage dips and phase angle jumps is characterized by voltage sources in an equivalent model. The specific expression is as follows:

[0057]

[0058] in: V th Indicates the amplitude of the equivalent voltage source. V g This represents the actual grid voltage amplitude. Z ft This represents the short-circuit impedance at PCC. Z g This represents the actual grid impedance. d This represents the phase difference between the internal potential of the energy storage converter and the grid voltage vector. i paj This indicates the phase jump value of the equivalent voltage source caused by the combined fault.

[0059] (2) Adaptive current limiting strategy and parameter design.

[0060] The adaptive virtual impedance current limiting strategy feeds forward the virtual impedance in the voltage loop. Z v =R v +jX v The voltage drop term caused by the fault depends on the real-time fault depth and the degree of overcurrent.

[0061] Transient modulation coefficient of virtual impedance K prt Designed based on the most severe fault conditions to ensure that the peak current in the first cycle is reliably limited, with the following specific requirements:

[0062]

[0063] in: Eref Internal potential of the energy storage converter E The amplitude is the reference value of the voltage control loop. s The reactance-resistance ratio represents the virtual impedance. I lim This indicates the current limiting modulus value set by the ring current limiter. R f This represents the total resistance from the PCC to the power grid in the main circuit. X f This represents the total reactance from PCC to the power grid in the main circuit. Figure 2 Showing transient modulation coefficients K prt Regarding the impact of transient peak current, the green area in the figure represents the safe region where the current limit is not exceeded, and the area above the red dashed line represents the overcurrent region. K prt When the current is 0.5, the system has a first-cycle peak current of 1.3 pu, exceeding the current limit; when K prt When =3, the system has a first-cycle peak current of 0.85 pu, which is within the safe range; when K prt When the current is 0.8, the system has the same peak current in the first cycle as the current limiting value.

[0064] steady-state modulation coefficient of virtual impedance K prs Based on the target damping ratio x tar The design ensures stable recovery after fault clearing, and the specific expression is as follows:

[0065]

[0066] in: oh n Indicates the rated angular velocity. J This represents the equivalent inertia of the virtual synchronous machine control loop. D p This represents the equivalent damping of the virtual synchronous machine control loop.

[0067] Reactance-resistivity ratio of virtual impedance s It is set to a constant greater than 1, so that the injection impedance is inductively dominant, thereby maintaining a certain power angle recovery capability while limiting current.

[0068] (3) Analysis of the instability mechanism caused by the current limiting strategy.

[0069] The combined effects of fault conditions and current limiting strategies significantly alter the power output characteristics of the converter, causing crucial changes to the direction of power angle shift and the acceleration / deceleration area, and further contributing to differences in the transient stability of grid-type converters. At this point, the expression for the converter's output power is as follows:

[0070]

[0071] in: This represents the total impedance phase angle of the Thevenin equivalent model under the current-limiting strategy after a fault, i.e. , Z th The impedance is the equivalent voltage source.

[0072] To fully elucidate the mechanism of the current limiting strategy under different combined faults, Table 1 sets up different fault scenarios, corresponding to different voltage amplitudes and phase jumps. Simultaneously, based on the above equations, the power angle characteristics of the converter were analyzed, such as... Figure 3 As shown: In Figure 3 In (a), the short-circuit impedance is set to be much greater than the resistance, exhibiting inductive dominance. At this point, approximately 40% voltage drop occurs, but the phase transition is close to 0. The system trajectory moves from the stable operating point (SEP) a to b at the instant the fault occurs; if the fault originates from... c If one location is cleared, the system location will change to [location]. d 1. And move further along the yellow fault-failure characteristics. At this point, the system has sufficient deceleration area to continue along the purple dashed line to recover stability; if the fault originates from... c If two locations are cleared, the system location will change to [location]. d 1. The system continues to move along the yellow characteristic following the fault, while still accelerating, its trajectory changing along the green dashed line, ultimately leading to synchronization instability. Figure 3 In scenario (b), the short-circuit impedance is set such that the reactance is much smaller than the resistance, exhibiting a resistive dominance. This results in a voltage drop of approximately 9% and a phase jump of -22°. Under this fault scenario, the system's power angle characteristic curve undergoes a phase shift, leading to a new stable operating point (SEPL) and an unstable operating point (UEPL). The system's trajectory jumps from stable operating point a to b at the instant the fault occurs, and due to inertia, the power angle continues to move in the negative direction. If the fault originates from... c If one location is cleared (without crossing the UEPL), the system location will jump to [location]. d 1. Move along the purple dotted line to return to the original stable operating point a; if the fault originates from... c If two points are cleared (beyond UEPL), the system location will jump to... d 2. The system moves further along the yellow fault characteristics. At this point, the system has sufficient acceleration area, and the trajectory changes along the green dashed line, eventually leading to synchronization instability.

[0073] Table 1

[0074]

[0075] Step 2: Dynamic perception of work angle and design of active stabilization intervention strategy.

[0076] (1) Design of power compensation terms.

[0077] Power compensation item P adj It is generated by the grid connection point voltage and the virtual impedance, and its specific expression is:

[0078]

[0079] in: V pccq The q-axis component represents the voltage at the point of common coupling. R v This represents the virtual resistance generated by the virtual impedance loop. The control objective of zero on the q-axis of the voltage loop determines that this vector control is oriented along the potential d-axis. R v This reflects the voltage drop and the degree of overcurrent. Both of these indicate the degree of operating point shift during the transient state of the system. Therefore, the power compensation term is characterized by the product of the two.

[0080] (2) Triggering decision-making logic.

[0081] During the continuous operation of the current limiting strategy, the rate of change of the system power angle is calculated and monitored in real time. Based on preset decision logic, the generated power compensation term is injected into a designated node in the virtual synchronous machine control loop. This preset logic refers to monitoring the rate of change of the power angle d... d / d t The power compensation term is determined based on the sign. P adj The direction of action and the point of action of the system are governed by the following rules:

[0082] 1. If d d / d t If the value is less than 0, the system is determined to lack acceleration torque, and the control... P adj The active power reference input terminal of the virtual synchronous control loop is injected with positive polarity, and the power input reference is dynamically adjusted at the power balance point.

[0083] 2. If d d / d t If the value is greater than 0, the system is determined to lack damping torque, and the control... P adj The frequency feedforward of the virtual synchronous control loop is injected with negative polarity to correct the internal generation frequency of the virtual synchronous generator in real time during the angular velocity synthesis stage.

[0084] (3) Mathematical model of transient stabilization method.

[0085] The impact of the aforementioned power compensation term on the transient stability of the system is characterized by the second-order equation of motion for the power angle, specifically expressed as follows:

[0086]

[0087] in: P ref This represents the reference power value for the virtual synchronous machine control loop. P e This represents the active power output by the converter to the power grid. α This indicates the position enable signal for the active power reference terminal. β This indicates the position enable signal for the frequency feedforward. c This represents the polarity adaptive coefficient of the power compensation term.

[0088] The position enable signal and polarity adaptive coefficient of the aforementioned power compensation term determine the polarity and position injected into the synchronization link, such as... Figure 4 As shown, the specific mathematical expression is as follows:

[0089]

[0090] The transient stabilization method designed in step two is as follows: Figure 5 As shown, the entire process demonstrates a complete transient stabilization method, from dynamic perception of power angle to generation of power compensation terms, and then to preset logical decision-making behavior.

[0091] Next, we verified the effectiveness of the transient stabilization method of this invention based on the Typhoon HIL 602+ hardware-in-the-loop simulation platform. The waveform is shown below. Figure 6 As shown, Figure 6 (a) shows the transient response waveform of the grid-type converter without the stabilization strategy proposed in this invention. During the fault duration, the power angle... d Continuously increasing, power P e This also leads to large-scale fluctuations, and at the same time, large external disturbances cause the system to experience instantaneous and extremely large overcurrents, exceeding the current limiting range. After the fault is cleared, the system has a long recovery period, during which the converter power angle... d Continue to increase, outputting greater power. P e This seriously jeopardizes the safe operation of power electronic energy storage and the synchronous stability of the power system. Figure 6 (b) The transient stabilization strategy of the present invention was verified in multiple scenarios and over long periods of time. During the multiple fault durations of up to 1 second, the power angle... dAll showed stable convergence without sustained divergence, and the power... P e It also stabilizes, and simultaneously, during the instant of the fault and during the fault recovery period, the converter's output current... I cdq None of them exceeded the current limit. V pcc This indicates the voltage at PCC.

[0092] The above verification in multiple combined fault scenarios fully and powerfully demonstrates that the transient stabilization method of the present invention, which takes into account the current limiting strategy, can simultaneously achieve overcurrent suppression and transient synchronous stability improvement, significantly enhancing the ride-through capability of grid-type converters under severe combined faults and the reliability of grid support.

[0093] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A transient stabilization method for grid-type energy storage considering combined fault and current-limiting strategies, characterized in that, Includes the following steps: (1) For grid-connected energy storage systems, when a combined fault including voltage drop and phase angle jump occurs at the PCC, the fault characteristics are detected in real time and the current limiting strategy based on AVI is immediately triggered. The compensation voltage is generated by adjusting the resistive and inductive components of the virtual impedance online to correct the voltage reference vector of the voltage loop, thereby limiting the amplitude of the output current of the energy storage converter in the system to within the preset safety threshold. (2) During the continuous operation of the current limiting strategy, the rate of change of the system power angle is monitored in real time, a power compensation term reflecting the transient offset characteristics is constructed, and the power compensation term is applied to the reference power input terminal or frequency feedforward terminal of the virtual synchronous machine control loop according to the preset decision logic to provide compensatory synchronous torque, thereby enhancing and maintaining the transient synchronous stability of the system; the decision logic is as follows: When d δ / d t When <0, it is determined that the system lacks acceleration torque, and the power compensation term is injected into the reference power input terminal of the virtual synchronous machine control loop with positive polarity; When d δ / d t When the value is greater than 0, it is determined that the system lacks damping torque, and the power compensation term is injected into the frequency feedforward terminal of the virtual synchronous machine control loop with negative polarity. in: δ This represents the phase difference between the internal potential of the energy storage converter and the grid voltage vector. t Indicates time.

2. The transient stabilization method for grid-type energy storage considering joint fault and current limiting strategies according to claim 1, characterized in that: The combined fault in step (1) is characterized by an equivalent voltage source in the Thevenin equivalent model, whose voltage vector is represented as follows: Its amplitude is V th The phase angle is paj - δ The specific expression is as follows: in: V g The voltage amplitude of the power grid. Z g For grid impedance, Z ft The short-circuit impedance at PCC is... This indicates the impedance phase angle. θ paj This indicates the phase jump value of the equivalent voltage source caused by the combined fault. δ This represents the phase difference between the internal potential of the energy storage converter and the grid voltage vector.

3. The transient stabilization method for grid-type energy storage considering combined fault and current limiting strategies according to claim 2, characterized in that, The current limiting strategy in step (1) corrects the voltage reference vector of the voltage loop using the following expression: in: E and E' These are the voltage reference vectors before and after correction, respectively. V z To compensate for voltage, I c This is the output current of the energy storage converter when the ring current limiter is triggered. Z v The impedance introduced by AVI in the equivalent model. j The imaginary unit, R vt For adaptive transient virtual resistance, X vt For adaptive transient virtual reactance, R vs For adaptive steady-state virtual resistance, X vs For adaptive steady-state virtual reactance, K prt These are the transient adaptive coefficients. K prs For steady-state adaptive coefficients, σ The reactance-resistance ratio of the virtual impedance, Δ V This represents the voltage drop depth at PCC. I th The trigger threshold of the steady-state virtual impedance and I th =0.9 I lim , I lim This is the current limiting value for the ring current limiter.

4. The transient stabilization method for grid-type energy storage considering combined fault and current limiting strategies according to claim 3, characterized in that, The transient adaptive coefficient K prt The calculation expression is as follows: in: R f This represents the total resistance from PCC to the power grid. X f This represents the total reactance from PCC to the power grid. E ref This represents the amplitude of the internal potential of the energy storage converter.

5. The transient stabilization method for grid-type energy storage considering combined fault and current limiting strategies according to claim 3, characterized in that, The output current I c The calculation expression is as follows: in: Z th The impedance of the equivalent voltage source. Indicates amplitude V th Phase angle is paj - δ voltage vector, R e This refers to the equivalent resistance introduced into the equivalent model when the ring current limiter is triggered. impedance Z th The phase angle.

6. The transient stabilization method for grid-type energy storage considering combined fault and current limiting strategies according to claim 5, characterized in that, The steady-state adaptive coefficient K prs The calculation expression is as follows: in: ξ tar Indicates the target damping ratio. ω n Indicates the rated angular velocity of the power grid. J This represents the equivalent inertia of the virtual synchronous machine control loop. D p This represents the equivalent damping of the virtual synchronous machine control loop. P e This refers to the output active power of the energy storage converter.

7. The transient stabilization method for grid-type energy storage considering combined fault and current limiting strategies according to claim 6, characterized in that, The output active power P e The calculation expression is as follows: in: This represents the total impedance phase angle of the equivalent model under the current limiting strategy after a fault. .

8. The transient stabilization method for grid-type energy storage considering joint fault and current limiting strategies according to claim 3, characterized in that: The reactance-resistivity ratio of the virtual impedance σ The value is set to a constant greater than 1, so that the injection impedance is inductively dominant, thereby maintaining a certain power angle recovery capability while limiting current.

9. The transient stabilization method for grid-type energy storage considering combined fault and current limiting strategies according to claim 1, characterized in that, The calculation expression for the power compensation term in step (2) is as follows: in: P adj For power compensation, V pccq This represents the q-axis voltage component at PCC. R v Represents the virtual resistance of AVI and R v = R vt + R vs , R vt For adaptive transient virtual resistance, R vs This is an adaptive steady-state virtual resistance.

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