Transient state performance improvement control method and system for network construction type energy storage converter

Abstract

The invention relates to the technical field of energy storage converters, and provides a transient performance improvement control method and system for a network construction type energy storage converter, and the method comprises the steps: employing an active reference adjustment coefficient to adjust an active power reference value for active power, calculating the deviation between the active power and the active power reference value, and obtaining a phase angle through an active ring; for reactive power, the deviation between the reactive power and a reactive power reference value is calculated, and internal potential is obtained through a reactive ring; by controlling the on-off of the first switch, the internal potential is used as the input of the impact current suppression ring during normal operation, and the voltage regulation parameter is used as the input of the impact current suppression ring when a power grid has a fault; and the impulse current suppression ring obtains the output of the impulse current ring by controlling the on-off of the second switch and controlling the input or exit of the impulse current suppression impedance, obtains a modulation signal through the voltage ring and the current ring, and generates a driving pulse of each power switch device. And the transient performance, the robustness and the engineering applicability are obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of energy storage converter technology, and particularly relates to a method and system for improving the transient performance of a grid-type energy storage converter. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Under conditions of high-proportion renewable energy grid integration, the power system gradually exhibits weak grid characteristics due to a significant increase in equivalent grid impedance. Traditional energy storage converters are prone to instability and grid disconnection in this context. In contrast, grid-connected energy storage converters, with their active voltage and frequency support capabilities, can significantly enhance grid stability and robustness, and are considered one of the key technologies for new power systems with high renewable energy proportions. However, when a voltage dip fault occurs in the grid, the potential difference between the grid-connected converter port and the fault point increases significantly, easily leading to inrush currents far exceeding the rated value, and limiting output power. This is accompanied by synchronous instability, seriously threatening the safe and stable operation of grid-connected energy storage converters. Therefore, how to simultaneously achieve synchronous stability and effective current limiting of grid-connected energy storage converters under low-voltage fault conditions is crucial to ensuring their reliable operation.

[0004] To address the phenomenon of inrush current during faults, the academic paper "An Inrush Current Limiting Method for Grid-Connected Converters Considering Grid Voltage Disturbances," published in the *IEEE Journal of Emerging and Selected Topics in Power Electronics*, Volume 10, Issue 2, 2022, proposes a current limiting method based on pulse width modulation (PWM) drive signals. This strategy requires no adjustment to the internal structure of the controller. Its working principle is to compare the output current amplitude with a preset threshold: when the current exceeds the preset upper threshold, all PWM drive signals are immediately shut down, turning off all switches; only when the current drops to the lower threshold does the PWM modulation output resume. However, because this method lacks a necessary exit mechanism, it is prone to periodic PWM shutdown-recovery oscillations under fault conditions in grid-connected converters, leading to deterioration of the system's dynamic response characteristics and the introduction of significant current harmonics.

[0005] Regarding the suppression of steady-state overcurrent during faults, the academic paper "Current-Constrained Power-Angle Characterization Method for Transient Stability Analysis of Grid-Forming Voltage Source Converters," published in *IEEE Transactions on Energy Conversion*, Volume 38, Issue 2, 2023, introduces a ring current limiter strategy. This strategy effectively suppresses fault overcurrent through a limiting mechanism, offering advantages such as simple structure and ease of engineering implementation. However, the inherent strong nonlinearity of this current limiter significantly alters the equivalent dynamic behavior of the grid converter, increasing the complexity of transient stability analysis and limiting the ability to accurately characterize stability under fault conditions. The academic paper "Virtual Impedance Current Limiting for Inverters in Microgrids With Synchronous Generators," published in *IEEE Transactions on Industry Applications*, Volume 51, Issue 2, 2015, proposes an adaptive virtual impedance strategy. This strategy dynamically adjusts the impedance value by real-time evaluation of the fault current's exceedance level, effectively suppressing transient current. However, the introduction of the virtual impedance method further reduces the output power characteristics. (The last sentence appears to be incomplete and possibly refers to a separate topic.) The academic paper "Grid-Forming Vector Current Control" published in Volume 37, Issue 11 of Power Electronics in 2022 switched the grid-forming control strategy to grid-following control during a fault to directly limit the converter output current. Although it can achieve current suppression to a certain extent, it generally does not fully consider the inherent voltage source characteristics and synchronization mechanism of grid-forming control, thus disrupting its original grid-forming behavior during a fault and causing a significant deviation in support capability and dynamic characteristics.

[0006] Regarding improving synchronization stability, the academic paper "A Robust Low-Voltage-Ride-Through Strategy for Grid-Forming Converters Based on Reactive Power Synchronization," published in IEEE Transactions on Power Electronics, Volume 38, Issue 1, 2023, reshapes the inherent power angle characteristics of the grid-forming converter by introducing additional control loops into the traditional grid control framework, thereby enhancing the transient synchronization stability of the system during grid disturbances. Furthermore, the academic paper "Transient Stability-Enhancing Method for Grid-Forming Inverters Under Current Limiting," published in IEEE Transactions on Power Electronics, Volume 40, Issue 5, 2025, proposes a virtual power control method. This method constructs virtual power variables to replace real active power in dynamic power angle adjustment, enabling the maintenance of a stable operating point without reducing the active power reference value. Although this method has achieved some success in maintaining stability, its virtual quantities do not reflect the actual output power characteristics of the converter, leading to a deviation between the control objective and physical behavior, thus limiting its applicability in complex grid environments.

[0007] In summary, while existing studies have proposed methods such as power angle curve reshaping, PWM forced current limiting, virtual impedance, and voltage droop adjustment, these strategies still have the following shortcomings: First, most methods fail to coordinate current limiting with grid-connected behavior, suppressing fault current while disrupting the voltage source characteristics of the grid-connected converter, leading to deterioration in dynamic performance. Second, existing virtual impedance methods typically operate continuously throughout the fault, making it difficult to avoid negatively impacting transient processes, synchronization dynamics, and voltage support capabilities. Third, some strategies rely on control mode switching or multivariable coupling regulation, resulting in complex control structures. Therefore, improving the transient performance of grid-connected energy storage converters under weak grid and fault conditions still faces significant challenges. Summary of the Invention

[0008] To address the technical problems mentioned above, this invention provides a transient performance enhancement control method and system for grid-connected energy storage converters. Through the synergistic effect of power reference dynamic adjustment, inrush current suppression impedance, and voltage adaptive adjustment, the synchronous stability maintenance and current limiting control of the grid-connected energy storage converter during grid fault cycles are achieved, significantly improving transient performance, robustness, and engineering applicability.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of the present invention provides a method for improving the transient performance control of a grid-type energy storage converter, comprising: Obtain the output voltage and output current of the grid-type energy storage converter, and calculate the active power and reactive power. For active power, the active power reference value is adjusted using an active power reference adjustment coefficient, and the deviation between the active power and the active power reference value is calculated. The phase angle is obtained through the active power loop. For reactive power, the deviation from the reactive power reference value is calculated, and the internal potential is obtained through the reactive power loop. By controlling the opening and closing of the first switch, the internal potential is used as the input of the inrush current suppression loop during normal operation, and the voltage regulation parameter is used as the input of the inrush current suppression loop during grid faults. The inrush current suppression loop controls the connection or disconnection of the inrush current suppression impedance by controlling the opening and closing of the second switch, thus obtaining the output of the inrush current loop. Based on the output of the impulse current loop, the modulation signal is obtained through the voltage loop and the current loop; Based on the modulation signal and phase angle, drive pulses for each power switching device are generated through coordinate transformation and pulse width modulation.

[0010] Furthermore, the adjustment of the active power reference value using the active power reference adjustment coefficient is expressed as: P ref- P adj , where P adj P is the active power reference adjustment coefficient. ref This is a reference value for active power.

[0011] Furthermore, during normal operation, the second switch is in the closed state, and the inrush current suppression impedance is short-circuited.

[0012] Furthermore, in the event of a power grid fault, the second switch is opened, allowing the inrush current suppression impedance to participate in the circuit operation. After the second switch is closed and held for a set time interval, the second switch is opened, causing the inrush current suppression impedance to be short-circuited.

[0013] Furthermore, the active power reference adjustment coefficient is Among them, V n V represents the rated voltage. o It represents the voltage amplitude at the grid connection point.

[0014] Furthermore, the voltage regulation parameter is as follows: ; where k v The adjustment coefficient is used; the intermediate variables m1 and m2 are respectively: , ;I lim V is the desired current limiting value. o X represents the voltage amplitude at the grid connection point. P represents the equivalent total resistance. o This refers to active power.

[0015] Furthermore, the surge current suppression impedance is Where j0 represents the inductive reactance in the impulse current suppression impedance is 0, and I lim The desired current limiting value, R ∑ The equivalent total impedance is represented by E, the internal potential is X. This represents the equivalent total resistance.

[0016] A second aspect of the present invention provides a transient performance enhancement control system for a grid-type energy storage converter, comprising: The power calculation module is configured to: acquire the output voltage and output current of the grid-type energy storage converter, and obtain the active power and reactive power through power calculation; The power control module is configured as follows: for active power, after adjusting the active power reference value using an active power reference adjustment coefficient, the deviation between the active power and the active power reference value is calculated, and the phase angle is obtained through the active power loop; for reactive power, the deviation from the reactive power reference value is calculated, and the internal potential is obtained through the reactive power loop; by controlling the on / off state of the first switch, the internal potential is used as the input of the inrush current suppression loop during normal operation, and the voltage regulation parameter is used as the input of the inrush current suppression loop during grid faults; the inrush current suppression loop controls the on / off state of the second switch to control the engagement or disengagement of the inrush current suppression impedance, thereby obtaining the inrush current loop output. The voltage control and current control module is configured to obtain a modulation signal based on the output of the inrush current loop, through the voltage loop and the current loop; The pulse width modulation module is configured to generate drive pulses for each power switching device based on the modulation signal and phase angle, through coordinate transformation and pulse width modulation.

[0017] A third aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for improving the transient performance of a grid-type energy storage converter.

[0018] A fourth aspect of the present invention provides a computer device including a computer-readable storage medium, a processor, and a computer program stored on the computer-readable storage medium and executable on the processor, wherein the processor executes the program to implement the steps of the above-described method for improving the transient performance of a grid-type energy storage converter.

[0019] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves synchronous stability maintenance and current limiting control of grid-type energy storage converters during grid fault cycles through the synergistic effect of power reference dynamic adjustment, inrush current suppression impedance, and voltage adaptive adjustment, significantly improving transient performance, robustness, and engineering applicability.

[0020] To ensure a stable equilibrium point after a fault occurs, this invention introduces an active power reference adaptive adjustment mechanism. This mechanism actively adjusts the power reference based on the output voltage after the fault, so that the power angle curve has a convergent stable operating point, thereby significantly improving the synchronization stability margin and avoiding synchronization instability or grid disconnection caused by power angle instability.

[0021] This invention proposes a virtual impedance method for suppressing inrush current in response to faults, enabling the converter to quickly suppress inrush current.

[0022] To address overcurrent in steady-state fault conditions, this invention utilizes a bypass reactive power control loop and introduces a voltage regulation coefficient to achieve continuous control over the output voltage command. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 This is a partial flowchart of a transient performance improvement control method for a grid-type energy storage converter according to Embodiment 1 of the present invention; Figure 2 This is an overall flowchart of a transient performance improvement control method for a grid-type energy storage converter according to Embodiment 1 of the present invention; Figure 3 This is a control logic diagram of switches S1 and S2 according to Embodiment 1 of the present invention; Figure 4 This is an experimental waveform diagram of Embodiment 1 of the present invention without any strategy; Figure 5 Under the control method of Embodiment 1 of the present invention and V g Experimental waveform diagram of 0.2 pu; Figure 6 Under the control method of Embodiment 1 of the present invention and V g Experimental waveform diagram of 0.4 pu; Figure 7 This is a schematic diagram of the structure of a computer device according to Embodiment 4 of the present invention. Detailed Implementation

[0025] 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.

[0026] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] Example 1 This embodiment provides a method for improving the transient performance control of a grid-type energy storage converter.

[0028] This embodiment provides a transient performance enhancement control method for a grid-type energy storage converter, which can effectively suppress fault overcurrent under grid fault conditions while maintaining synchronization stability, thereby ensuring the safe and reliable operation of the grid-type energy storage converter under extreme conditions.

[0029] This embodiment provides a transient performance enhancement control method for a grid-type energy storage converter. Through coordinated design of power angle characteristic reshaping, inrush current suppression, and fault steady-state overcurrent constraints, it can balance current limiting control and transient synchronization stability assurance in the grid-type energy storage converter. By dynamically adjusting the active power reference value in the grid-type control framework, a convergent stable equilibrium point can still be achieved under fault disturbances, thereby significantly improving power angle stability and avoiding synchronization instability caused by excessive power angle deviation. Furthermore, by introducing an inrush current suppression impedance method on the output side of the converter voltage loop, rapid suppression of inrush current is achieved. The system only participates in control for one power frequency cycle after the fault occurs and automatically exits after the suppression ends, so as to avoid the impact of the inrush current suppression impedance on the transient dynamic characteristics of the subsequent fault process, thus balancing inrush current suppression and dynamic performance maintenance. To suppress the overcurrent in the fault steady state, the system achieves adaptive adjustment of the converter voltage reference amplitude by bypassing the reactive power control loop and introducing a voltage regulation coefficient. On the one hand, it ensures that the converter has the necessary voltage support capability during the fault, and on the other hand, it effectively limits the fault steady-state overcurrent by appropriately adjusting the voltage command, avoiding the damage to the grid structure or the occurrence of harmonic and oscillation problems caused by traditional current limiting methods.

[0030] This embodiment provides a transient performance enhancement control method for a grid-type energy storage converter, such as... Figure 2 As shown, it includes the main power circuit, power calculation stage, power control, voltage control, current control, coordinate transformation, and pulse width modulation (PWM).

[0031] The DC side of the grid-connected energy storage converter is the energy storage battery V. DCThe output of the grid-connected energy storage converter is filtered by inductor L. f Filter capacitor C f Connect to a common coupling point and through the grid impedance Z g Connect to the AC power grid.

[0032] This embodiment provides a transient performance enhancement control method for a grid-type energy storage converter, including: the output voltage v of the grid-type energy storage converter. o and output current i o First, the three-phase stationary coordinate system is mapped to the synchronous rotating coordinate system via Park transformation to obtain the steady-state quantized voltage and current components. Based on the electrical quantities in the synchronous rotating coordinate system, the active power P output by the grid-type energy storage converter can be accurately calculated through power calculation. o With reactive power Q o Subsequently, the power control loop outputs the equivalent internal potential amplitude E and phase angle θ according to the set power reference command. The voltage control loop uses virtual admittance control and outputs signal i. dref and i qref As the input of the current loop, the output of the current loop is a modulated signal in the dq coordinate system. After the inverse Park transformation, it is converted to the three-phase stationary coordinate system and finally triggered by PWM to generate drive pulses for each power switching device, so as to realize the on and off control of the switching device.

[0033] like Figure 1 As shown, Figure 2 The power control loop in the system can be divided into active loop and reactive loop.

[0034] Step 1: The active power loop uses the active power reference value P ref With active power P o The deviation between them is taken as input, via a process that includes the equivalent inertia Js and the damping coefficient D. p The swing equation 1 / (Js+D) p Dynamic adjustment is performed to output a virtual angular velocity ω, and the angular velocity deviation Δω=ω Integrating ω0 (ω0 is the rated angular velocity) (1 / s) generates the phase angle θ; where 1 / s represents the integral after the Laplace transform, and s represents the differential. When the disturbance causes P o Significant changes occurred while P ref When the active power deviation remains constant, it will drive the phase angle θ to continuously shift, potentially causing power angle instability. Therefore, a power reference adjustment strategy is introduced into the active power loop by introducing a power reference adjustment coefficient P at the input. adj The power reference is dynamically adjusted to enhance power angle stability.

[0035] Specifically, the active power adaptive adjustment strategy is as follows: Since grid faults cause a significant drop in voltage at the grid connection point, the active power output capability of the converter decreases accordingly. If the power reference value before the fault is maintained, it may lead to the disappearance of the stable operating point and trigger synchronous instability. Therefore, it is necessary to adaptively reduce the power reference value during fault periods to ensure an achievable steady-state operating point under grid fault conditions. During grid faults, the active power reference value is dynamically reduced based on the degree of voltage drop at the PCC point. The specific active power adjustment parameter P... adj It can be expressed by the following formula: (1); Among them, V n V represents the rated voltage. o Represents the voltage amplitude at the point of common coupling (PCC). V od and V oq These represent the components of the output voltage vector along the d-axis (direct axis) and q-axis (quadrature axis) in the dq coordinate system (rotated coordinate system), respectively. Figure 2 As shown, in the active power loop, the active power reference adjustment coefficient P adj As part of the active power loop input to reduce the power reference, the post-fault power reference is equivalent to P. ref -P adj When operating normally, V o and V n They are equal, at this time P adj P is 0 when a power grid fault occurs. adj As the output voltage drops more, the value increases accordingly, thereby proportionally lowering the active power reference value.

[0036] Step 2: The reactive power loop uses the reactive power reference value Q. ref With reactive power Q o The deviation between them is taken as input, and then processed by the reactive power droop coefficient D. q After adjustment, the output voltage amplitude deviation ΔE, when superimposed with the rated voltage amplitude E0, generates an internal potential E, which serves as the input signal for the inrush current loop.

[0037] Step 3: Under fault conditions, by bypassing the traditional reactive power loop, the voltage regulation parameter V is introduced. adj As the input of the inrush current loop, it effectively suppresses steady-state overcurrent during faults. An inrush current loop is embedded between the reactive power loop and the voltage loop, and the inrush current suppression impedance Z is used to achieve effective suppression. s The system can be put into operation or withdrawn to quickly suppress the initial inrush current of a fault, and its output signal can be further used as a reference signal for the voltage loop.

[0038] (1) Fault steady-state overcurrent limitation: such as Figure 1 As shown, in the reactive power loop, the first switch S1 is connected at point 1 during normal operation, and the output of the reactive power loop is the internal potential E. When a grid fault is detected, switch S1 performs a switching action, the reactive power control loop is bypassed, and the output signal is switched from the internal potential E to the voltage regulation parameter V. adj .

[0039] Among them, V adj The derivation process is as follows: After switch S1 performs the switching action, the output power expression of the grid-connected energy storage converter is: (2); Among them, V adj and V g These represent the converter voltage regulation value and the grid voltage amplitude, respectively. δ represents the converter's virtual power angle, defined as the angle θ of the active power loop output relative to the grid angle θ. g The difference, i.e., δ = θ - θ g ;X Represents the equivalent total resistance, i.e.: X =X v +X g ; where X v For the voltage loop equivalent virtual inductive reactance; X g This refers to the inductive reactance component of the power grid impedance.

[0040] From equation (2), the sine expression for the virtual work angle can be obtained as follows: (3); Furthermore, the expression for the amplitude of the output current of the grid-connected energy storage converter is as follows: (4); When fault current limiting occurs, I o =I lim I lim Given the desired current limiting value, the cosine expression of the virtual power angle can be obtained from equation (4) as follows: (5); V adj The analytical expression is further derived from equations (4) and (5): (6); Wherein, the adjustment coefficient k v The deviation caused by parameter substitution is compensated, thereby achieving effective correction and adaptive adjustment of the voltage regulation; m1 and m2 represent intermediate variables, and their corresponding expressions are: (7).

[0041] (2) Inrush current suppression strategy: The inrush current suppression circuit is connected to the inrush current suppression impedance Z through the second switch S2. s composition.

[0042] Under normal operating conditions, the second switch S2 is in the closed state, Z s The circuit is short-circuited to ensure that the stable equivalent output impedance of the grid-connected converter is not affected by additional factors. When a grid fault is detected, the control fast-trigger switch S2 is opened, causing the inrush current suppression impedance Z to be short-circuited. s It participates in circuit operation, serving as the output signal of the reactive power loop, and the output of the inrush current loop serves as the input reference signal v of the voltage loop. dqref (i.e. v) dref and v qref In the initial stage of a fault, the equivalent output impedance of the converter is effectively increased, thereby suppressing the inrush current in the early stage of the fault. Subsequently, after the time interval ts when switch S2 is closed, S2 is opened, causing the inrush suppression impedance to be short-circuited and removed from the control loop, so as to avoid its continued existence from having an adverse effect on the transient dynamic characteristics.

[0043] Among them, the impulse current suppression impedance Z s The calculation process is as follows: At the initial moment of the fault, a significant aperiodic component will be superimposed on the output current, forming a large-amplitude inrush current. Considering the most severe fault in the power grid, namely a short-circuit fault, the corresponding expression for the inrush current is: (8); in, R ∑ Represents the equivalent total impedance. w 0 indicates the rated angular frequency. t Indicates the time of failure. φ Represents the circuit impedance angle. α The initial phase is the phase angle at t=0, τ is the time constant for the decay of the free component, and C is the integration constant. The corresponding expression is: (9); Among them, I o (0) represents the initial current value, E f This indicates the internal voltage reference value after a fault. Design the impulse current suppression impedance, i.e., I, for the maximum impulse current. o (0)=0 and α–φ=3π / 2, therefore the impulse current reaches its maximum value I approximately half a fundamental cycle. oImax The corresponding expression is: (10); To accommodate the large time constant and simplify the control implementation, the inrush current suppression impedance Z...s Designed as a pure resistor, the corresponding expression is: (11); Where j0 indicates that the inductive reactance component in the impulse current suppression impedance is 0.

[0044] The logic of switches S1 and S2 is as follows: Figure 3 As shown, when the output voltage is lower than the threshold voltage (0.9 pu), a grid fault is identified, and switch S1 is triggered to switch states. At the same time, switch S2 opens. At this time, the reactive power control loop is bypassed, and the reactive power loop output is converted from the internal potential E to the voltage regulation parameter V. adj Meanwhile, the impulse current suppression impedance Z s Access; after switch S2 is opened for ts time, S2 closes and ts is short-circuited to eliminate the influence of this impedance on the transient stability of the grid converter during the fault process. Here, ts corresponds to the power frequency period, i.e., ts=1 / fs, where fs represents the power frequency, which is also the rated frequency, corresponding to 50Hz.

[0045] Step 4: Voltage loop with reference signal v dqref (including v) dref and v qref ) and actual output voltage v odq (including v) od and v oq The deviation between ) is used as input, via the equivalent virtual admittance 1 / (L v s+R v Adjustment, and via jω0L v Feedforward enables decoupling control, generating a reference signal i for the current loop. dqref (including i) dref and i qref ).

[0046] Step 5, Reference current i dqref With inductor current i Ldq (including i) Ld and i Lq The deviation is transmitted through the PI controller in the current loop. Similarly, through jω0L f Feedforward achieves decoupling and ultimately generates the modulation signal for the converter. .

[0047] Step 6: The current loop output is a modulated signal in the dq coordinate system. The phase angle θ obtained in step 1 is transformed into a three-phase stationary coordinate system after inverse Park transformation, and finally triggered by PWM to generate drive pulses for each power switching device, so as to realize the on and off control of the switching device.

[0048] Figure 4 , Figure 5 and Figure 6 The experimental waveforms of the control strategy in this embodiment are shown. It can be seen that, without any strategy, when the grid voltage drops to 0.2 pu, the output active power of the GFM converter oscillates significantly due to the lack of a stable operating point, ultimately leading to severe synchronization instability. Simultaneously, an overcurrent significantly exceeding the rated value occurs. In contrast, when the control strategy of this embodiment is adopted, synchronization stability is maintained when the grid voltage drops to 0.4 pu and 0.2 pu, and the fault current is suppressed to below the desired value.

[0049] To address the issues of synchronous instability, inrush current, and steady-state overcurrent that grid-connected energy storage converters are prone to under grid fault conditions, this embodiment proposes a comprehensive control strategy that addresses the entire fault process while balancing synchronous stability and overcurrent suppression. This strategy is based on the coordinated control of the grid-connected energy storage converter using dynamic power angle adjustment, inrush current suppression impedance, and adaptive voltage reference adjustment, in order to improve transient stability performance under fault conditions.

[0050] This embodiment provides a transient performance enhancement control method for a grid-connected energy storage converter. First, to ensure a stable equilibrium point after a fault, an active power reference adaptive adjustment mechanism is introduced. This mechanism actively adjusts the power reference based on the output voltage after the fault, ensuring the power angle curve has a convergent stable operating point, thus significantly improving the synchronization stability margin and preventing synchronization instability or grid disconnection caused by power angle instability. Second, to address the inrush current during a fault, a virtual impedance method for suppressing inrush current is proposed, enabling the converter to quickly suppress inrush current. Finally, to cope with overcurrent in the fault steady state, a bypass reactive power control loop is used, and a voltage regulation coefficient is introduced to achieve continuous controllability of the output voltage command. This ensures necessary voltage support during faults while reducing the voltage amplitude, allowing the steady-state current limit to naturally meet the current safety boundary, thus achieving a balance between voltage support and current limiting.

[0051] In summary, this embodiment achieves synchronous stability maintenance and current limiting control of the grid-type energy storage converter during grid fault cycles through the synergistic effect of power reference dynamic adjustment, inrush current suppression impedance, and voltage adaptive adjustment, significantly improving transient performance, robustness, and engineering applicability.

[0052] Example 2 This embodiment provides a transient performance enhancement control system for a grid-type energy storage converter, comprising: The power calculation module is configured to: acquire the output voltage and output current of the grid-type energy storage converter, and obtain the active power and reactive power through power calculation; The power control module is configured as follows: for active power, after adjusting the active power reference value using an active power reference adjustment coefficient, the deviation between the active power and the active power reference value is calculated, and the phase angle is obtained through the active power loop; for reactive power, the deviation from the reactive power reference value is calculated, and the internal potential is obtained through the reactive power loop; by controlling the on / off state of the first switch, the internal potential is used as the input of the inrush current suppression loop during normal operation, and the voltage regulation parameter is used as the input of the inrush current suppression loop during grid faults; the inrush current suppression loop controls the on / off state of the second switch to control the engagement or disengagement of the inrush current suppression impedance, thereby obtaining the inrush current loop output. The voltage control and current control module is configured to obtain a modulation signal based on the output of the inrush current loop, through the voltage loop and the current loop; The pulse width modulation module is configured to generate drive pulses for each power switching device based on the modulation signal and phase angle, through coordinate transformation and pulse width modulation.

[0053] It should be noted that each module in this embodiment corresponds one-to-one with each step in Embodiment 1, and their specific implementation processes are the same, so they will not be repeated here.

[0054] Example 3 This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the transient performance improvement control method for a grid-type energy storage converter as described in Embodiment 1 above.

[0055] Example 4 This embodiment provides a computer device, such as... Figure 7 As shown, the system includes a computer-readable storage medium 1003, a processor 1001, a communication interface 1002, and a computer program stored on the computer-readable storage medium 1003 and executable on the processor 1001. The processor 1001, communication interface 1002, and computer-readable storage medium 1003 can be connected via a bus or other means. The communication interface 1002 is used to receive and transmit data. When the processor 1001 executes the program, it implements the steps in the transient performance improvement control method for a grid-type energy storage converter as described in Embodiment 1 above.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the transient performance control of a grid-type energy storage converter, characterized in that, include: Obtain the output voltage and output current of the grid-type energy storage converter, and calculate the active power and reactive power. For active power, the active power reference value is adjusted using an active power reference adjustment coefficient, and the deviation between the active power and the active power reference value is calculated. The phase angle is obtained through the active power loop. For reactive power, the deviation from the reactive power reference value is calculated, and the internal potential is obtained through the reactive power loop. By controlling the opening and closing of the first switch, the internal potential is used as the input of the inrush current suppression loop during normal operation, and the voltage regulation parameter is used as the input of the inrush current suppression loop during grid faults. The inrush current suppression loop controls the connection or disconnection of the inrush current suppression impedance by controlling the opening and closing of the second switch, thus obtaining the output of the inrush current loop. Based on the output of the impulse current loop, the modulation signal is obtained through the voltage loop and the current loop; Based on the modulation signal and phase angle, drive pulses for each power switching device are generated through coordinate transformation and pulse width modulation.

2. The transient performance improvement control method for a grid-type energy storage converter as described in claim 1, characterized in that, The adjustment of the active power reference value using the active power reference adjustment coefficient is expressed as: P ref- P adj , where P adj P is the active power reference adjustment coefficient. ref This is a reference value for active power.

3. The transient performance improvement control method for a grid-type energy storage converter as described in claim 1, characterized in that, During normal operation, the second switch is in the closed state, and the inrush current suppression impedance is short-circuited.

4. The transient performance improvement control method for a grid-type energy storage converter as described in claim 1, characterized in that, In the event of a power grid fault, the second switch opens, allowing the inrush current suppression impedance to participate in the circuit operation. After the second switch is closed and held for a set time interval, the second switch opens, short-circuiting the inrush current suppression impedance.

5. The transient performance improvement control method for a grid-type energy storage converter as described in claim 1, characterized in that, The active power reference adjustment coefficient is ; Among them, V n V represents the rated voltage. o It represents the voltage amplitude at the grid connection point.

6. The transient performance improvement control method for a grid-type energy storage converter as described in claim 1, characterized in that, The voltage regulation parameters are as follows: ; where k v The adjustment coefficient is used; the intermediate variables m1 and m2 are respectively: , ;I lim V is the desired current limiting value. o X represents the voltage amplitude at the grid connection point. P represents the equivalent total resistance. o This refers to active power.

7. The transient performance improvement control method for a grid-type energy storage converter as described in claim 1, characterized in that, The surge current suppression impedance is Where j0 represents the inductive reactance in the impulse current suppression impedance is 0, and I lim The desired current limiting value, R ∑ The equivalent total impedance is represented by E, the internal potential is X. This represents the equivalent total resistance.

8. A transient performance enhancement control system for a grid-type energy storage converter, characterized in that, include: The power calculation module is configured to: acquire the output voltage and output current of the grid-type energy storage converter, and obtain the active power and reactive power through power calculation; The power control module is configured as follows: for active power, after adjusting the active power reference value using an active power reference adjustment coefficient, the deviation between the active power and the active power reference value is calculated, and the phase angle is obtained through the active power loop; for reactive power, the deviation from the reactive power reference value is calculated, and the internal potential is obtained through the reactive power loop; by controlling the on / off state of the first switch, the internal potential is used as the input of the inrush current suppression loop during normal operation, and the voltage regulation parameter is used as the input of the inrush current suppression loop during grid faults; the inrush current suppression loop controls the on / off state of the second switch to control the engagement or disengagement of the inrush current suppression impedance, thereby obtaining the inrush current loop output. The voltage control and current control module is configured to obtain a modulation signal based on the output of the inrush current loop, through the voltage loop and the current loop; The pulse width modulation module is configured to generate drive pulses for each power switching device based on the modulation signal and phase angle, through coordinate transformation and pulse width modulation.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the transient performance improvement control method for a grid-type energy storage converter as described in any one of claims 1-7.

10. A computer device comprising a computer-readable storage medium, a processor, and a computer program stored on the computer-readable storage medium and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the transient performance improvement control method for a grid-type energy storage converter as described in any one of claims 1-7.

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