Transient synchronization stabilizing method and device for hybrid system of power grid construction, computer device and medium

Abstract

The application relates to the technical field of power system stability control, in particular to a transient synchronous stability control method and device for a follow-grid hybrid system, computer equipment and a medium. The method comprises the following steps: when a follow-grid inverter and / or a grid-forming inverter in the follow-grid hybrid system is not in a steady-state operation state, a frequency deviation in an active power control loop of the grid-forming inverter is acquired; the frequency deviation is introduced into a reactive power control loop of the grid-forming inverter, and a reference voltage of the grid-forming inverter is determined based on the frequency deviation; and an output voltage of the grid-forming inverter is adjusted to match the reference voltage. By using the method, the interference of a phase-locked loop dynamic on a power control loop can be weakened, and the stability of the follow-grid hybrid system can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system stability control, in particular to a transient synchronization stability method and device for a hybrid system of grid-following and grid-forming, a computer device and a medium. BACKGROUND

[0002] With the rapid development of renewable energy, the deployment scale of inverters in the power grid has increased significantly. Grid-following inverters, as the main grid-connected interface of renewable energy, mainly synchronize with the grid through a phase-locked loop. However, in the case of a fault, the phase-locked loop faces the problem of losing synchronization and stability. Grid-forming inverters have the ability to actively support voltage and frequency, which can alleviate the loss of synchronization of grid-following inverters and improve the strength of the grid. Given the complementary nature of grid-following and grid-forming inverters, on the basis of grid-following renewable power generation, a grid-forming inverter-based energy storage system is configured, forming a hybrid system of grid-following and grid-forming inverters in parallel, which is considered to be the best grid-connected interface form for new energy stations and the only way for the development of renewable energy.

[0003] In recent years, there have been rich research results on the modeling and stability analysis of hybrid systems of grid-following and grid-forming. However, in the case of large disturbances to the inverters in the hybrid system of grid-following and grid-forming, existing small-signal linearization analysis methods often fail to capture key dynamic response information, making it difficult to accurately reflect the nonlinear dynamic characteristics and stability boundaries of the hybrid system of grid-following and grid-forming. Therefore, transient synchronization stability analysis and stabilization strategies under large disturbance conditions have become a current research hotspot.

[0004] Currently, the patent application CN120675200A mainly enables the grid-following inverter to track the phase of the grid-forming inverter through mode switching during a fault. However, this method fails to fully consider the limitations of the output capacity of the grid-following inverter, which may result in limited performance in actual applications and poor practicality. In addition, such a stabilization strategy may cause a shift in the steady-state equilibrium point after the fault is cleared, thereby affecting the steady-state operation performance of the system, and the change in steady-state performance does not meet the requirements of the IEEE1547-2018 standard. The patent application CN119696036A introduces an angle deviation to make the system transition to a stable state as soon as possible and reduce the range of the power grid affected by the fault. The patent application CN120301218A reduces the frequency deviation to adjust the inertia, thereby enhancing the transient synchronization capability of the grid-forming inverter and improving the overall transient synchronization stability of the system. However, the control effect of such a strategy is poor. The above existing technologies all have the problem of being unable to weaken the interference of the phase-locked loop dynamics on the power control loop. SUMMARY

[0005] Therefore, it is necessary to provide a transient synchronization stabilization method, apparatus, computer equipment, and medium for a grid-connected hybrid system that can weaken the dynamic interference of the phase-locked loop on the power control loop, in order to address the above-mentioned technical problems.

[0006] A transient synchronization stabilization method for a hybrid network system, the method comprising:

[0007] When the grid-connected inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in steady-state operation, the frequency deviation in the active power control loop of the grid-connected inverter is obtained.

[0008] The frequency deviation is introduced into the reactive power control loop of the grid inverter, and the reference voltage of the grid inverter is determined based on the frequency deviation.

[0009] Adjust the output voltage of the grid inverter to match the reference voltage;

[0010] The formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref -Q)+K(ω1-ω g ); where V 1ref V0 is the reference voltage of the grid inverter, and K is the transient voltage of the grid inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. ref Here, Q is the reactive power reference of the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power of the grid-connected inverter. g Let ω1-ω be the angular frequency of the power grid. g This represents the frequency deviation.

[0011] In this application, when the grid-connected inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in steady-state operation, the frequency deviation in the active power control loop of the grid-connected inverter is obtained, the frequency deviation is introduced into the reactive power control loop of the grid-connected inverter, and based on the frequency deviation, a reference voltage for the grid-connected inverter is determined. The output voltage of the grid-connected inverter is then adjusted to match the reference voltage. The formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref - Q)+K(ω1-ω g ); where V 1ref V0 is the reference voltage of the grid inverter, and K is the transient voltage of the grid inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. refHere, Q is the reactive power reference of the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power of the grid-connected inverter. g Let ω1-ω be the angular frequency of the power grid. g To account for the frequency deviation, when the frequency deviation is introduced into the reactive power control loop to adjust the output voltage, the cross-coupling effect between the active power control loop and the reactive power control loop in the grid-connected inverter is considered, thereby weakening or even decoupling the dynamic interference of the phase-locked loop on the power control loop, so that the grid-connected hybrid system remains stable.

[0012] In one embodiment, the process of determining whether the grid-connected inverter in the grid-connected hybrid system is in a steady-state operating state includes:

[0013] Determine the virtual potential reference and virtual potential of the grid-connected inverter;

[0014] When the virtual potential reference and the virtual potential are matched, it is determined that the grid-connected inverter is in a steady-state operation state;

[0015] When the virtual potential reference and the virtual potential do not match, it is determined that the grid-connected inverter is not in a steady-state operating state.

[0016] In this application, the grid-connected inverter is determined to be in steady-state operation when the virtual potential reference and the virtual potential match, and is determined not to be in steady-state operation when the virtual potential reference and the virtual potential do not match. This simplifies the process of determining whether the grid-connected inverter is in steady-state operation by defining the abstract "steady-state operation" with a quantifiable and measurable physical quantity. Furthermore, it enables the grid-connected hybrid system to make autonomous decisions, determining whether the grid-connected inverter is in steady-state operation without relying on external communication or complex global states.

[0017] In one embodiment, the virtual potential reference is calculated using the following formula: ;

[0018] The formula for calculating the virtual potential is: ;

[0019] Among them, V vref As a virtual potential reference, , , X g1 X is the transmission line impedance of the circuit where the grid inverter is located. g2 To determine the transmission line impedance of the circuit where the grid inverter is located, X g3 I2 is the transmission line impedance between the grid-connected hybrid system and the grid, I2 is the output current of the grid-connected inverter, and θ is the voltage across the grid. I It is the current injection angle of the grid inverter, Vv This is a virtual electromotive force, where V1 is the output voltage of the grid-connected inverter, δ2 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E, and δ1 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E. 21 =δ2-δ1.

[0020] In this application, by using the formula Calculate the virtual potential reference using the formula. Virtual potential allows for the consideration of the coupling relationship between the grid-connected inverter and the grid-connected inverter during potential calculations, thereby obtaining an accurate virtual potential and virtual potential reference.

[0021] In one embodiment, the formula for calculating the power angle δ2 between the grid connection point voltage of the grid-connected inverter and the grid voltage E is:

[0022] ;

[0023] V2 is the grid connection point voltage of the grid-connected inverter.

[0024] In this embodiment, the formula is used. Calculate the power angle δ2 between the grid connection point voltage of the grid-connected inverter and the grid voltage E. This allows for a comprehensive consideration of all factors affecting the power angle variation when calculating the power angle, thus obtaining an accurate power angle.

[0025] In one embodiment, the process of determining whether the grid inverter in the grid-connected hybrid system is in a steady-state operating state includes:

[0026] Determine the active power reference and output active power of the grid-connected inverter;

[0027] When the active power reference and the output active power are matched, it is determined that the grid inverter is in a steady-state operation state;

[0028] When the active power reference and the output active power do not match, it is determined that the grid inverter is not in a steady-state operation.

[0029] The formula for calculating the output active power is as follows:

[0030] ;

[0031] P represents the output active power, I1 represents the output current of the grid inverter, and E represents the grid voltage.

[0032] In this application, the grid-connected inverter is determined to be in steady-state operation when the active power reference and output active power are matched, and is determined to be not in steady-state operation when the active power reference and output active power are mismatched. This simplifies the process of determining whether the grid-connected inverter is in steady-state operation by defining the abstract "steady-state operation" with a quantifiable and measurable physical quantity. Furthermore, it enables the grid-connected hybrid system to make autonomous decisions, determining whether the grid-connected inverter is in steady-state operation without relying on external communication or complex global states.

[0033] In one embodiment, the formula for calculating the output current I1 of the grid inverter is:

[0034] ;

[0035] V1 is the output voltage of the grid-connected inverter, and I2 is the output current of the grid-connected inverter. , X g1 X is the transmission line impedance of the circuit where the grid inverter is located. g3 δ1 is the transmission line impedance between the grid-connected hybrid system and the grid; δ2 is the power angle between the grid-connected inverter's grid connection point voltage and the grid voltage E; δ1 is the power angle between the grid-connected inverter's grid connection point voltage and the grid voltage E; θ I It refers to the current injection angle of the grid inverter.

[0036] In this embodiment, the formula is used. Calculate the output current of the grid-connected inverter. This allows for a comprehensive consideration of all factors affecting the output current during the calculation, resulting in an accurate output current.

[0037] In one embodiment, before acquiring the frequency deviation in the active power control loop of the grid-connected inverter when the grid-connected inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in steady-state operation, the process includes:

[0038] Based on the current value of the grid voltage, detect whether there is a synchronization risk in the grid-connected hybrid system;

[0039] If there is no synchronization risk in the grid-connected hybrid system, switch the control mode of the grid-connected hybrid system to parallel mode, and determine whether the grid-connected inverter and the grid-connected inverter are in steady-state operation.

[0040] In the event of a synchronization risk in the hybrid mesh system, the microcontroller in the hybrid mesh system is controlled to reduce the strength of the EPWM signal.

[0041] In this embodiment, by controlling the microcontroller in the root-network hybrid system to reduce the strength of the EPWM signal when there is a synchronization risk in the root-network hybrid system, transient impacts can be actively suppressed, thereby protecting the root-network hybrid system from damage.

[0042] A transient synchronization and stabilization device for a hybrid network system, the device comprising:

[0043] The deviation acquisition module is used to acquire the frequency deviation in the active power control loop of the grid inverter when the grid inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in steady-state operation.

[0044] A reference voltage calculation module is used to introduce the frequency deviation into the reactive power control loop of the grid inverter, and determine the reference voltage of the grid inverter based on the frequency deviation.

[0045] A voltage regulation module is used to regulate the output voltage of the grid inverter to match the reference voltage; the formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref -Q)+K(ω1-ω g ); where V 1ref V0 is the reference voltage of the grid inverter, and K is the transient voltage of the grid inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. ref Here, Q is the reactive power reference of the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power of the grid-connected inverter. g Let ω1-ω be the angular frequency of the power grid. g This represents the frequency deviation.

[0046] A computer device includes a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the method described above.

[0047] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described method.

[0048] The beneficial effects of the aforementioned transient synchronization stabilization device, computer equipment, and medium in the grid-connected hybrid system are that, when the grid-connected inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in a steady-state operating state, the frequency deviation in the active power control loop of the grid-connected inverter is obtained, the frequency deviation is introduced into the reactive power control loop of the grid-connected inverter, and based on the frequency deviation, the reference voltage of the grid-connected inverter is determined. The output voltage of the grid-connected inverter is then adjusted to match the reference voltage. The formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref -Q)+K(ω1-ω g ); where V 1ref V0 is the reference voltage of the grid inverter, and K is the transient voltage of the grid inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. ref Here, Q is the reactive power reference of the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power of the grid-connected inverter. g Let ω1-ω be the angular frequency of the power grid. g To account for frequency deviation, when introducing frequency deviation into the reactive power control loop to adjust the output voltage, the cross-coupling effect between the active power control loop and the reactive power control loop in the grid-connected inverter should be considered, thereby weakening or even decoupling the dynamic interference of the phase-locked loop on the power control loop and improving the stability of the grid-connected hybrid system. Attached Figure Description

[0049] Figure 1 This is a diagram illustrating the application environment of a transient synchronization stabilization method for a hybrid network system in one embodiment.

[0050] Figure 2 This is a flowchart illustrating a transient synchronization stabilization method for a hybrid network system in one embodiment.

[0051] Figure 3 This is a schematic diagram of a transient interaction model in one embodiment;

[0052] Figure 4 This is a schematic diagram of a simplified circuit model of a hybrid network system in one embodiment;

[0053] Figure 5 This is a schematic diagram of a model considering the reactive power control loop of the grid inverter in a grid-connected hybrid system, as shown in one embodiment.

[0054] Figure 6 This is a schematic diagram illustrating the output voltage under different power grid conditions and proportional gain in one embodiment;

[0055] Figure 7This is a control block diagram for transient synchronization stabilization of a hybrid network system in one embodiment.

[0056] Figure 8 This is a flowchart of an interrupt subroutine in a hybrid network system according to one embodiment;

[0057] Figure 9 This is a flowchart of transient synchronization stabilization analysis in one embodiment;

[0058] Figure 10 Here is an overall flowchart of the transient synchronization stabilization method in one embodiment;

[0059] Figure 11 This is a schematic diagram of the experimental results in one embodiment;

[0060] Figure 12 This is a structural block diagram of a transient synchronization stabilization device for a hybrid network system in one embodiment. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0062] The transient synchronization stabilization method for a hybrid network system provided in this application can be applied to, for example, Figure 1 In the application environment shown, renewable energy generation equipment and energy storage systems are connected to a grid-connected hybrid system via a DC-DC boost converter. When the grid-connected inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in steady-state operation, the frequency deviation in the active power control loop of the grid-connected inverter is obtained; the frequency deviation is introduced into the reactive power control loop of the grid-connected inverter, and based on the frequency deviation, the reference voltage of the grid-connected inverter is determined; the output voltage of the grid-connected inverter is adjusted to match the reference voltage; the formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref - Q)+K(ω1-ω g ); where V 1ref V0 is the reference voltage of the grid-connected inverter, and K0 is the transient voltage of the grid-connected inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. ref Here, Q is the reactive power reference for the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power output of the grid-connected inverter. g Let ω1-ω be the angular frequency of the power grid. g This represents the frequency deviation. Where V1 is the output voltage of the grid-connected inverter, I1 is the output current of the grid-connected inverter, and L... f1It is the filter inductor of the grid inverter, C f It is the capacitor of the grid inverter, θ 1ref It is the power angle reference of the grid-connected inverter, θ 2ref It is the power angle reference of the grid inverter, P ref This is the active power reference of the grid-connected inverter, P is the output active power of the grid-connected inverter, and L1, L2, L... g It's an inductor, C dc1 It is the DC-side voltage regulator capacitor of the grid inverter, C dc2 It is the DC-side voltage regulator capacitor of the grid inverter, L f2 I2 is the equivalent filter inductance of the grid-connected inverter, I2 is the output current of the grid-connected inverter, and V2 is the grid connection point voltage of the grid-connected inverter. 2ref E is the grid voltage and serves as the current reference for the grid-connected inverter.

[0063] In one embodiment, such as Figure 2 As shown, a transient synchronization stabilization method for a hybrid network system is provided, which is then applied to... Figure 1 Taking a hybrid network system as an example, the following steps are included:

[0064] S202, when the grid-connected inverter and / or grid-connected inverter in the grid-connected hybrid system are not in steady-state operation, obtain the frequency deviation in the active power control loop of the grid-connected inverter;

[0065] The grid-connected hybrid system comprises both a grid-connected inverter and a grid-connected inverter. The grid-connected inverter uses virtual synchronous generator control, and its control law formula is as follows:

[0066] ;

[0067] Where J1 is the inertia of the grid inverter, and D p1 ω1 is the damping coefficient of the grid inverter, and ω is the angular frequency of the grid inverter. g P is the angular frequency of the power grid. ref It is the active power reference of the grid inverter, P is the output active power of the grid inverter, and t is time.

[0068] The grid-connected inverter is synchronized via a phase-locked loop. The control law formula for the grid-connected inverter is as follows:

[0069] ;

[0070] Where, k i It is a phase-locked loop integral, k p It is the proportional coefficient, ω2 is the angular frequency of the grid-connected inverter, and V 2q It is the difference between the output voltage and the reference voltage, where t is time.

[0071] Whether the inverter is in a steady-state operation refers to whether the operating parameters of the grid-connected inverter or the grid-connected inverter remain stable or whether the fluctuation exceeds a preset range. If the operating parameters of the grid-connected inverter remain stable or the fluctuation does not exceed the preset range, the grid-connected inverter is in a steady-state operation. If the operating parameters of the grid-connected inverter do not remain stable or the fluctuation exceeds the preset range, the grid-connected inverter is not in a steady-state operation. Similarly, if the operating parameters of the grid-connected inverter remain stable or the fluctuation does not exceed the preset range, the grid-connected inverter is in a steady-state operation. If the operating parameters of the grid-connected inverter do not remain stable or the fluctuation exceeds the preset range, the grid-connected inverter is not in a steady-state operation. Operating parameters include, but are not limited to, virtual potential, current, power, and frequency. Virtual potential is a virtual potential component dynamically generated internally by the grid-connected inverter / grid-connected inverter itself, used for power regulation.

[0072] The active power control loop is a closed-loop feedback control system used to precisely adjust the active power output of the grid inverter.

[0073] Frequency deviation is the difference between the angular frequency of the grid-connected inverter and the angular frequency of the power grid. The angular frequency of the grid-connected inverter is the angular frequency of the AC voltage it generates and outputs. The angular frequency of the power grid is the angular velocity of the periodic changes in AC voltage and current in the power system.

[0074] Specifically, when the grid-connected inverter is not in a steady-state operating state, or the grid-connected inverter is not in a steady-state operating state, or neither the grid-connected inverter nor the grid-connected inverter is in a steady-state operating state, the frequency deviation in the active power control loop of the grid-connected inverter is obtained.

[0075] S204 introduces the frequency deviation into the reactive power control loop of the grid inverter and determines the reference voltage of the grid inverter based on the frequency deviation.

[0076] The reactive power control loop of the grid-connected inverter regulates the reactive power output of the inverter to maintain voltage stability at the grid connection point and provide grid services such as reactive power support and voltage regulation. Introducing frequency deviation into the reactive power control loop of the grid-connected inverter essentially means taking the frequency deviation into account when calculating the reference voltage of the inverter, thus obtaining a reference voltage that accounts for the frequency deviation.

[0077] The reference voltage is the expected output voltage of the grid-connected inverter. The output voltage of the grid-connected inverter is the actual output voltage of the grid-connected inverter. The output voltage of the grid-connected inverter can also be called the grid connection point voltage at which the grid-connected inverter is connected to the grid.

[0078] S206, adjusts the output voltage of the grid inverter to match the reference voltage;

[0079] In this process, adjusting the output voltage of the grid-connected inverter to match the reference voltage means adjusting the output voltage to be consistent with the voltage parameters, or adjusting the difference between the output voltage and the reference voltage to be less than a preset voltage difference, thereby ensuring the stability of the grid-connected hybrid system.

[0080] The method for adjusting the output voltage of a grid-connected inverter to match the reference voltage includes: real-time acquisition of the output voltage of the grid-connected inverter; calculation of the difference between the output voltage and the reference voltage to obtain the voltage error; processing the voltage error through a proportional-integral controller to generate a reference current signal; comparing the reference current signal in the inner current loop with the output current of the grid-connected inverter to obtain the current error; and adjusting the switching signal of the grid-connected inverter based on the current error through the proportional-integral controller to control the output voltage and make the output voltage match the reference voltage.

[0081] The formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref - Q)+K(ω1-ω g ); where V 1ref V0 is the reference voltage of the grid-connected inverter, and K0 is the transient voltage of the grid-connected inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. ref Here, Q is the reactive power reference of the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power of the grid-connected inverter. g Let ω1-ω be the angular frequency of the power grid. g This represents the frequency deviation.

[0082] The beneficial effect of the aforementioned transient synchronization stabilization method for grid-connected hybrid systems is that, when the grid-connected inverter and / or the grid-connected inverter in the hybrid system are not in steady-state operation, the frequency deviation in the active power control loop of the grid-connected inverter is obtained, the frequency deviation is introduced into the reactive power control loop of the grid-connected inverter, and based on the frequency deviation, the reference voltage of the grid-connected inverter is determined. The output voltage of the grid-connected inverter is then adjusted to match the reference voltage. The formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref - Q)+K(ω1-ω g ); where V 1ref V0 is the reference voltage of the grid-connected inverter, and K0 is the transient voltage of the grid-connected inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. ref Here, Q is the reactive power reference of the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power of the grid-connected inverter. gLet ω1-ω be the angular frequency of the power grid. g To account for frequency deviation, when introducing frequency deviation into the reactive power control loop to adjust the output voltage, the cross-coupling effect between the active power control loop and the reactive power control loop in the grid-connected inverter should be considered, thereby weakening or even decoupling the dynamic interference of the phase-locked loop on the power control loop and improving the stability of the grid-connected hybrid system.

[0083] In one embodiment, the process of determining whether the grid-connected inverter in a grid-connected hybrid system is in a steady-state operating state includes:

[0084] Determine the virtual potential reference and virtual potential of the grid-connected inverter;

[0085] When using virtual potential reference and virtual potential matching, it is determined that the grid-connected inverter is in steady-state operation.

[0086] When the virtual potential reference and the virtual potential do not match, it is determined that the grid-connected inverter is not in a steady-state operating state.

[0087] The virtual potential reference is the desired virtual potential value determined by external commands or grid conditions. The virtual potential is a virtual potential component dynamically generated internally by the grid-connected inverter and used for power regulation.

[0088] Virtual potential reference and virtual potential matching means that the virtual potential reference and the virtual potential are consistent, or the difference between the virtual potential reference and the virtual potential is less than the preset potential difference.

[0089] A stable virtual potential reference and matching virtual potential indicate that the grid-connected inverter has not experienced significant disturbances, and the virtual potential remains stable. A mismatch between the virtual potential reference and virtual potential indicates that the grid-connected inverter has experienced significant disturbances, and the virtual potential fluctuates considerably.

[0090] In this embodiment, the grid-connected inverter is determined to be in a steady-state operating state when the virtual potential reference and the virtual potential match; conversely, it is determined to be not in a steady-state operating state when the virtual potential reference and the virtual potential do not match. This simplifies the determination process by defining the abstract "steady-state operating state" using a quantifiable and measurable physical quantity. Furthermore, it enables the grid-connected hybrid system to make autonomous decisions, determining whether the grid-connected inverter is in a steady-state operating state without relying on external communication or complex global states.

[0091] In one embodiment, the formula for calculating the virtual potential reference is: ;

[0092] The formula for calculating virtual potential is: ;

[0093] Among them, Vvref As a virtual potential reference, , , X g1 X is the transmission line impedance of the circuit where the grid inverter is located. g2 To determine the transmission line impedance of the circuit where the grid inverter is located, X g3 I2 is the transmission line impedance between the grid-connected hybrid system and the grid, I2 is the output current of the grid-connected inverter, and θ is the voltage across the grid. I It is the current injection angle of the grid inverter, V v This is a virtual electromotive force, where V1 is the output voltage of the grid-connected inverter, δ2 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E, and δ1 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E. 21 The value of δ is the power angle δ2 between the grid connection point voltage of the grid-connected inverter and the grid voltage E minus the power angle δ1 between the grid connection point voltage of the grid-connected inverter and the grid voltage E. 21 =δ2-δ1. It is the coupling term between the grid-connected inverter and the grid-connected inverter.

[0094] The difference V between the virtual potential reference and the virtual potential 2q =V vref -V v By substituting the formula for the difference between the virtual potential reference and the virtual potential into the control law formula of the grid-connected inverter, the transient second-order swing equation of the grid-connected inverter can be obtained, as follows:

[0095] ;

[0096] Where J2 is the inertia of the grid-connected inverter, and D... p2 It is the active power damping coefficient of the grid inverter, D p21 It is the coupling damping coefficient with the grid inverter, and t is time.

[0097] In this embodiment, the formula is used. Calculate the virtual potential reference using the formula. Virtual potential allows for the consideration of the coupling relationship between the grid-connected inverter and the grid-connected inverter during potential calculations, thereby obtaining an accurate virtual potential and virtual potential reference.

[0098] In one embodiment, the formula for calculating the power angle δ2 between the grid connection point voltage of the grid-connected inverter and the grid voltage E is:

[0099] .

[0100] in, =V2(cosδ2+jsinδ2), calculate the formula By corresponding the real and imaginary parts at both ends, we can obtain the first equation. Second Equation Given the known output voltage V1 of the grid-connected inverter, the power angle δ1 between the grid connection point voltage of the grid-connected inverter and the grid voltage E, the grid voltage E, the output current I2 of the grid-connected inverter, and the current injection angle θ of the grid-connected inverter... I Substituting these values ​​into the first and second equations, and solving them simultaneously, we can obtain the grid connection point voltage V2 of the grid-connected inverter and the power angle δ2 between the grid connection point voltage and the grid voltage E. The grid connection point voltage V2 of the grid-connected inverter is essentially also the output voltage of the grid-connected inverter.

[0101] In this embodiment, the formula is used. Calculate the power angle δ2 between the grid connection point voltage of the grid-connected inverter and the grid voltage E. This allows for a comprehensive consideration of all factors affecting the power angle variation when calculating the power angle, thus obtaining an accurate power angle.

[0102] In one embodiment, the process of determining whether the grid inverter in a grid-connected hybrid system is in a steady-state operating state includes:

[0103] Determine the active power reference and output active power of the grid-connected inverter;

[0104] When the active power reference and the output active power are matched, it is determined that the grid inverter is in steady-state operation.

[0105] When the active power reference and the output active power are mismatched, it is determined that the grid inverter is not in a steady-state operating state.

[0106] The formula for calculating the output active power is as follows:

[0107] ;

[0108] P represents the output active power, I1 represents the output current of the grid inverter, and E represents the grid voltage.

[0109] The active power reference is the expected active power output value of the grid-connected inverter. The output active power is the actual active power output of the grid-connected inverter.

[0110] The output current I1 of the grid inverter can be expressed by the formula The calculations show that V1 is the output voltage of the grid-connected inverter, δ1 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E, I2 is the output current of the grid-connected inverter, and θ is the voltage at which the inverter connects to the grid. I It is the current injection angle of the grid inverter, δ 12The difference between the power angle δ1 between the grid connection point voltage of the grid inverter and the grid voltage E and the power angle δ2 between the grid connection point voltage of the grid inverter and the grid voltage E is δ. 12 =δ1-δ2, , X g1 X is the transmission line impedance of the circuit where the grid inverter is located. g3 The impedance of transmission lines between the hybrid grid system and the power grid.

[0111] Active power reference and output active power matching means that the active power reference and output active power are the same, or the difference between the active power reference and output active power is less than the preset power difference. Active power reference and output active power mismatch means that the active power reference and output active power are not the same, or the difference between the active power reference and output active power is greater than the preset power difference.

[0112] Substituting the formula for calculating the output active power into the control law formula for the grid-connected inverter, we can obtain the second-order swing equation describing the transient process of the grid-connected inverter, as follows:

[0113] ;

[0114] Where J1 is the inertia of the grid inverter, and D p1 It is the damping coefficient of the grid inverter, P ref It is the active power reference of the grid inverter, and t is time.

[0115] Furthermore, combining the calculation formula for active power P... Virtual potential reference V vref and virtual potential V v The difference V between 2q =V vref -V v , and, Construct a transient interaction model for the hybrid network system. The transient interaction model is as follows: Figure 3 As shown. The terms marked in red are the coupling terms between the grid-connected inverter and the grid-connected inverter, and ΔP is the active power reference P of the grid-connected inverter. ref Subtracting the difference in active power P, Δω1 is the frequency deviation in the active power control loop of the grid-connected inverter, and Δω2 is the frequency deviation in the active power control loop of the grid-connected inverter. k i It is a phase-locked loop integral, k p It is the proportionality coefficient, δ 21 The value of δ2 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E, minus the power angle δ1 between the grid connection point voltage of the grid-connected inverter and the grid voltage E. s is the frequency domain differential operator. .

[0116] In this embodiment, the grid-connected inverter is determined to be in steady-state operation when the active power reference and output active power match, and is determined to be not in steady-state operation when the active power reference and output active power do not match. This simplifies the determination process by defining the abstract "steady-state operation" using a quantifiable and measurable physical quantity. Furthermore, it enables the grid-connected hybrid system to make autonomous decisions, determining whether the grid-connected inverter is in steady-state operation without relying on external communication or complex global states.

[0117] In one embodiment, the formula for calculating the output current I1 of the grid inverter is:

[0118] ;

[0119] V1 is the output voltage of the grid-connected inverter, and I2 is the output current of the grid-connected inverter. , X g1 X is the transmission line impedance of the circuit where the grid inverter is located. g3 δ1 is the transmission line impedance between the grid-connected hybrid system and the grid; δ2 is the power angle between the grid-connected inverter's grid connection point voltage and the grid voltage E; δ1 is the power angle between the grid-connected inverter's grid connection point voltage and the grid voltage E; θ I It refers to the current injection angle of the grid inverter.

[0120] Formula for calculating output current I1 This is a calculation formula under the following conditions: the DC bus voltage is constant, the power grid is an ideal single-machine infinite-large grid, the voltage and current controllers can achieve ideal tracking of the reference value, the grid-connected inverter and the grid-connected inverter model are ideal controlled voltage and current sources, and the line impedance is approximately inductive reactance. Under the above conditions, Figure 1 The simplified circuit model of the hybrid network system shown is as follows: Figure 4 As shown. V 1ref Q is the reference voltage for the grid-connected inverter. ref Here, Q is the reactive power reference for the grid-connected inverter, V1 is the output voltage of the grid-connected inverter, I1 is the output current of the grid-connected inverter, and L is the reactive power output of the grid-connected inverter. f1 It is the filter inductor of the grid inverter, θ 1ref It is the power angle reference of the grid-connected inverter, θ 2ref It is the power angle reference of the grid inverter, P ref It is the active power reference for the grid-connected inverter, L f2 I2 is the equivalent filter inductance of the grid-connected inverter, I2 is the output current of the grid-connected inverter, and V2 is the grid connection point voltage of the grid-connected inverter.2ref For the current reference of the grid-connected inverter, E is the grid voltage, X g1 X is the transmission line impedance of the circuit where the grid inverter is located. g2 To determine the transmission line impedance of the circuit where the grid inverter is located, X g3 The impedance of transmission lines between the hybrid grid system and the power grid.

[0121] In this embodiment, the formula is used. Calculate the output current of the grid-connected inverter. This allows for a comprehensive consideration of all factors affecting the output current during the calculation, resulting in an accurate output current.

[0122] In one embodiment, before acquiring the frequency deviation in the active power control loop of the grid-connected inverter when the grid-connected inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in steady-state operation, the process includes:

[0123] Based on the current value of the grid voltage, detect whether there is a synchronization risk in the grid-connected hybrid system;

[0124] If there is no synchronization risk in the grid-connected hybrid system, switch the control mode of the grid-connected hybrid system to parallel mode and determine whether the grid-connected inverter and the grid-connected inverter are in steady-state operation.

[0125] In situations where there is a synchronization risk in a hybrid mesh system, the microcontroller in the hybrid mesh system is controlled to reduce the strength of the EPWM signal.

[0126] Specifically, if the current grid voltage is 0, there is a synchronization risk in the grid-connected hybrid system. Furthermore, if the current grid voltage is detected to drop to 0, and neither the grid-connected inverter nor the grid-connected inverter can complete fault ride-through, then there is a synchronization risk in the grid-connected hybrid system. The inability of the grid-connected inverter and the grid-connected inverter to complete fault ride-through means that when a severe grid fault occurs, relying solely on the inverter's own control capabilities and hardware limitations, it is impossible to guarantee that it will not disconnect from the grid during the fault and will continue to provide necessary support to the grid, thus failing to meet the requirements of grid regulations.

[0127] Parallel mode is a mode in which grid-connected inverters and grid-connected inverters are simultaneously connected to the power grid and work together.

[0128] EPWM (Enhanced Pulse Width Modulation) signal is a high-precision, programmable digital PWM signal used in microcontrollers to drive inverter power switching devices. By setting the EPWM signal strength low, transient impacts are actively suppressed, thereby protecting the grid-connected hybrid system from damage.

[0129] In this embodiment, by controlling the microcontroller in the root-network hybrid system to reduce the strength of the EPWM signal when there is a synchronization risk in the root-network hybrid system, transient impacts can be actively suppressed, thereby protecting the root-network hybrid system from damage.

[0130] In power systems, grid-connected inverters are responsible for providing inertia and function as a type of synchronous generator. Therefore, in the transient synchronization stability analysis of hybrid grid-connected systems, grid-connected inverters occupy a relatively dominant position. For example... Figure 5 This model considers the reactive power control loop of the grid-connected inverter in a grid-connected hybrid system. Here, ΔQ is the reactive power reference Q of the grid-connected inverter. ref Subtracting the reactive power Q of the grid-connected inverter, s is the frequency domain differential operator. When considering the reactive power control loop of the grid-connected inverter, the voltage dynamics will change significantly. Figure 6 The output voltage is shown under different grid conditions and proportional gain, where E is the grid voltage, K is the proportional gain, and V is the voltage. 1ref V0 is the reference voltage of the grid-connected inverter, V1 is the transient voltage of the grid-connected inverter, V1 is the output voltage of the grid-connected inverter, and δ1 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E. The control block diagram for transient synchronization and stabilization of the grid-connected hybrid system is shown below. Figure 7 As shown. Where, △V1=K q (Q ref - Q), △V0=K(ω1-ω g ), △ω1=ω1-ω g s is the frequency domain differential operator.

[0131] In a specific application scenario, to improve the dynamic response capability and transient synchronization stability of the hybrid network system under large disturbance conditions, this application, combined with the software control structure, designs three core processes: interrupt subroutine logic, synchronization stability analysis process, and stabilization strategy execution mechanism, such as... Figure 8 , Figure 9 and Figure 10 As shown.

[0132] Figure 8The flowchart of the interrupt subroutine in the grid-connected hybrid system is shown. This program runs at a high frequency of 12.8kHz to achieve rapid sampling and processing of voltage and current. Specifically, the grid-connected hybrid system first samples the output voltage and output current. Then, a phase-locked loop (PLL) captures the phase of the grid voltage. After the synchronization power loop, if there is no synchronization risk, the control mode of the grid-connected hybrid system is switched to parallel mode according to the grid connection command from an external source or within the system. If a synchronization risk is detected, no grid connection command is sent; instead, the strength of the EPWM signal is reduced to actively suppress transient impacts, thereby protecting the system from damage. After switching to parallel mode, the operating status of the system is assessed in real time. Simultaneously, the sampled output voltage and output current are input to the current closed-loop control and compared with reference values. Based on the comparison result, a suitable SPWM (Sine Pulse Width Modulation) control signal is generated and output to the power drive layer for precise control.

[0133] Figure 9 This is a flowchart of the transient synchronization stabilization analysis. The process assumes the operation of a grid-connected hybrid system and dynamically monitors the stability of the grid-connected inverter and the grid-connected inverter. By constructing a state assessment mechanism centered on frequency, phase, and power synchronization deviation, it determines whether the grid-connected inverter and the grid-connected inverter in the grid-connected hybrid system are in a steady-state operating state. When it is detected that the grid-connected inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in a steady-state operating state, a stabilization strategy is triggered, actively intervening in the stability correction process. If the grid-connected hybrid system recovers to a steady-state operating state, the control process ends, and no further action is required.

[0134] Figure 10 This is the overall flowchart of the transient synchronization stabilization method. The transient synchronization stabilization strategy starts with system voltage and current sampling. It assesses the system's steady-state operation through a voltage feedforward channel. When the system is not in a steady-state state, the hybrid grid-connected system injects a frequency-dynamic feedforward signal into the reactive power control loop of the grid-connected inverter to improve the inverter's output voltage. This frequency feedforward channel works in conjunction with traditional control strategies, effectively improving voltage response dynamics without disrupting the overall control structure. This enhances the transient synchronization capability of the hybrid grid-connected system during fault occurrences, ultimately achieving the dual objectives of "improving voltage dynamics and maintaining transient stability."

[0135] This application uses three sets of experimental cases for comparative testing. Under the same grid fault conditions, Case A adopts a traditional droop control strategy, Case B adopts a communication-dependent stabilization strategy, and Case C adopts the transient synchronization stabilization method of the proposed grid-connected hybrid system. When the grid voltage drops to 0.6 pu, the experimental results of the above three sets of cases are as follows:Figure 11 As shown.

[0136] In Case A, taking the grid voltage drop to 0.6 pu as an example, under the traditional droop control strategy, due to power imbalance, the system angular frequency accelerates, the system phase angle continues to increase, causing instability in the parallel system. For example... Figure 11 As shown in part (a) of the document.

[0137] In Case B, taking the grid voltage drop to 0.6 pu as an example, the communication-dependent stabilization strategy introduces a communication-based stabilization strategy. Its core idea is to achieve coordinated control among inverters through information sharing. However, in practical engineering applications, communication links inevitably experience transmission delays, especially when facing sudden disturbances. In this case, due to the significant time lag between the fault occurrence and the stabilization strategy taking effect, the system has already crossed the critical stability boundary when the control strategy intervenes, missing the control window and causing the stabilization measures to fail. The system still exhibits obvious synchronous instability characteristics, such as... Figure 11 As shown in part (b) of the document.

[0138] In Case C, taking the grid voltage drop to 0.6 pu as an example, the hybrid grid system, upon detecting the voltage drop, does not rely on external communication. Instead, it directly injects the frequency deviation into the reactive power control loop as a voltage feedforward signal using the frequency dynamic information obtained from the power control loop, quickly correcting the controller output response. This mechanism has high real-time performance, enabling intervention and regulation in the early stages of system instability, effectively mitigating the angular frequency offset problem caused by power imbalance. Figure 11 As shown in part (c), the system can still maintain dynamic consistency of frequency and phase after the disturbance occurs, achieving a significant enhancement in fault ride-through capability, maintaining stable operation of the system, and rapidly converging voltage and frequency fluctuations.

[0139] Therefore, the transient synchronization stabilization method for grid-connected hybrid systems proposed in this application reveals the adverse effects of grid-connected inverter voltage dynamics on the transient synchronization stability of grid-connected hybrid systems. The main advantage lies in utilizing the frequency deviation in the active power control loop as the voltage feedforward in the reactive power control loop. This method has the following advantages:

[0140] 1. The implementation and structure are very simple, involving only one state variable and no multiple feedback loops. It completely avoids the dependence of traditional stabilization strategies on communication links and there is no delay.

[0141] 2. Since the large frequency deviation only occurs during the transient period, the network hybrid system will not produce adverse effects during steady-state operation, and thus will not change the steady-state state of the system. Therefore, it is more in line with the IEEE 1547-2018 standard.

[0142] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0143] Based on the same inventive concept, this application also provides a transient synchronization stabilization device for a network-based hybrid system, used to implement the transient synchronization stabilization method for the network-based hybrid system described above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the transient synchronization stabilization device for a network-based hybrid system provided below can be found in the limitations of the transient synchronization stabilization method for the network-based hybrid system described above, and will not be repeated here.

[0144] In one embodiment, such as Figure 12 As shown, a transient synchronization stabilization device for a hybrid network system is provided, comprising:

[0145] The deviation acquisition module is used to acquire the frequency deviation in the active power control loop of the grid inverter when the grid inverter and / or the grid inverter in the grid-connected hybrid system are not in steady-state operation.

[0146] The reference voltage calculation module is used to introduce the frequency deviation into the reactive power control loop of the grid inverter and determine the reference voltage of the grid inverter based on the frequency deviation.

[0147] The voltage regulation module is used to adjust the output voltage of the grid inverter to match the reference voltage; the formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref - Q)+K(ω1-ω g ); where V 1ref V0 is the reference voltage of the grid-connected inverter, and K0 is the transient voltage of the grid-connected inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. ref Here, Q is the reactive power reference of the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power of the grid-connected inverter. g Let ω1-ω be the angular frequency of the power grid.g This represents the frequency deviation.

[0148] Each module in the transient synchronization stabilization device of the aforementioned hybrid network system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0149] In one embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0150] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

[0151] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0152] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0153] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0154] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A transient synchronization stabilization method for a hybrid network system, characterized in that, The method includes: Based on the current value of the grid voltage, detect whether there is a synchronization risk in the grid-connected hybrid system; wherein, if the current value of the grid voltage is detected to drop to zero and the grid-connected inverter and the grid-connected inverter themselves cannot complete fault ride-through, it is determined that there is a synchronization risk in the grid-connected hybrid system. If there is no synchronization risk in the grid-connected hybrid system, switch the control mode of the grid-connected hybrid system to parallel mode, and determine whether the grid-connected inverter and the grid-connected inverter are in steady-state operation. When the grid-connected inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in steady-state operation, the frequency deviation in the active power control loop of the grid-connected inverter is obtained. The frequency deviation is introduced into the reactive power control loop of the grid inverter, and the reference voltage of the grid inverter is determined based on the frequency deviation. Adjust the output voltage of the grid inverter to match the reference voltage; The formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref - Q)+K(ω1-ω g The control law formula for a grid-connected inverter is: ; Among them, V 1ref V0 is the reference voltage of the grid inverter, and K is the transient voltage of the grid inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. ref Here, Q is the reactive power reference of the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power of the grid-connected inverter. g Let ω1-ω be the angular frequency of the power grid. g For frequency deviation, J1 is the inertia of the grid inverter, and D is the frequency deviation. p1 It is the damping coefficient of the grid inverter, P ref It is the active power reference of the grid inverter, P is the output active power of the grid inverter, and t is time.

2. The method according to claim 1, characterized in that, The process of determining whether the grid-connected inverter in the grid-connected hybrid system is in a steady-state operating state includes: Determine the virtual potential reference and virtual potential of the grid-connected inverter; When the virtual potential reference and the virtual potential are matched, it is determined that the grid-connected inverter is in a steady-state operation state; When the virtual potential reference and the virtual potential do not match, it is determined that the grid-connected inverter is not in a steady-state operating state.

3. The method according to claim 2, characterized in that, The formula for calculating the virtual potential reference is: ; The formula for calculating the virtual potential is: ; Among them, V vref As a virtual potential reference, , , X g1 X is the transmission line impedance of the circuit where the grid inverter is located. g2 To determine the transmission line impedance of the circuit where the grid inverter is located, X g3 I2 is the transmission line impedance between the grid-connected hybrid system and the grid, I2 is the output current of the grid-connected inverter, and θ is the voltage across the grid. I It is the current injection angle of the grid inverter, V v This is a virtual electromotive force, where V1 is the output voltage of the grid-connected inverter, δ2 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E, and δ1 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E. 21 =δ2-δ1.

4. The method according to claim 3, characterized in that, The formula for calculating the power angle δ2 between the grid connection point voltage of the grid-connected inverter and the grid voltage E is: ； V2 is the grid connection point voltage of the grid-connected inverter.

5. The method according to claim 1, characterized in that, The process of determining whether the grid inverter in the grid-connected hybrid system is in a steady-state operating state includes: Determine the active power reference and output active power of the grid-connected inverter; When the active power reference and the output active power are matched, it is determined that the grid inverter is in a steady-state operation state; When the active power reference and the output active power do not match, it is determined that the grid inverter is not in a steady-state operation. The formula for calculating the output active power is as follows: ； P represents the output active power, I1 represents the output current of the grid inverter, and E represents the grid voltage.

6. The method according to claim 5, characterized in that, The formula for calculating the output current I1 of the grid inverter is as follows: ； V1 is the output voltage of the grid-connected inverter, and I2 is the output current of the grid-connected inverter. , X g1 X is the transmission line impedance of the circuit where the grid inverter is located. g3 To determine the transmission line impedance between the hybrid grid system and the power grid; δ2 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E, δ1 is the power angle between the grid connection point voltage of the grid-connected inverter and the grid voltage E, θ I It refers to the current injection angle of the grid inverter.

7. The method according to claim 1, characterized in that, The method further includes: In the event of a synchronization risk in the hybrid mesh system, the microcontroller in the hybrid mesh system is controlled to reduce the strength of the EPWM signal.

8. A transient synchronization stabilization device for a hybrid network system, characterized in that, The device includes: The deviation acquisition module is used to detect whether there is a synchronization risk in the grid-connected hybrid system based on the current value of the grid voltage. Specifically, if the current value of the grid voltage drops to zero and the grid-connected inverter and the grid-connected inverter cannot complete fault ride-through, it is determined that there is a synchronization risk in the grid-connected hybrid system. If there is no synchronization risk in the grid-connected hybrid system, the control mode of the grid-connected hybrid system is switched to parallel mode, and it is determined whether the grid-connected inverter and the grid-connected inverter are in a steady-state operating state. If the grid-connected inverter and / or the grid-connected inverter in the grid-connected hybrid system are not in a steady-state operating state, the frequency deviation in the active power control loop of the grid-connected inverter is acquired. A reference voltage calculation module is used to introduce the frequency deviation into the reactive power control loop of the grid inverter, and determine the reference voltage of the grid inverter based on the frequency deviation. A voltage regulation module is used to regulate the output voltage of the grid inverter to match the reference voltage; the formula for calculating the reference voltage is: V 1ref =V0+K q (Q ref - Q)+K(ω1-ω g The control law formula for a grid-connected inverter is: Among them, V 1ref V0 is the reference voltage of the grid inverter, and K is the transient voltage of the grid inverter. q Where Q is the reactive power gain, K is the proportional gain, and Q is the reactive power gain. ref Here, Q is the reactive power reference of the grid-connected inverter, ω1 is the angular frequency of the grid-connected inverter, and ω is the reactive power of the grid-connected inverter. g Let ω1-ω be the angular frequency of the power grid. g For frequency deviation, J1 is the inertia of the grid inverter, and D is the frequency deviation. p1 It is the damping coefficient of the grid inverter, P ref It is the active power reference of the grid inverter, P is the output active power of the grid inverter, and t is time.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the steps of the method according to any one of claims 1 to 7.

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