Phase jump fault ride-through method and device, storage medium and computer device

Abstract

This invention relates to the field of power electronic equipment control technology and discloses a method, apparatus, storage medium, and computer equipment for phase jump fault ride-through. The method includes calculating the power angle difference between the system power angle and the rated power angle of the target grid-type inverter and comparing it with a difference threshold; when a phase jump fault occurs, determining the corresponding power angle compensation value based on the rated power angle and the fault power angle under fault conditions; freezing the active power loop of the target grid-type inverter and applying the power angle compensation value to the output side of the active power loop; and when a current instantaneous value is detected to exceed a preset current threshold, limiting the reference current of the current inner loop of the target grid-type inverter. This method introduces power angle-based adaptive compensation and current limiting into the control loop, has a simple structure, requires no complex parameters, effectively addresses overcurrent and instability problems caused by phase jump faults, and improves system transient stability and fault ride-through capability.

Description

Technical Field

[0001] This invention relates to the field of power electronic equipment control technology, and in particular to a phase transition fault ride-through method, apparatus, storage medium, and computer equipment. Background Technology

[0002] With the continuous integration of large-scale new energy sources, such as wind power and photovoltaics, into the power grid, the power system is gradually evolving towards a dual-high form where high proportions of new energy power generation and high proportions of power electronic equipment coexist. Under this trend, the overall inertia and strength of the power system are significantly reduced, and various stability problems are becoming increasingly prominent. Traditional grid-connected inverters are difficult to maintain stable operation under weak grid conditions and lack active support capabilities. In contrast, grid-forming inverters controlled by virtual synchronous generators (VSG-GFMI) can provide necessary voltage and frequency support to the grid because they can simulate the characteristics of synchronous generators. This has become an important direction for current technology research and engineering applications.

[0003] However, in complex power grid environments, transient faults such as phase jumps may occur in the grid voltage. Under such faults, grid-connected inverters are prone to problems such as overcurrent, power oscillations, and even grid disconnection due to voltage source characteristics, which seriously affects the safe and stable operation of the system. Although there are some studies on fault ride-through for grid-connected inverters in the existing technology, there are still limitations. On the one hand, some methods rely on complex parameter identification and system modeling, which are not very adaptable and have a heavy computational burden. On the other hand, the existing strategies have limited effectiveness in suppressing overcurrent and power oscillations during faults, especially in terms of stable support and rapid recovery capabilities under severe operating conditions such as phase jumps. It is difficult to achieve effective transient ride-through control while taking into account simplicity and practicality.

[0004] Therefore, improving the dynamic stability, overcurrent suppression capability, and power support capability of grid-connected inverters under faults such as phase jumps remains a key technical problem that urgently needs to be solved. Summary of the Invention

[0005] In view of this, this application provides a phase transition fault ride-through method, apparatus, storage medium and computer equipment. The main purpose is to solve the technical problems of existing technologies in dealing with phase transition faults in grid-connected inverters, such as complex modeling, poor adaptability, and insufficient overcurrent and power oscillation suppression, making it difficult to balance practicality and effective ride-through.

[0006] According to a first aspect of the present invention, a phase-jump fault ride-through method is provided, applied to a grid-connected inverter based on virtual synchronous generator control, comprising: Calculate the power angle difference between the system power angle and the rated power angle of the target grid-type inverter, and compare the power angle difference with a preset difference threshold to determine whether the target grid-type inverter has experienced a phase jump fault; When the target grid-type inverter experiences a phase jump fault, the corresponding power angle compensation value is determined based on the rated power angle of the target grid-type inverter and the fault power angle of the target grid-type inverter under fault conditions. Freeze the active power loop of the target grid-type inverter and apply the power angle compensation value to the output side of the active power loop; When the instantaneous current value of the target grid-type inverter is detected to exceed the preset current threshold, the reference current of the inner current loop of the target grid-type inverter is limited.

[0007] Optionally, the rated power angle is calculated based on the rated values ​​of the internal potential, grid voltage, and total voltage of the line reactance and virtual reactance of the target grid-type inverter under rated operating conditions, and on the cosine theorem; the power angle difference is the absolute value of the difference between the system power angle and the rated power angle.

[0008] Optionally, the difference threshold is determined based on the inherent phase deviation limit and actual error tolerance of the target grid-type converter under standard load conditions.

[0009] Optionally, the fault power angle is calculated based on the internal potential of the target grid-type inverter under phase jump fault conditions, the grid voltage, and the total voltage value of line reactance and virtual reactance, and on the cosine theorem.

[0010] Optionally, when the internal potential phase of the target grid-type inverter leads the grid voltage, the power angle compensation value is the difference between the rated power angle and the fault power angle; when the internal potential phase of the target grid-type inverter lags behind the grid voltage, the power angle compensation value is the sum of the rated power angle and the fault power angle.

[0011] Optionally, the mathematical model of the active power loop of the target grid-type inverter is as follows:

[0012] In the formula, The phase angle of the internal potential of the target grid-type inverter; It is the moment of inertia; The actual active power value of the target grid-type inverter; The active power reference value for the target grid-type inverter; The active-frequency droop damping coefficient; This is the virtual speed rating; This is the actual value of the virtual rotational speed.

[0013] Optionally, the reference current of the current inner loop of the target grid-type inverter is subjected to amplitude limiting processing, including: normalizing the amplitude of the d-axis current reference value and q-axis current reference value of the voltage inner loop output of the target grid-type inverter based on the current threshold, to obtain the current inner loop input reference value after amplitude limiting.

[0014] According to a second aspect of the present invention, a phase transition fault ride-through device is provided, comprising: The fault diagnosis module is used to calculate the power angle difference between the system power angle and the rated power angle of the target grid-type inverter, and compare the power angle difference with a preset difference threshold to determine whether the target grid-type inverter has experienced a phase jump fault. The compensation value calculation module is used to determine the corresponding power angle compensation value based on the rated power angle of the target grid-type inverter and the fault power angle of the target grid-type inverter under the fault condition when a phase jump fault occurs in the target grid-type inverter. The compensation value application module is used to freeze the active power loop of the target grid-type inverter and apply the power angle compensation value to the output side of the active power loop; The current limiting module is used to limit the reference current of the inner current loop of the target grid-type inverter when the instantaneous current value of the target grid-type inverter is detected to exceed a preset current threshold.

[0015] According to a third aspect of the present invention, a storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the above-described phase transition fault traversal method.

[0016] According to a fourth aspect of the present invention, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described phase transition fault ride-through method.

[0017] This invention provides a phase-jump fault ride-through method, apparatus, storage medium, and computer equipment. It constructs a simple and adaptive fault detection and compensation method by calculating the power angle difference and comparing it with a preset threshold to determine the fault, and by determining the power angle compensation value based on the rated power angle and the fault power angle. This method does not rely on precise system models and complex online parameter identification; it makes decisions solely based on directly measurable or calculable power angle information, reducing dependence on system parameters and computational burden, thereby improving adaptability and practicality under different operating conditions. Furthermore, by freezing the active power loop and applying the power angle compensation value, and by limiting the reference current of the inner current loop, it directly intervenes in key variables during the fault transient process. Applying the power angle compensation value can quickly correct the internal potential phase, directly stabilizing the system power angle and supporting active power output, thus effectively suppressing power oscillations. The limiting of the current reference value constrains the current command at the source, directly suppressing instantaneous overcurrent. The synergistic effect of these two methods enables the system to simultaneously achieve effective active power support, timely overcurrent suppression, and rapid recovery after the fault during a phase-jump fault. The above method introduces adaptive compensation and current limiting based on power angle into the control loop. It has a simple structure and does not require complex parameters. It effectively addresses the overcurrent and instability problems caused by phase jump faults and improves the system's transient stability and fault ride-through capability.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 A schematic flowchart of a phase jump fault ride-through method provided by an embodiment of the present invention is shown; Figure 2 This invention provides a phase jump fault ride-through method, which illustrates the voltage and current phasor diagram of a target grid-type inverter under normal grid-connected conditions. Figure 3 This invention provides a phase jump fault ride-through method, which illustrates the voltage and current phasor diagram of a target grid-type inverter under phase jump fault conditions. Figure 3 (a) shows the voltage and current phasor diagram of the target grid-type inverter under the fault condition of phase lag jump in a phase jump fault ride-through method provided by an embodiment of the present invention; Figure 3 (b) shows the voltage and current phasor diagram of the target grid-type inverter under the fault condition of phase lead jump in a phase jump fault ride-through method provided by an embodiment of the present invention; Figure 4 This invention provides a phase jump fault ride-through method, which illustrates the voltage and current phasor diagrams of a target grid-type inverter under different phase jump angle conditions. Figure 4 (a) shows the voltage and current phasor diagram of the target grid-type inverter when the phase jump angle is less than 0 in a phase jump fault ride-through method provided by an embodiment of the present invention. Figure 4 (b) shows the voltage and current phasor diagram of the target grid-type inverter in a phase jump angle greater than 0 in a phase jump fault ride-through method provided by an embodiment of the present invention; Figure 4 (c) shows the voltage and current phasor diagram of the target grid-type inverter in case two when the phase jump angle is greater than 0 in a phase jump fault ride-through method provided by an embodiment of the present invention; Figure 4 (d) shows the voltage and current phasor diagram of the target grid-type inverter in case three when the phase jump angle is greater than 0 in a phase jump fault ride-through method provided by an embodiment of the present invention; Figure 5 This invention provides an embodiment of a phase jump fault ride-through method with an improved active power loop control for a target grid-type inverter. Figure 6 This invention provides a phase jump fault ride-through method, which includes a comparison of the power angle curves of the target grid-type inverter before and after power angle compensation is added to the active power loop. Figure 6 (a) shows a schematic diagram of the conventional power angle curve of the target grid-type inverter in a phase jump fault ride-through method provided by an embodiment of the present invention; Figure 6 (b) shows a schematic diagram of the improved power angle curve of the target grid-type inverter in a phase jump fault ride-through method provided in an embodiment of the present invention; Figure 7 This invention provides an improved current inner loop control block diagram for a target grid-type inverter in a phase jump fault ride-through method according to an embodiment of the present invention. Figure 8 This diagram shows an overall block diagram of a phase jump fault ride-through method provided by an embodiment of the present invention; Figure 9 This invention provides a block diagram of the target grid-type inverter main circuit topology and control structure in a phase jump fault ride-through method according to an embodiment of the present invention. Figure 10 The figure shows a comparison of simulation results between the phase jump fault ride-through method provided by an embodiment of the present invention and the traditional VSG method under the condition of grid voltage phase lag jump fault. Figure 10 (a) shows the simulation results of the active power at the PCC point of a phase jump fault ride-through method provided by an embodiment of the present invention at a phase jump of -30° compared with that of the traditional VSG method; Figure 10 (b) shows the simulation results of the reactive power at the PCC point of a phase jump fault ride-through method provided by an embodiment of the present invention at a phase jump of -30° compared with that of the traditional VSG method; Figure 10 (c) shows the simulation results of the effective value of the PCC point current of a phase jump fault ride-through method provided by an embodiment of the present invention at a phase jump of -30° and the traditional VSG method; Figure 10 (d) shows the simulation results of the system power angle values ​​of a phase jump fault ride-through method provided by an embodiment of the present invention at a phase jump of -30° and the traditional VSG method; Figure 10 (e) shows the simulation results of the system power angle value when the phase jump fault ride-through method provided by an embodiment of the present invention is -30° phase jump; Figure 10 (f) shows the simulation results of the power angle compensation value of a phase jump fault ride-through method provided in an embodiment of the present invention when the phase jump is -30°; Figure 11 The figure shows a comparison of simulation results between the phase jump fault ride-through method provided by an embodiment of the present invention and the traditional VSG method under the condition of grid voltage phase lead jump fault. Figure 11 (a) shows the simulation results of the active power at the PCC point of a phase jump fault ride-through method provided by an embodiment of the present invention when the phase jump is 30° compared with that of the traditional VSG method; Figure 11 (b) shows the simulation results of the reactive power at the PCC point of a phase jump fault ride-through method provided by an embodiment of the present invention when the phase jump is 30° compared with that of the traditional VSG method; Figure 11 (c) shows the simulation results of the effective value of the PCC point current of a phase jump fault ride-through method provided by an embodiment of the present invention when the phase jump is 30° compared with that of the traditional VSG method; Figure 11 (d) shows the simulation results of the system power angle values ​​of a phase jump fault ride-through method provided by an embodiment of the present invention with a phase jump of 30° and the traditional VSG method; Figure 11 (e) shows the simulation results of the system power angle value when the phase jump is 30°, according to an embodiment of the present invention, a phase jump fault ride-through method provided by the present invention. Figure 11 (f) shows the simulation results of the power angle compensation value of a phase jump fault ride-through method provided in an embodiment of the present invention when the phase jump is 30°; Figure 12 This diagram illustrates the structure of a phase jump fault ride-through device according to an embodiment of the present invention. Figure 13 A schematic diagram of the device structure of a computer device provided in an embodiment of the present invention is shown. Detailed Implementation

[0020] Exemplary embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0021] This application provides a phase-jump fault ride-through method, applied to a grid-connected inverter based on virtual synchronous generator control, such as... Figure 1 As shown, the method includes the following steps: 101. Calculate the power angle difference between the system power angle and the rated power angle of the target grid-type inverter, and compare the power angle difference with the preset difference threshold to determine whether the target grid-type inverter has experienced a phase jump fault.

[0022] The rated power angle is calculated based on the rated values ​​of the internal potential, grid voltage, and total voltage of the line reactance and virtual reactance of the target grid-type inverter under rated operating conditions, and is obtained based on the cosine theorem. The power angle difference is the absolute value of the difference between the system power angle and the rated power angle. The difference threshold is determined based on the inherent phase deviation limit and actual error tolerance of the target grid-type converter under standard load conditions.

[0023] Specifically, this step introduces a phase jump fault detection module. Under normal operating conditions, such as... Figure 2 As shown, the internal potential, grid voltage, and rated values ​​of the line reactance and the total voltage of the virtual reactance of the grid-connected inverter (VSG-GFMI) based on virtual synchronous generator control satisfy a vector triangle relationship. Therefore, the relationship can be obtained as follows:

[0024] In the formula, E is the internal electromotive force of the target grid-type inverter under normal operating conditions; V gV represents the mains voltage under normal operating conditions. X This is the rated value of the total voltage of the line reactance and virtual reactance under normal operating conditions; The rated power angle of the target grid-type inverter.

[0025] Based on this, the expression for the rated power angle of the target grid-type inverter is obtained as follows:

[0026] The expression for the difference in work angle is:

[0027] In the formula, The difference in work angle, The system power angle of the target grid-type inverter.

[0028] Meanwhile, considering that the existing technical specifications for grid-type energy storage converters stipulate that the phase deviation of the AC output voltage of the grid-type converter should be less than 3° under no-load and rated resistive load conditions, and that there are also errors in actual testing and calculation, the threshold is set to 5° after leaving a margin.

[0029] 102. When a phase jump fault occurs in the target grid-type inverter, the corresponding power angle compensation value shall be determined based on the rated power angle of the target grid-type inverter and the fault power angle of the target grid-type inverter under fault conditions.

[0030] This step introduces an adaptive power angle compensation value calculation module. The fault power angle is calculated based on the internal potential of the target grid-type inverter under phase jump fault conditions, the grid voltage, and the total voltage value of line reactance and virtual reactance, and is based on the cosine theorem. When the phase of the internal potential of the target grid-type inverter leads the grid voltage, the power angle compensation value is the difference between the rated power angle and the fault power angle. When the phase of the internal potential of the target grid-type inverter lags the grid voltage, the power angle compensation value is the sum of the rated power angle and the fault power angle.

[0031] like Figure 3 (a) and Figure 3 As shown in (b), under the phase jump fault condition, the internal potential, grid voltage, line reactance, and total voltage value of the virtual reactance of the target grid-type inverter satisfy a vector triangle relationship. Therefore, the following relationship can be obtained:

[0032] In the formula, Internal potential of a grid-type inverter under phase jump fault conditions; This refers to the grid voltage under phase transition fault conditions. This is the rated value of the total voltage of the line reactance and virtual reactance under phase-jump fault conditions; The fault angle of the target grid-type inverter.

[0033] When a phase jump fault occurs in the grid voltage, the grid voltage amplitude remains unchanged, and the internal potential of the target grid-type inverter remains unchanged for a short period of time. Therefore, E=E F V g =V gF .

[0034] Further solving yields the expression for the fixed power angle of the target grid-type inverter:

[0035] Next, the power angle compensation value under the phase jump fault condition is calculated based on the rated power angle and fault power angle of the target grid-type inverter. Furthermore, it is necessary to analyze different phase jump fault conditions to obtain the power angle compensation value under different fault conditions. Specifically, if counterclockwise is considered positive and clockwise is considered negative, the grid voltage phase jump can be divided into the following four cases: The first type is the grid voltage phase jump angle. When g < 0, such as Figure 4 As shown in (a), under this operating condition, the phase difference between the internal potential of the target grid-type inverter and the grid voltage is positive, and the power angle compensation value is... = g= - .

[0036] The second type is the grid voltage phase jump angle. When g > 0, there are three specific cases: Scenario 1, such as Figure 4 As shown in (b), under this operating condition, the phase difference between the internal potential of the target grid-type inverter and the grid voltage is positive, and the power angle compensation value is... = g= - .

[0037] Scenario two is, such as Figure 4 As shown in (c), under this operating condition, the phase difference between the internal potential of the target grid-type inverter and the grid voltage is negative, and the power angle compensation value is... = g= + .

[0038] Scenario three is, such as Figure 4 As shown in (d), under this operating condition, the phase difference between the internal potential of the target grid-type inverter and the grid voltage is negative, and the power angle compensation value is... = g= + .

[0039] Based on the above four scenarios, it can be concluded that when the internal potential phase of the target grid-type inverter leads the grid voltage, i.e., the phase difference between the internal potential and the grid voltage is positive, the power angle compensation value is the difference between the rated power angle and the fault power angle. = g= - When the internal potential phase of the target grid-connected inverter lags behind the grid voltage, i.e., the phase difference between the internal potential and the grid voltage is negative, the power angle compensation value is the sum of the rated power angle and the fault power angle. = g= + .

[0040] 103. Freeze the active power loop of the target grid-type inverter and apply the power angle compensation value to the output side of the active power loop.

[0041] The mathematical model for the active power loop of the target grid-type inverter is as follows:

[0042] In the formula, The phase angle of the internal potential of the target grid-type inverter; It is the moment of inertia; The actual active power value of the target grid-type inverter; The active power reference value for the target grid-type inverter; The active-frequency droop damping coefficient; This is the virtual speed rating; This is the actual value of the virtual rotational speed.

[0043] Specifically, this step introduces an active power loop freeze judgment module. The control block diagram of the active power loop of the target grid-type inverter after adding the improved scheme is shown below. Figure 5 As shown, the specific improvement method is as follows: when a grid voltage phase jump fault is detected, the angle of the active power loop output of the target grid-type inverter before the fault is frozen. Then, an adaptive power angle compensation value calculation module is added to the output of the active power loop. After the fault is detected and cleared, the control function of the active power loop is restored, and the power angle compensation is stopped. The control state switching of the above two improvement links is realized by switches S1 and S2.

[0044] Furthermore, the power angle stability of the active power loop of the target grid-type inverter before and after the addition of the improved scheme can be analyzed using the power angle curve. Figure 6(a) It can be seen that before the improvement scheme was added, when the grid voltage experienced phase jump fault I (small phase jump angle and Δθg>0) and phase jump fault II (small phase jump angle and Δθg<0), the target grid-type inverter stabilized at point A after a period of reciprocating transient process; when the grid voltage experienced phase jump fault III (large phase jump angle and Δθg<0), the target grid-type inverter exhibited transient instability; and according to Figure 6 (b) It can be seen that after adding the improvement scheme, when the grid voltage experiences phase jump fault I and phase jump fault II, the operating point of the target grid-type inverter instantly jumps back to near point A from point B and point C respectively, and can therefore remain stable at point A. Further comparing the results before adding the improvement scheme, when the fault occurs, the difference between the power angle of the target grid-type inverter system and the rated power angle is almost 0, the transient process is extremely short and almost non-existent, and the active power fluctuation is relatively small, so it can provide power angle compensation and active power support. When the grid voltage experiences phase jump fault III, the operating point of the target grid-type inverter instantly changes from point D to near point A, and can therefore remain stable at point A. Through comparison, it can be seen that the improvement scheme can not only improve the power angle stability of the target grid-type inverter, but also provide power angle compensation and active power support.

[0045] 104. When the instantaneous current value of the target grid-type inverter is detected to exceed the preset current threshold, the reference current of the inner current loop of the target grid-type inverter is limited.

[0046] Specifically, the d-axis current reference value and q-axis current reference value of the voltage inner loop output of the target grid-type inverter are normalized based on the current threshold to obtain the current inner loop input reference value after limiting.

[0047] Specifically, since the short-circuit current level that power electronics can withstand is only 1.2-1.5 pu, this application preferably uses 1.2 pu.

[0048] Furthermore, this step introduces a limiting module, which is used for the inner current loop of the target grid-type inverter, including d-axis current limiting and q-axis current limiting, and its expression is:

[0049] In the formula, I th It is the current threshold; I dref It is the d-axis current reference value output by the inner voltage loop; I qref It is the q-axis current reference value output by the inner voltage loop; I dref1 It is the input reference value for the d-axis current of the inner current loop; I qref1 It is the input reference value for the q-axis current of the inner current loop.

[0050] The control block diagram of the target grid-type inverter after incorporating the improved scheme into the current inner loop is as follows: Figure 7 As shown, the specific improvement method is as follows: when the output current of the target grid-type inverter does not exceed the current threshold, the output of the voltage inner loop is maintained as the input of the current inner loop, that is, the current reference value is I. dref and I qref When the current exceeds the current threshold, the output of the voltage inner loop is proportionally reduced and then input to the current inner loop; that is, the current reference value is I. dref1 and I qref1 The control state switching of the limiting module is achieved by switches S3 and S4.

[0051] In summary, the overall block diagram of the phase transition fault ride-through method for grid-type inverters based on adaptive power angle compensation proposed in this invention is as follows: Figure 8 As shown, to verify the effectiveness and superiority of the method proposed in this application, a system was built in the MATLAB / Simulink platform as follows: Figure 9 The grid-type inverter system model is shown below, and the proposed method is compared with the traditional VSG method in the simulation. The key parameters used in the simulation are shown in the table below.

[0052]

[0053] According to the technical specifications for grid-type energy storage converters, the converter should be able to operate stably under the condition that the phase angle change of the grid voltage is no more than 30°. Therefore, the verification example will be carried out under the most severe operating condition with a phase jump of ±30°.

[0054] In an embodiment of the phase jump fault ride-through method provided in this application, specifically for a grid voltage phase lag jump fault: using the grid voltage phasor under normal operating conditions as the reference phasor and taking counterclockwise as positive, under a grid voltage phase lag jump fault, the phase jump angle is less than zero. In this example, the grid voltage phase jump angle Δθg = Taking a 30° scenario as an example, during the normal grid connection process of a grid-connected inverter, if a phase jump fault occurs in the grid voltage at t=3 s and the jump angle Δθg= After a 30° angle and t = 3.5 s interval, the fault is cleared and the system returns to normal operating conditions. The simulation results of the method disclosed in this application and the traditional VSG method under this fault condition are shown in the figure below. Figure 10 As shown.

[0055] like Figure 10As shown in (a) and (b), when using traditional control methods, grid-connected inverters exhibit significant fluctuations and large transient impacts in both active and reactive power at the PCC point during the fault occurrence and recovery phases. In contrast, the method disclosed in this application enables the system to quickly recover to a steady state within 120 ms and significantly reduces power impacts. Specifically, the maximum transient impacts of active and reactive power are reduced from 1.68 pu and 0.34 pu to 1.07 pu (a reduction of 36.3%) and 0.18 pu (a reduction of 47.1%), respectively. During the fault, the fluctuations in active and reactive power are reduced from 1.28 pu and 0.41 pu to 0.35 pu (a reduction of 72.7%) and 0.28 pu (a reduction of 31.7%). Therefore, the method disclosed in this application enables grid-connected inverters to quickly establish active power support during phase transition faults and effectively suppress power impacts and fluctuations.

[0056] like Figure 10 As shown in (c), when the grid-type inverter adopts the traditional control method, the current at the PCC point cannot be stably output during the entire fault and recovery period. The maximum and minimum effective values ​​of the current reach 1.86 pu and 0.28 pu, respectively. By using the method disclosed in this application, the maximum and minimum effective values ​​of the current can be improved to 1.12 pu and 0.66 pu, respectively. As a result, the current at the PCC point can quickly enter a steady state, where the steady-state current component can be maintained near the rated current. The inrush current at the moment of fault occurrence and clearing can be effectively suppressed to within 1.2 pu. The simulation results verify the advantages of the method proposed in this invention in response speed and overcurrent suppression.

[0057] Figure 10 (d) shows the system power angle of the grid-connected inverter using two methods. When the traditional control method is used, the system power angle fluctuates continuously. The maximum upward impact during a fault reaches 75.94°, and the minimum downward impact during fault clearing reaches 15.04°. When the method disclosed in this application is used, the system power angle fluctuation is smaller, and the grid-connected inverter can operate near the rated power angle. In addition, due to the input of the adaptive power angle compensation value calculation module, although there are impacts during fault occurrence and clearing, the time is extremely short and can be ignored. Therefore, the method disclosed in this application is superior in suppressing power angle fluctuations.

[0058] Figure 10 (e) and (f) illustrate the power angle compensation process of the method disclosed in this application, where the rated power angle and the fault power angle obtained by the adaptive power angle compensation value calculation module during the fault are δ N =42.66°、δ F =72.69°, the power angle compensation value is Δδ= 30.06°, and according to theoretical analysis of this operating condition, the system power angle compensation value should be Δθg = 30°≈Δδ demonstrates the correctness and effectiveness of the adaptive power angle compensation value calculation module.

[0059] Therefore, under grid voltage phase lag switching faults, compared with traditional control methods, the method disclosed in this application can enable grid-type inverters to achieve the goals of active power support and fault overcurrent suppression during fault and recovery periods, while effectively suppressing power surges and fluctuations.

[0060] In another embodiment of the phase jump fault ride-through method provided in this application, namely, a grid voltage phase lead jump fault: under a grid voltage phase lead jump fault, the phase jump angle is greater than zero. This example takes a scenario where the grid voltage phase jump angle Δθg = 30° as an example. During the normal grid connection process of a grid-connected inverter, a grid voltage phase jump fault occurs at t = 3s with a jump angle Δθg = 30°. After t = 3.5s, the fault is cleared, and the system returns to normal operating conditions. The simulation results of the method disclosed in this application and the traditional VSG method under this fault condition are shown in the figure below. Figure 11 As shown.

[0061] Therefore, when using traditional control methods, grid-connected inverters exhibit significant fluctuations and transient impacts in active and reactive power at the PCC point during phase transition faults and recovery periods, such as... Figure 11 As shown in (a) and (b), in contrast, the method disclosed in this application not only enables the grid-type inverter to quickly reach a power steady state within 100ms, but also effectively suppresses power surges and fluctuations at the PCC point. Specifically, the maximum surges in active and reactive power are reduced from 1.60 pu and 0.27 pu to 1.04 pu (a decrease of 35.0%) and 0.11 pu (a decrease of 59.3%), respectively; the maximum fluctuations in active and reactive power are reduced from 1.29 pu and 0.38 pu to 0.38 pu (a decrease of 70.5%) and 0.19 pu (a decrease of 50.0%). Therefore, the grid-type inverter using the method disclosed in this application can quickly provide active power support during phase transition faults and has good suppression capabilities for power surges and fluctuations.

[0062] like Figure 11As shown in (c), during the entire phase transition fault process, the current at the PCC point of the grid-connected inverter using the traditional control method exhibits significant fluctuations and surges, with the highest and lowest effective values ​​reaching 1.79 pu and 0.21 pu, respectively. The method disclosed in this application can improve the maximum and minimum effective values ​​of the current to 1.07 pu and 0.53 pu, respectively, thereby allowing the current at the PCC point to quickly enter a steady state. The steady-state component can be maintained near the rated current value, and the transient surge current can be effectively suppressed to within 1.2 pu. Therefore, the method disclosed in this application can effectively solve the problem of current surges and fluctuations during faults.

[0063] from Figure 11 (d) It can be observed that the power angle of the grid-type inverter is under two methods when a phase jump fault is used. The traditional control method cannot stabilize the power angle. When the fault occurs, the lowest downward impact of the power angle reaches 9.72°, and when the fault is cleared, the highest upward impact of the power angle reaches 71.14°. When the method disclosed in this application is used, the power angle fluctuation of the system is effectively suppressed, and the grid-type inverter can operate at the rated power angle. In addition, due to the input of the adaptive power angle compensation value calculation module, there are transient impacts when the fault occurs and is cleared, but the time is extremely short and can be ignored. Therefore, the method disclosed in this invention has good performance in suppressing power angle impacts and fluctuations.

[0064] Specifically, it can be seen from Figure 11 (e) and (f) provide a detailed observation of the power angle compensation process of the method disclosed in this application. During a phase-jump fault, the adaptive power angle compensation value calculation module obtains the rated power angle, fault power angle, and power angle compensation value of the grid-type inverter as δ. N =42.66°、δ F =13.05°, Δδ= 29.61°. According to the theoretical analysis of this working condition, the system power angle compensation value should be Δθg=30°≈Δδ, which also reflects the correctness and effectiveness of the adaptive power angle compensation value calculation module.

[0065] Therefore, under the fault of voltage phase leading jump in the power grid, the method disclosed in this application can achieve the goals of active power support, power surge suppression and overcurrent suppression during the fault and recovery period, which is superior to traditional control methods.

[0066] In summary, the method disclosed in this application only involves local improvements to the active power loop and the inner current loop, without complex parameter design, thus reducing implementation complexity and improving engineering practicality. Specifically, under grid voltage phase jump faults, the method disclosed in this application can compensate the internal potential phase angle of the grid-connected inverter in real time, improving the power angle stability of the system. Compared with the traditional VSG control method, it enables the grid-connected inverter to provide active power support during faults and has good overcurrent suppression, power fluctuation suppression, and fault recovery capabilities. In the most severe operating condition, i.e., grid voltage phase jump... At 30°, the method disclosed in this application reduces the maximum fluctuation values ​​of active and reactive power by 72.7% and 31.7%, respectively.

[0067] Furthermore, as Figure 1 In terms of specific implementation of the method, this application provides a phase transition fault ride-through device, such as... Figure 12 As shown, the device includes: a fault judgment module 301, a compensation value calculation module 302, a compensation value application module 303, and a current limiting module 304.

[0068] The fault judgment module 301 is used to calculate the power angle difference between the system power angle and the rated power angle of the target grid-type inverter, and compare the power angle difference with a preset difference threshold to determine whether the target grid-type inverter has experienced a phase jump fault. The compensation value calculation module 302 is used to determine the corresponding power angle compensation value based on the rated power angle of the target grid-type inverter and the fault power angle of the target grid-type inverter under the fault condition when a phase jump fault occurs in the target grid-type inverter. The compensation value application module 303 is used to freeze the active power loop of the target grid-type inverter and apply the power angle compensation value to the output side of the active power loop. The current limiting module 304 is used to limit the reference current of the inner current loop of the target grid-type inverter when the instantaneous current value of the target grid-type inverter is detected to exceed the preset current threshold.

[0069] In specific application scenarios, the rated power angle in the fault judgment module 301 is calculated based on the rated values ​​of the internal potential, grid voltage, and total voltage of the line reactance and virtual reactance of the target grid-type inverter under rated operating conditions, and is based on the cosine theorem; the power angle difference is the absolute value of the difference between the system power angle and the rated power angle.

[0070] In specific application scenarios, the difference threshold in the fault judgment module 301 is determined based on the inherent phase deviation limit and actual error tolerance of the target grid-type converter under standard load conditions.

[0071] In specific application scenarios, the fault power angle in the compensation value calculation module 302 is calculated based on the internal potential of the target grid-type inverter under the phase jump fault condition, the grid voltage, and the total voltage value of the line reactance and virtual reactance, and is based on the cosine theorem.

[0072] In specific application scenarios, in the compensation value calculation module 302, when the phase of the internal potential of the target grid-type inverter leads the grid voltage, the power angle compensation value is the difference between the rated power angle and the fault power angle; when the phase of the internal potential of the target grid-type inverter lags behind the grid voltage, the power angle compensation value is the sum of the rated power angle and the fault power angle.

[0073] In specific application scenarios, the mathematical model of the active power loop of the target grid-type inverter in the compensation value application module 303 is as follows:

[0074] In the formula, The phase angle of the internal potential of the target grid-type inverter; It is the moment of inertia; The actual active power value of the target grid-type inverter; The active power reference value for the target grid-type inverter; The active-frequency droop damping coefficient; This is the virtual speed rating; This is the actual value of the virtual rotational speed.

[0075] In specific application scenarios, the current limiting module 304 is used to perform amplitude normalization processing on the d-axis current reference value and q-axis current reference value of the voltage inner loop output of the target grid-type inverter based on the current threshold, so as to obtain the current inner loop input reference value after limiting.

[0076] It should be noted that other corresponding descriptions of the functional units involved in the phase jump fault ride-through device provided in this embodiment can be found in [reference needed]. Figure 1 The corresponding description in [the document] will not be repeated here.

[0077] Based on the above, Figure 1 Accordingly, this embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the aforementioned phase transition fault ride-through method.

[0078] Based on this understanding, the technical solution of this application can be embodied in the form of a software product. The software product to be identified can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, or portable hard drive), including several instructions to enable a computer device (such as a personal computer, server, or network device) to execute the phase transition fault traversal method of various implementation scenarios of this application.

[0079] Based on the above, Figure 1 The method shown, and Figure 12 The illustrated embodiment of the phase-jump fault ride-through device is designed to achieve the above objectives, such as... Figure 13 As shown, this embodiment also provides a physical device for phase transition fault ride-through. This device includes a communication bus, a processor, a memory, and a communication interface. It may also include input / output interfaces and a display device. The various functional units can communicate with each other via the bus. The memory stores a computer program, and the processor executes the program stored in the memory to perform the phase transition fault ride-through method described in the above embodiment.

[0080] Optionally, the physical device may also include a user interface, a network interface, a camera, radio frequency (RF) circuitry, sensors, audio circuitry, a Wi-Fi module, etc. The user interface may include a display screen, input units such as a keyboard, etc., and optional user interfaces may also include USB interfaces, card reader interfaces, etc. The network interface may optionally include standard wired interfaces, wireless interfaces (such as Wi-Fi interfaces), etc.

[0081] Those skilled in the art will understand that the phase transition fault crossing physical device structure provided in this embodiment does not constitute a limitation on the physical device, and may include more or fewer components, or combine certain components, or have different component arrangements.

[0082] The storage medium may also include an operating system and a network communication module. The operating system is a program that manages the hardware and software resources of the aforementioned physical device, supporting the operation of information processing programs and other software and / or programs to be identified. The network communication module is used to enable communication between the various components within the storage medium, as well as communication with other hardware and software in the information processing physical device.

[0083] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platform, or it can be implemented by hardware. By applying the technical solution of this application, a simple and adaptive fault detection and compensation method is constructed by calculating the power angle difference and comparing it with a preset threshold to determine the fault, and by determining the power angle compensation value based on the rated power angle and the fault power angle. This method does not rely on a precise system model and complex online parameter identification, but only on the power angle information that can be directly measured or calculated, reducing the dependence on system parameters and the computational burden, thereby improving the adaptability and practicality under different operating conditions. Furthermore, by freezing the active power loop and applying the power angle compensation value, and by limiting the reference current of the current inner loop, the key variables in the fault transient process are directly intervened. Applying the power angle compensation value can quickly correct the internal potential phase, directly stabilize the system power angle and support the active power output, thereby effectively suppressing power oscillation. The limiting of the current reference value constrains the current command from the source and directly suppresses instantaneous overcurrent. The synergistic effect of the two enables the system to simultaneously achieve effective support of active power, timely suppression of overcurrent and rapid recovery after the fault during phase jump faults. The above method introduces adaptive compensation and current limiting based on power angle into the control loop. It has a simple structure and does not require complex parameters. It effectively addresses the overcurrent and instability problems caused by phase jump faults and improves the system's transient stability and fault ride-through capability.

[0084] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing this application. Those skilled in the art will understand that the modules in the apparatus of the embodiment can be distributed within the apparatus of the embodiment as described, or can be modified to be located in one or more apparatuses different from this embodiment. The modules of the above-described embodiment can be combined into one module, or further divided into multiple sub-modules.

[0085] The serial numbers in this application are for descriptive purposes only and do not represent the superiority or inferiority of any particular implementation scenario. The above disclosures are merely a few specific implementation scenarios of this application; however, this application is not limited thereto, and any variations conceived by those skilled in the art should fall within the protection scope of this application.

Claims

1. A phase-jump fault ride-through method, applied to a grid-type inverter based on virtual synchronous generator control, characterized in that, include: Calculate the power angle difference between the system power angle and the rated power angle of the target grid-type inverter, and compare the power angle difference with a preset difference threshold to determine whether the target grid-type inverter has experienced a phase jump fault; When the target grid-type inverter experiences a phase jump fault, the corresponding power angle compensation value is determined based on the rated power angle of the target grid-type inverter and the fault power angle of the target grid-type inverter under fault conditions. Freeze the active power loop of the target grid-type inverter and apply the power angle compensation value to the output side of the active power loop; When the instantaneous current value of the target grid-type inverter is detected to exceed the preset current threshold, the reference current of the inner current loop of the target grid-type inverter is limited.

2. The method according to claim 1, characterized in that, The rated power angle is calculated based on the rated values ​​of the internal potential, grid voltage, and total voltage of the line reactance and virtual reactance of the target grid-type inverter under rated operating conditions, and is obtained based on the cosine theorem. The power angle difference is the absolute value of the difference between the system's power angle and the rated power angle.

3. The method according to claim 1, characterized in that, The difference threshold is determined based on the inherent phase deviation limit and actual error tolerance of the target grid converter under standard load conditions.

4. The method according to claim 1, characterized in that, The fault angle is calculated based on the internal potential of the target grid-type inverter under phase jump fault conditions, the grid voltage, and the total voltage value of line reactance and virtual reactance, and is based on the cosine theorem.

5. The method according to claim 1, characterized in that, When the internal potential phase of the target grid-type inverter leads the grid voltage, the power angle compensation value is the difference between the rated power angle and the fault power angle; When the internal potential phase of the target grid-type inverter lags behind the grid voltage, the power angle compensation value is the sum of the rated power angle and the fault power angle.

6. The method according to claim 1, characterized in that, The mathematical model of the active power loop of the target grid-type inverter is as follows: In the formula, The phase angle of the internal potential of the target grid-type inverter; It is the moment of inertia; The actual active power value of the target grid-type inverter; The active power reference value for the target grid-type inverter; The active-frequency droop damping coefficient; This is the virtual speed rating; This is the actual value of the virtual rotational speed.

7. The method according to claim 1, characterized in that, Limiting the reference current of the inner current loop of the target grid-type inverter includes: Based on the current threshold, the d-axis current reference value and q-axis current reference value of the voltage inner loop output of the target grid-type inverter are normalized to obtain the current inner loop input reference value after limiting.

8. A phase-jump fault ride-through device, characterized in that, include: The fault diagnosis module is used to calculate the power angle difference between the system power angle and the rated power angle of the target grid-type inverter, and compare the power angle difference with a preset difference threshold to determine whether the target grid-type inverter has experienced a phase jump fault. The compensation value calculation module is used to determine the corresponding power angle compensation value based on the rated power angle of the target grid-type inverter and the fault power angle of the target grid-type inverter under the fault condition when a phase jump fault occurs in the target grid-type inverter. The compensation value application module is used to freeze the active power loop of the target grid-type inverter and apply the power angle compensation value to the output side of the active power loop; The current limiting module is used to limit the reference current of the inner current loop of the target grid-type inverter when the instantaneous current value of the target grid-type inverter is detected to exceed a preset current threshold.

9. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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