Transient stability enhancement control method and device for network-forming converter, terminal and medium

Abstract

The invention discloses a transient stability enhancement control method and device for a network-forming converter, a terminal and a medium. According to the scheme, on the basis of matching control logic, a virtual power angle difference value is introduced to serve as an additional control variable, so that the converter can respond to direct-current voltage fluctuation and power angle deviation at the same time; therefore, when the phase jump or power fluctuation of the power grid occurs, the output angular frequency of the grid-forming converter can quickly respond to the phase jump by dynamically adjusting the virtual power angle reference value, so that the stability of the direct-current bus voltage is enhanced, and the phenomena of power angle oscillation and voltage instability in the transient process are inhibited.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of converter stability control, in particular to a network-forming converter transient stability enhancement control method and device, a terminal and a medium. BACKGROUND

[0002] With the rapid growth of renewable energy, the traditional power grid relying on synchronous generators gradually changes into a distributed converter-dominated grid. To solve the problems of power system frequency instability, lack of inertia, damping and other problems caused by the continuous increase of new energy generation penetration and the continuous decrease of synchronous generator proportion in the power system, researchers have proposed a network-forming converter control strategy by simulating the external characteristics of synchronous generators. Network-forming converters can provide virtual inertia and damping to effectively support the grid voltage and frequency, so they can rely on themselves to establish an output voltage that can achieve extremely weak grid operation and island operation. Therefore, network-forming converters play an important role in new power systems characterized by "high proportion of renewable energy and high proportion of power electronic equipment".

[0003] As a kind of network-forming control strategy, the matching control strategy can realize synchronization with the grid by controlling the DC bus voltage of the converter to adjust the output angular frequency. However, in actual application, the network-forming converter with traditional matching control is prone to transient instability and DC voltage instability when facing grid phase jump disturbance, and has the technical problem of poor stability. SUMMARY

[0004] The present application provides a network-forming converter transient stability enhancement control method, device, terminal and medium, which is used to solve the technical problem of poor stability of the existing matching control network-forming converter when facing grid phase jump disturbance.

[0005] To solve the above technical problems, the first aspect of the present application provides a network-forming converter transient stability enhancement control method, comprising:

[0006] Obtaining the public connection point voltage phase and the converter output voltage phase of the network-forming converter;

[0007] Calculating the phase difference between the converter output voltage phase and the public connection point voltage phase, and determining the virtual power angle according to the phase difference;

[0008] According to the difference between the virtual power angle and the virtual power angle reference value, and combining a preset improved matching control calculation formula, the output angular frequency of the network-forming converter is calculated to update the phase reference value of the converter output voltage according to the output angular frequency.

[0009] Preferably, the improved matching control calculation formula is specifically:

[0010]

[0011] wherein, is a reference value of the DC bus voltage, is an actual measured value of the DC bus voltage, ω n is a reference angular frequency, k pdc is a proportional gain of a proportional-integral controller in the matching control, k idc is an integral gain in the matching control, s is a Laplace operator of the proportional-integral controller in the matching control, is the virtual power angle, is a reference value of the virtual power angle, ω is an output angular frequency of the grid-forming converter, is a virtual power angle coefficient.

[0012] Preferably, the calculation formula of the reference value of the virtual power angle is:

[0013]

[0014] wherein, is the reference value of the virtual power angle, is an active power reference value of the grid-forming converter, is a rated voltage amplitude, is a virtual reactance.

[0015] Preferably, the obtaining of the common connection point voltage phase and the converter output voltage phase of the grid-forming converter comprises:

[0016] obtaining the common connection point voltage phase through a phase-locked loop;

[0017] obtaining the converter output voltage phase under a standard matching control logic.

[0018] Preferably, the expression of the phase-locked loop is:

[0019]

[0020] wherein, is the common connection point voltage phase, k ppll is a proportional parameter of a PI loop of the phase-locked loop, k ipll is an integral parameter of a loop of the phase-locked loop, ω n is a reference angular frequency, s is a Laplace operator of a proportional-integral controller, is a q-axis component of the common connection point voltage in a two-phase synchronous rotating DC dq coordinate system.

[0021] Preferably, the expression of the standard matching control logic is:

[0022]

[0023] wherein, is a reference value of a DC bus voltage, is an actual measured value of the DC bus voltage, ω n is a reference angular frequency, k pdc is a proportional gain of a proportional-integral controller in the matching control, k idc is an integral gain in the matching control, θ ref is a phase reference value of a converter output voltage, s is a Laplace operator of the proportional-integral controller.

[0024] The second aspect of the present application provides a network configuration type converter transient stability enhancement control device, comprising:

[0025] a voltage phase acquisition unit, configured to acquire a point of common coupling voltage phase and a converter output voltage phase of the network configuration type converter;

[0026] a virtual power angle determination unit, configured to calculate a phase difference between the converter output voltage phase and the point of common coupling voltage phase, and determine a virtual power angle according to the phase difference;

[0027] an output angular frequency calculation unit, configured to calculate an output angular frequency of the network configuration type converter according to a difference between the virtual power angle and a virtual power angle reference value, in combination with a preset improved matching control calculation formula, so as to update a phase reference value of a converter output voltage according to the output angular frequency.

[0028] Preferably, the improved matching control calculation formula is specifically:

[0029]

[0030] wherein, is a reference value of a DC bus voltage, is an actual measured value of the DC bus voltage, ω n is a reference angular frequency, k pdc is a proportional gain of a proportional-integral controller in the matching control, k idc is an integral gain in the matching control, s is a Laplace operator of the proportional-integral controller in the matching control, is the virtual power angle, is the virtual power angle reference value, ω is an output angular frequency of the network configuration type converter, is a virtual power angle coefficient;

[0031] the calculation formula of the virtual power angle reference value is:

[0032]

[0033] wherein, a virtual power angle reference value, an active power reference value of the grid-forming converter, a rated voltage amplitude, a virtual reactance.

[0034] The third aspect of the present application provides a grid-forming converter transient stability enhancement control terminal, comprising a memory and a processor.

[0035] The memory is used to store program code corresponding to the grid-forming converter transient stability enhancement control method provided in the first aspect of the present application.

[0036] The processor is used to read and execute the program code to realize the grid-forming converter transient stability enhancement control method.

[0037] The fourth aspect of the present application provides a computer readable storage medium, which stores program code for being read and executed by a processor to realize the grid-forming converter transient stability enhancement control method provided in the first aspect of the present application.

[0038] From the above technical solutions, the present application has the following advantages:

[0039] The present application introduces a virtual power angle difference value as an additional control variable, so that the converter can respond to DC voltage fluctuations and power angle deviation at the same time, thereby enabling the output angular frequency of the grid-forming converter to quickly respond to phase jumps when the power grid experiences phase jumps or power fluctuations, and further enhancing the stability of the DC bus voltage, suppressing power angle oscillation and voltage instability during the transient process, and improving the dynamic synchronization capability of the grid-forming converter. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0041] Figure 1 It is a whole control block diagram of the grid-forming converter based on matching control.

[0042] Figure 2 It is a control block diagram of standard matching control.

[0043] Figure 3 It is a flowchart of an embodiment of the grid-forming converter transient stability enhancement control method provided by the present application.

[0044] Figure 4 This is a control block diagram of an improved matching control method for transient stability enhancement control of a grid-type converter based on the present application.

[0045] Figure 5 This is a block diagram of a phase-locked loop (PLL) control.

[0046] Figure 6 This is a schematic diagram of the architecture of an embodiment of a grid-type converter transient stability enhancement control device provided in this application.

[0047] Figure 7 This is a schematic diagram of the architecture of an embodiment of a grid-type converter transient stability enhancement control terminal provided in this application. Detailed Implementation

[0048] Matching control-based grid-type converters are commonly used in photovoltaic and wind power generation applications where DC bus voltage control is required. The overall control block diagram of a matching control-based grid-type converter is shown below. Figure 1 As shown. Where PWM (Pulse Width Modulation) represents pulse width modulation; v gabc Indicates grid voltage; v abc Indicates the output voltage at the point of common coupling; i Labc Indicates the output current on the converter side; i abc Indicates the output current on the grid side; L g This represents the line inductance. The converter uses an LC filter to filter out switching harmonics generated by the power electronic switching devices, where L... f and C f These represent the filter inductor and filter capacitor, respectively. In matching control, the dynamics of the DC bus voltage need to be considered, as shown in the diagram (V). dc P represents the DC bus capacitor voltage; dc P represents the constant power input to the DC bus; in Indicates the power of a DC bus input grid-type converter; i dc C represents the DC bus capacitor current; dc This represents the DC bus capacitance; while R dc This represents the parasitic resistance of the DC bus capacitor. (V) dcr This represents the DC bus voltage. Matching control (MC) achieves synchronization with the power grid by establishing a matching relationship between the DC bus voltage and the output angular frequency of the grid-connected converter. A standard matching control block diagram is shown below. Figure 2 As shown.

[0049] In existing technologies, grid-connected converters support grid voltage and frequency by simulating the characteristics of synchronous generators. Traditional matching control strategies rely on adjusting the output angular frequency based on the DC bus voltage to achieve grid synchronization. However, when the grid experiences phase jump disturbances, traditional methods are prone to transient instability and DC voltage fluctuations due to insufficient dynamic response, leading to decreased system stability. For example, in scenarios where renewable energy generation equipment is connected to a weak grid, phase jumps may occur frequently, and existing control logic struggles to quickly adjust the converter output phase, causing synchronization failure.

[0050] To address the aforementioned issues, the inventors discovered that traditional matching control relies solely on DC bus voltage feedback, lacking the ability to actively adjust for dynamic changes in grid phase. Therefore, this application provides a transient stability enhancement control method, device, terminal, and medium for grid-connected converters. This solution analyzes the power angle stabilization mechanism of synchronous generators, proposes converting the phase difference between the converter output voltage and the grid voltage into a virtual power angle, and designs a dynamic adjustment strategy based on this parameter. Furthermore, by combining an improved matching control calculation formula, the virtual power angle deviation is introduced into the angular frequency adjustment stage, thereby achieving a rapid response to phase jumps. This solves the technical problem of poor stability in existing matched-control grid-connected converters when facing grid phase jump disturbances.

[0051] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0052] Please see Figure 3 This application provides an embodiment of a transient stability enhancement control method for a grid-type converter, the steps of which include:

[0053] Step 101: Obtain the phase of the common coupling point voltage and the phase of the converter output voltage of the grid-type converter;

[0054] Step 102: Calculate the phase difference between the converter output voltage phase and the point of common coupling voltage phase, and determine the virtual power angle based on the phase difference;

[0055] Step 103: Based on the difference between the virtual power angle and the virtual power angle reference value, and combined with the preset improved matching control calculation formula, calculate the output angular frequency of the grid-type converter, and update the phase reference value of the converter output voltage according to the output angular frequency.

[0056] In this context, the point of common coupling voltage phase refers to the node voltage phase where the converter is connected to the grid, and the converter output voltage phase refers to the phase of the AC output voltage of the converter. The virtual power angle is the dynamic difference between the converter output voltage phase and the grid voltage phase; its function is to simulate the power angle characteristics of a synchronous generator, reflecting changes in the system's synchronization state. The improved matching control formula is a composite control equation that combines the virtual power angle deviation with DC bus voltage regulation. For example, it superimposes a virtual power angle deviation term onto traditional proportional-integral control, thereby simultaneously adjusting the angular frequency and phase reference value during phase abrupt changes, enhancing dynamic stability.

[0057] Specifically, the phase θ of the voltage at the point of common coupling is first measured in real time using a phase-locked loop. pll Simultaneously, the initial output voltage phase θ of the converter is generated based on the standard matching control logic. ref The virtual power angle is obtained by calculating the phase difference between the two. This parameter reflects the synchronization status between the converter and the power grid. The virtual power angle is then compared with a reference value, and the difference is input into the improved matching control formula, which, combined with the DC bus voltage deviation, generates the output angular frequency. This angular frequency is further integrated to update the phase reference value, forming a closed-loop regulation. For example, when a sudden change in the grid phase causes the virtual power angle to increase, the control formula accelerates phase adjustment by increasing the output angular frequency, allowing the virtual power angle to quickly converge to the reference value and avoiding loss of synchronization.

[0058] Traditional matching control requires AC disturbances to be transmitted to the DC side before it can react and adjust accordingly. This solution, however, introduces a virtual power angle dynamic feedback mechanism, directly incorporating the phase difference into the control loop. Based on the equal area criterion, increasing transient damping effectively reduces the acceleration area and increases the deceleration area, thereby enhancing the converter's transient stability. This allows the converter to proactively respond to grid phase changes, accelerating the response speed to AC disturbances after phase jumps and improving dynamic recovery speed. For example, under the same phase jump conditions, traditional methods may cause loss of synchronization due to accumulated phase differences. This solution, through real-time compensation of virtual power angle deviation, shortens the phase synchronization time. Through these technical solutions, this application can effectively suppress transient instability caused by grid phase jumps and improve the dynamic synchronization capability of grid-connected converters. For example, in weak grids or scenarios with a high proportion of renewable energy integration, the converter can quickly adjust its output phase to maintain stable synchronization with the grid, avoiding DC bus voltage fluctuations and system collapse risks.

[0059] Furthermore, the improved matching control calculation formula mentioned in the above embodiments is specifically as follows:

[0060]

[0061] In the formula, This is a reference value for the DC bus voltage. The actual measured value of the DC bus voltage, ω n As the reference angular frequency, k pdc To match the proportional gain of the proportional-integral controller in the control, k idc To represent the integral gain in matched control, s is the Laplace operator of the proportional-integral controller in matched control. For virtual power angle, Here, ω is the virtual power angle reference value, and ω is the output angular frequency of the grid-type converter. This is the virtual power angle coefficient.

[0062] Specifically, the improved matching control calculation formula uses the virtual power angle difference ( This introduces a DC voltage error regulation stage into the traditional matched control, forming a composite control signal. When a phase jump occurs in the power grid, the virtual power angle difference can quickly reflect the power angle offset between the converter and the grid. This difference signal, together with the DC voltage error signal, acts on the proportional-integral controller to generate the output angular frequency. The adjustment amount. The output angular frequency ω is then updated to the phase reference value of the converter output voltage through integration, thereby actively adjusting the power angle dynamics to enhance synchronization stability while suppressing DC bus voltage fluctuations.

[0063] This scheme introduces a virtual power angle difference as an additional control variable, enabling the converter to simultaneously respond to DC voltage fluctuations and power angle offsets. This achieves faster dynamic synchronization and more stable DC voltage regulation under phase jump disturbances. For a detailed control block diagram, please refer to [reference needed]. Figure 4 Through the above technical solutions, this application can effectively suppress the continuous shift of the virtual power angle under the grid phase jump disturbance, avoid the DC voltage collapse problem caused by the power angle loss of synchronization, and improve the synchronization capability of the converter in the transient process through the composite control strategy, thus significantly enhancing the transient stability of the grid-type converter.

[0064] Furthermore, the calculation formula for the virtual power angle reference value mentioned in the above embodiments is as follows:

[0065]

[0066] In the formula, This is a virtual power angle reference value. This is the active power reference value for grid-type converters. This is the rated voltage amplitude. This is a virtual reactance.

[0067] The virtual power angle reference value is a benchmark used for comparison with the actual virtual power angle value. Specifically, it can be calculated as the ratio of the active power reference value and the rated voltage amplitude. For example, the active power reference value can be the target power value set by the host computer, and the rated voltage amplitude can be the nominal voltage on the converter output side. Through this calculation formula, the virtual power angle reference value can be dynamically adjusted according to the active power demand, thereby adapting to the control requirements under different operating conditions. This takes into account the converter output voltage amplitude E and the point of common coupling voltage amplitude V. pcc All are equal to the rated voltage amplitude V N The variable relationships allow us to derive the virtual power angle reference value from the active power reference value.

[0068] This solution simplifies the calculation logic by directly linking the active power reference value and the virtual power angle reference value, while improving the dynamic response capability of the reference value. For example, when there are sudden phase changes in the power grid, the reference value can be quickly adjusted based on changes in active power, avoiding transient instability caused by reference value lag. Through the above technical solution, this application can enable the output angular frequency of the grid-connected converter to respond quickly by dynamically adjusting the virtual power angle reference value when the power grid experiences phase jumps or power fluctuations, thereby enhancing the stability of the DC bus voltage and suppressing power angle oscillations and voltage instability during transient processes. For example, in the scenario of grid connection of new energy power generation systems, this solution can effectively reduce the risk of converter disconnection caused by grid disturbances.

[0069] Furthermore, regarding step 101 in the above embodiments, this application proposes a specific implementation process for this step, which specifically includes:

[0070] The phase of the voltage at the point of common coupling is obtained through a phase-locked loop;

[0071] Obtain the phase of the converter output voltage under the standard matching control logic.

[0072] Among them, a phase-locked loop (PLL) refers to a closed-loop control system used to track the phase of the voltage at the point of common coupling. Specifically, it can be implemented using a digital PLL or a phase tracking module based on software algorithms. Its logic block diagram is shown below. Figure 5 As shown, its function is to capture the phase change of the grid voltage in real time, providing an accurate input signal for subsequent virtual power angle calculation.

[0073] The converter output voltage phase under standard matching control logic refers to the phase reference value generation method based on DC bus voltage regulation, and its logic block diagram is as follows: Figure 2 As shown, the DC bus voltage deviation can be adjusted by a proportional-integral controller to generate a phase reference value synchronized with the power grid. Its function is to maintain the stability of the DC bus voltage and ensure that the converter output operates synchronously with the power grid.

[0074] Specifically, the phase of the point of common coupling voltage is measured in real time using a phase-locked loop (PLL). For example, a PLL algorithm containing proportional-integral (PI) components can be used. By adjusting the proportional and integral parameters, the phase fluctuations of the grid voltage can be quickly tracked. The calculation formula can be found in the following example:

[0075] .

[0076] In the formula, k represents the voltage phase at the common junction point. ppll k is the proportional parameter of the pi element in the phase-locked loop. ipll Let ω be the integral parameter of the phase-locked loop (PLL) element. n Let be the reference angular frequency, and s be the Laplace operator of the proportional-integral controller. The common point of connection voltage is represented by the q-axis component in a two-phase synchronously rotating DC dq coordinate system.

[0077] The converter output voltage phase is generated through standard matching control logic. For example, based on the deviation between the actual DC bus voltage and the reference value, a phase reference value is obtained through proportional-integral calculation, which then drives the converter to output a voltage waveform synchronized with the grid. The calculation formula can be found in the following example:

[0078]

[0079] In the formula, This is a reference value for the DC bus voltage, while The actual measured value of the DC bus voltage is used. To prevent the DC voltage setpoint from affecting the dynamic response characteristics of the grid-type converter, this embodiment employs an energy-based voltage square control method. ω n As the reference angular frequency, k pdc To match the proportional gain of the proportional-integral controller in the control, k idc To match the integral gain of the proportional-integral controller in the control, θ ref is the phase reference value of the converter output voltage, and s is the Laplace operator of the proportional-integral controller.

[0080] By simultaneously acquiring the phase of the voltage at the point of common coupling and the phase of the converter output voltage, the phase difference between the two is used to calculate the virtual power angle, thereby providing basic data for subsequent transient stability control.

[0081] This solution directly measures the voltage phase at the point of common coupling (PCC) using a phase-locked loop (PLL) and combines this with the converter output voltage phase generated by standard matching control logic. This more accurately reflects the dynamic relationship between the actual grid conditions and the converter output, thereby reducing the impact of phase errors on virtual power angle calculations. Through this technical solution, this application effectively improves the transient stability of grid-connected converters under grid phase jump disturbances. By accurately acquiring the PCC voltage phase and converter output voltage phase, it avoids virtual power angle calculation deviations caused by phase tracking delays or errors, thus suppressing DC bus voltage instability and system oscillations.

[0082] This application proposes a transient stability enhancement control strategy for grid-connected converters based on virtual power angle. Introducing a virtual power angle into the matched control increases transient damping, thereby improving the transient stability of the grid-connected converter. Simultaneously, the virtual power angle accelerates the dynamic recovery speed of the power angle after grid phase jump disturbances. Therefore, the converter's output power can quickly recover to a stable value after a grid phase jump disturbance, thus avoiding potential DC bus undervoltage and overvoltage phenomena. This method balances the transient stability and DC voltage stability of the grid-connected converter under grid phase jump disturbances, and can be applied online and used when the converter is operating in maximum power point tracking scenarios. It is simple to implement without increasing hardware costs and effectively reduces the risk of system instability due to disturbances.

[0083] The above is a detailed description of an embodiment of a transient stability enhancement control method for a grid-type converter provided in this application. The following is a detailed description of related embodiments of a transient stability enhancement control device, terminal, and readable storage medium for a grid-type converter provided in this application.

[0084] Please see Figure 6 This application provides an embodiment of a transient stability enhancement control device for a grid-type converter, which mainly includes:

[0085] The voltage phase acquisition unit 201 is used to acquire the voltage phase at the common connection point of the grid converter and the output voltage phase of the converter.

[0086] The virtual power angle determination unit 202 is used to calculate the phase difference between the converter output voltage phase and the point of common coupling voltage phase, and determine the virtual power angle based on the phase difference;

[0087] The output angular frequency calculation unit 203 is used to calculate the output angular frequency of the grid-type converter based on the difference between the virtual power angle and the virtual power angle reference value, combined with the preset improved matching control calculation formula, so as to update the phase reference value of the converter output voltage according to the output angular frequency.

[0088] More specifically, the improved matching control calculation formula is as follows:

[0089]

[0090] In the formula, This is a reference value for the DC bus voltage. The actual measured value of the DC bus voltage, ω n As the reference angular frequency, k pdc To match the proportional gain of the proportional-integral controller in the control, k idc To represent the integral gain in matched control, s is the Laplace operator of the proportional-integral controller in matched control. For virtual power angle, Here, ω is the virtual power angle reference value, and ω is the output angular frequency of the grid-type converter. This is the virtual power angle coefficient;

[0091] The formula for calculating the virtual power angle reference value is:

[0092]

[0093] In the formula, This is a virtual power angle reference value. This is the active power reference value for grid-type converters. This is the rated voltage amplitude. This is a virtual reactance.

[0094] Specifically, the voltage phase acquisition unit tracks the phase information of the grid's point of common coupling voltage in real time through a phase-locked loop, and simultaneously acquires the phase of the converter's current output voltage through standard matching control logic. The virtual power angle determination unit performs a difference calculation on the two phase signals, and after filtering, generates a virtual power angle parameter characterizing the system's synchronization state. The output angular frequency calculation unit inputs the deviation between the virtual power angle and its reference value into the improved matching control formula, and generates an angular frequency adjustment amount through proportional-integral calculation. This adjustment amount is applied to the converter's pulse width modulation module to dynamically correct the output voltage's phase reference value, thereby quickly restoring synchronization when a phase jump occurs in the grid.

[0095] This solution introduces a virtual power angle feedback mechanism to construct a three-level closed-loop control architecture of phase difference, power angle, and frequency. This architecture can directly sense sudden phase changes in the power grid and generate corresponding frequency compensation signals. For example, when the grid voltage phase undergoes a step change, the virtual power angle determination unit can quickly detect the phase deviation, while the output angular frequency calculation unit generates a frequency regulation quantity with inertial characteristics through an improved matching control formula, avoiding the regulation lag problem caused by single voltage feedback in traditional methods. Through the above technical solution, this application can effectively suppress transient instability caused by grid phase jumps. The voltage phase acquisition unit achieves accurate synchronous measurement of the grid and converter phases, the virtual power angle determination unit establishes a quantitative index of system dynamic stability, and the output angular frequency calculation unit achieves dynamic damping characteristics of frequency regulation through an improved control algorithm. The coordinated operation of these three components enables the device to maintain DC bus voltage stability under grid disturbances, while avoiding continuous oscillations between the output phase and the grid phase, thereby improving the operational reliability of the grid-type converter under weak grid conditions.

[0096] Furthermore, such as Figure 7 As shown, the embodiment of the transient stability enhancement control terminal for a grid-type converter proposed in this application mainly includes: a memory 33 and a processor 31, wherein the memory 33 and the processor 31 can be connected through a communication bus 34; the memory 33 is used to store program code, which corresponds to the transient stability enhancement control method for the grid-type converter; the processor 31 is used to read and execute the program code to implement the transient stability enhancement control method for the grid-type converter.

[0097] In this context, "memory" refers to the hardware device used to store program code, which can be implemented using flash memory, hard disk, or solid-state drive. Its function is to provide the processor with a set of executable instructions, ensuring that the logic of the control method can be fully invoked. "Processor" refers to the arithmetic unit used to execute the program code, which can be implemented using a microprocessor, digital signal processor, or application-specific integrated circuit (ASIC). Its function is to calculate the output angular frequency and update the phase reference value in real time by running the program code, thereby achieving dynamic adjustment of the converter's output voltage. "Program code" refers to the set of computer instructions containing the steps of the transient stability enhancement control method for grid-type converters. Specifically, it can include logic for obtaining the voltage phase at the point of common coupling, calculating the virtual power angle difference, and generating the output angular frequency by combining the improved matching control formula. Its function is to translate the control algorithm into executable machine instructions, ensuring that the terminal can automatically complete the transient stability enhancement control.

[0098] Specifically, the program code stored in the memory contains instructions to obtain the phase of the point of common coupling voltage and the phase of the converter output voltage. It monitors the grid voltage phase in real time via a phase-locked loop and generates an initial phase reference value based on standard matching control logic. When the processor executes the program code, it first calculates the difference between the converter output voltage phase and the point of common coupling voltage phase to determine the virtual power angle. Then, based on the deviation between the virtual power angle and the reference value, and combined with the proportional-integral (PI) regulation mechanism in the improved matching control formula, it dynamically adjusts the output angular frequency and finally updates the phase reference value to enhance the transient stability of the converter. For example, the DC bus voltage error feedback and virtual power angle difference compensation introduced in the improved matching control formula can be processed in real time through the mathematical operation module in the program code, ensuring a rapid response from the terminal when the grid phase changes.

[0099] In some specific implementations, the memory can employ non-volatile storage media, such as EEPROM or NOR flash memory, to ensure that the program code is retained after power failure. The processor can integrate a multi-core architecture, such as using an ARM Cortex-M series microcontroller, to enhance parallel computing capabilities. The program code can be modularly designed into a data acquisition module, an algorithm calculation module, and an output control module, wherein the algorithm calculation module further includes a phase-locked loop calculation unit, a virtual power angle difference calculation unit, and a proportional-integral adjustment unit.

[0100] Furthermore, this application also proposes a computer-readable storage medium embodiment, wherein program code is stored therein, the program code being read and executed by a processor to implement a transient stability enhancement control method for a grid-type converter. The method includes obtaining the phase of the voltage at the point of common coupling and the phase of the converter output voltage, calculating the phase difference between the two to determine the virtual power angle, obtaining the output angular frequency based on the difference between the virtual power angle and the reference value combined with the improved matching control formula, and updating the phase reference value.

[0101] Computer-readable storage media refers to physical carriers capable of long-term storage of program code, such as solid-state drives, flash memory chips, or optical discs. Its function is to provide repeatedly readable code storage support for the execution of control methods. Program code refers to a set of code containing computer instructions, which can be written in C, Python, or assembly language. Its function is to transform the logic of the control method into a sequence of instructions that can be parsed and executed by the processor. The processor is an integrated circuit with computation and control functions, such as a central processing unit, digital signal processor, or microcontroller. Its function is to read and execute the program code in the storage medium to perform operations such as voltage phase acquisition, virtual power angle calculation, and output angular frequency adjustment.

[0102] Specifically, when the program code is executed by the processor, it first acquires the phase of the point of common coupling voltage through a phase-locked loop (PLL) and simultaneously acquires the phase of the converter output voltage under standard matching control logic. Then, it calculates the phase difference between the two to determine the virtual power angle and compares this virtual power angle with a reference value. This difference is input into the improved matching control formula and, combined with the deviation between the DC bus voltage reference value and the actual value, generates the output angular frequency through proportional-integral (PI) regulation. Finally, the output angular frequency is used to update the phase reference value of the converter output voltage, forming a closed-loop control. Throughout this process, the program code optimizes the algorithm logic to ensure the real-time performance and accuracy of phase adjustment.

[0103] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the terminals, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0104] In the several embodiments provided in this application, it should be understood that the disclosed terminals, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between devices or units, and may be electrical, mechanical, or other forms.

[0105] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0106] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0107] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0108] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0109] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0110] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A transient stability enhancement control method for a grid-type converter, characterized in that, include: Obtain the phase of the common coupling voltage and the phase of the converter output voltage of the grid-type converter; Calculate the phase difference between the converter output voltage phase and the common coupling point voltage phase, and determine the virtual power angle based on the phase difference; Based on the difference between the virtual power angle and the virtual power angle reference value, and combined with the preset improved matching control calculation formula, the output angular frequency of the grid-type converter is calculated, so as to update the phase reference value of the converter output voltage according to the output angular frequency.

2. The transient stability enhancement control method for a grid-type converter according to claim 1, characterized in that, The improved matching control calculation formula is as follows: In the formula, This is a reference value for the DC bus voltage. The actual measured value of the DC bus voltage, ω n As the reference angular frequency, k pdc To match the proportional gain of the proportional-integral controller in the control, k idc To represent the integral gain in matched control, s is the Laplace operator of the proportional-integral controller in matched control. The virtual power angle, The virtual power angle reference value is ω, where ω is the output angular frequency of the grid-type converter. This is the virtual power angle coefficient.

3. The transient stability enhancement control method for a grid-type converter according to claim 1 or 2, characterized in that, The formula for calculating the virtual power angle reference value is: In the formula, The virtual power angle reference value, This is the active power reference value for the grid-type converter. This is the rated voltage amplitude. This is a virtual reactance.

4. The transient stability enhancement control method for a grid-type converter according to claim 1, characterized in that, The acquisition of the common coupling point voltage phase and the converter output voltage phase of the grid-type converter includes: The phase of the voltage at the point of common coupling is obtained through a phase-locked loop; Obtain the phase of the converter output voltage under the standard matching control logic.

5. The transient stability enhancement control method for a grid-type converter according to claim 4, characterized in that, The expression for the phase-locked loop is: In the formula, k represents the voltage phase at the common junction point. ppll k is the proportional parameter of the pi element in the phase-locked loop. ipll Let ω be the integral parameter of the phase-locked loop (PLL) element. n Let be the reference angular frequency, and s be the Laplace operator of the proportional-integral controller. The common point of connection voltage is represented by the q-axis component in a two-phase synchronously rotating DC dq coordinate system.

6. The transient stability enhancement control method for a grid-type converter according to claim 4, characterized in that, The expression for the standard matching control logic is: In the formula, This is a reference value for the DC bus voltage. The actual measured value of the DC bus voltage, ω n As the reference angular frequency, k pdc To match the proportional gain of the proportional-integral controller in the control, k idc To match the integral gain in the control, θ ref is the phase reference value of the converter output voltage, and s is the Laplace operator of the proportional-integral controller.

7. A transient stability enhancement control device for a grid-type converter, characterized in that, include: The voltage phase acquisition unit is used to acquire the voltage phase at the point of common coupling and the output voltage phase of the grid-type converter. The virtual power angle determination unit is used to calculate the phase difference between the output voltage phase of the converter and the voltage phase of the point of common coupling, and to determine the virtual power angle based on the phase difference; The output angular frequency calculation unit is used to calculate the output angular frequency of the grid-type converter based on the difference between the virtual power angle and the virtual power angle reference value, combined with a preset improved matching control calculation formula, so as to update the phase reference value of the converter output voltage according to the output angular frequency.

8. The transient stability enhancement control device for a grid-type converter according to claim 7, characterized in that, The improved matching control calculation formula is as follows: In the formula, This is a reference value for the DC bus voltage. The actual measured value of the DC bus voltage, ω n As the reference angular frequency, k pdc To match the proportional gain of the proportional-integral controller in the control, k idc To represent the integral gain in matched control, s is the Laplace operator of the proportional-integral controller in matched control. The virtual power angle, The virtual power angle reference value is ω, where ω is the output angular frequency of the grid-type converter. This is the virtual power angle coefficient; The formula for calculating the virtual power angle reference value is: In the formula, The virtual power angle reference value, This is the active power reference value for the grid-type converter. This is the rated voltage amplitude. This is a virtual reactance.

9. A transient stability enhancement control terminal for a grid-type converter, characterized in that, include: Memory and processor; The memory is used to store program code, which corresponds to the transient stability enhancement control method for grid-type converters as described in any one of claims 1 to 6; The processor is used to read and execute the program code to implement the transient stability enhancement control method for the grid-type converter.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains program code that is read and executed by a processor to implement the transient stability enhancement control method for grid-type converters as described in any one of claims 1 to 6.

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