Prewsychronization control method and device for grid-forming reactive power generator

Abstract

The application relates to a network-constructing type reactive generator pre-synchronization control method and device. The method comprises the following steps: after the network-constructing type reactive generator is connected with a power grid, acquiring three-phase alternating voltage values and power grid angular frequency values of the power grid, and acquiring an initial network-constructing phase angle and a network-constructing angular frequency value of the network-constructing type reactive generator; according to the three-phase alternating voltage values, the power grid angular frequency values, the initial network-constructing phase angle and the network-constructing angular frequency value, pre-synchronization processing is conducted on the network-constructing type reactive generator to obtain a network-constructing reference voltage; and the network-constructing type reactive generator is started according to the network-constructing reference voltage, so that the network-constructing type reactive generator is in a grid-connected operation state. By adopting the method, the network-constructing type reactive generator can be freed from phase-locked loop control, and small disturbance stability of the network-constructing type reactive generator is improved.

Description

Technical Field

[0001] This application relates to the field of grid-connected reactive power generator technology, and in particular to a pre-synchronization control method and device for a grid-connected reactive power generator. Background Technology

[0002] In recent years, the proportion of new energy power generation, represented by wind power and photovoltaic power, in the power grid has increased rapidly. To address scenarios such as new energy grid connection via DC and weak AC grid connection via asynchronous DC interconnection, flexible AC / DC topologies and control technologies, represented by modular multilevel converters, have developed rapidly. To ensure the smooth operation of various power electronic devices under weak grid conditions, various grid-based control methods have emerged. Static Var Generators (SVG) utilize power semiconductor bridge converters to achieve reactive power compensation, belonging to dynamic compensation devices. Through reactors, SVG connects its self-commutating bridge circuit directly or in parallel to the power supply system, and uses different control methods to control the phase and magnitude of the current transmitted to the power supply system to form reactive current, offsetting the current in the system and achieving tracking compensation for nonlinear loads. Currently, SVG is mainly grid-connected; grid-based SVG has not yet been widely applied to the grid. On the one hand, with the increasing proportion of new energy power generation, the power grid structure is also changing; on the other hand, with in-depth research on grid-based technologies, the production and deployment of grid-based SVG will inevitably be a future trend.

[0003] Traditional grid-connected reactive power generators (SGDs) are not only cumbersome in their startup procedures, but also cannot escape the phase-locked loop (PLL) control loop inherent in traditional grid-connected control. When grid strength is low, strong coupling exists between the PLL and the grid impedance, severely reducing the small-disturbance stability of the SGD. Therefore, how to eliminate PLL control from SGDs to improve their small-disturbance stability has become a pressing technical problem. Summary of the Invention

[0004] Therefore, it is necessary to provide a pre-synchronization control method and device for grid-type reactive power generators that can free grid-type reactive power generators from phase-locked loop control, thereby improving the small-disturbance stability of grid-type reactive power generators, in order to address the above-mentioned technical problems.

[0005] Firstly, this application provides a pre-synchronization control method for a grid-type reactive power generator, including:

[0006] After the grid-type reactive power generator is connected to the power grid, the three-phase AC voltage value and the grid angular frequency value of the power grid are obtained, as well as the initial grid-type phase angle and grid-type angular frequency value of the grid-type reactive power generator.

[0007] Based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle and the grid angular frequency value, the grid-type reactive power generator is pre-synchronized to obtain the grid reference voltage.

[0008] The grid-connected reactive power generator is started according to the grid reference voltage to put it into grid-connected operation.

[0009] In one embodiment, the grid-type reactive power generator undergoes pre-synchronization processing based on the three-phase AC voltage value, the grid angular frequency value, the initial grid-connection phase angle, and the grid-connection angular frequency value to obtain the grid-connection reference voltage, including:

[0010] Based on the three-phase AC voltage values ​​and the initial grid phase angle, the grid-type reactive power generator is phase synchronized to obtain the phase compensation angle.

[0011] Based on the grid angular frequency value and the network angular frequency value, frequency synchronization is performed on the network-type reactive power generator to obtain active power compensation data;

[0012] Based on the three-phase AC voltage values ​​and the initial grid phase angle, amplitude synchronization is performed on the grid-type reactive power generator to obtain the amplitude synchronization result;

[0013] The grid reference voltage is obtained based on the phase compensation angle, active power compensation data, and amplitude synchronization results.

[0014] In one embodiment, the grid reference voltage is obtained based on the phase compensation angle, active power compensation data, and amplitude synchronization results, including:

[0015] Virtual synchronization of the grid-type reactive power generator is performed based on active power compensation data to obtain the virtual synchronization result;

[0016] Determine the target network phase angle based on the virtual synchronization results and phase compensation angle;

[0017] Based on the target network phase angle, the amplitude synchronization result is subjected to Park inverse transformation to obtain the network reference voltage.

[0018] In one embodiment, virtual synchronization of the grid-type reactive power generator is performed based on active power compensation data, and the virtual synchronization results include:

[0019] Obtain the initial active power reference value, actual active power, and oscillation relationship of the virtual synchronous machine;

[0020] The initial active power reference value is corrected based on the active power compensation data to obtain the corrected active power reference value.

[0021] The power difference between the corrected active power reference value and the actual active power is determined. The network angular frequency value is updated based on the power difference and the swing relationship to obtain the updated network angular frequency value. The updated network angular frequency value is used as the virtual synchronization result.

[0022] In one embodiment, before performing an inverse Parker transform on the amplitude synchronization result based on the target network phase angle to obtain the network reference voltage, the above method includes:

[0023] If the phase angle of the target network meets the closing conditions, a closing permission signal is sent.

[0024] In one embodiment, the grid-type reactive power generator is phase-synchronized based on the three-phase AC voltage values ​​and the initial grid-connected phase angle to obtain the phase compensation angle, including:

[0025] Based on the initial network phase angle, Parker transformation is performed on the three-phase AC voltage values ​​to obtain the direct-axis and quadrature-axis components of the three-phase AC voltage values ​​in the rotating coordinate system.

[0026] Determine the angle between the direct axis component and the quadrature axis component;

[0027] Determine the angle difference between the included angle and the preset angle, and perform proportional integration on the angle difference to obtain the phase compensation angle.

[0028] In one embodiment, determining the angle between the direct axis component and the quadrature axis component includes:

[0029] Add positive and negative signs to the direct-axis components to obtain the labeled direct-axis components;

[0030] Determine the angle between the direct axis component and the quadrature axis component after adding the label.

[0031] In one embodiment, frequency synchronization is performed on the grid-type reactive power generator based on the grid angular frequency value and the grid-structure angular frequency value to obtain active power compensation data, including:

[0032] Determine the angular frequency difference between the power grid angular frequency value and the network construction angular frequency value;

[0033] The active power compensation data is obtained by performing proportional-integral calculation on the angular frequency difference.

[0034] In one embodiment, amplitude synchronization is performed on the grid-type reactive power generator based on the three-phase AC voltage value and the initial grid phase angle, and the amplitude synchronization results include:

[0035] Based on the initial network phase angle, Parker transformation is performed on the three-phase AC voltage values ​​to obtain the direct-axis and quadrature-axis components of the three-phase AC voltage values ​​in the rotating coordinate system.

[0036] Nonlinear filtering is performed on the direct-axis and quadrature-axis components to obtain the filtered direct-axis and quadrature-axis components. The filtered direct-axis and quadrature-axis components are then used as the amplitude synchronization results.

[0037] Secondly, this application also provides a pre-synchronization control device for a grid-type reactive power generator, comprising:

[0038] The data acquisition module is used to acquire the three-phase AC voltage value and grid angular frequency value of the grid after the grid-type reactive power generator is connected to the grid, as well as the initial grid-type phase angle and grid-type angular frequency value of the grid-type reactive power generator;

[0039] The pre-synchronization module is used to pre-synchronize the grid-type reactive power generator based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle, and the grid angular frequency value to obtain the grid reference voltage.

[0040] The startup module is used to start the grid-connected reactive power generator according to the grid reference voltage, so that the grid-connected reactive power generator is in grid-connected operation.

[0041] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0042] After the grid-type reactive power generator is connected to the power grid, the three-phase AC voltage value and the grid angular frequency value of the power grid are obtained, as well as the initial grid-type phase angle and grid-type angular frequency value of the grid-type reactive power generator.

[0043] Based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle and the grid angular frequency value, the grid-type reactive power generator is pre-synchronized to obtain the grid reference voltage.

[0044] The grid-connected reactive power generator is started according to the grid reference voltage to put it into grid-connected operation.

[0045] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0046] After the grid-type reactive power generator is connected to the power grid, the three-phase AC voltage value and the grid angular frequency value of the power grid are obtained, as well as the initial grid-type phase angle and grid-type angular frequency value of the grid-type reactive power generator.

[0047] Based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle and the grid angular frequency value, the grid-type reactive power generator is pre-synchronized to obtain the grid reference voltage.

[0048] The grid-connected reactive power generator is started according to the grid reference voltage to put it into grid-connected operation.

[0049] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0050] After the grid-type reactive power generator is connected to the power grid, the three-phase AC voltage value and the grid angular frequency value of the power grid are obtained, as well as the initial grid-type phase angle and grid-type angular frequency value of the grid-type reactive power generator.

[0051] Based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle and the grid angular frequency value, the grid-type reactive power generator is pre-synchronized to obtain the grid reference voltage.

[0052] The grid-connected reactive power generator is started according to the grid reference voltage to put it into grid-connected operation.

[0053] The aforementioned pre-synchronization control method, device, computer equipment, computer-readable storage medium, and computer program product for grid-type reactive power generators can, before startup, perform phase synchronization on the grid-type reactive power generator to avoid active power oscillations caused by phase differences, frequency synchronization to avoid loss of synchronization and system oscillations caused by frequency drift, and amplitude synchronization to avoid sudden changes in reactive power caused by voltage deviations. This achieves smooth, stable, and safe grid-connected operation, improves control accuracy, and extends the lifespan of the grid-type reactive power generator. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is a flowchart illustrating the pre-synchronization control method for a grid-type reactive power generator in one embodiment.

[0056] Figure 2 This is a block diagram of the pre-synchronization control of the controller in one embodiment;

[0057] Figure 3 This is a flowchart illustrating the process of pre-synchronizing a grid-type reactive power generator based on three-phase AC voltage values, grid angular frequency values, initial grid phase angle, and grid angular frequency values ​​to obtain the grid reference voltage in one embodiment.

[0058] Figure 4 This is a comparison diagram of the simulated waveform of the grid reference voltage before startup and the grid voltage waveform in one embodiment;

[0059] Figure 5 The following is a simulation waveform diagram of the grid reference voltage, grid voltage, and virtual synchronization output phase angle before and after a disturbance when the grid voltage jumps by 30° in one embodiment;

[0060] Figure 6 This is a flowchart illustrating the pre-synchronization control method for a grid-type reactive power generator in another embodiment;

[0061] Figure 7 This is a structural block diagram of a pre-synchronization control device for a grid-type reactive power generator in one embodiment;

[0062] Figure 8 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0064] In one exemplary embodiment, such as Figure 1 As shown, a pre-synchronization control method for a grid-type reactive power generator is provided. Taking the application of this method to the controller in a grid-type reactive power generator as an example, the method includes steps 102 to 106. Wherein:

[0065] Step 102: After the grid-type reactive power generator is connected to the power grid, obtain the three-phase AC voltage value and grid angular frequency value of the power grid, as well as the initial grid-type reactive power generator's grid-type phase angle and grid-type angular frequency value.

[0066] After the grid-connected reactive power generator is connected to the power grid, it acquires the three-phase AC voltage and grid angular frequency values ​​of the power grid, as well as the initial grid-connection phase angle and grid angular frequency values ​​of the generator. The initial grid-connection phase angle and grid angular frequency values ​​are automatically generated by the generator after grid connection. Grid connection refers to physical connection, meaning the generator is connected to the power grid lines via a grid-connected switch (grid-connected circuit breaker), but the circuit breaker remains open and no power is actually supplied. Thus, the controller in the generator can collect grid voltage signals, including the three-phase AC voltage and grid angular frequency values, but does not inject power into the grid.

[0067] Step 104: Based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle, and the grid angular frequency value, perform pre-synchronization processing on the grid-type reactive power generator to obtain the grid reference voltage.

[0068] Pre-synchronization processing refers to the synchronization process performed on the grid-connected reactive power generator before its startup. The grid reference voltage is a virtual voltage reference signal with the same frequency, phase, and amplitude as the grid voltage; it serves as reference data for grid alignment.

[0069] In some implementations, the grid-type reactive power generator is subjected to phase synchronization, frequency synchronization, amplitude synchronization, and virtual synchronization based on the three-phase AC voltage value, grid angular frequency value, initial grid phase angle, and grid angular frequency value, in order to achieve pre-synchronization processing and obtain the grid reference voltage.

[0070] Step 106: Start the grid-connected reactive power generator according to the grid reference voltage so that the grid-connected reactive power generator is in grid-connected operation.

[0071] Before obtaining the grid reference voltage, the grid-connected circuit breaker has already closed. Therefore, after obtaining the grid reference voltage, the grid reference voltage is directly coupled with the grid voltage, and power exchange begins to start, realizing true grid connection. At this time, the grid-connected reactive power generator is in grid-connected operation.

[0072] In the aforementioned pre-synchronization control method for grid-connected reactive power generators, the pre-synchronization function is automatically executed after the generator is connected to the grid, without the need for a separate control mode. Furthermore, pre-synchronization can be completed before the generator starts, allowing direct startup in grid-connected mode without the need for post-start mode switching between grid connection / connection or grid-connected / off-grid operation. This solves the problem of requiring phase-locked loop (PLL) control for grid-connected reactive power generators. Since the entire startup process of the grid-connected reactive power generator involves no mode switching, all changes are continuous, preventing system jumps and impacts.

[0073] In an exemplary embodiment, the pre-synchronization processing of the grid-type reactive power generator to obtain the grid reference voltage based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle, and the grid angular frequency value includes: performing phase synchronization on the grid-type reactive power generator based on the three-phase AC voltage value and the initial grid phase angle to obtain the phase compensation angle; performing frequency synchronization on the grid-type reactive power generator based on the grid angular frequency value and the grid angular frequency value to obtain active power compensation data; performing amplitude synchronization on the grid-type reactive power generator based on the three-phase AC voltage value and the initial grid phase angle to obtain the amplitude synchronization result; and obtaining the grid reference voltage based on the phase compensation angle, the active power compensation data, and the amplitude synchronization result.

[0074] Among them, the phase compensation angle refers to the data used to correct the phase synchronization error between the grid-type reactive power generator and the power grid. The active power compensation data refers to the adjustment amount or measurement data made to the active power deviation between the grid-type reactive power generator and the power grid during the synchronization process of the grid-type reactive power generator.

[0075] In some implementations, during the phase synchronization stage, the initial grid-connected phase angle is adjusted based on the three-phase AC voltage values ​​to obtain a phase compensation angle that synchronizes the grid-connected reactive power generator with the grid phase. During the frequency synchronization stage, the grid-connected angular frequency value is adjusted based on the grid angular frequency value to obtain active power compensation data that synchronizes the grid-connected reactive power generator with the grid frequency. During the amplitude synchronization stage, the initial grid-connected phase angle is adjusted based on the three-phase AC voltage values ​​to obtain an amplitude synchronization result that synchronizes the grid-connected reactive power generator with the grid amplitude. Finally, the grid-connected reference voltage is obtained based on the phase compensation angle, active power compensation data, and amplitude synchronization result.

[0076] In this embodiment, performing phase synchronization on the grid-type reactive power generator before startup can prevent active power oscillations caused by phase differences; performing frequency synchronization can prevent loss of synchronization and system oscillations caused by frequency drift; and performing amplitude synchronization can prevent sudden changes in reactive power caused by voltage deviations. This achieves smooth, stable, and safe grid-connected operation, improves control accuracy, and extends the lifespan of the grid-type reactive power generator.

[0077] In an exemplary embodiment, phase synchronization of the grid-type reactive power generator is performed based on the three-phase AC voltage values ​​and the initial grid-type phase angle to obtain the phase compensation angle. This includes: performing a Parker transformation on the three-phase AC voltage values ​​based on the initial grid-type phase angle to obtain the direct-axis and quadrature-axis components of the three-phase AC voltage values ​​in a rotating coordinate system; determining the angle between the direct-axis and quadrature-axis components; determining the angle difference between the angle and a preset angle; and performing a proportional-integral operation on the angle difference to obtain the phase compensation angle.

[0078] Among them, the direct axis component and quadrature axis component of the three-phase AC voltage value in the rotating coordinate system refer to the d-axis component and the q-axis component, respectively.

[0079] In some implementations, such as Figure 2 The diagram shown is a pre-synchronization control block diagram of the controller. In the phase synchronization stage, the phase angle of the initial network configuration is used... For the three-phase AC voltage value U ac Performing the Parker transformation (ABC-DQ transformation) yields the direct-axis components U of the three-phase AC voltage values ​​in the rotating coordinate system. d and cross-axis component U qThree-phase AC voltage values ​​include u a u b and u c The Parker transformation formula is shown below:

[0080]

[0081] Among them, u d u q u0 and u0 represent the direct-axis component, quadrature-axis component, and zero-sequence component, respectively. The zero-sequence component is used to reflect the three-phase imbalance / common-level drift.

[0082] The angle between the direct-axis and quadrature-axis components is determined using the arctangent function (atan). This angle represents the phase angle of the three-phase AC voltage value in a rotating coordinate system. The arctangent function is shown below:

[0083]

[0084] The angle difference between the included angle and the preset angle is determined, and the phase compensation angle is obtained by proportional-integral (PI) calculation of the angle difference. The preset angle refers to the phase angle when the grid-type reactive power generator is phase-synchronized with the power grid, such as 0°.

[0085] In this embodiment, the phase compensation angle is obtained by performing proportional-integral calculation on the angle difference between the included angle and the preset angle. This can quickly and accurately eliminate the phase error between the grid voltage and the output of the grid-type reactive power generator, achieve safe and smooth grid connection, avoid inrush current, and improve system stability and reliability.

[0086] In an exemplary embodiment, determining the angle between the direct axis component and the quadrature axis component includes: adding a positive or negative sign to the direct axis component to obtain the labeled direct axis component; and determining the angle between the labeled direct axis component and the quadrature axis component.

[0087] In some implementations, the angle between the direct-axis component and the quadrature-axis component ranges from 0 to 360 degrees. The limitation of the arctangent angle calculation formula of the phase synchronization element cannot identify 0° and 180°, meaning that it satisfies the condition when the angle is 0° or 180°. =0. When the included angle is 0°, U d =1, U q =0; when the included angle is 180°, U d =-1, U q =0, therefore we can know that it can be passed through U dThe sign of the three-phase AC voltage value is used to determine the angle between the three-phase AC voltage values ​​in the rotating coordinate system ([0, 180) or [180, 360)). Therefore, by adding a sign to the direct axis component, the marked direct axis component is obtained. Then, the angle between the marked direct axis component and the quadrature axis component is determined, which can accurately distinguish between 0° and 180°.

[0088] In this embodiment of the application, by capturing the sign of the direct axis component in the angle calculation, the problem of a 180° phase difference that may occur during synchronization due to algorithm defects is avoided, thus ensuring the correctness of synchronization. At the same time, the problem of voltage phase non-synchronization caused by the periodic jump variable of the control output is solved.

[0089] In an exemplary embodiment, frequency synchronization of the grid-type reactive power generator is performed based on the grid angular frequency value and the grid-structure angular frequency value to obtain active power compensation data, including: determining the angular frequency difference between the grid angular frequency value and the grid-structure angular frequency value; and performing proportional-integral calculation on the angular frequency difference to obtain active power compensation data.

[0090] In some implementations, such as Figure 2 As shown, in the frequency synchronization stage, the grid angular frequency value is calculated. Subtract the angular frequency value of the mesh The angular frequency difference is used. The active power compensation data P is obtained by performing a proportional-integral operation on the angular frequency difference using a PI converter. delta By adjusting the active power setting of the grid-type reactive power generator, the PF (active power - grid frequency) droop curve of the system is shifted, and the frequency error is compensated by power regulation, thereby achieving frequency consistency between the grid system and the grid.

[0091] In this embodiment, during the frequency synchronization stage, active power compensation data is obtained by performing proportional-integral calculation on the angular frequency difference between the grid angular frequency value and the network angular frequency value. This can eliminate steady-state frequency difference and ensure that the network frequency is consistent with the grid in the long term; it can quickly suppress disturbances (the proportional term provides instantaneous correction) and improve the stability of small disturbances; the frequency deviation is converted into active power correction to achieve synchronous machine-type frequency regulation coordination.

[0092] In one exemplary embodiment, such as Figure 3 As shown, based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle, and the grid angular frequency value, the grid-type reactive power generator undergoes pre-synchronization processing to obtain the grid reference voltage, including steps 302 to 312. Wherein:

[0093] Step 302: Based on the three-phase AC voltage values ​​and the initial grid-type reactive power generator, perform phase synchronization to obtain the phase compensation angle.

[0094] Step 304: Based on the grid angular frequency value and the network angular frequency value, perform frequency synchronization on the network-type reactive power generator to obtain active power compensation data.

[0095] Step 306: Based on the three-phase AC voltage values ​​and the initial grid phase angle, perform amplitude synchronization on the grid-type reactive power generator to obtain the amplitude synchronization result.

[0096] Step 308: Perform virtual synchronization on the grid-type reactive power generator based on the active power compensation data to obtain the virtual synchronization result.

[0097] Step 310: Determine the target network phase angle based on the virtual synchronization result and the phase compensation angle.

[0098] Step 312: Perform Parker inverse transformation on the amplitude synchronization result based on the target network phase angle to obtain the network reference voltage.

[0099] Virtual synchronization refers to simulating the dynamic characteristics of a virtual synchronizer. The target network phase angle refers to the network phase angle obtained by updating the initial network phase angle.

[0100] In some implementations, such as Figure 2 As shown, the pre-synchronization process also includes a virtual synchronization stage. In the virtual synchronization stage, based on the active power compensation data P... delta Virtual synchronization is performed on the grid-type reactive power generator to obtain the virtual synchronization result. Then, the virtual synchronization result is integrated using an integrator (1 / s) to convert it into a corresponding virtual phase angle. Based on the sum of the virtual phase angle and the phase compensation angle, the target grid-type phase angle is determined. Based on the target grid phase angle, the amplitude synchronization result is subjected to an inverse Parker transform (DQ-ABC) to obtain the grid reference voltage. The formula for the inverse Parker transform is shown below:

[0101]

[0102] In this embodiment, the grid-type reactive power generator is virtually synchronized based on active power compensation data, giving it the dynamic characteristics of a virtual synchronous machine, rather than simple phase-locked loop tracking. Virtual synchronization alone may result in a small steady-state error between the output grid phase and the grid phase. Phase compensation angles can correct the virtual synchronization result, ensuring precise alignment of the final reference phase with the grid. This embodiment utilizes frequency synchronization followed by phase angle compensation to jointly adjust the phase angle generated by the virtual synchronization stage, enabling faster phase synchronization.

[0103] In an exemplary embodiment, virtual synchronization of the grid-type reactive power generator is performed based on active power compensation data to obtain the virtual synchronization result, which includes: acquiring the initial active power reference value, actual active power, and oscillation relationship of the virtual synchronizer; correcting the initial active power reference value based on the active power compensation data to obtain the corrected active power reference value; determining the power difference between the corrected active power reference value and the actual active power; updating the grid angular frequency value based on the power difference and oscillation relationship to obtain the updated grid angular frequency value; and using the updated grid angular frequency value as the virtual synchronization result.

[0104] In some formulas, such as Figure 2 As shown, in the virtual synchronization stage, the initial active power reference value P of the virtual synchronizer is obtained. ref Actual active power P e And the relationship of oscillation ( =P ref *-P e Where J represents the moment of inertia (unit inertia coefficient), indicating the slowness of rotor acceleration / deceleration, and D represents the damping coefficient, indicating the damping torque at frequency deviation.

[0105] Based on the sum of the active power compensation data and the initial active power reference value, the corrected active power reference value P is obtained. ref * Determine the power difference between the corrected active power reference value and the actual active power. Update the network angular frequency value based on the power difference and the oscillation relationship to obtain the updated network angular frequency value. Use the updated network angular frequency value as the virtual synchronization result.

[0106] In this embodiment, the network angular frequency value is updated based on the swing relationship of the virtual synchronizer and the active power compensation data. Inertia and damping characteristics are introduced, which can generate a dynamically stable network angular velocity and phase.

[0107] In an exemplary embodiment, before performing a Parker inverse transform on the amplitude synchronization result based on the target network phase angle to obtain the network reference voltage, the above method includes: sending a closing permission signal if the target network phase angle meets the closing conditions.

[0108] After obtaining the target grid-connected phase angle, it is determined whether the target grid-connected phase angle meets the closing conditions. The closing conditions can be that the deviation between the target grid-connected phase angle and the grid phase angle meets a preset threshold. If the closing conditions are met, a closing permission signal is sent to the grid-connected circuit breaker, and the target grid-connected phase angle is updated to the initial grid-connected phase angle. If the closing conditions are not met, the process can return to the steps of pre-synchronizing the grid-connected reactive power generator based on the three-phase AC voltage value, grid angular frequency value, initial grid-connected phase angle, and grid angular frequency value until the closing conditions are met. Upon receiving the closing permission signal, the grid-connected circuit breaker closes. Subsequently, the grid-connected reactive power generator can be started according to the grid reference voltage to put it into grid-connected operation.

[0109] In this embodiment, when the target grid phase angle meets the closing conditions, a closing permission signal is sent, which can ensure that the voltage amplitude, frequency and phase of the grid-type reactive power generator are consistent with the grid during the grid connection closing process, thereby achieving shock-free grid connection. This method avoids the discontinuity caused by large current impact and mode switching, improves the safety and smoothness of grid connection operation, and further enhances the stability of the system under small disturbances under weak grid conditions.

[0110] In an exemplary embodiment, amplitude synchronization is performed on the grid-type reactive power generator based on the three-phase AC voltage values ​​and the initial grid phase angle. The amplitude synchronization result includes: performing a Parker transformation on the three-phase AC voltage values ​​based on the initial grid phase angle to obtain the direct-axis and quadrature-axis components of the three-phase AC voltage values ​​in a rotating coordinate system; performing nonlinear filtering on the direct-axis and quadrature-axis components to obtain the filtered direct-axis and quadrature-axis components; and using the filtered direct-axis and quadrature-axis components as the amplitude synchronization result.

[0111] In some implementations, such as Figure 2 As shown, in the amplitude synchronization stage, U d and U q The calculation process is consistent with the phase synchronization process. The potential impact of grid voltage fluctuations is taken into account. U... d and U q After nonlinear filtering, the filtered direct-axis component and the filtered quadrature-axis component (Udq) are obtained, which are used as the input reference voltage to ensure the synchronization of the power grid amplitude. The nonlinear filtering formula is as follows:

[0112]

[0113] The parameters of the nonlinear filtering formula can be set according to different application scenarios. For example, k1 and k2 can be set to 0.9 and 0.3, respectively.

[0114] In this embodiment, by performing nonlinear filtering on the direct-axis and quadrature-axis components of the three-phase AC voltage values ​​in the rotating coordinate system during the amplitude synchronization stage, grid noise and harmonics can be suppressed, ensuring amplitude stability.

[0115] The pre-synchronization control method for the above-mentioned grid-type reactive power generator is verified and implemented in MATLAB simulation. Figure 4 The comparison between the simulated reference voltage waveform before grid connection and the grid voltage waveform shows that the three-phase voltage synchronization between the two is relatively high. Figure 5 The simulation waveforms of the grid reference voltage, grid voltage, and virtual synchronous output phase angle before and after a disturbance with a 30° grid voltage jump are shown. It can be seen that the three-phase voltages remain synchronized after the disturbance, which plays a good role in reducing startup fluctuations.

[0116] In another exemplary embodiment, such as Figure 6 As shown, a pre-synchronization control method for a grid-type reactive power generator is provided, including:

[0117] Step 602: After the grid-type reactive power generator is connected to the power grid, obtain the three-phase AC voltage value and grid angular frequency value of the power grid, as well as the initial grid-type reactive power generator's grid-type phase angle and grid-type angular frequency value.

[0118] Step 604: Perform Parker transformation on the three-phase AC voltage values ​​based on the initial network phase angle to obtain the direct-axis and quadrature-axis components of the three-phase AC voltage values ​​in the rotating coordinate system; add positive and negative signs to the direct-axis components to obtain the labeled direct-axis components; determine the angle between the labeled direct-axis components and the quadrature-axis components; determine the angle difference between the angle and the preset angle, and perform proportional-integral calculation on the angle difference to obtain the phase compensation angle. Continue to step 610.

[0119] Step 606: Determine the angular frequency difference between the grid angular frequency value and the network construction angular frequency value; perform proportional-integral calculation on the angular frequency difference to obtain active power compensation data. Proceed to step 610.

[0120] Step 608: Perform Parker transformation on the three-phase AC voltage values ​​based on the initial network phase angle to obtain the direct-axis and quadrature-axis components of the three-phase AC voltage values ​​in the rotating coordinate system; perform nonlinear filtering on the direct-axis and quadrature-axis components to obtain the filtered direct-axis and quadrature-axis components, and use the filtered direct-axis and quadrature-axis components as the amplitude synchronization result. Continue to step 616.

[0121] Step 610: Obtain the initial active power reference value, actual active power, and oscillation relationship of the virtual synchronizer; correct the initial active power reference value according to the active power compensation data to obtain the corrected active power reference value; determine the power difference between the corrected active power reference value and the actual active power; update the network angular frequency value according to the power difference and oscillation relationship to obtain the updated network angular frequency value; and use the updated network angular frequency value as the virtual synchronization result.

[0122] Step 612: Determine the target network phase angle based on the virtual synchronization results and phase compensation angle.

[0123] Step 614: If the target network phase angle meets the closing conditions, send a closing permission signal.

[0124] Step 616: Perform Parker inverse transformation on the amplitude synchronization result based on the target network phase angle to obtain the network reference voltage.

[0125] Step 618: Start the grid-connected reactive power generator according to the grid reference voltage so that the grid-connected reactive power generator is in grid-connected operation.

[0126] Steps 604, 606, and 608 can be performed simultaneously. In this embodiment, the pre-synchronization function can be automatically executed after the grid-connected reactive power generator is connected to the power grid, without the need to set a separate control mode. Pre-synchronization can be completed before the grid-connected reactive power generator starts, allowing direct startup in grid-connected mode without the need for post-start mode switching between grid connection / connection or grid-connected / off-grid operation. This solves the problem of grid-connected reactive power generators still requiring phase-locked loop control. Because the entire startup process of the grid-connected reactive power generator involves no mode switching, all changes are continuous, preventing system jumps and impacts.

[0127] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0128] Based on the same inventive concept, this application also provides a pre-synchronization control device for a grid-type reactive power generator to implement the pre-synchronization control method for the grid-type reactive power generator described above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the pre-synchronization control device for a grid-type reactive power generator provided below can be found in the limitations of the pre-synchronization control method for the grid-type reactive power generator described above, and will not be repeated here.

[0129] In one exemplary embodiment, such as Figure 7 As shown, a pre-synchronization control device for a grid-type reactive power generator is provided, comprising: a data acquisition module 702, a pre-synchronization module 704, and a start-up module 706, wherein:

[0130] The data acquisition module 702 is used to acquire the three-phase AC voltage value and grid angular frequency value of the grid, as well as the initial grid-connected phase angle and grid-connected angular frequency value of the grid-connected reactive power generator after the grid-connected reactive power generator is connected to the grid.

[0131] The pre-synchronization module 704 is used to perform pre-synchronization processing on the grid-type reactive power generator based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle, and the grid angular frequency value, so as to obtain the grid reference voltage.

[0132] The starting module 706 is used to start the grid-type reactive power generator according to the grid reference voltage so that the grid-type reactive power generator is in grid-connected operation.

[0133] In an exemplary embodiment, the pre-synchronization module 704 is further configured to: perform phase synchronization on the grid-type reactive power generator based on the three-phase AC voltage value and the initial grid phase angle to obtain the phase compensation angle; perform frequency synchronization on the grid-type reactive power generator based on the grid angular frequency value and the grid angular frequency value to obtain active power compensation data; perform amplitude synchronization on the grid-type reactive power generator based on the three-phase AC voltage value and the initial grid phase angle to obtain the amplitude synchronization result; and obtain the grid reference voltage based on the phase compensation angle, the active power compensation data, and the amplitude synchronization result.

[0134] In an exemplary embodiment, the pre-synchronization module 704 is further configured to perform virtual synchronization on the grid-type reactive power generator based on active power compensation data to obtain a virtual synchronization result; determine the target grid-type phase angle based on the virtual synchronization result and the phase compensation angle; and perform Park inverse transformation on the amplitude synchronization result based on the target grid-type phase angle to obtain the grid-type reference voltage.

[0135] In an exemplary embodiment, the pre-synchronization module 704 is further configured to acquire the initial active power reference value, actual active power, and oscillation relationship of the virtual synchronizer; correct the initial active power reference value according to the active power compensation data to obtain the corrected active power reference value; determine the power difference between the corrected active power reference value and the actual active power; update the network angular frequency value according to the power difference and the oscillation relationship to obtain the updated network angular frequency value; and use the updated network angular frequency value as the virtual synchronization result.

[0136] In an exemplary embodiment, the pre-synchronization module 704 is further configured to send a closing permission signal when the target network phase angle meets the closing conditions.

[0137] In an exemplary embodiment, the pre-synchronization module 704 is further configured to perform Parker transformation on the three-phase AC voltage value according to the initial grid phase angle to obtain the direct-axis component and quadrature-axis component of the three-phase AC voltage value in the rotating coordinate system; determine the angle between the direct-axis component and the quadrature-axis component; determine the angle difference between the angle and the preset angle; and perform proportional integration on the angle difference to obtain the phase compensation angle.

[0138] In an exemplary embodiment, the pre-synchronization module 704 is further configured to add a positive or negative sign identifier to the direct axis component to obtain the direct axis component after adding the identifier; and determine the angle between the direct axis component after adding the identifier and the quadrature axis component.

[0139] In an exemplary embodiment, the pre-synchronization module 704 is further configured to determine the angular frequency difference between the grid angular frequency value and the network construction angular frequency value; and to perform proportional-integral calculation on the angular frequency difference to obtain active power compensation data.

[0140] In an exemplary embodiment, the pre-synchronization module 704 is further configured to perform Parker transformation on the three-phase AC voltage values ​​according to the initial network phase angle to obtain the direct-axis component and quadrature-axis component of the three-phase AC voltage values ​​in the rotating coordinate system; perform nonlinear filtering on the direct-axis component and quadrature-axis component to obtain the filtered direct-axis component and filtered quadrature-axis component; and use the filtered direct-axis component and filtered quadrature-axis component as the amplitude synchronization result.

[0141] Each module in the aforementioned pre-synchronization control device for a grid-type reactive power generator can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module.

[0142] In one exemplary embodiment, a computer device is provided, the internal structure of which can be as shown in the figure. Figure 8As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operating system and computer programs stored in the non-volatile storage media. The database stores data such as three-phase AC voltage values, grid angular frequency values, initial grid phase angle, grid angular frequency values, and grid reference voltage. The I / O interfaces are used for information exchange between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When executed by the processor, the computer program implements a pre-synchronization control method for a grid-type reactive power generator.

[0143] Those skilled in the art will understand that Figure 8 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0144] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0145] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0146] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0147] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0148] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0149] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0150] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A pre-synchronization control method for a grid-type reactive power generator, characterized in that, The method includes: After the grid-type reactive power generator is connected to the power grid, the three-phase AC voltage value and the grid angular frequency value of the power grid are obtained, as well as the initial grid-type reactive power generator's grid-type phase angle and grid-type angular frequency value. Based on the three-phase AC voltage value, the grid angular frequency value, the initial grid phase angle, and the grid angular frequency value, the grid-type reactive power generator is pre-synchronized to obtain the grid reference voltage. The grid-type reactive power generator is started according to the grid reference voltage so that the grid-type reactive power generator is in grid-connected operation.

2. The method according to claim 1, characterized in that, The pre-synchronization processing of the grid-type reactive power generator based on the three-phase AC voltage value, the grid angular frequency value, the initial grid-forming phase angle, and the grid-forming angular frequency value to obtain the grid-forming reference voltage includes: Based on the three-phase AC voltage values ​​and the initial grid-type phase angle, the grid-type reactive power generator is phase-synchronized to obtain the phase compensation angle. Based on the grid angular frequency value and the network angular frequency value, the network-type reactive power generator is frequency synchronized to obtain active power compensation data. Based on the three-phase AC voltage values ​​and the initial grid phase angle, the grid-type reactive power generator is subjected to amplitude synchronization to obtain the amplitude synchronization result; The grid reference voltage is obtained based on the phase compensation angle, the active power compensation data, and the amplitude synchronization result.

3. The method according to claim 2, characterized in that, The step of obtaining the grid reference voltage based on the phase compensation angle, the active power compensation data, and the amplitude synchronization result includes: The network-type reactive power generator is virtually synchronized based on the active power compensation data to obtain the virtual synchronization result; Based on the virtual synchronization result and the phase compensation angle, determine the target network phase angle; The amplitude synchronization result is subjected to Park inverse transformation based on the target network phase angle to obtain the network reference voltage.

4. The method according to claim 3, characterized in that, The virtual synchronization of the grid-type reactive power generator based on the active power compensation data, to obtain the virtual synchronization result, includes: Obtain the initial active power reference value, actual active power, and oscillation relationship of the virtual synchronous machine; The initial active power reference value is corrected based on the active power compensation data to obtain the corrected active power reference value. The power difference between the corrected active power reference value and the actual active power is determined. The network angular frequency value is updated based on the power difference and the swing relationship to obtain the updated network angular frequency value. The updated network angular frequency value is used as the virtual synchronization result.

5. The method according to claim 3, characterized in that, Before performing an inverse Parker transform on the amplitude synchronization result based on the target network phase angle to obtain the network reference voltage, the method includes: If the phase angle of the target network meets the closing conditions, a closing permission signal is sent.

6. The method according to claim 2, characterized in that, The phase compensation angle is obtained by performing phase synchronization on the grid-type reactive power generator based on the three-phase AC voltage value and the initial grid-type phase angle, including: Based on the initial network phase angle, Parker transformation is performed on the three-phase AC voltage values ​​to obtain the direct-axis and quadrature-axis components of the three-phase AC voltage values ​​in the rotating coordinate system. Determine the angle between the direct axis component and the quadrature axis component; The angle difference between the included angle and the preset angle is determined, and the phase compensation angle is obtained by performing a proportional integral operation on the angle difference.

7. The method according to claim 6, characterized in that, Determining the angle between the direct axis component and the quadrature axis component includes: Add positive and negative signs to the direct axis components to obtain the labeled direct axis components; Determine the angle between the straight axis component and the quadrature axis component after the addition of the identifier.

8. The method according to claim 2, characterized in that, The step of frequency synchronization of the grid-type reactive power generator based on the grid angular frequency value and the grid-structure angular frequency value to obtain active power compensation data includes: Determine the angular frequency difference between the power grid angular frequency value and the network construction angular frequency value; The active power compensation data is obtained by performing proportional-integral calculation on the angular frequency difference.

9. The method according to claim 2, characterized in that, The step of performing amplitude synchronization on the grid-type reactive power generator based on the three-phase AC voltage values ​​and the initial grid phase angle to obtain the amplitude synchronization result includes: Based on the initial network phase angle, Parker transformation is performed on the three-phase AC voltage values ​​to obtain the direct-axis and quadrature-axis components of the three-phase AC voltage values ​​in the rotating coordinate system. The direct-axis component and the quadrature-axis component are subjected to nonlinear filtering to obtain the filtered direct-axis component and the filtered quadrature-axis component. The filtered direct-axis component and the filtered quadrature-axis component are used as the amplitude synchronization result.

10. A pre-synchronization control device for a grid-type reactive power generator, characterized in that, The device includes: The data acquisition module is used to acquire the three-phase AC voltage value and grid angular frequency value of the grid, as well as the initial grid-connected phase angle and grid angular frequency value of the grid-connected reactive power generator after the grid-connected reactive power generator is connected to the grid. The pre-synchronization module is used to perform pre-synchronization processing on the grid-type reactive power generator based on the three-phase AC voltage value, the grid angular frequency value, the initial grid-building phase angle, and the grid-building angular frequency value to obtain the grid-building reference voltage. The startup module is used to start the grid-type reactive power generator according to the grid reference voltage, so that the grid-type reactive power generator is in grid-connected operation.

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