High-precision fast synchronization control method and device based on multi-stage variable-speed tracking

Abstract

The application discloses a high-precision fast synchronization control method and device based on multi-stage variable-speed tracking, which divides the pre-synchronization process of a system to be synchronized and an external power grid into multiple collaborative control stages which are executed in sequence; a full-speed tracking stage, in which the time required for the system to be connected to the grid to converge to synchronization through acceleration and deceleration is calculated and compared, and the direction of the frequency offset with the optimal time is determined; when the phase difference is less than a first threshold value, a prediction proportional convergence stage is entered, in which a frequency offset proportional to the phase difference is used for smooth adjustment; whether the second threshold value is reached is judged according to the phase state prediction, and a multi-variable synchronization checking stage is entered; only when the voltage difference, the frequency difference and the phase difference simultaneously satisfy the respective tolerance thresholds and remain stable, a closing command is issued. The application adopts the optimal control strategy in stages, effectively shortens the grid connection time, simultaneously suppresses overshoot and oscillation, and significantly improves the rapidity, accuracy and system reliability of the grid connection process.

Description

Technical Field

[0001] This invention relates to the field of new energy grid connection control, and in particular to a high-precision and fast synchronization control method and device based on multi-stage variable speed tracking. Background Technology

[0002] Distributed energy sources, such as photovoltaics and wind power, are rapidly increasing their penetration rate in power systems. Inverters are used to achieve rapid and precise synchronization between the system to be connected to the grid and the main grid. At the moment of grid connection, the voltage, frequency, and phase of the system to be connected should be consistent with the main grid. Insufficient precision at the moment of connection may trigger inrush currents, which can damage inverter equipment and even affect the stable operation of the grid. Therefore, a fast and high-precision grid connection control strategy needs to be developed.

[0003] In existing grid-connected control technologies, synchronization strategies based on proportional-integral (PI) controllers are widely used. This method detects the phase difference between the system to be connected to the grid and the main grid, uses the PI controller to generate frequency compensation commands, and dynamically adjusts the frequency of the system to be connected to the grid to ultimately achieve phase synchronization. However, in pursuit of rapid synchronization, traditional PI control methods often require setting large controller gain parameters. When the initial phase difference is large, a very large initial frequency adjustment will be generated, causing severe overshoot and oscillations in the frequency of the system to be connected to the grid during the adjustment process. This not only prolongs the settling time of the entire system, but also causes unnecessary disturbances to the stability of the loads or microgrids connected within the system before grid connection, which runs counter to the goal of high-precision, smooth grid connection.

[0004] To overcome the problem of large frequency fluctuations caused by PI control, a fixed-frequency tracking synchronization method has been developed. This method sets a fixed, small frequency difference (e.g., 0.2Hz), allowing the system to be connected to the grid to slowly catch up with the main grid phase at a constant rate. While this method effectively avoids drastic frequency fluctuations during synchronization and ensures the smoothness of the adjustment process, its cost is a very slow synchronization speed. Especially when the initial phase difference is close to 360 degrees, the entire synchronization process may take several seconds or even longer, which cannot meet the needs of some application scenarios requiring rapid response and grid connection. More importantly, even when the phase difference is about to approach zero, the system still maintains this fixed frequency difference, resulting in a still large frequency difference at the critical stage before closing, making it difficult to meet the grid connection conditions.

[0005] In summary, existing grid-connected control technologies struggle to simultaneously achieve both synchronization speed and smooth regulation. Traditional PI control sacrifices frequency stability for speed, while fixed-frequency tracking methods sacrifice valuable time for stability. Therefore, there is an urgent need to develop a novel grid-connected control method that can rapidly eliminate phase differences in the initial stage while ensuring stability and accuracy of frequency and voltage during synchronization and closing, thereby achieving optimal time and high-precision control throughout the entire grid-connection process. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes a high-precision, fast synchronization control method based on multi-stage variable speed tracking, belonging to the field of new energy grid connection control. It organically combines time-optimal decision-making with predictive control, effectively shortening the grid connection time while suppressing overshoot and oscillation, significantly improving the speed, accuracy, and system reliability of the grid connection process.

[0007] One of the objectives of this invention is achieved through the following technical solution: Firstly, this invention provides a high-precision, fast synchronization control method based on multi-stage variable speed tracking, wherein the method sequentially executes the following cooperative control stages:

[0008] Step 1: Data Measurement Phase: Acquire the frequency, phase, and voltage of the external power grid and the system to be synchronized, and calculate the frequency difference between them. Phase difference and voltage difference ;

[0009] Step 2: Full-speed tracking phase: After receiving the synchronous start signal, the direction of the maximum frequency offset is selected by the time-optimal decision algorithm, thereby obtaining the frequency adjustment amount and the fast tracking frequency, and reducing the phase difference with the fastest path. When the phase difference is less than the first phase threshold, the prediction proportional convergence phase is entered.

[0010] Step 3: Predictive proportional convergence stage: Frequency regulation is changed to obtain frequency regulation amount using a proportional controller, voltage regulation is calculated to obtain voltage compensation command using a PI controller, and phase trajectory prediction is executed in parallel. When the phase state reaches the second phase threshold, it enters the multivariate synchronous verification stage.

[0011] Step 4: Multi-variable synchronization verification stage: While continuing the frequency and voltage adjustments in Step 3, execute the frequency difference... Phase difference Voltage difference Three-variable synchronous verification;

[0012] Step 5: Closing Phase: After the synchronization verification is passed, the closing signal is output and the three-variable adjustment command is frozen.

[0013] Furthermore, the fast tracking frequency in step 2 is obtained through a time-optimal decision algorithm, specifically including the following steps:

[0014] Step 2.1: Calculate the maximum angular frequency offset;

[0015] Step 2.2: When the external power grid is ahead of the system to be connected to, calculate the time required for the system to be connected to accelerate and catch up with the external power grid, and the time required for the system to decelerate and for the external power grid to catch up with the system to be connected to.

[0016] Step 2.3: When the external power grid lags behind the system to be connected to, calculate the time required for the system to be connected to accelerate and catch up with the external power grid, and the time required for the system to decelerate and for the external power grid to catch up with the system to be connected to decelerate.

[0017] Step 2.4: Determine the direction of the maximum frequency offset based on the time required for the system to be connected to the grid to accelerate and decelerate in order to catch up;

[0018] Step 2.5: Based on the maximum offset direction obtained in Step 2.4, the frequency adjustment amount is obtained and superimposed on the Pf control loop in the droop control. Based on the frequency rating in the droop control, the frequency is quickly tracked.

[0019] Furthermore, the specific steps for phase trajectory prediction in step 3 are as follows:

[0020] Step 3.1: Set the prediction feedforward time based on the feedforward period and control period;

[0021] Step 3.2: Calculate the predicted phase difference based on the sampled phase difference and the predicted phase difference.

[0022] Furthermore, voltage regulation is achieved through a discrete PI controller during the prediction proportional convergence phase and the multivariate synchronous verification phase.

[0023] Furthermore, the three-variable synchronization verification in step 4 is as follows:

[0024] The absolute value of the phase difference must be satisfied simultaneously for three consecutive control cycles. absolute value of voltage difference absolute value of frequency difference .

[0025] Furthermore, step 5 specifically includes the following process:

[0026] Step 5.1: Output closing signal;

[0027] Step 5.2: Set both frequency adjustment and voltage adjustment to 0.

[0028] Furthermore, the frequency regulation and voltage regulation are superimposed on the reference values ​​of the PF and QV loops in the network control, respectively, thereby achieving active synchronous regulation of voltage and frequency while retaining the characteristics of network control.

[0029] Secondly, the present invention also provides a high-precision fast synchronization control device based on multi-stage variable speed tracking, including a memory and one or more processors. The memory stores executable code, and when the processor executes the executable code, it implements the multi-stage time-optimal high-precision grid-connected control method.

[0030] Thirdly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the aforementioned multi-stage time-optimal high-precision grid-connected control method.

[0031] Fourthly, the present invention also provides a computer program product, including a computer program, which, when executed by a processor, implements the multi-stage time-optimal high-precision grid-connected control method.

[0032] The beneficial effects of this invention are:

[0033] (1) The present invention adopts a multi-stage collaborative control strategy. In the initial stage, the time-optimal algorithm is used to achieve rapid tracking of phase difference, which greatly shortens the synchronization time and solves the problem of excessive time consumption of the fixed frequency tracking method. When approaching the synchronization point, it switches to the high-precision fine-tuning mode to ensure the stability of the adjustment process and the high precision of the closing point, avoiding the frequency oscillation caused by the traditional PI control in pursuit of speed.

[0034] (2) This invention uses a time-optimal decision algorithm to accurately calculate and select the shortest path for acceleration or deceleration to eliminate phase difference, and tracks with the maximum allowable frequency offset. Compared with the "uniform speed" convergence of the fixed-frequency tracking method, the "full speed" tracking mode of this invention can complete the main stage of the synchronization process at the fastest speed, thus improving grid connection efficiency.

[0035] (3) This invention decomposes the complex grid connection process into multiple stages with clear objectives. The switching of each stage is triggered by clear physical quantities, thereby realizing the automation of the control process. This method is not sensitive to the magnitude of the initial phase difference. Regardless of the initial state, it can automatically find the optimal synchronization path. The synchronization speed is fast and robust, and it is easy to implement in engineering.

[0036] (4) The present invention can actively predict the arrival time of the synchronization point through the phase trajectory prediction algorithm and switch to the final synchronization verification stage in advance, realizing intelligent feedforward control. In contrast, the traditional zero-crossing detection method passively "wait" for the zero point to appear before making corrections, which lacks foresight. Attached Figure Description

[0037] Figure 1 This is a flowchart of a high-precision, fast synchronization control method based on multi-stage variable speed tracking, as described in Embodiment 1.

[0038] Figure 2 This is a schematic diagram of the voltage phasors of the external power grid leading the system to be connected to the grid in Example 1;

[0039] Figure 3 This is a schematic diagram of the voltage phasors of the external power grid lagging behind the system to be connected to the grid in Example 1;

[0040] Figure 4 This is a droop control block diagram of Embodiment 1;

[0041] Figure 5 This is the grid connection test system topology of the photovoltaic-storage microgrid and the external power grid in Example 2;

[0042] Figure 6 This is the energy storage output voltage waveform of Example 2;

[0043] Figure 7 This is the energy storage output current waveform of Example 2;

[0044] Figure 8 These are the active and reactive power waveforms of the energy storage output in Example 2;

[0045] Figure 9 This is the frequency adjustment amount in Example 2. Voltage regulation ;

[0046] Figure 10 The circuit breaker closing signal and frequency difference in Example 2 Phase difference Voltage difference Condition;

[0047] Figure 11 This describes the frequency changes of the system to be connected to the grid and the external power grid in Example 2.

[0048] Figure 12 This is a structural diagram of a high-precision, fast synchronization control device based on multi-stage variable speed tracking according to the present invention. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0050] Example 1:

[0051] like Figure 1 As shown, a high-precision, fast synchronization control method based on multi-stage variable speed tracking includes the following steps:

[0052] Step 1: Data Measurement Phase: Obtain the frequency, phase, and voltage of the external power grid and the frequency, phase, and voltage of the system to be synchronized, and calculate the frequency difference. Phase difference Voltage difference .

[0053] Step 2: Full-speed tracking phase: After receiving the synchronous start signal, the maximum frequency offset is selected using a time-optimal decision algorithm. direction Thus, the frequency adjustment amount is obtained. With fast tracking frequency This reduces the phase difference using the fastest path. Specifically, it includes the following steps:

[0054] Step 2.1: Calculate the maximum angular frequency offset ;

[0055] Step 2.2: When the external power grid leads the system to be connected to the grid, i.e. ,like Figure 2 As shown. Acceleration of the grid-connected system (i.e. The time required to catch up with the external power grid is: The grid-connected system is slowing down (i.e.) The time required for the external power grid to catch up with the system to be connected to the grid is: ;

[0056] Step 2.3: When the external power grid lags behind the system to be connected to the grid, i.e. ,like Figure 3 As shown. Acceleration of the grid-connected system (i.e. The time required to catch up with the external power grid is: The grid-connected system is slowing down (i.e.) The time required for the external power grid to catch up with the system to be connected to the grid is: ;

[0057] Step 2.4: Compare the time required for the grid-connected system to accelerate and catch up with the time required to decelerate. This indicates that the time for the grid-connected system to decelerate and catch up is shorter, and the direction of the maximum frequency offset should be selected. -1; when This indicates that the time for the grid-connected system to catch up is shorter, and the direction of the maximum frequency offset should be selected. =1;

[0058] Step 2.5: Based on the maximum offset direction obtained in Step 2.4 The frequency adjustment amount is obtained. Superimposed on the Pf control loop of the original droop control, the fast tracking frequency is obtained. ,in This is the frequency value in the original droop control.

[0059] Step 3: Predicted Proportional Convergence Phase: When the first switching condition is met, switch to this step; frequency regulation is changed to obtain the frequency regulation amount using a proportional controller. Voltage regulation uses a PI controller to calculate the voltage compensation command. And in parallel, phase trajectory prediction is performed to determine the timing of the next switching step. Specifically, this includes the following steps:

[0060] Step 3.1: Set the prediction feedforward time ,in To predict the number of feedforward cycles, To control the cycle, the value is set. .

[0061] Step 3.2: Calculate the predicted phase difference using the following formula. :

[0062]

[0063] in, Let be the predicted phase difference at time t. The phase difference is measured at time t.

[0064] Furthermore, voltage regulation is activated only in steps 3 and 4, and is implemented via a discrete PI controller:

[0065]

[0066] in, This is the control output at the k-th sampling time. The voltage difference measured at the k-th sampling time. These are the proportional-integral coefficients, where they are 0.5 and 30 respectively.

[0067] Step 4: Multi-variable synchronization verification stage: When the second switching condition is met, switch to this step; while continuously adjusting the frequency and voltage, perform frequency difference... Phase difference Voltage difference Three-variable synchronization verification: simultaneously satisfying the following conditions within three consecutive control cycles: absolute value of phase difference absolute value of voltage difference absolute value of frequency difference .

[0068] Step 5: Closing Phase: After the synchronization verification passes, a closing signal is output and the three-variable regulation command is frozen. This includes the following steps:

[0069] Step 5.1: Output closing signal ;

[0070] Step 5.2: Set the frequency adjustment amount Voltage regulation .

[0071] Furthermore, the first switching condition for proceeding to step 3 is: ,in The first phase threshold has a value of The second switching condition for proceeding to step 4 is: ,in The second phase threshold has a value of ;

[0072] The multi-stage time-optimal high-precision grid-connected control method proposed in this invention uses the measured voltage, frequency, and phase on both sides of the grid connection point as input quantities, and the voltage regulation quantity, frequency regulation quantity, and closing signal as output quantities, wherein the frequency regulation quantity... Voltage regulation These values ​​are all superimposed on the PF and QV loop reference values ​​in the network control. Taking droop control as an example, a network control can be constructed as follows: Figure 4 The control block diagram shown here contains a loop body composed of droop characteristic equations:

[0073]

[0074] In the formula, , These are the frequency and voltage reference values ​​in network-type control. , Reference values ​​for active and reactive power in grid-type control; , This refers to the actual output active power and reactive power. , The droop characteristic equation contains the active power-frequency coefficient and the reactive power-voltage coefficient. , The output frequency and voltage values ​​are obtained after applying the droop characteristic equation.

[0075] The frequency and voltage adjustment values ​​are added to the frequency and voltage value generation stages, which can be specifically expressed as follows:

[0076]

[0077] In the formula, , These are frequency adjustment and voltage adjustment values; , The adjusted output frequency and voltage values.

[0078] Example 2:

[0079] The embodiments are experimental simulations performed according to the method described in Embodiment 1.

[0080] In this embodiment, to fully demonstrate the practical effect of the multi-stage time-optimal high-precision grid-connected control method, a system was built using MATLAB / Simulink as follows: Figure 5 The grid-connected test model of the photovoltaic-storage microgrid and the external power grid shown in this invention consists of a microgrid system to be connected to the grid, comprising energy storage units using grid-based control, a photovoltaic array using grid-following control, and AC loads, as well as a circuit breaker and an external power grid simulated by a three-phase programmable power supply. The synchronous grid-connected controller proposed in this invention is connected in parallel with the circuit breaker and is responsible for collecting information from the system to be connected to the grid and the external power grid, and sending control signals to the grid-based energy storage inverter for control. Furthermore, the rated frequency of the external power grid is 50Hz, and the voltage level is 380V. The energy storage system employs droop control, with a rated power of 140kW, a rated frequency of 50Hz, a frequency regulation coefficient of 150kW / Hz, and a voltage regulation coefficient of 10kVar / V. The photovoltaic system uses PQ control, with a rated active power of 10kW and a rated reactive power of 0kVar. The AC load is 140kW. The external grid line resistance is 0.1Ω, and the line inductance is 3mH. The line resistance of the system to be connected to the grid is 0.1Ω, and the line inductance is 0.2mH. The circuit breaker closing delay is 10ms. A synchronization signal is set to be sent at 1s.

[0081] Figure 6 The output voltage waveform for energy storage. Figure 7 The output current waveform for energy storage; Figure 8 The waveforms of active and reactive power output from the energy storage system; Figure 9 Frequency adjustment amount Voltage regulation ; Figure 10 Circuit breaker closing signal, frequency difference Phase difference Voltage difference Condition; Figure 11The waveform diagram shows the frequency changes of the system to be connected to the grid and the external power grid. As can be seen from the waveform, after receiving the synchronization start signal at 1 second, the multi-stage time-optimal high-precision grid-connected control proposed in this invention starts, with an initial phase difference of -71°. First, it enters the full-speed tracking stage, where the system frequency deviation is adjusted to 1Hz, lasting 192ms, and the phase difference decreases to 3°. Then, it enters the predictive proportional convergence stage, where the frequency deviation changes with the phase difference, gradually decreasing to 1°. Next, it enters the multi-variable synchronization verification stage. When the synchronization verification conditions are met, a closing signal is output, and the three-variable adjustment commands are frozen. After 243ms, the circuit breaker closes at 1.243s (including a 10ms closing action delay). At the moment of closing, the phase difference is 0.16°, the voltage difference is 4.3V, and the frequency difference is 0.06Hz. All three variables are basically consistent with the external power grid at the moment of closing, resulting in minimal impact after closing and achieving time-optimal high-precision grid-connected control.

[0082] In contrast, if the traditional fixed-frequency tracking method is used, the frequency deviation is usually set to a small value (e.g., ...) to avoid impact during closing. (0.1Hz). Because this method lacks time-optimal path decision-making capability, calculations show that eliminating a -71° phase difference requires a minimum of 1.971s and a maximum of 8.028s, significantly longer than the strategy proposed in this invention. Furthermore, if a traditional PI control method is used, a large initial frequency adjustment will be generated when the initial phase difference is large, leading to severe overshoot and oscillations in the frequency of the system to be connected to the grid during the adjustment process, making it difficult to achieve stable and accurate grid connection in a short time. In contrast, this invention can achieve high-precision and rapid grid connection.

[0083] Example 3:

[0084] Corresponding to the aforementioned embodiment of a high-precision fast synchronization control method based on multi-stage variable speed tracking, the present invention also provides an embodiment of a high-precision fast synchronization control device based on multi-stage variable speed tracking.

[0085] See Figure 12 The present invention provides a high-precision fast synchronization control device based on multi-stage variable speed tracking, comprising a memory and one or more processors. The memory stores executable code, and when the processor executes the executable code, it is used to implement a high-precision fast synchronization control method based on multi-stage variable speed tracking in the above embodiment.

[0086] The embodiment of the high-precision, fast synchronization control device based on multi-stage variable speed tracking provided by this invention can be applied to any device with data processing capabilities, such as a computer. The device embodiment can be implemented through software, hardware, or a combination of both. Taking software implementation as an example, as a logical device, it is formed by the processor of any data processing device loading the corresponding computer program instructions from non-volatile memory into memory for execution. From a hardware perspective, such as... Figure 12 The diagram shown is a hardware structure diagram of any device with data processing capabilities, which is a high-precision, fast synchronization control device based on multi-stage variable speed tracking provided by the present invention. (Except for...) Figure 12 In addition to the processor, memory, network interface, and non-volatile memory shown, any data processing device in the embodiment may also include other hardware depending on the actual function of the data processing device, which will not be described in detail here.

[0087] The specific implementation process of the functions and roles of each unit in the above device can be found in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0088] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and 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 modules can be selected to achieve the purpose of the present invention according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0089] This invention also provides a computer-readable storage medium storing a program thereon, which, when executed by a processor, implements a high-precision, fast synchronization control method based on multi-stage variable speed tracking as described in the above embodiments.

[0090] The computer-readable storage medium can be an internal storage unit of any data processing device described in any of the foregoing embodiments, such as a hard disk or memory. The computer-readable storage medium can also be an external storage device of any data processing device, such as a plug-in hard disk, smart media card (SMC), SD card, flash card, etc., equipped on the device. Furthermore, the computer-readable storage medium can include both internal storage units and external storage devices of any data processing device. The computer-readable storage medium is used to store the computer program and other programs and data required by the data processing device, and can also be used to temporarily store data that has been output or will be output.

[0091] The present invention also provides a computer program product, including a computer program, which, when executed by a processor, implements the aforementioned high-precision fast synchronization control method based on multi-stage variable speed tracking.

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-precision, fast synchronization control method based on multi-stage variable speed tracking, characterized in that, The method executes the following collaborative control phases sequentially: Step 1: Data Measurement Phase: Acquire the frequency, phase, and voltage of the external power grid and the system to be synchronized, and calculate the frequency difference between them. Phase difference and voltage difference ; Step 2: Full-speed tracking phase: After receiving the synchronization start signal, the direction of the maximum frequency offset is selected through the time-optimal decision algorithm, thereby obtaining the frequency adjustment amount and the fast tracking frequency. The phase difference is reduced using the fastest path. When the phase difference is less than the first phase threshold, the prediction proportional convergence phase begins. The specific process of obtaining the fast tracking frequency includes the following steps: Step 2.1: Calculate the maximum angular frequency offset; Step 2.2: When the external power grid is ahead of the system to be connected to, calculate the time required for the system to be connected to accelerate and catch up with the external power grid, and the time required for the system to decelerate and for the external power grid to catch up with the system to be connected to. Step 2.3: When the external power grid lags behind the system to be connected to the grid, calculate the time required for the system to be connected to the grid to accelerate and catch up with the external power grid, and the time required for the system to be connected to the grid to decelerate so that the external power grid catches up with the system to be connected to the grid. Step 2.4: Determine the direction of the maximum frequency offset based on the time required for the system to be connected to the grid to accelerate and decelerate in order to catch up; Step 2.5: Based on the maximum offset direction obtained in Step 2.4, the frequency adjustment amount is obtained and superimposed on the Pf control loop in the droop control. Based on the frequency rating in the droop control, the frequency is quickly tracked. Step 3: Predictive proportional convergence stage: Frequency regulation is changed to obtain frequency regulation amount using a proportional controller, voltage regulation is calculated to obtain voltage compensation command using a PI controller, and phase trajectory prediction is executed in parallel. When the phase state reaches the second phase threshold, it enters the multivariate synchronous verification stage. Step 4: Multi-variable synchronization verification stage: While continuing the frequency and voltage adjustments in Step 3, execute the frequency difference... Phase difference Voltage difference Three-variable synchronous verification; Step 5: Closing Phase: After the synchronization verification is passed, the closing signal is output and the three-variable adjustment command is frozen.

2. The high-precision, fast synchronization control method based on multi-stage variable speed tracking according to claim 1, characterized in that, The specific steps for phase trajectory prediction in step 3 are as follows: Step 3.1: Set the prediction feedforward time based on the feedforward period and control period; Step 3.2: Calculate the predicted phase difference based on the phase difference measured at the current time and the phase difference measured in the previous cycle.

3. The high-precision, fast synchronization control method based on multi-stage variable speed tracking according to claim 1, characterized in that, Voltage regulation is achieved through a discrete PI controller during the prediction proportional convergence phase and the multivariable synchronous verification phase.

4. The high-precision, fast synchronization control method based on multi-stage variable speed tracking according to claim 1, characterized in that, The three-variable synchronization verification in step 4 is as follows: The absolute value of the phase difference must be satisfied simultaneously for three consecutive control cycles. absolute value of voltage difference absolute value of frequency difference .

5. The high-precision, fast synchronization control method based on multi-stage variable speed tracking according to claim 1, characterized in that, The specific process of step 5 includes: Step 5.1: Output closing signal; Step 5.2: Set both frequency adjustment and voltage adjustment to 0.

6. The high-precision, fast synchronization control method based on multi-stage variable speed tracking according to claim 1, characterized in that, The frequency regulation and voltage regulation are superimposed on the reference values ​​of the PF and QV loops in the network control, respectively, thereby achieving active synchronous regulation of voltage and frequency while retaining the characteristics of network control.

7. A high-precision, fast synchronization control device based on multi-stage variable speed tracking, comprising a memory and one or more processors, wherein the memory stores executable code, characterized in that... When the processor executes the executable code, it implements the high-precision fast synchronization control method based on multi-stage variable speed tracking as described in any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the high-precision fast synchronization control method based on multi-stage variable speed tracking as described in any one of claims 1 to 6.

9. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements a high-precision, fast synchronization control method based on multi-stage variable speed tracking as described in any one of claims 1 to 6.

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