Satellite time service-based micro-grid inverter synchronization method and system

Abstract

This invention relates to the field of microgrid control technology and discloses a method and system for synchronizing microgrid inverters based on satellite time synchronization. The method includes at least: receiving a satellite time synchronization signal and preprocessing it to obtain a global time reference signal; acquiring real-time operating parameters of each inverter within the microgrid and calculating the real-time phase offset of each inverter based on the global time reference signal and each real-time operating parameter; generating a synchronization phase angle for the corresponding inverter based on each real-time phase offset; acquiring real-time interaction data of each inverter and updating each initial phase adjustment command based on the real-time interaction data and the global synchronization phase angle to obtain a target phase adjustment command for the corresponding inverter; and adjusting the output voltage of the corresponding inverter using each target phase adjustment command. This invention improves the synchronization control accuracy and operational stability of multi-inverter clusters in microgrids.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-grid control, in particular to a micro-grid inverter synchronization method and system based on satellite time service. BACKGROUND

[0002] As a new type of power grid architecture integrating multiple distributed power sources, energy storage devices and loads, micro-grid is an important part of smart grid and new power system, and plays a key role in improving local consumption of distributed energy and ensuring power supply reliability. Inverter is a power electronic device connecting distributed power sources and AC bus in micro-grid, which mainly realizes the conversion of DC to high-quality AC power, and is the core unit of stable operation of micro-grid. When multiple distributed power sources are connected in parallel, precise synchronization control of the output voltage of each inverter must be implemented to ensure that the frequency, phase and amplitude are consistent, so as to avoid circulating current and power oscillation between inverters, and ensure safe and stable operation of micro-grid and high-quality power output.

[0003] At present, multi-inverter synchronization control mainly adopts three types of technical solutions, namely master-slave control, droop control and control based on local communication. Master-slave control relies on a single master inverter to provide a synchronization reference, and the remaining inverters follow passively. Although the architecture is simple, there is a risk of single-point failure of the master device, and the overall system reliability is low. Droop control is a distributed control strategy without communication, which realizes power distribution and frequency synchronization by simulating the external characteristics of synchronous generators, without the need for communication networking. However, it has inherent frequency and voltage deviation, poor power quality and slow dynamic response speed. The control scheme based on local communication achieves cooperative synchronization through information exchange between inverters, with high synchronization accuracy, but is easily limited by communication delay, bandwidth and link reliability, making it difficult to implement in large-scale micro-grids or complex operating environments. SUMMARY

[0004] In view of the above problems existing in the prior art, the present application provides a micro-grid inverter synchronization method and system based on satellite time service, which uses satellite signals as a global time reference and combines a multi-micro-grid active networking control strategy to achieve phase synchronization of multiple inverters and improve the stability of micro-grid operation.

[0005] In a first aspect, the embodiments of the present application provide a micro-grid inverter synchronization method based on satellite time service, comprising: receiving a satellite time signal and preprocessing the satellite time signal to obtain a global time reference signal; obtaining real-time operating parameters of each inverter in the micro-grid, and based on the global time reference signal and each real-time operating parameter, calculating the real-time phase offset of each inverter; Based on each of the real-time phase offsets, a corresponding synchronization phase angle for the inverter is generated, wherein the synchronization phase angles of each inverter are the same and can all be used as global synchronization phase angles; The real-time load change of each inverter is obtained, and an initial phase adjustment command corresponding to the inverter is generated based on each real-time load change and the global synchronization phase angle. The real-time interactive data of each inverter is acquired, and the initial phase adjustment command is updated based on the real-time interactive data and the global synchronization phase angle to obtain the target phase adjustment command for the corresponding inverter. The output voltage of the corresponding inverter is adjusted using each of the target phase adjustment commands.

[0006] Preferably, after receiving the satellite timing signal and preprocessing the satellite timing signal to obtain a global time reference signal, the method further includes: The satellite timing signal quality index is continuously monitored. When the satellite timing signal quality index does not meet the preset signal quality requirements, a backup time reference signal is generated through the local clock, and the backup time reference signal is used as the global time reference signal.

[0007] Preferably, after generating the corresponding synchronization phase angle of the inverter based on each of the real-time phase offsets, the method further includes: Acquire the operating status data of each inverter and monitor the status indicators of the common coupling point of the microgrid; Based on the common coupling point status index, it is determined whether the microgrid is about to enter the operation mode switching state; When it is determined that the microgrid is about to enter the operation mode switching state, the operation mode switching time of the corresponding inverter is predicted based on the global time reference signal and each operation state data. Based on the switching time of each operating mode, the synchronization phase angle of the corresponding inverter is pre-adjusted.

[0008] Preferably, the step of receiving the satellite timing signal and preprocessing the satellite timing signal to obtain a global time reference signal includes: Satellite timing signals are received by a self-synchronizing receiver deployed in a microgrid, and the satellite timing signals are preprocessed by the self-synchronizing receiver to obtain a global time reference signal. The preprocessing includes extracting time codes, transmission delay compensation, and signal shaping.

[0009] Preferably, the step of acquiring the real-time operating parameters of each inverter in the microgrid, and calculating the real-time phase offset of each inverter based on the global time reference signal and each of the real-time operating parameters, includes: Real-time operating parameters of each inverter are collected by sensors installed at the output of each inverter in the microgrid. Each of the aforementioned real-time operating parameters is extracted to obtain the corresponding real-time output phase of the inverter; Based on the global time reference signal, calculate the real-time reference phase that all the inverters should achieve; Each of the real-time output phases is differentially calculated with the real-time reference phase to obtain the real-time phase offset of the corresponding inverter.

[0010] Preferably, generating the corresponding synchronization phase angle of the inverter based on each of the real-time phase offsets includes: Each of the real-time phase offsets is filtered, and each filtered real-time phase offset is integrated to obtain the corresponding synchronous phase angle of the inverter.

[0011] Preferably, the step of acquiring the real-time load change of each inverter and generating an initial phase adjustment command corresponding to the inverter based on each real-time load change and the global synchronization phase angle includes: The real-time load change of each inverter is obtained by a sensor installed at the output of each inverter in the microgrid. Each of the real-time load changes is converted into the corresponding correction phase of the inverter through droop control. Each of the correction phases is superimposed on the global synchronization phase angle to obtain the initial phase adjustment command for the corresponding inverter.

[0012] Preferably, the step of acquiring real-time interactive data for each inverter and updating each initial phase adjustment command based on the real-time interactive data and the global synchronization phase angle to obtain the target phase adjustment command corresponding to the inverter includes: Real-time interactive data of each inverter is acquired through a sensor communication network deployed within the microgrid and covering the entire inverter cluster. Based on each of the real-time interactive data and the global synchronization phase angle, an optimization adjustment command corresponding to the inverter is generated. Each initial phase adjustment command and its corresponding optimized adjustment command are superimposed to obtain the target phase adjustment command for the inverter.

[0013] Preferably, adjusting the output voltage of the corresponding inverter using each of the target phase adjustment commands includes: Each target phase adjustment command is sent to the corresponding inverter so that each inverter adjusts the phase and frequency of its output voltage based on the corresponding target phase adjustment command.

[0014] Secondly, embodiments of the present invention provide a microgrid inverter synchronization system based on satellite time synchronization, comprising: The signal receiving and processing module is used to receive satellite timing signals and preprocess the satellite timing signals to obtain a global time reference signal; The phase offset calculation module is used to obtain the real-time operating parameters of each inverter in the microgrid, and calculate the real-time phase offset of each inverter based on the global time reference signal and each of the real-time operating parameters. The synchronization phase calculation module is used to generate the synchronization phase angle of the corresponding inverter based on each of the real-time phase offsets, wherein the synchronization phase angle of each inverter is the same and can be used as the global synchronization phase angle. An initial instruction generation module is used to obtain the real-time load change of each inverter and generate an initial phase adjustment instruction corresponding to the inverter based on each real-time load change and the global synchronization phase angle. The initial instruction update module is used to acquire real-time interactive data of each inverter and update each initial phase adjustment instruction based on the real-time interactive data and the global synchronization phase angle to obtain the target phase adjustment instruction corresponding to the inverter. The inverter cluster execution module is used to adjust the output voltage of the corresponding inverter using each of the target phase adjustment commands.

[0015] Compared with existing technologies, the microgrid inverter synchronization method and system based on satellite timing in this invention have the following advantages: A high-precision global time reference is generated through preprocessing of satellite timing signals, eliminating phase accumulation errors caused by local clock drift at the source and ensuring complete uniformity of the synchronization phase angle of each inverter; the phase offset is calculated by combining real-time inverter operating parameters to generate a global synchronization phase angle, achieving precise phase and frequency synchronization of the output voltage of multiple inverters; an initial phase adjustment command is generated based on real-time load changes, enabling rapid response to load fluctuations and balanced power distribution; the target phase adjustment command is optimized and updated using real-time interactive data between inverters, effectively suppressing reactive power circulation between units and achieving cluster collaborative correction without relying on master-slave control and complex communication networks, significantly improving the reliability, power quality, and environmental adaptability of microgrid parallel operation. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating a microgrid inverter synchronization method based on satellite time synchronization according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the process for obtaining the real-time phase offset of each inverter according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the process for generating the initial phase adjustment command for each inverter according to an embodiment of the present invention; Figure 4 This is a flowchart illustrating the process of obtaining the target phase adjustment command for each inverter according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of a microgrid inverter synchronization system based on satellite time synchronization according to an embodiment of the present invention; Figure label: 01. Signal Reception and Processing Module; 02. Phase Offset Calculation Module; 03. Synchronization Phase Calculation Module; 04. Initial Command Generation Module; 05. Initial Command Update Module; 06. Inverter Cluster Execution Module. Detailed Implementation

[0017] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0018] In the description of this invention, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] like Figure 1 The diagram shown is a flowchart illustrating a microgrid inverter synchronization method based on satellite timing according to an embodiment of the present invention. (Refer to...) Figure 1 This invention discloses a microgrid inverter synchronization method based on satellite timing, comprising the following steps: S1. Receive satellite timing signals and preprocess the satellite timing signals to obtain a global time reference signal; Satellite timing signals are received by a self-synchronizing receiver deployed in the microgrid, and the global time reference signal is obtained by preprocessing the satellite timing signals using the self-synchronizing receiver. The preprocessing includes extracting time codes, compensating for transmission delays, and shaping the signal.

[0020] Specifically, the self-synchronizing receiver deployed in the microgrid receives satellite timing signals via an antenna. Its internal demodulation module processes the data to extract the raw data stream containing satellite time, ephemeris, and location information. The processor of the self-synchronizing receiver then performs protocol parsing on the raw data stream, identifying and extracting the time encoding information broadcast by the satellite's atomic clock. The processor then calculates the signal transmission distance by combining the location information with locally stored geographic location information, performs transmission delay compensation calculations based on the speed of light, and generates a compensated time signal to eliminate transmission errors. The calculation formula for the compensated time signal is as follows: in, This represents the compensation time signal obtained after delay compensation. This refers to the time-coded information directly parsed from the satellite time signal. The calculated straight-line distance between the satellite and the self-synchronizing receiver can be obtained by analyzing satellite ephemeris data and combining it with the local coordinates of the self-synchronizing receiver. The speed of light is a physical constant.

[0021] It should be noted that although this compensation time signal is numerically very precise, it is still a digital quantity within the processor. Signal shaping processing is required to make it usable as a stable and reliable physical signal source.

[0022] Furthermore, by using a dedicated circuit module to shape the compensation time signal, the digital time signal is converted into a standard physical clock signal with steep pulses and precise timing. This provides a global time reference signal with no physical delay error for all inverters in the microgrid.

[0023] In one embodiment, at a certain moment, the self-synchronizing receiver in the microgrid receives a BeiDou satellite signal, and its internal processor successfully demodulates and extracts the raw data stream. Through parsing, the processor obtains time-coded information, displaying the current time as 10:25:30.08. Simultaneously, based on the satellite ephemeris data in the signal and its own positioning, the processor calculates that the straight-line distance between the satellite and the ground receiver at this moment is 24,000 kilometers.

[0024] The transmission delay compensation calculation was then initiated. The delay time was 24,000 kilometers divided by the speed of light, which is approximately 0.08 seconds. The processor subtracted this 0.08-second transmission delay from the received timestamp of 10:25:30.08 seconds to obtain a compensated time signal, which represents the precise ground time of 10:25:30.00 seconds.

[0025] Finally, this digital time information, accurate to the second, is sent to the signal shaping unit. This unit outputs a high-level second pulse at exactly 10:25:30.00. This stable and precise physical pulse signal is the global time reference signal, which can be directly acquired and used as the absolute time starting point for synchronization calculations.

[0026] To ensure the continuous and stable output of the global time reference signal, a signal quality anomaly response mechanism needs to be established in the satellite timing signal quality monitoring and global time reference protection phases.

[0027] Specifically, after step S1, the following steps are also included: The satellite timing signal quality index is continuously monitored. When the satellite timing signal quality index does not meet the preset signal quality requirements, a backup time reference signal is generated through the local clock and used as the global time reference signal.

[0028] Specifically, satellite timing signal quality indicators are monitored through a self-synchronizing receiver. These indicators include, but are not limited to, the signal-to-noise ratio (SNR), the number of visible satellites, and the accuracy of satellite geometric distribution. Preset signal quality requirements are set, such as requiring the SNR to be higher than a certain threshold, or requiring at least four satellites to be locked simultaneously to ensure positioning and timing accuracy.

[0029] During normal operation, the self-synchronizing receiver continuously compares the real-time monitored signal quality indicators with these preset signal quality requirements. If any indicator fails to meet the requirements, such as due to building obstruction or strong electromagnetic interference causing a temporary interruption of the satellite signal, the primary time source is immediately determined to have failed. At this point, a backup time reference signal is automatically generated. This backup time reference signal is not generated out of thin air, but originates from a highly stable local clock source integrated within the self-synchronizing receiver, typically a temperature-compensated or temperature-controlled crystal oscillator. When the satellite signal is good, the frequency and phase of this local clock source are calibrated and tamed by the satellite's atomic clock signal over a long period, resulting in virtually no error. When the satellite signal is lost, it continues to output a high-precision time signal for a certain period thanks to its extremely low drift rate. Finally, this backup time reference signal generated by the internal clock is seamlessly switched to replace the original global time reference signal, ensuring uninterrupted output of the global time reference signal during satellite time synchronization anomalies.

[0030] In one embodiment, a microgrid system installed in a densely populated urban high-rise area may have its self-synchronizing receiver antenna occasionally and briefly blocked by tall buildings. The preset signal quality requirement is that at least four satellites must be locked. At some point, due to the blockage, the self-synchronizing receiver detects a sharp decrease in the number of visible satellites from six to two, and the BeiDou satellite timing signal quality no longer meets the requirements. The system immediately determines that the primary time source is unreliable. At this time, the highly stable crystal oscillator inside the self-synchronizing receiver, which has been tamed by the BeiDou signal for a long time, automatically enters a "hold" mode, taking over the task of generating the time signal and starting to output a backup time reference signal. The initial time of this backup time reference signal is exactly consistent with the last precise time before the satellite signal was lost, and its frequency hardly drifts for a period of time afterward. Throughout this process, the synchronous operation of the inverter cluster is not interrupted or disturbed until a few seconds later, when the satellite signal is restored, and the system automatically switches back to using the global time reference signal.

[0031] S2. Obtain the real-time operating parameters of each inverter in the microgrid, and calculate the real-time phase offset of each inverter based on the global time reference signal and each real-time operating parameter. like Figure 2 As shown, this is a flowchart illustrating step S2. (Refer to...) Figure 2 Step S2 includes: S201. Real-time operating parameters of each inverter are collected by sensors installed at the output of each inverter in the microgrid. Voltage sensors, frequency sensors, and phase detection sensors are deployed at the AC output terminals of each inverter within the microgrid to collect the electrical operating parameters of each inverter in real time with a sampling period synchronized with the global time reference signal. These electrical operating parameters include the instantaneous value of the inverter's output AC voltage, real-time frequency, output amplitude, and original phase characteristics.

[0032] S202. Extract each real-time operating parameter to obtain the real-time output phase of the corresponding inverter; The real-time operating parameters collected from each inverter are digitally filtered and feature-analyzed. Noise and harmonic interference in the collected signals are removed by a phase-locked loop algorithm. The real-time output phase that can characterize the actual output state of the inverter is extracted from the filtered operating parameters.

[0033] S203. Based on the global time reference signal, calculate the real-time reference phase that all inverters should reach; Based on the absolute time scale provided by the global time reference signal, the real-time reference phase shared by all inverters is calculated using a unified formula: in, express Real-time reference phase at any given moment Indicates the rated frequency of the microgrid system. This represents the current absolute timestamp obtained from the global time base signal. This indicates the start time of system synchronization, typically the time corresponding to the first global time reference signal at system startup or the start of synchronization. This indicates the initial phase offset, which can be set according to system requirements. It is usually 0 or a fixed value to ensure phase continuity.

[0034] S204. Perform differential operation between each real-time output phase and the real-time reference phase to obtain the real-time phase offset of the corresponding inverter.

[0035] Substituting the real-time output phase and real-time reference phase of a single inverter into the differential calculation formula, we obtain the real-time phase offset of the inverter. The calculation formula is as follows: in, Indicates the first Taiwan inverter Real-time phase offset at any given moment. Indicates the first Taiwan inverter The actual output phase at any given moment. This offset directly reflects the magnitude of the deviation between the inverter's actual output and the ideal synchronous phase.

[0036] S3. Based on each real-time phase offset, generate the corresponding synchronous phase angle of the inverter; Each real-time phase offset is filtered, and each filtered real-time phase offset is integrated to obtain the synchronous phase angle of the corresponding inverter.

[0037] Specifically, the real-time phase offset corresponding to each inverter is subjected to low-pass filtering in sequence to filter out high-frequency noise and random interference components in the phase offset, so as to obtain a smooth and stable filtered real-time phase offset.

[0038] Furthermore, an integral operation is used to calculate the phase accumulation of the filtered real-time phase offset. The integral operation formula is as follows: in, Indicates in The synchronization phase angle generated at each moment, This represents the integral gain, which is a pre-set adjustment parameter used to control the rate of integral action. Its value is determined through experiments during the system debugging phase, and is typically set to 0.5. This represents the real-time phase offset after filtering; it is the input for the integration operation. It is the time variable for integration operations.

[0039] Since all inverters use a unified integration reference and initial phase setting, the synchronization phase angle values ​​of each inverter obtained after filtering and integration are completely consistent. This unified synchronization phase angle can be used as the global synchronization phase angle of the entire inverter group to achieve phase synchronization control of all inverters.

[0040] In one embodiment, a microgrid system sets its rated frequency. The frequency is 50Hz, and the current absolute timestamp is determined by the global time base signal at the beginning of a certain control cycle. The system synchronization start time is 10.02 seconds. The initial phase shift is 10.00s. Set it to 0. Calculate the real-time reference phase based on the above parameters. This translates to approximately 360 degrees, meaning it returns to the 0-degree position. Simultaneously, sensors acquire real-time operating parameters of inverter #1, measuring its current actual output phase. for The value is approximately -2 degrees. Then, the real-time phase offset of the inverter is calculated. .

[0041] To eliminate measurement noise, the phase offset is filtered to obtain a smoothed phase offset. Finally, the filtered phase offset is integrated, with the integration gain set to 0.5. By accumulating the error on the time axis, the synchronization phase angle of inverter No. 1 is generated as the final control target.

[0042] To ensure phase synchronization, voltage stability, and uninterrupted power supply during microgrid operation mode switching, a closed-loop control process for mode switching prediction and phase pre-adjustment is added after global phase synchronization adjustment is completed.

[0043] Specifically, after step S3, the following is also included: 1) Acquire the operating status data of each inverter and monitor the status indicators of the microgrid's common coupling point; By deploying DC voltage sensors, output current sensors, internal temperature sensors, and fault detection units inside each inverter, operational status data reflecting the inverter's health and operating conditions are continuously collected, including DC side voltage, output current, internal temperature, switching frequency, and fault codes. Simultaneously, through power quality monitoring devices deployed at the common coupling point between the microgrid and the main grid, real-time status indicators of the common coupling point are collected, including three-phase voltage amplitude, grid frequency, power flow direction, and grid-connected switch status.

[0044] 2) Based on the status indicators of the common coupling point, determine whether the microgrid is about to enter the operation mode switching state; The real-time collected status indicators of the common coupling point are compared with the preset mode switching trigger conditions. The preset mode switching trigger conditions include the main grid voltage dropping below 85% of the rated value, the grid frequency exceeding the range of 49.5Hz to 50.5Hz, the receipt of a planned islanding / grid connection switching command, and a main grid fault signal.

[0045] If the status index of the common coupling point meets any trigger condition and the duration exceeds the preset anti-jitter delay (50ms~200ms), it is determined that the microgrid is about to enter the operation mode switching state; if the trigger condition is not met, it is determined that the microgrid is in the normal grid-connected / islanded stable operation state, and the subsequent mode switching prediction process is not initiated.

[0046] 3) When it is determined that the microgrid is about to enter the operation mode switching state, the operation mode switching time of the corresponding inverter is predicted based on the global time base signal and the data of each operation state; Using the global time reference signal as the absolute time scale, and combining real-time collected operating status data of each inverter, common coupling point status indicators, and historical mode switching record datasets, an operating mode switching time prediction model is constructed.

[0047] Specifically, key features such as voltage drop rate, frequency offset amplitude, and handover delay duration for each historical handover scenario are extracted from the historical mode handover record dataset to construct a standardized historical handover scenario feature library; simultaneously, the real-time common coupling point status index set and the first Taiwan inverter real-time operating status data Feature extraction and normalization are performed to generate a feature sequence for the current operating scenario. Using a global time reference signal as the absolute time calibration basis, the standardized historical switching scenario feature library and the feature sequence of the current operating scenario are used as model inputs, with the mode switching time of a single inverter as the output target, to complete the construction of the operating mode switching time prediction model. The model calculation formula is as follows: in, Indicates the first Predicted operating mode switching time for the inverter. This indicates the initial moment when the state index of the common coupling point meets the triggering condition. This refers to a handover time prediction algorithm based on historical scene matching, trend extrapolation, and real-time operating conditions. This represents the dataset containing historical mode switching records. This represents the feature sequence of the current running scenario.

[0048] The following describes the handover time prediction algorithm. The implementation process will be explained in detail: The similarity calculation formula is used to calculate the matching degree between the feature sequence of the current running scene and the feature sequences of each historical scene. The similarity calculation formula is as follows: in, Feature sequences representing the current running scenario With the A sequence of historical scene features similarity, Indicates a historical scene index. Representing feature dimension, Representing the historical scene eigenvalues, Indicates the current running scenario number eigenvalues.

[0049] Determine the optimal matching historical scene with the highest similarity, extract the predicted switching delay time corresponding to this scene, and substitute the predicted switching delay time into the model calculation formula to obtain the first matching historical scene. Taiwan inverter operating mode switching prediction time The predicted handover delay time is the output of the handover time prediction algorithm, and the optimal matching historical scenario is determined using the following formula: in, This represents the best matching historical scenario. Indicates the number of historical scenes.

[0050] 4) Based on the switching time of each operating mode, the synchronous phase angle of the corresponding inverter is adjusted in advance.

[0051] Using the predicted operating mode switching time of each unit as the time reference, a synchronous phase pre-adjustment closed-loop model is constructed by combining it with the global time reference signal. The model calculation formula is as follows: in, Indicates the first The synchronized phase angle of the inverter after pre-adjustment. The first time before mode switching The original synchronous phase angle of the inverter, Indicates the first Synchronous phase pre-adjustment of the inverter.

[0052] It should be noted that, Dynamic calculations are performed based on the mode switching type (grid-connected to islanded / islanded to grid-connected), global time base synchronization timing, inverter real-time load, and common coupling point phase base.

[0053] Specifically, the synchronization phase pre-adjustment amount Scenario-based weighted calculation is adopted: When switching from grid connection to islanded operation, the following formula is used for calculation: in, Indicates the real-time phase at the common coupling point. Indicates the phase of the global time base. Indicates the first Real-time active power of the inverter. This indicates the rated active power of the inverter. , Indicates the weighting coefficient. The value ranges from 0.6 to 0.9, prioritizing rapid phase tracking and synchronization. The value ranges from 0.1 to 0.3, and is used to adapt to the small correction of phase pre-adjustment by active load, so as to meet the control requirements of smooth phase transition in the grid-connected to islanded scenario.

[0054] When converting an isolated grid to a grid-connected grid, the following formula is used for calculation: in, Indicates the standard phase of the main power grid. Indicates the current phase of the island. Indicates the first Real-time reactive power of the inverter This indicates the rated reactive power of the inverter. , Indicates the weighting coefficient. The value ranges from 0.7 to 1.0 to ensure that the inverter output phase is aligned with the standard phase of the main power grid. The value ranges from 0.05 to 0.2 and is used for reactive power auxiliary voltage regulation and fine-tuning.

[0055] Before the operating mode switching time arrives, smooth phase pre-adjustment is completed, so that the inverter synchronous phase angle smoothly transitions from following the main grid phase reference to following the microgrid's internal global time reference phase reference, eliminating phase step, voltage fluctuation and frequency impact at the moment of switching, and realizing a smooth transition throughout the entire mode switching process.

[0056] S4. Obtain the real-time load change of each inverter, and generate the initial phase adjustment command for the corresponding inverter based on each real-time load change and the global synchronization phase angle. like Figure 3 As shown, this is a flowchart illustrating step S4. (Refer to...) Figure 3 Step S4 includes: S401. The real-time load change of each inverter is obtained by the sensor installed at the output of each inverter in the microgrid. By installing energy metering sensor modules at the output of each inverter in the microgrid, the active and reactive power output of each inverter is continuously monitored in real time. Based on the difference between the monitored instantaneous power value and the reference power value, the real-time load change of each inverter is calculated.

[0057] S402. Each real-time load change is converted into the corresponding inverter's correction phase through droop control. The real-time load change of each inverter is input into the droop control algorithm. Based on the droop control strategy, the dynamic feedback adjustment quantity representing the load fluctuation is transformed into a correction phase used to compensate for load disturbances and achieve stable power distribution. This correction phase is a small dynamic correction of the global synchronization reference phase, which can adapt to the phase adjustment requirements brought about by the real-time load change of the inverter.

[0058] It should be noted that the droop control algorithm is a distributed collaborative control algorithm that simulates the active-frequency and reactive-voltage droop characteristics of traditional synchronous generators. It does not require a centralized controller or interconnection communication. It can autonomously and dynamically adjust the output phase and power distribution ratio according to the real-time load changes of each inverter, converting real-time load fluctuations into corresponding correction phases to compensate for load disturbances, and realizing autonomous collaborative power sharing and phase synchronization among multiple inverters.

[0059] S403. Each correction phase is superimposed with the global synchronization phase angle to obtain the initial phase adjustment command for the corresponding inverter.

[0060] The correction phase generated by the droop control of each inverter is linearly superimposed with the global synchronization phase angle provided by the microgrid system to generate the initial phase adjustment command for the corresponding inverter.

[0061] S5. Obtain the real-time interactive data of each inverter, and update each initial phase adjustment command based on the real-time interactive data and the global synchronization phase angle to obtain the target phase adjustment command of the corresponding inverter. like Figure 4 As shown, this is a flowchart illustrating step S5. (Refer to...) Figure 4 Step S5 includes: S501. Real-time interactive data of each inverter is obtained through a sensor communication network deployed in the microgrid and covering the entire inverter cluster. By deploying a distributed sensor and communication network within the microgrid and covering the entire inverter cluster, interactive data such as instantaneous power exchange between inverters, output terminal voltage difference, and operating status information are collected in real time.

[0062] S502. Based on each real-time interactive data and the global synchronization phase angle, generate the corresponding optimization adjustment command for the inverter; Using the global synchronization phase angle as the absolute ideal reference, the real-time interactive data of each inverter is input into the collaborative optimization control algorithm. This algorithm analyzes the interactive data to identify suboptimal operating states of the inverter cluster caused by line impedance imbalance, uneven power distribution, reactive circulating current, and increased internal losses. It calculates targeted differential correction fine-tuning amounts and finally generates optimized adjustment commands to compensate for cluster operating deviations and suppress reactive circulating current, ensuring efficient collaborative operation of the inverter cluster.

[0063] To facilitate understanding, the implementation process of the collaborative optimization control algorithm will be explained in detail below: The real-time interactive data of each inverter is analyzed to extract key operating characteristics such as reactive current circulation magnitude, power distribution deviation, line impedance difference, and phase offset, identifying abnormal operating states such as reactive current circulation and uneven power distribution in the inverter cluster. Using the global synchronization phase angle as the absolute ideal benchmark, the phase deviation value of the abnormal inverters is calculated to locate the main causes of reactive current circulation (such as phase imbalance caused by line impedance difference).

[0064] Based on the anomaly level and real-time interactive data, an equivalent reverse phase correction is calculated for inverters with reactive power circulating current. For inverters without operational anomalies, the correction is set to zero to ensure that the correction accurately matches the reactive power circulating current suppression requirements. Finally, the calculated phase correction values ​​for each inverter are encapsulated into standardized optimization adjustment instructions for subsequent updates and corrections to the initial phase adjustment instructions.

[0065] S503. Superimpose each initial phase adjustment command and the corresponding optimized adjustment command to obtain the target phase adjustment command for the corresponding inverter.

[0066] A linear superposition update method is used, which numerically superimposes the initial phase adjustment command and the optimized adjustment command. The calculation formula is as follows: in, Indicates the target phase adjustment command. This indicates the initial phase adjustment command. This indicates an optimization / adjustment instruction.

[0067] By superimposing and updating, the target phase adjustment command that adapts to the needs of cluster collaborative operation is obtained, effectively suppressing reactive circulating current and realizing balanced power distribution and efficient and stable operation of the inverter cluster.

[0068] In one embodiment, a microgrid system consists of three inverters operating in parallel, all supplying power to the load. The system has generated initial phase adjustment commands for each inverter to balance the distribution of active power. However, slightly different cable lengths connecting the three inverters to the common combiner point result in minor differences in line impedance. By acquiring real-time interactive data, the system detects that inverter #2 is transferring reactive power to inverter #3, while inverter #1 remains unaffected. This reactive power exchange between inverters is called reactive circulating current; it does not contribute to the load but instead increases system losses.

[0069] At this point, the collaborative optimization control algorithm is activated. It identifies the reactive power circulation and generates an optimization adjustment command based on the interactive data. This command includes adding a very small positive correction to the phase target of inverter 2, applying an equal negative correction to the phase target of inverter 3, and zero correction to inverter 1. Then, this optimization adjustment command updates the original initial phase adjustment command, issuing slightly different target phase adjustment commands to inverters 2 and 3. This tiny phase difference adjustment alters the direction and magnitude of reactive power flow between them, effectively suppressing reactive power circulation and making the inverter cluster operate more efficiently.

[0070] S6. Adjust the output voltage of the corresponding inverter using each target phase adjustment command.

[0071] Each target phase adjustment command is sent to the corresponding inverter so that each inverter adjusts the phase and frequency of its output voltage based on the corresponding target phase adjustment command.

[0072] Specifically, the target phase adjustment command, which includes global synchronization reference and phase correction information, is digitally encoded and sent to the local controller of each inverter through the microgrid high-speed communication network. After receiving the command, the local controller of the inverter analyzes the reference phase, correction phase and frequency adjustment parameters in the command in real time, and immediately adjusts the generation logic of the internal pulse width modulation signal to change the phase and frequency of the inverter output AC voltage, so that the phase and frequency of the output voltage are completely matched with the requirements of the target phase adjustment command, thereby realizing the output phase synchronization and power balance distribution of the inverter cluster.

[0073] This invention discloses a microgrid inverter synchronization method based on satellite timing. It generates a high-precision global time reference through preprocessing of satellite timing signals, eliminating phase accumulation errors caused by local clock drift at the source and ensuring complete uniformity of the synchronization phase angle of each inverter. By combining real-time inverter operating parameters to calculate phase offset and generate a global synchronization phase angle, it achieves precise phase and frequency synchronization of the output voltage of multiple inverters. Based on real-time load changes, it generates initial phase adjustment commands, enabling rapid response to load fluctuations and balanced power distribution. By optimizing and updating the target phase adjustment command using real-time interactive data between inverters, it effectively suppresses reactive power circulating currents between units, achieving cluster collaborative correction without relying on master-slave control and complex communication networks, significantly improving the reliability, power quality, and environmental adaptability of microgrid parallel operation.

[0074] like Figure 5 The diagram shown is a structural schematic of a microgrid inverter synchronization system based on satellite time synchronization according to an embodiment of the present invention. (Refer to...) Figure 5 An embodiment of the present invention provides a microgrid inverter synchronization system based on satellite timing, comprising: The signal receiving and processing module 01 is used to receive satellite timing signals and preprocess the satellite timing signals to obtain a global time reference signal; Phase offset calculation module 02 is used to obtain the real-time operating parameters of each inverter in the microgrid, and calculate the real-time phase offset of each inverter based on the global time reference signal and each real-time operating parameter. Synchronous phase calculation module 03 is used to generate the synchronous phase angle of the corresponding inverter based on each real-time phase offset. The synchronous phase angle of each inverter is the same and can be used as the global synchronous phase angle. The initial instruction generation module 04 is used to obtain the real-time load change of each inverter and generate the corresponding initial phase adjustment instruction for the inverter based on each real-time load change and the global synchronization phase angle. The initial instruction update module 05 is used to acquire the real-time interactive data of each inverter and update each initial phase adjustment instruction based on the real-time interactive data and the global synchronization phase angle to obtain the target phase adjustment instruction of the corresponding inverter. Inverter cluster execution module 06 is used to adjust the output voltage of the corresponding inverter using each target phase adjustment command.

[0075] It should be noted that the modules in the aforementioned satellite-time-based microgrid inverter synchronization system 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, allowing the processor to call and execute the corresponding operations of each module. For specific limitations regarding the satellite-time-based microgrid inverter synchronization system, please refer to the limitations of the satellite-time-based microgrid inverter synchronization method described above; both have the same function and role, and will not be repeated here.

[0076] In summary, the present invention provides a microgrid inverter synchronization method and system based on satellite timing. By preprocessing satellite timing signals to generate a high-precision global time reference, it eliminates phase accumulation errors caused by local clock drift at the source, ensuring complete uniformity of the synchronization phase angle of each inverter. It calculates phase offsets based on real-time inverter operating parameters and generates a global synchronization phase angle, achieving precise phase and frequency synchronization of the output voltage of multiple inverters. It generates initial phase adjustment commands based on real-time load changes, enabling rapid response to load fluctuations and balanced power distribution. By optimizing and updating the target phase adjustment commands using real-time interactive data between inverters, it effectively suppresses reactive power circulation between units, achieving cluster collaborative correction without relying on master-slave control and complex communication networks, significantly improving the reliability, power quality, and environmental adaptability of microgrid parallel operation.

[0077] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0078] 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 substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A microgrid inverter synchronization method based on satellite time synchronization, characterized in that, include: Receive satellite timing signals and preprocess the satellite timing signals to obtain a global time reference signal; The real-time operating parameters of each inverter in the microgrid are obtained, and the real-time phase offset of each inverter is calculated based on the global time reference signal and each of the real-time operating parameters. Based on each of the real-time phase offsets, a corresponding synchronization phase angle for the inverter is generated, wherein the synchronization phase angles of each inverter are the same and can all be used as global synchronization phase angles; The real-time load change of each inverter is obtained, and an initial phase adjustment command corresponding to the inverter is generated based on each real-time load change and the global synchronization phase angle. The real-time interactive data of each inverter is acquired, and the initial phase adjustment command is updated based on the real-time interactive data and the global synchronization phase angle to obtain the target phase adjustment command for the corresponding inverter. The output voltage of the corresponding inverter is adjusted using each of the target phase adjustment commands.

2. The microgrid inverter synchronization method based on satellite time synchronization according to claim 1, characterized in that, After receiving the satellite timing signal and preprocessing the satellite timing signal to obtain the global time reference signal, the method further includes: The satellite timing signal quality index is continuously monitored. When the satellite timing signal quality index does not meet the preset signal quality requirements, a backup time reference signal is generated through the local clock, and the backup time reference signal is used as the global time reference signal.

3. The microgrid inverter synchronization method based on satellite time synchronization according to claim 1, characterized in that, After generating the corresponding synchronization phase angle of the inverter based on each of the real-time phase offsets, the method further includes: Acquire the operating status data of each inverter and monitor the status indicators of the common coupling point of the microgrid; Based on the common coupling point status index, it is determined whether the microgrid is about to enter the operation mode switching state; When it is determined that the microgrid is about to enter the operation mode switching state, the operation mode switching time of the corresponding inverter is predicted based on the global time reference signal and each operation state data. Based on the switching time of each operating mode, the synchronization phase angle of the corresponding inverter is pre-adjusted.

4. The microgrid inverter synchronization method based on satellite time synchronization according to claim 1, characterized in that, The process of receiving satellite timing signals and preprocessing the satellite timing signals to obtain a global time reference signal includes: Satellite timing signals are received by a self-synchronizing receiver deployed in a microgrid, and the satellite timing signals are preprocessed by the self-synchronizing receiver to obtain a global time reference signal. The preprocessing includes extracting time codes, transmission delay compensation, and signal shaping.

5. The microgrid inverter synchronization method based on satellite time synchronization according to claim 1, characterized in that, The process of acquiring the real-time operating parameters of each inverter within the microgrid, and calculating the real-time phase offset of each inverter based on the global time reference signal and each of the real-time operating parameters, includes: Real-time operating parameters of each inverter are collected by sensors installed at the output of each inverter in the microgrid. Each of the aforementioned real-time operating parameters is extracted to obtain the corresponding real-time output phase of the inverter; Based on the global time reference signal, calculate the real-time reference phase that all the inverters should achieve; Each of the real-time output phases is differentially calculated with the real-time reference phase to obtain the real-time phase offset of the corresponding inverter.

6. The microgrid inverter synchronization method based on satellite time synchronization according to claim 1, characterized in that, The step of generating the corresponding synchronization phase angle of the inverter based on each of the real-time phase offsets includes: Each of the real-time phase offsets is filtered, and each filtered real-time phase offset is integrated to obtain the corresponding synchronous phase angle of the inverter.

7. The microgrid inverter synchronization method based on satellite time synchronization according to claim 1, characterized in that, The step of acquiring the real-time load change of each inverter and generating an initial phase adjustment command corresponding to the inverter based on each real-time load change and the global synchronization phase angle includes: The real-time load change of each inverter is obtained by a sensor installed at the output of each inverter in the microgrid. Each of the real-time load changes is converted into the corresponding correction phase of the inverter through droop control. Each of the correction phases is superimposed on the global synchronization phase angle to obtain the initial phase adjustment command for the corresponding inverter.

8. The microgrid inverter synchronization method based on satellite time synchronization according to claim 1, characterized in that, The step of acquiring real-time interactive data for each inverter and updating each initial phase adjustment command based on the real-time interactive data and the global synchronization phase angle to obtain the target phase adjustment command for the corresponding inverter includes: Real-time interactive data of each inverter is acquired through a sensor communication network deployed within the microgrid and covering the entire inverter cluster. Based on each of the real-time interactive data and the global synchronization phase angle, an optimization adjustment command corresponding to the inverter is generated. Each initial phase adjustment command and its corresponding optimized adjustment command are superimposed to obtain the target phase adjustment command for the inverter.

9. The microgrid inverter synchronization method based on satellite time synchronization according to claim 1, characterized in that, The step of adjusting the output voltage of the corresponding inverter using each of the target phase adjustment commands includes: Each target phase adjustment command is sent to the corresponding inverter so that each inverter adjusts the phase and frequency of its output voltage based on the corresponding target phase adjustment command.

10. A microgrid inverter synchronization system based on satellite time synchronization, characterized in that, include: The signal receiving and processing module is used to receive satellite timing signals and preprocess the satellite timing signals to obtain a global time reference signal; The phase offset calculation module is used to obtain the real-time operating parameters of each inverter in the microgrid, and calculate the real-time phase offset of each inverter based on the global time reference signal and each of the real-time operating parameters. The synchronization phase calculation module is used to generate the synchronization phase angle of the corresponding inverter based on each of the real-time phase offsets, wherein the synchronization phase angle of each inverter is the same and can be used as the global synchronization phase angle. An initial instruction generation module is used to obtain the real-time load change of each inverter and generate an initial phase adjustment instruction corresponding to the inverter based on each real-time load change and the global synchronization phase angle. The initial instruction update module is used to acquire real-time interactive data of each inverter and update each initial phase adjustment instruction based on the real-time interactive data and the global synchronization phase angle to obtain the target phase adjustment instruction corresponding to the inverter. The inverter cluster execution module is used to adjust the output voltage of the corresponding inverter using each of the target phase adjustment commands.

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