Bidirectional inverter system for high-altitude power grid and implementation method thereof

Abstract

The invention belongs to the technical field of power equipment, and provides a bidirectional inverter system for a high-altitude power grid and an implementation method of the bidirectional inverter system. The system comprises an STM32F474 main control chip, a six-switch three-phase half-bridge inverter circuit based on gallium nitride, an LCL filter circuit, a harmonic detection and control subsystem, a current inner loop controller, a drive circuit, a wireless communication module and a sampling resistor. The method comprises the steps of direct current conversion, high-frequency filtering, signal acquisition, harmonic detection and optimization and controller regulation and control. According to the invention, through the second-order generalized integrator, the synchronous reference coordinate transformation and the low-pass filter, synchronous detection of signals is realized, and the purity of the signals is ensured; by combining a PI controller and an RC repetitive controller, harmonic suppression is optimized; through SPWM wave control, the problem of three-phase imbalance is solved, and the performance and the stability of the system are improved; and through the wireless communication module, remote control is realized, and the complexity of field maintenance is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power equipment, and in particular to a bidirectional inverter system for a high-altitude power grid and an implementation method thereof. Background Art

[0002] In high-altitude pastoral areas, power equipment faces problems such as harmonic pollution and three-phase imbalance. The widespread access of solar power stations and other renewable energy sources has increased the nonlinear load in power equipment, resulting in the generation of harmonic currents, which in turn cause voltage harmonics. This not only affects the quality of power, but may also cause equipment overheating and damage. The power grid structure in high-altitude pastoral areas is relatively simple, and the load distribution is uneven, resulting in serious three-phase imbalance problems. This situation not only reduces the operating efficiency of the equipment, but also increases line losses and has an adverse impact on the normal operation of the equipment. In addition, the air in the high-altitude environment is thin, the heat dissipation performance of power equipment is reduced, and the climate is changeable and strong ultraviolet radiation, which puts higher requirements on the performance and life of power equipment. Existing harmonic suppression equipment and three-phase imbalance adjustment devices are expensive and difficult to adapt to high altitudes and harsh climatic conditions. At the same time, the installation and maintenance of these equipment require high-level technicians, which are relatively scarce in high-altitude pastoral areas. The intermittent and volatile nature of solar power generation increases the instability of power supply. How to efficiently manage these volatile power sources and ensure the stable operation of the power grid has become an urgent problem to be solved.

[0003] In summary, power equipment in high-altitude pastoral areas faces problems such as harmonic pollution, three-phase imbalance, adaptability to high-altitude environments and renewable energy management. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a bidirectional inverter system for high-altitude power grids and an implementation method thereof, which realizes synchronous detection of signals through a second-order generalized integrator, synchronous reference coordinate transformation and a low-pass filter to ensure the purity of the signal; optimizes harmonic suppression by combining a PI controller and an RC repetitive controller; solves the three-phase imbalance problem through SPWM wave control and improves the performance and stability of the system; and realizes remote control through a wireless communication module to reduce the complexity of on-site maintenance.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A bidirectional inverter system for a high-altitude power grid, comprising: an STM32F474 main control chip, a six-switch three-phase half-bridge inverter circuit based on gallium nitride, an LCL filter circuit, a harmonic detection and control subsystem, a current inner loop controller, a drive circuit, a wireless communication module, and a sampling resistor; the current inner loop controller is embedded with a PI controller and an RC repetitive controller;

[0007] The six-switch three-phase half-bridge inverter circuit is respectively connected to the target optical storage device, the drive circuit and the LCL filter circuit; the STM32F474 main control chip is respectively connected to the current inner loop controller, the harmonic detection and control subsystem and the wireless communication module; the current inner loop controller is also respectively connected to the harmonic detection and control subsystem and the drive circuit; the LCL filter circuit is also connected to the target power grid; the STM32F474 main control chip is respectively connected to the LCL filter circuit and the target power grid through different sampling resistors;

[0008] The six-switch three-phase half-bridge inverter circuit is used to convert the DC power input by the target photovoltaic storage device into three-phase AC power through the three-phase SPWM output by the drive circuit; the LCL filter circuit is used to perform high-frequency filtering on the three-phase AC power to obtain filtered AC power; the STM32F474 main control chip is used to collect the three-phase current signal of the filtered AC power and the grid electrical signal of the target grid, and transmit the three-phase current signal and the grid electrical signal to the current inner loop controller and the harmonic detection and control subsystem respectively; the harmonic detection and control subsystem is used to A second-order generalized integrator, a synchronous reference coordinate transformation and a low-pass filter perform harmonic detection on the grid electrical signal to obtain an optimized current signal, and calculate the difference between the optimized current signal and the grid electrical signal to obtain a command current signal; the current inner loop controller is used to control the three-phase SPWM according to the command current signal and the three-phase current signal using the PI controller and the RC repetitive controller; the three-phase SPWM includes: A-phase SPWM, B-phase SPWM and C-phase SPWM; the wireless communication module is used to control the working mode and perform remote monitoring.

[0009] Preferably, the PI controller and the RC repetitive controller adopt a parallel structure.

[0010] Preferably, the current inner loop controller is integrated with a fuzzy logic control algorithm.

[0011] Preferably, the harmonic detection and control subsystem is integrated with a direct digital frequency synthesis algorithm.

[0012] Preferably, the working mode includes: input voltage range, output power and harmonic compensation strength.

[0013] Preferably, a method for implementing a bidirectional inverter system for a high altitude power grid comprises:

[0014] The direct current input by the target optical storage device is converted into the three-phase alternating current through the three-phase SPWM output by the driving circuit;

[0015] Performing high-frequency filtering on the three-phase alternating current to obtain the filtered alternating current;

[0016] Collecting the three-phase current signal and the grid electrical signal, and transmitting the three-phase current signal and the grid electrical signal to the current inner loop controller and the harmonic detection and control subsystem respectively;

[0017] Performing harmonic detection on the three-phase current signal through the second-order generalized integrator, the synchronous reference coordinate transformation and the low-pass filter to obtain the optimized current signal, and calculating the difference between the optimized current signal and the grid electrical signal to obtain the command current signal;

[0018] The three-phase SPWM is regulated by using the PI controller and the RC repetitive controller according to the command current signal and the three-phase current signal.

[0019] Preferably, the three-phase current signal is subjected to harmonic detection through the second-order generalized integrator, the synchronous reference coordinate transformation and the low-pass filter to obtain the optimized current signal, and the difference between the optimized current signal and the grid electrical signal is calculated to obtain the command current signal, including:

[0020] The grid electrical signal is converted into a two-phase stationary coordinate system by using Clarke transformation, and the fundamental harmonic separation of the three-phase current signal is performed by using the second-order generalized integrator to obtain a separated signal;

[0021] The separated signal is converted into a synchronous rotating coordinate system by using Park transformation, and high-frequency interference in the separated signal is filtered by using the low-pass filter to obtain a fundamental positive sequence component;

[0022] The fundamental positive sequence component is transformed into a Cartesian coordinate system by using an inverse Park transform and an inverse Clarke transform to obtain the optimized current signal, and the optimized current signal is updated in real time by using the synchronous reference coordinate transformation.

[0023] Preferably, it also includes:

[0024] The wireless communication module is used to periodically download the operating parameters stored on the STM32F474 main control chip according to a preset time interval; the operating parameters include: input and output current data, voltage signal data and control signal data;

[0025] The operating parameters are used to optimize the control algorithm and parameters on the STM32F474 main control chip.

[0026] The present invention discloses the following technical effects:

[0027] The present invention provides a bidirectional inverter system for a high-altitude power grid and an implementation method thereof. Through a second-order generalized integrator, a synchronous reference coordinate transformation and a low-pass filter, the harmonic pollution problem is solved and synchronous detection of signals and optimization of signals are realized; through a combination of a PI controller and an RC repetitive controller, the defect of poor harmonic suppression effect of conventional equipment in high-altitude areas is solved and efficient regulation of photovoltaic and energy storage grid connection is realized; through SPWM wave control, the three-phase imbalance problem is solved and reliable conversion of photovoltaic and energy storage is realized; through a wireless communication module, the complexity of on-site maintenance of conventional equipment is solved and remote control is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 A schematic diagram of the structure of a bidirectional inverter system provided by an embodiment of the present invention;

[0030] Figure 2 A signal flow diagram of a harmonic detection and control subsystem provided by an embodiment of the present invention;

[0031] Figure 3 A signal flow diagram of a current inner loop controller provided by an embodiment of the present invention;

[0032] Figure 4 A structural comparison diagram provided for an embodiment of the present invention, Figure 4 (a) is the three-phase current waveform of the power grid. Figure 4 (b) is the three-phase compensation current waveform. Figure 4 (c) is the single-phase voltage and current waveform of the power grid after compensation.

[0033] Description of reference numerals:

[0034] 1-STM32F474 main control chip, 2-harmonic detection and control subsystem, 3-current inner loop controller, 4-drive circuit, 5-six-switch three-phase half-bridge inverter circuit, 6-LCL filter circuit, 7-sampling resistor, 8-wireless communication module. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The purpose of the present invention is to provide a bidirectional inverter system for high-altitude power grids and an implementation method thereof. Through a second-order generalized integrator, a synchronous reference coordinate transformation and a low-pass filter, synchronous detection of signals is achieved to ensure the purity of the signals; by combining a PI controller and an RC repetitive controller, harmonic suppression is optimized; through SPWM wave control, the three-phase imbalance problem is solved to improve the performance and stability of the system; through a wireless communication module, remote control is achieved to reduce the complexity of on-site maintenance.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Figure 1 A schematic diagram of the structure of a bidirectional inverter system provided in an embodiment of the present invention is shown in FIG. Figure 1 As shown, the present invention provides a bidirectional inverter system for high-altitude power grids, including: an STM32F474 main control chip 1, a six-switch three-phase half-bridge inverter circuit 5 based on gallium nitride, an LCL filter circuit 6, a harmonic detection and control subsystem 2, a current inner loop controller 3, a drive circuit 4, a wireless communication module 8 and a sampling resistor 7; the current inner loop controller 3 is embedded with a PI controller and an RC repetitive controller;

[0039] The six-switch three-phase half-bridge inverter circuit 5 is respectively connected to the target optical storage device, the drive circuit 4 and the LCL filter circuit 6; the STM32F474 main control chip 1 is respectively connected to the current inner loop controller 3, the harmonic detection and control subsystem 2 and the wireless communication module 8; the current inner loop controller 3 is also respectively connected to the harmonic detection and control subsystem 2 and the drive circuit 4; the LCL filter circuit 6 is also connected to the target power grid; the STM32F474 main control chip 1 is respectively connected to the LCL filter circuit 6 and the target power grid through different sampling resistors 7;

[0040] The six-switch three-phase half-bridge inverter circuit 5 is used to convert the DC power input by the target optical storage device into three-phase AC power through the three-phase SPWM output by the driving circuit 4; the LCL filter circuit 6 is used to perform high-frequency filtering on the three-phase AC to obtain filtered AC power; the STM32F474 main control chip 1 is used to collect the three-phase current signal of the filtered AC power and the grid electrical signal of the target grid, and transmit the three-phase current signal and the grid electrical signal to the current inner loop controller 3 and the harmonic detection and control subsystem 2 respectively; the harmonic detection and control subsystem 2 is used to perform harmonic detection on the grid electrical signal through a second-order generalized integrator, synchronous reference coordinate transformation and a low-pass filter to obtain an optimized current signal, and calculate the difference between the optimized current signal and the grid electrical signal to obtain a command current signal; the current inner loop controller 3 is used to control the three-phase SPWM using a PI controller and an RC repetitive controller according to the command current signal and the three-phase current signal; the three-phase SPWM includes: A-phase SPWM, B-phase SPWM and C-phase SPWM; the wireless communication module 8 is used to control the working mode and perform remote monitoring.

[0041] Preferably, the PI controller and the RC repetitive controller adopt a parallel structure.

[0042] Furthermore, the current inner loop controller 3 is integrated with a fuzzy logic control algorithm.

[0043] Specifically, the harmonic detection and control subsystem 2 is integrated with a direct digital frequency synthesis algorithm.

[0044] Optionally, the working mode includes: input voltage range, output power and harmonic compensation strength.

[0045] Preferably, a method for implementing a bidirectional inverter system for a high altitude power grid comprises:

[0046] The three-phase SPWM output by the driving circuit 4 converts the DC power input by the target optical storage device into three-phase AC power;

[0047] Perform high-frequency filtering on the three-phase AC to obtain filtered AC power;

[0048] Collect three-phase current signals and grid electrical signals, and transmit the three-phase current signals and grid electrical signals to the current inner loop controller 3 and the harmonic detection and control subsystem 2 respectively;

[0049] The three-phase current signal is subjected to harmonic detection through a second-order generalized integrator, synchronous reference coordinate transformation and a low-pass filter to obtain an optimized current signal, and the difference between the optimized current signal and the power grid electrical signal is calculated to obtain a command current signal;

[0050] The three-phase SPWM is regulated by PI controller and RC repetitive controller according to the command current signal and the three-phase current signal.

[0051] Specifically, the three-phase current signal is subjected to harmonic detection through a second-order generalized integrator, synchronous reference coordinate transformation, and a low-pass filter to obtain an optimized current signal, and the difference between the optimized current signal and the grid electrical signal is calculated to obtain a command current signal, including:

[0052] The Clarke transformation is used to transform the electrical signal of the power grid into a two-phase stationary coordinate system, and the second-order generalized integrator is used to separate the fundamental harmonics of the three-phase current signal to obtain the separated signal.

[0053] The separated signal is converted into a synchronous rotating coordinate system using Park transform, and the high-frequency interference in the separated signal is filtered out using a low-pass filter to obtain the fundamental positive sequence component;

[0054] The fundamental positive sequence component is transformed into a Cartesian coordinate system using inverse Park transform and inverse Clarke transform to obtain an optimized current signal, which is then updated in real time using a synchronous reference coordinate transformation.

[0055] Furthermore, it also includes:

[0056] The wireless communication module 8 is used to download the operating parameters stored in the STM32F474 main control chip 1 at regular intervals according to a preset time interval; the operating parameters include: input and output current data, voltage signal data and control signal data;

[0057] The operating parameters are used to optimize the control algorithm and parameters on the STM32F474 main control chip 1.

[0058] refer to Figure 1 The multifunctional bidirectional inverter system first converts solar energy into direct current through photovoltaic modules, and then converts it into three-phase alternating current through a six-switch three-phase half-bridge inverter using three-way SPWM control, generating a sine wave that matches the grid for grid connection. The LCL filter circuit 6 eliminates high-frequency harmonics to ensure smooth output current. The current inner loop controller 3 adopts a PI control and a repetitive controller parallel structure to dynamically adjust the current, especially to achieve harmonic compensation in the active power filter mode. The main control chip STM32F474 executes a repetitive control algorithm based on the harmonic detection results to modulate the optimal SPWM waveform. Gallium nitride MOSFET is used to enhance the system's ability to adapt to high-altitude environments. The system supports remote mode switching to improve power quality.

[0059] Preferably, GaN material application: The equipment uses wide bandgap GaN MOSFET devices to improve circuit efficiency and stability, adapting to the power requirements and challenges in high-altitude environments. GaN materials have high electron mobility and high breakdown voltage, which enables them to perform well in high-power and high-frequency applications, effectively improving the conversion efficiency of the inverter and reducing energy consumption.

[0060] Specifically, harmonic and three-phase unbalance suppression: harmonic signal extraction reference Figure 2 , which shows the harmonic detection process based on the synchronous reference frame transformation (SRF-PLL) and the second-order generalized integrator (DSOGI) algorithm. First, the system converts the three-phase current signal into a two-phase stationary coordinate system (αβ coordinate system) through Clarke transformation, which simplifies the signal processing process. Then, after the second-order generalized integrator (DSOGI), the algorithm can effectively separate the fundamental and harmonic signals and improve the accuracy of harmonic detection. Then, the system applies Park transformation to the Clarke-transformed signal to transform the signal from the stationary coordinate system to the synchronous rotating coordinate system (dq coordinate system). In this coordinate system, the harmonic signal appears as high-frequency interference, which is convenient for subsequent processing. Subsequently, the signal in the dq coordinate system is processed by a low-pass filter to filter out high-frequency harmonics and retain only the DC component of the fundamental wave. After filtering, the system converts the signal back to the abc coordinate system (Cartesian coordinate system) through inverse Park transformation and inverse Clarke transformation to generate the final three-phase current signal, which can be used for harmonic compensation or further control of grid current. At the same time, the system uses the synchronous reference frame transformation PLL (SRF-PLL) module to track the phase, frequency and voltage amplitude of the power grid in real time to ensure that the system runs synchronously with the power grid, thereby maintaining the stability and response speed of the system. This process can efficiently separate and process harmonic signals, and keep the system synchronized with the power grid through a real-time phase-locked loop, ultimately achieving effective compensation of power grid harmonics and improving power quality. In addition, the PI control and repetitive controller are used in parallel in the current inner loop controller 3 (reference Figure 3 ), the current inner loop control is realized by parallel connection of PI (proportional integral) controller and RC repetitive controller, which effectively suppresses harmonics and three-phase imbalance problems in the power grid and improves the power quality. The PI controller can respond quickly to current changes, and the RC controller can accurately track periodic harmonic signals. The combination of the two ensures effective suppression of harmonics and current balance.

[0061] Furthermore, remote control function: the device is equipped with a WIFI communication module (wireless communication module 8), which can realize remote monitoring and control of the working mode, facilitating operation and maintenance. Through the cloud database, users can monitor the operating status of the device in real time, adjust working parameters, perform fault diagnosis and maintenance, greatly improving the convenience and operability of the device.

[0062] Preferably, three-way SPWM control: The device uses three-way SPWM (Sinusoidal Pulse Width Modulation) control technology for each phase after inversion to ensure the accuracy and stability of the output waveform. SPWM control modulates the carrier frequency to generate an output voltage that is approximately sinusoidal, reducing the harmonic content and improving the power quality.

[0063] Furthermore, the rectifier and active power filter functions: In the rectifier working mode, the SPWM wave modulation acts on the three-phase half-bridge switch to form a resistive load, effectively exerting the filtering function of the active power filter and improving the power quality of the power grid. This function enables the device to flexibly respond to the needs of different working modes and ensure the optimization of power quality under different load conditions.

[0064] Preferably, the equipment structure design and circuit layout are optimized to ensure high efficiency and stability. Reasonable structure design and circuit layout can effectively reduce electromagnetic interference and power loss, and improve the reliability and life of the equipment. Optimization and debugging of control algorithm: ensure the synergy of parallel PI controller and RC controller. Through simulation and experimental verification, optimize control parameters and improve the suppression effect of harmonics and unbalanced currents of the equipment. Integration of WIFI communication module and construction of remote monitoring platform: realize remote control and monitoring of equipment. Integrated communication module and user-friendly monitoring platform make equipment operation more convenient and intelligent. Precise application and parameter adjustment of SPWM control technology: ensure precise control of output waveform and harmonic suppression. Through precise modulation algorithm and parameter optimization, high-quality control of output voltage and current is achieved. Working mode switching and automatic adjustment function of rectifier and active power filter: provide flexible working mode to adapt to different grid conditions. The automatic adjustment function enables the equipment to optimize the working state according to the actual load conditions and improve the power quality.

[0065] Specifically, the bidirectional inverter system of this embodiment is particularly suitable for power systems in high-altitude areas and can effectively cope with technical challenges brought about by environmental changes. Figure 4 , Figure 4 (a) is the grid current waveform. It can be seen that there is significant harmonic distortion in the current before compensation, and the waveform is not smooth. Figure 4 (b) is the compensation current waveform, showing the compensation current generated by the system, which is mainly used to eliminate the harmonic components in the power grid. Figure 4 (c) is the grid voltage and current waveform after compensation, showing the compensation effect. This is a single-phase waveform, showing that the harmonic distortion of the current has been significantly reduced after compensation, the waveform is closer to the ideal sine wave, and the power quality has been improved.

[0066] Preferably, the working principle of this embodiment is: when the bidirectional inverter works in high altitude areas, it uses gallium nitride (GaN) MOSFET devices to improve efficiency and durability, and integrates WIFI communication modules to achieve remote control, reducing the complexity of on-site maintenance. In order to accurately process grid harmonics, Clark transformation is used in combination with DSOGI algorithm and SRF-PLL technology to synchronously detect voltage signals, and low-pass filtering is used to ensure signal purity. Combining PI control with repetitive controllers, harmonic suppression is optimized, and through independent SPWM wave control, the three-phase imbalance problem is effectively controlled, significantly improving the performance and stability of the system.

[0067] Further, the implementation steps are as follows:

[0068] S1: First, install the bidirectional inverter system in a high-altitude environment and ensure the physical connection and environmental adaptability of the equipment. At the same time, ensure that the WIFI communication module works properly and ensures that it is connected to the remote control device. After the installation is completed, the user can remotely access the inverter interface through the WIFI network and set the initial working mode, including key parameters such as input voltage range and output power, to adapt to specific grid requirements. The device sets the working status through the cloud database, WIFI, CAN LAN or manual buttons.

[0069] S2: After starting the inverter, the system starts to monitor the input and output current signals in real time. At this time, the detected three-phase current signal is converted to the α-β stationary coordinate system through Clark transformation to achieve the separation of DC and AC components. The separated signal will be accurately processed by the DSOGI algorithm to extract the fundamental positive sequence component. At the same time, the SRF-PLL technology is used to synchronously detect the input voltage signal to ensure the accurate synchronization and processing of the current and voltage signals, and to ensure the efficient interaction between the power grid and the inverter.

[0070] S3: The signal processed by the DSOGI algorithm is input into a low-pass filter for further signal processing to filter out high-frequency noise and possible electromagnetic interference. This step is intended to ensure the purity of the output signal, provide a reliable basis for subsequent signal control and output, and ensure the stability of system operation. In the grid-connected inverter mode, the device generates a sine wave that matches the phase, frequency, and amplitude of the grid, and injects it into the grid to achieve closed-loop control of the grid-connected power and add a low-pass filter to the repetitive control algorithm and apply the optimal modulation voltage to the SPWM control, so that the main circuit of the typical architecture generates harmonic compensation current.

[0071] S4: In the current inner loop controller 3, a structure in which a PI controller and a repetitive controller are connected in parallel is used to precisely control the processed signal. The PI controller is responsible for basic current control to ensure the response speed and stability of the system, while the repetitive controller focuses on the precise suppression of specific frequency harmonics. Through this joint control structure, the system can more effectively compensate for harmonics in the power grid and improve the overall system operation stability and power quality.

[0072] S5: Use three independent SPWM waves to precisely control the three-phase current. Each SPWM wave controls one phase current of the power grid, independently adjusting and compensating the unbalanced harmonics in each phase. Subsequently, the system converts the control signal into a three-phase fundamental current signal through inverse Clark and inverse Park transformations, and compares it with the actual current in the power grid. The difference is used as an accurate command current signal and input into the current inner loop controller 3, providing a reliable basis for regulation for the system, thereby achieving effective control of harmonics and unbalanced problems. Specifically, the harmonic current information is detected by the harmonic detection method to obtain the harmonic current component. Based on the harmonic current component, the repetitive control algorithm is executed on the typical architecture in advance of the preset time, and the partial derivative of the value function and the modulation voltage at the previous moment of the preset time is calculated to obtain the optimal modulation voltage; wherein the harmonic control method uses a parallel PI controller and an RC repetitive controller, and uses three SPWM waves to control each phase. In the energy storage rectification mode, the device acts on the three-phase half-bridge switch through SPWM wave modulation, presenting a resistive load and playing the role of an active power filter. In the active power filter harmonic control mode, the device disconnects the DC side from the energy storage device and photovoltaic battery device, and modulates the SPWM wave to the switch tube side through the harmonic detection algorithm to improve the power quality of the high-altitude pastoral power grid.

[0073] S6: During system operation, users can monitor the working status of the inverter in real time through the WIFI network. According to the monitoring data and changes in grid demand, users can remotely adjust the working mode and parameter settings of the inverter, including adjusting the output power, changing the harmonic compensation strength, etc., to ensure the continuous and efficient operation of the system in a high-altitude environment and meet dynamic power needs.

[0074] S7: To ensure the long-term and efficient operation of the system, regularly download system operation data, including input and output current, voltage signals, and control signals. Analyze these data to identify potential performance optimization points. Based on the analysis results, further optimize the control algorithm and parameter settings, continuously improve the operating efficiency and stability of the system, and ensure the reliability and performance durability of the inverter in high-altitude environments.

[0075] Optionally, S2 can also use a direct digital synthesis (DDS) algorithm to generate the inverter output waveform. The DDS algorithm can accurately control the frequency and phase of the output waveform, thereby further improving the adaptability and stability of the inverter in high-altitude power grids, especially showing higher accuracy and consistency when the frequency fluctuates.

[0076] Optionally, S4 can also use fuzzy logic control (FLC) algorithm to optimize the inverter output power and current control strategy in real time. Through the FLC algorithm, the system can better cope with the rapid changes in grid load in high altitude areas, further improve the overall efficiency and reliability of the system, and ensure stable operation under complex power conditions.

[0077] The beneficial effects of the present invention are as follows:

[0078] The present invention realizes synchronous detection of signals through second-order generalized integrators, synchronous reference coordinate transformation and low-pass filters to ensure signal purity; optimizes harmonic suppression by combining PI controllers and RC repetitive controllers; solves the three-phase imbalance problem through SPWM wave control and improves system performance and stability; realizes remote control through wireless communication modules and reduces the complexity of on-site maintenance. The present invention provides an efficient, stable, intelligent and multifunctional bidirectional inverter system by integrating advanced materials, control technologies and remote monitoring functions, which can significantly improve the stability and power quality of high-altitude pastoral power grid equipment and reduce equipment operating costs.

[0079] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0080] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A bidirectional inverter system for a high altitude power grid, characterized in that: include: STM32F474 main control chip, six-switch three-phase half-bridge inverter circuit based on gallium nitride, LCL filter circuit, harmonic detection and control subsystem, current inner loop controller, drive circuit, wireless communication module and sampling resistor; the current inner loop controller is embedded with PI controller and RC repetitive controller; The six-switch three-phase half-bridge inverter circuit is respectively connected to the target optical storage device, the drive circuit and the LCL filter circuit; the STM32F474 main control chip is respectively connected to the current inner loop controller, the harmonic detection and control subsystem and the wireless communication module; the current inner loop controller is also respectively connected to the harmonic detection and control subsystem and the drive circuit; the LCL filter circuit is also connected to the target power grid; the STM32F474 main control chip is respectively connected to the LCL filter circuit and the target power grid through different sampling resistors; The six-switch three-phase half-bridge inverter circuit is used to convert the direct current input by the target photovoltaic storage device into three-phase alternating current through the three-phase SPWM output by the drive circuit; the LCL filter circuit is used to perform high-frequency filtering on the three-phase alternating current to obtain filtered alternating current; the STM32F474 main control chip is used to collect the three-phase current signal of the filtered alternating current and the grid electrical signal of the target grid, and transmit the three-phase current signal and the grid electrical signal to the current inner loop controller and the harmonic detection and control subsystem respectively; the harmonic detection and control subsystem is used to perform harmonic detection on the grid electrical signal through a second-order generalized integrator, synchronous reference coordinate transformation and a low-pass filter to obtain an optimized current signal, and calculate the difference between the optimized current signal and the grid electrical signal to obtain a command current signal; the current inner loop controller is used to use the PI controller and the RC repetitive controller to regulate the three-phase SPWM according to the command current signal and the three-phase current signal; the three-phase SPWM includes: A-phase SPWM, B-phase SPWM and C-phase SPWM; The wireless communication module is used to adjust the working mode and perform remote monitoring.

2. A bidirectional inverter system for a high altitude power grid according to claim 1, characterized in that: The PI controller and the RC repetitive controller adopt a parallel structure.

3. A bidirectional inverter system for a high altitude power grid according to claim 1, characterized in that: The current inner loop controller is integrated with a fuzzy logic control algorithm.

4. A bidirectional inverter system for a high altitude power grid according to claim 1, characterized in that: The harmonic detection and control subsystem is integrated with a direct digital frequency synthesis algorithm.

5. A bidirectional inverter system for a high altitude power grid according to claim 1, characterized in that: The working mode includes: input voltage range, output power and harmonic compensation strength.

6. A method for implementing a bidirectional inverter system for a high altitude power grid, characterized in that The method applied to the bidirectional inverter system for a high altitude power grid according to claim 1 comprises: The direct current input by the target optical storage device is converted into the three-phase alternating current through the three-phase SPWM output by the driving circuit; Performing high-frequency filtering on the three-phase alternating current to obtain the filtered alternating current; Collecting the three-phase current signal and the grid electrical signal, and transmitting the three-phase current signal and the grid electrical signal to the current inner loop controller and the harmonic detection and control subsystem respectively; Performing harmonic detection on the three-phase current signal through the second-order generalized integrator, the synchronous reference coordinate transformation and the low-pass filter to obtain the optimized current signal, and calculating the difference between the optimized current signal and the grid electrical signal to obtain the command current signal; The three-phase SPWM is regulated by the PI controller and the RC repetitive controller according to the command current signal and the three-phase current signal.

7. The method for implementing a bidirectional inverter system for a high altitude power grid according to claim 6, characterized in that: The three-phase current signal is subjected to harmonic detection through the second-order generalized integrator, the synchronous reference coordinate transformation and the low-pass filter to obtain the optimized current signal, and the difference between the optimized current signal and the grid electrical signal is calculated to obtain the command current signal, including: The grid electrical signal is converted into a two-phase stationary coordinate system by using Clarke transformation, and the fundamental harmonic separation of the three-phase current signal is performed by using the second-order generalized integrator to obtain a separated signal; The separated signal is converted into a synchronous rotating coordinate system by using Park transformation, and high-frequency interference in the separated signal is filtered by using the low-pass filter to obtain a fundamental positive sequence component; The fundamental positive sequence component is transformed into a Cartesian coordinate system by using an inverse Park transform and an inverse Clarke transform to obtain the optimized current signal, and the optimized current signal is updated in real time by using the synchronous reference coordinate transformation.

8. The method for implementing a bidirectional inverter system for a high-altitude power grid according to claim 6, characterized in that: Also includes: Regularly downloading the operating parameters stored on the STM32F474 main control chip using the wireless communication module at preset time intervals; The operating parameters include: input and output current data, voltage signal data and control signal data; The operating parameters are used to optimize the control algorithm and parameters on the STM32F474 main control chip.

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