A phase synchronization method for energy storage inverters based on half-angle characteristics

Abstract

This application discloses a phase synchronization method for an energy storage inverter based on half-angle characteristics, comprising: acquiring the input voltage signal from the power grid; locking the phase angle of the input voltage signal using a rotating coordinate method; obtaining the sine and cosine values ​​of the rotation angle of the input voltage signal based on the phase angle of the input voltage signal; converting the sine and cosine values ​​of the input and output voltage signals into half-angle forms according to the half-angle characteristic formula; converting the half-angle forms into the sine and cosine values ​​of the phase angle difference between the input and output voltage signals according to the two-angle sum formula; and using PI control to adjust the phase of the output voltage signal by using the sine value of the phase angle difference as an input quantity. This application achieves phase synchronization of the inverter with the power grid before grid connection, reduces the phase difference between the inverter synchronization signal and the power grid signal, reduces the current generated by the voltage difference during grid connection, and improves the stability of the inverter.

Description

Technical Field

[0001] This application relates to the field of photovoltaic energy storage inverters, and in particular to a phase synchronization method for energy storage inverters based on half-angle characteristics. Background Technology

[0002] Photovoltaic energy storage inverters have the function of supplying power to the grid. How to accurately track the grid phase under grid-connected conditions to reduce errors has become an important research topic. The traditional synchronous square wave method involves the inverter master using a rotating coordinate method to track the grid voltage AC signal, marking the zero-crossing points of the sine phase angle. The slave unit then constructs the phase and frequency of the output voltage signal based on these zero-crossing points. However, traditional phase synchronization methods can lead to discrepancies between the marked phase and the actual phase. This is because the sine value of the AC signal has three zero-crossing points within one cycle, but only two need to be marked. The processor is prone to misjudging these points, causing the marked zero-crossing points to fail to reflect the phase and frequency of the AC signal, resulting in grid phase tracking errors and inconsistencies between the output voltage signal and the grid signal.

[0003] Therefore, the aforementioned technical problems in the relevant technologies urgently need to be solved. Summary of the Invention

[0004] This application aims to solve one of the technical problems in related technologies. To this end, embodiments of this application provide a phase synchronization method for energy storage inverters based on half-angle characteristics, which can realize the master-slave mechanism of the energy storage inverter following the phase of the grid voltage, reducing the situation where the synchronization signal and the actual grid voltage phase differ by half a cycle.

[0005] According to one aspect of the embodiments of this application, a phase synchronization method for an energy storage inverter based on half-angle characteristics is provided, the method comprising:

[0006] The input voltage signal of the power grid is acquired, and the phase angle of the input voltage signal is locked by the rotating coordinate method. The sine and cosine values ​​of the rotation angle of the input voltage signal are obtained based on the phase angle of the input voltage signal.

[0007] According to the half-angle characteristic formula, the sine and cosine values ​​of the input voltage signal and the output voltage signal are converted into sine and cosine values ​​in half-angle form;

[0008] According to the formula for the sum of two angles, the sine and cosine values ​​in half-angle form are converted into the sine value of the phase angle difference between the input voltage signal and the output voltage signal;

[0009] According to PI control, the sine value of the phase angle difference is used as the input quantity to regulate the phase of the output voltage signal.

[0010] In one embodiment, locking the phase angle of the input voltage signal using a rotating coordinate method includes:

[0011] The input voltage signal vector is used as a rotation vector;

[0012] The rotation vector is rotated around the origin, and the coordinate axes rotate synchronously with the rotation vector.

[0013] When the projection value of the rotation vector onto the coordinate axis is zero, the rotation angle of the coordinate axis is obtained;

[0014] The rotation angle of the coordinate axis is used as the phase angle of the input voltage signal.

[0015] In one embodiment, the phase angle of the input voltage signal is locked by the rotating coordinate method using a PID module.

[0016] In one embodiment, the half-angle characteristic formula is:

[0017]

[0018]

[0019] Wherein, θ is the phase angle of the input voltage signal or the phase angle of the output voltage signal.

[0020] In one embodiment, converting the sine and cosine values ​​of the input and output voltage signals into half-angle form, according to the half-angle characteristic formula, includes:

[0021] The phase angle sine and cosine values ​​of the input voltage signal are converted into half-angle sine and cosine values;

[0022] The phase angle sine and cosine values ​​of the output voltage signal are converted into half-angle sine and cosine values.

[0023] In one embodiment, the formula for the sum of the two angles is:

[0024]

[0025] Wherein, α and β are the phase angles of the input voltage signal or the output voltage signal.

[0026] In one embodiment, converting the sine and cosine values ​​in half-angle form into the sine value of the phase angle difference between the input voltage signal and the output voltage signal according to the two-angle sum formula includes:

[0027] The sine and cosine values ​​of the phase angle of the input voltage signal are converted into the sine value of the phase difference in half-angle form.

[0028] The sine and cosine values ​​of the phase angle of the output voltage signal are converted into the sine value of the phase difference in half-angle form.

[0029] In one embodiment, according to PI control, the sine value of the phase angle difference is used as the input quantity to regulate the phase of the output voltage signal. The formula for PI control is:

[0030]

[0031] Where finalstep is the phase of the output voltage, K p and K i As assignment variables, α and β are the phase angles of the input voltage signal or the output voltage signal.

[0032] In one embodiment, the method further includes:

[0033] Input the phase of the output voltage into the PID module;

[0034] The phase of the output voltage signal is controlled by the PID module to synchronize the phase of the input voltage signal and the output voltage signal.

[0035] In one embodiment, after acquiring the input voltage signal of the power grid, the method further includes:

[0036] Set the preset filter frequency;

[0037] The input voltage signal is filtered according to the preset filtering frequency.

[0038] The beneficial effects of the phase synchronization method for energy storage inverters based on half-angle characteristics provided in this application are as follows: This application acquires the input voltage signal from the power grid, locks the phase angle of the input voltage signal using a rotating coordinate method, and obtains the sine and cosine values ​​of the rotation angle of the input voltage signal based on the phase angle of the input voltage signal; according to the half-angle characteristic formula, the sine and cosine values ​​of the input voltage signal and the output voltage signal are converted into sine and cosine values ​​in half-angle form; according to the two-angle sum formula, the sine and cosine values ​​in half-angle form are converted into the sine value of the phase angle difference between the input voltage signal and the output voltage signal; according to PI control, the sine value of the phase angle difference is used as an input quantity to regulate the phase of the output voltage signal. This application achieves phase synchronization of the inverter with the power grid before grid connection, reduces the phase difference between the inverter synchronization signal and the power grid signal, thereby reducing the current generated due to voltage difference during grid connection, reducing losses, and ensuring the stability of inverter operation.

[0039] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 A flowchart illustrating a phase synchronization method for an energy storage inverter based on half-angle characteristics, provided for an embodiment of this application;

[0042] Figure 2 A schematic diagram illustrating the use of the rotating coordinate method to lock the phase angle of the input voltage signal according to an embodiment of this application;

[0043] Figure 3 A schematic diagram illustrating the method for calculating sine and cosine values ​​in half-angle form provided in this application embodiment;

[0044] Figure 4 The diagram shows the effect of a phase synchronization method for an energy storage inverter based on half-angle characteristics, provided in an embodiment of this application. Detailed Implementation

[0045] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0046] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0047] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0048] Photovoltaic energy storage inverters have the function of supplying power to the grid. How to accurately track the grid phase under grid-connected conditions to reduce errors has become an important research topic. The traditional synchronous square wave method involves the inverter master using a rotating coordinate method to track the grid voltage AC signal, marking the zero-crossing points of the sine phase angle. The slave unit then constructs the phase and frequency of the output voltage signal based on these zero-crossing points. However, traditional phase synchronization methods can lead to discrepancies between the marked phase and the actual phase. This is because the sine value of the AC signal has three zero-crossing points within one cycle, but only two need to be marked. The processor is prone to misjudging these points, causing the marked zero-crossing points to fail to reflect the phase and frequency of the AC signal, resulting in grid phase tracking errors and inconsistencies between the output voltage signal and the grid signal.

[0049] To address the aforementioned issues, this application proposes a phase synchronization method for energy storage inverters based on half-angle characteristics.

[0050] To facilitate reading and comprehension, explanations are provided for any technical terms that may appear in this instruction manual, as follows:

[0051] Energy storage inverter: An energy storage inverter is a converter with energy storage function that can convert DC power (batteries, storage batteries) into AC power (typically 220V, 50Hz sine wave) with fixed frequency and voltage or variable frequency and voltage. An energy storage inverter consists of an inverter bridge, control logic, and filter circuitry.

[0052] Half-angle properties: Half-angle properties refer to the phase angle characteristics that conform to the half-angle formula. The half-angle formula is a formula that uses the sine, cosine, tangent, and other trigonometric function values ​​of a given angle to calculate the sine, cosine, tangent, and other trigonometric function values ​​of its half-angle.

[0053] PI control: PI control is a linear control method that uses the control deviation between the given value and the actual output value as a basis. The proportional and integral components of the deviation are then linearly combined to form the control quantity, which is used to control the controlled object.

[0054] PID: The PID module is a component of a PID control system. Automatic adjustment of PID controller parameters is achieved through intelligent adjustment, self-calibration, or adaptive algorithms. There are pressure, temperature, flow, and level controllers that utilize PID control; programmable logic controllers (PLCs) that can implement PID control; and PC systems that can implement PID control, etc. PLCs implement PID control using their closed-loop control modules, and PLCs can be directly connected to ControlNet.

[0055] Figure 1 A flowchart illustrating a phase synchronization method for an energy storage inverter based on half-angle characteristics, as provided in this application embodiment, is shown below. Figure 1 As shown, the phase synchronization method for energy storage inverters based on half-angle characteristics provided in this application includes:

[0056] S101. Acquire the input voltage signal of the power grid.

[0057] In step S101, the input voltage signal collected is the AC voltage signal input from the power grid to the energy storage inverter. The collection method includes, but is not limited to, measuring the voltage by connecting a voltage detection instrument or voltmeter in the loop between the energy storage inverter and the power grid.

[0058] Optionally, after acquiring the input voltage signal from the power grid, the method further includes: setting a preset filtering frequency; and filtering the input voltage signal according to the preset filtering frequency. In this embodiment, the input voltage signal acquired is filtered by a preset frequency, which can effectively filter out noise signals in the energy storage inverter and interference signals caused by power grid fluctuations, improve the stability of the input voltage signal, and improve the accuracy of the phase adjustment results.

[0059] S102. Lock the phase angle of the input voltage signal using the rotating coordinate method.

[0060] In step S102, locking the phase angle of the input voltage signal using the rotating coordinate method specifically includes: using the input voltage signal vector as a rotation vector; rotating the rotation vector around the origin, while the coordinate axis rotates synchronously with the rotation vector; obtaining the rotation angle of the coordinate axis when the projection value of the rotation vector on the coordinate axis is zero; and using the rotation angle of the coordinate axis as the phase angle of the input voltage signal. For this purpose, this description is attached... Figure 2 The operation process of locking the phase angle of the input voltage signal using the rotating coordinate method is explained in detail below:

[0061] like Figure 2As shown, the input voltage signal is taken as the target and can be regarded as a rotating vector v' rotating around the origin. The rotating coordinate axis dq rotates with v', making the projection value of v' on the q-axis 0. At this time, the rotation angle θ of the rotating coordinate axis is the phase angle of the grid voltage AC signal, and the projection value of v' on the d-axis is the amplitude of the grid voltage AC signal. Setting the projection value of v' on the q-axis to 0 is the process of locking the input voltage using the rotating coordinate method. Through the rotation process described in this embodiment, the phase angle of the input voltage can be locked, providing a data basis for subsequent steps based on the phase angle of the input voltage.

[0062] Optionally, in this embodiment, locking the phase angle of the input voltage signal using the rotating coordinate method can be achieved through a PID module. The PID module includes pre-programmed PLC control, and also includes other methods for locking the phase using the rotating coordinate method provided in this embodiment, which will not be described in detail here.

[0063] S103. Obtain the sine and cosine values ​​of the rotation angle of the input voltage signal based on the phase angle of the input voltage signal.

[0064] S104. According to the half-angle characteristic formula, the sine and cosine values ​​of the input voltage signal and the output voltage signal are converted into sine and cosine values ​​in half-angle form.

[0065] In this embodiment, the half-angle characteristic formula is:

[0066]

[0067]

[0068] Wherein, θ is the phase angle of the input voltage signal or the phase angle of the output voltage signal. In this embodiment, according to the half-angle characteristic formula, the sine and cosine values ​​of the input and output voltage signals are converted into half-angle forms. Specifically, this includes: converting the sine and cosine values ​​of the phase angle of the input voltage signal into half-angle forms; and converting the sine and cosine values ​​of the phase angle of the output voltage signal into half-angle forms. That is, after phase-locking using the rotating coordinate method, the phase angle is obtained, and then the phase angle is half-angled according to the above half-angle formula. The feedback output phase angle is also half-angled. Its function is to convert the phase angle into a half-angle, which facilitates the subsequent calculation of the output phase angle and makes it easier to synchronize the input and output phase angles.

[0069] S105. According to the formula for the sum of two angles, the sine and cosine values ​​in half-angle form are converted into the sine value of the phase angle difference between the input voltage signal and the output voltage signal.

[0070] In step S105, the formula for the sum of two angles is:

[0071]

[0072] Wherein, α and β are the phase angles of the input voltage signal or the output voltage signal. This embodiment, based on the two-angle sum formula, converts the sine and cosine values ​​in half-angle form into the sine value of the phase angle difference between the input and output voltage signals. Specifically, this includes: converting the sine and cosine values ​​of the input voltage signal's phase angle into the sine value of the half-angle phase difference; and converting the sine and cosine values ​​of the output voltage signal's phase angle into the sine value of the half-angle phase difference. That is, after phase-locking using the rotating coordinate method, the phase angle is obtained, and then the phase angle is half-angled according to the above two-angle sum formula. The feedback output phase angle is also half-angled. Its function is to convert the phase angle into a half-angle, facilitating subsequent calculation of the output phase angle and ensuring synchronization between the input and output phase angles.

[0073] S106. According to PI control, the sine value of the phase angle difference is used as the input quantity to regulate the phase of the output voltage signal.

[0074] In step S106, according to PI control, the sine value of the phase angle difference is used as the input quantity to regulate the phase of the output voltage signal. The formula for PI control is:

[0075]

[0076] Where finalstep is the phase of the output voltage, K p and K i As assignment variables, α and β are the phase angles of the input voltage signal or the output voltage signal.

[0077] Optionally, in this embodiment, the PI control uses the phase of the output voltage as an input quantity to the PID module; the PID module adjusts the phase of the output voltage signal to synchronize the phase of the input voltage signal and the output voltage signal.

[0078] Figure 3 A schematic diagram illustrating the method for calculating sine and cosine values ​​in half-angle form provided in this application embodiment is shown below. Figure 3As shown, the phase synchronization method for energy storage inverters based on half-angle characteristics in this application first samples the grid voltage, then obtains the phase angle of the input voltage using the rotating coordinate method. After a series of processing steps, including half-angle conversion, two-angle summation, and difference conversion, the phase angle of the output voltage is obtained. It should be noted that the calculated output voltage phase angle is not the actual phase angle of the current output voltage, but rather the phase angle corresponding to the input voltage to maintain phase synchronization. Therefore, it is necessary to use PID control to change the output voltage phase angle to the calculated output voltage phase angle. Finally, the PID controller controls the output voltage phase angle of the energy storage inverter to the calculated phase angle, achieving synchronization of the input and output voltage phase angles of the energy storage inverter.

[0079] Figure 4 The diagram illustrates the effect of a phase synchronization method for an energy storage inverter based on half-angle characteristics, as provided in an embodiment of this application. Figure 4 As shown, this application verifies its reliability through simulation waveform analysis, ensuring the stable realization of the expected functions. Specifically: the topmost curve represents the input voltage waveform before using the half-angle characteristic phase synchronization method for the energy storage inverter provided in this application; the second square wave waveform from the top represents the input voltage waveform after using the half-angle characteristic phase synchronization method; the third square wave waveform from the top represents the output voltage waveform before using the half-angle characteristic phase synchronization method; and the bottom square wave waveform represents the output voltage waveform after using the half-angle characteristic phase synchronization method. Figure 4 As can be seen from the four waveforms, before using the half-angle characteristic phase synchronization method for energy storage inverters provided in this application, the phases of the input voltage waveform and the output voltage waveform are not synchronized, which will lead to sudden changes in frequency or phase and failure to respond to voltage changes in a timely manner. However, after using the half-angle characteristic phase synchronization method for energy storage inverters provided in this application, the phases of the input voltage waveform and the output voltage waveform tend to be synchronized, ensuring stable current output. By accurately tracking the phase of the grid voltage, the voltage difference between the inverter output voltage and the grid voltage is reduced, thereby reducing the oscillation of the current value on the transmission line. When sudden changes in frequency or phase occur, the inverter can respond quickly, improving its control performance, ensuring stable power supply, and reducing the possibility of danger.

[0080] In some alternative embodiments, the functions / operations mentioned in the block diagrams may not occur in the order shown in the operation diagrams. For example, depending on the functions / operations involved, two consecutively shown blocks may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order. Furthermore, the embodiments presented and described in the flowcharts of this application are provided by way of example to provide a more comprehensive understanding of the technology. The disclosed methods are not limited to the operations and logic flows presented herein. Alternative embodiments are contemplated in which the order of various operations is changed and sub-operations described as part of a larger operation are executed independently.

[0081] Furthermore, although this application is described in the context of functional modules, it should be understood that, unless otherwise stated to the contrary, one or more of the functions and / or features may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding this application. Rather, given the properties, functions, and internal relationships of the various functional modules in the apparatus disclosed herein, the actual implementation of the module will be understood within the scope of conventional technology for an engineer. Therefore, those skilled in the art can implement the application set forth in the claims using ordinary techniques without excessive experimentation. It is also understood that the specific concepts disclosed are merely illustrative and not intended to limit the scope of this application, which is determined by the full scope of the appended claims and their equivalents.

[0082] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0083] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0084] In the foregoing description of this specification, the references to terms such as "one embodiment," "another embodiment," or "some embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0085] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

[0086] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A phase synchronization method for an energy storage inverter based on half-angle characteristics, characterized in that, The method includes: The input voltage signal of the power grid is acquired, and the phase angle of the input voltage signal is locked by the rotating coordinate method. The sine and cosine values ​​of the rotation angle of the input voltage signal are obtained based on the phase angle of the input voltage signal. According to the half-angle characteristic formula, the sine and cosine values ​​of the input voltage signal and the output voltage signal are converted into sine and cosine values ​​in half-angle form; According to the formula for the sum of two angles, the sine and cosine values ​​in half-angle form are converted into the sine value of the phase angle difference between the input voltage signal and the output voltage signal; According to PI control, the sine value of the phase angle difference is used as the input quantity to regulate the phase of the output voltage signal.

2. The phase synchronization method for an energy storage inverter based on half-angle characteristics according to claim 1, characterized in that, Locking the phase angle of the input voltage signal using a rotating coordinate method includes: The input voltage signal vector is used as a rotation vector; The rotation vector is rotated around the origin, and the coordinate axes rotate synchronously with the rotation vector. When the projection value of the rotation vector onto the coordinate axis is zero, the rotation angle of the coordinate axis is obtained; The rotation angle of the coordinate axis is used as the phase angle of the input voltage signal.

3. The phase synchronization method for an energy storage inverter based on half-angle characteristics according to claim 1, characterized in that, The phase angle of the input voltage signal is locked using the rotating coordinate method, which is achieved through a PID module.

4. The phase synchronization method for an energy storage inverter based on half-angle characteristics according to claim 1, characterized in that, The formula for the half-angle characteristic is: in, The phase angle of the input voltage signal or the phase angle of the output voltage signal.

5. The phase synchronization method for an energy storage inverter based on half-angle characteristics according to claim 1, characterized in that, According to the half-angle characteristic formula, the sine and cosine values ​​of the input and output voltage signals are converted into half-angle sine and cosine values, including: The phase angle sine and cosine values ​​of the input voltage signal are converted into half-angle sine and cosine values; The phase angle sine and cosine values ​​of the output voltage signal are converted into half-angle sine and cosine values.

6. The phase synchronization method for an energy storage inverter based on half-angle characteristics according to claim 1, characterized in that, The formula for the sum of the two angles is: in, The phase angles of the input voltage signal and the output voltage signal are respectively.

7. The phase synchronization method for an energy storage inverter based on half-angle characteristics according to claim 1, characterized in that, According to the formula for the sum of two angles, the sine and cosine values ​​in half-angle form are converted into the sine value of the phase angle difference between the input voltage signal and the output voltage signal, including: The sine and cosine values ​​of the phase angle of the input voltage signal are converted into the sine value of the phase difference in half-angle form. The sine and cosine values ​​of the phase angle of the output voltage signal are converted into the sine value of the phase difference in half-angle form.

8. The phase synchronization method for an energy storage inverter based on half-angle characteristics according to claim 1, characterized in that, According to PI control, the sine value of the phase angle difference is used as the input quantity to regulate the phase of the output voltage signal. The formula for PI control is: in, The phase of the output voltage. and To assign a value to a variable, The phase angles of the input voltage signal and the output voltage signal are respectively.

9. The phase synchronization method for an energy storage inverter based on half-angle characteristics according to claim 8, characterized in that, The method further includes: Input the phase of the output voltage into the PID module; The phase of the output voltage signal is controlled by the PID module to synchronize the phase of the input voltage signal and the output voltage signal.

10. The phase synchronization method for an energy storage inverter based on half-angle characteristics according to claim 1, characterized in that, After acquiring the input voltage signal of the power grid, the method further includes: Set the preset filter frequency; The input voltage signal is filtered according to the preset filtering frequency.

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