Method and device for determining null drift value, inverter and storage medium
By detecting the grid-connected/off-grid status of the inverter and calculating the average value of the electrical parameters, the zero drift value is determined, and the harm problem of the inverter output DC component to the power grid equipment is solved, and the accuracy of the zero drift value and the inverter are improved. The operation efficiency of the device.
Patent Information
- Application Number
- CN202411322550.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2025-02-18
AI Technical Summary
The inclusion of DC components in the PWM wave output by the inverter leads to zero drift value, which in turn causes harm to the power grid equipment, especially the magnetic saturation and noise vibration of the power transformer.
By detecting the grid-connected/off-grid status of the inverter, the average value of the electrical parameters of the power frequency cycle and the power grid cycle are obtained respectively, the first zero drift value and the second zero drift value are calculated, and the zero drift value is determined by the preset error judgment is determined. value.
It effectively reduces the interference of external factors on the measurement of zero drift value under different operating conditions, significantly improves the accuracy of determining zero drift value, and can accurately suppress the DC component of the inverter and improve the operating efficiency and reliability of the inverter.
Smart Images
Figure CN119471088A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of energy storage technology, and in particular to a method, apparatus, inverter, and storage medium for determining zero drift value. Background Technology
[0002] Inverters, as crucial power conversion devices in the field of power electronics, primarily function to convert DC power into AC power, and are widely used in various sectors such as industry, household use, and renewable energy systems. However, in practical applications, the inverter output voltage often contains a certain DC component. Injecting this DC component into the power grid can cause significant damage to grid equipment, primarily manifesting as a severe impact on power transformers. Power transformers are critical components in the power system; their proper operation directly affects power transmission and the quality of electricity for users. Injecting DC components into the grid causes DC bias, which is the fundamental reason affecting transformer operation. The first aspect of the harm caused by DC bias to transformers is that it leads to severe magnetic saturation of the transformer core every half-cycle, resulting in severe distortion of the excitation current, increased harmonic content, increased transformer losses, and consequently, voltage drop, preventing the power system from operating normally. Simultaneously, transformers operating in a magnetic saturation state generate significant noise and vibration. The second aspect of the harm of DC bias to transformers is that it causes severe magnetic saturation of the transformer. At this time, the magnetic flux that is normally closed in the iron core will leave the iron core, that is, the leakage flux increases, which increases the stray losses in the metal structural components of the transformer, which may lead to overheating, damage to insulation, damage to the transformer or reduce its service life.
[0003] The fundamental reason for the generation of DC component is that the PWM (Pulse Width Modulation) wave output by the inverter contains a certain DC component, which is most directly manifested as the zero drift value. Therefore, it is necessary to determine the zero drift value. Summary of the Invention
[0004] In view of the above problems, this application provides a method, apparatus, inverter and storage medium for determining zero drift value, which overcomes the above problems or at least partially solves the problem of needing to determine zero drift value.
[0005] According to one aspect of this application, a method for determining a zero drift value is provided, comprising: step S1, detecting the grid-connected / off-grid status of the inverter; if the inverter is off-grid, then proceeding to step S2; if the inverter is grid-connected, then proceeding to step S5; step S2, obtaining the average value of the electrical parameters of the inverter during the power frequency cycle to obtain a first zero drift value; step S3, determining whether the first zero drift value is within a first preset error; if so, proceeding to step S4; step S4, determining the first zero drift value as the zero drift value of the inverter when it is off-grid; step S5, obtaining the average value of the electrical parameters of the inverter during the grid cycle to obtain a second zero drift value; step S6, determining whether the second zero drift value is within a second preset error; if so, proceeding to step S7; step S7, determining the second zero drift value as the zero drift value of the inverter when it is grid-connected.
[0006] In an optional manner, the step of obtaining the average value of the electrical parameters of the inverter in the power frequency cycle to obtain the first zero drift value in step S2 includes: obtaining the average value of the electrical parameters of the inverter in multiple consecutive power frequency cycles to obtain multiple first electrical parameters, wherein the first zero drift value is the average value of the multiple first electrical parameters.
[0007] In an optional manner, step S3 further includes: if the first zero drift value is outside the first preset error, then execute step S2; accumulate the number of times step S2 is executed; determine whether the number of times step S2 is executed reaches a first preset value; if yes, then determine that the inverter is faulty; if no, then execute step S2 and step S3 until the first zero drift value is within the first preset error, and then execute step S4.
[0008] In an optional manner, the step of obtaining the average value of the electrical parameters of the inverter in the power frequency cycle to obtain the second zero drift value in step S5 includes: obtaining the average value of the electrical parameters of the inverter in multiple consecutive power grid cycles to obtain multiple second electrical parameters, wherein the second zero drift value is the average value of the multiple second electrical parameters.
[0009] In an optional manner, step S6 further includes: if the second zero drift value is outside the second preset error, then execute step S5; accumulate the number of times step S5 is executed; determine whether the number of times step S5 is executed reaches a second preset value; if yes, then determine that the inverter is faulty; if no, then execute step S5 and step S6 until the second zero drift value is within the second preset error, and then execute step S7.
[0010] In an optional embodiment, the method further includes: step S8, obtaining multiple sampled electrical parameters of the inverter's electrical parameter sampling channel when the inverter is in a shutdown state; step S9, calculating the average value of the multiple sampled electrical parameters to obtain a third zero drift value; step S10, determining whether the third zero drift value is within a third preset error, and if so, executing step S11; step S11, determining the third zero drift value as the zero drift value of the inverter shutdown.
[0011] According to one aspect of the embodiments of this application, a method for suppressing the DC component of an inverter is provided, the method comprising: step S100, determining the DC component of the inverter based on the zero drift value of the inverter, wherein the zero drift value is obtained as described in any of the preceding methods; step S200, acquiring instantaneous sampled values of the electrical parameters of the inverter; and step S300, determining the effective value of the AC quantity of the inverter based on the instantaneous sampled values and the DC component.
[0012] In an alternative approach, the formula for determining the effective value of the AC quantity of the inverter based on the instantaneous sampled value and the DC component in step S300 is as follows:
[0013]
[0014] Wherein, the R ms The effective value of the AC quantity is given by V, the instantaneous sampled value is given by A, the DC component is given by T, and the power frequency period is given by T.
[0015] According to one aspect of this application, a zero-drift value determination device is provided, comprising: a first detection module for detecting the grid-connected / off-grid status of an inverter; if the inverter is off-grid, executing a first acquisition module; if the inverter is grid-connected, executing a second acquisition module; the first acquisition module for acquiring the average value of the electrical parameters of the inverter during a power frequency cycle to obtain a first zero-drift value; a first judgment module for determining whether the first zero-drift value is within a first preset error; if so, executing a first determination module; the first determination module for determining the first zero-drift value as the zero-drift value of the inverter when it is off-grid; a second acquisition module for acquiring the average value of the electrical parameters of the inverter during a grid cycle to obtain a second zero-drift value; a second judgment module for determining whether the second zero-drift value is within a second preset error; if so, executing a second determination module; the second determination module for determining the second zero-drift value as the zero-drift value of the inverter when it is grid-connected.
[0016] According to one aspect of the embodiments of this application, an inverter is provided, the inverter comprising: at least one processor, and a memory communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the method as described above.
[0017] According to one aspect of the embodiments of this application, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the method described above.
[0018] The beneficial effects of this application include: by using the zero drift value determination method provided in this application, the zero drift value is determined by distinguishing between the grid-connected and off-grid states of the inverter and by using the average value calculation method of electrical parameters respectively. This targeted approach effectively reduces the interference of external factors on the zero drift value measurement under different operating conditions, significantly improves the accuracy of zero drift value determination, and further enables precise suppression of the DC component of the inverter based on the zero drift value.
[0019] In addition, because the grid-connected / off-grid status of the inverter is distinguished, the inverter can respond quickly to status changes, resulting in high overall operating efficiency.
[0020] Equally important, the method incorporates a preset error judgment mechanism, which can effectively filter out erroneous data that may be caused by abnormal conditions, thereby enhancing the reliability and stability of the zero drift value determination process. Attached Figure Description
[0021] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.
[0022] Figure 1 This is a schematic diagram of an application system provided in an embodiment of this application;
[0023] Figure 2 This is a schematic diagram of the hardware structure of the controller provided in an embodiment of this application;
[0024] Figure 3 This is a flowchart illustrating the method for determining the zero drift value provided in an embodiment of this application;
[0025] Figure 4 This is a schematic diagram of a sub-process of the method for determining the zero drift value provided in the embodiments of this application;
[0026] Figure 5 This is a schematic diagram of another seed process of the method for determining the zero drift value provided in the embodiments of this application;
[0027] Figure 6 This is a flowchart illustrating another method for determining zero drift value provided in an embodiment of this application;
[0028] Figure 7 This is a schematic flowchart of the inverter DC component suppression method provided in the embodiments of this application;
[0029] Figure 8 This is a schematic diagram of the zero drift value determination device provided in the embodiments of this application;
[0030] Figure 9 This is a schematic diagram of the inverter DC component suppression device provided in the embodiments of this application. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application are within the scope of protection of this application.
[0032] Furthermore, the technical features involved in the embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0033] Please see Figure 1 , Figure 1 This is a schematic diagram of an application system for an inverter provided in an embodiment of this application. The inverter is applicable to the method for determining the zero drift value, the device for determining the zero drift value, and the method for suppressing the DC component of the inverter. The application system includes an energy storage inverter system 10, which includes an inverter 100, a power source 200, a power grid 300, and a load 400.
[0034] The inverter 100 is connected to the power source 200 and the power grid 300 respectively.
[0035] The inverter 100 is used to receive the DC power input from the power source 200. The inverter 100 converts the DC power generated by the power source 200 into AC power, so that it can be connected to and meet the operating requirements of the power grid 300.
[0036] Furthermore, when the inverter 100 is connected to the power grid 300, the inverter 100 is grid-connected. In this grid-connected operation mode, the inverter 100 not only provides power to the power grid 300, but also performs power regulation and voltage support according to the needs of the power grid 300. For example, in a power grid 300 with a high proportion of power sources 200, the inverter 100 supports voltage stability of the power grid 300 by controlling the output of reactive power.
[0037] In addition, the inverter 100 optimizes power quality during the conversion process, reducing harmonic pollution and voltage fluctuations. This helps improve the overall operating efficiency and stability of the power grid 300.
[0038] Furthermore, the inverter 100, serving as the interface device between the power source 200 and the power grid 300, is of great significance for promoting the widespread application and popularization of renewable energy. It enables the power source 200 to connect to the power grid 300 more flexibly and efficiently, and to achieve bidirectional flow of electrical energy.
[0039] The power source 200 is a renewable energy utilization system, a power generation system that can convert renewable energy sources such as wind energy, hydropower and solar energy into electrical energy and input it into the inverter 100.
[0040] The power grid 300 is used to transmit and distribute electrical energy for the use of the load 400.
[0041] The load 400 can be connected to the inverter 100, the power source 200 and the power grid 300 respectively, so that the AC power output by the inverter 100 can be used by the load 400, the electrical energy generated by the power source 200 can be directly used by the load 400 (such as a DC load), and the electrical energy at the power grid 300 can also be used by the load 400 (such as an AC load).
[0042] It is understood that in some embodiments, the inverter 100 is equipped with a controller 101, which is responsible for monitoring the operating status of the inverter 100 and ensuring its safe and reliable operation. The controller 101 can actually monitor and collect the status parameters of the inverter 100 (including but not limited to AC voltage, AC current, temperature, etc.), perform necessary analysis and calculations on the relevant status parameters to obtain more status evaluation parameters, and effectively manage the inverter 100 according to specific protection and control strategies, ensuring the safe and reliable operation of the entire inverter 100. Simultaneously, the controller 101 can interact with other external devices, such as the power source 200, the power grid 300, and the load 400, through its own communication interface and analog / digital input interface to form a coordinated control, ensuring the safe, reliable, and efficient operation of the inverter 100.
[0043] The hardware structure of the controller 101 provided in the embodiments of this application will now be described.
[0044] Please see Figure 2 , Figure 2 This is a schematic diagram of the hardware structure of the controller 101 provided in this application embodiment, which can execute the method for determining the zero drift value. The controller 101 includes...
[0045] At least one processor 1011 and memory 1012 are connected in communication. Figure 2 (Taking a bus connection and a single processor as an example). Those skilled in the art will understand that... Figure 2 The structure shown is for illustrative purposes only and does not limit the structure of the inverter described above. For example, the controller 101 may also include a ratio Figure 2 The more or fewer components shown, or having the same Figure 2 The different configurations shown.
[0046] The processor 1011 is used to provide computing and control capabilities, and to control the controller 101 to execute any of the methods provided in the following embodiments, thereby managing the inverter 100 accordingly.
[0047] It is understood that the processor 1011 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.
[0048] The memory 1012, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the various calculation methods in the embodiments of this application. The processor 1011, by running the non-transitory software programs, instructions, and modules stored in the memory 1012, can implement the various calculation methods in any of the following method embodiments. The memory 1012 may include high-speed random access memory and non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 1012 may also include memories remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.
[0049] This application also provides a non-volatile computer-readable storage medium storing computer-executable instructions that are executed by an inverter using various computation methods in any of the following method embodiments.
[0050] This application provides a computer program product, including a computing program stored on a non-volatile computer-readable storage medium. The computer program includes program instructions that, when executed by a computer, cause the computer to perform various computing methods in any of the following method embodiments.
[0051] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software and a general-purpose hardware platform, or it can be implemented using hardware. Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.
[0052] Example 1
[0053] The following describes the method for determining the zero drift value provided in the embodiments of this application.
[0054] It's worth noting that even when there's no signal input to the inverter, its output will still display a small electrical parameter value. This parameter value may exist in the form of voltage or current, and we usually call it the zero-drift value. Furthermore, this zero-drift value is also considered the DC component of the inverter output.
[0055] Please see Figure 3 , Figure 3 This is a flowchart illustrating a method for determining the zero drift value provided in an embodiment of this application. The method includes the following steps:
[0056] Step S1: Detect the grid-connected / off-grid status of the inverter. If the inverter is off-grid, proceed to step S2. If the inverter is connected to the grid, proceed to step S5.
[0057] The grid-connected state of an inverter means that the inverter is connected to the power grid, while the off-grid state means that the inverter is not connected to the power grid.
[0058] There are several ways to detect the grid-connected / off-grid status of an inverter. One method is voltage and frequency detection. Specifically, the inverter's output voltage and frequency are measured and compared with the grid's rated voltage and frequency. If the inverter's output voltage and frequency match the grid (or fluctuate within acceptable limits), the inverter is considered grid-connected. If the inverter's output voltage and frequency do not match the grid, or if the output voltage and frequency cannot be detected, the inverter is considered off-grid.
[0059] Another way to detect the grid-connected / off-grid status of an inverter is through current sensing. Specifically, the inverter's output current is measured to determine if current is flowing into the grid. If current flows into the grid and its magnitude and direction meet the grid-connected requirements, the inverter is considered grid-connected; if no current flows into the grid, or if the current is abnormal, the inverter is considered off-grid.
[0060] Another way to detect the grid-connected / off-grid status of an inverter is through phase detection. Specifically, the phase difference between the inverter's output voltage and current is measured to determine whether the inverter is synchronized with the grid. If the phase difference is within the allowable range, the inverter is considered to be grid-connected; if the phase difference exceeds the allowable range, the inverter is considered to be off-grid.
[0061] Another method for detecting the grid-connected / off-grid status of an inverter is communication detection. Specifically, the grid-connected status information of the inverter is obtained through communication with the grid control system or monitoring system. If a confirmation message confirming grid connection is received, the inverter is considered to be connected to the grid; if no confirmation message is received, or if an off-grid message is received, the inverter is considered to be off-grid.
[0062] Of course, a comprehensive judgment method can also be used, that is, combining the above multiple detection methods to make a comprehensive judgment on the grid connection status of the inverter. If multiple detection methods indicate that the inverter is connected to the grid, then the inverter is confirmed to be connected to the grid; if any detection method indicates that the inverter is disconnected from the grid, then the inverter is confirmed to be disconnected from the grid, and the corresponding subsequent steps are executed.
[0063] It is worth noting that in some embodiments, if no grid connection is detected within a certain period of time (e.g., 500 milliseconds), the current state is considered to be off-grid.
[0064] Step S2: Obtain the average value of the electrical parameters of the inverter during the power frequency cycle to obtain the first zero drift value.
[0065] Among them, the electrical parameters of the inverter during the power frequency cycle include: the AC voltage or AC current during the power frequency cycle when the inverter is off-grid.
[0066] In step S2, the average value of the inverter's electrical parameters during the power frequency cycle is obtained. The power frequency cycle is one complete inverter cycle. For example, for a 50Hz power frequency inverter, the default power frequency cycle is 0.02 seconds (i.e., 20 milliseconds). This means the inverter outputs 50 complete AC cycles per second. For example, for a 60Hz power frequency inverter, the default power frequency cycle is 0.0167 seconds (i.e., 1 / 60 of a second). This means the inverter outputs 60 complete AC cycles per second.
[0067] In some embodiments, step S2 obtains the average value of the electrical parameters of the inverter during the power frequency cycle, and obtains the first zero drift value as the average value of the AC voltage or the average value of the AC current during a complete power frequency cycle.
[0068] In some embodiments, the step S2 of obtaining the average value of the electrical parameters of the inverter in a power frequency cycle to obtain the first zero drift value specifically involves: obtaining the average value of the electrical parameters of the inverter in multiple consecutive power frequency cycles to obtain multiple first electrical parameters, wherein the first zero drift value is the average value of the multiple first electrical parameters. The first electrical parameter is either the average value of the AC voltage or the average value of the AC current in a complete power frequency cycle.
[0069] In some embodiments, the average values of the electrical parameters of the inverter over 16 consecutive power frequency cycles are obtained to obtain 16 first electrical parameters, and the first zero drift value is the average value of the 16 first electrical parameters. Here, 16 is 2 to the power of 4. This setting improves data processing convenience because digital systems typically store and process data in binary form, and powers of 2 can be more easily implemented through shift operations.
[0070] Step S3: Determine whether the first zero drift value is within the first preset error. If so, proceed to step S4.
[0071] In step S3, it is determined whether the first zero drift value is within the first preset error. If so, step S4 is executed to determine the first zero drift value as the zero drift value of the inverter off-grid. If the first zero drift value is outside the first preset error, step S2 is executed, that is, the loop of re-acquiring the first zero drift value is entered, and the following steps are executed (e.g.) Figure 4 As shown):
[0072] Step S21: Accumulate the number of times step S2 has been executed.
[0073] Step S22: Determine whether the number of times step S2 has been executed has reached a first preset value. If yes, then execute step S23. If no, then execute step S2 and step S3 until the first zero drift value is within the first preset error, and then execute step S4.
[0074] The first preset value is a value set by the user, such as 16 (i.e., 2 to the power of 4), which improves the system's computational convenience.
[0075] Step S23: Determine that the inverter is faulty.
[0076] In the above process, if the first zero-drift value is not within the first preset error, step S2 will be repeated to re-obtain the first zero-drift value, and the number of times step S2 is executed will be accumulated through step S21. Step S22 is used to check whether the number of times step S2 has been executed has reached a preset limit value (first preset value). If it has, it means that in the inverter grid-connected state, the accurate first zero-drift value still cannot be obtained after multiple attempts. Therefore, it is determined that the inverter may have a fault, and step S23 is executed to handle the fault, and the inverter is not allowed to operate. If the preset value has not been reached, step S2 will continue to be executed to obtain the first zero-drift value until the first zero-drift value falls within the first preset error, and then step S4 will be executed.
[0077] Step S4: Determine the first zero drift value as the zero drift value of the inverter when it is off-grid.
[0078] Step S5: Obtain the average value of the electrical parameters of the inverter during the grid cycle to obtain the second zero drift value.
[0079] Among them, the electrical parameters of the inverter during the grid cycle include: the AC voltage or AC current of the inverter during the grid cycle when the inverter is connected to the grid.
[0080] In step S5, the average value of the electrical parameters of the inverter during the grid cycle is obtained. The grid cycle is one complete AC cycle of the inverter. In most countries, the standard power frequency of the grid is 50Hz or 60Hz, which means that the grid cycle is 0.02 seconds (i.e. 20 milliseconds) or 0.0167 seconds (i.e. 1 / 60 second).
[0081] In some embodiments, step S5 obtains the average value of the electrical parameters of the inverter in a grid cycle, and obtains the second zero drift value as the average value of the AC voltage in a complete grid cycle, or the average value of the AC current in a complete grid cycle.
[0082] In some embodiments, the step S5 of obtaining the average value of the electrical parameters of the inverter in a grid cycle to obtain the second zero-drift value specifically involves: obtaining the average value of the electrical parameters of the inverter in multiple consecutive grid cycles to obtain multiple second electrical parameters, wherein the second zero-drift value is the average value of the multiple second electrical parameters. The second electrical parameter is either the average value of the AC voltage within a complete grid cycle or the average value of the AC current within a complete grid cycle.
[0083] In some embodiments, the average values of the inverter's electrical parameters over 16 consecutive grid cycles are obtained to obtain 16 second electrical parameters, and the second zero drift value is the average of the 16 second electrical parameters. Here, 16 is 2 to the power of 4. This setting improves the convenience of data processing.
[0084] Step S6: Determine whether the second zero drift value is within the second preset error. If so, proceed to step S7.
[0085] In step S6, it is determined whether the second zero drift value is within the second preset error. If so, step S7 is executed to determine the second zero drift value as the zero drift value of the inverter off-grid. If the second zero drift value is outside the second preset error, step S5 is executed, that is, the loop of re-acquiring the second zero drift value is entered, and the following steps are executed (e.g.) Figure 5 As shown):
[0086] Step S51: Accumulate the number of times step S5 has been executed.
[0087] Step S52: Determine whether the number of times step S5 has been executed has reached the second preset value. If yes, then execute step S53. If no, then execute step S5 and step S6 until the second zero drift value is within the second preset error, and then execute step S7.
[0088] The second preset value is a value set by the user, such as 16 (i.e., 2 to the power of 4), which improves the system's computational convenience.
[0089] Step S53: Determine that the inverter is faulty.
[0090] In the above process, if the second zero-drift value is not within the second preset error, step S5 will be repeated to re-obtain the second zero-drift value, and the number of times step S5 is executed will be accumulated through step S51. Step S52 is used to check whether the number of times step S5 has been executed has reached a preset limit value (second preset value). If it has, it means that in the inverter grid-connected state, the accurate second zero-drift value still cannot be obtained after multiple attempts. Therefore, it is determined that the inverter may have a fault, and step S53 is executed to handle the fault, and the inverter is not allowed to operate. If the preset value has not been reached, step S5 will continue to be executed to obtain the second zero-drift value until the second zero-drift value falls within the second preset error, and then step S7 will be executed.
[0091] It is worth noting that the second preset error can have the same value as the first preset error.
[0092] Step S7: Determine the second zero drift value as the zero drift value for grid connection of the inverter.
[0093] In this embodiment of the application, the method for determining the zero drift value includes: Step S1, detecting the grid-connected / off-grid status of the inverter; if the inverter is off-grid, then proceed to Step S2; if the inverter is connected to the grid, then proceed to Step S5; Step S2, obtaining the average value of the electrical parameters of the inverter during the power frequency cycle to obtain a first zero drift value; Step S3, determining whether the first zero drift value is within a first preset error; if so, proceed to Step S4; Step S4, determining the first zero drift value as the zero drift value of the inverter when it is off-grid; Step S5, obtaining the average value of the electrical parameters of the inverter during the grid cycle to obtain a second zero drift value; Step S6, determining whether the second zero drift value is within a second preset error; if so, proceed to Step S7; Step S7, determining the second zero drift value as the zero drift value of the inverter when it is connected to the grid. The zero-drift value determination method provided in this application distinguishes between the grid-connected and off-grid states of the inverter and determines the zero-drift value by calculating the average value of electrical parameters for each state. This targeted approach effectively reduces the interference of external factors on the zero-drift value measurement under different operating conditions, significantly improving the accuracy of the zero-drift value determination. Furthermore, the DC component of the inverter can be precisely suppressed based on this zero-drift value. In addition, because the grid-connected / off-grid states of the inverter are distinguished, the inverter can respond quickly to state changes, resulting in high overall operating efficiency. Equally important, the method introduces a preset error judgment mechanism, which can effectively filter out erroneous data that may be caused by abnormal conditions, enhancing the reliability and stability of the zero-drift value determination process.
[0094] Example 2
[0095] The following describes another method for determining the zero drift value provided in the embodiments of this application. Please refer to... Figure 6 , Figure 6 This is a flowchart illustrating another method for determining the zero drift value provided in this application embodiment. In addition to steps S1 to S7 described above, this method also includes the following steps:
[0096] Step S8: When the inverter is in a shutdown state, obtain multiple sampled electrical parameters of the inverter's electrical parameter sampling channel.
[0097] The inverter's electrical parameter sampling channels include a voltage sampling channel and a current sampling channel.
[0098] The voltage sampling channel is sampled to obtain multiple sampled voltages; the current sampling channel is sampled to obtain multiple sampled currents.
[0099] It is worth noting that in some embodiments, the values of multiple sampled electrical parameters are 8192 (2 to the power of 13), which not only obtains more sampled data, improving the accuracy of subsequent steps, but also enhances the convenience of system calculation.
[0100] Step S9: Calculate the average value of the multiple sampled electrical parameters to obtain the third zero drift value.
[0101] Step S10: Determine whether the third zero drift value is within the third preset error. If so, proceed to step S11.
[0102] In step S10, it is determined whether the third zero drift value is within the third preset error. If so, step S11 is executed to determine the third zero drift value as the zero drift value for inverter shutdown. If the third zero drift value is outside the third preset error, step S8 is executed, that is, the loop of re-acquiring the third zero drift value is entered, and then step S9 is executed.
[0103] Step S11: Determine the third zero-drift value as the zero-drift value for inverter shutdown.
[0104] In this embodiment, the method for determining the zero drift value further includes step S8, obtaining multiple sampled electrical parameters of the inverter's electrical parameter sampling channel when the inverter is in a shutdown state; step S9, calculating the average value of the multiple sampled electrical parameters to obtain a third zero drift value; step S10, determining whether the third zero drift value is within a third preset error; if so, proceeding to step S11; step S11, determining the third zero drift value as the zero drift value of the inverter when it is shut down. This method can obtain the zero drift value when the inverter is shut down. By distinguishing between the grid-connected and off-grid states of the inverter and the shutdown state of the inverter, and using the calculation method of the average value of electrical parameters respectively, the zero drift value is determined. This targeted approach further effectively reduces the interference of external factors on the zero drift value measurement under different operating states, significantly improving the accuracy of the zero drift value determination. Furthermore, the DC component of the inverter can be precisely suppressed based on this zero drift value. Furthermore, by distinguishing between the inverter's grid-connected / off-grid status and its shutdown status, the inverter can respond quickly to status changes, resulting in high overall operating efficiency. Equally important, the method incorporates a preset error judgment mechanism, which effectively filters out erroneous data that may be caused by abnormal conditions, further enhancing the reliability and stability of the zero-drift value determination process.
[0105] Example 3
[0106] The following describes the inverter DC component suppression method provided in the embodiments of this application. After the process of Embodiment 1 or Embodiment 2 is completed, the task of calculating the zero drift value is terminated, and the inverter DC component suppression process begins. Please refer to [link to relevant documentation]. Figure 7 , Figure 7 This is a flowchart illustrating a method for suppressing the DC component of an inverter according to an embodiment of this application. The method includes the following steps:
[0107] Step S100: Determine the DC component of the inverter based on the zero drift value of the inverter, wherein the zero drift value is obtained by the method described in either Embodiment 1 or Embodiment 2.
[0108] The aforementioned DC component is the zero drift value obtained by the method described in either Example 1 or Example 2. It can be the zero drift value when the inverter is off-grid, the zero drift value when the inverter is on-grid, or the zero drift value when the inverter is off-grid.
[0109] Step S200: Obtain the instantaneous sampled values of the electrical parameters of the inverter.
[0110] The instantaneous sampled value is the current or voltage value at the inverter output terminal at a specific moment. That is, it is the sampled data at the inverter output terminal when a DC input signal is present.
[0111] Step S300: Determine the effective value of the AC quantity of the inverter based on the instantaneous sampled value and the DC component.
[0112] In some embodiments, the formula for determining the effective value of the AC quantity of the inverter based on the instantaneous sampled value and the DC component in step S300 is:
[0113]
[0114] Wherein, the R ms The effective value of the AC quantity is given by V, the instantaneous sampled value is given by A, the DC component is given by T, and the power frequency period is given by T.
[0115] In the formula, VA, which stands for instantaneous sampled value minus zero drift, is used to remove the influence of the DC component on the calculation of the effective value of the AC quantity. By using this formula, the effective value of the AC quantity of the inverter is obtained after removing the DC component, thus achieving the suppression of the DC component.
[0116] In this embodiment, the method for suppressing the DC component of an inverter includes step S100, determining the DC component of the inverter based on the zero-drift value of the inverter, wherein the zero-drift value is obtained as described in either Embodiment 1 or Embodiment 2; step S200, acquiring instantaneous sampled values of the electrical parameters of the inverter; and step S300, determining the effective value of the AC quantity of the inverter based on the instantaneous sampled values and the DC component. Through this method, by determining the DC component using Embodiment 1 or Embodiment 2, and by acquiring instantaneous sampled values of the electrical parameters of the inverter in real time and accurately calculating the effective value of the AC quantity, the DC component is suppressed, thereby achieving effective optimization and improvement of the inverter output.
[0117] Example 4
[0118] The following describes the zero drift value determination device provided in the embodiments of this application. Please refer to [link to relevant documentation]. Figure 8 , Figure 8This is a schematic diagram of a zero-drift value determination device provided in an embodiment of this application. The zero-drift value determination device 1 includes a first detection module 11, used to detect the grid-connected / off-grid status of the inverter. If the inverter is off-grid, a first acquisition module 12 is executed; if the inverter is connected to the grid, a second acquisition module 15 is executed. The first acquisition module 12 is used to acquire the average value of the electrical parameters of the inverter during the power frequency cycle to obtain a first zero-drift value. The first judgment module 13 is used to determine whether the first zero-drift value is within a first preset error. If so, a first determination module 14 is executed. The first determination module 14 is used to determine the first zero-drift value as the zero-drift value of the inverter when it is off-grid. The second acquisition module 15 is used to acquire the average value of the electrical parameters of the inverter during the grid cycle to obtain a second zero-drift value. The second judgment module 16 is used to determine whether the second zero-drift value is within a second preset error. If so, a second determination module 17 is executed. The second determination module 17 is used to determine the second zero-drift value as the zero-drift value of the inverter when it is connected to the grid.
[0119] In some embodiments, the first acquisition module 12 is specifically used to acquire the average value of the electrical parameters of the inverter in a series of consecutive power frequency cycles to obtain a plurality of first electrical parameters, wherein the first zero drift value is the average value of the plurality of first electrical parameters.
[0120] In some embodiments, the first judgment module 13 is further configured to: if the first zero drift value is outside the first preset error, then the first acquisition module 12; and accumulate the number of times the first acquisition module 12 is executed; determine whether the number of times the first acquisition module 12 is executed reaches a first preset value; if yes, then determine that the inverter is faulty; if no, then execute the first acquisition module 12 and the first judgment module 13 until the first zero drift value is within the first preset error, and execute the first determination module 14.
[0121] In some embodiments, the second acquisition module 15 is specifically used to acquire the average value of the electrical parameters of the inverter in a series of grid cycles to obtain a plurality of second electrical parameters, wherein the second zero drift value is the average value of the plurality of second electrical parameters.
[0122] In some embodiments, the second judgment module 16 is further configured to execute the second acquisition module 15 if the second zero drift value is outside the second preset error; and to accumulate the number of times the second acquisition module 15 is executed; to determine whether the number of times the second acquisition module 15 is executed reaches a second preset value; if yes, to determine that the inverter is faulty; if no, to execute the second acquisition module 15 and the second judgment module 16 until the second zero drift value is within the second preset error, and to execute the second determination module 17.
[0123] In some embodiments, the zero drift value determination device 1 further includes: a third acquisition module 18, used to acquire multiple sampled electrical parameters of the electrical parameter sampling channel of the inverter when the inverter is in a shutdown state; an averaging module 19, used to calculate the average value of the multiple sampled electrical parameters to obtain a third zero drift value; a third judgment module 20, used to determine whether the third zero drift value is within a third preset error, and if so, to execute the third determination module 21; the third determination module 21 is used to determine the third zero drift value as the zero drift value of the inverter shutdown.
[0124] In this embodiment, the grid-connected / off-grid status of the inverter is detected by the first detection module 11. If the inverter is off-grid, the first acquisition module 12 is executed; if the inverter is connected to the grid, the second acquisition module 15 is executed. The first acquisition module 12 acquires the average value of the electrical parameters of the inverter during the power frequency cycle to obtain the first zero drift value. The first judgment module 13 determines whether the first zero drift value is within a first preset error. If so, the first determination module 14 is executed. The first determination module 14 determines the first zero drift value as the zero drift value of the inverter when it is off-grid. The second acquisition module 15 acquires the value of the inverter during the grid cycle. The average value of the electrical parameters is used to obtain the second zero-drift value. The second judgment module 16 determines whether the second zero-drift value is within the second preset error. If so, the second determination module 17 is executed. The second determination module 17 determines the second zero-drift value as the grid-connected zero-drift value of the inverter. By distinguishing between the grid-connected and off-grid states of the inverter, the zero-drift value is determined using the average value calculation method of the electrical parameters. This targeted approach effectively reduces the interference of external factors on the zero-drift value measurement under different operating states, significantly improving the accuracy of the zero-drift value determination. Furthermore, the DC component of the inverter can be precisely suppressed based on this zero-drift value. In addition, because the grid-connected / off-grid states of the inverter are distinguished, the inverter can quickly respond to state changes, resulting in high overall inverter operating efficiency. Equally important, the method introduces a preset error judgment mechanism, which can effectively filter out erroneous data that may be caused by abnormal conditions, enhancing the reliability and stability of the zero-drift value determination process.
[0125] Example 5
[0126] The following section discusses the inverter DC component suppression device provided in the embodiments of this application. Please refer to [link to relevant documentation]. Figure 9 , Figure 9This is a schematic diagram of an inverter DC component suppression device provided in an embodiment of this application. The inverter DC component suppression device 3 includes a determination module 31, used to determine the DC component of the inverter based on the zero drift value of the inverter, wherein the zero drift value is obtained according to the zero drift value determination device 1 provided in Embodiment 4; an acquisition module 32, used to acquire the instantaneous sampled value of the electrical parameters of the inverter; and a suppression module 33, used to determine the effective value of the AC quantity of the inverter based on the instantaneous sampled value and the DC component.
[0127] In this embodiment, the determining module 31 determines the DC component of the inverter based on the zero drift value of the inverter, which is obtained by the zero drift value determining device 1 provided in Embodiment 4; the acquiring module 32 acquires the instantaneous sampled values of the inverter's electrical parameters; and the suppressing module 33 determines the effective value of the inverter's AC quantity based on the instantaneous sampled values and the DC component. Thus, by determining the DC component through the zero drift value determining device 1 and by acquiring the instantaneous sampled values of the inverter's electrical parameters in real time and accurately calculating the effective value of the AC quantity, the suppression of the DC component is achieved, thereby enabling effective optimization and improvement of the inverter output.
[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above. For the sake of brevity, they are not provided in detail; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. A method for determining a zero drift value, characterized in that: The method comprises: Step S1, detecting the grid-connected / off-grid state of the inverter, if the inverter is off-grid, executing step S2, if the inverter is grid-connected, executing step S5; Step S2, obtaining an average value of an electrical parameter of the inverter in a power frequency cycle to obtain a first zero drift value; Step S3, determining whether the first zero drift value is within a first preset error, if so, executing step S4; Step S4, determining the first zero drift value as the zero drift value of the inverter when it is off-grid; Step S5, obtaining an average value of an electrical parameter of the inverter during a power grid cycle to obtain a second zero drift value; Step S6, determining whether the second zero drift value is within a second preset error, if so, executing step S7; Step S7: determine the second zero drift value as the zero drift value of the inverter connected to the grid.
2. The method according to claim 1, characterized in that The step of obtaining the average value of the electrical parameters of the inverter in the power frequency cycle to obtain the first zero drift value in step S2 includes: The average values of the electrical parameters of the inverter in a plurality of consecutive power frequency cycles are respectively obtained to obtain a plurality of first electrical parameters, wherein the first zero drift value is the average value of the plurality of first electrical parameters.
3. The method according to claim 2, characterized in that Step S3 further includes: if the first zero drift value is outside the first preset error, executing step S2; Accumulating the number of executions of step S2; Determine whether the execution times of step S2 reaches a first preset value; If yes, it is determined that the inverter is faulty; If not, the step S2 and the step S3 are executed until the first zero drift value is within the first preset error, and the step S4 is executed.
4. The method according to claim 1, characterized in that: The step of obtaining the average value of the electrical parameters of the inverter in the power frequency cycle to obtain the second zero drift value in step S5 includes: The average values of the electrical parameters of the inverter in a plurality of consecutive grid cycles are respectively obtained to obtain a plurality of second electrical parameters, and the second zero drift value is the average value of the plurality of second electrical parameters.
5. The method according to claim 4, characterized in that Step S6 also includes: if the second zero drift value is outside the second preset error, executing step S5; Accumulating the number of executions of step S5; Determine whether the execution times of step S5 reaches a second preset value; If yes, it is determined that the inverter is faulty; If not, the step S5 and the step S6 are executed until the second zero drift value is within the second preset error, and the step S7 is executed.
6. The method according to any one of claims 1 to 5, characterized in that: The method further comprises: Step S8, when the inverter is in shutdown state, obtaining a plurality of sampled electrical parameters of an electrical parameter sampling channel of the inverter; Step S9, calculating an average value of a plurality of the sampled electrical parameters to obtain a third zero drift value; Step S10, determining whether the third zero drift value is within a third preset error, if so, executing step S11; Step S11: determining the third zero drift value as the zero drift value for shutting down the inverter.
7. A method for suppressing a DC component of an inverter, characterized in that: The method comprises: Step S100, determining a DC component of the inverter according to a zero drift value of the inverter, wherein the zero drift value is obtained according to the method described in any one of claims 1 to 6; Step S200, obtaining instantaneous sampling values of electrical parameters of the inverter; Step S300, determining the effective value of the alternating current quantity of the inverter according to the instantaneous sampling value and the direct current component.
8. The method according to claim 7, characterized in that The formula for determining the effective value of the AC quantity of the inverter according to the instantaneous sampling value and the DC component in step S300 is: Among them, the R ms is the effective value of the AC quantity, V is the instantaneous sampling value, A is the DC component, and T is the power frequency period.
9. A device for determining a zero drift value, characterized in that: The device comprises: A first detection module is used to detect the grid-connected / off-grid state of the inverter. If the inverter is off-grid, the first acquisition module is executed; if the inverter is grid-connected, the second acquisition module is executed; A first acquisition module, used to acquire an average value of an electrical parameter of the inverter in a power frequency period to obtain a first zero drift value; A first judging module, configured to judge whether the first zero drift value is within a first preset error, and if so, execute a first determining module; A first determining module, configured to determine the first zero drift value as a zero drift value of the inverter being off-grid; A second acquisition module is used to acquire an average value of an electrical parameter of the inverter during a power grid cycle to obtain a second zero drift value; A second judging module, configured to judge whether the second zero drift value is within a second preset error, and if so, execute a second determining module; The second determining module is used to determine the second zero drift value as the zero drift value of the inverter connected to the grid.
10. An inverter, characterized in that: include: at least one processor; as well as A memory, wherein the memory is communicatively connected to the at least one processor, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method according to any one of claims 1 to 8.
11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of the method according to any one of claims 1 to 8.