Function verification method, device and electronic equipment

Abstract

The present invention provides a function verification method, device and electronic device. In the present invention, when the grid-connected parameters of the power grid simulator are adjusted to meet the function verification triggering conditions, it is determined whether the output power of the inverter is within the specified power range. If so, the output parameters of the AC side of the inverter are obtained, and based on the output parameters, the grid-off time point that meets the set current rule is determined, and whether the grid-off time meets the grid-off time rule is determined, and the function verification result is determined based on the determination result; the grid-off time is determined based on the time point of adjusting the grid-connected parameters of the power grid simulator and the grid-off time point. That is, in the present invention, the over-voltage / under-frequency protection function can be automatically verified, and the verification is based on the output parameters of the AC side of the inverter, which can improve accuracy and efficiency compared with the manual function verification method.

Description

Technical Field

[0001] The present invention relates to the field of data processing, and more specifically, to a function verification method, device and electronic equipment. Background Art

[0002] The over-voltage / under-frequency protection function is to prevent the voltage or frequency at the connection point between the inverter and the connected distribution network from exceeding the normal operating range. The grid connection standards for new energy sources such as photovoltaic and wind power stipulate that when the inverter detects that the voltage / frequency at the grid connection point exceeds or falls below the normal operating range, it can be disconnected from the grid within the specified time to avoid damage.

[0003] After the inverter leaves the factory, the inverter's overvoltage / underfrequency protection function needs to be verified to determine whether the function can work properly. Currently, when performing function verification, manual visual verification is performed manually, which has low accuracy and low efficiency. Summary of the invention

[0004] In view of this, the present invention provides a function verification method, device and electronic equipment to solve the problem of low accuracy and low efficiency in manually visually verifying the over-voltage / under-frequency protection function of the inverter.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A function verification method is applied to a controller, and the function verification method comprises:

[0007] When the grid-connected parameters of the power grid simulator are adjusted to meet the function verification triggering conditions, determining whether the output power of the inverter is within the specified power range;

[0008] If so, obtaining the output parameters of the inverter AC side, and determining the off-grid time point that satisfies the set current rule based on the output parameters;

[0009] Determine whether the off-grid time satisfies the off-grid time rule, and determine the function verification result based on the determination result; the off-grid time is determined based on the time point of adjusting the grid connection parameters of the power grid simulator and the off-grid time point.

[0010] Optionally, obtaining an output parameter of the AC side of the inverter includes:

[0011] The output parameters after the specified time point before the grid connection parameters of the power grid simulator are adjusted and satisfy the specified data volume display rules are obtained.

[0012] Optionally, based on the output parameter, determining a grid-off time point that satisfies a set current rule includes:

[0013] Acquire a current value of a first sampling point in the output parameter, and a current value of a second sampling point located a specified number of times after the first sampling point;

[0014] Determine whether all the acquired current values ​​meet the preset current rules;

[0015] If so, the time point corresponding to the first sampling point that earliest meets the preset current rule is used as the off-grid time point.

[0016] Optionally, obtaining current values ​​of second sampling points located a specified number of times after the first sampling point includes:

[0017] Current values ​​of second sampling points, which are a first specified number and are located after the first sampling point, are acquired within a specified current cycle.

[0018] Optionally, obtaining current values ​​of a first specified number of second sampling points within a specified current cycle after the first sampling point includes:

[0019] Acquire current values ​​of second sampling points, which are a first specified number and uniformly distributed within a first current cycle after the first sampling point;

[0020] or,

[0021] Current values ​​of second sampling points, which are a first specified number and unevenly distributed, are acquired within a first current cycle after the first sampling point.

[0022] Optionally, determining whether all the acquired current values ​​satisfy a preset current rule includes:

[0023] Determine whether all the acquired current values ​​are less than a preset current threshold;

[0024] The preset current threshold is a preset current value, or a maximum absolute current value of the output parameters of the AC side of the inverter within a third specified time range after the grid connection parameters of the power grid simulator are adjusted.

[0025] Optionally, taking the time point corresponding to the first sampling point that earliest satisfies the preset current rule as the off-grid time point includes:

[0026] The time point corresponding to the first sampling point that earliest meets the preset current rule is used as the initial off-grid time point;

[0027] The initial offline time point is verified, and after the verification passes, the initial offline time point is used as the offline time point.

[0028] Optionally, verifying the initial offline time point includes:

[0029] Acquire a second specified number of third sampling points that are consecutive after the first sampling point corresponding to the initial offline time point;

[0030] Determine whether the current values ​​of the first sampling point corresponding to the initial off-grid time point and all the third sampling points meet the set current relationship rule;

[0031] If so, it is determined that the initial offline time point check has passed.

[0032] Optionally, determining whether the current values ​​of the first sampling point corresponding to the initial off-grid time point and all the third sampling points satisfy a set current relationship rule includes:

[0033] Calculate the root mean square value and the average value of the absolute value of the current value at the first sampling point corresponding to the initial off-grid time point and all the third sampling points;

[0034] It is determined whether a ratio of the root mean square value to the average value is greater than a preset ratio threshold.

[0035] Optionally, determining whether the offline time satisfies an offline time rule, and determining a function verification result based on the determination result includes:

[0036] Determine whether the offline time is less than a preset offline time threshold, and obtain a determination result;

[0037] In the case where the determination result is less than, the function verification result is determined to be a parameter indicating that the verification has passed.

[0038] Optionally, after determining the function verification result based on the determination result, the method further includes:

[0039] An amplification instruction including the off-grid time point is sent to the oscilloscope, so that the oscilloscope responds to the amplification instruction, amplifies and captures the current waveform including the off-grid time point, and uploads the captured image to the controller.

[0040] Optionally, when it is determined that the output power of the inverter is not within the specified power range, the method further includes:

[0041] The functional verification result is determined to be a parameter that characterizes the failure of the verification.

[0042] A function verification device is applied to a controller, and the function verification device comprises:

[0043] A power determination module is used to determine whether the output power of the inverter is within a specified power range when the grid connection parameters of the power grid simulator are adjusted to meet the function verification triggering conditions;

[0044] A time point determination module, for obtaining the output parameters of the AC side of the inverter, and determining the off-grid time point that satisfies the set current rule based on the output parameters;

[0045] The function verification module is used to determine whether the off-grid time meets the off-grid time rule, and determine the function verification result based on the determination result; the off-grid time is determined based on the time point of adjusting the grid connection parameters of the power grid simulator and the off-grid time point.

[0046] A controller is used to execute the above function verification method.

[0047] A function verification system comprises an inverter and the above-mentioned controller; the inverter is connected to the controller.

[0048] Optionally, it also includes:

[0049] Power analyzer and oscilloscope;

[0050] The power analyzer and the oscilloscope are connected to the controller and the inverter respectively;

[0051] The power analyzer is used to collect the output power of the inverter and send it to the controller;

[0052] The oscilloscope is used to collect the output parameters of the inverter and send them to the controller, receive the amplification instruction including the off-grid time point sent by the controller, respond to the amplification instruction, amplify and capture the current waveform including the off-grid time point, and upload the captured image to the controller.

[0053] Optionally, it also includes:

[0054] A photovoltaic simulation power supply and a power grid simulator, wherein the photovoltaic simulation power supply and the power grid simulator are respectively connected to the controller; the photovoltaic simulation power supply is connected to the DC side of the inverter, and the power grid simulator is connected to the AC side of the inverter.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The present invention provides a function verification method, device and electronic device. In the present invention, when the grid-connected parameters of the power grid simulator are adjusted to meet the function verification triggering conditions, it is determined whether the output power of the inverter is within the specified power range. If so, the output parameters of the AC side of the inverter are obtained, and based on the output parameters, the grid-off time point that meets the set current rule is determined, and whether the grid-off time meets the grid-off time rule is determined, and the function verification result is determined based on the determination result; the grid-off time is determined based on the time point of adjusting the grid-connected parameters of the power grid simulator and the grid-off time point. That is, in the present invention, the over-voltage / under-frequency protection function can be automatically verified, and the verification is based on the output parameters of the AC side of the inverter, which can improve accuracy and efficiency compared with the manual function verification method. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0058] Figure 1 A schematic diagram of the structure of a function verification system provided by an embodiment of the present invention;

[0059] Figure 2 A method flow chart of a function verification method provided by an embodiment of the present invention;

[0060] Figure 3 A method flow chart of another function verification method provided by an embodiment of the present invention;

[0061] Figure 4 A method flow chart of another function verification method provided by an embodiment of the present invention;

[0062] Figure 5 A schematic diagram of a scenario of a waveform diagram provided by an embodiment of the present invention;

[0063] Figure 6 A schematic diagram of another scenario of a waveform diagram provided by an embodiment of the present invention;

[0064] Figure 7 A schematic diagram of a scenario of another waveform diagram provided by an embodiment of the present invention;

[0065] Figure 8 A schematic diagram of the structure of a function verification device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] In order for those skilled in the art to have some understanding of the professional terms in this scheme, the professional terms in this scheme are now introduced.

[0068] Inverters, such as photovoltaic inverters, are devices that convert the variable DC voltage generated by photovoltaic (PV) solar panels into mains frequency alternating current (AC), which can be fed back into the commercial transmission system or used by off-grid power grids.

[0069] Over-voltage / under-frequency protection function: In order to prevent the voltage or frequency at the connection point between the inverter and the connected distribution network from exceeding the normal operating range, such high voltage, low voltage, high frequency, and low frequency may cause damage to the equipment connected to the distribution network and the distribution network itself. Therefore, the photovoltaic grid-connected standard stipulates that when the inverter detects that the voltage / frequency at the grid-connected point exceeds or is lower than the normal operating range, it can be disconnected from the grid within the specified time to avoid damage.

[0070] In actual applications, the inverter's over-voltage / under-frequency protection function not only involves the safety of the equipment itself, but also endangers the entire distribution network if the protection is improper. Therefore, it is necessary to test whether the inverter's over-voltage / under-frequency protection function can meet the requirements of standards in different countries and regions. When testing the over-voltage / under-frequency protection function, the main purpose is to test whether the inverter can be disconnected from the grid when over-voltage / under-frequency occurs, and if it can be disconnected, whether the disconnection time meets the requirements.

[0071] At present, the solutions adopted in the test process are all manual methods. Specifically, an oscilloscope is used to monitor the current / voltage on the AC side of the inverter. After manually changing the grid connection point voltage to trigger the inverter's over-voltage / under-frequency protection function, the oscilloscope is manually operated to pause, amplify the current waveform, analyze the current waveform to calculate the off-grid time, and save the data to a storage medium, such as a USB flash drive.

[0072] This method not only requires repeated and frequent operation of different devices to complete the test, but also the operator needs to maintain a high degree of concentration during the entire test process to capture and analyze the oscilloscope waveform. The entire process is prone to inattention leading to repeated testing and a large amount of human interference. The operation is complicated, and the data results are highly volatile and inconsistent during multiple tests, resulting in low accuracy and efficiency.

[0073] In order to solve the problems of complex operation, easy repeated testing, long time consumption, low accuracy, etc., this method adopts a centralized controller to uniformly operate the relevant equipment and automatically capture and analyze the data. It not only realizes the automatic execution of the entire test process, but also can accurately analyze the data, which can improve the accuracy of data processing and improve efficiency.

[0074] Specifically, the present invention provides a function verification method, device and electronic device. In the present invention, when the grid-connected parameters of the power grid simulator are adjusted to meet the function verification triggering conditions, it is determined whether the output power of the inverter is within the specified power range. If so, the output parameters of the AC side of the inverter are obtained, and based on the output parameters, the grid-off time point that meets the set current rule is determined, and whether the grid-off time meets the grid-off time rule is determined, and the function verification result is determined based on the determination result; the grid-off time is determined based on the time point of adjusting the grid-connected parameters of the power grid simulator and the grid-off time point. That is, in the present invention, the over-voltage / under-frequency protection function can be automatically verified, and the verification is based on the output parameters of the AC side of the inverter, which can improve accuracy and efficiency compared with the manual function verification method.

[0075] In order to enable those skilled in the art to more clearly understand the overall implementation process of the present invention, the specific hardware architecture of the present invention, namely the function verification system, is now introduced. It should be noted that the inverter in this embodiment can be a photovoltaic inverter, and can also be an inverter connected to a wind turbine. This embodiment takes a photovoltaic inverter as an example for illustration, and other types of inverters are similar. Figure 1 , the functional verification system includes:

[0076] Photovoltaic simulation power supply, photovoltaic inverter, power grid simulator, power analyzer, oscilloscope and controller. The photovoltaic simulation power supply, photovoltaic inverter, power grid simulator, power analyzer and oscilloscope are connected to the controller respectively.

[0077] The output end of the photovoltaic simulation power supply is connected to the DC side of the photovoltaic inverter, and the AC side of the photovoltaic inverter is connected to the output end of the power grid simulator.

[0078] The power analyzer and the oscilloscope are connected to the controller and the photovoltaic inverter respectively.

[0079] Photovoltaic simulation power supply simulates the battery cell and provides energy at the input end;

[0080] The grid simulator is configured with appropriate voltage / frequency to facilitate simulation of PV inverters connected to the distribution network.

[0081] The power analyzer is used to read the voltage, current, power and other information on the AC side of the photovoltaic inverter.

[0082] The oscilloscope is used to read the waveform and data of the voltage and current corresponding to the AC side of the photovoltaic inverter.

[0083] The controller is connected to the above-mentioned devices through RS232, RS485, GPIB, USB, ETHernet serial ports or buses, and realizes parameter configuration, related actions and reading related data of each device during the test through standard SCPI commands or calling dynamic libraries. If the read data needs to be processed, the data will be passed to the controller's internal computing unit or external computing unit for processing, and the processing results will be returned to the controller for display, storage and upload to the background or other platforms.

[0084] When checking the overvoltage / underfrequency protection function, first follow Figure 1 Connect the devices and make them operate normally. At this time, the inverter is connected to the grid and operates.

[0085] When the function check starts, the controller sends a grid-connected parameter adjustment instruction to the grid simulator, so that the grid simulator changes its own grid-connected parameters, such as voltage and / or frequency.

[0086] When adjusting the grid-connected parameters, it is necessary to adjust the grid-connected parameters to a data range that can trigger the over-voltage / under-frequency protection function of the photovoltaic inverter, so that the photovoltaic inverter can be triggered to go off-grid.

[0087] Based on the above content, another embodiment of the present invention provides a function verification method, which is mainly used to verify the over-voltage / under-frequency protection function of the inverter. When performing the over-voltage / under-frequency protection function test, it is mainly used to test whether the inverter can be disconnected from the grid when it is over-voltage / under-frequency, and whether the disconnection time meets the requirements when it can be disconnected from the grid. Applied to the above controller, refer to Figure 2 , the function verification method comprises:

[0088] S11. Determine whether the output power of the inverter is within a specified power range; if so, execute step S12.

[0089] Specifically, when the grid-connected parameters of the power grid simulator are adjusted to meet the function verification trigger conditions, it is determined whether the output power of the inverter, such as the photovoltaic inverter, is within the specified power range. Before adjusting the grid-connected parameters of the power grid simulator to meet the function verification trigger conditions, it is necessary to synchronize the acquisition time of the collected grid-connected parameters of the power grid simulator and the output parameters (current, voltage, etc.) of the photovoltaic inverter to avoid the problem of inaccurate determination of the off-grid time point caused by time asynchrony.

[0090] In this embodiment, adjusting the grid-connected parameters of the grid simulator to meet the function verification trigger condition is to adjust the grid-connected parameters to a data range that can trigger the over-voltage / under-frequency protection function of the photovoltaic inverter, triggering the photovoltaic inverter to go off-grid. At this point, it is considered that adjusting the grid-connected parameters of the grid simulator meets the function verification trigger condition.

[0091] Thereafter, the data collected by the power analyzer is used to determine whether the output power of the PV inverter is within the specified power range.

[0092] The specified power range is a power range of the photovoltaic inverter when it is off-grid. When the photovoltaic inverter is working normally, the power range is greater than the power range when it is off-grid. Therefore, it is possible to determine whether the photovoltaic inverter is off-grid by the output power of the photovoltaic inverter.

[0093] If the output power of the photovoltaic inverter is within the specified power range, it means that the grid-off is successful, and then continue to determine whether the grid-off time of the photovoltaic inverter meets the requirements.

[0094] If the output power of the PV inverter is not within the specified power range, it means that the disconnection from the grid is unsuccessful. At this time, the function verification result is determined to be a parameter representing that the verification failed, such as text representing that the verification failed or an icon representing that the verification failed, such as 111, and then the function verification result is output and displayed.

[0095] S12: Obtain output parameters of the inverter AC side, and determine a grid-off time point that satisfies a set current rule based on the output parameters.

[0096] In this embodiment, the output parameters of the inverter, such as the AC side of the photovoltaic inverter, are the waveforms and data of the voltage and current collected by the oscilloscope. When collecting the output parameters, in order to avoid interference, the collected output parameters can be filtered.

[0097] When specifically acquiring the output parameters of the AC side of the photovoltaic inverter, the output parameters that meet the specified data volume display rules and are after a specified time point before adjusting the grid-connected parameters of the power grid simulator may be acquired.

[0098] In this embodiment, the output parameters obtained will include some data before the grid-connected parameters of the power grid simulator are adjusted. This is because the time point of adjusting the grid-connected parameters of the power grid simulator may not be a complete sampling point moment. Therefore, in order to ensure the integrity of the data, that is, including all data after the time point of adjusting the grid-connected parameters of the power grid simulator, in this embodiment, the data will be obtained in advance. When acquiring, in order to ensure that there is enough data in the subsequent data analysis, in this embodiment, if the data at the time point of adjusting the grid-connected parameters of the power grid simulator is located in the middle left position of the oscilloscope display interface, it is considered that the data volume is sufficient.

[0099] In the above embodiment, whether the data volume is sufficient is determined by the display position of the data on the display interface. In addition, whether the data volume of the collected output parameters is sufficient can also be determined. If the collected data volume is greater than the set data volume threshold, it is considered that the data volume requirement is met.

[0100] After the output parameters of the AC side of the photovoltaic inverter are obtained, a grid-off time point that satisfies a set current rule is determined based on the output parameters.

[0101] Among them, the off-grid time point is the time point when the photovoltaic inverter is successfully off-grid.

[0102] S13: Determine whether the offline time satisfies the offline time rule, and determine the function verification result based on the determination result.

[0103] The off-grid time is determined based on the time point of adjusting the grid connection parameters of the power grid simulator and the off-grid time point.

[0104] Specifically, the difference between the time point of adjusting the grid connection parameters of the grid simulator and the grid disconnection time point is used as the grid disconnection time. The grid disconnection time here refers to the time required for an inverter, such as a photovoltaic inverter, to disconnect from the grid.

[0105] Then, it is determined whether the off-line time is less than a preset off-line time threshold to obtain a determination result. When the determination result is less than, the function verification result is determined to be a parameter indicating that the verification has passed.

[0106] After the function verification result is determined based on the determination result, it is necessary to save the waveform of the oscilloscope at the time of disconnection. At this time, an amplification instruction including the time point of disconnection is sent to the oscilloscope.

[0107] The oscilloscope responds to the amplification instruction, amplifies the current waveform including the off-grid time point, and performs an image screenshot operation. When taking a screenshot, a waveform within a period of time including the off-grid time point, such as within 2ms, can be captured. The captured image is then uploaded to the controller. The controller stores the above screenshots, data during the verification process, and original data (such as the above output parameters, etc.) in a database, and performs an upload operation if there is a need to upload data. In addition, if there is a need to generate a report, the above screenshots, data during the verification process, and original data can be made into report content and output.

[0108] In the case where the determination result is not less than, the function verification result is determined to be a parameter indicating that the verification has failed.

[0109] In this embodiment, when the grid-connected parameters of the power grid simulator are adjusted to meet the function verification triggering conditions, it is determined whether the output power of the inverter is within the specified power range. If so, the output parameters of the AC side of the inverter are obtained, and based on the output parameters, the off-grid time point that meets the set current rule is determined, and it is determined whether the off-grid time meets the off-grid time rule, and the function verification result is determined based on the determination result; the off-grid time is determined based on the time point of adjusting the grid-connected parameters of the power grid simulator and the off-grid time point. That is, in the present invention, the over-voltage / under-frequency protection function can be automatically verified, and the verification is based on the output parameters of the AC side of the inverter, which can improve accuracy and efficiency compared to the manual function verification method.

[0110] In addition, in the embodiment of the present invention, intelligent judgment of the AC side waveform in the inverter over-voltage / under-frequency protection function test is realized, which not only does not require the tester to concentrate on visual monitoring throughout the process, but also uses a combination of various means to accurately find the moment when the inverter is disconnected from the grid; the entire process uses a functional verification system to integrate various bus technologies and database technologies to achieve fully automated operation, without any human intervention in the middle, greatly shortening the test cycle.

[0111] In addition, the embodiment of the present invention uses independently written software to realize the control and monitoring of the entire verification system and inverter, so as to achieve the goal of unmanned operation; it can accurately find the current signal point when the inverter is disconnected from the grid, and combine the voltage / frequency change signal point. The software platform can automatically determine whether the inverter over-voltage / under-frequency protection function meets the relevant standard requirements, and can automatically upload waveform data and generate reports after the judgment is completed.

[0112] The above content mentioned "determining the off-grid time point that meets the set current rule based on the output parameters", and now introduces its specific implementation process. Figure 3 , which may include:

[0113] S21. Acquire a current value of a first sampling point in the output parameter and current values ​​of second sampling points located a specified number of times after the first sampling point.

[0114] In this embodiment, when the oscilloscope performs data acquisition, the data is acquired at a specific sampling rate, and each acquisition is called a sampling point, and the sampling point corresponds to the acquired output parameter.

[0115] When performing subsequent data analysis, the data analysis may be performed by a computing unit inside the controller, or by a computing unit external to the controller.

[0116] In this embodiment, the sampling points are sequentially used as the first sampling points, and then the current values ​​of the sampling points located at a specified number after the first sampling point are obtained. For the sake of distinction, the sampling points located after the first sampling point are called second sampling points. That is, in this embodiment, the current values ​​of the second sampling points located at a specified number after the first sampling point are obtained. The specified number can be set according to the actual scenario. That is, in this embodiment, as long as the second sampling points that meet the specified number are selected after the first sampling point, it will be fine.

[0117] It should be noted that if the data amount of the second sampling point after the first sampling point is less than the specified amount, the first sampling point and the subsequent first sampling points may not be analyzed.

[0118] In an implementation of the present invention, it may be that: current values ​​of second sampling points, which are a first specified number and are located in a specified current cycle after the first sampling point, are acquired.

[0119] The specified current cycle may be the first current cycle after the first sampling point, the first two current cycles, the first three current cycles, etc. The specific implementation is set according to the actual scenario.

[0120] More specifically, current values ​​of second sampling points, which are located in the first current cycle after the first sampling point and are uniformly distributed and have a first specified number, may be acquired.

[0121] In this embodiment, the data in the first current cycle is collected because the current data read from the oscilloscope is real-time data, and the value of the data changes periodically between the maximum amplitude and the minimum amplitude to form a sine curve. During the normal grid-connected operation of the inverter, points where the current value is less than the interference threshold Is or equal to 0 are also periodically collected. Therefore, it is not possible to directly determine whether the point is an off-grid point simply by whether the value of a single sampling point is less than the interference threshold Is. In this embodiment, based on the characteristics of the AC waveform, a current cycle after the first sampling point is selected, such as a second sampling point within the waveform cycle time period and with a suitable number. The intervals between the second sampling points are preferably uniformly spaced. Within a suitable range of numbers, the first sampling point and the second sampling point can equivalently cover the range of instantaneous current values ​​within a waveform cycle. The above-mentioned problems are effectively solved by adopting this method.

[0122] It should be noted that, in the present embodiment, it is preferred to use sampling points within a current cycle because at the moment of disconnection from the network, the network may not be disconnected successfully in a short period of time, but after a long time, the network is disconnected successfully. Therefore, according to analysis, the data of the sampling point far away from the first sampling point has a large error in determining whether the network is successfully disconnected, while the data close to the first sampling point can well determine whether the data of the first sampling point is successfully disconnected from the network, and the accuracy is higher.

[0123] The first specified number may be 7, plus the first sampling point, which is a total of 8 output parameters, which just constitutes a current cycle.

[0124] When determining the current value, the uniformly distributed second sampling point is used. Specifically, since the AC side current of an inverter, such as a photovoltaic inverter, is a sine wave, the current value read during normal grid-connected operation is also 0, so it is impossible to determine the off-grid time point by simply judging whether it is zero. At this time, through reasonable calculation, when determining whether a point (i.e., the first sampling point) is the off-grid time point, 7 points with a period of 1 / 8, 2 / 8 (1 / 4), 3 / 8, 4 / 8 (1 / 2), 5 / 8, 6 / 8 (3 / 4), and 7 / 8 from the point will be selected and determined at the same time.

[0125] In another implementation of the present invention, current values ​​of second sampling points, which are located in the first current cycle after the first sampling point and whose number is a first specified number and which are unevenly distributed, may also be acquired.

[0126] Different from the previous embodiment, in this embodiment, as long as seven second sampling points are selected in the first current cycle after the first sampling point, they can be selected randomly, such as selecting seven consecutively, or at intervals.

[0127] That is to say, when selecting the second sampling point, it is only necessary to ensure that within the first current cycle, whether it is uniform selection or non-uniform selection, both are feasible means. However, preferably, a uniform selection method is adopted, which can reduce the possibility of misjudgment and avoid the situation where the network failure is considered due to non-uniform selection (such as all close to the first sampling point). In actual applications, the second sampling points in the same cycle after the first sampling point may all meet the network disconnection rules, and only the current value near the first sampling point is large, which will lead to misjudgment of network disconnection.

[0128] After determining the first and second sampling points, obtaining the current value of each of the first and second sampling points,

[0129] S22, determining whether all the acquired current values ​​meet the preset current rule; if so, executing step S23.

[0130] Specifically, there is interference data in the data read by the oscilloscope, and the current data read even after disconnection from the grid contains non-zero data. Therefore, an interference threshold Is is obtained by processing the current data for a period of time after disconnection from the grid. The interference threshold Is can be the maximum absolute current value in the output parameters of the inverter, such as the AC side of the photovoltaic inverter, within the third specified time range after adjusting the grid connection parameters of the grid simulator. The third specified time range can be set according to the actual scenario.

[0131] An interference threshold value Is is obtained by processing the current data for a period of time after being disconnected from the grid (generally, the output current of the photovoltaic inverter should be around 0 after being disconnected from the grid, and the interference threshold value Is in this embodiment should be a value close to 0). This is because the current fluctuations of different photovoltaic inverters when disconnected from the grid are not necessarily the same. Therefore, in this embodiment, a current threshold value suitable for all photovoltaic inverters is not selected, but an interference threshold value Is is obtained by processing the current data for a period of time after being disconnected from the grid.

[0132] The above-mentioned interference threshold Is is the preset current threshold in this embodiment. In addition, the preset current threshold can also be a current threshold suitable for the photovoltaic inverter obtained by manually analyzing the current data of a period of time after the photovoltaic inverter is disconnected from the grid.

[0133] After setting the above-mentioned preset current threshold, determine whether all the current values ​​obtained are less than the preset current threshold. In this embodiment, it is to determine whether the values ​​of the above-mentioned 8 sampling points are all lower than Is. If satisfied, it means that the verification is passed, and the current values ​​of the first sampling point and the second sampling point after the first sampling point are both less than the interference threshold Is, that is, the current values ​​of the first sampling point and the second sampling point after the first sampling point fluctuate around 0, indicating that at the first sampling point, the photovoltaic inverter may be successfully disconnected from the grid.

[0134] S23: taking the time point corresponding to the first sampling point that earliest meets the preset current rule as the off-grid time point.

[0135] That is to say, when the first sampling point and the second sampling point that appear earliest satisfy that the current values ​​are both less than the interference threshold Is, it means that at the first sampling point, the photovoltaic inverter may be successfully disconnected from the grid. At this time, the time point corresponding to the first sampling point can be used as the disconnection time point.

[0136] The accuracy of the above-mentioned off-grid time point may be problematic. In another implementation of the present invention, the time point corresponding to the first sampling point that earliest meets the preset current rule can be used as the initial off-grid time point, and the initial off-grid time point can be verified. After the verification passes, the initial off-grid time point can be used as the off-grid time point.

[0137] Specifically, refer to Figure 4 , verifying the offline time point may include:

[0138] S31, obtaining a second specified number of third sampling points that are consecutive after the first sampling point corresponding to the initial offline time point.

[0139] In this embodiment, the above embodiment preliminarily determines the first sampling point as the initial off-grid point, and this moment is the off-grid time point. The off-grid point selected at this time still has a large error in some cases. Specifically, if the instantaneous value of the current at the previous sampling point of the off-grid point of the over-voltage / under-frequency function of the photovoltaic inverter (the value on the current waveform) is less than the interference threshold Is, there will be an error between the initial off-grid point determined for the first time and the actual off-grid point. If the interference threshold Is is close to the maximum instantaneous value of the current in the last cycle, the maximum error can be close to the size of 1 / 2 cycle of the current waveform; or the peak value of the last few cycles of the current waveform before the actual off-grid of the photovoltaic inverter is close to the Is value. When the position of the first sampling point is located at 3 / 16 of the waveform cycle and the value is just less than Is, and the interval between the multiple points of the second sampling point is just 1 / 8 of the waveform cycle, the first sampling point and the second sampling point will completely avoid the current value near the peak, and the current value in this time period will be greater than Is, resulting in the determined off-grid point moving forward by a corresponding time than the actual one.

[0140] In order to avoid the above error, a second specified number of third sampling points after the first sampling point can be continuously selected, and the second specified number can be set according to the actual scenario, such as 9 or 19. Including the first sampling point, there are 10 or 20 data in total.

[0141] S32, determining whether the current values ​​of the first sampling point corresponding to the initial off-grid time point and all the third sampling points meet the set current relationship rule; if so, executing step S33.

[0142] Specifically, the waveform of the error part is a normal sinusoidal waveform, and the read value conforms to the sinusoidal change; while the waveform containing interference after disconnection from the grid is an irregular and discrete waveform; at this time, a specific number of current values ​​subsequent to the first sampling point can be intercepted to calculate the root mean square value of the collection to determine whether a normal waveform still exists after the first sampling point.

[0143] In this embodiment, the root mean square value and the average value of the absolute value of the current value at the first sampling point corresponding to the off-grid time point and all the third sampling points may be calculated.

[0144] Then, it is determined whether the ratio of the root mean square value to the average value is greater than a preset ratio threshold.

[0145] In this embodiment, the preset ratio threshold may be 0.3, which is a more reasonable value determined by analyzing a specific scenario.

[0146] That is, in this embodiment, the root mean square value and the arithmetic mean value of the above 10 points are calculated. When the ratio of the two is higher than 0.3, it is considered that the selected off-line time point meets the accuracy requirement.

[0147] S33: Determine whether the initial offline time point check passes.

[0148] If so, the ratio of the root mean square value to the average value is greater than 0.3, it is considered that the offline time point meets the accuracy requirement and passes the verification, that is, it is the accurate offline time point.

[0149] After the initial offline time point verification passes, the initial offline time point can be determined as the offline time point, and the offline time is calculated according to the offline time point, and it is determined whether the offline time meets the offline time rule.

[0150] If the verification fails, then select a point after the initial off-line point confirmed in step S23, execute step S32, and loop in sequence until the verification of step S32 passes, that is, confirm that the point is the off-line time point.

[0151] In order for those skilled in the art to clearly understand the present invention, Figure 5-7 In practical applications, when the voltage / frequency of the power grid reaches the over-voltage / under-voltage / over-frequency protection function judgment value of the photovoltaic inverter and the photovoltaic inverter responds normally to the off-grid operation, there may be three situations. One is that after the photovoltaic inverter triggers the off-grid operation, the instantaneous value of the current waveform directly changes to 0 at a position greater than the interference threshold Is (a phenomenon of jumping near 0 may occur due to interference).

[0152] This situation can refer to Figure 5, there is no sine wave after the initial off-grid point determined in step S23, and the last sampling point in the last cycle of this sine wave is greater than the interference threshold. After the initial off-grid point is determined in step S23, the point is checked for accuracy of the initial off-grid point in step S32. Since there is no sine wave after this point, the first check in step S32 passes directly. At this time, the initial off-grid point determined for the first time is the same point as the off-grid time point.

[0153] Another situation is that after the photovoltaic inverter triggers the off-grid action, the current waveform suddenly changes to 0 at the position where the instantaneous current value is less than the interference threshold Is (it may jump near 0 due to interference), such as Figure 6 .

[0154] This situation can refer to Figure 6 , the initial off-grid point is determined according to step S23, but there may still be a large error between the initial off-grid point and the actual off-grid point. Because at this time, the instantaneous value of the current on the sine wave between the initial off-grid point determined in step S23 and the actual off-grid point is less than the interference threshold Is, but there is still a sine waveform. At this time, when the initial off-grid point is checked for accuracy according to step S32, it is determined that it cannot pass. At this time, the subsequent current points of the initial off-grid point need to be checked in sequence according to step S32 until the check passes, and the point that passes is the off-grid point (considering the sampling rate of the oscilloscope, the time accuracy of this point fully meets the requirements of the over-undervoltage / over-underfrequency function check).

[0155] There is another situation where the peak value of the current waveform in the last few cycles after the photovoltaic inverter triggers the off-grid action is close to the Is value, such as Figure 7 .

[0156] This situation can refer to Figure 7 , when the first sampling point is located at 3 / 16 of the waveform cycle and the value is just less than Is, and the second sampling point is just starting from the 5 / 16 cycle position and the interval is 1 / 8 cycle, the first sampling point and the second sampling point will completely avoid the current value greater than Is near the peak, resulting in a large error. As shown in the figure, a1 is the first sampling point, a2 is the first point in the second sampling point, a3 is the fourth point in the second sampling point, and a4 is the fifth point in the second sampling point. The instantaneous value of the current between a1 and a2 is greater than the interference threshold Is, but step S23 will determine a1 as the initial off-grid point due to the particularity of the point selection. When the initial off-grid point is checked for accuracy according to step S32, it is determined that it cannot pass. Then, the subsequent sampling points of the initial off-grid point are checked in turn according to step S32 until the check passes, and the point that passes is the actual off-grid point (considering the sampling rate of the oscilloscope, the time accuracy of this point fully meets the requirements of the over-undervoltage / over-underfrequency function check).

[0157] In this embodiment, the off-grid time point is determined based on the current value at the sampling point, and the off-grid time point is verified to obtain an accurate off-grid time point.

[0158] Optionally, based on the above-mentioned embodiment of the function verification method, another embodiment of the present invention provides a function verification device, which is applied to a controller, referring to Figure 8 , the functional verification device comprises:

[0159] The power determination module 11 is used to determine whether the output power of the inverter is within a specified power range when the grid connection parameters of the power grid simulator are adjusted to meet the function verification triggering conditions;

[0160] A time point determination module 12 is used to obtain the output parameters of the AC side of the inverter, and determine the off-grid time point that meets the set current rule based on the output parameters;

[0161] The function verification module 13 is used to determine whether the off-grid time meets the off-grid time rule, and determine the function verification result based on the determination result; the off-grid time is determined based on the time point of adjusting the grid connection parameters of the power grid simulator and the off-grid time point.

[0162] Furthermore, the time point determination module 12 is used to obtain the output parameters of the inverter AC side, specifically for:

[0163] The output parameters after the specified time point before the grid connection parameters of the power grid simulator are adjusted and satisfy the specified data volume display rules are obtained.

[0164] Further, the time point determination module 12 is used to determine the off-grid time point that meets the set current rule based on the output parameter, specifically for:

[0165] A current acquisition submodule, used to acquire a current value of a first sampling point in the output parameter, and current values ​​of a second sampling point located a specified number of times after the first sampling point;

[0166] A rule determination submodule is used to determine whether all the acquired current values ​​meet the preset current rules;

[0167] The time point determination submodule is used to take the time point corresponding to the first sampling point that earliest meets the preset current rule as the off-grid time point if the condition is met.

[0168] Furthermore, the current acquisition submodule is used to acquire the current value of the second sampling points located a specified number of times after the first sampling point, specifically to:

[0169] Current values ​​of second sampling points, which are a first specified number and are located after the first sampling point, are acquired within a specified current cycle.

[0170] Furthermore, the current acquisition submodule is used to acquire the current values ​​of the second sampling points, which are a first specified number, within a specified current cycle after the first sampling point, and is specifically used to:

[0171] Acquire current values ​​of second sampling points, which are a first specified number and evenly distributed within a first current cycle after the first sampling point;

[0172] or,

[0173] Current values ​​of second sampling points, which are located in a first current cycle after the first sampling point and are unevenly distributed and have a first specified number, are acquired.

[0174] Furthermore, the rule determination submodule is specifically used for:

[0175] Determine whether all the acquired current values ​​are less than a preset current threshold;

[0176] The preset current threshold is a preset current value, or a maximum absolute current value of the output parameters of the AC side of the inverter within a third specified time range after the grid connection parameters of the power grid simulator are adjusted.

[0177] Furthermore, the time point determination submodule is specifically used for:

[0178] The time point corresponding to the first sampling point that earliest meets the preset current rule is used as the initial off-grid time point, the initial off-grid time point is verified, and after the verification passes, the initial off-grid time point is used as the off-grid time point.

[0179] Further, when the time point determination submodule is used to verify the initial off-line time point, it is specifically used to:

[0180] After obtaining the first sampling point corresponding to the initial off-grid time point, a second specified number of third sampling points are consecutively obtained to determine whether the current values ​​of the first sampling point corresponding to the initial off-grid time point and all the third sampling points meet the set current relationship rule; if so, it is determined that the initial off-grid time point check passes.

[0181] Further, the time point determination submodule is used to determine whether the current values ​​of the first sampling point corresponding to the initial off-grid time point and all the third sampling points meet the set current relationship rule, specifically for:

[0182] Calculate the root mean square value and the average value of the absolute value of the current value of the first sampling point corresponding to the initial off-grid time point and all the third sampling points, and determine whether the ratio of the root mean square value to the average value is greater than a preset ratio threshold.

[0183] Further, the function verification module 13 is specifically used for:

[0184] Determine whether the offline time is less than a preset offline time threshold to obtain a determination result. If the determination result is less than, determine the function verification result as a parameter that characterizes the verification is passed.

[0185] Furthermore, it also includes:

[0186] The instruction sending module is used for sending an amplification instruction including the off-grid time point to the oscilloscope after the function verification module 13 determines the function verification result based on the determination result, so that the oscilloscope responds to the amplification instruction, amplifies the current waveform including the off-grid time point and takes a screenshot, and uploads the captured picture to the controller.

[0187] Furthermore, it also includes: a parameter determination module, which is used to determine that the function verification result is a parameter that indicates that the verification has failed when it is determined that the output power of the inverter is not within the specified power range.

[0188] In this embodiment, when the grid-connected parameters of the power grid simulator are adjusted to meet the function verification triggering conditions, it is determined whether the output power of the inverter is within the specified power range. If so, the output parameters of the AC side of the inverter are obtained, and based on the output parameters, the off-grid time point that meets the set current rule is determined, and it is determined whether the off-grid time meets the off-grid time rule, and the function verification result is determined based on the determination result; the off-grid time is determined based on the time point of adjusting the grid-connected parameters of the power grid simulator and the off-grid time point. That is, in the present invention, the over-voltage / under-frequency protection function can be automatically verified, and the verification is based on the output parameters of the AC side of the inverter, which can improve accuracy and efficiency compared to the manual function verification method.

[0189] It should be noted that, for the working process of each module and sub-module in this embodiment, please refer to the corresponding description in the above embodiment, which will not be repeated here.

[0190] Optionally, based on the above-mentioned embodiments of the function verification method and device, another embodiment of the present invention provides a controller for executing the above-mentioned function verification method.

[0191] Optionally, based on the above-mentioned embodiments of the function verification method and device, another embodiment of the present invention provides a function verification system, including an inverter and the above-mentioned controller; the inverter is connected to the controller.

[0192] Furthermore, the functional verification system also includes:

[0193] Power analyzer and oscilloscope;

[0194] The power analyzer and the oscilloscope are connected to the controller and the inverter respectively;

[0195] The power analyzer is used to collect output parameters of the inverter and send them to the controller;

[0196] The oscilloscope is used to receive a zoom instruction including the off-grid time point sent by the controller, respond to the zoom instruction, zoom in and capture the current waveform including the off-grid time point, and upload the captured image to the controller.

[0197] Furthermore, the functional verification system also includes:

[0198] A photovoltaic simulation power supply and a power grid simulator, wherein the photovoltaic simulation power supply and the power grid simulator are respectively connected to the controller; the photovoltaic simulation power supply is connected to the DC side of the inverter, and the power grid simulator is connected to the AC side of the inverter.

[0199] It should be noted that for the specific implementation process of each device in this embodiment, please refer to the corresponding description in the above embodiment.

[0200] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A function verification method, characterized in that: Applied to the controller, the function verification method includes: When the grid-connected parameters of the power grid simulator are adjusted to meet the function verification triggering conditions, determining whether the output power of the inverter is within the specified power range; If so, obtaining the output parameters of the inverter AC side, and determining the off-grid time point that satisfies the set current rule based on the output parameters; Determine whether the off-grid time satisfies the off-grid time rule, and determine the function verification result based on the determination result; the off-grid time is determined based on the time point of adjusting the grid connection parameters of the power grid simulator and the off-grid time point; Wherein, based on the output parameters, determining the off-grid time point that satisfies the set current rule includes: Acquire a current value of a first sampling point in the output parameter, and a current value of a second sampling point located a specified number of times after the first sampling point; Determine whether all the acquired current values ​​meet the preset current rules; If so, the time point corresponding to the first sampling point that earliest meets the preset current rule is used as the off-grid time point.

2. The function verification method according to claim 1, characterized in that: Obtaining output parameters of the AC side of the inverter, including: The output parameters after the specified time point before the grid connection parameters of the power grid simulator are adjusted and satisfy the specified data volume display rules are obtained.

3. The function verification method according to claim 1, characterized in that: Obtaining current values ​​of second sampling points located a specified number of times after the first sampling point, comprising: Current values ​​of second sampling points, which are a first specified number and are located after the first sampling point, are acquired within a specified current cycle.

4. The function verification method according to claim 3, characterized in that: Acquiring current values ​​of a first specified number of second sampling points within a specified current cycle after the first sampling point includes: Acquire current values ​​of second sampling points, which are a first specified number and uniformly distributed within a first current cycle after the first sampling point; or, Current values ​​of second sampling points, which are a first specified number and unevenly distributed, are acquired within a first current cycle after the first sampling point.

5. The function verification method according to claim 1, characterized in that: Determine whether all current values ​​obtained meet the preset current rules, including: Determine whether all the acquired current values ​​are less than a preset current threshold; The preset current threshold is a preset current value, or a maximum absolute current value of the output parameters of the AC side of the inverter within a third specified time range after the grid connection parameters of the power grid simulator are adjusted.

6. The function verification method according to claim 1, characterized in that: The time point corresponding to the first sampling point that earliest meets the preset current rule is used as the off-grid time point, including: The time point corresponding to the first sampling point that earliest meets the preset current rule is used as the initial off-grid time point; The initial offline time point is verified, and after the verification passes, the initial offline time point is used as the offline time point.

7. The function verification method according to claim 6, characterized in that: Verifying the initial off-network time point includes: Acquire a second specified number of third sampling points that are consecutive after the first sampling point corresponding to the initial offline time point; Determine whether the current values ​​of the first sampling point corresponding to the initial off-grid time point and all the third sampling points meet the set current relationship rule; If so, it is determined that the initial offline time point check has passed.

8. The function verification method according to claim 7, characterized in that: Determining whether the current values ​​of the first sampling point corresponding to the initial off-grid time point and all the third sampling points satisfy a set current relationship rule includes: Calculate the root mean square value and the average value of the absolute value of the current value at the first sampling point corresponding to the initial off-grid time point and all the third sampling points; It is determined whether a ratio of the root mean square value to the average value is greater than a preset ratio threshold.

9. The function verification method according to claim 1, characterized in that: Determine whether the offline time meets the offline time rule, and determine the function verification result based on the determination result, including: Determine whether the offline time is less than a preset offline time threshold, and obtain a determination result; In the case where the determination result is less than, the function verification result is determined to be a parameter indicating that the verification has passed.

10. The function verification method according to claim 1, characterized in that: After determining the function verification result based on the determination result, the method further includes: An amplification instruction including the off-grid time point is sent to the oscilloscope, so that the oscilloscope responds to the amplification instruction, amplifies and captures the current waveform including the off-grid time point, and uploads the captured image to the controller.

11. The function verification method according to claim 1, characterized in that: When it is determined that the output power of the inverter is not within the specified power range, the method further includes: The functional verification result is determined to be a parameter that characterizes the failure of the verification.

12. A functional verification device, characterized in that: Applied to a controller, the function verification device comprises: A power determination module is used to determine whether the output power of the inverter is within a specified power range when the grid connection parameters of the power grid simulator are adjusted to meet the function verification triggering conditions; A time point determination module, for obtaining the output parameters of the AC side of the inverter, and determining the off-grid time point that satisfies the set current rule based on the output parameters; A function verification module, used to determine whether the off-grid time satisfies the off-grid time rule, and determine a function verification result based on the determination result; the off-grid time is determined based on the time point of adjusting the grid connection parameters of the power grid simulator and the off-grid time point; The time point determination module determines the off-grid time point that satisfies the set current rule based on the output parameter, including: Acquire a current value of a first sampling point in the output parameter, and a current value of a second sampling point located a specified number of times after the first sampling point; Determine whether all the acquired current values ​​meet the preset current rules; If so, the time point corresponding to the first sampling point that earliest meets the preset current rule is used as the off-grid time point.

13. A controller, characterized in that: Used to execute the function verification method as described in any one of claims 1-11.

14. A function verification system, characterized in that: It comprises an inverter and a controller as claimed in claim 13; the inverter is connected to the controller.

15. The function verification system according to claim 14, characterized in that: Also includes: Power analyzer and oscilloscope; The power analyzer and the oscilloscope are connected to the controller and the inverter respectively; The power analyzer is used to collect the output power of the inverter and send it to the controller; The oscilloscope is used to collect the output parameters of the inverter and send them to the controller, receive the amplification instruction including the off-grid time point sent by the controller, respond to the amplification instruction, amplify and capture the current waveform including the off-grid time point, and upload the captured image to the controller.

16. The function verification system according to claim 14, characterized in that: Also includes: A photovoltaic simulation power supply and a power grid simulator, wherein the photovoltaic simulation power supply and the power grid simulator are respectively connected to the controller; the photovoltaic simulation power supply is connected to the DC side of the inverter, and the power grid simulator is connected to the AC side of the inverter.

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