An adaptive overcurrent protection method and system for frequency converters

Abstract

The application discloses a kind of adaptive frequency converter overcurrent protection method and system, it is related to wind turbine monitoring technical field, the method includes: obtaining frequency converter initial overcurrent protection parameter;Monitoring data set including current data set, vibration data set, monitoring temperature set is collected;Current data set is analyzed to current state, obtains current trend value;Respectively to vibration data set and monitoring temperature set are fitted, obtain auxiliary fluctuation factor;Whether current trend value is in the first level early warning bandwidth of overload current threshold, if yes, obtain first early warning instruction, trigger overcurrent protection action;If no, and current trend value is in the second level early warning bandwidth of overload current threshold, whether auxiliary fluctuation factor satisfies preset threshold, if yes, then obtain second early warning instruction, according to second early warning instruction trigger overcurrent protection action.The technical effect of improving threshold response flexibility, fast overcurrent protection response is realized.

Description

Technical Field

[0001] This invention relates to the field of wind turbine monitoring technology, and in particular to an adaptive inverter overcurrent protection method and system. Background Technology

[0002] With the rapid development of power electronics technology, frequency converters have been widely used in industrial automation, energy, transportation and other fields. As a core component of motor drive systems, frequency converters can achieve functions such as stepless speed regulation of motors and energy saving.

[0003] In actual operation, frequency converters may encounter various faults, among which overcurrent faults are the most common. Overcurrent faults can not only damage equipment but also affect production safety and efficiency. Existing overcurrent protection methods mainly rely on setting a fixed protection threshold, triggering protection when the current exceeds the threshold. While this method is simple and easy to implement, it also suffers from technical problems such as difficulty in setting the threshold and slow response speed. Summary of the Invention

[0004] This invention provides an adaptive overcurrent protection method and system for frequency converters to solve the technical problems of difficult threshold setting and slow response speed in the prior art, thereby achieving the technical effect of improving threshold response flexibility and fast overcurrent protection response.

[0005] In a first aspect, the present invention provides an adaptive overcurrent protection method for a frequency converter, wherein the method includes: The initial overcurrent protection parameters of the frequency converter are interactive, wherein the initial overcurrent protection parameters include an overload current threshold and an overload delay window; Collect a set of monitoring data of the target frequency converter within a preset monitoring window, wherein the set of monitoring data includes a current dataset, a vibration dataset, and a monitoring temperature dataset; Based on the current values ​​in the current dataset, current state analysis is performed to obtain current trend values; Auxiliary fluctuation factors are obtained by performing fluctuation fitting on the vibration dataset and the monitored temperature dataset, respectively. Determine whether the current trend value is within the first-level warning bandwidth of the overload current threshold. If so, obtain the first warning instruction and trigger the overcurrent protection action according to the first warning instruction. If not, when the current trend value is within the secondary warning bandwidth of the overload current threshold, determine whether the auxiliary fluctuation factor meets the preset threshold. If so, obtain the second warning instruction and trigger the overcurrent protection action according to the second warning instruction.

[0006] Secondly, the present invention also provides an adaptive inverter overcurrent protection system, wherein the system comprises: The protection parameter extraction module is used to interact with the initial overcurrent protection parameters of the frequency converter, wherein the initial overcurrent protection parameters include an overload current threshold and an overload delay window; The monitoring and acquisition module is used to acquire a set of monitoring data of the target frequency converter within a preset monitoring window, wherein the set of monitoring data includes a current dataset, a vibration dataset, and a monitoring temperature dataset. A trend analysis module is used to perform current state analysis based on the current values ​​in the current dataset to obtain current trend values. A fluctuation fitting module is used to perform fluctuation fitting on the vibration dataset and the monitored temperature dataset respectively to obtain an auxiliary fluctuation factor. A first-level early warning module is used to determine whether the current trend value is within the first-level early warning bandwidth of the overload current threshold. If so, a first early warning instruction is obtained, and an overcurrent protection action is triggered according to the first early warning instruction. The second early warning module is used to determine whether the auxiliary fluctuation factor meets the preset threshold when the current trend value is within the secondary early warning bandwidth of the overload current threshold. If yes, a second early warning instruction is obtained, and overcurrent protection action is triggered according to the second early warning instruction.

[0007] This invention discloses an adaptive overcurrent protection method and system for frequency converters, comprising: interacting with the frequency converter to obtain initial overcurrent protection parameters including an overload current threshold and an overload delay window; collecting monitoring data of the frequency converter within a preset monitoring window, including current data, vibration data, and monitored temperature; analyzing the current state based on the current data to obtain a current trend value; performing fluctuation fitting on the vibration data and monitored temperature to obtain an auxiliary fluctuation factor; determining whether the current trend value is within the first-level warning bandwidth of the overload current threshold, and if so, triggering a first-level warning command; if not, and the current trend value is within the second-level warning bandwidth of the overload current threshold, determining whether the auxiliary fluctuation factor meets a preset threshold, and triggering a second-level warning command if it does. This adaptive overcurrent protection method and system for frequency converters solves the technical problems of difficult threshold setting and slow response speed, achieving improved threshold response flexibility and rapid overcurrent protection response. Attached Figure Description

[0008] Figure 1 This is a flowchart illustrating an adaptive inverter overcurrent protection method according to the present invention. Figure 2 This is a schematic diagram of the structure of an adaptive frequency converter overcurrent protection system according to the present invention.

[0009] Explanation of reference numerals in the attached diagram: 11. Protection parameter extraction module; 12. Monitoring and acquisition module; 13. Trend analysis module; 14. Fluctuation fitting module; 15. First-level early warning module; 16. Second-level early warning module. Detailed Implementation

[0010] The technical solutions provided in the embodiments of the present invention address the technical problems of difficulty in setting thresholds and slow response speed in the prior art. The overall approach adopted is as follows: First, initial overcurrent protection parameters, including overload current threshold and overload delay window, are obtained through the interactive frequency converter. Next, monitoring data from the target frequency converter within a preset monitoring window is collected; this data includes current datasets, vibration datasets, and monitored temperature datasets. Then, current state analysis is performed using the current values ​​from the current dataset to obtain current trend values. Subsequently, fluctuation fitting is performed on the vibration dataset and monitored temperature dataset to obtain an auxiliary fluctuation factor. Then, it is determined whether the current trend value is within the first-level warning bandwidth of the overload current threshold. If so, a first warning command is obtained, and overcurrent protection action is triggered according to the first warning command. If the current trend value is not within the first-level warning bandwidth but is within the second-level warning bandwidth of the overload current threshold, it is determined whether the auxiliary fluctuation factor has reached a preset threshold. If so, a second warning command is obtained, and overcurrent protection action is executed according to this command.

[0011] The above technical solutions will now be described in detail with reference to the accompanying drawings and specific embodiments to provide a better understanding of them. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be understood that the present invention is not limited to the exemplary embodiments used only to explain the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the drawings, not all of them.

[0012] Example 1 Figure 1 This is a flowchart illustrating an adaptive inverter overcurrent protection method according to the present invention; wherein, it includes: The initial overcurrent protection parameters of the frequency converter are interactive, wherein the initial overcurrent protection parameters include an overload current threshold and an overload delay window; Overcurrent protection is an important safety measure to protect frequency converters and frequency converter control equipment. Optionally, the overcurrent protection of the frequency converter is achieved by setting the overload current threshold and the overload delay window. In other words, the initial overcurrent protection parameters of the frequency converter are the overload current threshold and the corresponding overload delay window.

[0013] The overload current threshold reflects the magnitude of the current requiring protection, while the overload delay window refers to the duration of the overload current requiring protection. In other words, protection is triggered when the overcurrent magnitude of the target inverter exceeds the overload current threshold, and protection is executed when the overcurrent magnitude exceeds the overload current threshold for a duration greater than the overload delay window. Specifically, protection actions include reducing the output frequency or stopping the output.

[0014] Optionally, the initial overcurrent protection parameters include multiple sets of matched overload current thresholds and overload delay windows. The matching of the overload current threshold and overload delay window is based on the thermal effect of current on the inverter. Higher overload current thresholds correspond to shorter overload delay windows, while lower overload current thresholds correspond to longer overload delay windows. Through this setting, the inverter can cope with overcurrent protection scenarios of various overcurrent levels and durations, improving the coverage of overcurrent protection.

[0015] Collect a set of monitoring data of the target frequency converter within a preset monitoring window, wherein the set of monitoring data includes a current dataset, a vibration dataset, and a monitoring temperature dataset; The monitoring window is a specific time period during which monitoring data of the frequency converter is collected and stored. Preset monitoring windows have corresponding window parameters, including the duration of the monitoring window and its start or end time.

[0016] Optionally, the monitoring data set collected during the monitoring window includes: a current dataset, which refers to the set of magnitude values ​​of the inverter current during the monitoring window; a vibration dataset, which records the vibration data of the inverter and its drive motor during the monitoring window, including the amplitude, frequency and phase of the vibration; and a monitoring temperature set, which reflects the temperature performance of the inverter and its related components within the monitoring window.

[0017] Optionally, monitoring data can be collected using various monitoring sensors installed on the target frequency converter. Specifically, the monitoring sensors include current sensors (such as Hall effect sensors), vibration sensors (such as piezoelectric or accelerometers), and temperature sensors (such as thermocouples or infrared sensors).

[0018] Through the above methods and settings, the inverter monitoring data was acquired to monitor the health status of the equipment and provide data support for subsequent overcurrent detection.

[0019] Based on the current values ​​in the current dataset, current state analysis is performed to obtain current trend values; Optionally, the current values ​​in the current dataset represent multiple fluctuating current magnitudes. Therefore, through current state analysis, representative current values ​​are obtained and stored as current trend values. In other words, the current trend values ​​are typical values ​​of multiple current values ​​in the current dataset and can represent the current level of the current dataset.

[0020] For example, current state analysis is based on statistical and mathematical methods. First, the current data is cleaned by removing outliers and noise. Then, data smoothing techniques such as moving averages, exponential smoothing, or low-pass filters are used to reduce random fluctuations in the data and make the trend more apparent. Finally, statistical analysis methods are used to extract characteristic values, including the mean, median, mode, or standard deviation, from the smoothed current data to determine the trend values.

[0021] In some embodiments, current state analysis is performed based on the current values ​​in the current dataset to obtain current trend values. The method includes: N current values ​​are extracted from the current dataset, and a two-dimensional space for current distribution is constructed with time as the horizontal axis, current value as the vertical axis, and N current values ​​as N coordinate points. The straight line that passes through the average of the N current values ​​and is parallel to the horizontal axis is taken as the first trend line. The two-dimensional space of the current distribution is divided into an upper space and a lower space using the first trend line. By comparing the number of coordinate points in the upper space and the lower space, and based on the position of the space with more coordinate points relative to the first trend line, the first trend direction is obtained, wherein the first trend direction includes an upward movement indicator and a downward movement indicator; Based on the first trend direction and the first trend line, current state analysis is performed in the two-dimensional space of the current distribution to obtain the current trend value.

[0022] Optionally, the current dataset consists of current values ​​from multiple sampling points acquired based on a preset sampling rate. The number N of current values ​​in the current dataset is determined based on the monitoring window length and the sampling rate, where N is the ratio of the monitoring window length to the sampling rate plus 1. The N current values ​​in the current dataset have sampling time sequence markers.

[0023] For example, firstly, a parameter space is constructed based on a Cartesian coordinate system, where the horizontal axis represents sampling time and the vertical axis represents the current value, forming a two-dimensional space for current distribution. Then, the mean value 'a' of the N current values ​​is calculated, and the first trend line is represented as y = a. Furthermore, based on the first trend line, the two-dimensional space of current distribution is divided into an upper space and a lower space. The upper space refers to the region where all current values ​​are greater than the coordinates of the first trend line, represented as y > a; the lower space refers to the region where all current values ​​are less than the coordinates of the first trend line, represented as y < a.

[0024] Optionally, the number of coordinate points in the upper and lower spaces can be compared. If the number of coordinate points in the upper space is greater than that in the lower space, the first trend direction is represented by an upward movement indicator; if the number of coordinate points in the lower space is greater than that in the upper space, the first trend direction is represented by a downward movement indicator.

[0025] In some implementations, based on the first trend direction and the first trend line, current state analysis is performed in the two-dimensional space of the current distribution to obtain the current trend value. The method includes: Based on the first trend direction, the first trend line is moved according to a preset moving step size to obtain the first moving line; Based on the first trend direction, the first moving straight line is moved according to the preset moving step size to obtain the second moving straight line; Calculate the first current tendency of the first moving line and the second current tendency of the second moving line respectively; Determine whether the first current tendency is less than or equal to the second current tendency. If so, based on the first tendency direction, move the second moving line according to the preset moving step size to obtain the third moving line. After multiple moves, when the Nth current tendency is greater than the (N-1)th current tendency, the (N-1)th moving line corresponding to the (N-1)th current tendency is taken as the target moving line. The coordinates of the intersection point of the target moving line and the vertical axis of the two-dimensional space of the current distribution are taken as the current trend value.

[0026] Optionally, the preset movement step size is determined based on the range of N current values ​​in the current dataset. For example, firstly, the difference between the maximum and minimum values ​​among the N current values ​​is calculated to obtain the range; then, the preset movement step size is set based on the constraint step size segmentation coefficient and the response correction coefficient. The step size segmentation coefficient refers to the proportion of the step size to the range; preferably, the step size segmentation coefficient is set to 0.05. The response correction coefficient is determined based on the response performance preference of the target inverter and is selected by a professional technician. If the target inverter requires a low response delay, the response correction coefficient is greater than 1, corresponding to a longer movement step size.

[0027] By using the above method to preset the moving step size, a larger moving step size is ensured for the first trend line that deviates significantly from the dense voltage value region, thus allowing for faster movement to the dense region.

[0028] Optionally, based on a preset moving step size, the first moving line is moved twice in the first moving direction to form a first moving line and a second moving line. The first moving line is the line formed after the first moving line moves once in the first moving direction, and the second moving line is the line formed after the first moving line moves twice in the first moving direction.

[0029] The first current tendency and the second current tendency are obtained by analyzing the density of coordinate points in the space where the first moving line and the second moving line are located. Then, by judging the magnitude of the first current tendency and the second current tendency, the positional superiority or inferiority of the first moving line and the second moving line can be identified.

[0030] Specifically, if the first current tendency is less than or equal to the second current tendency, the second moving line is moved along the first tendency direction according to the preset moving step size to obtain the third moving line. The position of the moving line is iteratively optimized until the Nth current tendency of the Nth moving line is greater than the N-1th current tendency of the Nth moving line. Then the N-1th moving line is set as the target moving line. Furthermore, the ordinate of the intersection point of the target's moving line and the vertical axis of the two-dimensional current distribution space is taken as the current trend value. This current trend value represents the value where the current value distribution is most dense in the two-dimensional current distribution space.

[0031] In some implementations, the first current tendency of the first moving line and the second current tendency of the second moving line are calculated respectively, and the method includes: The number of coordinate points in the two-dimensional space of the current distribution that are distanced from the first moving line to the preset moving step size is counted to generate the first current tendency. The number of coordinate points in the two-dimensional space of the current distribution that are distanced from the second moving line to the preset moving step size is counted to generate the second current tendency.

[0032] In other words, using a preset moving step size as the width of the statistical space and the first moving line as the center line of the statistical space, the neighborhood of the first moving line is obtained. Then, the number of coordinate points in the two-dimensional space of the current distribution located in the neighborhood of the first moving line is statistically analyzed and used as the first current tendency. The first current tendency reflects the number of coordinate points around the first moving line, indirectly reflecting the coordinate point density at the location of the first moving line.

[0033] Optionally, based on the same method and principle used to generate the first current tendency, a second current tendency is obtained. Similarly, the second current tendency reflects the number of coordinate points around the second moving line, indirectly reflecting the coordinate point density at the location of the second moving line. It should be understood that, for the sake of brevity, further explanation is not provided here.

[0034] Auxiliary fluctuation factors are obtained by performing fluctuation fitting on the vibration dataset and the monitored temperature dataset, respectively. In some embodiments, fluctuation fitting is performed on the vibration dataset and the monitored temperature dataset respectively to obtain an auxiliary fluctuation factor, the method comprising: The vibration gradients corresponding to multiple vibration data in the vibration dataset are calculated according to the time sequence. The multiple vibration gradients have multiple vibration gradient direction identifiers, which include positive and negative identifiers. Calculate multiple temperature gradients corresponding to multiple temperature data in the monitored temperature set according to the time sequence, wherein the multiple temperature gradients have multiple temperature gradient direction identifiers, including positive and negative identifiers; An auxiliary wave scatter plot is constructed based on the plurality of vibration gradients and the plurality of temperature gradients, as well as the plurality of vibration gradient direction identifiers and the plurality of temperature gradient identifiers; The auxiliary fluctuation factor is obtained by fitting the fluctuation based on the auxiliary fluctuation scatter plot.

[0035] Optionally, multiple vibration gradients corresponding to multiple vibration data points in the vibration dataset can be calculated according to the time series. The vibration gradient is obtained by calculating the rate of change of the vibration data, and each vibration gradient has a direction identifier, including a positive identifier indicating that the vibration data is increasing and a negative identifier indicating that the vibration data is decreasing.

[0036] Optionally, based on the same method principle used above to calculate multiple vibration gradients corresponding to multiple vibration data in the vibration dataset, multiple temperature gradients corresponding to multiple temperature data in the monitored temperature dataset are obtained. Furthermore, these multiple temperature gradients share the same directional identifier to reflect the direction of temperature change.

[0037] In some implementations, the method includes: The framework of the auxiliary fluctuation scatter plot is constructed with time as the horizontal axis and gradient as the vertical axis. The vibration gradients are added to the auxiliary wave scatter plot according to the multiple vibration gradient direction indicators to obtain multiple vibration gradient scatter points. The multiple temperature gradients are added to the auxiliary fluctuation scatter plot according to the multiple temperature gradient direction indicators to obtain multiple temperature gradient scatter points. The auxiliary fluctuation factor is obtained by comprehensively fitting the multiple vibration gradient scatter points and the multiple temperature gradient scatter points.

[0038] Optionally, an auxiliary fluctuation scatter plot is constructed based on multiple vibration gradients, multiple temperature gradients, multiple vibration gradient direction identifiers, and multiple temperature gradient identifiers. First, a scatter plot coordinate system is established with time as the horizontal axis and gradient as the vertical axis to form the framework of the auxiliary fluctuation scatter plot. Then, based on multiple vibration gradient direction identifiers, multiple vibration gradients are mapped to scatter points. Specifically, vibration gradients with positive vibration gradient direction identifiers are mapped above the horizontal axis, and vibration gradients with negative vibration gradient direction identifiers are mapped below the horizontal axis.

[0039] Optionally, multiple temperature gradient scatter points can be obtained based on the same acquisition method principle for multiple vibration gradient scatter points. It should be understood that, for the sake of brevity in the manual, no further explanation will be given here.

[0040] Furthermore, in some implementations, the auxiliary fluctuation factor is obtained by comprehensively fitting the plurality of vibration gradient scatter points and the plurality of temperature gradient scatter points, and the method includes: Linear regression is used to fit the multiple vibration gradient scatter points and the multiple temperature gradient scatter points to obtain a comprehensive fitting line. The slope of the composite fitted line is used as the auxiliary fluctuation factor.

[0041] Linear regression is a commonly used statistical method to study the relationship between two or more variables. By fitting linear regression to the scatter points of vibration gradient and temperature gradient, the resulting composite fitted line reflects the development trend of the vibration and temperature characteristics of the target frequency converter over time.

[0042] Furthermore, the larger the slope of the obtained composite fitted line, the faster the vibration and temperature characteristics of the target frequency converter develop over time, and the sign of the slope of the composite fitted line can reflect the direction of vibration and temperature changes. Therefore, the slope of the composite fitted line is used as an auxiliary fluctuation factor. This auxiliary fluctuation factor is used to assist in the overcurrent judgment of the target frequency converter.

[0043] Determine whether the current trend value is within the first-level warning bandwidth of the overload current threshold. If so, obtain the first warning instruction and trigger the overcurrent protection action according to the first warning instruction. Optionally, the overload current threshold is a current threshold set based on a dual threshold method, including an upper threshold and a lower threshold. For example, the lower threshold is the rated current of the target frequency converter, and the upper threshold is the maximum current of the target frequency converter.

[0044] Optionally, the space above the above threshold limit can be configured as the first-level warning bandwidth. If the current trend value is within the first-level warning bandwidth, it means that the real-time current of the target frequency converter has exceeded the maximum current of the target frequency converter, and a first warning command is generated for current protection.

[0045] Optionally, the first warning instruction is used to invoke higher-level current protection measures, such as: automatically reducing the operating current, disconnecting the power supply, and sending an alarm to the operator so that appropriate manual action can be taken.

[0046] If not, when the current trend value is within the secondary warning bandwidth of the overload current threshold, determine whether the auxiliary fluctuation factor meets the preset threshold. If so, obtain the second warning instruction and trigger the overcurrent protection action according to the second warning instruction.

[0047] Optionally, the space between the upper and lower thresholds can be configured as a secondary warning bandwidth. If the current trend value is within the secondary warning bandwidth, it indicates that the real-time current of the target inverter has exceeded the rated current of the target inverter, but is still lower than the maximum current of the target inverter, and further judgment is required.

[0048] Furthermore, it is determined whether the auxiliary fluctuation factor meets the preset threshold to assist in judging the status of the target frequency converter. The auxiliary fluctuation factor reflects the rate and direction of change of vibration and temperature of the target frequency converter. If the auxiliary fluctuation factor meets the preset threshold, it indicates that the vibration and temperature of the target frequency converter are deteriorating rapidly, and a second warning command is generated to activate the overcurrent protection action.

[0049] By monitoring the trend value of the current and the auxiliary fluctuation factor, the status of the target frequency converter can be determined more accurately, thereby preventing potential overcurrent conditions in advance. Furthermore, by setting different levels of warning bandwidth and thresholds, different protection measures can be taken according to the specific conditions of the target frequency converter and its environment, improving the adaptability and flexibility of overcurrent protection.

[0050] In summary, the adaptive inverter overcurrent protection method provided by this invention has the following technical effects: By interacting with the frequency converter, initial overcurrent protection parameters, including overload current threshold and overload delay window, are obtained; monitoring data of the frequency converter within the preset monitoring window, including current data, vibration data, and monitored temperature, are collected; the current state is analyzed based on the current data to obtain the current trend value; fluctuation fitting is performed on the vibration data and monitored temperature to obtain the auxiliary fluctuation factor; it is determined whether the current trend value is within the first-level warning bandwidth of the overload current threshold. If so, a first-level warning command is triggered; if not, and the current trend value is within the second-level warning bandwidth of the overload current threshold, it is determined whether the auxiliary fluctuation factor meets the preset threshold, and if so, a second-level warning command is triggered, thereby improving the threshold response flexibility and achieving rapid overcurrent protection response.

[0051] Example 2 Figure 2 This is a schematic diagram of the structure of an adaptive inverter overcurrent protection system according to the present invention. For example, Figure 1 The flowchart of an adaptive inverter overcurrent protection method of the present invention can be seen as follows: Figure 2 The structure shown is implemented.

[0052] Based on the same concept as the adaptive inverter overcurrent protection method in the above embodiment, the present invention also provides an adaptive inverter overcurrent protection system comprising: The protection parameter extraction module 11 is used to interact with the initial overcurrent protection parameters of the frequency converter, wherein the initial overcurrent protection parameters include an overload current threshold and an overload delay window; The monitoring and acquisition module 12 is used to acquire a set of monitoring data of the target frequency converter within a preset monitoring window, wherein the set of monitoring data includes a current dataset, a vibration dataset, and a monitoring temperature dataset. Trend analysis module 13 is used to perform current state analysis based on the current values ​​in the current dataset to obtain current trend values; The fluctuation fitting module 14 is used to perform fluctuation fitting on the vibration dataset and the monitored temperature dataset respectively to obtain an auxiliary fluctuation factor; The first-level early warning module 15 is used to determine whether the current trend value is within the first-level early warning bandwidth of the overload current threshold. If so, it obtains a first early warning instruction and triggers overcurrent protection action according to the first early warning instruction. The second early warning module 16 is used to determine whether the auxiliary fluctuation factor meets the preset threshold if the current trend value is within the secondary early warning bandwidth of the overload current threshold. If yes, it obtains a second early warning instruction and triggers overcurrent protection action according to the second early warning instruction.

[0053] The trend analysis module 13 includes: A current distribution unit is used to extract N current values ​​from the current dataset and construct a two-dimensional space for current distribution with time as the horizontal axis, current value as the vertical axis, and N current values ​​as N coordinate points. The mean line unit is used to take the straight line that passes through the mean of the N current values ​​and is parallel to the horizontal axis as the first trend line; A hierarchical division unit is used to divide the two-dimensional space of the current distribution into an upper space and a lower space using the first trending straight line; A trend determination unit is used to compare the number of coordinate points in the upper space and the lower space, and obtain a first trend direction based on the position of the space with more coordinate points relative to the first trend line. The first trend direction includes an upward movement indicator and a downward movement indicator. The trend value unit is used to perform current state analysis in the two-dimensional space of the current distribution based on the first trend direction and the first trend line to obtain the current trend value.

[0054] In some implementations, the trend value unit in the trend analysis module 13 includes: The first moving unit is used to move the first moving straight line according to the first moving direction and a preset moving step size to obtain the first moving straight line; The second moving unit is used to move the first moving line according to the preset moving step size based on the first directional direction to obtain the second moving line; The tendency calculation unit is used to calculate the first current tendency of the first moving line and the second current tendency of the second moving line, respectively. The tendency comparison unit is used to determine whether the first current tendency is less than or equal to the second current tendency. If so, the second moving line is moved according to the preset moving step size based on the first tendency direction to obtain the third moving line. The target moving line unit is used to take the (N-1)th moving line corresponding to the (N-1)th current tendency degree as the target moving line when the Nth current tendency degree is greater than the (N-1)th current tendency degree after multiple moves. The trend value acquisition unit is used to take the coordinate value of the intersection point of the target moving line and the vertical axis of the current distribution two-dimensional space as the current trend value.

[0055] In some implementations, the tendency value unit includes a tendency degree calculation unit: The first current tendency unit is used to count the number of coordinate points in the two-dimensional space of the current distribution whose distance from the first moving line is the preset moving step size, and generate the first current tendency. The second current tendency unit is used to count the number of coordinate points in the two-dimensional space of the current distribution whose distance from the second moving line is the preset moving step size, and generate the second current tendency.

[0056] The fluctuation fitting module 14 includes: The vibration gradient calculation unit is used to calculate multiple vibration gradients corresponding to multiple vibration data in the vibration dataset according to the time sequence. The multiple vibration gradients have multiple vibration gradient direction identifiers, including positive and negative identifiers. A temperature gradient calculation unit is used to calculate multiple temperature gradients corresponding to multiple temperature data in the monitored temperature set according to time sequence, wherein the multiple temperature gradients have multiple temperature gradient direction identifiers, including positive and negative identifiers. A scatter mapping unit is used to construct an auxiliary wave scatter plot based on the plurality of vibration gradients and the plurality of temperature gradients, as well as the plurality of vibration gradient direction identifiers and the plurality of temperature gradient identifiers. The fluctuation fitting unit is used to perform fluctuation fitting based on the auxiliary fluctuation scatter plot to obtain the auxiliary fluctuation factor.

[0057] In some implementations, the fluctuation fitting module 14 also includes: A framework building unit is used to construct the framework of the auxiliary fluctuation scatter plot with time as the horizontal axis and gradient as the vertical axis. A vibration gradient scatter mapping unit is used to add the multiple vibration gradients into the auxiliary wave scatter plot according to the multiple vibration gradient direction identifiers to obtain multiple vibration gradient scatter points. A temperature gradient scatter mapping unit is used to add the multiple temperature gradients into the auxiliary fluctuation scatter plot according to the multiple temperature gradient direction identifiers to obtain multiple temperature gradient scatter points. The comprehensive fitting unit is used to comprehensively fit the multiple vibration gradient scatter points and the multiple temperature gradient scatter points to obtain the auxiliary fluctuation factor.

[0058] In some implementations, the scatter mapping unit includes the following comprehensive fitting unit: The line fitting unit is used to perform line fitting on the multiple vibration gradient scatter points and the multiple temperature gradient scatter points using the linear regression method to obtain a comprehensive fitting line. The slope extraction unit is used to use the slope of the composite fitted line as the auxiliary fluctuation factor.

[0059] It should be understood that the focus of the embodiments mentioned in this specification is their difference from other embodiments. The specific embodiments in the aforementioned Embodiment 1 are also applicable to the adaptive inverter overcurrent protection system described in Embodiment 2. For the sake of brevity, they will not be elaborated further here.

[0060] It should be understood that the embodiments disclosed in this invention and the above description enable those skilled in the art to implement this invention. However, this invention is not limited to the embodiments mentioned above. It should be understood that those skilled in the art 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 spirit and scope of the technical solutions of the embodiments of this invention, and should all be included within the protection scope of this invention.

Claims

1. An adaptive overcurrent protection method for frequency converters, characterized in that, The method includes: The initial overcurrent protection parameters of the frequency converter are interactive, wherein the initial overcurrent protection parameters include an overload current threshold and an overload delay window; Collect a set of monitoring data of the target frequency converter within a preset monitoring window, wherein the set of monitoring data includes a current dataset, a vibration dataset, and a monitoring temperature dataset; Based on the current values ​​in the current dataset, current state analysis is performed to obtain current trend values; Auxiliary fluctuation factors are obtained by performing fluctuation fitting on the vibration dataset and the monitored temperature dataset, respectively. Determine whether the current trend value is within the first-level warning bandwidth of the overload current threshold. If so, obtain the first warning instruction and trigger the overcurrent protection action according to the first warning instruction. If not, when the current trend value is within the secondary warning bandwidth of the overload current threshold, determine whether the auxiliary fluctuation factor meets the preset threshold. If yes, obtain the second warning instruction and trigger the overcurrent protection action according to the second warning instruction. The method involves performing current state analysis based on the current values ​​in the current dataset to obtain current trend values, and includes: N current values ​​are extracted from the current dataset, and a two-dimensional space for current distribution is constructed with time as the horizontal axis, current value as the vertical axis, and N current values ​​as N coordinate points. The straight line that passes through the average of the N current values ​​and is parallel to the horizontal axis is taken as the first trend line. The two-dimensional space of the current distribution is divided into an upper space and a lower space using the first trend line. By comparing the number of coordinate points in the upper space and the lower space, and based on the position of the space with more coordinate points relative to the first trend line, the first trend direction is obtained, wherein the first trend direction includes an upward movement indicator and a downward movement indicator; Based on the first trend direction and the first trend line, current state analysis is performed in the two-dimensional space of the current distribution to obtain the current trend value; The method involves performing current state analysis within the two-dimensional space of the current distribution based on the first trend direction and the first trend line to obtain the current trend value. Based on the first trend direction, the first trend line is moved according to a preset moving step size to obtain the first moving line; Based on the first trend direction, the first moving straight line is moved according to the preset moving step size to obtain the second moving straight line; Calculate the first current tendency of the first moving line and the second current tendency of the second moving line respectively; Determine whether the first current tendency is less than or equal to the second current tendency. If so, based on the first tendency direction, move the second moving line according to the preset moving step size to obtain the third moving line. After multiple moves, when the Nth current tendency is greater than the (N-1)th current tendency, the (N-1)th moving line corresponding to the (N-1)th current tendency is taken as the target moving line. The coordinates of the intersection point of the target moving line and the vertical axis of the two-dimensional space of the current distribution are taken as the current trend value.

2. The method as described in claim 1, characterized in that, The method includes calculating the first current tendency of the first moving line and the second current tendency of the second moving line, respectively. The number of coordinate points in the two-dimensional space of the current distribution that are distanced from the first moving line to the preset moving step size is counted to generate the first current tendency. The number of coordinate points in the two-dimensional space of the current distribution that are distanced from the second moving line to the preset moving step size is counted to generate the second current tendency.

3. The method as described in claim 1, characterized in that, The method involves performing fluctuation fitting on the vibration dataset and the monitored temperature dataset respectively to obtain an auxiliary fluctuation factor, the method comprising: The vibration gradients corresponding to multiple vibration data in the vibration dataset are calculated according to the time sequence. The multiple vibration gradients have multiple vibration gradient direction identifiers, including positive and negative identifiers. Calculate multiple temperature gradients corresponding to multiple temperature data in the monitored temperature set according to the time sequence, wherein the multiple temperature gradients have multiple temperature gradient direction identifiers, including positive and negative identifiers; An auxiliary wave scatter plot is constructed based on the plurality of vibration gradients and the plurality of temperature gradients, as well as the plurality of vibration gradient direction identifiers and the plurality of temperature gradient identifiers; The auxiliary fluctuation factor is obtained by fitting the fluctuation based on the auxiliary fluctuation scatter plot.

4. The method as described in claim 3, characterized in that, The method includes: The framework of the auxiliary fluctuation scatter plot is constructed with time as the horizontal axis and gradient as the vertical axis. The vibration gradients are added to the auxiliary wave scatter plot according to the multiple vibration gradient direction indicators to obtain multiple vibration gradient scatter points. The multiple temperature gradients are added to the auxiliary fluctuation scatter plot according to the multiple temperature gradient direction indicators to obtain multiple temperature gradient scatter points. The auxiliary fluctuation factor is obtained by comprehensively fitting the multiple vibration gradient scatter points and the multiple temperature gradient scatter points.

5. The method as described in claim 4, characterized in that, The auxiliary fluctuation factor is obtained by comprehensively fitting the multiple vibration gradient scatter points and the multiple temperature gradient scatter points. The method includes: Linear regression is used to fit the multiple vibration gradient scatter points and the multiple temperature gradient scatter points to obtain a comprehensive fitting line. The slope of the composite fitted line is used as the auxiliary fluctuation factor.

6. An adaptive overcurrent protection system for a frequency converter, characterized in that, The system includes: The protection parameter extraction module is used to interact with the initial overcurrent protection parameters of the frequency converter, wherein the initial overcurrent protection parameters include an overload current threshold and an overload delay window; The monitoring and acquisition module is used to acquire a set of monitoring data of the target frequency converter within a preset monitoring window, wherein the set of monitoring data includes a current dataset, a vibration dataset, and a monitoring temperature dataset. A trend analysis module is used to perform current state analysis based on the current values ​​in the current dataset to obtain current trend values. A fluctuation fitting module is used to perform fluctuation fitting on the vibration dataset and the monitored temperature dataset respectively to obtain an auxiliary fluctuation factor. A first-level early warning module is used to determine whether the current trend value is within the first-level early warning bandwidth of the overload current threshold. If so, a first early warning instruction is obtained, and an overcurrent protection action is triggered according to the first early warning instruction. The second early warning module is used to determine whether the auxiliary fluctuation factor meets the preset threshold when the current trend value is within the secondary early warning bandwidth of the overload current threshold. If yes, a second early warning instruction is obtained, and overcurrent protection action is triggered according to the second early warning instruction. The trend analysis module includes: A current distribution unit is used to extract N current values ​​from the current dataset and construct a two-dimensional space for current distribution with time as the horizontal axis, current value as the vertical axis, and N current values ​​as N coordinate points. The mean line unit is used to take the straight line that passes through the mean of the N current values ​​and is parallel to the horizontal axis as the first trend line; A hierarchical division unit is used to divide the two-dimensional space of the current distribution into an upper space and a lower space using the first trending straight line; A trend determination unit is used to compare the number of coordinate points in the upper space and the lower space, and obtain a first trend direction based on the position of the space with more coordinate points relative to the first trend line. The first trend direction includes an upward movement indicator and a downward movement indicator. The trend value unit is used to perform current state analysis in the two-dimensional space of the current distribution based on the first trend direction and the first trend line to obtain the current trend value. The trend analysis module includes the following trend value units: The first moving unit is used to move the first moving straight line according to the first moving direction and a preset moving step size to obtain the first moving straight line; The second moving unit is used to move the first moving line according to the preset moving step size based on the first directional direction to obtain the second moving line; The tendency calculation unit is used to calculate the first current tendency of the first moving line and the second current tendency of the second moving line, respectively. The tendency comparison unit is used to determine whether the first current tendency is less than or equal to the second current tendency. If so, the second moving line is moved according to the preset moving step size based on the first tendency direction to obtain the third moving line. The target moving line unit is used to take the (N-1)th moving line corresponding to the (N-1)th current tendency degree as the target moving line when the Nth current tendency degree is greater than the (N-1)th current tendency degree after multiple moves. The trend value acquisition unit is used to take the coordinate value of the intersection point of the target moving line and the vertical axis of the current distribution two-dimensional space as the current trend value.

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