Power transformer capacity detection method and system

Abstract

The invention discloses a power transformer capacity detection method and system, and relates to the technical field of electrical performance measurement. The power transformer capacity detection method comprises the following steps: acquiring a current minimum load value and a current maximum load value; obtaining first detection data and second detection data based on the current minimum load value and the current maximum load value; obtaining a first approximation degree and a second approximation degree based on the first detection data and the second detection data; obtaining a target load value based on the first approximation degree and the second approximation degree; and updating the current minimum load value and the current maximum load value based on the target load value. According to the method, the target load value is intelligently selected in an iteration mode, and the test load range can be quickly narrowed under the condition that the test load range is relatively large. And the maximum apparent power of the power transformer can be quickly found under the condition that the test load range is relatively small.

Description

Technical Field

[0001] This application relates to the technical field of electrical performance measurement, and particularly to a method and system for detecting the capacity of a power transformer. Background Art

[0002] A power transformer is a key device used for power transmission and distribution. Its main function is to transfer energy between the primary coil and the secondary coil through the principle of electromagnetic induction, thereby adjusting the voltage magnitude, converting AC voltages of different voltage levels in the power system into suitable voltages, and ensuring that electricity can be safely and effectively transmitted to the end users. The rated capacity of a power transformer represents its maximum load capacity. Detecting the rated capacity of the transformer can ensure its operation within a reasonable load range, thereby enhancing the overall safety of the power system.

[0003] The prior art generally uses the load method to measure the rated capacity of a power transformer. Starting from zero load, the load is gradually increased. By applying different loads multiple times and comparing the apparent power values under each load, the rated capacity of the transformer is finally confirmed. Under the stable operation state, the maximum measured apparent power is the rated capacity of the transformer. It should be noted that during the process of measuring the rated capacity of a power transformer using the load method, if the load increment is set too large, some key load states may be missed, resulting in the inability to accurately find the rated capacity of the transformer. If the load increment is set too small, since after each adjustment of the load, it is necessary to ensure that the power transformer reaches a stable state and lasts for a period of time at each load state before accurately measuring the apparent power, the test cycle is extremely long. Summary of the Invention

[0004] The purpose of this application is to provide a method and system for detecting the capacity of a power transformer to solve the technical problem that the prior art cannot accurately select the load increment.

[0005] To achieve the above purpose, this application provides the following technical solutions: In the first aspect, this application proposes a technical solution for a method for detecting the capacity of a power transformer. The method for detecting the capacity of a power transformer includes: Obtain the current minimum load value and the current maximum load value; the load value at least includes the power value output during the operation of the power transformer; the current minimum load value and the current maximum load value are updated from the historical minimum load value and the historical maximum load value; Based on the current minimum load value and the current maximum load value, first detection data and second detection data are obtained; the first detection data is the detection data corresponding to the power transformer when it is at the current minimum load value; the second detection data is the detection data corresponding to the power transformer when it is at the current maximum load value; the detection data at least includes the current value, voltage value, and apparent power value of the power transformer; Based on the first detection data and the second detection data, a first approximation degree and a second approximation degree are obtained; the first approximation degree is at least used to characterize the magnitude of the difference between the target load value and the current minimum load value; the second approximation degree is at least used to characterize the magnitude of the difference between the target load value and the current maximum load value; Based on the first approximation degree and the second approximation degree, a target load value is obtained; Based on the target load value, the current minimum load value and the current maximum load value are updated; Detection is performed based on the updated current minimum load value and current maximum load value, and then the capacity of the power transformer is obtained.

[0006] As a specific solution in the technical solution of this application, before obtaining the first approximation degree and the second approximation degree based on the first detection data and the second detection data, the method further includes: Based on the detection data, a validity value is obtained; the validity value is at least used to characterize the magnitude of the validity of the apparent power value in the detection data; the detection data includes the first detection data and the second detection data.

[0007] As a specific solution in the technical solution of this application, obtaining the validity value based on the detection data includes: Based on the detection data, a root-mean-square voltage value is obtained; the root-mean-square voltage value is at least used to characterize the magnitude of the fluctuation difference between the input voltage and the output voltage during the detection of the power transformer; Based on the detection data, a root-mean-square current value is obtained; the root-mean-square current value is at least used to characterize the magnitude of the difference between the output current and the theoretical output current during the detection of the power transformer; Based on the root-mean-square voltage value and the root-mean-square current value, the validity value is obtained.

[0008] As a specific solution in the technical solution of this application, the calculation formula for obtaining the root-mean-square voltage value based on the detection data is as follows:

[0009] Wherein, represents the root-mean-square voltage value; n represents the number of voltage values included in the detection data; represents the turns ratio of the primary coil to the secondary coil in the power transformer; represents the i-th input voltage in the detection data; represents the i-th output voltage in the detection data; represents taking the absolute value; is a constant, and is greater than 0 and less than or equal to 1; Based on the detection data, the calculation formula for obtaining the effective current value is as follows:

[0010] wherein, represents the effective current value; n represents the number of current values included in the detection data; exp represents the exponential function with base e; represents the i-th input current in the detection data; represents the theoretical output current of the power transformer under the current load; represents the effective voltage value; Based on the effective voltage value and the effective current value, the calculation formula for obtaining the effectiveness value is as follows:

[0011] wherein, Y represents the effectiveness value; represents the effective voltage value; represents the average value of the output voltage after a preset time in the detection data under the current load; represents the effective current value; represents the average value of the output current after a preset time in the detection data under the current load; the preset time is greater than or equal to 10 minutes.

[0012] As a specific solution in the technical solution of this application, the obtaining of the first approximation degree and the second approximation degree based on the first detection data and the second detection data includes: Obtaining an instability value based on the first detection data and the second detection data; the instability value is at least used to characterize the magnitude of the volatility difference of the voltage and / or current in the first detection data and the second detection data; Obtaining an overload value based on the instability value; the overload value is at least used to characterize the magnitude of the possibility of power transformer overload in the first detection data and the second detection data; Obtaining the first approximation degree and the second approximation degree based on the overload value.

[0013] As a specific solution in the technical solution of this application, the calculation formula for obtaining the instability value based on the first detection data and the second detection data is as follows:

[0014] wherein, represents the instability value corresponding to the voltage; n represents the number of voltage values included in the detection data, and n is greater than or equal to 5; represents that the normalization function is used to map the value within the brackets to the range of [0, 1]; represents the i-th input voltage in the first detection data, where i is greater than or equal to 1 and less than or equal to n; represents the j-th input voltage in the first detection data, where j is greater than or equal to 1, and i is greater than or equal to i - 2 and less than or equal to i + 2; represents the i-th input voltage in the second detection data; represents the j-th input voltage in the second detection data; represents taking the absolute value.

[0015] As a specific solution in the technical solution of the present application, the calculation formula for obtaining the overload value based on the instability value is as follows:

[0016] wherein, represents the overload value; represents the effective value of the voltage corresponding to the first detection data; represents the effective value of the voltage corresponding to the second detection data; represents the instability value corresponding to the voltage; represents the effective value of the current corresponding to the first detection data; represents the effective value of the current corresponding to the second detection data; represents the instability value corresponding to the current.

[0017] As a specific solution in the technical solution of the present application, the calculation formula for obtaining the first approximation degree based on the overload value is as follows:

[0018] wherein, represents the first approximation degree; represents the overload value; represents the effectiveness value corresponding to the first detection data; The calculation formula for obtaining the second approximation degree based on the overload value is as follows:

[0019] wherein, represents the second approximation degree; represents the overload value; Represents the validity value corresponding to the second detection data.

[0020] As a specific solution in the technical solution of this application, the calculation formula for obtaining the target load value based on the first approximation degree and the second approximation degree is as follows:

[0021] Wherein, Represents the target load value; Represents the first approximation degree; Represents the second approximation degree; Represents the current minimum load value; Represents the current maximum load value.

[0022] In a second aspect, this application proposes a technical solution for a power transformer capacity detection system. The power transformer capacity detection system includes: An acquirer for acquiring the current minimum load value and the current maximum load value; A controller for obtaining first detection data and second detection data based on the current minimum load value and the current maximum load value; the first detection data is the detection data corresponding to the power transformer when it is at the current minimum load value; the second detection data is the detection data corresponding to the power transformer when it is at the current maximum load value; the detection data at least includes the current value, voltage value, and apparent power value of the power transformer; A processor for obtaining a first approximation degree and a second approximation degree based on the first detection data and the second detection data; the first approximation degree is at least used to characterize the difference between the target load value and the current minimum load value; the second approximation degree is at least used to characterize the difference between the target load value and the current maximum load value; And obtaining the target load value based on the first approximation degree and the second approximation degree; And updating the current minimum load value and the current maximum load value based on the target load value; The controller is further configured to perform detection based on the updated current minimum load value and current maximum load value, and then obtain the capacity of the power transformer.

[0023] As a specific solution in the technical solution of this application, the processor is further configured to obtain a validity value based on the detection data; the validity value is at least used to characterize the validity of the apparent power value in the detection data; the detection data includes the first detection data and the second detection data.

[0024] As a specific solution in the technical solution of the present application, the processor is further configured to obtain the effective voltage value based on the detection data; the effective voltage value is at least used to characterize the magnitude of the fluctuation difference between the input voltage and the output voltage during the detection of the power transformer; and, obtain the effective current value based on the detection data; the effective current value is at least used to characterize the magnitude of the difference between the output current and the theoretical output current during the detection of the power transformer; and, obtain the effectiveness value based on the effective voltage value and the effective current value.

[0025] As a specific solution in the technical solution of the present application, the calculation formula for the processor to obtain the effective voltage value based on the detection data is as follows:

[0026] where, represents the effective voltage value; n represents the number of voltage values included in the detection data; represents the turns ratio of the primary coil to the secondary coil in the power transformer; represents the i-th input voltage in the detection data; represents the i-th output voltage in the detection data; represents taking the absolute value; is a constant, and is greater than 0 and less than or equal to 1; The calculation formula for the processor to obtain the effective current value based on the detection data is as follows:

[0027] where, represents the effective current value; n represents the number of current values included in the detection data; exp represents the exponential function with the natural constant e as the base; represents the i-th input current in the detection data; represents the theoretical output current of the power transformer under the current load; represents the effective voltage value; The calculation formula for the processor to obtain the effectiveness value based on the effective voltage value and the effective current value is as follows:

[0028] where Y represents the effectiveness value; represents the effective voltage value; represents the average value of the output voltage after a preset time in the detection data under the current load; represents the effective current value; It represents the average value of the output current in the detected data after a preset time under the current load; the preset time is greater than or equal to 10 minutes.

[0029] As a specific solution in the technical solution of the present application, the processor is further configured to obtain an instability value based on the first detected data and the second detected data; the instability value is at least used to characterize the magnitude of the fluctuation difference of the voltage and / or current in the first detected data and the second detected data; And, based on the instability value, obtain an overload value; the overload value is at least used to characterize the magnitude of the possibility of power transformer overload in the first detected data and the second detected data; And, based on the overload value, obtain the first approximation degree and the second approximation degree.

[0030] As a specific solution in the technical solution of the present application, the calculation formula for the processor to obtain the instability value based on the first detected data and the second detected data is as follows:

[0031] Where, represents the instability value corresponding to the voltage; n represents the number of voltage values included in the detected data, and n is greater than or equal to 5; represents that the normalization function is used to map the value within the parentheses to the range of [0, 1]; represents the i-th input voltage in the first detected data, where i is greater than or equal to 1 and less than or equal to n; represents the j-th input voltage in the first detected data, where j is greater than or equal to 1, and i is greater than or equal to i - 2 and less than or equal to i + 2; represents the i-th input voltage in the second detected data; represents the j-th input voltage in the second detected data; represents taking the absolute value.

[0032] As a specific solution in the technical solution of the present application, the calculation formula for the processor to obtain the overload value based on the instability value is as follows:

[0033] Where, represents the overload value; represents the effective value of the voltage corresponding to the first detected data; represents the effective value of the voltage corresponding to the second detected data; represents the instability value corresponding to the voltage; represents the effective value of the current corresponding to the first detected data; Represents the effective current value corresponding to the second detection data; Represents the instability value corresponding to the current.

[0034] As a specific solution in the technical solution of the present application, the processor obtains the calculation formula of the first approximation degree based on the overload value as follows:

[0035] Wherein, Represents the first approximation degree; Represents the overload value; Represents the validity value corresponding to the first detection data; The processor obtains the calculation formula of the second approximation degree based on the overload value as follows:

[0036] Wherein, Represents the second approximation degree; Represents the overload value; Represents the validity value corresponding to the second detection data.

[0037] As a specific solution in the technical solution of the present application, the processor obtains the calculation formula of the target load value based on the first approximation degree and the second approximation degree as follows:

[0038] Wherein, Represents the target load value; Represents the first approximation degree; Represents the second approximation degree; Represents the current minimum load value; Represents the current maximum load value.

[0039] Compared with the prior art, the beneficial effects of the present application are: Compared with the prior art that tests the rated capacity of a power transformer by gradually increasing the load, the present application intelligently selects the target load value through an iterative method. In the case of a large test load range, it can quickly narrow the test load range. In the case of a small test load range, it can quickly find the maximum apparent power of the power transformer. It not only improves the test accuracy but also significantly improves the test efficiency, shortens the test time, and ensures a faster and more reliable acquisition of the rated capacity of the power transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Is a schematic flowchart of a method for detecting the capacity of a power transformer proposed in an embodiment of the present application; Figure 2 The structural schematic diagram of a power transformer capacity detection system proposed by an embodiment of the present application. Specific implementation manners

[0041] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0042] The terms "first", "second", etc. in the specification of the embodiments of the present application and the above accompanying drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. For example, the first approximation degree and the second approximation degree proposed below belong to different approximation degrees. It should be understood that such names can be interchanged under appropriate circumstances so that the embodiments described here can be implemented in an order other than that illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or modules does not have to be limited to those steps or modules clearly listed, but may include other steps or modules not clearly listed or inherent to these processes, methods, products, or devices. The division of modules in the embodiments of the present application is only a logical division. In actual implementation, there may be other division methods. For example, multiple modules can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed couplings, direct couplings, or communication connections to each other may be through some interfaces. The indirect couplings or communication connections between modules may be electrical or other similar forms, which are not limited in the embodiments of the present application. And the modules or sub-modules described as separate components may or may not be physically separated, may or may not be physical modules, or may be distributed to multiple circuit modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the embodiments of the present application.

[0043] In order to solve the technical problem that when using the load method to detect the capacity of a power transformer in the background technology, the load increment cannot be accurately set, that is, the target load value in the following text cannot be accurately found, the present application proposes a power transformer capacity detection method, as Figure 1 shown, the power transformer capacity detection method includes steps S100 to S600.

[0044] Step S100: Obtain the current minimum load value and the current maximum load value.

[0045] It should be clear that the load value at least includes the power value output when the power transformer is operating. The current minimum load value and the current maximum load value are updated from the historical minimum load value and the historical maximum load value. In this embodiment, the initial minimum load value and the maximum load value can be set manually according to the model of the power transformer.

[0046] Step S200: Based on the current minimum load value and the current maximum load value, obtain the first detection data and the second detection data.

[0047] In this embodiment, the first detection data is the detection data corresponding to the power transformer when it is at the current minimum load value. The second detection data is the detection data corresponding to the power transformer when it is at the current maximum load value. The detection data at least includes the current value, voltage value and apparent power value of the power transformer.

[0048] It should be noted that for a power transformer, it is known that the turns ratio of its primary coil to its secondary coil is z, and the range of the load it can withstand is (i.e., the minimum load value) to (i.e., the maximum load value). The steps to obtain its detection data are as follows: First, connect a minimum load to the secondary coil of the power transformer using an adjustable resistor load box , and ensure that the load is stable. Then, connect a voltage sensor to the primary coil of the transformer and record the data of the input voltage changing with time for 10 minutes (a mature technology, not elaborated). Then connect the voltage sensor to the secondary coil of the transformer and record the data of the output voltage changing with time for 10 minutes. At the same time, connect a current sensor to the secondary coil of the transformer and record the data of the output current changing with time for 10 minutes. Of course, in other embodiments of the present application, the current and voltage data of other appropriate time lengths can be recorded as the detection data, for example: the recording duration can also be 8 minutes or 12 minutes, etc. After connecting the minimum load and operating stably, wait for 10 minutes and record the instantaneous output voltage value and the output current value . Then, use the product of these two instantaneous values to calculate the apparent power in the case of the minimum load.

[0049] Following the same operation as above, the input voltage and input current data of the power transformer within 10 minutes when the maximum load is connected to the secondary coil can be obtained. Similarly, after connecting the maximum load and operating stably, wait for 10 minutes and record the instantaneous output voltage value and the output current value 。Then, the product of these two instantaneous values is used to calculate the apparent power under the maximum load condition. Thus, the introduction of obtaining the first detection data and the second detection data based on the current minimum load value and the current maximum load value is completed.

[0050] It should be noted that in the following text of this embodiment, the capacity of the power transformer can be directly detected based on steps S300 to S600. The power transformer works based on the principle of electromagnetic induction. Specifically, the power transformer consists of two windings (primary coil and secondary coil) and a magnetic core. When current passes through the primary coil, a changing magnetic field is generated, and this changing magnetic field then induces a voltage in the secondary coil. According to Faraday's law of electromagnetic induction, the magnitude of the induced voltage is proportional to the rate of change of the magnetic field (i.e., the rate of change of current). And the rate of change of the magnetic field is directly related to the number of turns of the coil. If the number of turns is more, the induced voltage is also larger. Therefore, for each moment, the smaller the difference between the input voltage and the output voltage multiplied by the turns ratio, the more the output voltage can effectively reflect the true and effective voltage of the power transformer working. However, the influence of effectiveness is not the same at different time points. Since the magnetic field of the transformer is generated by the input current, when the power supply is connected, the current in the primary coil increases and gradually builds the magnetic field. The change of the magnetic field takes a certain amount of time, so the changes of the input voltage and current are not instantaneous. The transition process of the transformer from the static state to the stable working state takes a certain amount of time. Therefore, as time goes by, especially at later moments, the influence on the effectiveness of the instantaneous voltage collected after 10 minutes will be more significant. That is to say, in this embodiment, the effectiveness of the obtained apparent power value also needs to be considered. Without considering the effectiveness of the apparent power value, if the effectiveness of the apparent power value in the obtained test data is lower, the accuracy of the capacity of the power transformer obtained based on this test data is also poorer. Based on this, before step S300 of obtaining the first approximation degree and the second approximation degree based on the first detection data and the second detection data, the method further includes step S700.

[0051] Step S700: Obtain an effectiveness value based on the detection data.

[0052] In this embodiment, the effectiveness value is at least used to characterize the effectiveness magnitude of the apparent power value in the detection data. The detection data includes the first detection data and the second detection data. That is to say, in this application, the effectiveness value of the first detection data or the second detection data can refer to step S700. In this embodiment, any reasonable method can be adopted to obtain the effectiveness value based on the detection data. For example: Step S700 of obtaining an effectiveness value based on the detection data includes steps S710 to S730.

[0053] Step S710: Obtain the effective voltage value based on the detection data.

[0054] In this embodiment, the effective voltage value is at least used to characterize the magnitude of the fluctuation difference between the input voltage and the output voltage during the detection of the power transformer. In this embodiment, any suitable index can be used as the effective voltage value to characterize the magnitude of the fluctuation difference between the input voltage and the output voltage during the detection of the power transformer. For example, the difference between the variance of the input voltage and the variance of the output voltage can be used as the effective voltage value.

[0055] In a specific embodiment of the present application, in step S710, the calculation formula for obtaining the effective voltage value based on the detection data is as follows:

[0056] Wherein, represents the effective voltage value; n represents the number of voltage values included in the detection data; represents the turns ratio of the primary coil to the secondary coil in the power transformer; represents the i-th input voltage in the detection data; represents the i-th output voltage in the detection data; represents taking the absolute value; is a constant, and is greater than 0 and less than or equal to 1.

[0057] Step S720: Obtain the effective current value based on the detection data.

[0058] In this embodiment, the effective current value is at least used to characterize the magnitude of the difference between the output current and the theoretical output current during the detection of the power transformer. In this embodiment, any suitable index can be used as the effective current value to characterize the magnitude of the difference between the output current and the theoretical output current during the detection of the power transformer. For example, the effective current value can be the difference between the average value of the output current and the theoretical output current.

[0059] In the operation of a power transformer, when the load is fixed, based on Ohm's law and the basic principle of power transmission, the magnitude of the output current is mainly determined by the output voltage, and the output current is equal to the output voltage divided by the load value. Therefore, the effectiveness of the output current first depends on the effectiveness of the output voltage. At the same time, on this basis, the true output current at any moment should be equal to the ideal current value calculated according to Ohm's law to be truly effective. And as can be seen from the above, the transition process of the transformer from the stationary state to the stable operating state takes a certain amount of time. Therefore, as time goes by, especially at later moments, the impact on the effectiveness of the instantaneous current collected 10 minutes later will be more significant. Based on this, in a specific embodiment of the present application, in step S720, based on the detection data, the calculation formula for the effective value of the current is as follows:

[0060] Wherein, represents the effective value of the current; n represents the number of current values included in the detection data; exp represents the exponential function with the natural constant e as the base; represents the i-th input current in the detection data; represents the theoretical output current of the power transformer under the current load; represents the effective value of the voltage.

[0061] Step S730: Based on the effective value of the voltage and the effective value of the current, obtain the effectiveness value.

[0062] It should be clear that in this embodiment, the effectiveness value can be obtained based on the effective value of the voltage and the effective value of the current in any reasonable manner. For example, the sum or product of the effective value of the voltage and the effective value of the current is used as the effectiveness value.

[0063] It should be noted that in a power transformer, the apparent power under the maximum load is calculated by the product of the instantaneous output current and the output voltage 10 minutes later. Therefore, the effectiveness of the apparent power is the result of the combined action of the voltage and the current. To improve the effectiveness of the apparent power, it is necessary to ensure that both the output voltage and the current have high effectiveness at their respective higher levels. This means that when the voltage is high, the voltage should be ensured to be effective, and when the current is large, the current should be ensured to be effective. Based on this, in step S730, the calculation formula for obtaining the effectiveness value based on the effective value of the voltage and the effective value of the current is as follows:

[0064] Wherein, Y represents the effectiveness value; represents the effective value of the voltage; represents the average value of the output voltage after a preset time in the detection data under the current load; represents the effective value of current; represents the average value of the output current after a preset time in the detection data under the current load; the preset time is greater than or equal to 10 minutes.

[0065] Step S300: Based on the first detection data and the second detection data, obtain a first approximation degree and a second approximation degree.

[0066] In this embodiment, the first approximation degree is at least used to characterize the difference between the target load value and the current minimum load value, and the second approximation degree is at least used to characterize the difference between the target load value and the current maximum load value. In this embodiment, the target load value is calculated through the first approximation degree and the second approximation degree, so as to update the current minimum load value or the current maximum load value with the target load value, and then quickly test the capacity of the power transformer.

[0067] It should be clear that in this embodiment, the first approximation degree and the second approximation degree can be directly obtained based on the first detection data and the second detection data by using the bisection method. That is to say, the gap between the target load value and the current minimum load value is equal to the gap between the target load value and the current maximum load value.

[0068] It should be noted that the first approximation degree and the second approximation degree obtained based on the bisection method are not accurate. The smaller the volatility gap between the first detection data and the second detection data, the closer the current minimum load value and the current maximum load value are to the capacity of the power transformer. At this time, when selecting the target load value, the intermediate value of the current minimum load value and the current maximum load value can be selected. The larger the volatility gap between the first detection data and the second detection data, the farther the current minimum load value is from the capacity of the power transformer. At this time, when selecting the target load value, the target load value can be made closer to the current maximum load value, thereby narrowing the range between the updated current minimum load value and the current maximum load value, that is, facilitating the subsequent rapid search for the capacity of the power transformer. For example: if the volatility difference between the first detection data and the second detection data is small, the target load value should be close to the intermediate value between the current minimum load value and the current maximum load value; if the volatility difference between the first detection data and the second detection data is large, the target load value should be close to the current maximum load value. Based on this, step S300, based on the first detection data and the second detection data, obtain a first approximation degree and a second approximation degree, including steps S310 to S330.

[0069] Step S310: Based on the first detection data and the second detection data, obtain an instability value.

[0070] In this embodiment, the instability value is at least used to characterize the magnitude of the fluctuation difference in voltage and / or current between the first detection data and the second detection data. It should be clear that the instability value can be obtained based on the first detection data and the second detection data in any reasonable manner. For example, the standard deviation of the voltage in the first detection data and the standard deviation of the voltage in the second detection data can be calculated, and the difference between the two standard deviations can be used as the instability value.

[0071] It should be noted that in order to determine the instability of voltage and current when the power transformer is at the current maximum load compared to the minimum load, the relative instability of voltage and current needs to be evaluated at multiple moments. Taking voltage as an example, the output voltage time series data of n are measured under both the maximum load and the minimum load. For each time series data, if there is a large difference between the measured value of an output voltage and the measured values of several adjacent (5 in the following embodiments, which can be 4 or 7 in other embodiments of the present application, that is, there is no limit on the number of data participating in the calculation) output voltages, then it can be considered that the volatility of this output voltage is relatively high. Further, in the same time series, if the volatility of the output voltage under the maximum load is significantly greater than the volatility of the output voltage under the minimum load, then we can judge that the instability of the output voltage under the maximum load relative to the output voltage under the minimum load is relatively high. Based on this, in a specific embodiment of the present application, in step S310, the calculation formula for obtaining the instability value based on the first detection data and the second detection data is as follows:

[0072] Wherein, represents the instability value corresponding to the voltage; n represents the number of voltage values included in the detection data, and n is greater than or equal to 5; represents the normalization function for mapping the value within the parentheses to the range of [0, 1]; represents the i-th input voltage in the first detection data, where i is greater than or equal to 1 and less than or equal to n; represents the j-th input voltage in the first detection data, where j is greater than or equal to 1, and i is greater than or equal to i - 2 and less than or equal to i + 2; represents the i-th input voltage in the second detection data; represents the j-th input voltage in the second detection data; represents taking the absolute value.

[0073] It should be noted that in the embodiments of the present application, the instability value corresponding to the current can also be calculated according to the above formula, only by replacing the voltage value in the above formula with the current value, which will not be elaborated here.

[0074] Step S320: Obtain an overload value based on the instability value.

[0075] In this embodiment, the overload value is at least used to characterize the likelihood of overload of the power transformer in the first detection data and the second detection data. If the detection data indicates that the power transformer is overloaded, it means that the load value corresponding to the detection data is close to the capacity of the power transformer. That is to say, the overload value can be used to quickly locate whether it is close to the capacity of the power transformer.

[0076] It should be noted that for a power transformer, under normal load, the magnetic core of the transformer operates within the designed magnetic flux density range, and at this time, the output voltage and current of the transformer are relatively stable. However, in the case of overload, the load current exceeds the design capacity of the transformer, resulting in the magnetic core possibly entering the saturation state. When the magnetic core is saturated, the inductance value of the transformer decreases, thereby exacerbating the volatility of the current and voltage, manifested as an increase in the instability of the voltage and current. That is to say, when calculating the overload of the maximum load compared to the minimum load, if the voltage and current are relatively true and effective under the maximum load condition, and at the same time the instability also increases significantly, then it can be considered that the maximum load has a higher overload compared to the minimum load.

[0077] In the embodiment of the present application, any reasonable method can be adopted to obtain the overload value based on the instability value. For example, directly use the instability value as the overload value. In a specific embodiment of the present application, in step S320, the calculation formula for obtaining the overload value based on the instability value is as follows:

[0078] Wherein, represents the overload value; represents the effective voltage value corresponding to the first detection data; represents the effective voltage value corresponding to the second detection data; represents the instability value corresponding to the voltage; represents the effective current value corresponding to the first detection data; represents the effective current value corresponding to the second detection data; represents the instability value corresponding to the current.

[0079] Step S330: Obtain the first approximation degree and the second approximation degree based on the overload value.

[0080] As can be seen from the foregoing, if the overload value is larger, it indicates that the current minimum load value is farther from the capacity value of the power transformer. At this time, the selected target load value should be close to the current maximum load value. If the overload value is smaller, it means that the capacity of the power transformer is equivalent to the positions of the current minimum load value and the current maximum load value. At this time, the selected target load value should be equivalent to the distances from the current minimum load value and the current maximum load value.

[0081] It should be noted that generally when determining the target load value, any load value between the current minimum load value and the current maximum load value is selected as the target load value. However, as can be seen from step S700, the apparent power corresponding to the maximum load and the minimum load does not necessarily represent the true effective power. To ensure that the target load value has more practical significance, a load with higher effectiveness obtained in step S700 should be selected. In other words, the target load value should approach the load value with higher effectiveness among the current maximum load value and the current minimum load value. However, within the current load range, as the load increases, the power value may show two different trends. If the overload of the maximum load is relatively high, then even if the power value of the power transformer is relatively large compared to the minimum load at this time, a value closer to the minimum load value should still be selected as the target load value to ensure that the maximum power always remains within the range corresponding to the current maximum load value and the minimum load value, thereby ensuring the accuracy of the measurement. Based on this, in step S330, based on the overload value, the calculation formula for obtaining the first approximation degree is as follows:

[0082] where, represents the first approximation degree; represents the overload value; represents the effectiveness value corresponding to the first detection data; In step S330, based on the overload value, the calculation formula for obtaining the second approximation degree is as follows:

[0083] where, represents the second approximation degree; represents the overload value; represents the effectiveness value corresponding to the second detection data.

[0084] Step S400: Based on the first approximation degree and the second approximation degree, obtain the target load value.

[0085] It should be clear that in step S330, the approximation degree of the target load value relative to the current maximum load value and the minimum load value has been determined. If the relative approximation degree of the target load value to the minimum load value is high, then the target load value should be close to the minimum load value; conversely, if the relative approximation degree of the target load value to the maximum load value is high, then the target load value should be close to the maximum load value. Based on this, in step S400, based on the first approximation degree and the second approximation degree, the calculation formula for the target load value is obtained as follows:

[0086] Wherein, represents the target load value; represents the first approximation degree; represents the second approximation degree; represents the current minimum load value; represents the current maximum load value.

[0087] Step S500: Based on the target load value, update the current minimum load value and the current maximum load value.

[0088] It should be clear that in step S400, the target load value has been found within the range of the current minimum load value and the current maximum load value. Next, the load value corresponding to the maximum apparent power at the maximum load value and the minimum load value (hereinafter referred to as the first load value) and the target load value (hereinafter referred to as the second load value) are used to form a new load range. That is, if the first load value is less than the second load value, then the first load value is used as the new current minimum load value, and the second load value is used as the current maximum load value; if the first load value is greater than the second load value, then the second load value is used as the new current minimum load value, and the first load value is used as the current maximum load value.

[0089] Step S600: Based on the updated current minimum load value and the current maximum load value, perform detection to obtain the capacity of the power transformer.

[0090] It should be clear that after obtaining the new current minimum load value and the current maximum load value, steps S100 to S500 are re-executed until the capacity of the power transformer (i.e., the maximum apparent power of the power transformer) is obtained. It should be clear that it is difficult to accurately obtain the rated capacity of the power transformer. In order to avoid the above method falling into an infinite loop, in this application, if the difference between the maximum apparent power obtained in the last cycle and the maximum apparent power obtained in the previous 5 cycles is less than 1%, then the average value of the maximum apparent power of the power transformer in the last 5 cycles can be used as the capacity of the power transformer.

[0091] It should be clear that, compared with the method of testing the rated capacity of a power transformer by gradually increasing the load in the prior art, the present application intelligently selects the target load value through an iterative method. When the test load range is large, it can quickly narrow the test load range. When the test load range is small, it can quickly find the maximum apparent power of the power transformer. This not only improves the test accuracy, but also significantly improves the test efficiency, shortens the test time, and ensures a faster and more reliable acquisition of the rated capacity of the power transformer.

[0092] After introducing a method for detecting the capacity of a power transformer proposed by the present application, the following introduces an embodiment of a system for detecting the capacity of a power transformer proposed by the present application. As Figure 2 shown, the power transformer capacity detection system 10 includes: An acquirer 11, configured to acquire the current minimum load value and the current maximum load value; A controller 12, configured to acquire first detection data and second detection data based on the current minimum load value and the current maximum load value; the first detection data is the detection data corresponding to the power transformer when it is at the current minimum load value; the second detection data is the detection data corresponding to the power transformer when it is at the current maximum load value; the detection data at least includes the current value, voltage value, and apparent power value of the power transformer; A processor 13, configured to acquire a first approximation degree and a second approximation degree based on the first detection data and the second detection data; the first approximation degree is at least used to characterize the difference between the target load value and the current minimum load value; the second approximation degree is at least used to characterize the difference between the target load value and the current maximum load value; and, based on the first approximation degree and the second approximation degree, acquire the target load value; and, based on the target load value, update the current minimum load value and the current maximum load value; The controller 12 is further configured to perform detection based on the updated current minimum load value and current maximum load value, and then acquire the capacity of the power transformer.

[0093] As a specific embodiment of the present application, the processor 13 is further configured to acquire a validity value based on the detection data; the validity value is at least used to characterize the validity of the apparent power value in the detection data; the detection data includes the first detection data and the second detection data.

[0094] As a specific embodiment in this application, the processor 13 is further configured to obtain the effective voltage value based on the detection data; the effective voltage value is at least used to characterize the magnitude of the fluctuation difference between the input voltage and the output voltage during the detection of the power transformer; and, obtain the effective current value based on the detection data; the effective current value is at least used to characterize the magnitude of the difference between the output current and the theoretical output current during the detection of the power transformer; and, obtain the effectiveness value based on the effective voltage value and the effective current value.

[0095] As a specific embodiment in this application, the calculation formula for the processor 13 to obtain the effective voltage value based on the detection data is as follows:

[0096] where, represents the effective voltage value; n represents the number of voltage values included in the detection data; represents the turns ratio of the primary coil to the secondary coil in the power transformer; represents the i-th input voltage in the detection data; represents the i-th output voltage in the detection data; represents taking the absolute value; is a constant, and is greater than 0 and less than or equal to 1; The calculation formula for the processor 13 to obtain the effective current value based on the detection data is as follows:

[0097] where, represents the effective current value; n represents the number of current values included in the detection data; exp represents the exponential function with base e; represents the i-th input current in the detection data; represents the theoretical output current of the power transformer under the current load; represents the effective voltage value; The calculation formula for the processor 13 to obtain the effectiveness value based on the effective voltage value and the effective current value is as follows:

[0098] where Y represents the effectiveness value; represents the effective voltage value; represents the average value of the output voltage after a preset time in the detection data under the current load; represents the effective current value; It represents the average output current in the detected data after a preset time under the current load; the preset time is greater than or equal to 10 minutes.

[0099] As a specific embodiment in the present application, the processor 13 is further configured to obtain an instability value based on the first detected data and the second detected data; the instability value is at least used to characterize the magnitude of the fluctuation difference of the voltage and / or current in the first detected data and the second detected data; and, based on the instability value, obtain an overload value; the overload value is at least used to characterize the magnitude of the possibility of power transformer overload in the first detected data and the second detected data; and, based on the overload value, obtain the first approximation degree and the second approximation degree.

[0100] As a specific embodiment in the present application, the calculation formula for the processor 13 to obtain an instability value based on the first detected data and the second detected data is as follows:

[0101] Wherein, represents the instability value corresponding to the voltage; n represents the number of voltage values included in the detected data, and n is greater than or equal to 5; represents that the normalization function is used to map the value within the brackets to the range of [0, 1]; represents the i-th input voltage in the first detected data, where i is greater than or equal to 1 and less than or equal to n; represents the j-th input voltage in the first detected data, where j is greater than or equal to 1, and i is greater than or equal to i - 2 and less than or equal to i + 2; represents the i-th input voltage in the second detected data; represents the j-th input voltage in the second detected data; represents taking the absolute value.

[0102] As a specific embodiment in the present application, the calculation formula for the processor 13 to obtain an overload value based on the instability value is as follows:

[0103] Wherein, represents the overload value; represents the effective value of the voltage corresponding to the first detected data; represents the effective value of the voltage corresponding to the second detected data; represents the instability value corresponding to the voltage; represents the effective value of the current corresponding to the first detected data; represents the effective value of the current corresponding to the second detected data; Represents the instability value corresponding to the current.

[0104] As a specific embodiment in this application, the processor 13 obtains the calculation formula for the first approximation degree based on the overload value as follows:

[0105] Wherein, Represents the first approximation degree; Represents the overload value; Represents the validity value corresponding to the first detection data; The processor 13 obtains the calculation formula for the second approximation degree based on the overload value as follows:

[0106] Wherein, Represents the second approximation degree; Represents the overload value; Represents the validity value corresponding to the second detection data.

[0107] As a specific embodiment in this application, the processor 13 obtains the calculation formula for the target load value based on the first approximation degree and the second approximation degree as follows:

[0108] Wherein, Represents the target load value; Represents the first approximation degree; Represents the second approximation degree; Represents the current minimum load value; Represents the current maximum load value.

[0109] It should be clear that, compared with the method of testing the rated capacity of a power transformer by gradually increasing the load in the prior art, the power transformer capacity detection system proposed in this application intelligently selects the target load value through an iterative method. In the case of a large test load range, it can quickly narrow the test load range. In the case of a small test load range, it can quickly find the maximum apparent power of the power transformer. It not only improves the test accuracy, but also significantly improves the test efficiency, shortens the test time, and ensures a faster and more reliable acquisition of the rated capacity of the power transformer.

[0110] It should be clear that the computer-readable storage medium in this application includes both permanent and non-permanent, removable and non-removable media, and information storage can be achieved by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory, static random access memory, dynamic random access memory, other types of random access memory, read-only memory, electrically erasable programmable read-only memory, flash memory, or other memory technologies, compact disc read-only memory, digital versatile disc, or other optical storage, magnetic cassette tapes, disk storage, or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media do not include transient computer-readable media such as modulated data signals and carrier waves.

[0111] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0112] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described methods, devices, and equipment can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0113] In several embodiments provided by the embodiments of this application, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules is only a logical function division. In actual implementation, there may be other division methods. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling, direct coupling, or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of the devices or modules can be in an electrical, mechanical, or other form.

[0114] The modules described as separate components may or may not be physically separated. The components shown as modules may or may not be physical modules, that is, they can be located in one place or distributed to multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0115] In addition, in each embodiment of this application, each functional module can be integrated into one processing module, or each module can exist physically alone, or two or more modules can be integrated into one module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0116] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product.

[0117] The computer program product includes one or more computer instructions. When the computer program is loaded and executed on a computer, it generates in whole or in part the processes or functions described in the embodiments of this application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (such as coaxial cable, optical fiber, digital subscriber line) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a digital video disc), or a semiconductor medium (such as a solid-state drive (SSD)).

[0118] Although the embodiments of this application have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles of this application.

Claims

1. A method for detecting the capacity of a power transformer, characterized in that, Including: Obtain the current minimum load value and the current maximum load value; The load value at least includes the power value output during the operation of the power transformer; The current minimum load value and the current maximum load value are updated from the historical minimum load value and the historical maximum load value; Based on the current minimum load value and the current maximum load value, obtain first detection data and second detection data; the first detection data is the detection data corresponding to the power transformer when it is at the current minimum load value; the second detection data is the detection data corresponding to the power transformer when it is at the current maximum load value; the detection data at least includes the current value, voltage value, and apparent power value of the power transformer; Based on the first detection data and the second detection data, obtain a first approximation degree and a second approximation degree; the first approximation degree is at least used to characterize the difference between the target load value and the current minimum load value; The second approximation degree is at least used to characterize the difference between the target load value and the current maximum load value; Based on the first approximation degree and the second approximation degree, obtain the target load value; Based on the target load value, update the current minimum load value and the current maximum load value; Based on the updated current minimum load value and current maximum load value, perform detection, and then obtain the capacity of the power transformer.

2. The power transformer capacity detection method according to claim 1, wherein Before obtaining the first approximation degree and the second approximation degree based on the first detection data and the second detection data, the method further includes: Based on the detection data, obtain a validity value; the validity value is at least used to characterize the validity of the apparent power value in the detection data; the detection data includes the first detection data and the second detection data.

3. The power transformer capacity detection method according to claim 2, characterized in that, Obtaining the validity value based on the detection data includes: Based on the detection data, obtain the effective voltage value; the effective voltage value is at least used to characterize the fluctuation difference between the input voltage and the output voltage during the detection of the power transformer; Based on the detection data, obtain the effective current value; the effective current value is at least used to characterize the difference between the output current and the theoretical output current during the detection of the power transformer; Based on the effective voltage value and the effective current value, obtain the validity value.

4. The power transformer capacity detection method according to claim 3, wherein The calculation formula for obtaining the effective voltage value based on the detection data is as follows: Among them, represents the effective value of voltage; n represents the number of voltage values included in the detection data; represents the turns ratio of the primary coil to the secondary coil in the power transformer; represents the i-th input voltage in the detection data; represents the i-th output voltage in the detection data; represents taking the absolute value; is a constant, and is greater than 0 and less than or equal to 1; The calculation formula for obtaining the effective current value based on the detection data is as follows: Among them, represents the effective value of current; n represents the number of current values included in the detection data; exp represents the exponential function with the natural constant e as the base; represents the i-th input current in the detection data; represents the theoretical output current of the power transformer under the current load; represents the effective value of voltage; The calculation formula for obtaining the validity value based on the effective voltage value and the effective current value is as follows: Among them, Y represents the validity value; represents the effective voltage value; represents the average value of the output voltage after a preset time in the detection data under the current load; represents the effective current value; represents the average value of the output current after a preset time in the detection data under the current load; the preset time is greater than or equal to 10 minutes.

5. The power transformer capacity detection method according to claim 4, characterized in that Obtaining the first approximation degree and the second approximation degree based on the first detection data and the second detection data includes: Based on the first detection data and the second detection data, obtain an instability value; the instability value is at least used to characterize the fluctuation difference of the voltage and / or current in the first detection data and the second detection data; Based on the instability value, obtain an overload value; the overload value is at least used to characterize the possibility of overload of the power transformer in the first detection data and the second detection data; Based on the overload value, obtain the first approximation degree and the second approximation degree.

6. The power transformer capacity detection method according to claim 5, characterized in that, The calculation formula for obtaining the instability value based on the first detection data and the second detection data is as follows: Among them, represents the instability value corresponding to the voltage; n represents the number of voltage values included in the detection data, and n is greater than or equal to 5; represents that the normalization function is used to map the value within the parentheses to the range of [0, 1]; represents the i-th input voltage in the first detection data, where i is greater than or equal to 1 and less than or equal to n; represents the j-th input voltage in the first detection data, where j is greater than or equal to 1, and i is greater than or equal to i - 2 and less than or equal to i + 2; represents the i-th input voltage in the second detection data; represents the j-th input voltage in the second detection data; represents taking the absolute value.

7. The method for detecting the capacity of a power transformer according to claim 6, wherein The calculation formula for obtaining the overload value based on the instability value is as follows: Among them, represents the overload value; represents the effective voltage value corresponding to the first detection data; represents the effective voltage value corresponding to the second detection data; represents the instability value corresponding to the voltage; represents the effective current value corresponding to the first detection data; represents the effective current value corresponding to the second detection data; represents the instability value corresponding to the current.

8. The method for detecting the capacity of a power transformer according to claim 7, characterized in that, The calculation formula for obtaining the first approximation degree based on the overload value is as follows: Among them, represents the first approximation degree; represents the overload value; represents the validity value corresponding to the first detection data; The calculation formula for obtaining the second approximation degree based on the overload value is as follows: Among them, represents the second approximation degree; represents the overload value; represents the validity value corresponding to the second detection data.

9. The method for detecting the capacity of a power transformer according to any one of claims 1 to 8, characterized in that, The calculation formula for obtaining the target load value based on the first approximation degree and the second approximation degree is as follows: Among them, represents the target load value; represents the first approximation degree; represents the second approximation degree; represents the current minimum load value; represents the current maximum load value.

10. A power transformer capacity detection system, characterized in that, Including: An acquirer for acquiring the current minimum load value and the current maximum load value; A controller for obtaining the first detection data and the second detection data based on the current minimum load value and the current maximum load value; the first detection data is the detection data corresponding to the power transformer when it is at the current minimum load value; the second detection data is the detection data corresponding to the power transformer when it is at the current maximum load value; the detection data at least includes the current value, voltage value and apparent power value of the power transformer; A processor for obtaining the first approximation degree and the second approximation degree based on the first detection data and the second detection data; The first approximation degree is at least used to characterize the magnitude of the difference between the target load value and the current minimum load value; The second approximation degree is at least used to characterize the magnitude of the difference between the target load value and the current maximum load value; And obtain the target load value based on the first approximation degree and the second approximation degree; And update the current minimum load value and the current maximum load value based on the target load value; The controller is further configured to perform detection based on the updated current minimum load value and current maximum load value, and then obtain the capacity of the power transformer.

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