A method for determining DC bias current of a transformer and related device

Abstract

The present application discloses a method for determining the DC bias current of a transformer and a related device, which relates to the field of transformers, including: obtaining a measured current signal of the transformer to be measured, the measured current signal including a plurality of cycles of measured current waveforms, summing up the full even harmonic amplitudes of the measured current waveforms of the plurality of cycles, obtaining the full even harmonic amplitude sums corresponding to the measured current waveforms of the plurality of cycles, and determining the measured DC bias current value in the measured current signal based on the full even harmonic amplitude sums corresponding to the measured current waveforms of the plurality of cycles. The present application accurately determines the measured DC bias current value in the measured current signal based on the full even harmonic amplitude sums corresponding to the measured current waveforms of the plurality of cycles, thereby providing a guarantee for the safe operation of the power system.

Description

Technical Field

[0001] The present application relates to the field of transformers, and in particular to a method for determining a transformer DC bias current and a related device. Background Art

[0002] When asymmetric unipolar operation of a high-voltage direct current (HVDC) transmission system or a geomagnetic storm causes DC current to enter the excitation winding, DC magnetic flux can form in the power transformer core, leading to DC bias. Under DC bias, the transformer core rapidly enters saturation, causing operating point drift, excitation current distortion, and half-wave saturation. Furthermore, DC bias can lead to asymmetric core flux, resulting in severe magnetic circuit imbalance and a significant increase in leakage flux, impacting transformer losses, temperature rise, and noise. In severe cases, it can even damage the transformer's insulation, leading to serious failures and directly threatening the safe operation of the power system. Therefore, in transformer fault analysis, determining the magnitude of the DC bias current is crucial for quickly and accurately analyzing the effects of DC bias on the transformer.

[0003] Currently, electromagnetic current transformers are commonly used to measure current in AC lines of power systems. However, electromagnetic current transformers use the principle of electromagnetic induction for measurement. Due to the limitations of the electromagnetic induction principle, electromagnetic current transformers cannot accurately identify and measure the DC bias current flowing into the transformer under test from the AC line. Summary of the Invention

[0004] In view of the above problems, this application provides a method and related device for determining the DC bias current of a transformer to solve the problem that electromagnetic current transformers cannot accurately identify and measure the DC bias current flowing from the AC line into the transformer under test. The specific solution is as follows:

[0005] A first aspect of the present application provides a method for determining a transformer DC bias current, comprising:

[0006] Acquire a measured current signal of the transformer to be tested, wherein the measured current signal includes a plurality of cycles of measured current waveforms;

[0007] The full even harmonic amplitudes of the measured current waveforms of the multiple cycles are summed up respectively to obtain the full even harmonic amplitude sums corresponding to the measured current waveforms of the multiple cycles;

[0008] The measured DC bias current value in the measured current signal is determined according to the sum of all even harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles.

[0009] In a possible implementation, determining the measured DC bias current value in the measured current signal according to the sum of all even harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles includes:

[0010] Determining whether the measured current signal contains a DC bias current signal based on the sum of all even harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles;

[0011] If so, the measured DC bias current value in the measured current signal is determined based on the mapping relationship between the pre-generated set DC bias current value and the full even harmonic amplitude and the measured value, and the full even harmonic amplitude sum corresponding to the measured current waveform of any of the cycles.

[0012] In a possible implementation, determining whether the measured current signal includes a DC bias current signal according to the sum of all even harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles includes:

[0013] Calculating the deviation between the total even harmonic amplitude sum corresponding to the measured current waveform of each target cycle and the reference value to obtain the deviation value of each target cycle, wherein the target cycle refers to a cycle other than the first cycle sorted in chronological order among the multiple cycles, and the reference value refers to the total even harmonic amplitude sum corresponding to the measured current waveform of the first cycle;

[0014] If the deviation values ​​of all the target cycles are less than or equal to a preset deviation threshold, it is determined that the measured current signal includes a DC bias current signal.

[0015] In a possible implementation, calculating the amplitudes of all even harmonics corresponding to the measured current waveform of each target cycle and the deviations from the reference values ​​includes:

[0016] Determining whether the sums of all even-order harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles are all zero;

[0017] If not, then calculate the full even harmonic amplitude corresponding to the measured current waveform of each target cycle and the deviation value from the reference value.

[0018] In a possible implementation, the process of determining the mapping relationship includes:

[0019] Acquiring a plurality of set DC bias current values ​​and basic parameter values ​​of the transformer to be tested;

[0020] Perform simulation calculations based on the multiple set DC bias current values ​​and the basic parameter values ​​to obtain simulated excitation current waveforms corresponding to the multiple set DC bias current values;

[0021] The full even harmonic amplitudes of the simulated excitation current waveforms corresponding to the plurality of set DC bias current values ​​are summed up to obtain the full even harmonic amplitudes and measured values ​​corresponding to the plurality of set DC bias current values;

[0022] The mapping relationship is obtained from the multiple set DC bias current values ​​and the full even harmonic amplitudes and measured values ​​respectively corresponding to the multiple set DC bias current values.

[0023] In one possible implementation, determining the measured DC bias current value in the measured current signal based on a mapping relationship between a pre-generated set DC bias current value, an all-even harmonic amplitude, and a measured value, and a sum of all-even harmonic amplitudes corresponding to the measured current waveform of any one of the cycles, includes:

[0024] Based on the mapping relationship and the reference value, a preset interpolation method is used to obtain a DC bias current value corresponding to the reference value as the measured DC bias current value in the measured current signal.

[0025] A second aspect of the present application provides a device for determining a transformer DC bias current, comprising:

[0026] A measured current acquisition module is used to obtain a measured current signal of the transformer to be tested, wherein the measured current signal includes a measured current waveform of multiple cycles;

[0027] A measured amplitude summing module, configured to sum the amplitudes of all even harmonics of the measured current waveforms of the multiple cycles, to obtain the sums of the amplitudes of all even harmonics corresponding to the measured current waveforms of the multiple cycles;

[0028] The bias current determination module is used to determine the measured DC bias current value in the measured current signal according to the sum of the full even harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles.

[0029] A third aspect of the present application provides a computer program product comprising computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements the method for determining the DC bias current of a transformer according to the first aspect or any implementation of the first aspect.

[0030] A fourth aspect of the present application provides an electronic device, comprising at least one processor and a memory connected to the processor, wherein:

[0031] The memory is used to store computer programs;

[0032] The processor is used to execute the computer program so that the electronic device can implement the transformer DC bias current determination method of the first aspect or any implementation of the first aspect.

[0033] The fifth aspect of the present application provides a computer storage medium, which carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement the method for determining the DC bias current of the transformer according to the first aspect or any implementation method of the first aspect.

[0034] By means of the above technical solution, the method for determining the DC bias current of a transformer provided by the present application adds up the full even harmonic amplitudes of the measured current waveforms of multiple cycles contained in the measured current signal of the transformer to be measured, and obtains the full even harmonic amplitude sums corresponding to the measured current waveforms of multiple cycles. Considering that for the same transformer, its current waveform under the action of the DC bias current has a single corresponding relationship with the injected DC bias current, and at the same time, the full even harmonic amplitude sum of the current waveform has a single corresponding relationship with the current waveform, thus, different DC bias currents should also have a single corresponding relationship with the full even harmonic amplitude sum in the transformer current waveform. Based on this, this embodiment can accurately determine the measured DC bias current value in the measured current signal based on the full even harmonic amplitude sum corresponding to the measured current waveforms of multiple cycles, thereby providing a guarantee for the safe operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other features, advantages, and aspects of the various embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that the originals and elements are not necessarily drawn to scale.

[0036] Figure 1 A schematic diagram of the system architecture provided for this application;

[0037] Figure 2 This is a schematic diagram of an optional hardware structure of the terminal 100 provided in this application;

[0038] Figure 3 A schematic diagram of the structure of a server 200 provided in this application;

[0039] Figure 4 A schematic flow chart of a method for determining a transformer DC bias current provided in this application;

[0040] Figure 5 The figure below is a comparison of the magnetic flux waveforms under the conditions of DC bias and no DC bias.

[0041] Figure 6 This is the excitation current waveform without DC bias;

[0042] Figure 7 It is the waveform of the excitation current under DC bias;

[0043] Figure 8 This is the proportion of harmonics of each order without DC bias;

[0044] Figure 9 This is the proportion of harmonics of each order under DC bias;

[0045] Figure 10 is the DC bias current waveform;

[0046] Figure 11 It is the waveform of magnetizing inrush current;

[0047] Figure 12 A schematic structural diagram of a device for determining DC bias current of a transformer provided in this application;

[0048] Figure 13 This is a schematic diagram of the structure of an electronic device provided in this application. DETAILED DESCRIPTION

[0049] The following describes the embodiments of the present application in conjunction with the accompanying drawings. The terms used in the implementation methods of the present application are only used to explain the specific embodiments of the present application and are not intended to limit the present application.

[0050] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0051] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, and this is merely a way of distinguishing the objects of the same attributes when describing them in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0052] See also Figure 1 , Figure 1 A schematic diagram of a system architecture is shown. The system may include a terminal 100 and a server 200. The server 200 may include one or more servers ( Figure 1In the example, a server is included), and the server 200 can provide the method provided in the embodiment of the present application for one or more terminals.

[0053] Among them, an application can be installed on the terminal 100, and the above application and web page can provide an interface. The terminal 100 can receive relevant parameters entered by the user on the interface and send the above parameters to the server 200. The server 200 can obtain processing results based on the received parameters and return the processing results to the terminal 100.

[0054] It should be understood that in some optional implementations, the terminal 100 can also complete the action of obtaining the processing result based on the received parameters by itself without the need for the cooperation of the server, and the embodiments of the present application are not limited to this.

[0055] Next describe Figure 1 The product form of the mid-terminal 100;

[0056] The terminal 100 in the embodiment of the present application can be a mobile phone, a tablet computer, a wearable device, a vehicle-mounted device, an augmented reality (AR) / virtual reality (VR) device, a laptop computer, an ultra-mobile personal computer (UMPC), a netbook, a personal digital assistant (PDA), etc., and the embodiment of the present application does not impose any restrictions on this.

[0057] Figure 2 A schematic diagram of an optional hardware structure of the terminal 100 is shown.

[0058] refer to Figure 2 As shown, the terminal 100 may include a radio frequency unit 110, a memory 120, an input unit 130, a display unit 140, a camera 150 (optional), an audio circuit 160 (optional), a speaker 161 (optional), a microphone 162 (optional), an earphone jack 163 (optional), a processor 170, an external interface 180, a power supply 190 and other components. Those skilled in the art will understand that Figure 2 These are merely examples of terminals or multi-function devices and do not limit the terminal or multi-function device. The terminal or multi-function device may include more or fewer components than shown in the figure, or may combine certain components or different components.

[0059] The input unit 130 can be used to receive input digital or character information and generate key signal input related to user settings and function control of the portable multifunction device. Specifically, the input unit 130 may include a touch screen 131 (optional) and / or other input devices 132. The touch screen 131 can detect user touch operations on or near it (for example, operations performed on or near the touch screen using a finger, joint, stylus, or any other suitable object) and drive corresponding connected devices according to pre-set programs. The touch screen can detect user touch actions on the touch screen, convert the touch actions into touch signals and transmit them to the processor 170. It can also receive and execute commands sent by the processor 170; the touch signals include at least touch point coordinate information. The touch screen 131 provides an input interface and an output interface between the terminal 100 and the user. Touch screens can be implemented using various types, including resistive, capacitive, infrared, and surface acoustic wave. In addition to the touch screen 131, the input unit 130 may also include other input devices. Specifically, the other input devices 132 may include, but are not limited to, one or more of a physical keyboard, function keys (such as a volume control key, a switch key, etc.), a trackball, a mouse, a joystick, and the like.

[0060] Among them, the input device 132 can receive input data and the like.

[0061] The display unit 140 may be used to display information input by a user or information provided to the user, various menus of the terminal 100, an interactive interface, file display, and / or playback of any multimedia file.

[0062] Memory 120 can be used to store instructions and data. It primarily includes an instruction storage area and a data storage area. The data storage area can store various data, such as multimedia files and text. The instruction storage area can store software units such as the operating system, applications, and instructions required for at least one function, or subsets or extensions thereof. It may also include non-volatile random access memory (RAM). It provides processor 170 with management functions for the hardware, software, and data resources within the computing and processing device, supporting control software and applications. It is also used to store multimedia files and running programs and applications.

[0063] The processor 170 is the control center of the terminal 100. It connects all components of the terminal 100 using various interfaces and circuits. By executing instructions stored in the memory 120 and accessing data stored therein, it executes various functions of the terminal 100 and processes data, thereby providing overall control of the terminal device. Optionally, the processor 170 may include one or more processing units. Preferably, the processor 170 may integrate an application processor and a modem processor, with the application processor primarily processing the operating system, user interface, and application programs, while the modem processor primarily handles wireless communications. It is understood that the modem processor may not be integrated into the processor 170. In some embodiments, the processor and memory may be implemented on a single chip; in other embodiments, they may be implemented on separate chips. The processor 170 may also generate corresponding operational control signals and send them to the corresponding components of the computing and processing device. It may also read and process data in the software, particularly the data and programs in the memory 120, to enable the various functional modules therein to perform their corresponding functions, thereby controlling the corresponding components to operate as instructed.

[0064] Among them, the memory 120 can be used to store software codes related to the method for determining the DC bias current of the transformer, the processor 170 can execute the steps of the method for determining the DC bias current of the transformer, and can also schedule other units (such as the above-mentioned input unit 130 and display unit 140) to implement corresponding functions.

[0065] The RF unit 110 (optional) can be used to send and receive information or receive and send signals during a call. For example, after receiving downlink information from the base station, it is passed to the processor 170 for processing; in addition, it sends the designed uplink data to the base station. Generally, the RF circuit includes but is not limited to an antenna, at least one amplifier, a transceiver, a coupler, a low noise amplifier (LNA), a duplexer, etc. In addition, the RF unit 110 can also communicate with network devices and other devices via wireless communication. This wireless communication can use any communication standard or protocol, including but not limited to Global System of Mobile Communication (GSM), General Packet Radio Service (GPRS), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), email, Short Messaging Service (SMS), etc.

[0066] In this embodiment of the present application, the radio frequency unit 110 can send data to the server 200 and receive processing results sent by the server 200.

[0067] It should be understood that the radio frequency unit 110 is optional and can be replaced by other communication interfaces, such as a network port.

[0068] The terminal 100 also includes a power supply 190 (such as a battery) for supplying power to various components. Preferably, the power supply can be logically connected to the processor 170 through a power management system, thereby managing functions such as charging, discharging, and power consumption through the power management system.

[0069] The terminal 100 further includes an external interface 180 , which may be a standard Micro USB interface or a multi-pin connector, and may be used to connect the terminal 100 to other devices for communication, or to connect a charger to charge the terminal 100 .

[0070] Although not shown, the terminal 100 may also include a flashlight, a wireless fidelity (WiFi) module, a Bluetooth module, sensors with different functions, etc., which will not be described in detail here. Some or all of the methods described below can be applied to Figure 2 In the terminal 100 shown.

[0071] Next describe Figure 1 The product form of the server 200;

[0072] Figure 3 A structural diagram of a server 200 is provided, such as Figure 3 As shown, the server 200 includes a bus 201, a processor 202, a communication interface 203, and a memory 204. The processor 202, the memory 204, and the communication interface 203 communicate with each other via the bus 201.

[0073] The bus 201 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 3 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0074] The processor 202 may be any one or more of a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor (MP), or a digital signal processor (DSP).

[0075] The memory 204 may include volatile memory, such as random access memory (RAM). The memory 204 may also include non-volatile memory, such as read-only memory (ROM), flash memory, hard disk drive (HDD), or solid state drive (SSD).

[0076] The memory 204 may be used to store software codes related to the method for determining the DC bias current of the transformer. The processor 202 may execute the steps of the method for determining the DC bias current of the transformer of the chip, and may also schedule other units to implement corresponding functions.

[0077] It should be understood that the above-mentioned terminal 100 and server 200 can be centralized or distributed devices, and the processors in the above-mentioned terminal 100 and server 200 (such as processor 170 and processor 202) can be hardware circuits (such as application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), general-purpose processors, DSPs, microprocessors or microcontrollers, etc.), or a combination of these hardware circuits. For example, the processor can be a hardware system with an instruction execution function, such as a CPU, DSP, etc., or a hardware system without an instruction execution function, such as an ASIC, FPGA, etc., or a combination of the above-mentioned hardware systems without an instruction execution function and hardware systems with an instruction execution function.

[0078] The present application provides a method for determining a DC bias current of a transformer. The method for determining a DC bias current of a transformer according to an embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0079] Reference Figure 4 , Figure 4 A flowchart of a method for determining a transformer DC bias current is provided in an embodiment of the present application. The method may include:

[0080] Step S401: Acquire a measured current signal of the transformer to be tested, where the measured current signal includes a plurality of cycles of measured current waveforms.

[0081] Considering that when the transformer is operating normally, the main magnetic flux will be generated in the transformer under the excitation of the excitation current (the current of the transformer when the secondary side is no-loaded is the excitation current); when DC current invades the transformer winding, the DC current will generate DC magnetic flux in the iron core. After the DC magnetic flux is superimposed on the AC main magnetic flux generated by the normal excitation of the transformer, the main magnetic flux will be biased to a certain extent. Figure 5 The comparison diagram of the flux waveforms under the conditions of DC bias and no DC bias is shown. Compared with the flux waveform without DC bias, the flux waveform with DC bias appears to shift upward.

[0082] Furthermore, the DC current invades the transformer winding, causing the transformer's excitation current to change from Figure 6 The symmetrical peak wave distortion of the positive and negative half cycles is shown as Figure 7 The asymmetric peak wave with severe distortion in the positive and negative half cycles is shown.

[0083] right Figure 6 and Figure 7 The excitation currents shown are analyzed in depth and the results show that Figure 6The current waveform of the transformer excitation current under symmetrical excitation (i.e., without DC bias) is mainly composed of the fundamental wave and harmonics of various orders such as the third, fifth, and seventh orders, as shown in FIG. Figure 8 As shown in Figure 1, its structure contains almost no even harmonics. Figure 7 The current waveform of the transformer excitation current under DC bias conditions contains not only the fundamental wave, third, fifth, seventh and other odd harmonics, but also obvious even harmonics such as second, fourth, sixth, etc. Figure 9 .

[0084] At the same time, the harmonic sources in the power system mainly include transformer equipment and various power electronic equipment. Under normal circumstances, these equipment only generate odd harmonics such as the third, fifth and seventh orders, and only when the transformer core is biased and excited will it generate even harmonics such as the second, fourth and sixth orders.

[0085] That is to say, regardless of whether the secondary side is connected to a load, as long as the transformer operates normally, its current will almost only produce odd harmonics and no even harmonics; and as long as the transformer core is biased and excited, its current will produce relatively obvious even harmonics and odd harmonics at the same time.

[0086] Considering the numerous odd harmonic interference sources in power systems, which can interfere with the transformer's current waveform when subjected to DC bias current, it is not possible to determine whether the transformer current contains DC bias current by comparing the odd harmonic content in the transformer current. Therefore, the only way to determine whether the transformer current contains DC bias current is to use the even harmonics in the transformer current.

[0087] Through extensive analysis and calculation, it was discovered that for the same transformer, the current waveform under the action of DC bias current has a single correspondence with the injected DC bias current. At the same time, the amplitude sum of all even harmonics of the current waveform also has a single correspondence with the current waveform. Therefore, different DC bias currents should also have a single correspondence with the amplitude sum of all even harmonics in the transformer current waveform. At the same time, since the transformer only produces stable even harmonics when DC bias current flows into the winding, by comparing the amplitude sum of all even harmonics in the transformer current waveform, it is possible to determine whether DC bias current exists and eliminate the influence of system harmonic interference sources. This also verifies that even harmonics in the transformer current can be used for discrimination.

[0088] Core bias excitation involves two conditions: DC transformer bias and inrush current (including magnetizing inrush current and response inrush current). Both conditions produce a certain amount of even harmonics in the transformer's current waveform. Therefore, while the presence of even harmonics can be used to distinguish between no DC bias and core bias excitation, it is not possible to distinguish between DC transformer bias and inrush current.

[0089] To distinguish between DC bias and inrush current in transformers, the present invention conducted further research. While both DC bias and inrush current produce a certain amount of even harmonics in the transformer's current waveform, there are still differences between the two: the amplitude variation trends of the even harmonics in each cycle of the transformer's current waveform differ.

[0090] Based on this, this embodiment can obtain the measured current waveform of multiple cycles of the transformer to be tested, where the cycle here refers to a complete cycle.

[0091] The number of cycles in this embodiment is expressed as Indicates that the measured current signal is expressed as Expressed as follows:

[0092] Formula (1);

[0093] in, Indicates the The measured current waveform of a cycle; Indicates the sampling moment, that is, the moment when the actual current waveform is measured, ; Represents a cycle.

[0094] Optional, .

[0095] Step S402 : summing up the amplitudes of all even-order harmonics of the measured current waveforms of multiple cycles to obtain the sums of the amplitudes of all even-order harmonics corresponding to the measured current waveforms of multiple cycles.

[0096] As mentioned above, the amplitude variation trend of the even harmonics of the current waveform of each cycle of the transformer is different. For details, please refer to Figure 10 and Figure 11 , Figure 10 is the DC bias current waveform, Figure 11 Figure 2 is the waveform of the magnetizing inrush current. It can be seen that when the transformer experiences DC bias, its current waveform remains consistent within each cycle within a certain period of time, with no tendency to attenuate or increase. However, when the transformer experiences magnetizing (or response) inrush current, its current waveform exhibits a tendency to attenuate in the time domain.

[0097] Based on the above findings, the embodiments of the present application can distinguish between DC bias magnetization and inrush current by analyzing the changing trend of the sum of all even harmonic amplitudes within a number of cycles in the time domain. That is, the embodiments of the present application can sum the full even harmonic amplitudes of the measured current waveforms of multiple cycles to obtain the full even harmonic amplitude sums corresponding to the measured current waveforms of multiple cycles. Here, the full even harmonic amplitude sum refers to the sum of the amplitudes of all even harmonic components.

[0098] Step S403 : determining the measured DC bias current value in the measured current signal according to the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles.

[0099] As described above, there is a single corresponding relationship between different DC bias currents and the sum of all even harmonic amplitudes in the transformer current waveform. Based on this, this embodiment can obtain the measured DC bias current value in the measured current signal according to the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles.

[0100] The method for determining the DC bias current of a transformer provided in the present application is to sum up the full even harmonic amplitudes of the measured current waveforms of multiple cycles contained in the measured current signal of the transformer to be measured, and obtain the full even harmonic amplitude sums corresponding to the measured current waveforms of multiple cycles. Considering that for the same transformer, its current waveform under the action of the DC bias current has a single corresponding relationship with the injected DC bias current, and at the same time, the full even harmonic amplitude sum of the current waveform has a single corresponding relationship with the current waveform, thus, different DC bias currents should also have a single corresponding relationship with the full even harmonic amplitude sum in the transformer current waveform. Based on this, this embodiment can accurately determine the measured DC bias current value in the measured current signal based on the full even harmonic amplitude sum corresponding to the measured current waveforms of multiple cycles, thereby providing a guarantee for the safe operation of the power system.

[0101] In some embodiments of the present application, the process of the above “step S402, respectively summing up the full even harmonic amplitudes of the measured current waveforms of multiple cycles to obtain the full even harmonic amplitude sums corresponding to the measured current waveforms of multiple cycles” is introduced.

[0102] For ease of description, the following takes any one of multiple cycles as an example to introduce a process of obtaining the sum of all even-order harmonic amplitudes corresponding to the measured current waveform of the cycle.

[0103] First, the embodiment of the present application can perform the highest order of the measured current waveform of the cycle as follows: The fast Fourier transform of the measured current waveform of this cycle is used to obtain all the harmonic components of the order, and then all the even harmonic components are obtained. Here, is a positive integer greater than 1.

[0104] It should be noted that the highest order of Fourier decomposition of each period is same.

[0105] Optional, is 30.

[0106] Next, the embodiment of the present application adds up the amplitudes of all even harmonic components of the measured current waveform of the period to obtain the total even harmonic amplitude sum corresponding to the measured current waveform of the period.

[0107] The above process is performed on each of the multiple cycles, and thus the sum of the amplitudes of all even-order harmonics corresponding to the measured current waveforms of the multiple cycles can be obtained.

[0108] For example, the measured current signal in the above formula can be obtained as follows after fast Fourier transform:

[0109] Formula (2);

[0110] Among them, FFT transform means fast Fourier transform; Indicates the The measured current waveform of the cycle is obtained by fast Fourier transform Order harmonic components.

[0111] Assumptions The amplitude is , then:

[0112] Formula (3);

[0113] in, Indicates the The sum of the amplitudes of all even harmonics corresponding to the measured current waveform for a cycle.

[0114] That is, this embodiment can simply and quickly obtain the even harmonic components of the measured current waveform of each cycle through fast Fourier transform, so as to quickly obtain the amplitude sum of all even harmonics, thereby improving the efficiency of determining the measured DC bias current value.

[0115] It should be noted that the above-mentioned method of using fast Fourier transform to obtain the even harmonic components of each measured current waveform of each period is only an example. In addition to this, there may be other implementation methods, for example, using sliding window iterative discrete Fourier transform (DFT) harmonic detection method, harmonic detection method based on instantaneous reactive power theory, instantaneous calculation method harmonic extraction method and other methods to obtain the even harmonic components of each measured current waveform of each period, which is not limited in this application.

[0116] The following describes the process of "step S403, determining the measured DC bias current value in the measured current signal according to the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles" described above.

[0117] As previously described, there is a single correspondence between different DC bias currents and the sum of all even harmonic amplitudes in the transformer current waveform. Based on this, in one possible implementation, this embodiment can pre-find the correspondence between different DC bias currents and the sum of all even harmonic amplitudes in the transformer current waveform through various methods such as simulation or actual measurement. That is, this embodiment can pre-generate a mapping relationship between a set DC bias current value and the sum of all even harmonic amplitudes. Then, based on the mapping system and the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles, the measured DC bias current value in the measured current signal is obtained.

[0118] Optionally, the process of determining the above-mentioned mapping relationship may include: obtaining multiple set DC bias current values ​​and basic parameter values ​​of the transformer to be tested; performing simulation calculations based on the multiple set DC bias current values ​​and basic parameter values ​​to obtain simulated excitation current waveforms corresponding to the multiple set DC bias current values; summing up the full even harmonic amplitudes of the simulated excitation current waveforms corresponding to the multiple set DC bias current values ​​to obtain the full even harmonic amplitudes and measured values ​​corresponding to the multiple set DC bias current values; obtaining a mapping relationship from the multiple set DC bias current values ​​and the full even harmonic amplitudes and measured values ​​corresponding to the multiple set DC bias current values.

[0119] Optionally, the step sizes of multiple DC bias current values ​​can be made equal. For example, the step sizes from 0 to 100 can be set in 1A (ampere) steps. Multiple set DC bias current values ​​within the range. Then, a pre-set calculation program is used to calculate the simulated excitation current waveform corresponding to each set DC bias current value according to each set DC bias current value and the basic parameter value of the transformer to be tested, which is recorded as:

[0120] Formula (4);

[0121] in, represents the simulated excitation current signal, Indicates the The simulated excitation current waveform corresponding to a set DC bias current value.

[0122] It should be noted that the A waveform may contain only one cycle.

[0123] Optionally, this embodiment may adopt the same fast Fourier transform as above to obtain the harmonic components of each order of each simulated excitation current waveform contained in the simulated excitation current signal, and then obtain the even harmonic components.

[0124] Formula (5);

[0125] in, Indicates the The simulated excitation current waveform corresponding to the set DC bias current value is obtained by fast Fourier transform Order harmonic components.

[0126] Furthermore, the sum of all even-order harmonic amplitudes of the simulated excitation current waveform corresponding to each set DC bias current value may be calculated as the sum of all even-order harmonic amplitudes corresponding to each set DC bias current value.

[0127] Assumptions The amplitude is , then:

[0128] Formula (6);

[0129] in, Indicates the The full even harmonic amplitude and measured value corresponding to a set DC bias current value.

[0130] Therefore, this embodiment can establish the mapping relationship shown in Table 1 below.

[0131] Table 1 Mapping relationship between set DC bias current value and full even harmonic amplitude and measured value

[0132]

[0133] For the convenience of the following description, the mapping relationship in Table 1 above is recorded as .

[0134] Afterwards, this embodiment can obtain the measured DC bias current value in the measured current signal based on the mapping system in Table 1 and the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles.

[0135] As mentioned above, the transformer may be in three operating conditions: no DC bias, with DC bias, and with inrush current. Since the process of obtaining the above mapping relationship is time-consuming and labor-intensive, when the transformer is in the no DC bias or inrush current operating conditions, establishing the above mapping relationship is not only time-consuming and labor-intensive, but also meaningless, and may even result in an erroneous measured DC bias current value.

[0136] In another possible implementation, in order to obtain a more accurate measured DC bias current value, this embodiment can first determine whether the measured current signal contains a DC bias current signal based on the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles. If so, the measured DC bias current value in the measured current signal is determined based on the mapping relationship between the pre-generated set DC bias current value and the all even harmonic amplitude and the measured value, as well as the sum of all even harmonic amplitudes corresponding to the measured current waveform of any cycle.

[0137] The following describes a process of determining whether a measured current signal contains a DC bias current signal based on the sum of all even-order harmonic amplitudes corresponding to the measured current waveforms of multiple cycles.

[0138] As described above, the differences between the three working conditions of no DC bias, with DC bias and inrush current are analyzed. In this embodiment, the specific values ​​and attenuation characteristics of the sum of the amplitudes of all even harmonics in each period can be analyzed in time domain order to distinguish whether the transformer is currently in a DC bias state from the three working conditions, that is, to determine whether the measured current signal contains a DC bias current signal, as follows.

[0139] In order to determine whether the amplitudes of all even harmonics corresponding to the measured current waveforms of multiple cycles have basically no significant changes, the present application provides the following multiple implementation methods.

[0140] The first implementation method: the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles can be sorted in order from small to large or from large to small to obtain the maximum sum of all even harmonic amplitudes and the minimum sum of all even harmonic amplitudes. If the difference between the maximum sum of all even harmonic amplitudes and the minimum sum of all even harmonic amplitudes is less than a preset difference threshold, it is determined that the measured current signal contains a DC bias current signal.

[0141] The second implementation method is to take each cycle except the first cycle (i.e., the cycle with the earliest sampling time) in the multiple cycles as a target cycle, and use the sum of all even harmonic amplitudes corresponding to the measured current waveform of the first cycle as the reference value. Then, calculate the deviation between the sum of all even harmonic amplitudes corresponding to the measured current waveform of each target cycle and the reference value to obtain the deviation value of each target cycle. Optionally, the calculation formula of the deviation value is as follows (7).

[0142] Formula (7);

[0143] in, Indicates the The deviation value of the cycle.

[0144] Then, the deviation values ​​of all target cycles are compared with the preset deviation threshold. If the deviation values ​​of all target cycles are less than or equal to the preset deviation threshold, it is considered that the amplitudes of all even harmonics corresponding to the measured current waveforms of multiple cycles have basically no obvious change, and it is determined that the measured current signal contains a DC bias current signal.

[0145] Optionally, the preset deviation threshold is 3%.

[0146] Of course, the preset deviation threshold may also be other, which is not specifically limited in this application.

[0147] It should also be noted that the two implementation methods provided above are only examples. In addition, there may be other implementation methods, which are not specifically limited in this application.

[0148] In a possible implementation, considering that the equivalence judgment process is more time-saving, labor-saving, and resource-saving than the processes of sorting, addition, subtraction, multiplication, and division, based on this, optionally, before implementing the two aforementioned implementation methods, this embodiment can first determine whether the sum of the amplitudes of all even harmonics corresponding to the measured current waveforms of multiple cycles are all 0, that is, whether the following formula (8) is valid.

[0149] Formula (8).

[0150] If so, that is, the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles is all 0, that is, formula (8) holds, then it means that the current transformer is in a no-DC bias condition, then it can be determined that the measured current signal does not contain a DC bias current signal.

[0151] If not, that is, the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles is not all 0, that is, formula (8) does not hold, then execute any of the above two implementation methods. For example, when the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles is not all 0, then calculate the deviation of the sum of all even harmonic amplitudes corresponding to the measured current waveform of each target cycle from the reference value. If the deviation values ​​of all target cycles are less than or equal to the preset deviation threshold, it is determined that the measured current signal contains a DC bias current signal.

[0152] In another possible implementation, this embodiment can also use a preset attenuation analysis method to determine whether the amplitudes of all even harmonics and the sums of all even harmonics corresponding to the measured current waveforms of multiple cycles have an obvious attenuation trend in a chronological order. For example, the amplitudes of all even harmonics and the sums of all even harmonics corresponding to the measured current waveforms of multiple cycles are fitted using a least squares method to obtain a fitting straight line. Based on the relationship between the slope of the fitting straight line and a preset slope threshold, it is determined whether there is an obvious attenuation trend in a chronological order.

[0153] If so, it means that the even harmonics in the measured current signal are mainly caused by the excitation surge current and / or the response surge current, then it is determined that the measured current signal does not contain a DC bias current signal; if not, execute any of the above two implementation methods to determine whether the measured current signal contains a DC bias current signal.

[0154] After determining that the measured current signal contains a DC bias current signal according to the above-mentioned implementation method, this embodiment can determine the measured DC bias current value in the measured current signal based on the mapping relationship between the pre-generated set DC bias current value and the full even harmonic amplitude and the measured value, as well as the full even harmonic amplitude sum corresponding to the measured current waveform of any period.

[0155] See also Figure 10 When the transformer has DC bias, its current waveform remains consistent in each cycle within a certain period of time. Based on this, optionally, this embodiment can determine the measured DC bias current value in the measured current signal based on the mapping relationship between the pre-generated set DC bias current value and the full even harmonic amplitude and the measured value, and the above-mentioned reference value (that is, the full even harmonic amplitude sum corresponding to the measured current waveform of the first cycle sorted in time sequence).

[0156] Optionally, based on the mapping relationship and the reference value, a preset interpolation method may be used to obtain a DC bias current value corresponding to the reference value as the measured DC bias current value in the measured current signal, that is:

[0157] Formula (9);

[0158] in, Indicates the measured DC bias current value; and Represents a mapping relationship The point on Indicates the preset interpolation method; It represents the reference value, i.e., the sum of all even harmonic amplitudes corresponding to the measured current waveform of the first cycle in the multiple cycles sorted in time sequence; Represents an interpolation operation.

[0159] Optionally, the interpolation method may be one or more of a linear interpolation method, a spline interpolation method, and a polynomial interpolation method.

[0160] Among them, the linear interpolation method is a simple and commonly used interpolation technique. This method assumes that the data change between two known points is linear, so the value of the unknown data point can be estimated or predicted based on the linear relationship.

[0161] Spline interpolation is a commonly used interpolation method in numerical analysis and computer graphics. It estimates or predicts the values ​​of unknown data points by constructing a smooth curve (or spline) between known data points.

[0162] Polynomial interpolation is an important technique in numerical analysis. It uses polynomial functions to approximate known data points, thereby constructing a polynomial that can accurately pass through these points.

[0163] Of course, the above interpolation method can also be other methods, which are not specifically limited in this application.

[0164] The method for determining the DC bias current of a transformer provided by the present application is to add up the amplitudes of all even harmonics of the measured current waveforms of multiple cycles contained in the measured current signal of the transformer to be measured, and obtain the sum of the amplitudes of all even harmonics corresponding to the measured current waveforms of multiple cycles. Considering that the measured current waveform of the transformer to be measured when there is no DC bias is composed of odd harmonics, while the measured current waveforms under the two working conditions of DC bias and inrush current contain obvious even harmonics, the amplitude change trends of the even harmonics in each cycle under the two working conditions of DC bias and inrush current are different. Based on this, this embodiment can determine whether the measured current signal contains a DC bias current signal based on the sum of the amplitudes of all even harmonics corresponding to the measured current waveforms of multiple cycles. If so, the measured DC bias current value in the measured current signal is determined based on the mapping relationship between the pre-generated set DC bias current value and the amplitude of all even harmonics and the measured value, and the sum of the amplitudes of all even harmonics corresponding to the measured current waveform of any cycle. It can be seen from this that the present application can pre-generate a mapping relationship between a set DC bias current value and the full even harmonic amplitude and the measured value through simulation, first determine whether the measured current signal contains a DC bias current signal, and only calculate the specific measured DC bias current value when it contains a DC bias current signal, thereby improving the overall calculation efficiency. When it is determined that a DC bias current signal exists in the measured current signal, the measured DC bias current value in the measured current signal can be accurately obtained based on the mapping relationship, providing a guarantee for the safe operation of the power system.

[0165] A method for determining a DC bias current of a transformer provided in an embodiment of the present application has been described above. A device for executing the above method for determining a DC bias current of a transformer will be described below.

[0166] See also Figure 12 , Figure 12 This is a schematic diagram of the structure of a device for determining DC bias current of a transformer provided in an embodiment of the present application. Figure 12 As shown, the device may include:

[0167] The measured current acquisition module 501 is used to obtain the measured current signal of the transformer to be tested, where the measured current signal includes a plurality of cycles of measured current waveforms;

[0168] A measured amplitude summing module 502 is configured to sum the amplitudes of all even harmonics of the measured current waveforms of multiple cycles to obtain the sums of the amplitudes of all even harmonics corresponding to the measured current waveforms of multiple cycles;

[0169] The bias current determination module 503 is configured to determine the measured DC bias current value in the measured current signal according to the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles.

[0170] In a possible implementation, the bias current determination module may include: a bias current determination module and a measured current value determination module;

[0171] A bias magnetic determination module is used to determine whether the measured current signal contains a DC bias magnetic current signal based on the sum of all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles;

[0172] The measured current value determination module is used to determine the measured DC bias current value in the measured current signal based on the mapping relationship between the pre-generated set DC bias current value and the full even harmonic amplitude and the measured value, and the full even harmonic amplitude sum corresponding to the measured current waveform of any period, when the bias judgment module determines that the measured current signal contains a DC bias current signal.

[0173] In a possible implementation, the bias magnetic determination module may include: a Fourier transform module and a deviation value comparison module;

[0174] A Fourier transform module is used to calculate the amplitude of all even harmonics corresponding to the measured current waveform of each target cycle and the deviation from the reference value to obtain the deviation value of each target cycle, wherein the target cycle refers to the cycle other than the first cycle sorted in time sequence among multiple cycles, and the reference value refers to the amplitude of all even harmonics corresponding to the measured current waveform of the first cycle;

[0175] The deviation value comparison module is used to determine that the measured current signal contains a DC bias current signal if the deviation values ​​of all target cycles are less than or equal to a preset deviation threshold.

[0176] In a possible implementation, the Fourier transform module may include an all-zero judgment module and a deviation value determination module;

[0177] The all-zero judgment module is used to judge whether the sum of the amplitudes of all even harmonics corresponding to the measured current waveforms of multiple cycles are all 0;

[0178] The deviation value determination module is used to calculate the full even harmonic amplitude and the deviation value from the reference value corresponding to the measured current waveform of each target cycle when the full zero judgment module determines that the full even harmonic amplitude and the full even harmonic amplitude corresponding to the measured current waveform of multiple cycles are not all zero.

[0179] In a possible implementation, the process of determining the mapping relationship by the measured current value determination module may include:

[0180] Obtain multiple set DC bias current values ​​and basic parameter values ​​of the transformer to be tested;

[0181] Perform simulation calculations based on multiple set DC bias current values ​​and basic parameter values ​​to obtain simulated excitation current waveforms corresponding to the multiple set DC bias current values;

[0182] The full even harmonic amplitudes of the simulated excitation current waveforms corresponding to the multiple set DC bias current values ​​are summed up to obtain the full even harmonic amplitudes and measured values ​​corresponding to the multiple set DC bias current values;

[0183] A mapping relationship is obtained from the multiple set DC bias current values ​​and the full even harmonic amplitudes and measured values ​​corresponding to the multiple set DC bias current values.

[0184] In a possible implementation, the above-mentioned measured current value determination module can be specifically used to: based on the mapping relationship and the reference value, use a preset interpolation method to obtain the DC bias current value corresponding to the reference value as the measured DC bias current value in the measured current signal.

[0185] The transformer DC bias current determination device provided in the embodiment of the present application corresponds to the transformer DC bias current determination method provided above. For details, please refer to the above introduction and will not be repeated here.

[0186] An electronic device is also provided in an embodiment of the present application. Figure 13 , which shows a schematic diagram of the structure of an electronic device suitable for implementing the embodiments of the present application. The electronic device in the embodiments of the present application may include, but is not limited to, fixed terminals such as mobile phones, laptops, PDAs (personal digital assistants), PADs (tablet computers), desktop computers, etc. Figure 13 The electronic device shown is merely an example and should not limit the functions and scope of use of the embodiments of the present application.

[0187] like Figure 13As shown, the electronic device may include a processing device (e.g., a central processing unit, a graphics processing unit, etc.) 601, which can perform various appropriate actions and processes based on programs stored in a read-only memory (ROM) 602 or programs loaded from a storage device 608 into a random access memory (RAM) 603. When the electronic device is powered on, the RAM 603 also stores various programs and data required for the operation of the electronic device. The processing device 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0188] Typically, the following devices may be connected to the I / O interface 605: an input device 606 including, for example, a touch screen, a touchpad, a keyboard, a mouse, a camera, a microphone, an accelerometer, a gyroscope, etc.; an output device 607 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; a storage device 608 including, for example, a memory card, a hard disk, etc.; and a communication device 609. The communication device 609 may allow the electronic device to communicate with other devices wirelessly or by wire to exchange data. Figure 13 The electronic device is shown with various devices, but it should be understood that it is not required to implement or possess all of the devices shown. More or fewer devices may be implemented or possessed instead.

[0189] An embodiment of the present application also provides a computer program product including computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements any of the methods for determining the DC bias current of a transformer provided in the embodiments of the present application.

[0190] A computer-readable storage medium is also provided in an embodiment of the present application. The storage medium carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any of the transformer DC bias current determination methods provided in the embodiment of the present application.

[0191] It should also be noted that the device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed across multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. In addition, in the drawings of the device embodiments provided in this application, the connection relationship between the modules indicates that there is a communication connection between them, which can be specifically implemented as one or more communication buses or signal lines.

[0192] Through the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course can also be implemented by special hardware including application-specific integrated circuits, special CPUs, special memories, special components, etc. In general, all functions performed by computer programs can be easily implemented with corresponding hardware, and the specific hardware structures used to implement the same function can also be diverse, such as analog circuits, digital circuits or special circuits, etc. However, for the present application, software program implementation is a better implementation method in most cases. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer's floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk or optical disk, etc., and includes a number of instructions to enable a computer device (which can be a personal computer, training equipment, or network equipment, etc.) to execute the methods described in each embodiment of the present application.

[0193] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

[0194] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. 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 computer-readable storage medium. For example, the computer instructions can be transmitted from a website, a computer, a training device or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website, a computer, a training device or a data center. The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a training device, a data center, etc. that includes one or more available media integrations. The available medium can be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

Claims

1. A method for determining a transformer DC bias current, characterized in that: include: Acquire a measured current signal of the transformer to be tested, wherein the measured current signal includes a plurality of cycles of measured current waveforms; The full even harmonic amplitudes of the measured current waveforms of the multiple cycles are summed up respectively to obtain the full even harmonic amplitude sums corresponding to the measured current waveforms of the multiple cycles; Calculating the deviation between the total even harmonic amplitude sum corresponding to the measured current waveform of each target cycle and the reference value to obtain the deviation value of each target cycle, wherein the target cycle refers to a cycle other than the first cycle sorted in chronological order among the multiple cycles, and the reference value refers to the total even harmonic amplitude sum corresponding to the measured current waveform of the first cycle; If the deviation values ​​of all the target cycles are less than or equal to a preset deviation threshold, it is determined that the measured current signal contains a DC bias current signal; Based on the mapping relationship between the pre-generated set DC bias current value and the full even harmonic amplitude and the measured value, and the full even harmonic amplitude sum corresponding to the measured current waveform of any of the cycles, the measured DC bias current value in the measured current signal is determined.

2. The method for determining the DC bias current of a transformer according to claim 1, wherein: The calculating of the full even harmonic amplitude corresponding to the measured current waveform of each target cycle and the deviation from the reference value includes: Determining whether the sums of all even-order harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles are all zero; If not, then calculate the full even harmonic amplitude corresponding to the measured current waveform of each target cycle and the deviation value from the reference value.

3. The method for determining the DC bias current of a transformer according to claim 1, wherein: The process of determining the mapping relationship includes: Acquiring a plurality of set DC bias current values ​​and basic parameter values ​​of the transformer to be tested; Perform simulation calculations based on the multiple set DC bias current values ​​and the basic parameter values ​​to obtain simulated excitation current waveforms corresponding to the multiple set DC bias current values; The full even harmonic amplitudes of the simulated excitation current waveforms corresponding to the plurality of set DC bias current values ​​are summed up to obtain the full even harmonic amplitudes and measured values ​​corresponding to the plurality of set DC bias current values; The mapping relationship is obtained from the multiple set DC bias current values ​​and the full even harmonic amplitudes and measured values ​​respectively corresponding to the multiple set DC bias current values.

4. The method for determining the DC bias current of a transformer according to claim 1, wherein: The method of determining the measured DC bias current value in the measured current signal based on the mapping relationship between the pre-generated set DC bias current value, the full even harmonic amplitude, and the measured value, and the full even harmonic amplitude sum corresponding to the measured current waveform of any one of the cycles, comprises: Based on the mapping relationship and the reference value, a preset interpolation method is used to obtain a DC bias current value corresponding to the reference value as the measured DC bias current value in the measured current signal.

5. A device for determining DC bias current of a transformer, characterized in that: include: A measured current acquisition module is used to obtain a measured current signal of the transformer to be tested, wherein the measured current signal includes a measured current waveform of multiple cycles; A measured amplitude summing module, configured to sum the amplitudes of all even harmonics of the measured current waveforms of the multiple cycles, to obtain the sums of the amplitudes of all even harmonics corresponding to the measured current waveforms of the multiple cycles; a bias current determination module, configured to determine a measured DC bias current value in the measured current signal based on the sum of all even harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles; The bias current determination module includes a Fourier transform module, a deviation value comparison module and a measured current value determination module: a Fourier transform module, configured to calculate the sum of all even harmonic amplitudes corresponding to the measured current waveform of each target cycle and a deviation from a reference value, to obtain the deviation value of each target cycle, wherein the target cycle refers to a cycle other than the first cycle sorted in chronological order among the multiple cycles, and the reference value refers to the sum of all even harmonic amplitudes corresponding to the measured current waveform of the first cycle; a deviation value comparison module, configured to determine that the measured current signal contains a DC bias current signal if the deviation values ​​of all the target cycles are less than or equal to a preset deviation threshold; The measured current value determination module is used to determine the measured DC bias current value in the measured current signal based on the mapping relationship between the pre-generated set DC bias current value and the full even harmonic amplitude and the measured value, as well as the full even harmonic amplitude sum corresponding to the measured current waveform of any one of the cycles.

6. A computer program product, characterized in that The method comprises computer-readable instructions, which, when executed on an electronic device, enable the electronic device to implement the method for determining the DC bias current of a transformer as claimed in any one of claims 1 to 4.

7. An electronic device, characterized in that: comprising at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs; The processor is configured to execute the computer program so that the electronic device can implement the method for determining the DC bias current of a transformer as claimed in any one of claims 1 to 4.

8. A computer storage medium, characterized in that The storage medium carries one or more computer programs, and when the one or more computer programs are executed by an electronic device, the electronic device can implement the method for determining the DC bias current of a transformer as described in any one of claims 1 to 4.

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