Method for determining direct-current magnetic bias current of transformer and related device

Abstract

The invention discloses a transformer DC magnetic bias current determination method and a related device, and relates to the field of transformers, and the method comprises the steps: obtaining an actual measurement current signal of a to-be-measured transformer, the actual measurement current signal comprises actual measurement current waveforms of a plurality of periods, carrying out the summation of all even harmonic amplitudes of the actual measurement current waveforms of the plurality of periods, and obtaining the sum of all even harmonic amplitudes of all even harmonic amplitudes of all even harmonic amplitudes of all even harmonic amplitudes of all even harmonic amplitudes of all even harmonic amplitudes; all-even harmonic amplitude sums corresponding to the actually measured current waveforms of the multiple periods are obtained, and the actually measured direct current magnetic bias current value in the actually measured current signals is determined according to the all-even harmonic amplitude sums corresponding to the actually measured current waveforms of the multiple periods. According to the method, the actually-measured direct current magnetic bias current value in the actually-measured current signal is accurately determined based on the sum of the all-even harmonic amplitudes corresponding to the actually-measured current waveforms of multiple periods, and a guarantee is provided for safe operation of a 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 the high-voltage direct current transmission system in the power system operates in asymmetric unipolar mode or the direct current current caused by geomagnetic storms enters the excitation winding, direct current magnetic flux will appear in the core of the power transformer and direct current magnetic bias will occur. Under the direct current magnetic bias state, the transformer core quickly enters the saturation state, causing operating point drift, excitation current distortion, half-wave saturation and other phenomena. In addition, direct current magnetic bias will also cause asymmetric operation of the core magnetic flux, making the transformer magnetic circuit seriously unbalanced, and the leakage magnetic flux significantly increased, affecting the transformer's loss, temperature rise and noise problems. In severe cases, it may even cause transformer insulation damage, causing serious faults and directly threatening the safe operation of the power system. Therefore, in the fault analysis of the transformer, it is of great significance to clarify the magnitude of the direct current magnetic bias current for the rapid and accurate analysis of the impact of the transformer suffering from direct current magnetic bias.

[0003] At present, electromagnetic current transformers are usually used to measure the current in the AC line of the power system. 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, the present application provides a method and related device for determining the DC bias current of a transformer to solve the problem that an electromagnetic current transformer cannot be used to accurately identify and measure the DC bias current flowing into the transformer under test from the AC line. The specific solution is as follows:

[0005] The 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-order harmonic amplitudes of the measured current waveforms of the multiple periods are respectively added to obtain the full even-order harmonic amplitude sums corresponding to the measured current waveforms of the multiple periods;

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

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

[0010] Determining whether the measured current signal contains a DC bias current signal according to the sum of all even-order harmonic amplitudes corresponding to the measured current waveforms of the multiple periods;

[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 and corresponding to the measured current waveform of any period.

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

[0013] Calculate the deviation between the full even harmonic amplitude and the reference value corresponding to the measured current waveform of each target cycle to obtain the deviation value of each target cycle, wherein the target cycle refers to the cycle other than the first cycle arranged in chronological order among the multiple cycles, and the reference value refers to the full even harmonic amplitude and the reference value 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 the preset deviation threshold, it is determined that the measured current signal includes a DC bias current signal.

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

[0016] Determine whether the sums of all even-order harmonic amplitudes corresponding to the measured current waveforms of the multiple periods are all 0;

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

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

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

[0020] Perform simulation calculation according to the multiple set DC bias current values ​​and the basic parameter value to obtain simulated excitation current waveforms corresponding to the multiple set DC bias current values ​​respectively;

[0021] The full even harmonic amplitudes of the simulated excitation current waveforms corresponding to the plurality of set DC bias current values ​​are respectively added 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 a possible implementation, 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 and corresponding to the measured current waveform of any period, is used to determine the measured DC bias current value in the measured current signal, including:

[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, used to obtain a measured current signal of the transformer to be tested, wherein the measured current signal includes a plurality of cycles of measured current waveforms;

[0027] A measured amplitude summing module, used for summing up the full even harmonic amplitudes of the measured current waveforms of the multiple periods, to obtain the full even harmonic amplitude sums corresponding to the measured current waveforms of the multiple periods;

[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 all even harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles.

[0029] The third aspect of the present application provides a computer program product, including 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 scheme, the method for determining the DC bias current of a transformer provided by the present application respectively adds up the full even harmonic amplitudes of the measured current waveforms of multiple periods 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 periods. 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 also 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 according to the full even harmonic amplitude sum corresponding to the measured current waveforms of multiple periods, 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 embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

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

[0037] Figure 2 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 diagram of a flow chart of a method for determining a transformer DC bias current provided in the present application;

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

[0041] Figure 6 It 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] Fig. 9 This is the proportion of harmonics of each order under DC bias;

[0045] Fig.10 It is the waveform diagram of DC bias current;

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

[0047] Fig.12 A schematic diagram of the structure of a device for determining a DC bias current of a transformer provided in the present application;

[0048] Fig.13 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 drawings in the embodiments of the present application. The terms used in the implementation method section 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 need not be 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, which is only to describe the distinction mode adopted by the objects of the same attributes when describing 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 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 An optional hardware structure diagram 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 appreciate that Figure 2 These are merely examples of terminals or multi-function devices and do not constitute limitations on the terminals or multi-function devices, which may include more or fewer components than those shown in the figures, or combinations of 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 the user settings and function control of the portable multifunctional device. Specifically, the input unit 130 may include a touch screen 131 (optional) and / or other input devices 132. The touch screen 131 can collect the user's touch operations on or near it (such as the user's operation on or near the touch screen using any suitable object such as fingers, joints, stylus, etc.), and drive the corresponding connection device according to a pre-set program. The touch screen can detect the user's touch action on the touch screen, convert the touch action into a touch signal and send it to the processor 170, and can receive and execute the command sent by the processor 170; the touch signal at least includes the touch point coordinate information. The touch screen 131 can provide an input interface and an output interface between the terminal 100 and the user. In addition, the touch screen can be implemented using multiple types such as resistive, capacitive, infrared and surface acoustic wave. In addition to the touch screen 131, the input unit 130 can also include other input devices. Specifically, 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 provided to a user, various menus of the terminal 100, an interactive interface, file display, and / or playback of any multimedia file.

[0062] The memory 120 can be used to store instructions and data. The memory 120 can mainly include an instruction storage area and a data storage area. The data storage area can store various data, such as multimedia files, texts, etc.; the instruction storage area can store software units such as operating systems, applications, instructions required for at least one function, or their subsets and extensions. It can also include a non-volatile random access memory; provide the processor 170 with hardware, software and data resources including management of computing and processing equipment, and support control software and applications. It is also used for the storage of multimedia files, and the storage of running programs and applications.

[0063] The processor 170 is the control center of the terminal 100. It uses various interfaces and lines to connect various parts of the entire terminal 100. By running or executing instructions stored in the memory 120 and calling data stored in the memory 120, it executes various functions of the terminal 100 and processes data, thereby controlling the terminal device as a whole. Optionally, the processor 170 may include one or more processing units; preferably, the processor 170 may integrate an application processor and a modem processor, wherein the application processor mainly processes the operating system, user interface and application program, and the modem processor mainly processes wireless communication. It is understandable that the above-mentioned modem processor may not be integrated into the processor 170. In some embodiments, the processor and the memory may be implemented on a single chip, and in some embodiments, they may also be implemented separately on separate chips. The processor 170 may also be used to generate corresponding operation control signals, send them to corresponding components of the computing and processing device, read and process data in the software, especially read and process data and programs in the memory 120, so that each functional module therein performs corresponding functions, thereby controlling the corresponding components to act according to the requirements of the instructions.

[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 the display unit 140) to achieve corresponding functions.

[0065] The radio frequency unit 110 (optional) can be used for receiving and sending information or receiving and sending signals during a call, for example, after receiving the downlink information of the base station, it is sent to the processor 170 for processing; in addition, the designed uplink data is sent 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 (Low Noise Amplifier, LNA), a duplexer, etc. In addition, the radio frequency unit 110 can also communicate with network devices and other devices through wireless communication. The wireless communication can use any communication standard or protocol, including but not limited to Global System of Mobile Communication (Global System of Mobile Communication, GSM), General Packet Radio Service (General Packet Radio Service, GPRS), Code Division Multiple Access (Code Division Multiple Access, CDMA), Wideband Code Division Multiple Access (Wideband Code Division Multiple Access, WCDMA), Long Term Evolution (Long Term Evolution, LTE), email, Short Messaging Service (SMS), etc.

[0066] In this embodiment of the present application, the RF 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, so that the power management system can manage functions such as charging, discharging, and power consumption.

[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 communicate with other devices, 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 may be applied in the following embodiments. 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 only 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 a volatile memory, such as a random access memory (RAM). The memory 204 may also include a non-volatile memory, such as a read-only memory (ROM), a flash memory, a hard disk drive (HDD), or a 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, and 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 in conjunction with the accompanying drawings.

[0079] Reference Figure 4 , Figure 4 A schematic flow chart of a method for determining a transformer DC bias current provided in an embodiment of the present application, the method may include:

[0080] Step S401: obtaining a measured current signal of the transformer to be tested, wherein 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 unloaded 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 intrudes into the transformer winding, causing the transformer 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 peaked 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 excitation current of the transformer shown in FIG. 1 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, such as Figure 8 As shown, its composition 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. Fig. 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 devices only generate odd harmonics of the third, fifth and seventh orders, and only when the transformer core is biased and excited will it generate even harmonics of the second, fourth and sixth orders.

[0085] That is to say, no matter whether the secondary side is connected to a load or not, 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 that there are many odd harmonic interference sources in the power system, which will interfere with the current waveform of the transformer when it is subjected to the DC bias current, it is impossible to determine whether the transformer current contains the DC bias current by comparing the odd harmonic content in the transformer current. Therefore, it can only be determined by the even harmonics in the transformer current.

[0087] Through a lot of analysis and calculation, it is found that for the same transformer, its current waveform under the action of DC bias current has a single corresponding relationship with the injected DC bias current. At the same time, the amplitude of all even harmonics of the current waveform also has a single corresponding relationship with the current waveform. Therefore, different DC bias currents and the amplitude of all even harmonics in the transformer current waveform should also have a single corresponding relationship. At the same time, since the transformer will only produce stable even harmonics when DC bias current flows into the winding, by comparing the amplitude of all even harmonics in the transformer current waveform, it can be determined whether there is a DC bias current, and the influence of the system harmonic interference source can also be eliminated. This also verifies that the even harmonics in the transformer current can be used for judgment.

[0088] Since core bias excitation includes two situations, namely transformer DC bias and inrush current (including excitation inrush current and response inrush current), both situations will cause the transformer current waveform to produce a certain amount of even harmonics. Therefore, although it is possible to distinguish between no DC bias and core bias excitation by whether even harmonics are generated, it is impossible to distinguish between transformer DC bias and inrush current.

[0089] In order to distinguish between DC bias and inrush current of transformer, the embodiments of the present application have conducted further research. When DC bias and inrush current occur, although the current waveform of the transformer will produce a certain amount of even harmonics, there is still a difference between the two, that is, the amplitude change trend of the even harmonics of the current waveform of the transformer in each cycle is different.

[0090] Based on this, this embodiment can obtain the actual 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 The measured current signal is expressed as If it is expressed, then:

[0092] Formula (1);

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

[0094] Optional, .

[0095] Step S402: summing up the full even-order harmonic amplitudes of the measured current waveforms of multiple periods to obtain the full even-order harmonic amplitude sums corresponding to the measured current waveforms of multiple periods.

[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 Fig.10 and Fig.11 , Fig.10 is the DC bias current waveform. Fig.11 It is the waveform of the excitation inrush current. It can be seen that when the transformer has a DC bias, its current waveform remains consistent in each cycle within a certain period of time, and there is no tendency of attenuation or enhancement; however, when the transformer has an excitation (or response) inrush current, its current waveform will show a tendency of attenuation 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 the changing trend of the sum of all even harmonic amplitudes in several cycles in the time domain. That is, the embodiments of the present application can add up the full even harmonic amplitudes of the measured current waveforms of multiple cycles respectively, and obtain the full even harmonic amplitude sums corresponding to the measured current waveforms of multiple cycles respectively. Here, the full even harmonic amplitude sum refers to the sum of the amplitudes of all even harmonic components.

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

[0099] As described above, different DC bias currents have a single corresponding relationship with the sum of all even-order 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-order 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 add 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, respectively, to 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 also 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 according to 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 "step S402, respectively adding up the full even-order harmonic amplitudes of the measured current waveforms of multiple periods to obtain the full even-order harmonic amplitude sums corresponding to the measured current waveforms of multiple periods" is introduced.

[0102] For ease of description, the following takes any one of the multiple cycles as an example to introduce the 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 period 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-order harmonic components of the measured current waveform of the period to obtain the total even-order harmonic amplitude sum corresponding to the measured current waveform of the period.

[0107] The above process is performed for each of the multiple cycles, and the sum of the full even-order harmonic amplitudes 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 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 sum of all even-order harmonic amplitudes corresponding to the measured current waveform for a cycle.

[0114] That is, this embodiment can simply and quickly obtain the even harmonic components of each measured current waveform of each period 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 is an introduction to the process of "step S403, determining the measured DC bias current value in the measured current signal according to the sum of all even-order harmonic amplitudes corresponding to the measured current waveforms of multiple cycles" in the previous text.

[0117] Following the introduction above, there is a single correspondence between different DC bias currents and the amplitudes and values ​​of all even harmonics in the transformer current waveform. Based on this, in a possible implementation, this embodiment can find the correspondence between different DC bias currents and the amplitudes and values ​​of all even harmonics in the transformer current waveform in advance through simulation or actual measurement, that is, this embodiment can pre-generate a mapping relationship between the set DC bias current value and the amplitudes and values ​​of all even harmonics. Then, based on the mapping system and the amplitudes and values ​​of all even harmonics 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 the basic parameter values ​​to obtain simulated excitation current waveforms corresponding to the multiple set DC bias current values; adding 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. Then, the preset 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 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 harmonic components of various orders of each simulated excitation current waveform included in the simulated excitation current signal, and then obtain even harmonic components.

[0124] Formula (5);

[0125] in, Indicates 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 full even-order harmonic amplitude sum of the simulated excitation current waveform corresponding to each set DC bias current value may be calculated as the full even-order harmonic amplitude sum measurement value corresponding to each set DC bias current value.

[0127] Assumptions The amplitude is , then:

[0128] Formula (6);

[0129] in, Indicates 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 above and the sum of all even-order harmonic amplitudes corresponding to the measured current waveforms of multiple periods.

[0135] Referring to the previous introduction, the transformer may be in three working conditions: no DC bias, with DC bias and inrush current. Since the process of obtaining the above mapping relationship is time-consuming and labor-intensive, when the transformer is in the condition of no DC bias or inrush current, establishing the above mapping relationship is not only time-consuming and labor-intensive, but also meaningless, and may even result in an erroneous measurement of the actual DC bias current value.

[0136] In another possible implementation, in order to obtain a more accurate measured DC bias current value, the present 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 amplitudes and measured values, as well as the sum of all even harmonic amplitudes corresponding to the measured current waveform of any cycle.

[0137] The following is an introduction to the process of "determining whether the 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, this embodiment can analyze the specific values ​​and attenuation characteristics of the sum of the amplitudes of all even harmonics in each period in time domain order, so as to distinguish whether the transformer is currently in DC bias 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-order 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: each cycle except the first cycle (i.e., the cycle with the earliest sampling time) in the multiple cycles can be taken as a target cycle, and the sum of all even-order harmonic amplitudes corresponding to the measured current waveform of the first cycle is taken as the reference value, and then the deviation between the sum of all even-order harmonic amplitudes corresponding to the measured current waveform of each target cycle and the reference value is calculated to obtain the deviation value of each target cycle. Optionally, the calculation formula of the deviation value is as shown in the following formula (7).

[0142] Formula (7);

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

[0144] Then the deviation values ​​of all target cycles are compared with the preset deviation threshold values. If the deviation values ​​of all target cycles are less than or equal to the preset deviation threshold values, it is considered that the amplitudes of all even harmonics corresponding to the measured current waveforms of multiple cycles have basically no obvious changes, 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, and this application does not specifically limit it.

[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 and 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 all even-order harmonic amplitudes corresponding to the measured current waveforms of multiple periods are all 0, that is, whether the following formula (8) holds.

[0149] Formula (8).

[0150] If so, that is, the amplitudes of all even harmonics and corresponding to the measured current waveforms of multiple cycles are all 0, that is, formula (8) holds, it means that the current transformer is in a non-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-order harmonic amplitudes corresponding to the measured current waveforms of multiple cycles is not all zero, that is, formula (8) does not hold, then execute any of the above two implementation methods. For example, when the sum of all even-order harmonic amplitudes corresponding to the measured current waveforms of multiple cycles is not all zero, then calculate the deviation of the sum of all even-order 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, the present embodiment may also use a preset attenuation analysis method to determine whether the amplitudes of all even harmonics and corresponding to the measured current waveforms of multiple cycles respectively have an obvious attenuation trend in a chronological order. For example, the amplitudes of all even harmonics and 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 one 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 and corresponding to the measured current waveform of any period.

[0155] Still see Fig.10 When the transformer is DC biased, 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 corresponding to the measured current waveform of the first cycle sorted in chronological order).

[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 the mapping relationship The point on Indicates the preset interpolation method; 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 arranged in chronological order; 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 may 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 in 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 all even harmonic amplitudes corresponding to the measured current waveforms of multiple cycles. Considering that the measured current waveform of the transformer to be measured is composed of odd harmonics when there is no DC bias, and the measured current waveform under the two working conditions of DC bias and inrush current contains obvious even harmonics, but the amplitude change trends of the even harmonics of 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 according to 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, and the sum of all even harmonic amplitudes corresponding to the measured current waveform of any cycle. It can be seen 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 transformer DC bias current provided in an embodiment of the present application is introduced above. A device for executing the above method for determining a transformer DC bias current will be introduced below.

[0166] See also Fig.12 , Fig.12 This is a schematic diagram of the structure of a transformer DC bias current determination device provided in an embodiment of the present application. Fig.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, and the measured current signal includes a plurality of cycles of measured current waveforms;

[0168] The measured amplitude summing module 502 is used to sum the full even harmonic amplitudes of the measured current waveforms of multiple periods, to obtain the full even harmonic amplitude sums corresponding to the measured current waveforms of multiple periods;

[0169] The bias current determination module 503 is used 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 according to 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 and 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 above-mentioned 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 value from 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 in the chronological order 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 all even-order harmonic amplitudes 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 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 deviation from the reference value 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 respectively added 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 a plurality of set DC bias current values ​​and full even harmonic amplitudes and measured values ​​respectively corresponding to a plurality of 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 in the previous text. For details, please refer to the previous text and will not be repeated here.

[0186] The present application also provides an electronic device in an embodiment. Fig.13 As shown, it shows a schematic diagram of the structure of an electronic device suitable for implementing the embodiment of the present application. The electronic device in the embodiment 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. Fig.13 The electronic device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0187] like Fig.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 according to a program stored in a read-only memory (ROM) 602 or a program loaded from a storage device 608 to a random access memory (RAM) 603. When the electronic device is powered on, various programs and data required for the operation of the electronic device are also stored in the RAM 603. The processing device 601, the ROM 602, and the RAM 603 are connected to each other 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 touch pad, 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. Although Fig.13 An electronic device having various devices is shown, but it should be understood that it is not required to implement or possess all 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 method for determining a transformer DC bias current provided in the embodiment 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 method for determining the DC bias current of a transformer provided in an embodiment of the present application.

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

[0192] Through the description of the above implementation mode, the technicians in the field can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course, it can also be implemented by special hardware including special integrated circuits, special CPUs, special memories, special components, etc. In general, all functions completed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be various, such as analog circuits, digital circuits or special circuits. However, for the present application, software program implementation is a better implementation mode in more cases. Based on such an 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 floppy disk, a U disk, a mobile hard disk, a ROM, a RAM, a disk or an optical disk, etc., including a number of instructions to enable a computer device (which can be a personal computer, a training device, or a network device, 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 may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may 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 may be transmitted from a website site, 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 site, computer, training device, or data center. The computer-readable storage medium may 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 may 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)), etc.

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-order harmonic amplitudes of the measured current waveforms of the multiple periods are respectively added to obtain the full even-order harmonic amplitude sums corresponding to the measured current waveforms of the multiple periods; The measured DC bias current value in the measured current signal is determined according to the sum of all even-order harmonic amplitudes corresponding to the measured current waveforms of the multiple periods.

2. The method for determining the DC bias current of a transformer according to claim 1, characterized in that: The method of 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 periods, comprises: Determining whether the measured current signal contains a DC bias current signal according to the sum of all even-order harmonic amplitudes corresponding to the measured current waveforms of the multiple periods; 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 and corresponding to the measured current waveform of any period.

3. The method for determining the DC bias current of a transformer according to claim 2, characterized in that: The determining whether the measured current signal contains a DC bias current signal according to the sum of all even harmonic amplitudes corresponding to the measured current waveforms of the multiple periods, comprises: Calculate the deviation between the full even harmonic amplitude and the reference value corresponding to the measured current waveform of each target cycle to obtain the deviation value of each target cycle, wherein the target cycle refers to the cycle other than the first cycle arranged in chronological order among the multiple cycles, and the reference value refers to the full even harmonic amplitude and the reference value 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 the preset deviation threshold, it is determined that the measured current signal includes a DC bias current signal.

4. The method for determining the DC bias current of a transformer according to claim 3, characterized in that: The calculating of the full even harmonic amplitude corresponding to the measured current waveform of each target cycle and the deviation value from the reference value includes: Determine whether the sums of all even-order harmonic amplitudes corresponding to the measured current waveforms of the multiple periods are all 0; If not, then the full even harmonic amplitude corresponding to the measured current waveform of each target cycle and the deviation value from the reference value are calculated.

5. The method for determining the DC bias current of a transformer according to claim 2, characterized in that: The process of determining the mapping relationship includes: Acquire a plurality of set DC bias current values ​​and basic parameter values ​​of the transformer to be tested; Perform simulation calculation according to the multiple set DC bias current values ​​and the basic parameter value to obtain simulated excitation current waveforms corresponding to the multiple set DC bias current values ​​respectively; The full even harmonic amplitudes of the simulated excitation current waveforms corresponding to the plurality of set DC bias current values ​​are respectively added 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.

6. The method for determining the DC bias current of a transformer according to claim 3, characterized in that: The method determines 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 and corresponding to the measured current waveform of any one of the cycles, including: 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.

7. A device for determining a transformer DC bias current, characterized in that: include: A measured current acquisition module, used to obtain a measured current signal of the transformer to be tested, wherein the measured current signal includes a plurality of cycles of measured current waveforms; A measured amplitude summing module, used for summing up the full even harmonic amplitudes of the measured current waveforms of the multiple periods, to obtain the full even harmonic amplitude sums corresponding to the measured current waveforms of the multiple periods; 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 all even harmonic amplitudes corresponding to the measured current waveforms of the multiple cycles.

8. A computer program product, characterized in that It comprises computer-readable instructions, and 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 as claimed in any one of claims 1 to 6.

9. An electronic device, characterized in that: The method comprises at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs; The processor is used to execute the computer program so that the electronic device can implement the method for determining the DC bias current of the transformer as described in any one of claims 1 to 6.

10. 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 6.

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