Transformer inrush current identification method and system based on sampling value image space distribution characteristics

Abstract

The invention relates to the field of power system relay protection, and provides a transformer inrush current identification method and system based on sampling value image space distribution characteristics, a voltage and current sampling sequence is introduced, a # imgabs0 # sampling value image space distribution concept is defined, image space distribution characteristics of # imgabs1 # sampling values of a transformer under different working conditions are analyzed, and the transformer inrush current identification method and system based on the sampling value image space distribution characteristics are obtained. According to the symmetry and the shape difference of image space distribution, a transformer inrush current identification and closing fault identification criterion based on # imgabs2 sampling value image space distribution characteristics is provided, the current type of a transformer is identified according to the identification criterion, different operation conditions of the transformer are set respectively to carry out example simulation on the provided method, and the method is used for identifying the inrush current of the transformer and identifying the inrush current of the transformer according to the shape difference of the # imgabs2 sampling value image space distribution characteristics. The result shows that the identification method is accurate and reliable, the inrush current can be effectively identified, and differential protection misoperation is prevented.

Description

Technical Field

[0001] The present invention relates to the field of relay protection of power systems, and more specifically, to a transformer inrush current identification method and system based on spatial distribution characteristics of sampled value images, aiming to accurately and quickly identify inrush currents in complex and diverse working conditions, effectively prevent the possibility of misoperation or refusal of transformer current differential protection, and ensure rapid protection response and system stability. Background Art

[0002] With the continuous expansion of the scale of power systems and the improvement of their intelligence level, the monitoring and identification of inrush current and fault current of transformers, as key equipment in power transmission and distribution networks, has become particularly important. When transformers are put into operation, they usually generate large inrush currents, which not only affect the normal operation of the equipment, but may also cause equipment damage and instability of the power system.

[0003] Therefore, accurate identification of inrush current and fault current is crucial to ensure the safe and stable operation of the power system. At present, the research on this aspect mainly proposes a study on an adaptive second harmonic excitation inrush current braking scheme based on additional phase discrimination (Yuan Yubo, Lu Yuping, Li Cheng, etc. Study on an adaptive second harmonic excitation inrush current braking scheme based on additional phase discrimination [J]. Proceedings of the CSEE, 2006, 26(18): 19-24.). This method is insufficient in anti-interference ability. When the excitation inrush current is large, the second harmonic content may be less than 15%, resulting in the inability of the differential protection to be normally locked.

[0004] Another method is a method for identifying excitation inrush current and fault current based on long short-term memory neural network (Zhang Guodong, Liu Kai, Pu Haitao, et al. Identification method of excitation inrush current and fault current based on long short-term memory neural network [J]. Journal of Shanghai Jiaotong University, 2024, 58(05): 730-738. DOI: 10.16183 / j.cnki.jsjtu.2022.352.), but this method has high computational complexity and may not be suitable for real-time or fast response scenarios. Summary of the invention

[0005] In order to solve the risk of failure of the traditional second harmonic identification criterion when the transformer is switched on without load, the present invention provides a transformer inrush current identification method and system based on the spatial distribution characteristics of the sampling value image.

[0006] According to a first aspect of the present invention, there is provided a transformer inrush current identification method based on spatial distribution characteristics of sampled values, comprising:

[0007] Collect the current sequence of the primary side of the transformer and voltage sequence ;

[0008] Based on the current sequence collected and the voltage sequence , build The sampled values ​​are spatially distributed, wherein the current sequence The x-axis is the voltage series Establish a coordinate system for the y-axis;

[0009] according to The sampling values ​​are spatially distributed to identify the current type of the transformer, which includes normal current, inrush current and fault current.

[0010] According to a second aspect of the present invention, there is provided a transformer inrush current identification system based on spatial distribution characteristics of sampled values, comprising:

[0011] Acquisition module, used to collect the current sequence of the primary side of the transformer and voltage sequence ;

[0012] Building blocks for acquiring the current sequence based on and the voltage sequence , build The sampled values ​​are spatially distributed, wherein the current sequence The x-axis is the voltage series Establish a coordinate system for the y-axis;

[0013] Identification module, used to The sampling values ​​are spatially distributed to identify the current type of the transformer, which includes normal current, inrush current and fault current.

[0014] The present invention provides a transformer inrush current identification method and system based on the spatial distribution characteristics of sampling value images, which is based on the transformer inrush current under different operating conditions. The sampling value image spatial distribution characteristics are different and based on The transformer inrush current identification and closing-on-fault identification criteria based on the spatial distribution characteristics of the sampling value image are used to solve the failure risk of the traditional second harmonic identification criteria when the transformer is closed under no-load conditions, thereby improving the reliability of protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A flow chart of a transformer inrush current identification method based on spatial distribution characteristics of sampled value images provided by the present invention;

[0016] Figure 2 It is an overall schematic diagram of the transformer inrush current identification method of the present invention;

[0017] Figure 3When the transformer is operating normally Schematic diagram of spatial distribution of sampled values;

[0018] Figure 4 When the transformer is in fault state Schematic diagram of spatial distribution of sampled values;

[0019] Figure 5 (a) shows an asymmetric surge flow. Schematic diagram of spatial distribution of sampled values;

[0020] Figure 5(b) shows the symmetrical surge flow. Schematic diagram of spatial distribution of sampled values;

[0021] Figure 5 (c) shows the circuit breaker with fault Schematic diagram of spatial distribution of sampled values;

[0022] Figure 6 (a) shows the current and voltage waves of phase A of the Y / △ transformer during normal operation;

[0023] Figure 6 (b) Phase A of the Y / △ transformer during normal operation Schematic diagram of spatial distribution of sampled values;

[0024] Figure 7 (a) is a schematic diagram of the current and voltage waveforms of phase A of the Y / △ transformer when the closing angle is 0°;

[0025] Figure 7 (b) shows the Y / △ transformer phase A when the closing angle is 0° Schematic diagram of spatial distribution of sampled values;

[0026] Figure 8 It is a schematic diagram of the second harmonic content of phase A of the Y / △ transformer when the closing angle is 90°;

[0027] Figure 9 (a) is a schematic diagram of the current and voltage waveforms of phase A of the Y / △ transformer when a phase A ground fault occurs;

[0028] Figure 9 (b) shows the Y / △ transformer when a phase A ground fault occurs Schematic diagram of spatial distribution of sampled values;

[0029] Figure 10 (a) is a schematic diagram of the current and voltage waveforms of phase A of the Y / △ transformer when the circuit breaker is closed with a phase A ground fault;

[0030] Figure 10 (b) shows the Y / △ transformer when the circuit breaker is closed with a phase A ground fault Schematic diagram of spatial distribution of sampled values;

[0031] Fig.11 It is a schematic diagram of the second harmonic content of phase A of the Y / △ transformer when the circuit breaker is closed with a phase A grounding fault;

[0032] Fig.12The present invention provides a structural block diagram of a transformer inrush current identification system based on the spatial distribution characteristics of sampled values. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention can be arbitrarily combined with each other to form a feasible technical solution. This combination is not subject to the constraints of the sequence of steps and / or the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] Figure 1 The present invention provides a flow chart of a transformer inrush current identification method based on the spatial distribution characteristics of the sampled value image, such as Figure 1 and Figure 2 As shown, the method includes:

[0035] Step 1: Collect the current sequence of the primary side of the transformer and voltage sequence .

[0036] It is understandable that when it is necessary to identify the current type of the transformer, the current sequence of the primary side of the transformer over a period of time is collected. and voltage sequence .

[0037] Step 2: Based on the collected current sequence and the voltage sequence , build The sampled values ​​are spatially distributed, wherein the current sequence The x-axis is the voltage series Create a coordinate system for the y-axis.

[0038] It is understandable that step 1 collects the current sequence of the primary side of the transformer over a period of time. and voltage sequence Considering the different amplitudes of voltage and current in different states, the voltage sequence and current sequence are normalized according to the rated value. and voltage sequence ,definition The sampled values ​​are distributed in a rectangular coordinate space, with the vertical axis being the voltage. The sampling sequence of the horizontal axis is the current The sampling sequence.

[0039] Step 3, according to The sampling values ​​are spatially distributed to identify the current type of the transformer, which includes normal current, inrush current and fault current.

[0040] Understandably, according to The sampling value image spatial distribution characteristics are used to judge the transformer working current type. Prior to this, the current sequence of the transformer under different known operating conditions is collected. and voltage sequence , and construct the The spatial distribution of sample values; based on each known operating condition The spatial distribution of the sampled values ​​is analyzed to analyze the transformer under each known operating condition. The sampling value image spatial distribution characteristics, the operating conditions of the transformer include the normal operating condition of the transformer, the fault operating condition of the transformer and the no-load closing operating condition of the transformer.

[0041] Among them, when the transformer is operating normally, the load impedance is basically constant. The spatial distribution of the sampled values ​​is an ellipse with a small difference in long and short radii, which is symmetrical about the X-axis and the Y-axis. Figure 3 As shown, since factors such as the size of the load and the rated capacity of the transformer will affect the size of the current per unit value, the width of the formed ellipse will also change.

[0042] When the transformer fails, the load impedance becomes a short-circuit impedance. The spatial distribution of the sampled values ​​is no longer an ellipse symmetrical about the X-axis and the Y-axis, but an ellipse with a large difference in long and short radii that is tilted toward the first and third quadrants, such as Figure 4 As shown in the figure. Under different fault types, the magnitude of the fault current will change, resulting in The sampling value changes as the size of the current per unit value in the spatial distribution changes.

[0043] When the transformer is switched on without load, an asymmetric inrush current or a symmetric inrush current will be generated on the primary side of the transformer. The sampled values ​​are distributed in an irregular semi-ellipse and are symmetrical about the X-axis, as shown in Figure 5 (a). When a symmetrical inrush current is generated, the transformer The spatial distribution of the sampling value image is a long-necked bottle shape symmetrical about the Y axis, as shown in Figure 5 (b). Since the asymmetric surge current is affected by the closing angle, that is, the amplitude of the asymmetric surge current under different closing angles will change, resulting in The size of the current per unit value in the image space distribution of the sampling value will change, but its image space distribution is still symmetrical about the X-axis; if the transformer is closed with a fault, the transformer The spatial distribution of the sampling values ​​is mainly in the first and third quadrants, forming an irregular graph that is not symmetrical about the X-axis and the Y-axis, as shown in Figure 5 (c). When the circuit breaker is closed under different fault types, the magnitude of the fault current will change, resulting in The sampling value changes as the size of the current per unit value in the spatial distribution changes.

[0044] By analyzing the transformer under different operating conditions The spatial distribution of the sampling values ​​is analyzed to obtain the transformer under different operating conditions. The spatial distribution characteristics of the sampling values ​​can be compared to show the transformer under different working conditions. The spatial distribution characteristics of the sampling values ​​are different. The current and inrush current during normal operation of the transformer are symmetrical, while the fault current is not symmetrical.

[0045] Based on this, according to the current sequence of the primary side of the transformer collected in step 1 and step 2 and voltage sequence The spatial distribution characteristics of the transformer are used to identify the current working state of the transformer.

[0046] Specifically, the primary side of the transformer constructed in step 2 The sampled values ​​are distributed in space, and the transformer The sampling values ​​are distributed in the area enclosed by the first, second, third, and fourth quadrants and the X-axis and Y-axis. , , , ; and respectively calculate the transformer The sampling values ​​are distributed in the area enclosed by the positive X-axis and the Y-axis, the negative X-axis and the Y-axis, the positive Y-axis and the X-axis, and the negative Y-axis and the X-axis. , , , .according to , , , as well as , , , The size relationship between them can be used to identify the current type of the transformer.

[0047] Among them, the normal current identification criterion of the transformer is constructed. When the transformer operates normally, according to the symmetry of the ellipse, its image space distribution satisfies formula (1):

[0048] (1)

[0049] In the formula, S 1 , S 2 , S 3 , S 4 Respectively represent The sampling values ​​are distributed in the area enclosed by the first, second, third, and fourth quadrants and the X-axis and Y-axis; Expressed as The sampling values ​​are distributed in the area enclosed by the positive X-axis and the Y-axis; Expressed as The sampling values ​​are distributed in the area enclosed by the negative X-axis and the Y-axis; Expressed as The sampling values ​​are distributed in the area enclosed by the positive Y axis and the X axis; Expressed as The area where the sample values ​​are distributed on the negative Y axis and the area enclosed by the X axis. , They are respectively represented as the thresholds of area difference.

[0050] Similarly, the inrush current identification criterion of the transformer is constructed. When the transformer is closed under no-load conditions, at least one of the symmetrical inrush current or the asymmetrical inrush current is symmetrical about the X-axis or the Y-axis, and its spatial distribution satisfies equation (2). This criterion blocks the transformer current differential protection to prevent false operation of the no-load closing protection.

[0051] (2)

[0052] Similarly, the fault identification criterion of the transformer is constructed. When the transformer fails or is closed and faulty under no-load conditions, the spatial distribution of the fault image is an irregular graph that does not satisfy equation (1) or equation (2). The criterion is released when combined with the transformer current differential protection.

[0053] The present invention is based on the different operating conditions of the transformer Based on the spatial distribution characteristics of the sampling values, the identification criteria of the normal current, inrush current and fault current of the transformer are constructed. According to the criteria of different current working types, the current working state of the transformer is identified.

[0054] The transformer inrush current identification method based on the spatial distribution characteristics of the sampling value image provided by the present invention is verified by simulation below.

[0055] A set of converter transformer models was built using PSCAD. The two transformers were connected in Y / △ and Y / Y modes respectively. The internal parameters of the transformers were set the same. The capacity of each converter transformer was 732.3MVA, the transformation ratio was 525kV / 286.8kV, and the rated voltages of the Y / Y transformer and the Y / △ transformer were (525 / √3) / 165.59kV and (525 / √3) / (165.59 / √3)kV respectively. The operating conditions of normal system operation, no-load closing, fault state, and closing with fault were simulated and verified respectively. All operating conditions were taken as an example of phase A.

[0056] Example 1: Assume that two transformers are operating normally. At this time, the waveforms of the current and voltage of phase A of the Y / △ transformer are shown in Figure 6 (a). The corresponding The spatial distribution of the sampled values ​​is shown in Figure 6(b). As can be seen from Figure 6(b), S 1 , S 2 , S 3 , S 4 Satisfies formula (1), and ; , so it is identified as normal current.

[0057] Example 2: Set the group of converters to close at 1.0167s without load, that is, the closing angle of phase A is 0°, and the residual magnetism of the two transformers is 0. At this time, the waveforms of the current and voltage of phase A of the Y / △ transformer are shown in Figure 7 (a). The corresponding The spatial distribution of the sampled values ​​is shown in Figure 7(b). As can be seen from Figure 7(b), at this time, S 1 , S 2 , S 3 , S 4 Satisfies formula (2), where ; , so it is identified as asymmetric inrush current and the differential protection is locked. Table 1 shows the identification results under different closing angles, which can be accurately identified as inrush current.

[0058] Table 1 Recognition results at different closing angles

[0059]

[0060] It can be seen from Table 1 that when the closing angle is 90°, the Y / △ transformer A phase generates a symmetrical inrush current. Figure 8 The figure shows the second harmonic content in this case. It can be seen that the second harmonic content is higher than 15% at 1.05s~1.07s, and is less than 15% in the rest of the time period. The second harmonic braking is unlocked and the differential protection malfunctions. Therefore, the traditional second harmonic braking method cannot accurately identify the inrush current.

[0061] Example 3: Assume that a phase A ground fault occurs in the Y / △ transformer at 1s. At this time, the waveforms of the current and voltage of the phase A of the Y / △ transformer are shown in Figure 9 (a). The corresponding The spatial distribution of the sampled values ​​is shown in Figure 9(b). As can be seen from Figure 9(b), S 1 , S 2 , S 3 , S 4 Does not satisfy equation (1) and equation (2), where ; ; ; , so it is identified as fault current at this time, and the differential protection is activated. Table 2 shows the identification results of different faults after the transformer is in normal operation, and they can all be accurately identified as fault current.

[0062] Table 2 Identification results of different faults after normal operation

[0063]

[0064] Example 4: Set the Y / △ transformer to close with a fault at 1.0167s. The fault type is a phase A ground fault. At this time, the waveforms of the current and voltage of the phase A of the Y / △ transformer are shown in Figure 10 (a). The corresponding The spatial distribution of the sampled values ​​is shown in Figure 10(b). As can be seen from Figure 10(b), S 1 , S 2 , S 3 , S 4 Does not satisfy equation (1) and equation (2), where ; ; ; At this time, it is identified as a fault current and the differential protection is activated. Fig.11 is the second harmonic content under this condition. It can be seen that the second harmonic content at this time is higher than 15% at 1.0167s~1.16s. At this time, the differential protection refuses to operate, so the traditional second harmonic braking method cannot accurately identify the inrush current. Table 3 shows the identification results when closing with different faults, which can all be accurately identified as fault current.

[0065] Table 3 Identification results of closing with different faults

[0066]

[0067] See also Fig.12 , a transformer inrush current identification system based on the spatial distribution characteristics of sampled value images provided by the present invention, comprising:

[0068] The acquisition module 1201 is used to acquire the current sequence of the primary side of the transformer. and voltage sequence ;

[0069] Building module 1202, for collecting the current sequence based on and the voltage sequence , build The sampled values ​​are spatially distributed, wherein the current sequence The x-axis is the voltage series Establish a coordinate system for the y-axis;

[0070] Identification module 1203, used according to The sampling values ​​are spatially distributed to identify the current type of the transformer, which includes normal current, inrush current and fault current.

[0071] It can be understood that the transformer inrush current identification system based on the spatial distribution characteristics of the sampled value image provided by the present invention is different from the transformer inrush current identification system based on the spatial distribution characteristics of the sampled value image provided by the above embodiments. The transformer inrush current identification method based on the spatial distribution characteristics of the sampling value image is The relevant technical characteristics of the transformer inrush current identification system based on the spatial distribution characteristics of the sampling value image can be referred to The relevant technical features of the transformer inrush current identification method based on the spatial distribution characteristics of the sampling values ​​are not repeated here.

[0072] The present invention provides a method based on The transformer inrush current identification method and system based on the spatial distribution characteristics of the sampling value image have the following beneficial effects:

[0073] (1) Introduce the voltage and current sampling sequence and define The concept of spatial distribution of sampling values ​​is used to analyze the transformer under different working conditions. Based on the image space distribution characteristics of the sampling values, a method based on The sampling value image spatial distribution characteristics of transformer inrush current identification and closing fault identification criteria are used. The current type of the transformer is identified according to the identification criteria. Different operating conditions of the transformer are set to simulate the proposed method. The results show that the identification method proposed in this patent is accurate and reliable, can effectively identify inrush current, and can solve the failure risk of traditional second harmonic identification criteria when the transformer is closed under no-load, effectively prevent the possibility of false operation or refusal of differential protection, and ensure the rapid response of protection and system stability.

[0074] (2) According to the transformer under different working conditions The spatial distribution characteristics of the sampling values ​​can accurately and quickly identify the inrush current of the transformer and are suitable for complex and diverse working conditions.

[0075] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and for parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0076] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0077] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0078] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0079] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0080] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0081] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A transformer inrush current identification method based on the spatial distribution characteristics of sampled values, characterized in that: include: Collect the current sequence of the primary side of the transformer and voltage sequence ; Based on the current sequence collected and the voltage sequence , build The sampled values ​​are spatially distributed, wherein the current sequence The x-axis is the voltage series Establish a coordinate system for the y-axis; according to The sampling values ​​are spatially distributed to identify the current type of the transformer, which includes normal current, inrush current and fault current.

2. The transformer inrush current identification method according to claim 1, characterized in that: The basis The sampling value image spatial distribution characteristics are used to identify the current type of the transformer, which previously included: Collect the current sequence of the transformer under different known operating conditions and voltage sequence , and construct the Sample value image spatial distribution; Based on each known operating condition The spatial distribution of the sampled values ​​is analyzed to analyze the transformer under each known operating condition. The sampling value image spatial distribution characteristics, the operating conditions of the transformer include the normal operating condition of the transformer, the fault operating condition of the transformer and the no-load closing operating condition of the transformer.

3. The transformer inrush current identification method according to claim 2, characterized in that: When the transformer is in normal operation, the load impedance is substantially constant. The spatial distribution of the sampling values ​​is an ellipse that is symmetrical about the X-axis and the Y-axis and has a small difference in long and short radii.

4. The transformer inrush current identification method according to claim 2, characterized in that: When the transformer is in a faulty operating condition, the load impedance becomes a short-circuit impedance. The spatial distribution of the sampling values ​​is an ellipse with a large difference in long and short radii that is inclined toward the first and third quadrants.

5. The transformer inrush current identification method according to claim 2, characterized in that: When the transformer is in no-load closing operation condition, an asymmetric inrush current or a symmetric inrush current is generated on the primary side of the transformer; wherein: When an asymmetrical inrush current occurs, the transformer The sampling value image space distribution is an irregular semi-ellipse and is symmetrical about the X axis; when a symmetrical inrush current is generated, the transformer The spatial distribution of the sampled values ​​is in the shape of a long-necked bottle symmetrical about the Y axis; If the transformer is closed with a fault, the transformer The spatial distribution of the sampling value image is mainly an irregular figure in the first and third quadrants that is not symmetrical about the X-axis and the Y-axis.

6. The transformer inrush current identification method according to claim 1, characterized in that: The basis The sampling value image spatial distribution characteristics are used to identify the current type of the transformer, including: The current sequence of the transformer and the voltage sequence Standardize according to the rated value; Calculate the transformer The sampling values ​​are distributed in the area enclosed by the first, second, third, and fourth quadrants and the X-axis and Y-axis. , , , , and respectively calculate the transformer The sampling values ​​are distributed in the area enclosed by the positive X-axis and the Y-axis, the negative X-axis and the Y-axis, the positive Y-axis and the X-axis, and the negative Y-axis and the X-axis. , , , ; according to , , , as well as , , , The size relationship between them can be used to identify the current type of the transformer.

7. The transformer inrush current identification method according to claim 6, characterized in that: The basis , , , as well as , , , The size relationship between them can be used to identify the current type of the transformer, including: when , , , as well as , , , When the equation (1) is satisfied, the current type of the transformer is normal current; where: (1)； In the formula, , They are respectively expressed as the threshold of area difference; when , , , as well as , , , When the equation (2) is satisfied, the current type of the transformer is inrush current, where: （2）； when , , , as well as , , , When the equation (1) or (2) is not satisfied, the current type of the transformer is a fault current.

8. A transformer inrush current identification system based on the spatial distribution characteristics of sampled values, characterized in that: include: Acquisition module, used to collect the current sequence of the primary side of the transformer and voltage sequence ; Building blocks for acquiring the current sequence based on and the voltage sequence , build The sampled values ​​are spatially distributed, wherein the current sequence The x-axis is the voltage series Establish a coordinate system for the y-axis; Identification module, used to The sampling values ​​are spatially distributed to identify the current type of the transformer, which includes normal current, inrush current and fault current.

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