Method and system for identifying internal and external partial discharge of transformer based on pulse current signal

Abstract

A transformer internal and external partial discharge identification method and system based on a pulse current signal, and the method comprises the steps: collecting output signals of high-frequency pulse current sensors installed at a high-voltage bushing and a bushing end screen grounding part through a signal collection device when a transformer operates, and obtaining a digital high-frequency pulse current signal; whether partial discharge exists or not is judged according to whether the instantaneous value of the pulse current signal reaches a threshold value or not; comparing the wave extreme value, the maximum amplitude and the growth rate of the pulse current signal in a preset time period with a preset threshold value to judge whether the pulse current signal is an effective wave head or not; and judging whether partial discharge occurs in the transformer or not according to the extreme value of the first effective wave of the grounding high-frequency pulse current signals of the bushing and the bushing tap. The discharge defects inside and outside the transformer can be effectively identified, so that a method is provided for reliably identifying the defects of the transformer.

Description

Technical Field

[0001] The present invention belongs to the technical field of power transformers, and particularly relates to a method and system for identifying internal and external partial discharges of transformers based on pulse current signals. Background Art

[0002] Power transformers are key equipment in the power system and also core devices for converting and transmitting electrical energy. The existing power transformers have complex manufacturing processes, and various factors will inevitably cause insulation defects during production, transportation, and operation. Under the action of a strong electric field, these defects may generate partial discharges. When the partial discharge continuously develops into an arc fault and the internal energy of the transformer accumulates continuously, it will cause insulation deterioration and further threaten the safe operation of the transformer. Therefore, being able to effectively identify the partial discharge of the transformer in advance is of great significance for the safe and stable operation of the transformer.

[0003] The high-frequency pulse current method can make full use of partial discharge information, has high pulse resolution, and strong anti-electromagnetic interference ability. Therefore, at present, the high-frequency pulse current detection method is a widely used discharge detection means. The solutions in the prior art include: using the pulse current signals of the bushing and the neutral point, calculating the integral of the signals with time to obtain the discharge amount, and judging the area where the partial discharge occurs through the discharge amount. However, this method has weak anti-interference ability, and when the partial discharge amount is very small, the accuracy of this method is insufficient.

[0004] In addition, most of the existing solutions use electromagnetic wave signals to locate partial discharges. However, these solutions are greatly affected by the electromagnetic environment, have insufficient anti-interference ability, and are computationally complex. Therefore, a new and reliable method for distinguishing partial discharges is needed.

[0005] For example but not limited to, the prior art document 1 (CN102798806A) discloses a method for detecting partial discharges of transformers. Its disadvantages are that the signals measured on the transformer grounding cable are small, vulnerable to interference from the operation of other on-site equipment, and there is obvious attenuation of the pulse current signals, resulting in the problem of misjudging partial discharges; in addition, the on-site operating conditions of the transformer are complex, and the ultrasonic signals are easily interfered by themselves. Therefore, this method has problems of insufficient reliability and misidentification. Summary of the Invention

[0006] To solve the deficiencies in the prior art, the present invention provides a method and system for identifying internal and external partial discharges of transformers based on pulse current signals, which can reduce the influence of interference signals, reduce misidentification, and improve the effectiveness of identifying internal and external discharge defects of transformers.

[0007] The present invention adopts the following technical solutions.

[0008] The first aspect of the present invention provides a method for identifying internal and external partial discharges of a transformer based on pulse current signals, including:

[0009] Real-time collect the output signals of the pulse current sensors installed at the high-voltage bushing and the grounding of the bushing end screen, and obtain a first pulse current signal and a second pulse current signal respectively;

[0010] If the first pulse current signal and the second pulse current signal exceed the threshold value, start oscillograph recording and store the waveforms of the first pulse current signal and the second pulse current signal;

[0011] Calculate the first maximum amplitude in the first pulse current signal in the stored waveform, the first extreme value of the first wavefront corresponding to the first pulse current signal, the second maximum amplitude in the second pulse current signal, and the second extreme value of the first second wavefront corresponding to the second pulse current signal;

[0012] Calculate the first growth rate of the first wavefront corresponding to the first pulse current signal according to the first maximum amplitude and the first extreme value, and calculate the second growth rate of the second wavefront corresponding to the second pulse current signal according to the second maximum amplitude and the second extreme value;

[0013] Judge whether the first wavefront and the second wavefront are valid according to the first growth rate, the second growth rate, the first extreme value and the second extreme value;

[0014] When the first wavefront and the second wavefront are valid, determine the internal partial discharge of the transformer when the first extreme value and the second extreme value have the same sign, otherwise, determine the external partial discharge of the transformer.

[0015] Optionally, the step of starting oscillograph recording if the first pulse current signal and the second pulse current signal exceed the threshold value includes:

[0016] If the first instantaneous value of the first pulse current signal at the current moment is greater than the first threshold value and the second instantaneous value of the second pulse current signal at the current moment is greater than the second threshold value, record the current moment and start oscillograph recording, and store the waveforms of the first pulse current signal and the second pulse current signal within a preset time period starting from the current moment.

[0017] Optionally, calculating the first and second growth rates includes:

[0018] Calculate the absolute value of the slope of the line connecting two data points between the moment of the first extreme point and the previous moment of the current moment t0 as the first growth rate;

[0019] Calculate the absolute value of the slope of the line connecting two data points between the moment of the second extreme point and the previous moment of the current moment t0 as the second growth rate.

[0020] Optionally, the determination of whether the first wavefront and the second wavefront are valid according to the first growth rate, the second growth rate, the first extreme value, and the second extreme value includes:

[0021] Construct a first condition for the magnitudes of the first growth rate and the second growth rate, and construct a second condition for the magnitudes of the first growth rate, the second growth rate, the first extreme value, and the second extreme value;

[0022] If the first condition is satisfied, enter the judgment of the second condition, otherwise the first wavefront and the second wavefront are invalid;

[0023] If the second condition is continuously satisfied, the first wavefront and the second wavefront are valid.

[0024] Optionally, the construction of the first condition for the magnitudes of the first growth rate and the second growth rate includes:

[0025] The first growth rate is greater than a third threshold value and the second growth rate is greater than a fourth threshold value.

[0026] Optionally, the second condition includes at least one of the following:

[0027] The absolute value of the first extreme value is greater than a fifth threshold value, the absolute value of the second extreme value is greater than a sixth threshold value, the first growth rate is greater than a seventh threshold value, and the second growth rate is greater than an eighth threshold value.

[0028] Optionally, the fifth threshold value is the product of the first maximum amplitude and a first preset coefficient, and the sixth threshold value is the product of the second maximum amplitude and a second preset coefficient.

[0029] The second aspect of the present invention provides a transformer internal and external partial discharge identification system based on pulse current signals, and the system includes:

[0030] HFCT, installed at the high-voltage bushing and the ground connection of the bushing end screen, for real-time acquisition of the first pulse current signal and the second pulse current signal;

[0031] Oscillograph, if the first pulse current signal and the second pulse current signal exceed the threshold value, start recording waves and store the waveforms of the first pulse current signal and the second pulse current signal;

[0032] Effective wavefront determination module, used to calculate the first maximum amplitude in the first pulse current signal in the stored waveform, the first extreme value of the first wavefront corresponding to the first pulse current signal, the second maximum amplitude in the second pulse current signal, and the second extreme value of the first wavefront corresponding to the second pulse current signal; and determine whether the first wavefront and the second wavefront are valid;

[0033] An identification and judgment module, which is used to determine internal partial discharge of the transformer when the first extreme value and the second extreme value have the same sign under the condition that the first wave head and the second wave head are valid; otherwise, determine external partial discharge of the transformer.

[0034] A third aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is loaded into the processor, it implements a method for identifying internal and external partial discharges of a transformer based on pulse current signals.

[0035] A fourth aspect of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the above-mentioned method for identifying internal and external partial discharges of a transformer based on pulse current signals.

[0036] Compared with the prior art, the beneficial effects of the present invention at least include:

[0037] The method of the present invention requires real-time collection of the output signals of high-frequency pulse current sensors installed at the high-voltage bushing and the grounding of the bushing end screen of the oil-immersed transformer when the oil-immersed transformer is operating. By comparing whether the instantaneous value of the pulse current signal reaches the threshold value to judge whether there is partial discharge, and then comparing the wave extreme value, maximum amplitude and growth rate of the pulse current signal within the subsequent 20 μs with the preset threshold value to judge whether it is a valid wave head. Finally, based on the extreme value of the first valid wave of the high-voltage bushing and the high-frequency pulse current signal of the bushing end screen grounding, it is judged whether there is internal partial discharge in the transformer, so as to effectively identify the discharge defects inside and outside the transformer. The present invention can reduce the influence of interference signals and greatly improve the effectiveness of identifying discharge defects inside and outside the transformer.

[0038] The present invention uses the high-voltage bushing and the position of the end screen of the high-voltage bushing to collect partial discharge signals. The signal amplitude is large, and the position is close to the pulse current signal with basically no attenuation, and the reliability is high; due to the close positions of the high-voltage bushing and the grounding of the end screen of the high-voltage bushing, the waveform characteristics are not affected by interference. Using the pulse current waveform characteristics for identification has strong anti-interference ability. In addition, the present invention uses the signals of each phase of the transformer to accurately locate the general position where partial discharge occurs, and the reliability is high. In a large-noise environment or a large-interference environment, it is still possible to accurately identify internal and external partial discharges of the transformer. In the case of small internal discharges, the discharge signals can be effectively identified and the position where the discharge occurs can be accurately identified. Description of the Drawings

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0040] Figure 1 is a schematic flow chart of a method for identifying internal and external partial discharges of a transformer based on a pulsed current signal provided by an embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of sensor arrangement provided by an embodiment of the present invention;

[0042] Figure 3 is a time-domain waveform diagram of external interference provided by an embodiment of the present invention;

[0043] Figure 4 is a time-domain waveform diagram of internal discharge provided by an embodiment of the present invention. Detailed implementation manners

[0044] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions of the present invention with reference to the drawings in the embodiments of the present invention. The embodiments described in this application are only a part of the embodiments of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0045] Combined with Figure 1 shown, Embodiment 1 of the present invention provides a method for identifying internal and external partial discharges of a transformer based on a pulsed current signal, which is implemented based on the extreme value characteristics of the high-frequency pulsed current signal waveform, and includes the following steps:

[0046] Step 1: Real-time collect the output signals of the high-frequency pulsed current sensors installed at the high-voltage bushing and the ground of the bushing end screen, and respectively obtain the digital first pulsed current signal H1(t i ) and the second pulsed current signal H2(t i );

[0047] Specifically, combined with Figure 2 shown, HFCT (High Frequency Current Transformer, high-frequency pulsed current sensor) is respectively installed between the high-voltage bushing and the flange of the transformer and on the ground wire of the bushing end screen, and its numbers are T1 and T2. The upper limit of the sampling frequency of the high-frequency pulsed current sensor is 50 MHz. Figure 2In it, the HV (High Voltage) terminal is used to safely lead the high-voltage lead inside the transformer out of the bushing to the external circuit.

[0048] Step 2: According to the first pulse current signal and the second pulse current signal, determine whether to start recording waveforms, and when starting to record waveforms, store the waveforms of the first pulse current signal and the second pulse current signal within a preset time period starting from the current moment.

[0049] Specifically, if the first instantaneous value of the first pulse current signal at the current moment is greater than the first threshold value and the second instantaneous value of the second pulse current signal at the current moment is greater than the second threshold value, record the current moment, start recording waveforms, store the first pulse current signal and the second pulse current signal within a preset time period starting from the current moment, and execute Step 3; otherwise, return to execute Step 1, continue to collect and monitor the first pulse current signal and the second pulse current signal.

[0050] Preferably but not restrictively, based on the first instantaneous value H1(t i ) and the second instantaneous value H2(t i ) of the first pulse current signal and the second pulse current signal at the current moment, determine whether there is partial discharge by whether they are greater than the corresponding threshold values, the first threshold value H1 and the second threshold value H2. If greater, record the current moment as t0, and store the first pulse current signal {H1(t)} and the second pulse current signal {H2(t)} within 20 μs after t0.

[0051] Preferably but not restrictively, both the first threshold value and the second threshold value can be 0.01 A. It can be understood that those skilled in the art can set the specific values of the first threshold value and the second threshold value according to the actual situation.

[0052] Step 3: Calculate the first maximum amplitude in the first pulse current signal in the stored waveforms, the first extreme value of the first wavefront corresponding to the first pulse current signal, the second maximum amplitude in the second pulse current signal, and the second extreme value of the first wavefront corresponding to the second pulse current signal; calculate the first growth rate of the first wavefront corresponding to the first pulse current signal according to the first maximum amplitude and the first extreme value, and calculate the second growth rate of the second wavefront corresponding to the second pulse current signal according to the second maximum amplitude and the second extreme value.

[0053] When the first pulse current signal and the second pulse current signal exceed the first threshold value H1 and the second threshold value H2, take the period from when the first pulse current signal and the second pulse current signal are greater than the first threshold value and the second threshold value to reaching the extreme value and then to being lower than the first threshold value and the second threshold value as the first wavefront. The first extreme value and the second extreme value can be maximum values or minimum values. If taking maximum values, both the first extreme value and the second extreme value take maximum values.

[0054] Preferably but not limited thereto, the corresponding first maximum amplitude A1, second maximum amplitude A2, first extreme value a1 of the first wave crest after the current time t0, and second extreme value a2 of the second wave crest are respectively calculated from the first pulse current signal {H1(t)} and the second pulse current signal {H2(t)} within a preset time period starting from the stored current time t0, and the first growth rate k1 and the second growth rate k2 corresponding to the wave crest are calculated. Preferably but not limited to, the preset time period is 20 μs.

[0055] Preferably but not limited thereto, calculating the first and second growth rates includes:

[0056] Calculating the absolute value of the slope of the line connecting two data points at the time of the first extreme point and the previous moment of the current time t0 as the first growth rate;

[0057] Calculating the absolute value of the slope of the line connecting two data points at the time of the second extreme point and the previous moment of the current time t0 as the second growth rate.

[0058] Specifically, for the first growth rate k1 and the second growth rate k2 of the wave crest corresponding to the pulse current at time t0, the calculation method of the first growth rate k1 is shown in Equation (1):

[0059]

[0060] wherein, a1 is the first extreme value of the first wave crest at the current time t0, H1(t 0-1 ) is the data of the first pulse current signal at the previous moment of t0, t j is the time corresponding to the first extreme value, t 0-1 is the time at the previous moment of t0.

[0061] Similarly, the calculation method of the second growth rate k2 is shown in Equation (2):

[0062]

[0063] wherein, a2 is the second extreme value of the second wave crest at the current time t0, H2(t 0-1 ) is the data of the second pulse current signal at the previous moment of t0, t i is the time corresponding to the second extreme value, t 0-1 is the time at the previous moment of t0.

[0064] Step 4: Judge whether the first wave crest and the second wave crest are valid according to the first growth rate, the second growth rate, the first extreme value, and the second extreme value.

[0065] Construct a first condition based on the magnitudes of the first growth rate and the second growth rate, and construct a second condition based on the magnitudes of the first growth rate, the second growth rate, the first extreme value, and the second extreme value; determine whether the first growth rate and the second growth rate meet the first condition. If they do not meet the first condition, the first wave crest and the second wave crest are invalid; in the case of meeting the first condition, continue to determine whether the first growth rate, the second growth rate, the first extreme value, and the second extreme value meet the second condition; if so, determine that both the first wave crest and the second wave crest are valid, otherwise the first wave crest and the second wave crest are invalid.

[0066] As one of the prominent substantive features of the present invention, the first and second conditions are used for two-level implementation of the judgment, which can quickly screen out invalid wave crests at the first level without having to perform judgments for all criteria, reducing the computational amount.

[0067] Preferably but not restrictively, step 4 specifically includes:

[0068] Step 4.1: Regarding whether the first growth rate k1 and the second growth rate k2 are both greater than the corresponding set thresholds as the first condition. Specifically, if the first growth rate is greater than the third threshold value k 1s and the second growth rate is greater than the fourth threshold value k 2s , then execute step 4.2, otherwise return to execute step 1.

[0069] Further preferably but not restrictively, in this embodiment, the third threshold value k 1s and the fourth threshold value k 2s can both take the value of 5. It can be understood that those skilled in the art can set the specific values of the third threshold value and the fourth threshold value according to actual applications.

[0070] Step 4.2: The second condition includes at least one of the following: the absolute value |a1| of the first extreme value is greater than the fifth threshold value n1A1, the absolute value |a2| of the second extreme value is greater than the sixth threshold value n2A2, the first growth rate k1 is greater than the seventh threshold value k 1t and the second growth rate |a2| is greater than the eighth threshold value k 2t . If the second condition is satisfied, it is considered that both the first wave crest and the second wave crest are valid, and enter step 5, otherwise return to step 1.

[0071] The fifth threshold value is the product of the first maximum amplitude and the first preset coefficient, and the sixth threshold value is the product of the second maximum amplitude and the second preset coefficient.

[0072] Further preferably but not restrictively, in this embodiment, the value ranges of the first preset coefficient n1 and the second preset coefficient n1 are both from 0.1 to 0.2, the seventh threshold value k 1t and the eighth threshold value k 2tBoth are set to 8. It can be understood that those skilled in the art can set the specific values of the first preset coefficient, the second preset coefficient, the seventh threshold value, and the eighth threshold value according to the actual situation.

[0073] In this embodiment, when partial discharge occurs, the effective wavefront is judged by comparing the pulse currents received by the high-voltage bushing and the sensor at the bushing grounding point, and the faults inside and outside the transformer area are further identified by the extreme value of the wavefront. That is, when the extreme values of the effective wavefronts have the same sign, it is internal partial discharge, otherwise it is external partial discharge.

[0074] Step 5: When the first wavefront and the second wavefront are effective, determine internal partial discharge of the transformer when the first extreme value and the second extreme value have the same sign, otherwise determine external partial discharge of the transformer.

[0075] Specifically, if the first extreme value a1>0 and the second extreme value a2>0, or the first extreme value a1<0 and the second extreme value a2<0, then this discharge is an internal defect discharge of the transformer, otherwise this discharge is an external defect discharge of the transformer, and the identification program ends.

[0076] Embodiment 2 of the present invention provides a system for identifying internal and external partial discharges of a transformer based on pulse current signals, which operates the method for identifying internal and external partial discharges of a transformer based on pulse current signals as described in Embodiment 1. The system includes:

[0077] HFCT, installed at the high-voltage bushing and the grounding point of the bushing end screen, for real-time acquisition of the first pulse current signal and the second pulse current signal;

[0078] Oscillograph, if the first pulse current signal and the second pulse current signal exceed the threshold value, starts recording waves and stores the waveforms of the first pulse current signal and the second pulse current signal;

[0079] Effective wavefront determination module, used to calculate the first maximum amplitude in the first pulse current signal in the stored waveform, the first extreme value of the first wavefront corresponding to the first pulse current signal, the second maximum amplitude in the second pulse current signal, and the second extreme value of the first second wavefront corresponding to the pulse current signal; and judge whether the first wavefront and the second wavefront are effective;

[0080] Optionally, the effective wavefront determination module includes a high-frequency pulse current signal maximum amplitude calculation unit, an amplitude growth rate calculation unit, and a wavefront determination unit, where

[0081] High-frequency pulse current signal maximum amplitude calculation unit, used to calculate the first maximum amplitude in the first pulse current signal in the stored waveform, the first extreme value of the first wavefront corresponding to the first pulse current signal, the second maximum amplitude in the second pulse current signal, and the second extreme value of the first second wavefront corresponding to the pulse current signal;

[0082] An amplitude growth rate calculation unit, configured to calculate a first growth rate of a first wavefront corresponding to a first pulse current signal according to a first maximum amplitude and a first extreme value, and calculate a second growth rate of a second wavefront corresponding to a second pulse current signal according to a second maximum amplitude and a second extreme value;

[0083] A wavefront determination unit, configured to determine whether the first wavefront and the second wavefront are valid according to the first growth rate, the second growth rate, the first extreme value, and the second extreme value.

[0084] An identification and judgment module, configured to determine internal partial discharge of the transformer when the first extreme value and the second extreme value have the same sign when the first wavefront and the second wavefront are valid; otherwise, determine external partial discharge of the transformer.

[0085] Regarding the system in the above embodiments, the specific manners in which each unit performs operations have been described in detail in the embodiments related to the method, and will not be elaborated herein.

[0086] Embodiment 3 of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is loaded into the processor, it implements the method for identifying internal and external partial discharge of a transformer based on a pulse current signal described in Embodiment 1.

[0087] Embodiment 4 of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the method for identifying internal and external partial discharge of a transformer based on a pulse current signal described in Embodiment 1.

[0088] Combined Figure 3 、 4 As shown, Embodiment 5 of the present invention provides a verification example to illustrate the feasibility of the solution of the present invention by taking the example of a discharge defect generated inside a certain 110 kV oil-immersed transformer.

[0089] When partial discharge occurs inside and outside the transformer, high-frequency pulse current sensors installed at the high-voltage bushing and the ground wire of the bushing end screen can measure pulse current signals, and the time-domain waveforms are as Figure 3 、 4 shown. Figure 3 is a time-domain waveform diagram of external interference, Figure 4It is a time-domain waveform diagram of internal discharge. The abscissa is the recording time of the high-frequency pulse current recorded in real time, and the ordinate is the real-time value of the high-frequency pulse current recorded in real time. Among them, the solid line represents the waveform of the high-frequency pulse current signal, and the dotted line represents the real-time reference voltage value. It can be seen that when there is external discharge, the extreme values of the grounding signals of the high-voltage bushing and the bushing end screen are opposite; when there is internal discharge, the extreme values of the grounding signals of the high-voltage bushing and the bushing end screen are the same. Therefore, this method can effectively distinguish local discharges inside and outside the transformer area and has strong anti-interference ability.

[0090] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0091] The present disclosure may be a system, method, and / or computer program product. The computer program product may include a computer-readable storage medium having thereon computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0092] A computer-readable storage medium may be a tangible device that can retain and store instructions for use by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of the computer-readable storage medium ((non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory ((CD-ROM), a digital versatile disc ((DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punched card or raised structures in grooves storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage medium used herein is not construed as a transient signal per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagated through a waveguide or other transmission medium ((e.g., optical pulses through an optical fiber cable), or electrical signals transmitted through wires.

[0093] The computer-readable program instructions described herein can be downloaded to various computing / processing devices from a computer-readable storage medium or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in each computing / processing device.

[0094] The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state-setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages such as Smalltalk, C++, etc., and conventional procedural programming languages such as the "C" language or similar programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., connected through the Internet using an Internet service provider). In some embodiments, by using the status information of the computer-readable program instructions to customize an electronic circuit, such as a programmable logic circuit, a field-programmable gate array (FPGA), or a programmable logic array (PLA), the electronic circuit can execute the computer-readable program instructions to implement various aspects of the present disclosure.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: still modifications or equivalent substitutions can be made to the specific embodiments of the present invention, and any modification or equivalent substitution that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for identifying internal and external partial discharges of a transformer based on pulse current signals, characterized in that, Including: Real-time collecting the output signals of pulse current sensors installed at the high-voltage bushing and the grounding of the bushing end screen respectively to obtain a first pulse current signal and a second pulse current signal; If the first pulse current signal and the second pulse current signal exceed the threshold value, start wave recording and store the waveforms of the first pulse current signal and the second pulse current signal; Calculating the first maximum amplitude in the first pulse current signal in the stored waveform, the first extreme value of the first wave head corresponding to the first pulse current signal, the second maximum amplitude in the second pulse current signal, and the second extreme value of the first second wave head corresponding to the second pulse current signal; Calculating the first growth rate of the first wave head corresponding to the first pulse current signal according to the first maximum amplitude and the first extreme value, and calculating the second growth rate of the second wave head corresponding to the second pulse current signal according to the second maximum amplitude and the second extreme value; Judging whether the first wave head and the second wave head are valid according to the first growth rate, the second growth rate, the first extreme value and the second extreme value; When the first wave head and the second wave head are valid, determine internal partial discharge of the transformer when the first extreme value and the second extreme value have the same sign, otherwise, determine external partial discharge of the transformer.

2. The method for identifying internal and external partial discharges of a transformer based on pulse current signals according to claim 1, wherein: The step that if the first pulse current signal and the second pulse current signal exceed the threshold value, start wave recording includes: If the first instantaneous value of the first pulse current signal at the current moment is greater than the first threshold value and the second instantaneous value of the second pulse current signal at the current moment is greater than the second threshold value, record the current moment, start wave recording, and store the waveforms of the first pulse current signal and the second pulse current signal within a preset time period starting from the current moment.

3. The method for identifying internal and external partial discharges of a transformer based on pulse current signals according to claim 1, wherein: Calculating the first and second growth rates includes: Calculating the absolute value of the slope of the line connecting two data points at the moment of the first extreme point and the previous moment of the current moment t0 as the first growth rate; Calculating the absolute value of the slope of the line connecting two data points at the moment of the second extreme point and the previous moment of the current moment t0 as the second growth rate.

4. The method for identifying internal and external partial discharges of a transformer based on pulse current signals according to claim 1, wherein: The step of judging whether the first wave head and the second wave head are valid according to the first growth rate, the second growth rate, the first extreme value and the second extreme value includes: Constructing a first condition for the magnitudes of the first growth rate and the second growth rate, and constructing a second condition for the magnitudes of the first growth rate, the second growth rate, the first extreme value and the second extreme value; If the first condition is satisfied, enter the judgment of the second condition, otherwise the first wave head and the second wave head are invalid; If the second condition is continuously satisfied, the first wave head and the second wave head are valid.

5. The method for identifying internal and external partial discharges of a transformer based on pulse current signals according to claim 4, wherein: The step of constructing a first condition for the magnitudes of the first growth rate and the second growth rate includes: The first growth rate is greater than a third threshold value and the second growth rate is greater than a fourth threshold value.

6. The method for identifying internal and external partial discharges of a transformer based on a pulsed current signal according to claim 4 or 5, characterized in that: The second condition includes at least one of the following: The absolute value of the first extreme value is greater than the fifth threshold value, the absolute value of the second extreme value is greater than the sixth threshold value, the first growth rate is greater than the seventh threshold value, and the second growth rate is greater than the eighth threshold value.

7. The method for identifying internal and external partial discharges of a transformer based on a pulsed current signal according to claim 6, characterized in that: The fifth threshold value is the product of the first maximum amplitude and the first preset coefficient, and the sixth threshold value is the product of the second maximum amplitude and the second preset coefficient.

8. A local discharge recognition system for transformers both inside and outside based on pulse current signals, characterized in that, The system includes: HFCT, installed at the high-voltage bushing and the grounding of the bushing end screen, for collecting the first pulsed current signal and the second pulsed current signal in real time; An oscillograph, which starts recording when the first pulsed current signal and the second pulsed current signal exceed the threshold value, and stores the waveforms of the first pulsed current signal and the second pulsed current signal; An effective wavefront determination module, used to calculate the first maximum amplitude in the first pulsed current signal in the stored waveform, the first extreme value of the first wavefront corresponding to the first pulsed current signal, the second maximum amplitude in the second pulsed current signal, and the second extreme value of the first second wavefront corresponding to the second pulsed current signal; and determine whether the first wavefront and the second wavefront are effective; An identification and judgment module, used to determine internal partial discharge of the transformer when the first extreme value and the second extreme value have the same sign when the first wavefront and the second wavefront are effective, otherwise, determine external partial discharge of the transformer.

9. An electronic device, including a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is used to operate according to the instructions to execute the steps of the method for identifying internal and external partial discharges of a transformer based on a pulsed current signal according to any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, the steps of the method for identifying internal and external partial discharges of a transformer based on a pulsed current signal according to any one of claims 1-7 are implemented.

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