On-line monitoring method and system for dielectric loss of power transformer, terminal and medium

Abstract

The method comprises the following steps: 1, acquiring voltage and current data by a monitoring terminal, and sending the voltage and current data and a first time mark to an edge node; step 2, if the edge node judges that the first time scale is valid, calculating a dielectric loss angle of the first time scale, and going to step 5; otherwise, proceeding to step 3; 3, the edge node judges that the first time mark is invalid, the monitoring terminal sends the newly collected data and the second time mark to the edge node together, and the time interval between the first time mark and the second time mark is the shortest; if the second time mark is invalid, repeating the step 3, and if the second time mark is valid, entering the step 4; 4, calculating the dielectric loss angle of the second time scale, and correcting the dielectric loss angle of the second time scale by using the time interval to obtain the dielectric loss angle of the first time scale; and 5, calculating the similarity of the dielectric loss angles of any two phases of mutual inductors, and determining that the phase of mutual inductor is abnormal when the two similarities corresponding to any phase of mutual inductor are smaller than a set threshold value. And the timeliness and the accuracy of monitoring the dielectric loss angle of the mutual inductor are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of online monitoring of electric power equipment, and in particular, relates to an online monitoring method and system for dielectric loss of a power mutual inductor, a terminal, and a medium. Background Art

[0002] As a key link in the operation voltage and current data of power equipment under operation status, the power transformer is one of the key sensing nodes of the digital power grid. It converts high voltage or large current data into low voltage or small current data, thereby reducing the measurement pressure and making the measurement more convenient and safe. At the same time, as a key sensing unit of relay protection, the health of the power transformer operation status is one of the main data sources to ensure the judgment of relay protection action. However, power transformers usually operate in high voltage and strong magnetic environments. Due to factors such as harsh operating environment, factory process problems or power grid impact, as the operating years increase, the health of its operating status will show a "bathtub curve" trend. If the operating status of the transformer cannot be effectively evaluated in time, after the transformer is damaged, the current and voltage cannot be accurately measured, which may lead to misjudgment of line faults, thereby affecting the normal operation of the power system and even causing the protection of the power system to fail.

[0003] In the prior art, the operating status monitoring of power transformers adopts offline measurement methods, such as infrared temperature measurement, transformer oil pressure monitoring, partial discharge monitoring, etc. These methods reflect the sub-health status of the transformer to a certain extent, but the transformer status detection method relying on offline measurement is generally regular detection, with a long time interval, and cannot timely reflect the real-time operation of the transformer; the offline measurement method of non-electrical parameters is greatly affected by external factors, such as infrared temperature measurement, which is greatly affected by the ambient temperature at the time of measurement; there is no clear standard to specify the abnormal range of transformer operating temperature, so it is extremely dependent on the manual experience of patrol personnel. Dielectric loss monitoring for capacitive equipment is widely used. Capacitive equipment can be regarded as a pure capacitor and resistor in the actual operation process. When the transformer is abnormal, its dielectric loss angle will change accordingly, which can effectively reflect the health status of the transformer. However, in the prior art, the dielectric loss mainly relies on the offline measurement of the dielectric loss meter, that is, in the power outage state, the dielectric loss meter is used to test the transformer to achieve the evaluation of the transformer status. This method has low timeliness and complex operation. Secondly, the dielectric loss angle is usually a dynamically changing curve. Simply relying on the value of a single measurement to evaluate the operating status of the transformer has low reliability and is not conducive to the effective definition of its status. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a method and system, a terminal and a medium for online monitoring of the dielectric loss of a power transformer, so as to improve the timeliness and accuracy of the monitoring of the dielectric loss angle of the transformer.

[0005] The present invention adopts the following technical solution.

[0006] The present invention proposes an online monitoring method for dielectric loss of a power transformer, comprising:

[0007] Step 1: The monitoring terminal collects voltage data and current data, and sends the collected data together with the corresponding first time stamp to the edge node;

[0008] Step 2: When the edge node determines that the first time scale is valid, the voltage data and the current data are used to calculate the dielectric loss angle under the first time scale by using the fast Fourier transform method, and the process proceeds to step 5; otherwise, the process proceeds to step 3;

[0009] Step 3: When the edge node determines that the first time stamp is invalid, the edge node sends a command to the monitoring terminal to reacquire the voltage and current data. The monitoring terminal sends the reacquired voltage data and current data together with the corresponding second time stamp to the edge node, wherein the time interval between the first time stamp and the second time stamp is the shortest. When the edge node determines that the second time stamp is invalid, step 3 is repeated until the second time stamp is valid and step 4 is entered.

[0010] Step 4, using the voltage data and current data corresponding to the second time scale, using the fast Fourier transform method to calculate the dielectric loss angle at the second time scale, and using the time interval between the first time scale and the second time scale to correct the dielectric loss angle at the second time scale to obtain the dielectric loss angle at the first time scale;

[0011] Step 5: The edge node calculates the dielectric loss angles of the three mutual sensors at multiple time scales, and calculates the similarity of the dielectric loss angles of any two mutual sensors. When the two similarities corresponding to any mutual sensor are less than a set threshold, the mutual sensor is judged to be abnormal.

[0012] Step 1 includes:

[0013] The monitoring terminal synchronously collects three-phase voltage and three-phase current; filters the three-phase voltage and three-phase current; and uses the fast Fourier transform method to collect voltage data and current data within the fundamental frequency range.

[0014] In step 2, whether the time stamp is valid is determined based on the bytes of the time stamp.

[0015] In step 3, the first time mark is t0, the second time mark is t1, and the two time marks satisfy t1-t0-k*0.02≤0, where k is a positive integer; when step 3 is repeated, k is selected starting from 1. When it is determined that the second time mark is also invalid, k is increased by 1 to determine a new second time mark, and so on, so that the time interval between the newly obtained second time mark and the first time mark is the shortest and valid.

[0016] In step 4, the dielectric loss angle at the second time scale is corrected using the time interval between the first time scale and the second time scale, and the dielectric loss angle at the first time scale is calculated using the following relationship:

[0017]

[0018] Δt=t1-t0-(k-1)×0.02

[0019] In the formula, is the dielectric loss angle at the first time scale, is the dielectric loss angle under the second time scale, and Δt is the time interval.

[0020] The dielectric loss angle at the first time scale obtained in step 4 is When , the dielectric loss angle under the first time scale is corrected according to the following relationship:

[0021]

[0022] In the formula, is the correction value of the dielectric loss angle under the first time scale, and n is taken to be satisfy A positive integer.

[0023] In step 5, the similarity of the dielectric loss angles of any two mutual inductors satisfies the following relationship:

[0024]

[0025]

[0026]

[0027] In the formula,

[0028] ρ AB is the similarity of dielectric loss angles of mutual inductors A and B;

[0029] ρ AC is the similarity of dielectric loss angles of mutual inductors A and C;

[0030] ρ BC is the similarity of dielectric loss angles of mutual inductors B and C;

[0031] The time scale is t i The dielectric loss angle of the mutual inductors A, B and C under the condition;

[0032] are the average values ​​of dielectric loss angles of mutual inductors A, B, and C at multiple time scales;

[0033] m is a positive integer, indicating the number of time scales; i is a positive integer, indicating the number of time scales t i Serial number, i = 1, 2, 3,…, m.

[0034] The two similarities corresponding to any mutual sensor are less than the set threshold When the mutual inductor is abnormal, it is judged that the mutual inductor is abnormal, including:

[0035] like It is determined that mutual inductor A is abnormal;

[0036] like It is determined that the mutual inductor B is abnormal;

[0037] like It is determined that the C mutual inductor is abnormal.

[0038] like It is determined that all mutual sensors are normal.

[0039] The present invention also proposes an online monitoring system for dielectric loss of a power transformer, comprising: a monitoring terminal and an edge node;

[0040] A monitoring terminal is used to collect voltage data and current data, and send the collected data together with the corresponding first time stamp to the edge node;

[0041] The edge node is used to determine that when the first time mark is valid, the voltage data and the current data are used to calculate the dielectric loss angle under the first time mark by using the fast Fourier transform method; when the edge node determines that the first time mark is invalid, the edge node sends an instruction to the monitoring terminal to re-acquire the voltage and current data, and the monitoring terminal sends the re-collected voltage data and current data together with the corresponding second time mark to the edge node, wherein the time interval between the first time mark and the second time mark is the shortest; when the edge node determines that the second time mark is invalid, the above operation is repeated until the second time mark is valid, the voltage data and current data corresponding to the second time mark are used to calculate the dielectric loss angle under the second time mark by using the fast Fourier transform method, and the time interval between the first time mark and the second time mark is used to correct the dielectric loss angle under the second time mark to obtain the dielectric loss angle under the first time mark; the dielectric loss angle of the three-phase inductor under multiple time marks is calculated by using the calculated dielectric loss angle, and the similarity of the dielectric loss angle of any two mutual inductors is calculated. When the two similarities corresponding to any mutual inductor are less than the set threshold, the mutual inductor is judged to be abnormal.

[0042] The monitoring terminal includes a voltage unit installed on the line body and a current unit installed on the transformer grounding wire; wherein, the voltage unit is a coupling capacitance sensor, the high and low voltage arms of the sensor are respectively composed of coupling capacitances between the sensor and the earth and between the sensor and the transmission line, and the low voltage arm and the subsequent acquisition and processing circuits are located near the high voltage end to be measured, forming electrical isolation from the low voltage end.

[0043] A terminal comprises a processor and a storage medium; the storage medium is used to store instructions;

[0044] The processor is configured to operate according to the instructions to execute the steps of the method.

[0045] A computer-readable storage medium stores a computer program, which implements the steps of the method when executed by a processor.

[0046] The beneficial effect of the present invention lies in that, compared with the prior art, at least the method proposed by the present invention realizes the calculation and monitoring of the dielectric loss angle of the transformer by monitoring the fundamental voltage and current data under the operating state, and optimizes the traditional offline detection method into an online monitoring method to improve the timeliness of the transformer dielectric loss angle monitoring.

[0047] In actual engineering, due to the particularity of operation in high voltage and strong magnetic environment, the time stamp corresponding to the data collected by the monitoring terminal may be invalid. Once the time stamp is invalid, the calculation of the dielectric loss angle cannot be realized, or errors may occur. The solution proposed in the present invention can solve the calculation of the dielectric loss angle of the mutual inductor when the data time stamp is invalid, and ensure that the monitoring data used to determine whether the three-phase mutual inductor is abnormal has a one-to-one corresponding time stamp.

[0048] The voltage unit proposed in the present invention can reduce the influence of the particularity of operation in high voltage and strong magnetic environment on the data collected by the monitoring terminal in actual engineering, thereby improving the timeliness and effectiveness of data collection. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a flow chart of an online monitoring method for dielectric loss of a power transformer proposed by the present invention;

[0050] Figure 2 is a data processing flow chart of the method for online monitoring of dielectric loss of a power transformer in an embodiment of the present invention;

[0051] Figure 3 is a structural diagram of an online monitoring system for dielectric loss of a power transformer in an embodiment of the present invention;

[0052] Figure 4 is a schematic diagram of the voltage unit principle in an embodiment of the present invention;

[0053] Figure 5 It is the equivalent circuit of the voltage unit in the embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0055] The present invention proposes an online monitoring method for power transformer dielectric loss, such as Figure 1 As shown, including:

[0056] Step 1: The monitoring terminal collects voltage data and current data within the fundamental frequency range; and sends the voltage data and current data within the fundamental frequency range together with the corresponding first time stamp to the edge node.

[0057] The monitoring terminal collects waveform signals including three-phase voltage and three-phase current. Since the transformer dielectric loss angle is calculated based on the phase of fundamental current and voltage, the monitoring terminal collects voltage data and current data within the fundamental frequency range from the collected signals.

[0058] By adopting an online measurement method for measuring the operating voltage and current of the transformer, the operating reliability of the monitoring terminal directly determines the reliability of the online monitoring of the dielectric loss of the power transformer. However, due to the harsh operating environment of the monitoring terminal, the amount of data required to be collected is large. The method proposed in the present invention can greatly reduce the amount of data that the monitoring terminal needs to send signals, thereby improving the reliability of the monitoring terminal.

[0059] Specifically, step 1 includes:

[0060] Step 1.1, the monitoring terminal collects the three-phase voltage u synchronously according to the BD / GPS time A 、u B 、u C With the three-phase current i A 、i B 、i C .

[0061] Step 1.2, filtering the three-phase voltage and three-phase current.

[0062] Step 1.3, using the fast Fourier transform method, collect voltage data and current data within the fundamental frequency range.

[0063] Specifically, obtain the filtered signal and perform fast Fourier transform (FFT) spectrum analysis to obtain a waveform "frequency-amplitude" graph; select the frequency with the largest amplitude value in the waveform "frequency-amplitude" graph, whose vertical axis is amplitude, denoted by F, and the horizontal axis is frequency, and determine whether the coordinate horizontal axis frequency corresponding to F is within the range of [49Hz, 51Hz]. If it is within the frequency range, the data corresponding to the graph is determined to be valid, otherwise, the data corresponding to the graph is determined to be invalid.

[0064] The method proposed in the present invention realizes the calculation and monitoring of the dielectric loss angle by monitoring the fundamental voltage and current data of the transformer under the operating state, and optimizes the traditional offline detection method into an online monitoring method to improve the timeliness of the transformer dielectric loss angle monitoring.

[0065] Step 2: When the edge node determines that the first time mark is valid, the voltage data and current data within the fundamental frequency range are used to calculate the dielectric loss angle under the first time mark using the fast Fourier transform method, and then proceed to step 5; otherwise, proceed to step 3.

[0066] Specifically, the signal data sent by the monitoring terminal to the edge node will carry a time stamp, which indicates the absolute time when the signal data is collected, such as Beijing time, accurate to nanoseconds; the time stamp is divided into "valid and invalid", for example, whether it is Beijing time is determined based on the bytes of the time stamp; if the time stamp is "valid", it means that the collection time of the signal sent by the monitoring terminal to the edge node is correct, such as Beijing time, so the signal data can be used as data for calculating the dielectric loss angle; if the time stamp is "invalid", it means that the collection time is incorrect, and the signal data cannot be used as data for calculating the dielectric loss angle.

[0067] Specifically, the edge node uses the fast Fourier transform method to calculate the dielectric loss angle The initial phase of the phase angle satisfies:

[0068] Step 3: When the edge node determines that the first time stamp is invalid, the edge node sends an instruction to the monitoring terminal to reacquire the voltage and current data. The monitoring terminal sends the re-collected voltage data and current data within the fundamental frequency range together with the corresponding second time stamp to the edge node, where the time interval between the first time stamp and the second time stamp is the shortest. When the edge node determines that the second time stamp is invalid, step 3 is repeated until the second time stamp is valid and step 4 is entered.

[0069] Specifically, the first time mark is t0, and the second time mark is t1. The two time marks satisfy t1-t0-k*0.02≤0, k is a positive integer, and the upper limit is positive infinity. When step 3 is repeated, k is selected from the minimum value 1. When it is determined that the second time mark is also invalid, k is increased by 1 to determine a new second time mark, and so on, so that the time interval between the newly obtained second time mark and the first time mark is the shortest and valid, thereby ensuring that the closest voltage and current data are obtained.

[0070] Step 4, using the voltage data and current data within the fundamental frequency range corresponding to the second time scale, the fast Fourier transform method is used to calculate the dielectric loss angle at the second time scale, and the time interval between the first time scale and the second time scale is used to correct the dielectric loss angle at the second time scale to obtain the dielectric loss angle at the first time scale.

[0071] The dielectric loss angle at the first time scale is calculated using the following relationship:

[0072]

[0073] Δt=t1-t0-(k-1)×0.02

[0074] In the formula, is the dielectric loss angle at the first time scale, is the dielectric loss angle at the second time scale, Δt is the time interval, t1 is the second time scale, t0 is the first time scale, and k is a positive integer.

[0075] Furthermore, the dielectric loss angle at the first time scale obtained in step 4 is When , the dielectric loss angle under the first time scale is corrected according to the following relationship:

[0076]

[0077] In the formula, is the correction value of the dielectric loss angle under the first time scale, and n is taken to be satisfy A positive integer.

[0078] In actual engineering, due to the particularity of operation in high voltage and strong magnetic environment, the time stamp corresponding to the data collected by the monitoring terminal may be invalid. Once the time stamp is invalid, the calculation of the dielectric loss angle cannot be realized, or errors may occur. The solution proposed in the present invention can solve the calculation of the dielectric loss angle of the mutual inductor when the data time stamp is invalid, and ensure that the monitoring data used to determine whether the three-phase mutual inductor is abnormal has a one-to-one corresponding time stamp.

[0079] Since the monitoring terminal does not have the ability to perform complex calculations, in the method proposed by the present invention, the edge node is responsible for the complex calculations and sends the calculation results to the monitoring terminal. The monitoring terminal performs online monitoring of the mutual inductor based on the complex calculation results.

[0080] Step 5: The edge node calculates the dielectric loss angles of the three mutual sensors at multiple time scales, and calculates the similarity of the dielectric loss angles of any two mutual sensors. When the two similarities corresponding to any mutual sensor are less than a set threshold, the mutual sensor is judged to be abnormal.

[0081] Specifically, step 5 includes:

[0082] Step 5.1: The edge node calculates the dielectric loss angle of the three-phase mutual inductor at multiple time scales and constructs the monitoring data set of each mutual inductor.

[0083] In the embodiment, the dielectric loss angle of the three-phase mutual inductor at time t1 is recorded as The dielectric loss angle at time t2 is recorded as And so on, we can get the time scale t i The dielectric loss angle at time The subscripts A, B, and C represent the three phases, and i is a positive integer, which is the time scale t i Serial number, i = 1, 2, 3,…, m.

[0084] Specifically, the monitoring data set of phase A power transformer is recorded as The monitoring data set of phase B power transformer is recorded as The monitoring data set of phase C power transformer is recorded as m is a positive integer, indicating the number of time scales.

[0085] Step 5.2: Based on the monitoring data set, calculate the similarity of the dielectric loss angles of any two mutual inductors, denoted as ρ AB ,ρ AC ,ρ BC .

[0086] In the embodiment, the similarity of the dielectric loss angles of any two mutual inductors satisfies the following relationship:

[0087]

[0088]

[0089]

[0090] In the formula,

[0091] ρ AB is the similarity of dielectric loss angles of mutual inductors A and B;

[0092] ρ AC is the similarity of dielectric loss angles of mutual inductors A and C;

[0093] ρ BC is the similarity of dielectric loss angles of mutual inductors B and C;

[0094] The time scale is t i The dielectric loss angle of the mutual inductors A, B and C under the condition;

[0095] are the average values ​​of the dielectric loss angles of mutual inductors A, B, and C under multiple time scales.

[0096] Step 5.3: When the two similarities corresponding to any mutual sensor are both less than the set threshold, the mutual sensor is judged to be abnormal.

[0097] Specifically, set the threshold When the value is 0.7, step 5.3 includes:

[0098] If AB ≥0.7,ρ AC ≥0.7,ρ BC ≥0.7, then it is determined that all mutual sensors are normal.

[0099] If BC ≥0.7,ρ AB <0.7, ρ AC <0.7, then it is determined that mutual inductor A is abnormal;

[0100] If AC ≥0.7,ρ BC <0.7, ρ AB <0.7, then it is determined that the mutual inductor B is abnormal;

[0101] If AB ≥0.7,ρ AC <0.7, ρ BC <0.7, it is judged that the C mutual inductor is abnormal.

[0102] In actual projects, the transformers of phases A, B, and C are installed in the same batch. If the three transformers are operating normally, the change curves of the dielectric loss angle should be similar. Here, the similarity between the dielectric loss angles of the three transformers is calculated to determine whether the transformers are in a healthy operating state. If the change curves of the dielectric loss angles of phases A and B are similar, but phases A and C and phases B and C are not similar, then there is a problem with the C transformer.

[0103] Applying the above method to actual engineering, the data processing flow is as follows Figure 2 shown.

[0104] The present invention also proposes an online monitoring system for dielectric loss of a power transformer, comprising: a monitoring terminal and an edge node;

[0105] A monitoring terminal is used to collect voltage data and current data, and send the collected data together with the corresponding first time stamp to the edge node;

[0106] The edge node is used to determine that when the first time mark is valid, the voltage data and the current data are used to calculate the dielectric loss angle under the first time mark by using the fast Fourier transform method; when the edge node determines that the first time mark is invalid, the edge node sends an instruction to the monitoring terminal to re-acquire the voltage and current data, and the monitoring terminal sends the re-collected voltage data and current data together with the corresponding second time mark to the edge node, wherein the time interval between the first time mark and the second time mark is the shortest; when the edge node determines that the second time mark is invalid, the above operation is repeated until the second time mark is valid, the voltage data and current data corresponding to the second time mark are used to calculate the dielectric loss angle under the second time mark by using the fast Fourier transform method, and the time interval between the first time mark and the second time mark is used to correct the dielectric loss angle under the second time mark to obtain the dielectric loss angle under the first time mark; the dielectric loss angle of the three-phase inductor under multiple time marks is calculated by using the calculated dielectric loss angle, and the similarity of the dielectric loss angle of any two mutual inductors is calculated. When the two similarities corresponding to any mutual inductor are less than the set threshold, the mutual inductor is judged to be abnormal.

[0107] Specifically, Figure 3 As shown, the monitoring terminal includes a voltage unit installed on the line body and a current unit installed on the transformer grounding wire; wherein, the voltage unit is used to collect the transformer operating voltage, is installed on the bus body on the high-voltage side of the transformer, is powered by solar energy + coupling energy extraction, and uses a capacitor voltage division method to collect the bus voltage; the current unit is installed on the transformer grounding wire, and is used to collect the transformer leakage current; the edge node is placed indoors, and is used to receive data from the voltage unit and the current unit and process the data according to the above method; the display end is used to display the edge node analysis results.

[0108] Specifically, the voltage unit and the current unit use wireless short-distance transmission to send data to the edge node. The edge node has two major functions: 1) complex calculation parameter preprocessing function, sending the calculation results to the voltage unit and the current unit; 2) voltage and current unit data sending processing and analysis function; the edge computing node displays the analyzed data on the display end.

[0109] Specifically, the voltage unit is a coupled capacitive sensor, and the voltage monitoring schematic diagram is as follows: Figure 4As shown, the high and low voltage arms of the sensor are respectively composed of coupling capacitors between the sensor and the earth and between the sensor and the transmission line. The low voltage arm and the subsequent acquisition and processing circuits are located near the high voltage end to be measured, and are electrically isolated from the low voltage end. In actual engineering, the voltage unit proposed by the present invention can reduce the impact of the particularity of operation in high voltage and strong magnetic environment on the data collected by the monitoring terminal, thereby improving the timeliness and effectiveness of data collection.

[0110] The sensor and the post-stage acquisition and processing system are installed on the high-voltage conductor to be measured. The coupling capacitor C1 between the sensor metal sheet and the high-voltage conductor is the low-voltage arm capacitor, and the coupling capacitor C2 between the sensor metal sheet and the ground is the high-voltage arm capacitor. The device housing is a metal shielding shell with good conductivity, which has undergone special anti-corona treatment and has good waterproof and dustproof functions. The acquisition and processing circuit is installed in the metal shielding shell. After the data is collected and processed, it is sent to the edge node through short-distance transmission. The edge node processes the collected data and outputs the final result.

[0111] From the perspective of the sensor equivalent structure, the sensor is actually a pure capacitive sensor. To reduce the impact of high-frequency oscillation, a damping resistor R1 can be connected in series with the capacitor. The wire, metal shielding shell, and the grounding terminal of the acquisition circuit are connected at the same potential, and their potential is regarded as 0. Then the actual earth can be regarded as a high-potential conductor. At this time, the measurement principle diagram is as follows Figure 5 shown.

[0112] The end measurement takes impedance matching into consideration. At this time, the actual voltage division ratio is:

[0113]

[0114] C M is the capacitance of damping resistor R1 to ground.

[0115] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0116] A computer-readable storage medium may be a tangible device that can hold and store instructions used 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 computer-readable storage media (a 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 disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0117] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, 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 transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The 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 the computer-readable storage medium in each computing / processing device.

[0118] The computer program instructions for performing the operation 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 "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via 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., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for online monitoring of dielectric loss of a power transformer, characterized in that: include: Step 1: The monitoring terminal collects voltage data and current data, and sends the collected data together with the corresponding first time stamp to the edge node; Step 2: When the edge node determines that the first time scale is valid, the voltage data and the current data are used to calculate the dielectric loss angle under the first time scale by using the fast Fourier transform method, and the process proceeds to step 5; otherwise, the process proceeds to step 3; Step 3: When the edge node determines that the first time stamp is invalid, the edge node sends a command to the monitoring terminal to reacquire the voltage and current data. The monitoring terminal sends the reacquired voltage data and current data together with the corresponding second time stamp to the edge node, wherein the time interval between the first time stamp and the second time stamp is the shortest. When the edge node determines that the second time stamp is invalid, step 3 is repeated until the second time stamp is valid and step 4 is entered. Step 4, using the voltage data and current data corresponding to the second time scale, using the fast Fourier transform method to calculate the dielectric loss angle at the second time scale, and using the time interval between the first time scale and the second time scale to correct the dielectric loss angle at the second time scale to obtain the dielectric loss angle at the first time scale; Step 5: The edge node calculates the dielectric loss angles of the three mutual sensors at multiple time scales, and calculates the similarity of the dielectric loss angles of any two mutual sensors. When the two similarities corresponding to any mutual sensor are less than a set threshold, the mutual sensor is judged to be abnormal.

2. The method for online monitoring of dielectric loss of a power transformer according to claim 1, characterized in that: Step 1 includes: The monitoring terminal synchronously collects three-phase voltage and three-phase current; filters the three-phase voltage and three-phase current; and uses the fast Fourier transform method to collect voltage data and current data within the fundamental frequency range.

3. The method for online monitoring of dielectric loss of a power transformer according to claim 1, characterized in that: In step 2, whether the time stamp is valid is determined based on the bytes of the time stamp.

4. The method for online monitoring of dielectric loss of a power transformer according to claim 1, characterized in that: In step 3, the first time mark is t0, the second time mark is t1, and the two time marks satisfy t1-t0-k*0.02≤0, where k is a positive integer; when step 3 is repeated, k is selected starting from 1. When it is determined that the second time mark is also invalid, k is increased by 1 to determine a new second time mark, and so on, so that the time interval between the newly obtained second time mark and the first time mark is the shortest and valid.

5. The method for online monitoring of dielectric loss of a power transformer according to claim 3, characterized in that: In step 4, the dielectric loss angle at the second time scale is corrected using the time interval between the first time scale and the second time scale, and the dielectric loss angle at the first time scale is calculated using the following relationship: Δt=t1-t0-(k-1)×0.02 In the formula, is the dielectric loss angle at the first time scale, is the dielectric loss angle under the second time scale, and Δt is the time interval.

6. The method for online monitoring of dielectric loss of a power transformer according to claim 5, characterized in that: The dielectric loss angle at the first time scale obtained in step 4 is When , the dielectric loss angle under the first time scale is corrected according to the following relationship: In the formula, is the correction value of the dielectric loss angle under the first time scale, and n is taken to be satisfy A positive integer.

7. The method for online monitoring of dielectric loss of a power transformer according to claim 1, characterized in that: In step 5, the similarity of the dielectric loss angles of any two mutual inductors satisfies the following relationship: In the formula, ρ AB is the similarity of dielectric loss angles of mutual inductors A and B; ρ AC is the similarity of dielectric loss angles of mutual inductors A and C; ρ BC is the similarity of dielectric loss angles of mutual inductors B and C; The time scale is t i The dielectric loss angle of the mutual inductors A, B and C under the condition; are the average values ​​of dielectric loss angles of mutual inductors A, B, and C at multiple time scales; m is a positive integer, indicating the number of time scales; i is a positive integer, indicating the number of time scales t i Serial number, i = 1, 2, 3,…, m.

8. The method for online monitoring of dielectric loss of a power transformer according to claim 7, characterized in that: The two similarities corresponding to any mutual sensor are less than the set threshold When the mutual inductor is abnormal, include: like It is determined that mutual inductor A is abnormal; like It is determined that the mutual inductor B is abnormal; like It is determined that the C mutual inductor is abnormal.

9. The method for online monitoring of dielectric loss of a power transformer according to claim 8, characterized in that: like It is determined that all mutual sensors are normal.

10. The power transformer dielectric loss online monitoring system is characterized by: include: Monitoring terminals and edge nodes; A monitoring terminal is used to collect voltage data and current data, and send the collected data together with the corresponding first time stamp to the edge node; The edge node is used to determine whether the first time scale is valid, and then use the voltage data and current data to calculate the dielectric loss angle under the first time scale by using the fast Fourier transform method; When the edge node determines that the first time stamp is invalid, the edge node sends a command to the monitoring terminal to reacquire the voltage and current data, and the monitoring terminal sends the reacquired voltage data and current data together with the corresponding second time stamp to the edge node, where the time interval between the first time stamp and the second time stamp is the shortest; When the edge node determines that the second time scale is invalid, the above operation is repeated until the second time scale is valid. The voltage data and current data corresponding to the second time scale are used to calculate the dielectric loss angle under the second time scale by adopting the fast Fourier transform method. The dielectric loss angle under the second time scale is corrected by using the time interval between the first time scale and the second time scale to obtain the dielectric loss angle under the first time scale. The dielectric loss angle of the three-phase inductor under multiple time scales is calculated to calculate the similarity of the dielectric loss angles of any two mutual inductors. When the two similarities corresponding to any mutual inductor are less than the set threshold, the mutual inductor is judged to be abnormal.

11. The power transformer dielectric loss online monitoring system according to claim 10, characterized in that: The monitoring terminal includes a voltage unit installed on the line body and a current unit installed on the transformer grounding wire; Among them, the voltage unit is a coupled capacitance sensor. The high and low voltage arms of the sensor are respectively composed of coupling capacitances between the sensor and the earth and between the sensor and the transmission line. The low voltage arm and the subsequent acquisition and processing circuits are located near the high voltage end to be measured, forming electrical isolation from the low voltage end.

12. A terminal comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 9.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

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