Transformer digital relay based on oil pressure change feature recognition and method

Abstract

The invention discloses a transformer digital relay based on oil pressure change feature recognition and a method, and belongs to the field of power systems. The relay comprises a pressure acquisition module, a signal conditioning module, a digital core processing module and an execution control module. The pressure acquisition module is used for measuring transient oil pressure change characteristics in the transformer in real time and outputting analog signals. The signal conditioning module is used for receiving the analog signal output by the pressure acquisition module and processing the analog signal to obtain a standard digital signal; and the digital core processing module is used for performing feature calculation, logic judgment and start control decision according to the standard digital signal output by the signal conditioning module, and generating an execution signal. According to the relay, through constructing a high-precision pressure sensing link and real-time digital feature extraction and criterion logic, accurate identification of internal faults of an oil tank is realized, so that the defense capability and the operation safety level of the oil-immersed power transformer in extreme internal accidents are improved.

Description

Technical Field

[0001] This invention relates to the field of power systems, and more specifically to a digital relay and method for transformers based on oil pressure change characteristics identification. Background Technology

[0002] Oil-immersed transformers, as crucial main equipment in power systems, play a vital role in the reliable transmission and flexible distribution of electrical energy, as well as system safety. When a transformer experiences internal faults such as inter-turn short circuits, winding grounding, or arcing, transient pressure fluctuations occur in the internal oil medium. If the fast-acting oil pressure relay responds slowly or fails to operate, the fault energy will rapidly accumulate, potentially leading to localized deformation and cracking of the oil tank, and in severe cases, even explosions or fires. Conversely, if the relay protection malfunctions under normal fault conditions, it will cause unnecessary power outages and economic losses. Therefore, for high-voltage, large-capacity transformers, developing fast-acting, highly sensitive, and reliable internal fault oil pressure protection technology is of great significance.

[0003] During internal transformer faults, transient changes in oil pressure are a direct physical quantity reflecting the fault state. These characteristics include pressure rise amplitude, rise rate, waveform envelope, and pulsation pattern. These oil pressure change characteristics can reflect not only strong faults but also weak or early-stage faults. Relying solely on traditional electrical protection methods, such as overcurrent protection or differential protection, often fails to sensitively detect weak faults. The cumulative effect of fault oil pressure creates surges and localized high-pressure areas within the tank. These non-electrical characteristics can serve as important criteria for constructing fast-acting protection, improving the ability to identify internal faults and the reliability of operation.

[0004] Currently, most fast-acting hydraulic relays widely used in engineering adopt a mechanical structure, which senses changes in oil pressure and triggers a tripping action through mechanical structures such as pistons or springs. These mechanical relays have several shortcomings: First, mechanical inertia leads to limited response speed, potentially causing them to miss the optimal operating time; second, their sensitivity is easily affected by oil temperature, oil viscosity, and long-term mechanical wear, leading to the risk of failure to operate or malfunction; third, mechanical relays cannot analyze various characteristics of the oil pressure waveform, making it difficult to distinguish between internal faults and external disturbances, thus resulting in lower protection reliability. Therefore, traditional mechanical fast-acting hydraulic relays have significant limitations in the protection of modern large-capacity, high-voltage transformers. Summary of the Invention

[0005] To address the limitations in reliability and slow response to internal faults inherent in existing transformer fast-acting protection technologies, this invention proposes a digital fast-acting oil pressure relay for transformers based on oil pressure change feature recognition. By constructing a high-precision pressure sensing link and real-time digital feature extraction and criterion logic, it achieves accurate identification of internal faults in the oil tank, thereby improving the defense capability and operational safety level of oil-immersed power transformers in extreme internal accidents.

[0006] To achieve the above objectives, the present invention provides the following technical solution.

[0007] In a first aspect, the present invention provides a transformer digital relay based on oil pressure change feature recognition, characterized in that it comprises: a pressure acquisition module, a signal conditioning module, a digital core processing module, and an execution control module. The pressure acquisition module is used to measure the transient oil pressure change characteristics inside the transformer in real time and output analog signals; The signal conditioning module is used to receive the analog signal output by the pressure acquisition module and process the analog signal to obtain a standard digital signal. The digital core processing module is used to perform feature calculation, logical judgment, and start control decision based on the standard digital signal output by the signal conditioning module, and generate an execution signal. The execution control module is used to receive execution signals from the digital core processing module and to perform tripping or alarm control on the relay.

[0008] As a further improvement of the present invention, the digital core processing module includes a bus, a memory unit, an embedded microprocessor, a data acquisition and timing control unit, a feature recognition module, a judgment logic module, and a communication interface circuit; data between the memory unit, the embedded microprocessor, the data acquisition and timing control unit, the feature recognition module, the judgment logic module, and the communication interface circuit is transmitted through the bus; the bus includes a data bus, an address bus, and a control bus, realizing data exchange and operation control in the digital core processing module.

[0009] As a further improvement of the present invention, a digital input module is also included; the digital input module is used to acquire the transformer digital signal, process it, and output a high level or a low level, and then use the high level or low level as the input digital quantity of the digital core processing module.

[0010] As a further improvement of the present invention, a threshold setting module is also included; the threshold setting module is used to set the criterion threshold according to the operating conditions, transformer capacity and operating experience, and the setting result is used as the input digital quantity of the digital core processing module.

[0011] As a further improvement of the present invention, it also includes a communication and upper-level monitoring interface; the communication and upper-level monitoring interface is used to provide real-time oil pressure information and protection status to the monitoring system.

[0012] Secondly, the present invention provides a protection method for a transformer digital relay based on oil pressure change characteristic identification, comprising: The pressure acquisition module measures the changes in transformer oil pressure in real time and outputs an analog signal; The signal conditioning module receives the analog signal output from the pressure acquisition module, processes the signal, and outputs a standard digital signal. The digital core module receives the signal, processes and calculates the received data, obtains the real-time oil pressure change rate, compares the real-time oil pressure change rate with the change rate start threshold value, and if the comparison result meets the set requirements, the start flag is set and the system enters the fast-acting pre-start state. After entering the fast-acting pre-start state, the transient pressure peak value is calculated, and the magnitude relationship between the current transient pressure peak value and the protection threshold value of the digital fast-acting hydraulic relay, as well as the instantaneous oil pressure change rate and the change rate confirmation threshold, is determined to identify internal faults in the transformer tank. If a fault is detected inside the transformer tank, the control module will send a trip signal, and the entire system will reset and wait for resetting.

[0013] As a further improvement of the present invention, the digital core module receives a signal, processes and calculates the received data to obtain the real-time oil pressure change rate, including:

[0014] In the formula, This represents the instantaneous rate of change of oil pressure. This is the differential change in pressure; The time interval is the differential interval; This represents the oil pressure value at the current sampling point; This is the oil pressure value from the previous sampling point; This is the current sampling time; This refers to the previous sampling time.

[0015] As a further improvement of the present invention, the comparison of the real-time oil pressure change rate and the change rate start threshold value, if the comparison result meets the set requirements, the start flag bit includes: Compare the real-time oil pressure change rate with the change rate start-up threshold value; the comparison result must meet the following requirements. When the start flag is set, the system enters the quick-start pre-start state; In the formula, This represents the instantaneous rate of change of oil pressure. The threshold value for the rate of change.

[0016] As a further improvement of the present invention, after entering the rapid pre-start state, calculating the transient pressure peak includes:

[0017] In the formula, The transient pressure peak value at time t; T is the data window length; f is the signal acquisition frequency of the sampling module; This is the oil pressure value at the current sampling point.

[0018] As a further improvement of the present invention, the step of determining the magnitude relationship between the current instantaneous pressure peak value and the digital fast-acting hydraulic relay protection threshold value, and between the instantaneous oil pressure change rate and the change rate confirmation threshold, to identify internal faults in the transformer tank, includes: The magnitude of the difference between the current transient pressure peak value and the protection threshold value of the digital slew rate hydraulic relay must meet the following requirements. ; The magnitude of the difference between the instantaneous oil pressure change rate and the change rate confirmation threshold ; when If both conditions are met simultaneously, it is confirmed that there is a fault inside the transformer tank.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The relay provided in this application constructs a high-precision pressure sensing link. The pressure acquisition module can measure the transient oil pressure changes inside the transformer in real time and accurately, providing a reliable data foundation for subsequent processing. The signal conditioning module performs fine processing on the acquired analog signals, converting them into standard digital signals, effectively reducing interference and errors in signal transmission and processing. The digital core processing module performs feature calculations, logical judgments, and start-up control decisions based on these high-quality digital signals. Its powerful digital processing capabilities ensure the accuracy and timeliness of decisions, reduce the probability of malfunctions and failures to operate, improve operational reliability, and provide a solid guarantee for the stable operation of the power system. This application, through real-time digital feature extraction and criterion logic, can quickly capture subtle changes in the oil pressure inside the transformer. The digital core processing module completes complex calculations and logical judgments instantly, rapidly generating execution signals. After receiving the signal, the execution control module immediately trips or alarms the relay. The entire process is highly efficient and fast, greatly shortening the response time to internal faults. It can promptly cut off the fault source or issue an alarm in the early stages of a fault, effectively preventing further spread of the fault and avoiding the deterioration of the accident. Thus, accurate identification of faults inside the oil tank is achieved. By deeply analyzing and accurately judging the characteristics of oil pressure changes, different types of internal faults can be distinguished, providing maintenance personnel with detailed fault information. This helps to quickly locate the fault location, analyze the cause of the fault, and thus take targeted maintenance measures, improve maintenance efficiency, and reduce power outage time.

[0020] Furthermore, this application employs an adjustable threshold structure and software configurability, allowing for flexible setting of criterion parameters based on on-site operating conditions and transformer structural differences. This adapts to transformer equipment with varying capacities, voltage levels, insulation structures, and tank shapes. It also supports on-demand upgrades and functional expansions, providing a sustainable development platform for intelligent transformer protection systems and broadening their engineering applicability. Linkage control is achieved through digital output and communication with the upper-level system, enabling real-time uploading of pressure waveforms, characteristic curves, criterion action status, and historical records, supporting online analysis and maintenance decision-making management. Compared to traditional fast-acting protection that only outputs switching quantities and cannot provide behavioral evidence, this invention supports complete recording and source analysis of the fault process, providing a high-value data source for transformer condition monitoring systems. Attached Figure Description

[0021] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. In the drawings: Figure 1 This is a schematic diagram of the structure of a transformer digital relay based on oil pressure change feature recognition according to the present invention.

[0022] Figure 2This is a flowchart of a protection method for a transformer digital relay based on oil pressure change feature identification according to the present invention. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] To address the limitations of existing transformer fast-acting protection technologies, such as limited operational reliability and slow response to internal faults, this invention proposes a digital fast-acting hydraulic relay for transformers based on hydraulic pressure change characteristic recognition. Figure 1 As shown, it includes a pressure acquisition module, a signal conditioning module, a digital input module, a digital core processing module, a threshold setting and storage module, an execution control module, a communication and upper-level monitoring interface, and an intelligent interaction module. The modules interact and operate collaboratively with each other through an internal communication bus.

[0026] The pressure acquisition module is connected to the signal conditioning module, while the threshold setting and storage module, the signal conditioning module, and the digital input module are all connected to the digital core processing module.

[0027] The pressure acquisition module is used to measure the transient oil pressure change characteristics inside the transformer in real time at high speed and output the corresponding analog voltage / current signal. The pressure acquisition module consists of a piezoresistive high-frequency dynamic pressure sensor, a sealed mounting structure and communication cables.

[0028] The signal conditioning module receives the analog voltage / current signal output from the pressure acquisition module and processes the signal, including suppressing noise, reducing mechanical vibration interference, and enhancing key change characteristics. Then, it converts the analog signal into a standard digital signal that can be recognized by the digital core processing module through high-speed sampling.

[0029] The digital input module is used to acquire the relevant digital signals that the transformer needs to know, and outputs them as high level 1 or low level 0 as input digital quantities for the digital core processing module.

[0030] The threshold setting module allows users to set the criterion threshold based on operating conditions, transformer capacity, or operating experience. It also serves as the input digital quantity for the digital core processing module, assisting its internal logic judgment.

[0031] After receiving the standard digital signal from the signal conditioning module, the digital core processing module undertakes the functions of feature calculation, logic judgment and start control, thereby realizing the relay protection function, and is the core functional unit of this invention.

[0032] The execution control module outputs trip or alarm control signals based on the final judgment criteria.

[0033] The communication and upper-level monitoring interface provides real-time oil pressure information and protection status to the monitoring system.

[0034] The intelligent interaction module allows users to establish information communication with the protection device.

[0035] Specifically, the pressure acquisition module is installed on the outer side of the transformer tank wall, with a mechanical fixing structure ensuring reliable sealing, and is connected to the signal conditioning module via an anti-interference shielded communication cable. The pressure acquisition module contains a piezoresistive high-frequency dynamic pressure sensor.

[0036] The piezoresistive high-frequency dynamic pressure sensor is used for high-speed measurement of local transient pressure waveforms caused by faults within the oil tank cavity. Its output is an analog voltage or current signal corresponding to the amplitude of the pressure change. This sensor features short response time, wide frequency response range, and excellent oil resistance, and can effectively capture rapid pressure increases caused by internal electric arcs, short-circuit impacts, or mechanical damage.

[0037] The signal conditioning module receives the output signal from the pressure acquisition module and optimizes and converts it to generate a standard digital signal. Internally, the signal conditioning module includes terminals, a signal conditioning circuit, a low-pass filter, a signal sampling circuit, and an analog-to-digital (A / D) converter circuit. These units are connected sequentially according to the signal transmission order.

[0038] The signal conditioning circuit is used to perform primary amplification and protection on the weak electrical signal output by the pressure acquisition module, thereby increasing the signal amplitude and suppressing noise. The low-pass filter is used to filter out high-frequency noise components such as electromagnetic interference and mechanical vibration, and to obtain the true and effective oil pressure change characteristics. The signal sampling circuit is used to stably acquire the filtered analog signal. The analog-to-digital A / D conversion circuit is used to convert the analog signal into a digital signal and send it to the digital core processing module for further calculation and fault diagnosis.

[0039] The signal conditioning module receives the output signal from the pressure acquisition module through the terminal block. The signal conditioning circuit optimizes the output signal from the pressure acquisition module to obtain an analog voltage signal. The analog voltage signal is filtered out by a low-pass filter to remove high-frequency noise, resulting in a clean analog voltage. The signal sampling circuit captures the clean analog voltage at fixed time intervals to obtain a discrete-time analog voltage. The analog-to-digital converter (A / D) converts the discrete-time analog voltage into binary data and outputs a standard digital signal.

[0040] Digital core processing module, such as Figure 1 As shown, it consists of a bus, a memory unit, an embedded microprocessor, a data acquisition and timing control unit, a feature recognition module, a judgment logic module, and a communication interface circuit, and realizes internal data access and coordination control through the bus.

[0041] The bus includes a data bus, an address bus, and a control bus, which realizes data exchange and operation control in the digital core processing module; the embedded microprocessor is used to execute oil pressure signal processing algorithms and protection logic decisions based on standard data signals, providing computing power for real-time extraction of oil pressure change characteristics; the memory unit is used to store setting parameters, running programs, and historical sampling data; the data acquisition and timing control unit is used to synchronously sample and control the sampling window of the pressure signal after analog-to-digital conversion, ensuring the timing accuracy of the rate of change calculation, and providing timing for interrupt and protection delay actions; the feature recognition module is used to complete the real-time calculation and extraction of transient pressure peak and oil pressure change rate; the criterion logic unit is used to compare real-time data with thresholds, and execute fault identification and protection start-up decisions according to the dual-criterion judgment mechanism to realize dual-criterion protection judgment; the communication interface circuit is used for uploading and managing the device's operating status, setting parameters, and recorded data.

[0042] The threshold tuning and storage module supports setting the startup threshold via software. Confirmation threshold and peak pressure threshold The settings can be configured by the user according to the actual operating conditions and stored in non-volatile memory to ensure that the parameters are maintained when the equipment is powered off for a long time.

[0043] The execution control module consists of opto-isolated devices and output relays. Its function is to drive the back-end circuit breaker or alarm contacts according to the trip command output by the judgment logic module, and to achieve electrical isolation between the control side and the high-voltage side through opto-isolation, thereby improving the operational safety and electromagnetic interference resistance of the device.

[0044] The communication and upper-level monitoring interface adopts the standard industrial communication protocol to realize data interaction with the monitoring system. It can upload information such as pressure waveforms, characteristic values, and criterion status, which facilitates status monitoring, event recording, and operation analysis.

[0045] The intelligent interaction module includes indicator lights, displays, and buttons, which are used to display the operating status locally, query parameters, and facilitate human-machine interaction. If necessary, printing or information storage functions can be integrated to support accident tracing.

[0046] The digital input module is used to acquire relevant digital signals that need to be known and output them as a high level 1 or a low level 0 as the input digital quantity of the digital core processing module.

[0047] The second objective of this invention is to provide a protection method for a transformer digital relay based on oil pressure change characteristic identification, such as... Figure 2 As shown, it includes: S1: After being put into operation, the digital fast-acting hydraulic relay first enters the power-on reset and system initialization process.

[0048] After the device is powered on, it automatically executes a self-test procedure, including checking the operating status of the digital core processing unit, signal conditioning module, sensor channel, and intelligent interaction module. If any unit fails the self-test, an alarm message is output and the protection action is locked, waiting for manual handling. If the self-test passes, the system enters the data acquisition initialization stage.

[0049] Subsequently, the data acquisition and timing control unit initiates a timing sampling interrupt, and the digital core processing module buffers and performs preliminary detection on the sampled data.

[0050] Before the sampled data has accumulated to the set data window, the protection function remains locked to avoid false triggering caused by fluctuations during the power-on process; once the sampled data reaches the specified buffer amount, the system unlocks the protection function and enters the main loop monitoring process.

[0051] S2: During the main cycle monitoring process, the pressure acquisition module measures the change characteristics of transformer oil pressure in real time and outputs the corresponding analog voltage / current signal; the signal conditioning module receives the analog voltage / current signal output by the pressure acquisition module, processes it, and outputs a standard digital signal that the digital core processing module can recognize; after receiving the signal, the digital core module temporarily locks the protection function and waits for the sampling data buffer to store one to two cycles of data before unlocking the protection function.

[0052] During the main circulation monitoring process, the digital core processing module collects and updates the oil pressure signal in real time at a preset sampling frequency, while monitoring the equipment operation mode, whether the threshold setting parameters have changed, and the status of the flag bit.

[0053] If all devices are functioning normally and successfully obtain real-time signal results, the system will begin judging the pre-start conditions; if any device or signal status is abnormal, the corresponding self-recovery or debugging process will be performed, and the current main loop detection will end, re-entering the initialization step.

[0054] S3: The digital core processing module processes and calculates the received standard data signal, and obtains the real-time oil pressure change rate through formula (1), that is, the rise speed of the oil pressure signal in a short time window; compares the current oil pressure change rate with the starting threshold K1, that is, determines whether the digital fast-acting oil pressure relay is started by judging whether formula (2) is true; When the collected oil pressure change meets the pre-start condition, i.e., formula (2) holds, the real-time change rate reaches the change rate start threshold value. The system will set the start flag and increase the sampling frequency to enter the pre-start judgment stage; if the conditions are not met, a new round of main loop detection process will be restarted.

[0055] If formula (2) holds true, that is, when the rate of change reaches the set threshold, it is considered that there may be abnormal energy injection or early fault characteristics inside the transformer tank. The start flag is activated, the system enters the "fast start state" and enters S4.

[0056] (1) (2) In the formula, This represents the instantaneous rate of change of oil pressure. This is the differential change in pressure; The time interval is the differential interval; This represents the oil pressure value at the current sampling point; This is the oil pressure value from the previous sampling point; This is the current sampling time; This refers to the previous sampling time. The threshold value for the rate of change.

[0057] S4: After entering the rapid pre-start state, the embedded microprocessor in the digital core processing module immediately increases the sampling frequency and uses formula (3) to further calculate the transient pressure peak P. peak Simultaneously determine the peak transient pressure P at time t. peak and startup threshold P st The magnitude relationship between the values ​​of the oil pressure change rate and the starting threshold K2 is used to identify internal faults in the transformer tank by judging whether formula (4) is true. If formula (4) is true, a trip signal is issued, the entire protection system is reset, and manual reset is required.

[0058] (3) In the formula, T is the data window length; f is the signal acquisition frequency of the sampling module; This represents the peak transient pressure at time t.

[0059] (4) In the formula, This refers to the protection threshold value for digital slew hydraulic relays. A threshold is established for the rate of change.

[0060] During the pre-start-up phase, the digital core processing module calculates the transient pressure peak value based on the new sampling window, and combines the pressure change rate result with the protection threshold value of the digital fast-acting hydraulic relay. and the threshold for repeated confirmation of rate of change Make a joint judgment based on the criteria.

[0061] When formula (4) is true, it is assumed that there is rapid energy injection or strong pressure impact inside the transformer tank, and the system immediately outputs a trip control command; at the same time, the upper-level monitoring interface records the action data and uploads relevant parameters and waveforms for event backtracking analysis.

[0062] After the operation is completed, the device automatically resets and enters the waiting reset phase.

[0063] If formula (4) is not valid during the pre-start determination process, it is determined to be an ineffective trigger caused by disturbance or non-fault pressure wave. The system cancels the start flag and exits the pre-start state, returning to the normal monitoring mode.

[0064] In formula (4), This system is used to repeatedly confirm the rate of change condition, and simultaneously determines whether to trip by checking if the transient pressure peak reaches a set threshold. If the rate of change is triggered but the peak does not reach the confirmation threshold, the system automatically exits the first-level pre-start state, assuming the pressure disturbance is caused by external interference, load disturbance, or non-fault factors. If both conditions are met, it is considered that a strong pressure surge sufficient to threaten equipment safety has occurred inside the tank, which can be reliably determined as a serious internal fault, and a trip command is issued. This dual-feature joint criterion effectively avoids false tripping caused by non-fault factors such as external impacts, thereby effectively improving the selectivity and safety of the protection.

[0065] In summary, the digital fast-acting hydraulic relay based on oil pressure change feature recognition proposed in this invention achieves rapid response and accurate identification of strong pressure disturbances inside the transformer tank by constructing a pressure sensing link, a fully digital signal processing architecture, and a dual-feature joint criterion mechanism. This protection device can extract key pressure waveform features and make protection action decisions in the early stages of a fault, effectively shortening the response delay of traditional mechanical protection and significantly improving the efficiency of clearing internal faults before they worsen.

[0066] The present invention uses a high-frequency dynamic pressure sensing method to measure the transient pressure change of the fuel tank wall in real time. Traditional mechanical quick-acting protection relies on the transmission of a pressure cavity, and its response speed is greatly affected by the structural inertia and the oil flow coupling characteristics, making it difficult to accurately record the millisecond-level pressure mutation process. The high-frequency sensor adopted by the present invention can directly sense the rise of the transient pressure waveform, achieve rapid identification of the most critical protection moment at the initial stage of the fault, significantly reduce the action delay, and improve the protection response ability. Secondly, the present invention realizes a fully digital signal acquisition and processing link, which does not rely on mechanical contacts and analog control links from the sensing end to the criterion decision-making, avoiding the performance degradation problems caused by material aging, fatigue wear, and insulating oil pollution in the traditional structure. The digital implementation method has the characteristics of high long-term stability and strong environmental adaptability, and can maintain the consistency of the criterion action characteristics under different operating conditions, solving the problems of serious setting point drift and easy misoperation of traditional mechanical relays after long-term operation. Finally, the dual-criterion identification mechanism of transient peak characteristics and pressure change rate proposed by the present invention jointly judges the amplitude characteristics and dynamic change characteristics of the pressure waveform, effectively suppressing the misoperation risk caused by non-fault oil pressure waves such as pump switching, external vibration, and traffic disturbance while maintaining high sensitivity. Compared with the methods based on single pressure thresholds or empirical setting values in the prior art, the dual-criterion structure of the present invention has obvious anti-interference advantages and is applicable to complex on-site operating conditions, thus ensuring the selectivity and reliability of protection actions.

[0067] The present invention flexibly sets the criterion parameters by adopting a tunable threshold structure and a software-configurable method, combined with on-site operating conditions and transformer structure differences, and can adapt to transformer equipment with different capacities, voltage levels, insulation structures, and fuel tank shapes; and supports later on-demand upgrades and function expansions, providing a sustainable development platform for intelligent transformer protection systems and expanding the scope of engineering applications. The linkage control is realized by means of digital output and communication with the upper system, and the pressure waveform, characteristic quantity curve, criterion action state, and historical records can be uploaded in real time, supporting online analysis and operation and maintenance decision management. Compared with the problem that traditional quick-acting protection only outputs switch quantities and cannot provide behavioral basis, the present invention supports the complete recording and traceability analysis of the fault process, providing a high-value data source for the transformer condition monitoring system.

[0068] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

[0069] The above content provides a further detailed description of the present invention. It should not be construed that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A transformer digital relay based on oil pressure change characteristic recognition, characterized in that, include: Pressure acquisition module, signal conditioning module, digital core processing module, and execution control module: The pressure acquisition module is used to measure the transient oil pressure change characteristics inside the transformer in real time and output analog signals; The signal conditioning module is used to receive the analog signal output by the pressure acquisition module and process the analog signal to obtain a standard digital signal. The digital core processing module is used to perform feature calculation, logical judgment, and start control decision based on the standard digital signal output by the signal conditioning module, and generate an execution signal. The execution control module is used to receive execution signals from the digital core processing module and to perform tripping or alarm control on the relay.

2. A transformer digital relay based on oil pressure change feature identification according to claim 1, characterized in that, The digital core processing module includes a bus, a memory unit, an embedded microprocessor, a data acquisition and timing control unit, a feature recognition module, a judgment logic module, and a communication interface circuit. Data between the memory unit, the embedded microprocessor, the data acquisition and timing control unit, the feature recognition module, the judgment logic module, and the communication interface circuit is transmitted through the bus. The bus includes a data bus, an address bus, and a control bus, which enables data exchange and operation control in the digital core processing module.

3. A transformer digital relay based on oil pressure change feature recognition according to claim 1, characterized in that, It also includes a digital input module; The digital input module is used to acquire and process the transformer's digital input signals, outputting either a high or low level, which is then used as the input digital quantity for the digital core processing module.

4. A transformer digital relay based on oil pressure change feature identification according to claim 1, characterized in that, It also includes a threshold tuning module; The threshold setting module is used to set the criterion threshold according to the operating conditions, transformer capacity and operating experience. The setting result is used as the input digital quantity of the digital core processing module.

5. A transformer digital relay based on oil pressure change feature identification according to claim 1, characterized in that, It also includes communication and upper-level monitoring interfaces; The communication and upper-level monitoring interface is used to provide real-time oil pressure information and protection status to the monitoring system.

6. A protection method for a transformer digital relay based on oil pressure change characteristic identification, characterized in that, A transformer digital relay based on oil pressure change feature identification as described in any one of claims 1-5 includes: The pressure acquisition module measures the changes in transformer oil pressure in real time and outputs an analog signal; The signal conditioning module receives the analog signal output from the pressure acquisition module, processes the signal, and outputs a standard digital signal. The digital core module receives the signal, processes and calculates the received data, obtains the real-time oil pressure change rate, compares the real-time oil pressure change rate with the change rate start threshold value, and if the comparison result meets the set requirements, the start flag is set and the system enters the fast-acting pre-start state. After entering the fast-acting pre-start state, the transient pressure peak value is calculated, and the magnitude relationship between the current transient pressure peak value and the protection threshold value of the digital fast-acting hydraulic relay, as well as the instantaneous oil pressure change rate and the change rate confirmation threshold, is determined to identify internal faults in the transformer tank. If a fault is detected inside the transformer tank, the control module will send a trip signal, and the entire system will reset and wait for resetting.

7. The protection method for a transformer digital relay based on oil pressure change characteristic identification according to claim 6, characterized in that, The digital core module receives signals, processes and calculates the received data to obtain the real-time oil pressure change rate, including: In the formula, This represents the instantaneous rate of change of oil pressure. This is the differential change in pressure; The time interval is the differential interval; This represents the oil pressure value at the current sampling point; This is the oil pressure value from the previous sampling point; This is the current sampling time; This refers to the previous sampling time.

8. The protection method for a transformer digital relay based on oil pressure change feature identification according to claim 6, characterized in that, The comparison of real-time oil pressure change rate and change rate start threshold value, if the comparison result meets the set requirements, activates the start flag, including: Compare the real-time oil pressure change rate with the change rate start-up threshold value; the comparison result must meet the following requirements. When the start flag is set, the system enters the quick-start pre-start state; In the formula, This represents the instantaneous rate of change of oil pressure. The threshold value for the rate of change.

9. A protection method for a transformer digital relay based on oil pressure change characteristic identification according to claim 6, characterized in that, After entering the rapid pre-start state, the transient pressure peak value is calculated, including: In the formula, The transient pressure peak value at time t; T is the data window length; f is the signal acquisition frequency of the sampling module; This is the oil pressure value at the current sampling point.

10. A protection method for a transformer digital relay based on oil pressure change characteristic identification according to claim 6, characterized in that, The method of determining the magnitude relationship between the current instantaneous pressure peak value and the digital fast-acting hydraulic relay protection threshold, as well as between the instantaneous oil pressure change rate and the change rate confirmation threshold, to identify internal faults in the transformer tank includes: The magnitude of the difference between the current transient pressure peak value and the protection threshold value of the digital slew rate hydraulic relay must meet the following requirements. ; The magnitude of the difference between the instantaneous oil pressure change rate and the change rate confirmation threshold ; when If both conditions are met simultaneously, it is confirmed that there is a fault inside the transformer tank.

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