A method for evaluating and managing health of power equipment ultrasonic partial discharge state

Abstract

The application discloses a kind of power equipment ultrasonic partial discharge state evaluation and health management method, it is related to electrical equipment test technical field, comprising: to ultrasonic pulse waveform is carried out reverse gain compensation, obtains the real discharge intensity at partial discharge source;Real discharge intensity is converted into the single discharge damage of internal performance degradation degree of insulating structure;Single discharge damage and previous damage in historical operation process are accumulated and fused, and the total damage degree change process of power equipment insulating structure degradation evolution with time is constructed;And according to total damage degree change process, dynamic health index is obtained;Based on total damage degree change process and dynamic health index, the degradation trend of power equipment insulating structure to failure critical state is inferred;According to the remaining safe operation life of power equipment of degradation trend prediction, the fault prediction and hierarchical operation and maintenance management level of power equipment in whole life cycle are improved.

Description

Technical Field

[0001] This invention relates to the field of electrical equipment testing technology, and in particular to a method for ultrasonic partial discharge status assessment and health management of power equipment. Background Technology

[0002] With the continuous increase in power system capacity and operating voltage levels, the insulation reliability issues faced by power equipment during long-term operation are becoming increasingly prominent. Partial discharge, as an important physical phenomenon reflecting insulation defects and aging conditions of power equipment, has become a research focus in the fields of condition monitoring and operation and maintenance management. Ultrasonic partial discharge detection methods, due to their strong resistance to electromagnetic interference, applicability to enclosed structures, and ability to enable online monitoring, are widely used in the condition monitoring of transformers, gas-insulated equipment, and switchgear.

[0003] Existing ultrasonic-based partial discharge detection technologies do not fully consider the nonlinear physical attenuation of ultrasound waves along their propagation path in the complex insulating media of power equipment. For example, partial discharges of equal intensity at different spatial coordinates can cause misleading deviations in the amplitude of the signal received by the sensor due to differences in sound energy absorption and geometric diffusion. This spatial position effect makes it impossible for the detection results to objectively characterize the true microscopic losses within the insulating material. Consequently, current condition assessments can only provide instantaneous alarms and lack a quantitative characterization of the insulation degradation process, making it difficult to support fault prediction and health management decisions throughout the entire life cycle of power equipment. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method for ultrasonic partial discharge status assessment and health management of power equipment to solve the problem that inaccurate partial discharge assessment caused by differences in ultrasonic wave propagation affects status assessment and health management.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a method for ultrasonic partial discharge status assessment and health management of power equipment, comprising:

[0008] The ultrasonic pulse waveform generated by partial discharge is obtained to determine the spatial location of the partial discharge source inside the power equipment, and the spatial propagation path length of the partial discharge source is obtained based on the spatial location.

[0009] Based on the spatial propagation path length and the propagation attenuation characteristics of ultrasonic waves in the insulating medium, reverse gain compensation is performed on the ultrasonic pulse waveform to obtain the true discharge intensity at the partial discharge source.

[0010] The actual discharge intensity is converted into the amount of damage caused by a single discharge, which represents the degree of degradation of the internal performance of the insulation structure.

[0011] The damage from a single discharge is accumulated and merged with the damage from previous operations to construct the total damage rate change process of the insulation structure degradation of power equipment over time; and a dynamic health index is obtained based on the total damage rate change process.

[0012] Based on the total damage change process and dynamic health index, the degradation trend of the insulation structure of power equipment toward the critical failure state is inferred; the remaining safe operating life of the power equipment is predicted according to the degradation trend, and corresponding hierarchical operation and maintenance management decisions are generated based on the remaining safe operating life.

[0013] Preferably, the method for obtaining the spatial propagation path length of the partial discharge source includes:

[0014] Acquire ultrasonic pulse waveforms generated by partial discharge, synchronize different ultrasonic pulse waveforms, and extract the arrival time information corresponding to each ultrasonic pulse waveform;

[0015] The time difference between arrival times is combined with the spatial coordinates of each ultrasonic sensor; the spatial location of the partial discharge source inside the power equipment is inverted and calculated to obtain the three-dimensional spatial coordinates of the partial discharge source.

[0016] Calculate the straight-line distance between the three-dimensional spatial coordinates of the partial discharge source and the spatial coordinates of the ultrasonic sensor, and use the straight-line distance as the spatial propagation path length.

[0017] Preferably, the method for obtaining the true discharge intensity at the partial discharge source includes:

[0018] Based on the spatial propagation path length, the propagation attenuation characteristics of ultrasonic waves corresponding to the insulating medium type in the discharge region are determined.

[0019] For each ultrasonic pulse waveform, the spatial propagation path length and propagation attenuation characteristics are matched to obtain the amplitude attenuation of the ultrasonic pulse waveform during propagation under the spatial propagation path condition.

[0020] By performing reverse gain compensation on the ultrasonic pulse waveform according to the corresponding amplitude attenuation, the true discharge intensity corresponding to the partial discharge source is obtained.

[0021] Preferably, the method for obtaining the damage amount of a single discharge includes:

[0022] The actual discharge intensity is quantified to obtain the energy level corresponding to a single partial discharge event;

[0023] By combining energy levels with the material type and operating parameters of the insulation structure of power equipment, a correlation is established between the actual discharge intensity and the degree of performance degradation of the internal insulation structure.

[0024] Based on the correspondence, the energy level of a single partial discharge event is mapped to the single discharge damage quantity, which characterizes the degree of performance degradation of the internal insulation structure of power equipment.

[0025] Preferably, the method for constructing the total damage change process includes:

[0026] The sequence of past damage amounts formed during the historical operation of the insulation structure of power equipment is read from the historical insulation loss database in chronological order, and the most recently recorded past damage amount is used as the current cumulative benchmark.

[0027] Time weighting is applied to the sequence of past damage quantities, so that the past damage quantities closer to the current time are given high weights, and the past damage quantities farther from the current time are given low weights.

[0028] The current single discharge damage is incorporated into the previous damage sequence in chronological order; the most recent cumulative value is updated by accumulating it time by time to form a new cumulative record, and the new cumulative record is appended to the insulation loss history database by timestamp to generate the total damage change process over time.

[0029] Preferably, the method for obtaining the dynamic health index includes:

[0030] Extract the total damage state quantity corresponding to the current assessment moment from the process of total damage change;

[0031] The total damage state quantity is matched with the health state intervals divided based on the total damage distribution formed during historical operation to obtain the health quantification result of the current health level of the power equipment insulation structure;

[0032] The health quantification results are smoothed over time to obtain a dynamic health index that changes continuously over time.

[0033] Preferably, the inference of the degradation trend of the electrical equipment insulation structure towards the critical failure state includes:

[0034] The process of change in total damage degree is time-aligned with the dynamic health index to construct a joint state sequence of damage accumulation state and health level state at the same assessment time.

[0035] In the joint state sequence, the direction and magnitude of the change of the total damage state quantity at multiple consecutive evaluation times, as well as the direction and rate of change of the dynamic health index, are extracted to form a trend description sequence characterizing the evolution of insulation structure performance over time.

[0036] Based on the trend description sequence, we identify evolutionary segments where the total damage state quantity continuously increases and the dynamic health index continuously decreases, and use the identified evolutionary segments as candidate degradation segments for the insulation structure of power equipment to enter the accelerated deterioration stage.

[0037] Based on the overall evolution characteristics of the trend description sequence within the candidate degradation zone, the degradation trend type of the power equipment insulation structure performance deterioration from a slow evolution state to a critical failure state is determined and recorded in chronological order to form a degradation trend.

[0038] Preferably, the method for generating corresponding hierarchical operation and maintenance management decisions includes:

[0039] Based on the total damage change process and dynamic health index formed during historical operation, the criteria for determining whether the insulation structure of power equipment enters the critical failure state are established.

[0040] Based on the degradation trend, the evolution direction of the current total damage change process and dynamic health index is extended in the time dimension to predict the future moment when the total damage change process and dynamic health index reach the judgment benchmark. The time interval between this future moment and the current assessment moment is determined as the remaining safe operating life of the power equipment.

[0041] The remaining safe operating life is matched with the pre-divided remaining safe operating life level range to determine the corresponding operation and maintenance management level of the power equipment, and a hierarchical operation and maintenance management decision corresponding to the operation and maintenance management level is generated.

[0042] Preferably, the method for obtaining the amplitude attenuation includes:

[0043] The center frequency of each ultrasonic pulse waveform is extracted, and the corresponding attenuation coefficient per unit length is retrieved from the preset propagation attenuation characteristic database based on the center frequency; and linearly mapped with the corresponding spatial propagation path length to obtain the medium absorption attenuation value of each ultrasonic pulse waveform on the propagation path.

[0044] Based on the spatial propagation path length, the corresponding geometric diffusion factor is retrieved from the preset propagation attenuation characteristic database, and the geometric diffusion attenuation value corresponding to the spatial propagation path length is obtained by combining the spherical wave diffusion attenuation law.

[0045] The amplitude attenuation of the ultrasonic pulse waveform during propagation is obtained by summing the medium absorption attenuation value and the geometric diffusion attenuation value under the spatial propagation path condition.

[0046] Preferably, the method for constructing the joint state sequence includes:

[0047] Extract all original timestamps during the change of total damage level and all original timestamps in the dynamic health index; select the intersection interval, and establish a unified assessment time axis within the intersection interval according to a fixed time step;

[0048] The total damage change process and dynamic health index are mapped to a unified assessment time axis respectively; and the damage accumulation status and the health level status corresponding to each assessment time point on the unified assessment time axis are calculated.

[0049] By correlating the cumulative damage state with the health level state at the same assessment time according to the chronological order, a joint state sequence is constructed.

[0050] In a second aspect, the present invention provides a computer device including a memory and a processor, wherein the memory stores a computer program, wherein when the computer program is executed by the processor, it implements any step of the ultrasonic partial discharge status assessment and health management method for power equipment as described in the first aspect of the present invention.

[0051] Thirdly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, it implements any step of the ultrasonic partial discharge status assessment and health management method for power equipment as described in the first aspect of the present invention.

[0052] The beneficial effects of this invention are as follows: By utilizing the spatial propagation path length and insulation medium attenuation characteristics obtained through spatial positioning inversion to perform gain compensation on the ultrasonic pulse waveform, the signal distortion caused by propagation distance and medium differences is effectively corrected, improving the accuracy of partial discharge intensity assessment; the compensated true discharge intensity is converted into the damage amount of a single discharge, and the total damage degree change process over time is constructed, realizing a deep transformation from instantaneous feature extraction to the characterization of the intrinsic loss of the insulation structure, providing reliable data support for accurately inferring the trend of insulation degradation and predicting the remaining safe operating life, and improving the level of fault prediction and hierarchical operation and maintenance management of power equipment throughout its entire life cycle. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a flowchart of the ultrasonic partial discharge status assessment and health management method for power equipment in this invention.

[0055] Figure 2This is a flowchart for obtaining the actual discharge intensity in this invention.

[0056] Figure 3 This is a flowchart of the process for obtaining the dynamic health index in this invention.

[0057] Figure 4 This is a flowchart for generating hierarchical operation and maintenance management decisions in this invention. Detailed Implementation

[0058] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0059] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0060] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0061] Reference Figure 1 , Figure 2 , Figure 3 and Figure 4 As one embodiment of the present invention, this embodiment provides a method for ultrasonic partial discharge status assessment and health management of power equipment, including the following steps:

[0062] Methods for obtaining the spatial propagation path length of a partial discharge source include:

[0063] The ultrasonic pulse waveform generated by partial discharge is acquired, and different ultrasonic pulse waveforms are synchronized to extract the arrival time information corresponding to each ultrasonic pulse waveform.

[0064] It should be noted that the ultrasonic pulse waveform generated by partial discharge is acquired by an ultrasonic sensor. A synchronous clock signal is used to align the time reference of multiple ultrasonic pulse waveforms received by ultrasonic sensors installed at different locations on the power equipment. Feature point identification is performed on each synchronized ultrasonic pulse waveform to find the first peak position or waveform initiation point where the amplitude exceeds a preset noise floor threshold. The corresponding time is determined as the arrival time information, and the arrival time information corresponding to each ultrasonic pulse waveform is extracted. For example, if the preset noise floor threshold is 50 millivolts, and the first ultrasonic pulse waveform is detected to exceed 50 millivolts at 100 microseconds, then the arrival time information corresponding to the first ultrasonic pulse waveform is extracted as 100 microseconds.

[0065] The time difference between arrival times is combined with the spatial coordinates of each ultrasonic sensor; the spatial location of the partial discharge source inside the power equipment is inverted and calculated to obtain the three-dimensional spatial coordinates of the partial discharge source.

[0066] It should be noted that, based on the arrival time information, one of the arrival time information is randomly selected as the reference time, and the arrival time information of other sources is subtracted from the reference time to obtain the time difference relationship between multiple sets of arrival times. The time difference relationship between multiple sets of arrival times is then multiplied by the propagation speed of ultrasound in the insulating medium. The propagation speed of ultrasound in the insulating medium is derived from the experimentally measured speed and is converted into the relative distance difference between the partial discharge source and different ultrasonic sensors. A nonlinear equation system containing the unknown three-dimensional spatial coordinates of the partial discharge source and the spatial coordinates of each ultrasonic sensor is established. The least squares algorithm is used to perform coordinate iterative search in the three-dimensional space of the power equipment. In each iteration, the geometric distance from the unknown coordinate point to each ultrasonic sensor is calculated and the difference is obtained to obtain the calculated distance difference. The coordinate point that minimizes the sum of squared residuals between the calculated distance difference and the relative distance difference is searched. The searched coordinate point is determined as the spatial position of the partial discharge source inside the power equipment, and the three-dimensional spatial coordinates of the partial discharge source are obtained.

[0067] Calculate the straight-line distance between the three-dimensional spatial coordinates of the partial discharge source and the spatial coordinates of the ultrasonic sensor, and use the straight-line distance as the spatial propagation path length.

[0068] It should be noted that, using the Euclidean distance formula, the three-dimensional spatial coordinates of the local discharge source and the spatial coordinates of each ultrasonic sensor are substituted into the calculation to obtain the linear geometric distance between the two in three-dimensional space, and this geometric distance is determined as the spatial propagation path length.

[0069] Methods for obtaining the true discharge intensity at the partial discharge source include:

[0070] Based on the spatial propagation path length, the propagation attenuation characteristics of ultrasonic waves corresponding to the insulating medium type in the discharge region are determined.

[0071] It should be noted that, based on the spatial propagation path length and the spatial region where the partial discharge source is located in the internal structure diagram of the power equipment, the type of insulating medium filling the space between the partial discharge source and the ultrasonic sensor is identified; based on the identified insulating medium type, the corresponding propagation attenuation characteristic parameters are retrieved from the preset propagation attenuation characteristic database; the propagation attenuation characteristic parameters are characteristic indicators used to quantify the degree of energy loss of ultrasonic pulse waveforms with propagation distance in a specific insulating medium, including the unit length attenuation coefficient that varies with frequency and the geometric diffusion factor that describes the degree of beam diffusion, to determine the propagation attenuation characteristics of ultrasonic waves corresponding to the insulating medium type of the discharge region;

[0072] It should be noted that by changing the transmission frequency and propagation distance of the standard ultrasonic pulse source in an experimental device filled with different types of insulating media, the reduction ratio of the ultrasonic signal amplitude by different types of insulating media was measured and recorded. The attenuation coefficient per unit length and the geometric diffusion factor were calculated and stored according to the media type and frequency dimension to construct a preset propagation attenuation characteristic database.

[0073] The calculation method for the geometric diffusion factor is as follows: Based on the physical characteristic that ultrasonic pulse waveforms diffuse as spherical waves in a homogeneous medium, a reference distance is set (0.1 meters in the example). The diffusion factor of any spatial propagation path length relative to the reference distance is calculated and then logarithmically converted. The calculation process is as follows: Obtain the ratio of the spatial propagation path length to the reference distance, take the logarithm to base 10 of this ratio, and multiply it by 20 to obtain the geometric diffusion factor for the corresponding propagation distance.

[0074] The calculation method for the unit length attenuation coefficient is as follows: Specifically, subtract the geometric diffusion factor at the corresponding distance from the total amplitude reduction ratio at different propagation distances. The remaining amplitude loss is the dielectric absorption loss. Divide the dielectric absorption loss by the difference between the propagation distance and the reference distance to obtain the unit length attenuation coefficient of the insulating dielectric type at the corresponding frequency.

[0075] For each ultrasonic pulse waveform, the spatial propagation path length and propagation attenuation characteristics are matched to obtain the amplitude attenuation of the ultrasonic pulse waveform during propagation under the spatial propagation path conditions.

[0076] It should be noted that, for each ultrasonic pulse waveform, based on the identified insulating medium type, the corresponding propagation attenuation characteristic parameters are retrieved from a preset propagation attenuation characteristic database; the extracted center frequency is used as an index to match the unit length attenuation coefficient at a specific frequency in the preset propagation attenuation characteristic database, and this coefficient is multiplied by the calculated spatial propagation path length to obtain the medium absorption attenuation value; simultaneously, based on the spatial propagation path length, the corresponding geometric diffusion factor is retrieved, and the geometric diffusion attenuation value is calculated; the medium absorption attenuation value and the geometric diffusion attenuation value are fused to obtain the amplitude attenuation of the ultrasonic pulse waveform during propagation under the spatial propagation path condition.

[0077] By performing reverse gain compensation on the ultrasonic pulse waveform according to the corresponding amplitude attenuation, the true discharge intensity corresponding to the partial discharge source is obtained.

[0078] Specifically, for each ultrasonic pulse waveform, the original maximum amplitude of the ultrasonic pulse waveform at the acquisition end is obtained. Combined with the amplitude attenuation of the ultrasonic pulse waveform during propagation under the spatial propagation path conditions, a reverse compensation gain value that is equal to the amplitude attenuation value but opposite in polarity is calculated. The reverse compensation gain value is superimposed on the original maximum amplitude value to offset the energy loss of the ultrasonic pulse waveform during propagation in the insulating medium, thus completing the reverse gain compensation of each ultrasonic pulse waveform according to the corresponding amplitude attenuation. Since the spatial propagation path lengths corresponding to ultrasonic sensors at different locations are different, by compensating each ultrasonic pulse waveform separately, the influence of spatial position differences on signal strength is eliminated, and the compensated amplitude is determined as the actual discharge intensity corresponding to the partial discharge source.

[0079] For example: the original maximum amplitude of the first ultrasonic pulse waveform is 60 dB, and the amplitude attenuation of the ultrasonic pulse waveform during propagation under the obtained spatial propagation path condition is 25 dB. Then, the reverse compensation gain value is calculated as positive 25 dB. The positive 25 dB is superimposed on 60 dB to obtain the actual discharge intensity corresponding to the partial discharge source, which is 85 dB.

[0080] Methods for obtaining the damage amount of a single discharge include:

[0081] The actual discharge intensity is quantified to obtain the energy level corresponding to a single partial discharge event.

[0082] It should be noted that, for the actual discharge intensity corresponding to the partial discharge source obtained, the peak value and pulse width of the actual discharge intensity are extracted, and the Joule thermal energy value carried by the ultrasonic pulse waveform is calculated using the acoustic-electric energy conversion formula to obtain the energy level corresponding to a single partial discharge event.

[0083] By combining energy levels with the material type and operating parameters of the insulation structure of power equipment, a correlation is established between the actual discharge intensity and the degree of internal performance degradation of the insulation structure.

[0084] It should be noted that the corresponding material type is determined based on the identified insulating medium type, and the current operating voltage and ambient temperature of the power equipment are obtained as operating condition parameters. The energy level is used as the independent variable, and the material type and operating condition parameters are used as correction coefficients. These are substituted into the insulation degradation energy efficiency formula for combined calculation, and the expression is as follows: ;in It is an effective damage energy density. It's the energy level. It is a material property correction factor. It is the working condition correction coefficient; by querying the material physical property table, the critical energy threshold for the physicochemical changes of different material types under operating conditions is obtained. The effective damage energy density is compared and analyzed with the critical energy threshold to determine the erosion ratio of the insulating material per unit energy and to establish the correspondence between the actual discharge intensity and the degree of internal performance degradation of the insulation structure.

[0085] Furthermore, the process for setting the material property correction coefficient and the operating condition correction coefficient is as follows: By conducting electrical aging tests on materials of different insulating media types, the rate of material performance degradation under unit discharge energy is measured. The obtained proportional unit energy damage ratio is stored in the material physical property table, and the material property correction coefficient is obtained by matching the identified material type. Simultaneously, the ratios of the real-time collected operating voltage and ambient temperature with the equipment's rated voltage and reference operating temperature are calculated to obtain the electrical stress multiple and thermal stress multiple. The electrical stress multiple and thermal stress multiple are multiplied to generate the operating condition correction coefficient for the environmental accelerated aging effect. For example, when the material type is insulating paper, the material property correction coefficient is taken as an example value of 0.85; when the ambient temperature is taken as an example value of 80°C and the operating voltage is taken as an example value of 110 kV, the operating condition correction coefficient is taken as an example value of 1.2.

[0086] Based on the correspondence, the energy level of a single partial discharge event is mapped to the single discharge damage quantity, which characterizes the degree of performance degradation of the internal insulation structure of power equipment.

[0087] It should be noted that, by utilizing the established correspondence between the actual discharge intensity and the degree of internal performance degradation of the insulation structure, the energy level of a single partial discharge event is input into the correspondence for conversion and calculation, and the percentage decrease in the microstructure damage volume or insulation performance index of the insulation material caused by a single discharge event is calculated; the calculated damage volume or percentage decrease is defined as the single discharge damage amount characterizing the degree of internal performance degradation of the insulation structure of power equipment.

[0088] Methods for constructing the total damage change process include:

[0089] The sequence of past damage amounts generated during the historical operation of the insulation structure of power equipment is read from the historical insulation loss database in chronological order, and the most recently recorded past damage amount is used as the current cumulative baseline.

[0090] It should be noted that the process involves accessing the historical insulation loss database and retrieving historical operation records under the target power equipment identifier. The process also involves extracting the sequence of past damage quantities formed during historical operation (the sequence of past damage quantities refers to a set of values ​​formed by single discharge damage quantities at various historical moments, arranged chronologically) according to the logic of timestamps from oldest to newest. The process then locates the last value corresponding to the timestamp in the sequence of past damage quantities and determines this last value as the current cumulative benchmark reflecting the current level of damage to the power equipment.

[0091] Time weighting is applied to the sequence of past damage quantities, so that past damage quantities closer to the current time are given high weights, and past damage quantities farther from the current time are given low weights.

[0092] It should be noted that the time difference between the timestamp corresponding to each past damage quantity in the past damage quantity sequence and the current assessment time is obtained. The time weight corresponding to each past damage quantity is calculated using an exponential decay function. The smaller the time difference of the past damage quantity, the higher the calculated time weight; the larger the time difference of the past damage quantity, the lower the calculated time weight. For example, if the time difference between the current assessment time and the timestamp of a certain past damage quantity is 24 hours, the time weight calculated by the exponential decay function is 0.95. If the time difference of another past damage quantity is 720 hours, the calculated time weight is decayed to 0.30.

[0093] The current single discharge damage is incorporated into the previous damage sequence in chronological order; the most recent cumulative value is updated by accumulating it time by time to form a new cumulative record, and the new cumulative record is appended to the insulation loss history database by timestamp to generate the total damage change process over time.

[0094] It should be noted that the calculated single-discharge damage amount is assigned the highest weight, with an example value of 1.0, and the single-discharge damage amount is incorporated into the previous damage amount sequence according to the timestamp of the current assessment time. The current cumulative benchmark and the single-discharge damage amount are accumulated and then combined with the previous damage amount sequence processed by time weight for global update. By multiplying each value in the previous damage amount sequence by the corresponding time weight and summing them, combined with the single-discharge damage amount, a new cumulative record reflecting the latest state of insulation degradation is formed. The new cumulative record, along with the corresponding timestamp, is synchronously appended to the insulation loss history database. Through continuous cyclic accumulation and record updates, the total damage degree change process characterizing the insulation degradation trend is generated.

[0095] Methods for obtaining dynamic health indices include:

[0096] Extract the total damage state quantity corresponding to the current assessment moment from the process of total damage change.

[0097] Specifically, from the process of generating changes in total damage, the numerical record corresponding to the timestamp of the current assessment time is retrieved, and this numerical record is determined as the total damage state quantity characterizing the cumulative damage level of the insulation structure of the power equipment at the current moment.

[0098] By matching the total damage state quantity with the health state intervals divided based on the total damage distribution formed during historical operation, the current health level of the power equipment insulation structure is obtained as a quantitative result.

[0099] Specifically, the total damage distribution based on historical operation is retrieved, and the total damage distribution is divided into multiple preset numerical intervals. Each numerical interval is defined as a different health level, namely excellent, good, medium, and poor, forming a health status interval. The extracted total damage status quantity is input into the health status interval for numerical comparison, and the specific numerical interval in which the total damage status quantity falls is identified. The health level corresponding to the specific numerical interval is determined as the health quantification result of the current health level of the power equipment insulation structure.

[0100] For example, the total damage distribution is divided into four health status intervals. The health level is defined as excellent when the total damage status quantity is in the range of 0 to 0.2, good when it is in the range of 0.2 to 0.5, medium when it is in the range of 0.5 to 0.8, and poor when it is in the range of 0.8 to 1.0. If the extracted total damage status quantity example value is 0.501 units of damage, and the total damage status quantity is identified as falling into the value interval of 0.5 to 0.8 through numerical comparison, then the corresponding health level "medium" is determined as the health quantification result of the current health level of the power equipment insulation structure.

[0101] The health quantification results are smoothed over time to obtain a dynamic health index that changes continuously over time.

[0102] It should be noted that a set of health quantification results is collected from the current assessment time and the time period prior to it within a preset time frame. The preset time frame refers to a time observation window set to eliminate the random interference of a single discharge. Multiple health quantification results are continuously extracted within this window to form a time series sample set. The arithmetic mean of all values ​​in the sample set is calculated using a moving average algorithm. The impact of the instantaneous discharge pulse on the assessment conclusion is offset by the mean calculation of the time series sample set, thus completing the time series smoothing processing of the health quantification results, thereby obtaining a dynamic health index that changes continuously over time. An example preset time frame of 24 hours is used.

[0103] The degradation trend of electrical equipment insulation structure towards the critical failure state can be inferred from the following:

[0104] The process of change in total damage degree is time-aligned with the dynamic health index to construct a joint state sequence of damage accumulation state and health level state at the same assessment time.

[0105] In the joint state sequence, the direction and magnitude of the change of the total damage state quantity at multiple consecutive evaluation times, as well as the direction and rate of change of the dynamic health index, are extracted to form a trend description sequence characterizing the evolution of insulation structure performance over time.

[0106] It should be noted that in the joint state sequence, the total damage state quantity between two adjacent assessment times is extracted. The numerical difference between adjacent times is calculated by performing a subtraction operation, and the absolute value of the numerical difference is determined as the change amplitude. At the same time, the sign of the numerical difference is extracted. If the sign is positive, the change direction is determined to be an increase in value; if the sign is negative, the change direction is determined to be a decrease in value. Simultaneously, the difference in the dynamic health index between adjacent assessment times is obtained and divided by the time step between the two assessment times to calculate the rate of change of the dynamic health index over time. This rate of change is determined as the rate of change and is used to quantify the deterioration or recovery speed of the health level. The numerical difference, change direction, and rate of change calculated at each time point are arranged in a matrix according to the time stamp order to form a trend description sequence characterizing the evolution of insulation structure performance over time.

[0107] Based on the trend description sequence, we identify evolutionary segments where the total damage state quantity continuously increases and the dynamic health index continuously decreases, and use the identified evolutionary segments as candidate degradation segments for the insulation structure of power equipment to enter the accelerated deterioration stage.

[0108] Based on the overall evolution characteristics of the trend description sequence within the candidate degradation zone, the degradation trend type of the power equipment insulation structure performance deterioration from a slow evolution state to a critical failure state is determined and recorded in chronological order to form a degradation trend.

[0109] It should be noted that the slope characteristics of the rate of change within the candidate degradation section are analyzed. If the absolute value of the rate of change increases exponentially with time, the degradation trend type is determined to be accelerated mutation type. If the rate of change remains constant, the degradation trend type is determined to be linear decay type. The determination results are correlated with the corresponding evolution time periods and recorded in chronological order to form a degradation trend reflecting the transition of the insulation structure of power equipment to the critical failure state.

[0110] The methods for generating corresponding hierarchical operation and maintenance management decisions include:

[0111] Based on the total damage change process and dynamic health index formed during historical operation, the criteria for determining whether the insulation structure of power equipment has entered the critical failure state are determined.

[0112] It should be noted that, based on the total damage change process and dynamic health index formed during historical operation, the historical peak value of total damage and the historical minimum value of health index are statistically analyzed at the moment when the power equipment experiences insulation breakdown or shutdown due to insulation failure. The average value of the historical peak value of total damage is determined as the total damage judgment benchmark, and the average value of the historical minimum value of health index is determined as the dynamic health index judgment benchmark, thereby forming the judgment benchmark for when the insulation structure of power equipment enters the critical state of failure.

[0113] Based on the degradation trend, the evolution direction of the current total damage change process and dynamic health index is extended in the time dimension to predict the future time when the total damage change process and dynamic health index reach the judgment benchmark. The time interval between this future time and the current assessment time is determined as the remaining safe operating life of the power equipment.

[0114] It should be noted that, based on the determined magnitude and rate of change in the degradation trend, a linear extrapolation algorithm is used, with the current assessment time as the starting point, and the total damage state quantity and dynamic health index at the current time as initial values, extending the trend along the time axis according to the magnitude and rate of change; by establishing a prediction equation with time as the independent variable, the predicted time when the total damage state quantity reaches the total damage judgment benchmark in the future evolution process, and the predicted time when the dynamic health index reaches the dynamic health index judgment benchmark in the future evolution process are calculated; from the above two predicted times, the date and time that arrives first on the time axis are selected and determined as the predicted failure time; by calculating the absolute duration between the predicted failure time and the current assessment time, the time difference between the two is obtained, and this time difference is determined as the remaining safe operating life of the power equipment;

[0115] It should be noted that the formula for calculating the remaining safe operating life is:

[0116] ;

[0117] in, It is the remaining safe operating life. It is the criterion for determining the total degree of damage. It is the total damage state quantity at the current moment. It is the rate of change of the total damage state quantity. It is the dynamic health index at the current moment. It is a benchmark for determining dynamic health index. It is the rate of change of the dynamic health index.

[0118] The remaining safe operating life is matched with the pre-divided remaining safe operating life level range to determine the corresponding operation and maintenance management level of the power equipment, and a hierarchical operation and maintenance management decision corresponding to the operation and maintenance management level is generated.

[0119] It should be noted that the remaining safe operating life is input into the remaining safe operating life level range for range matching. The standard for the remaining safe operating life level range is determined based on the importance of the power equipment and the power outage maintenance early warning cycle. Specifically, the standard is as follows: the range where the remaining safe operating life is greater than or equal to the preset first duration threshold is divided into a level three maintenance range, corresponding to normal maintenance decisions; the range where the remaining safe operating life is less than the first duration threshold but greater than or equal to the preset second duration threshold is divided into a level two maintenance range, corresponding to enhanced monitoring decisions; and the range where the remaining safe operating life is less than the second duration threshold is divided into a level one maintenance range, corresponding to emergency power outage maintenance decisions. It should be noted that the first duration threshold is 90 days in the example, and the second duration threshold is 30 days in the example.

[0120] Methods for obtaining amplitude attenuation include:

[0121] The center frequency of each ultrasonic pulse waveform is extracted, and the corresponding attenuation coefficient per unit length is retrieved from the preset propagation attenuation characteristic database based on the center frequency; and linearly mapped with the corresponding spatial propagation path length to obtain the medium absorption attenuation value of each ultrasonic pulse waveform on the propagation path.

[0122] It should be noted that the center frequency of each ultrasonic pulse waveform is extracted. The center frequency is obtained by calculating the frequency component corresponding to the peak value of the spectrum by performing a Fast Fourier Transform on the ultrasonic pulse waveform. Based on the extracted center frequency, the unit length attenuation coefficient matching the frequency and the currently identified insulating medium type is retrieved from a preset propagation attenuation characteristic database, using the frequency as the index. The retrieved unit length attenuation coefficient is then linearly multiplied by the corresponding spatial propagation path length to obtain the energy attenuation of each ultrasonic pulse waveform due to medium absorption along the propagation path, i.e., the medium absorption attenuation value.

[0123] Based on the spatial propagation path length, the corresponding geometric diffusion factor is retrieved from the preset propagation attenuation characteristic database, and the geometric diffusion attenuation value corresponding to the spatial propagation path length is obtained by combining the spherical wave diffusion attenuation law.

[0124] Specifically, based on the spatial propagation path length corresponding to each ultrasonic pulse waveform, the corresponding geometric diffusion factor is retrieved from a preset propagation attenuation characteristic database. The geometric diffusion factor is generated based on the spherical wave diffusion attenuation law. That is, with a preset reference distance (e.g., 0.1 meters) as the origin, the sound pressure attenuation factor of the spatial propagation path length relative to the reference distance is calculated and converted into a decibel value to obtain the geometric diffusion factor that quantifies the degree of beam diffusion.

[0125] The amplitude attenuation of the ultrasonic pulse waveform during propagation is obtained by summing the medium absorption attenuation value and the geometric diffusion attenuation value under the spatial propagation path condition.

[0126] Specifically, the calculated medium absorption attenuation value and geometric diffusion attenuation value are algebraically summed, and the sum of the two is the total amplitude attenuation of the ultrasonic pulse waveform during its propagation from the local discharge source to the sensor under its specific spatial propagation path.

[0127] Methods for constructing joint state sequences include:

[0128] Extract all original timestamps from the total damage change process and all original timestamps from the dynamic health index; select the intersection interval, and establish a unified assessment time axis within the intersection interval according to a fixed time step.

[0129] Specifically, all original timestamps are extracted during the change of total damage level, recording the moment of each damage accumulation update. Simultaneously, all original timestamps are extracted from the dynamic health index, recording the moment of each health index calculation output. These two sets of timestamps are compared, and the time range they cover is selected as the intersection interval. Within this intersection interval, a unified evaluation timeline is established according to a fixed time step (e.g., 1 hour in this example), so that each point on the timeline represents a regular evaluation moment.

[0130] The total damage change process and dynamic health index are mapped to a unified assessment time axis respectively; and the damage accumulation status and the health level status corresponding to each assessment time point on the unified assessment time axis are calculated.

[0131] It should be noted that the overall damage change process and the dynamic health index are mapped to a unified assessment time axis. For each assessment moment on the unified assessment time axis, the data point closest to its timestamp in the original data is found and assigned a value; if a data point directly corresponding to a certain assessment moment is lacking, linear interpolation is used to calculate the corresponding damage accumulation state or health level state based on the nearest data records before and after it.

[0132] By correlating the cumulative damage state with the health level state at the same assessment time according to the chronological order, a joint state sequence is constructed.

[0133] It should be noted that, in accordance with the chronological order of time on the unified assessment timeline, the cumulative damage state calculated at each assessment moment is paired with its corresponding health level state to form a one-to-one associated data pair; all these data pairs are arranged in chronological order to construct the joint state sequence.

[0134] This embodiment also provides a computer device applicable to the method for ultrasonic partial discharge status assessment and health management of power equipment, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the method for ultrasonic partial discharge status assessment and health management of power equipment as proposed in the above embodiment.

[0135] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0136] This embodiment also provides a storage medium storing a computer program. When executed by a processor, the program implements the method for assessing and managing the ultrasonic partial discharge status of power equipment as proposed in the above embodiments. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0137] In summary, this invention improves the accuracy of partial discharge intensity assessment by: using the spatial propagation path length and insulation medium attenuation characteristics obtained from spatial positioning inversion to perform gain compensation on ultrasonic pulse waveforms, effectively correcting signal distortion caused by propagation distance and medium differences; converting the compensated true discharge intensity into single discharge damage and constructing the total damage change process over time, thus achieving a deep transformation from instantaneous feature extraction to the characterization of the intrinsic loss of insulation structure. This provides reliable data support for accurately inferring the trend of insulation degradation and predicting the remaining safe operating life, and improves the level of fault prediction and hierarchical operation and maintenance management of power equipment throughout its entire life cycle.

[0138] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for assessing the ultrasonic partial discharge status and managing the health of power equipment, characterized in that, include: S1. Obtain the ultrasonic pulse waveform generated by partial discharge, determine the spatial location of the partial discharge source inside the power equipment, and obtain the spatial propagation path length of the partial discharge source based on the spatial location. S2. Based on the spatial propagation path length and the propagation attenuation characteristics of ultrasonic waves in the insulating medium, reverse gain compensation is performed on the ultrasonic pulse waveform to obtain the true discharge intensity at the partial discharge source. S3, converting the actual discharge intensity into the degree of internal performance degradation of the insulation structure in a single discharge; The method for obtaining the damage amount of a single discharge includes: The actual discharge intensity is quantified, and the Joule thermal energy value carried by the ultrasonic pulse waveform is calculated using the acoustic-electric energy conversion formula to obtain the energy level corresponding to a single partial discharge event. By combining the energy level with the material type and operating parameters of the power equipment insulation structure, and substituting them into the insulation decomposition energy efficiency formula for combined calculation, the expression is as follows: ;in It is an effective damage energy density. It's the energy level. It is a material property correction factor. It is the working condition correction coefficient; by comparing and analyzing the effective damage energy density with the critical energy threshold, the erosion ratio of the insulating material per unit energy is determined, and the correspondence between the actual discharge intensity and the degree of internal performance degradation of the insulation structure is established. Based on the correspondence, the energy level of a single partial discharge event is mapped to the single discharge damage quantity, which characterizes the degree of performance degradation of the internal insulation structure of power equipment. S4. Accumulate and merge the damage amount of a single discharge with the damage amount during historical operation to construct the total damage degree change process of the insulation structure degradation of power equipment over time; and obtain the dynamic health index based on the total damage degree change process. The method for constructing the total damage change process includes: The sequence of past damage amounts formed during the historical operation of the insulation structure of power equipment is read from the historical insulation loss database in chronological order, and the most recently recorded past damage amount is used as the current cumulative benchmark. Time weighting is applied to the sequence of past damage quantities, so that the past damage quantities closer to the current time are given high weights, and the past damage quantities farther from the current time are given low weights. The current single discharge damage amount is incorporated into the previous damage amount sequence in chronological order; the most recent cumulative value is updated by accumulating it one by one to form a new cumulative record, and the new cumulative record is appended to the insulation loss history database by timestamp to generate the total damage degree change process over time. The methods for obtaining the dynamic health index include: Extract the total damage state quantity corresponding to the current assessment moment from the process of total damage change; The total damage state quantity is matched with the health state intervals divided based on the total damage distribution formed during historical operation to obtain the health quantification result of the current health level of the power equipment insulation structure; The health quantification results are smoothed over time to obtain a dynamic health index that changes continuously over time. S5. Based on the total damage degree change process and dynamic health index, infer the degradation trend of the insulation structure of power equipment towards the critical failure state; predict the remaining safe operating life of power equipment according to the degradation trend, and generate corresponding hierarchical operation and maintenance management decisions based on the remaining safe operating life. The inferred degradation trend of the insulation structure of the power equipment towards the critical failure state includes: The process of change in total damage degree is time-aligned with the dynamic health index to construct a joint state sequence of damage accumulation state and health level state at the same assessment time. In the joint state sequence, the direction and magnitude of the change of the total damage state quantity at multiple consecutive evaluation times, as well as the direction and rate of change of the dynamic health index, are extracted to form a trend description sequence characterizing the evolution of insulation structure performance over time. Based on the trend description sequence, we identify evolutionary segments where the total damage state quantity continuously increases and the dynamic health index continuously decreases, and use the identified evolutionary segments as candidate degradation segments for the insulation structure of power equipment to enter the accelerated deterioration stage. Based on the overall evolution characteristics of the trend description sequence within the candidate degradation zone, the degradation trend type of the power equipment insulation structure performance deterioration from a slow evolution state to a critical failure state is determined and recorded in chronological order to form a degradation trend.

2. The method for ultrasonic partial discharge status assessment and health management of power equipment as described in claim 1, characterized in that, The method for obtaining the spatial propagation path length of the partial discharge source includes: Acquire ultrasonic pulse waveforms generated by partial discharge, synchronize different ultrasonic pulse waveforms, and extract the arrival time information corresponding to each ultrasonic pulse waveform; The time difference between arrival times is combined with the spatial coordinates of each ultrasonic sensor; the spatial location of the partial discharge source inside the power equipment is inverted and calculated to obtain the three-dimensional spatial coordinates of the partial discharge source. Calculate the straight-line distance between the three-dimensional spatial coordinates of the partial discharge source and the spatial coordinates of the ultrasonic sensor, and use the straight-line distance as the spatial propagation path length.

3. The method for ultrasonic partial discharge status assessment and health management of power equipment as described in claim 2, characterized in that, The method for obtaining the true discharge intensity at the partial discharge source includes: Based on the spatial propagation path length, the propagation attenuation characteristics of ultrasonic waves corresponding to the insulating medium type in the discharge region are determined. For each ultrasonic pulse waveform, the spatial propagation path length and propagation attenuation characteristics are matched to obtain the amplitude attenuation of the ultrasonic pulse waveform during propagation under the spatial propagation path condition. By performing reverse gain compensation on the ultrasonic pulse waveform according to the corresponding amplitude attenuation, the true discharge intensity corresponding to the partial discharge source is obtained.

4. The method for ultrasonic partial discharge status assessment and health management of power equipment as described in claim 1, characterized in that, The method for generating corresponding hierarchical operation and maintenance management decisions includes: Based on the total damage change process and dynamic health index formed during historical operation, the criteria for determining whether the insulation structure of power equipment enters the critical failure state are established. Based on the degradation trend, the evolution direction of the current total damage change process and dynamic health index is extended in the time dimension to predict the future moment when the total damage change process and dynamic health index reach the judgment benchmark. The time interval between this future moment and the current assessment moment is determined as the remaining safe operating life of the power equipment. The remaining safe operating life is matched with the pre-divided remaining safe operating life level range to determine the corresponding operation and maintenance management level of the power equipment, and a hierarchical operation and maintenance management decision corresponding to the operation and maintenance management level is generated.

5. The method for ultrasonic partial discharge status assessment and health management of power equipment as described in claim 3, characterized in that, The method for obtaining the amplitude attenuation includes: The center frequency of each ultrasonic pulse waveform is extracted, and the corresponding attenuation coefficient per unit length is retrieved from the preset propagation attenuation characteristic database based on the center frequency; and linearly mapped with the corresponding spatial propagation path length to obtain the medium absorption attenuation value of each ultrasonic pulse waveform on the propagation path. Based on the spatial propagation path length, the corresponding geometric diffusion factor is retrieved from the preset propagation attenuation characteristic database, and the geometric diffusion attenuation value corresponding to the spatial propagation path length is obtained by combining the spherical wave diffusion attenuation law. The amplitude attenuation of the ultrasonic pulse waveform during propagation is obtained by summing the medium absorption attenuation value and the geometric diffusion attenuation value under the spatial propagation path condition.

6. The method for ultrasonic partial discharge status assessment and health management of power equipment as described in claim 1, characterized in that, The method for constructing the joint state sequence includes: Extract all original timestamps during the change of total damage level and all original timestamps in the dynamic health index; select the intersection interval, and establish a unified assessment time axis within the intersection interval according to a fixed time step; The total damage change process and dynamic health index are mapped to a unified assessment time axis respectively; and the damage accumulation status and the health level status corresponding to each assessment time point on the unified assessment time axis are calculated. By correlating the cumulative damage state with the health level state at the same assessment time according to the chronological order, a joint state sequence is constructed.

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