Main transformer bushing CT 380V current rising device

Abstract

The invention provides a main transformer bushing CT 380V current rising device. The device comprises a three-phase four-wire socket, a first automatic winding and unwinding coil, a low-voltage circuit breaker, a second automatic winding and unwinding coil, a first electric energy quality monitoring module, a second electric energy quality monitoring module and a monitoring host. The three-phase four-wire socket is connected to a 380V maintenance power supply; and the first automatic winding and unwinding coil, the low-voltage circuit breaker and the second automatic winding and unwinding coil form a primary loop. The first monitoring module is connected with a primary line and used for measuring primary side operation data of the transformer. The second module is connected with the secondary side and used for measuring corresponding data. And the monitoring host is used for controlling the on-off of a primary loop, collecting data, judging the phase sequence of a power supply based on the primary side data and judging the health state of the transformer based on the secondary side data so as to verify the correctness of the main transformer bushing CT polarity and the transformation ratio. According to the invention, the verification precision and the test conclusion reliability can be significantly improved by collecting multi-dimensional data and monitoring standardized analysis of the host.

Description

Technical Field

[0001] This invention belongs to the field of power equipment testing technology, specifically relating to a 380V current boosting device for a main transformer bushing CT. Background Technology

[0002] In power systems, the main transformer is an extremely critical piece of equipment, and its protection system plays a vital role in ensuring the safe and stable operation of the power system. The main transformer bushing current transformer (CT), as an important component of the main transformer protection system, undertakes key tasks such as current detection and signal transmission, directly affecting the accuracy and reliability of the main transformer protection.

[0003] During the expansion of main transformers and the upgrading of protection systems for main transformers that have exceeded their service life, a current-increasing test is required on the zero-sequence bushing CTs and the high-voltage CTs (A, B, C, and D) of the main transformer to verify the correctness of the polarity and turns ratio of the main transformer bushing CTs. Currently, the industry commonly uses the 380V current-passing method for main transformer bushing CTs. Its core principle is to simulate the actual operating state of the main transformer, apply a three-phase positive-sequence AC voltage to the output side of the high-voltage bushing CT, and short-circuit it at the intermediate bushing and the low-voltage bus bridge (or after the low-voltage switchgear CT) to form a complete current loop. The polarity and turns ratio are determined by manually observing the magnitude and angle of the current on the primary and secondary sides.

[0004] However, in the existing main transformer bushing CT 380V current-carrying method test, the verification of CT polarity and turns ratio relies only on manual observation of the current magnitude and angle in a single dimension. It lacks multi-dimensional system monitoring and standardized analysis methods, which makes the verification process susceptible to external interference and difficult to fully reflect potential problems such as CT winding insulation status, core characteristics and grounding faults. Ultimately, this results in technical defects such as insufficient verification accuracy and low reliability of test conclusions. Summary of the Invention

[0005] In view of this, the present invention provides a main transformer bushing CT 380V current boosting device, which aims to solve the above-mentioned shortcomings of the existing main transformer bushing CT 380V current carrying method test.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] A 380V current boosting device for a main transformer bushing CT, comprising:

[0008] Three-phase four-wire socket, first automatic take-up and release coil, low-voltage circuit breaker, second automatic take-up and release coil, first power quality monitoring module, second power quality monitoring module and monitoring host;

[0009] A three-phase four-wire socket is used to connect a 380V maintenance power supply.

[0010] One end of the first automatic take-up and release coil is connected to a three-phase four-wire socket for taking up and releasing the built-in cable;

[0011] One end of the low-voltage circuit breaker is connected to the other end of the first automatic take-up coil to control the on / off of the primary circuit;

[0012] One end of the second automatic take-up coil is connected to the other end of the low-voltage circuit breaker, and the other end of the second automatic take-up coil is connected to the primary side circuit of the transformer for taking up and releasing the built-in cable to realize the connection between the primary line and the primary side circuit of the transformer.

[0013] The first power quality monitoring module is connected to the primary circuit and is used to monitor the operating status data of the primary circuit of the transformer.

[0014] The second power quality monitoring module is connected to the secondary circuit of the transformer and is used to monitor the operating status data of the secondary circuit of the transformer.

[0015] The monitoring host is electrically connected to the first automatic take-up coil, the low-voltage circuit breaker, the second automatic take-up coil, and the first power quality monitoring module, and is wirelessly connected to the second power quality monitoring module.

[0016] The monitoring host is used to control the cable winding and unwinding of the first and second automatic winding and unwinding coils, control the on / off state of the low-voltage circuit breaker, collect the first operating status data of the first power quality monitoring module and receive the second operating status data of the second power quality monitoring module, determine the phase sequence of the 380V maintenance power supply based on the first operating status data, and determine the health status of the transformer based on the second operating status data, so as to verify the correctness of the polarity and turns ratio of the main transformer bushing CT.

[0017] Furthermore, the first automatic take-up coil has a built-in 50-meter cable, and the second automatic take-up coil has a built-in 25-meter cable.

[0018] Furthermore, the monitoring host determines the phase sequence of the 380V maintenance power supply as follows:

[0019] Extract the voltage signal of the 380V maintenance power supply from the first operating status data;

[0020] Obtain the phase relationship of the voltage signal to determine whether the 380V maintenance power supply is a positive sequence power supply.

[0021] Furthermore, it also includes wireless receivers and wireless transmitters;

[0022] The wireless transmitter is communicatively connected to the second power quality monitoring module and is used to transmit the second operating status data collected by the second power quality monitoring module.

[0023] The wireless receiver is electrically connected to the monitoring host and wirelessly communicates with the wireless transmitter to receive the second operating status data transmitted by the wireless transmitter.

[0024] The monitoring host receives the second operating status data through a wireless receiver to establish a wireless communication connection with the second power quality monitoring module.

[0025] Furthermore, before determining the transformer's health status based on the second operating status data, the monitoring host also extracts comparative features from the second operating status data. These comparative features include at least:

[0026] Actual voltage transformation ratio, current transformation ratio, power loss, power factor difference, frequency difference, voltage THD difference, current THD difference, and harmonic amplitude ratio.

[0027] Furthermore, the monitoring host is also used for data cleaning of the comparison features, including:

[0028] The 3σ criterion was used to remove extreme outliers from the comparative features;

[0029] The missing data in the comparative features were filled by adjacent time-time interpolation and load rate correction.

[0030] Furthermore, the monitoring host is also used to perform standardized calculations on the comparative features after cleaning, using the following formula:

[0031]

[0032] In the formula, Let j be the standardized value of the j-th contrastive feature of the i-th sample. For the j-th contrast feature of the i-th sample, The j-th comparative feature is based on the mean of historical normal data of the transformer. The j-th comparative feature is the standard deviation based on the historical normal data of the transformer.

[0033] Furthermore, when the monitoring host determines the health status of the transformer based on the standardized comparative features, it also includes a principal component analysis step:

[0034] A feature matrix is ​​formed based on the standardized contrast features, and the covariance matrix of the feature matrix is ​​calculated.

[0035] Find the eigenvalues ​​and eigenvectors of the covariance matrix;

[0036] Principal components are selected based on the principle that the cumulative variance contribution rate is greater than a set threshold to achieve principal component analysis. The cumulative variance contribution rate is the ratio of the sum of the first n eigenvalues ​​to the sum of all eigenvalues, where n is the number of principal components after selection.

[0037] Furthermore, the number of principal components after screening is 3, including:

[0038] The first principal component is used to characterize energy conversion characteristics. In the unit eigenvector of the first principal component, the weight ratios of actual voltage ratio, current ratio, and power loss all exceed the first set value, which is used to reflect the state of transformer windings and insulation.

[0039] The second principal component is used to characterize the system stability. In the unit eigenvector of the second principal component, the weight ratios of frequency difference, voltage THD difference, and harmonic amplitude ratio all exceed the second set value, which is used to reflect the frequency fluctuation and harmonic interference of the transformer operation.

[0040] The third principal component is used to characterize current quality characteristics. In the unit eigenvector of the third principal component, the weight ratios of current THD difference and power factor difference both exceed the third set value, which is used to reflect the characteristics of transformer core and grounding fault status.

[0041] Furthermore, when the monitoring host determines the transformer's health status based on three principal components to verify the correctness of the main transformer bushing CT polarity and turns ratio, the determination process includes:

[0042] Preset the normal threshold ranges for the three principal components;

[0043] Extract winding insulation correlation parameters from the first principal component, extract system interference correlation parameters from the second principal component, and extract core and grounding correlation parameters from the third principal component.

[0044] If the winding insulation associated parameters, system interference associated parameters, and core and grounding associated parameters are all within their respective normal threshold ranges, then the transformer bushing CT is determined to meet the design standards and have the correct polarity. If any associated parameter exceeds the corresponding preset threshold range, then based on the specific state represented by the principal component to which the parameter belongs, the influencing factors of polarity deviation or abnormal ratio are located, and the corresponding polarity and ratio abnormality judgment results are output.

[0045] In summary, this invention provides a 380V current boosting device for a main transformer bushing CT, comprising a three-phase four-wire socket, a first automatic rewinding coil, a low-voltage circuit breaker, a second automatic rewinding coil, a first power quality monitoring module, a second power quality monitoring module, and a monitoring host. The three-phase four-wire socket is used to connect to a 380V maintenance power supply. One end of the first automatic rewinding coil is connected to the three-phase four-wire socket for rewinding the built-in cable. One end of the low-voltage circuit breaker is connected to the other end of the first automatic rewinding coil for controlling the on / off state of the primary circuit. One end of the second automatic rewinding coil is connected to the other end of the low-voltage circuit breaker, and the other end of the second automatic rewinding coil is connected to the primary side circuit of the transformer for rewinding the built-in cable, thereby achieving the connection between the primary circuit and the primary side circuit of the transformer. The first power quality monitoring module is connected to the primary circuit for monitoring the operation of the primary side circuit of the transformer. Status data; the second power quality monitoring module is connected to the secondary circuit of the transformer to monitor the operating status data of the secondary circuit; the monitoring host is electrically connected to the first automatic take-up coil, the low-voltage circuit breaker, the second automatic take-up coil, and the first power quality monitoring module, and is wirelessly connected to the second power quality monitoring module; the monitoring host is used to control the cable take-up and release of the first and second automatic take-up coils, control the on / off of the low-voltage circuit breaker, collect the first operating status data of the first power quality monitoring module and receive the second operating status data of the second power quality monitoring module, determine the phase sequence of the 380V maintenance power supply based on the first operating status data, and determine the health status of the transformer based on the second operating status data to verify the correctness of the main transformer bushing CT polarity and turns ratio. This invention collects multi-dimensional operating status data of the primary and secondary sides of the transformer through the first and second power quality monitoring modules, and performs standardized analysis by the monitoring host to verify the main transformer bushing CT polarity and turns ratio, avoiding external interference from single-dimensional manual observation, comprehensively reflecting the potential status of the CT, and significantly improving the verification accuracy and reliability of the test conclusions. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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.

[0047] Figure 1 This is a block diagram of a 380V current boosting device for a main transformer bushing CT, provided as an embodiment of the present invention. Detailed Implementation

[0048] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only 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 are within the scope of protection of this invention.

[0049] Please see Figure 1 This embodiment provides a 380V current boosting device for a main transformer bushing CT, comprising:

[0050] Three-phase four-wire socket, first automatic take-up and release coil, low-voltage circuit breaker, second automatic take-up and release coil, first power quality monitoring module, second power quality monitoring module and monitoring host;

[0051] A three-phase four-wire socket is used to connect a 380V maintenance power supply.

[0052] One end of the first automatic take-up and release coil is connected to a three-phase four-wire socket for taking up and releasing the built-in cable;

[0053] One end of the low-voltage circuit breaker is connected to the other end of the first automatic take-up coil to control the on / off of the primary circuit;

[0054] One end of the second automatic take-up coil is connected to the other end of the low-voltage circuit breaker, and the other end of the second automatic take-up coil is connected to the primary side circuit of the transformer for taking up and releasing the built-in cable to realize the connection between the primary line and the primary side circuit of the transformer.

[0055] The first power quality monitoring module is connected to the primary circuit and is used to monitor the operating status data of the primary circuit of the transformer.

[0056] The second power quality monitoring module is connected to the secondary circuit of the transformer and is used to monitor the operating status data of the secondary circuit of the transformer.

[0057] The monitoring host is electrically connected to the first automatic take-up coil, the low-voltage circuit breaker, the second automatic take-up coil, and the first power quality monitoring module, and is wirelessly connected to the second power quality monitoring module.

[0058] The monitoring host is used to control the cable winding and unwinding of the first and second automatic winding and unwinding coils, control the on / off state of the low-voltage circuit breaker, collect the first operating status data of the first power quality monitoring module and receive the second operating status data of the second power quality monitoring module, determine the phase sequence of the 380V maintenance power supply based on the first operating status data, and determine the health status of the transformer based on the second operating status data, so as to verify the correctness of the polarity and turns ratio of the main transformer bushing CT.

[0059] It should be noted that the three-phase four-wire socket is an interface component used to connect to the 380V maintenance power supply on site, providing the device with working power input; the first and second automatic retractable coils are connection components with built-in cables that can realize automatic cable retraction and extension, used to build the circuit between the device and the power supply and the primary side circuit of the transformer; the low-voltage circuit breaker is a switching component that controls the opening and closing of the primary circuit, ensuring circuit safety during the test process; the first and second power quality monitoring modules are monitoring components that are respectively connected to the primary circuit and the secondary side circuit of the transformer, used to collect operating status data such as voltage and current of the corresponding circuit; the monitoring host is the core control and data processing component of the device, responsible for managing the actions of each component, receiving and analyzing monitoring data, and completing core judgment functions. The monitoring host is electrically connected to the first automatic retractable coil (via serial port 1), the low-voltage circuit breaker (via serial port 2), the second automatic retractable coil (via serial port 4), and the first power quality monitoring module (via serial port 3). The primary circuit is a power supply circuit formed by a three-phase four-wire socket, a first automatic winding coil, a low-voltage circuit breaker, and a second automatic winding coil connected in series, used to provide test current to the primary side of the transformer; the operating status data are various electrical parameter data reflecting the operating status of the circuit collected by the power quality monitoring module.

[0060] The current booster device provided in this embodiment works by constructing a complete test circuit through an integrated device, and verifying the polarity and turns ratio of the main transformer bushing CT through data processing and analysis. First, a 380V maintenance power supply is connected through a three-phase four-wire socket. Using the cable winding and unwinding functions of the first and second automatic winding and unwinding coils, a primary circuit connecting the power supply and the primary side circuit of the transformer is established. A low-voltage circuit breaker is used to control the on / off state of this circuit to ensure controllable start and stop of the test. Second, the first power quality monitoring module monitors the operating status data of the primary circuit in real time, providing a basis for power phase sequence determination. The second power quality monitoring module simultaneously collects the operating status data of the transformer secondary side circuit and captures the output response of the CT. Finally, the monitoring host receives the two types of monitoring data through electrical connection or wireless communication. First, the phase sequence of the 380V maintenance power supply is determined based on the primary side data. Then, the secondary side data is analyzed and processed to determine the health status of the transformer. Finally, the polarity and turns ratio of the main transformer bushing CT are verified by reverse verification through the health status analysis results.

[0061] In one embodiment of the present invention, the first automatic take-up coil has a built-in 50-meter cable, and the second automatic take-up coil has a built-in 25-meter cable.

[0062] In this embodiment, the specific cable length parameters of the two types of automatic retractable coils not only meet the wiring requirements of different distances between the main transformer body and the maintenance power supply box and the primary circuit of the transformer, but also avoid the problem of inconvenience in storing and transporting traditional long cables through the automatic retractable function, further improving the adaptability and ease of operation of the device in field testing.

[0063] In one embodiment of the present invention, the monitoring host determines the phase sequence of the 380V maintenance power supply as follows:

[0064] Extract the voltage signal of the 380V maintenance power supply from the first operating status data;

[0065] Obtain the phase relationship of the voltage signal to determine whether the 380V maintenance power supply is a positive sequence power supply.

[0066] In this embodiment, the monitoring host determines the phase sequence by utilizing the phase characteristics of a positive-sequence power supply (phases A, B, and C lag by 120° sequentially). By analyzing the phase difference of the voltage signal, it identifies whether the power supply phase sequence meets the test requirements. This method transforms phase sequence determination into a standardized signal extraction and analysis process, which can accurately identify whether the power supply under maintenance is a positive-sequence power supply. It effectively avoids the shortcomings of traditional multimeters that cannot detect phase sequence errors, ensuring the accuracy of the test phase identification from the source and laying a reliable foundation for subsequent polarity and turns ratio verification.

[0067] In one embodiment of the present invention, a wireless receiver and a wireless transmitter are also included;

[0068] The wireless transmitter is communicatively connected to the second power quality monitoring module and is used to transmit the second operating status data collected by the second power quality monitoring module.

[0069] The wireless receiver is electrically connected to the monitoring host (via serial port 5) and wirelessly communicates with the wireless transmitter to receive the second operating status data transmitted by the wireless transmitter.

[0070] The monitoring host receives the second operating status data through a wireless receiver to establish a wireless communication connection with the second power quality monitoring module.

[0071] In this embodiment, a data transmission link is established by adding a wireless transmitter and a wireless receiver. The wireless transmitter communicates with the second power quality monitoring module to collect secondary-side operating status data, and then transmits the data to the wireless receiver connected to the monitoring host via wireless signal, forming a communication channel without physical wiring. This design solves the problem of inconvenient secondary-side data transmission when the main transformer and the monitoring host are far apart. It eliminates the need for additional connecting cables, maintaining flexibility in device layout while achieving real-time synchronization between secondary-side data and the monitoring host, ensuring continuous data acquisition in various scenarios.

[0072] In one embodiment of the present invention, before the monitoring host determines the health status of the transformer based on the second operating status data, it is further configured to extract comparison features from the second operating status data, the comparison features including at least:

[0073] Actual voltage ratio K U Current ratio K IPower loss ΔP, power factor difference Δcosφ, frequency difference Δf, voltage THD difference ΔTHD U , Current THD difference ΔTHD I Harmonic amplitude ratio K H .

[0074] In this embodiment, the monitoring host extracts eight comparative features from the second operating state data, including the actual voltage ratio and current ratio. This can cover core dimensions affecting CT performance, such as voltage conversion, current transmission, power loss, and harmonic interference, thus breaking away from the traditional single observation logic that relies solely on current magnitude and angle. This design provides comprehensive and multi-dimensional data support for transformer health status analysis, and can capture potential state information such as CT winding insulation and core characteristics. This lays the data foundation for subsequent accurate verification of polarity and ratio, and makes up for the shortcomings of insufficient dimensions in traditional test data.

[0075] In one embodiment of the present invention, the monitoring host is further configured to perform data cleaning on the comparison features, including:

[0076] The 3σ criterion was used to remove extreme outliers from the comparative features;

[0077] The missing data in the comparative features were filled by adjacent time-time interpolation and load rate correction.

[0078] In this embodiment, the monitoring host uses the 3σ criterion to remove extreme outliers, adjacent time-time interpolation, and load rate correction to clean and compare features. Specifically, the 3σ criterion (data falling outside the mean ± 3 standard deviations is considered outlier) filters out interfering data. Missing data is accurately filled in using the correlation between adjacent time-time data and the load rate (for example, if ΔP is missing at a certain time, it is corrected by combining the average ΔP from the previous 10ms and the next 10ms with the current load rate of 0.8, avoiding linear interpolation errors). This ensures data integrity and accuracy. Finally, the cleaned data is integrated to form an 8-dimensional feature matrix X. m×8 (m is the number of samples, such as 1000 sets of running data); This design can eliminate abnormal interference and missing gaps in the monitoring data, avoid the deviation of subsequent analysis results caused by poor data, provide high-quality data input for standardized calculation and principal component analysis, and improve the reliability of the final judgment results.

[0079] In one embodiment of the present invention, the monitoring host is further configured to perform standardized calculations on the cleaned comparison features, the calculation formula being:

[0080]

[0081] In the formula, Let j be the standardized value of the j-th contrastive feature of the i-th sample. For the j-th contrast feature of the i-th sample, The j-th comparison feature is based on the mean of the transformer's historical normal data (e.g., the mean Δf during normal operation is 0.02Hz). The j-th comparative feature is based on the standard deviation of the transformer's historical normal data (e.g., the standard deviation of Δf is 0.015Hz).

[0082] In this embodiment, the average of historical normal data of the transformer is used. with standard deviation This method unifies the comparative features of different dimensions and numerical ranges into standardized data with a mean of 0 and a variance of 1, thus balancing the weights of each feature. Standardization eliminates analytical biases caused by inherent numerical differences in features (such as large differences in the numerical ranges of voltage ratio and harmonic amplitude ratio), ensuring the objectivity and accuracy of the analysis process.

[0083] In one embodiment of the present invention, when the monitoring host determines the health status of the transformer based on the standardized comparative features, it further includes a principal component analysis step:

[0084] S11: Form a feature matrix based on the standardized contrast features, and calculate the covariance matrix of the feature matrix.

[0085] For example, for the standardized feature matrix Z m×8 The 8×8 covariance matrix is ​​calculated as follows:

[0086]

[0087] In the formula, The element in the j-th row and k-th column of the 8×8 covariance matrix represents the covariance between the j-th standardized feature and the k-th standardized feature, reflecting the degree of linear correlation between these two features. Indicates the number of samples; This represents the standardized value of the j-th comparative feature in the i-th sample. Let represent the mean of all samples after standardization of the j-th contrast feature; This represents the standardized value of the k-th comparative feature in the i-th sample. This represents the mean of all samples after standardization for the k-th comparative feature. This matrix reflects the degree of linear correlation between features, such as... This indicates a strong positive correlation between power loss and power factor difference, requiring dimensionality reduction and information merging.

[0088] S12: Solve for the eigenvalues ​​and eigenvectors of the covariance matrix.

[0089] It should be noted that the eigenvalues ​​of the covariance matrix C can be calculated using the Jacobi iteration method, such as... and corresponding unit eigenvectors Eigenvalues This represents the information contribution of the j-th principal component. For example, it is calculated for a 110kV transformer sample: , , All other eigenvalues ​​are less than 0.5.

[0090] S13: Principal components are selected based on the principle that the cumulative variance contribution rate is greater than a set threshold in order to achieve principal component analysis; the cumulative variance contribution rate is the ratio of the sum of the first n eigenvalues ​​to the sum of all eigenvalues, where n is the number of principal components after selection.

[0091] For example, the number of principal components can be determined based on the principle that the cumulative variance contribution rate is ≥85%. For the above sample, the cumulative variance contribution rate of the first three principal components is:

[0092]

[0093] To meet the information retention requirements, the 8-dimensional features are reduced to 3-dimensional principal components F1, F2 and F3.

[0094] In this embodiment, the covariance matrix can be used to reflect the degree of linear correlation between features. The contribution of principal components is characterized by eigenvalues. Core principal components are selected according to the cumulative variance contribution rate threshold, which simplifies data complexity while retaining key information. The purpose of this design is to reduce the difficulty of analyzing multi-dimensional data, improve data processing efficiency, focus on the correlation of core features, avoid redundant information interference, and provide an efficient and focused analysis path for subsequent accurate determination of transformer health status.

[0095] In one embodiment of the present invention, the number of principal components after screening is three, including:

[0096] The first principal component is used to characterize energy conversion characteristics. In the unit eigenvector of the first principal component, the weights of actual voltage ratio, current ratio, and power loss all exceed 30%, which are used to reflect the state of transformer windings and insulation.

[0097] For example, F1 = 0.32K U +0.28K I +0.35ΔP+0.15Δcosφ, with a weighting ratio exceeding 30%, indicates a transformation ratio and power loss, which are directly related to the winding and insulation conditions.

[0098] The second principal component is used to characterize system stability. In the unit eigenvector of the second principal component, the weights of frequency difference, voltage THD difference, and harmonic amplitude ratio all exceed 30%, which is used to reflect the frequency fluctuation and harmonic interference of transformer operation.

[0099] For example, F2 = 0.42Δf + 0.38ΔTHD - U + 0.20K H Defined as a system stability characteristic, reflecting frequency fluctuations and harmonic interference.

[0100] The third principal component is used to characterize current quality characteristics. In the unit eigenvector of the third principal component, the weights of current THD difference and power factor difference both exceed 30%, which are used to reflect the characteristics of transformer core and grounding fault status.

[0101] For example, F3 = 0.51ΔTHD-I + 0.49Δcosφ is defined as the current quality characteristic, corresponding to core and grounding faults.

[0102] The three principal components selected in this embodiment correspond to energy conversion characteristics, system stability, and current quality characteristics, respectively. The implementation principle is based on the core comparative features in each principal component whose weight ratio exceeds the set value. The abstract multi-dimensional data is transformed into physical indicators that can be interpreted intuitively, respectively mapping key states such as transformer winding insulation, system interference, core and grounding faults. This embodiment can achieve accurate characterization of the core state of the transformer.

[0103] In one embodiment of the present invention, when the monitoring host determines the health status of the transformer based on three principal components to verify the correctness of the main transformer bushing CT polarity and turns ratio, the determination process includes:

[0104] S21: Preset the normal threshold range for the three principal components;

[0105] S22: Extract winding insulation correlation parameters from the first principal component, extract system interference correlation parameters from the second principal component, and extract core and grounding correlation parameters from the third principal component;

[0106] S23: If the winding insulation associated parameters, system interference associated parameters, and core and grounding associated parameters are all within their respective normal threshold ranges, then the transformer bushing CT is determined to meet the design standard and have the correct polarity; if any associated parameter exceeds the corresponding preset threshold range, then the factors affecting the polarity deviation or abnormal ratio are located according to the specific state represented by the principal component to which the parameter belongs, and the corresponding polarity and ratio abnormality judgment results are output.

[0107] In this embodiment, the monitoring host verifies the CT polarity and ratio by setting a preset normal threshold range, extracting three types of related parameters, and finally comparing the results through threshold comparison. The principle behind this is to set the threshold of principal component parameters based on historical normal data, extract the corresponding key parameters from the three principal components, and determine the working status of the CT by whether the parameters are within the threshold, thus forming a standardized judgment logic. The purpose of this design is to build a dual-function system for accurate verification and anomaly localization. It can accurately determine the correctness of the CT ratio and polarity, and quickly locate the root cause of anomalies (such as winding insulation deterioration, harmonic interference, etc.), significantly improving the reliability and practicality of the test conclusions, and completely solving the defects of insufficient accuracy and inability to locate the cause of anomalies in traditional tests.

[0108] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0109] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0110] In the embodiments disclosed in this application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling or direct coupling or communication connection may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0111] 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A 380V current boosting device for a main transformer bushing CT, characterized in that, include: Three-phase four-wire socket, first automatic take-up and release coil, low-voltage circuit breaker, second automatic take-up and release coil, first power quality monitoring module, second power quality monitoring module and monitoring host; The three-phase four-wire socket is used to connect to a 380V maintenance power supply. One end of the first automatic retractable coil is connected to the three-phase four-wire socket for retracting and extending the built-in cable; One end of the low-voltage circuit breaker is connected to the other end of the first automatic take-up and release coil, and is used to control the on / off of the primary line; One end of the second automatic take-up coil is connected to the other end of the low-voltage circuit breaker, and the other end of the second automatic take-up coil is connected to the primary side circuit of the transformer for taking up and releasing the built-in cable, so as to realize the connection between the primary line and the primary side circuit of the transformer. The first power quality monitoring module is connected to the primary circuit and is used to monitor the operating status data of the primary circuit of the transformer; The second power quality monitoring module is connected to the secondary circuit of the transformer and is used to monitor the operating status data of the secondary circuit of the transformer. The monitoring host is electrically connected to the first automatic take-up coil, the low-voltage circuit breaker, the second automatic take-up coil, and the first power quality monitoring module, respectively, and is wirelessly connected to the second power quality monitoring module. The monitoring host is used to control the cable winding and unwinding of the first automatic winding and unwinding coil and the second automatic winding and unwinding coil, control the on and off of the low-voltage circuit breaker, collect the first operating status data of the first power quality monitoring module and receive the second operating status data of the second power quality monitoring module, determine the phase sequence of the 380V maintenance power supply based on the first operating status data, and determine the health status of the transformer based on the second operating status data, so as to verify the correctness of the polarity and turns ratio of the main transformer bushing CT.

2. The main transformer bushing CT 380V current boosting device according to claim 1, characterized in that, The first automatic retractable coil has a built-in 50-meter cable, and the second automatic retractable coil has a built-in 25-meter cable.

3. The main transformer bushing CT 380V current boosting device according to claim 1, characterized in that, The monitoring host determines the phase sequence of the 380V maintenance power supply as follows: Extract the voltage signal of the 380V maintenance power supply from the first operating status data; The phase relationship of the voltage signal is obtained to determine whether the 380V maintenance power supply is a positive sequence power supply.

4. The main transformer bushing CT 380V current boosting device according to claim 1, characterized in that, It also includes wireless receivers and wireless transmitters; The wireless transmitter is communicatively connected to the second power quality monitoring module and is used to transmit the second operating status data collected by the second power quality monitoring module. The wireless receiver is electrically connected to the monitoring host and wirelessly communicates with the wireless transmitter to receive the second operating status data transmitted by the wireless transmitter. The monitoring host receives the second operating status data through the wireless receiver to achieve a wireless communication connection with the second power quality monitoring module.

5. The main transformer bushing CT 380V current boosting device according to claim 1, characterized in that, Before determining the transformer's health status based on the second operating status data, the monitoring host is further configured to extract comparative features from the second operating status data, the comparative features including at least: Actual voltage transformation ratio, current transformation ratio, power loss, power factor difference, frequency difference, voltage THD difference, current THD difference, and harmonic amplitude ratio.

6. The main transformer bushing CT 380V current boosting device according to claim 5, characterized in that, The monitoring host is also used to perform data cleaning on the comparison features, including: Extreme outliers in the comparison features are removed using the 3σ criterion. The missing data in the comparative features are filled by adjacent time-time interpolation and load rate correction.

7. The main transformer bushing CT 380V current boosting device according to claim 6, characterized in that, The monitoring host is also used to standardize the comparison features after cleaning, and the calculation formula is: In the formula, Let j be the standardized value of the j-th contrastive feature of the i-th sample. For the j-th contrast feature of the i-th sample, The j-th comparative feature is based on the mean of historical normal data of the transformer. The j-th comparative feature is the standard deviation based on the historical normal data of the transformer.

8. The CT380V current booster device for main transformer bushings according to claim 7, characterized in that, When the monitoring host determines the health status of the transformer based on the standardized comparative features, it also includes a principal component analysis step: A feature matrix is ​​formed based on the standardized contrast features, and the covariance matrix of the feature matrix is ​​calculated. Solve for the eigenvalues ​​and eigenvectors of the covariance matrix; Principal components are selected based on the principle that the cumulative variance contribution rate is greater than a set threshold to achieve principal component analysis; the cumulative variance contribution rate is the ratio of the sum of the first n eigenvalues ​​to the sum of all eigenvalues, where n is the number of principal components after selection.

9. The main transformer bushing CT 380V current boosting device according to claim 8, characterized in that, The number of principal components after screening is 3, including: The first principal component is used to characterize energy conversion characteristics. In the unit eigenvector of the first principal component, the weight ratios of actual voltage ratio, current ratio, and power loss all exceed the first set value, which is used to reflect the state of transformer windings and insulation. The second principal component is used to characterize the system stability. In the unit eigenvector of the second principal component, the weight ratios of frequency difference, voltage THD difference, and harmonic amplitude ratio all exceed the second set value, which is used to reflect the frequency fluctuation and harmonic interference of the transformer operation. The third principal component is used to characterize current quality characteristics. In the unit eigenvector of the third principal component, the weight ratios of current THD difference and power factor difference both exceed the third set value, which is used to reflect the characteristics of transformer core and grounding fault status.

10. The main transformer bushing CT 380V current boosting device according to claim 9, characterized in that, When the monitoring host determines the transformer health status based on three principal components to verify the correctness of the main transformer bushing CT polarity and turns ratio, the determination process includes: Preset the normal threshold ranges for the three principal components; Extract winding insulation correlation parameters from the first principal component, extract system interference correlation parameters from the second principal component, and extract core and grounding correlation parameters from the third principal component; If the winding insulation correlation parameter, system interference correlation parameter, and core and grounding correlation parameter are all within their respective normal threshold ranges, then the transformer bushing CT is determined to meet the design standard and have the correct polarity; if any correlation parameter exceeds the corresponding preset threshold range, then the influencing factors of polarity deviation or ratio abnormality are located according to the specific state represented by the principal component to which the parameter belongs, and the corresponding polarity and ratio abnormality judgment results are output.

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