Method and device for judging single or double position switching of on-load tap changer of transformer

Abstract

Embodiments of the present application provide a single-to-double and double-to-single position switching judgment method and device for a transformer on-load tap changer, and relate to the technical field of power equipment state monitoring. The judgment method comprises: S1: recording vibration signals in each switching process during on-load tap changer switching operation, to obtain multiple sets of monitoring data under single-to-double and double-to-single switching modes; S2: preprocessing the vibration signals, extracting time intervals between the vibration signals under the two switching modes, and calculating the mean and variance of the time intervals; S3: selecting the time interval with the largest difference as a characteristic value; and S4: setting a time criterion, comparing the characteristic value with the time criterion, and automatically identifying the single-to-double and double-to-single switching modes. The method and device can realize single-to-double and double-to-single position switching identification for the on-load tap changer, provide important support for transformer on-load tap changer state evaluation, and have good practical value.

Description

Technical Field

[0001] This invention relates to the field of power equipment condition monitoring technology, and more specifically, to a method and device for judging the single and double tap switching of an on-load tap changer in a transformer. Background Technology

[0002] On-load tap changers, as one of the core components of transformers / converter transformers, play a crucial role in stabilizing grid load center voltage, regulating reactive power flow, and increasing the flexibility of power system dispatch. Statistics show that transformer / converter transformer faults and defects caused by on-load tap changers account for a significant proportion and are prone to triggering chain reactions, posing a considerable threat to the safe operation of the power grid. Therefore, conducting condition monitoring and assessment of on-load tap changers is of great importance.

[0003] The switching principle of on-load tap changers involves switching the transformer from one tap to another without interrupting transformer power, thereby changing the effective number of turns in the winding to achieve voltage regulation. The switching process can be divided into two types: ① "odd-numbered tap to even-numbered tap" (single to double) and ② "even-numbered tap to odd-numbered tap" (double to single). However, most existing research does not strictly distinguish between these two types. Field testing has revealed differences between the two switching processes of on-load tap changers, with significant differences in the timing characteristics of some processes. Clearly, failing to differentiate between these two switching processes will affect the effectiveness of on-load tap changer condition assessment. Existing condition assessment systems do not incorporate on-load tap changer tap adjustment information, making it impossible to determine whether it is a single to double or double to single switch. Summary of the Invention

[0004] The present invention aims to provide a method and apparatus for judging the single-to-double tap changer switching of a transformer on-load tap changer, which can automatically identify whether the switching is from single to double or from double to single, providing important support for the status assessment of the on-load tap changer.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a method for determining the single / double tap switching of an on-load tap changer in a transformer, the method comprising:

[0007] S1: During the on-load tap changer switching operation, record the vibration signal of each switching process to obtain multiple sets of monitoring data under the two switching modes of single to double and double to single.

[0008] S2: Preprocess the vibration signal, extract the time interval between the vibration signals under the two switching modes, and calculate the mean and variance of the time interval;

[0009] S3: Select the time interval with the largest difference as the feature value;

[0010] S4: Set time criteria, compare feature values ​​with time criteria, and automatically identify two switching modes: single to double and double to single.

[0011] In an optional implementation, S1 includes:

[0012] An accelerometer is placed on the top cover of the on-load tap changer's oil tank to collect vibration signals during the switching process.

[0013] In an optional implementation, S2 includes:

[0014] Wavelet analysis was used to denoise the vibration signal.

[0015] In an optional implementation, the noise reduction processing of the vibration signal using wavelet analysis includes:

[0016] Using bior3.3 as the wavelet basis, the vibration signal was decomposed into 8 layers and reconstructed to obtain the denoised vibration signal.

[0017] In an optional implementation, S2 includes:

[0018] Extract the time intervals between vibration signals under single-to-dual switching mode, and calculate the mean and variance of each time interval;

[0019] Extract the time intervals between vibration signals under dual-to-single switching mode, and calculate the mean and variance of each time interval.

[0020] In an optional implementation, S3 includes:

[0021] Calculate the difference between the time interval between vibration signals under single-to-dual switching mode and the time interval between vibration signals under dual-to-single switching mode;

[0022] Select the time interval corresponding to the largest difference as the feature value.

[0023] In an optional implementation, S4 includes:

[0024] Set a threshold;

[0025] Compare the relationship between the time interval and the threshold;

[0026] If the time interval is not less than the threshold, it is considered that the on-load tap changer is performing a double-to-single switchover; if the time interval is less than the threshold, it is considered that the on-load tap changer is performing a single-to-double switchover.

[0027] Secondly, the present invention also provides a transformer on-load tap changer single / double tap switching judgment device, the device comprising:

[0028] The acquisition module is used to record the vibration signal of each switching process during the on-load tap changer switching operation, and obtain multiple sets of monitoring data under the two switching modes of single to double and double to single.

[0029] The processing module is used to preprocess the vibration signal, extract the time interval between the vibration signals under the two switching modes, and calculate the mean and variance of the time interval; it is also used to filter the time interval with the largest difference as the feature value; it is also used to set the time criterion, compare the feature value with the time criterion, and automatically identify the two switching modes of single to double and double to single.

[0030] The beneficial effects of the transformer on-load tap changer single / double tap switching judgment method and device provided in this embodiment of the invention include:

[0031] First, during on-load tap changer switching operations, vibration signals are recorded for each switching process, obtaining multiple sets of monitoring data for both single-to-double and double-to-single switching modes. Then, the vibration signals are preprocessed, and the time intervals between the vibration signals under both switching modes are extracted, with the mean and variance of the time intervals calculated. Next, the time intervals with the largest differences are selected as feature values. Finally, a time criterion is set, and the feature values ​​are compared with the time criterion to automatically identify the single-to-double and double-to-single switching modes. This method can realize the identification of single-to-double and double-to-single tap changer switching modes, providing important support for the condition assessment of transformer on-load tap changers and possessing significant practical value. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A flowchart of a method for determining the single / double tap position switching of an on-load tap changer for a transformer, provided in an embodiment of the present invention;

[0034] Figure 2 The vibration signal during single-to-double shifting operation of the VR type on-load tap changer;

[0035] Figure 3 The vibration signal during the double-to-single shift operation of the VR type on-load tap changer;

[0036] Figure 4 The diagram illustrates the time intervals with the greatest differences. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0040] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0041] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0042] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0043] Please refer to Figure 1 This embodiment provides a method for determining the single / double tap switching of an on-load tap changer in a transformer (hereinafter referred to as the "determination method"). The determination method includes the following steps:

[0044] S1: During on-load tap changer switching operations, record the vibration signal of each switching process to obtain multiple sets of monitoring data under both single-to-double and double-to-single switching modes.

[0045] In this embodiment, taking a VR-type on-load tap changer as an example, an acceleration sensor is arranged on the top cover of the on-load tap changer's oil tank to collect vibration signals during the switching process, ultimately obtaining 100 sets of vibration signals for the single-to-double switching process (e.g., Figure 2 (as shown) and vibration signals from 100 sets of dual-to-single switching processes (such as...) Figure 3 (As shown). The entire acquisition process lasted 250ms. It can be seen that there are 7 vibration signals with large amplitude in each of the two vibration signals, and the time intervals between the vibration signals are significantly different.

[0046] S2: Preprocess the vibration signal, extract the time interval between the vibration signals under the two switching modes, and calculate the mean and variance of the time interval.

[0047] In this embodiment, wavelet analysis is used to denoise the vibration signal. Bior3.3 is used as the wavelet basis, and the vibration signal is decomposed into 8 layers and reconstructed to obtain the denoised vibration signal.

[0048] Please refer to Figure 2 The time intervals between vibration signals under single-to-dual switching mode were extracted. Specifically: the mean time interval t1 between vibration signals ① and ② is 33.3 ms, with a variance of 0.2 ms. The mean time interval t2 between vibration signals ② and ③ is 8.3 ms, with a variance of 0.2 ms. The mean time interval t3 between vibration signals ③ and ④ is 8.8 ms, with a variance of 0.2 ms. The mean time interval t4 between vibration signals ④ and ⑤ is 38.7 ms, with a variance of 0.2 ms. The mean time interval t5 between vibration signals ⑤ and ⑥ is 9.2 ms, with a variance of 0.1 ms. The mean time interval t6 between vibration signals ⑥ and ⑦ is 11.9 ms, with a variance of 0.2 ms. Since the variances of all the above data do not exceed 0.2 ms, the data consistency is good.

[0049] Please refer to Figure 3 The time intervals between vibration signals in the dual-to-single switching mode were extracted. Specifically: the mean time interval t1 between vibration signals ① and ② is 37.5 ms, with a variance of 0.2 ms. The mean time interval t2 between vibration signals ② and ③ is 9.9 ms, with a variance of 0.2 ms. The mean time interval t3 between vibration signals ③ and ④ is 9.5 ms, with a variance of 0.2 ms. The mean time interval t4 between vibration signals ④ and ⑤ is 39.2 ms, with a variance of 0.2 ms. The mean time interval t5 between vibration signals ⑤ and ⑥ is 9.4 ms, with a variance of 0.1 ms. The mean time interval t6 between vibration signals ⑥ and ⑦ is 15.7 ms, with a variance of 0.2 ms. Since the variances of all the above data do not exceed 0.2 ms, the data consistency is good.

[0050] S3: Select the time interval with the largest difference as the feature value.

[0051] In this embodiment, firstly, the difference between the time interval between vibration signals under the single-to-dual switching mode and the time interval between vibration signals under the corresponding dual-to-single switching mode is calculated; then, the time interval corresponding to the largest difference is selected as the feature value.

[0052] Specifically, the difference in t1 is the most significant, with 33.3ms for the change from odd to even and 37.5ms for the change from even to odd, a difference of 4.2ms; the difference in t6 is also relatively large, with 11.9ms for the change from odd to even and 15.7ms for the change from even to odd, a difference of 3.8ms; the difference in t2 is relatively small, with 8.3ms for the change from odd to even and 9.9ms for the change from even to odd, a difference of 1.6ms; the differences in the remaining time intervals are all within 1ms. In this embodiment, t1 and t6 are selected as feature values, such as... Figure 4 As shown.

[0053] S4: Set time criteria, compare feature values ​​with time criteria, and automatically identify two switching modes: single to double and double to single.

[0054] In this embodiment, firstly, a threshold is set; then, the relationship between the time interval and the threshold is compared. If the time interval is not less than the threshold, it is considered that the on-load tap changer is performing a double-to-single switchover; if the time interval is less than the threshold, it is considered that the on-load tap changer is performing a single-to-double switchover.

[0055] Specifically, the threshold for t1 is set to 35.4ms, and the threshold for t6 is set to 13.8ms. If t1 ≥ 35.4ms and t6 ≥ 13.8ms, the on-load tap changer is considered to be performing a double-to-single switchover; if t1 < 35.4ms and t6 < 13.8ms, the on-load tap changer is considered to be performing a single-to-double switchover.

[0056] This invention also provides a transformer on-load tap changer single / double tap switching judgment device, the device including a data acquisition module and a processing module connected to each other.

[0057] Specifically, the acquisition module includes an acceleration sensor. The acquisition module is used to record the vibration signal of each switching process during the on-load tap changer switching operation, and obtain multiple sets of monitoring data under the two switching modes of single to double and double to single; that is, to execute S1 in the above judgment method.

[0058] The processing module is used to preprocess the vibration signal, extract the time interval between the vibration signals under the two switching modes, and calculate the mean and variance of the time interval; it is also used to filter the time interval with the largest difference as the feature value; it is also used to set the time criterion, compare the feature value with the time criterion, and automatically identify the two switching modes of single to double and double to single; that is, to execute S2 to S4 in the above judgment method.

[0059] The beneficial effects of the transformer on-load tap changer single / double tap switching judgment method and device provided in this embodiment of the invention include:

[0060] First, during on-load tap changer switching operations, vibration signals are recorded for each switching process, obtaining multiple sets of monitoring data for both single-to-double and double-to-single switching modes. Then, the vibration signals are preprocessed, and the time intervals between the vibration signals under both switching modes are extracted, with the mean and variance of the time intervals calculated. Next, the time intervals with the largest differences are selected as feature values. Finally, a time criterion is set, and the feature values ​​are compared with the time criterion to automatically identify the single-to-double and double-to-single switching modes. This method can realize the identification of single-to-double and double-to-single tap changer switching modes, providing important support for the condition assessment of transformer on-load tap changers and possessing significant practical value.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for determining the single / double tap switching of an on-load tap changer in a transformer, characterized in that, The determination method includes: S1: During the on-load tap changer switching operation, record the vibration signal of each switching process to obtain multiple sets of monitoring data under the two switching modes of single to double and double to single. S2: Preprocess the vibration signal and extract the time interval between the vibration signals under the two switching modes, and calculate the mean and variance of the time interval; extract the time interval between the vibration signals under the single-to-dual switching mode; wherein: the mean of the time interval t1 between vibration signals ① and ② is 33.3ms, and the variance is 0.2ms; the mean of the time interval t2 between vibration signals ② and ③ is 8.3ms, and the variance is 0.2ms; the mean of the time interval t3 between vibration signals ③ and ④ is 8.8ms, and the variance is 0.2ms; the mean of the time interval t4 between vibration signals ④ and ⑤ is 38.7ms, and the variance is 0.2ms; the mean of the time interval t5 between vibration signals ⑤ and ⑥ is 9.2ms, and the variance is 0.1ms; the mean of the time interval t5 between vibration signals ⑥ and ⑦ is... The mean time interval t6 is 11.9 ms, and the variance is 0.2 ms. The time intervals between vibration signals under the dual-to-single switching mode are extracted; specifically: the mean time interval t1 between vibration signals ① and ② is 37.5 ms, and the variance is 0.2 ms; the mean time interval t2 between vibration signals ② and ③ is 9.9 ms, and the variance is 0.2 ms; the mean time interval t3 between vibration signals ③ and ④ is 9.5 ms, and the variance is 0.2 ms; the mean time interval t4 between vibration signals ④ and ⑤ is 39.2 ms, and the variance is 0.2 ms; the mean time interval t5 between vibration signals ⑤ and ⑥ is 9.4 ms, and the variance is 0.1 ms; the mean time interval t6 between vibration signals ⑥ and ⑦ is 15.7 ms, and the variance is 0.2 ms. S3: Calculate the difference between the vibration signal time interval under the single-to-dual switching mode and the vibration signal time interval under the corresponding dual-to-single switching mode, and select the time interval with the largest difference as the feature value; t1 has the most significant difference, 33.3ms for single-to-dual and 37.5ms for dual-to-single, a difference of 4.2ms; t6 also has a large difference, 11.9ms for single-to-dual and 15.7ms for dual-to-single, a difference of 3.8ms. Select t1 and t6 as feature values; S4: Set a time criterion, compare the feature value with the time criterion, and automatically identify the two switching modes: single-to-double and double-to-single. The time criterion is a set threshold. The threshold for t1 is set to 35.4ms, and the threshold for t6 is set to 13.8ms. If t1≥35.4ms and t6≥13.8ms, it is considered that the on-load tap changer is performing double-to-single switching. If t1<35.4ms and t6<13.8ms, it is considered that the on-load tap changer is performing single-to-double switching.

2. The method for determining single / double tap switching of an on-load tap changer in a transformer according to claim 1, characterized in that, S1 includes: An accelerometer is placed on the top cover of the on-load tap changer's oil tank to collect vibration signals during the switching process.

3. The method for determining single / double tap switching of an on-load tap changer in a transformer according to claim 1, characterized in that, S2 includes: Wavelet analysis was used to denoise the vibration signal.

4. The method for determining single / double tap switching of an on-load tap changer in a transformer according to claim 3, characterized in that, The noise reduction processing of the vibration signal using wavelet analysis includes: Using bior3.3 as the wavelet basis, the vibration signal was decomposed into 8 layers and reconstructed to obtain the denoised vibration signal.

5. A device for judging the single / double tap switching of an on-load tap changer for a transformer, characterized in that, The device includes: The acquisition module is used to record the vibration signal of each switching process during the on-load tap changer switching operation, and obtain multiple sets of monitoring data under the two switching modes of single to double and double to single. The processing module is used to preprocess the vibration signal, extract the time interval between vibration signals under the two switching modes, and calculate the mean and variance of the time interval; extract the time interval between vibration signals under the single-to-dual switching mode; wherein: the mean of the time interval t1 between vibration signals ① and ② is 33.3ms, and the variance is 0.2ms; the mean of the time interval t2 between vibration signals ② and ③ is 8.3ms, and the variance is 0.2ms; the mean of the time interval t3 between vibration signals ③ and ④ is 8.8ms, and the variance is 0.2ms; the mean of the time interval t4 between vibration signals ④ and ⑤ is 38.7ms, and the variance is 0.2ms; the mean of the time interval t5 between vibration signals ⑤ and ⑥ is 9.2ms, and the variance is 0.1ms; vibration signal ⑥ The mean time interval t6 between vibration signals ① and ② is 11.9 ms, and the variance is 0.2 ms. The time intervals between vibration signals under the dual-to-single switching mode are extracted; specifically: the mean time interval t1 between vibration signals ① and ② is 37.5 ms, and the variance is 0.2 ms; the mean time interval t2 between vibration signals ② and ③ is 9.9 ms, and the variance is 0.2 ms; the mean time interval t3 between vibration signals ③ and ④ is 9.5 ms, and the variance is 0.2 ms; the mean time interval t4 between vibration signals ④ and ⑤ is 39.2 ms, and the variance is 0.2 ms; the mean time interval t5 between vibration signals ⑤ and ⑥ is 9.4 ms, and the variance is 0.1 ms; the mean time interval t6 between vibration signals ⑥ and ⑦ is 15.7 ms, and the variance is 0.2 ms. It is also used to calculate the difference between the vibration signal time interval under the single-to-dual switching mode and the vibration signal time interval under the corresponding dual-to-single switching mode, and select the time interval with the largest difference as the feature value; t1 has the most significant difference, which is 33.3ms when switching from single to dual and 37.5ms when switching from dual to single, with a difference of 4.2ms; t6 also has a large difference, which is 11.9ms when switching from single to dual and 15.7ms when switching from dual to single, with a difference of 3.8ms. t1 and t6 are selected as feature values. It is also used to set time criteria, compare the feature value with the time criteria, and automatically identify the two switching modes: single-to-double and double-to-single. The time criteria are the set thresholds; the threshold for t1 is set to 35.4ms, and the threshold for t6 is set to 13.8ms. If t1≥35.4ms and t6≥13.8ms, it is considered that the on-load tap changer is performing double-to-single switching; if t1<35.4ms and t6<13.8ms, it is considered that the on-load tap changer is performing single-to-double switching.

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