CN115435893A - Method for extracting vibration signal of on-load tap-changer of transformer - Google Patents
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Abstract
本发明的实施例提供了一种变压器有载分接开关振动信号提取方法，涉及变压器有载分接开关状态监测技术领域。方法通过对OLTC油箱顶盖或变压器油箱外壳表面的振动信号进行监测，首先通过预处理，对每帧振动信号进行傅里叶变换得到信号频谱图，将频谱图划分为多个子频带并计算每帧信号的能量谱熵，通过设置能量谱熵门限和时间门限获取信号的起点和终点，实现从数秒长的振动信号中分离出毫秒级的OLTC振动信号片段。该方法能自动实现OLTC振动信号提取，便于OLTC在线监测技术的推广和使用，为OLTC机械状态评估提供基础和支撑，具有很好的实用价值。
An embodiment of the present invention provides a method for extracting a vibration signal of an on-load tap changer of a transformer, and relates to the technical field of state monitoring of an on-load tap changer of a transformer. Methods By monitoring the vibration signal on the top cover of the OLTC oil tank or the surface of the transformer oil tank shell, firstly through preprocessing, Fourier transform is performed on each frame of the vibration signal to obtain the signal spectrum, and the spectrum is divided into multiple sub-bands and calculated for each frame. The energy spectrum entropy of the signal, by setting the energy spectrum entropy threshold and time threshold to obtain the start and end of the signal, realizes the separation of millisecond-level OLTC vibration signal fragments from the several-second long vibration signal. This method can automatically realize the extraction of OLTC vibration signals, facilitate the promotion and use of OLTC online monitoring technology, and provide the basis and support for OLTC mechanical state evaluation, which has good practical value.
Description
技术领域technical field
本发明涉及变压器有载分接开关状态监测技术领域，具体而言，涉及一种变压器有载分接开关振动信号提取方法。The invention relates to the technical field of transformer on-load tap changer state monitoring, in particular to a method for extracting a vibration signal of a transformer on-load tap changer.
背景技术Background technique
变压器是电力系统的关键设备，有载分接开关(on-load tap-changer，简称：OLTC)作为变压器中唯一频繁动作的核心部件，承担着调节无功功率、稳定电网电压的重要作用，其运行可靠性对于变压器具有重要意义。统计表明，OLTC异常引起的故障约占变压器总故障的30％，OLTC故障主要包括机械故障和电气故障，其中，机械故障占比超过90％。OLTC一旦发生机械故障，轻则导致线路跳闸、损失输送功率，重则引发变压器起火烧毁，造成巨大的经济损失和不良的社会影响。因此，对OLTC机械状态进行检测和诊断具有重要意义。The transformer is the key equipment of the power system. The on-load tap-changer (OLTC for short) is the only core component in the transformer that operates frequently. It is responsible for adjusting reactive power and stabilizing the grid voltage. Operational reliability is of great importance for transformers. Statistics show that faults caused by OLTC abnormalities account for about 30% of the total transformer faults, and OLTC faults mainly include mechanical faults and electrical faults, of which mechanical faults account for more than 90%. Once a mechanical failure occurs in the OLTC, it will cause line tripping and loss of transmission power, or cause the transformer to catch fire and burn down, causing huge economic losses and adverse social impacts. Therefore, it is of great significance to detect and diagnose the mechanical state of OLTC.
目前，OLTC普遍采用停电检修的方式，但该方式费时费力且不能实现设备状态在线监测。振动法具有灵敏度高、安装方便、与变压器无直接电气连接、易于实现带电检测等优点，近年来在电力设备状态监测中应用广泛。OLTC切换时动静触头等零部件机构间的碰撞与摩擦会引起机械振动，而振动信号中包含了大量的设备状态信息，因此振动法已逐渐成为OLTC机械状态在线监测的关注热点。现有的OLTC机械状态在线监测系统普遍采用电机电流信号作触发，同步采集数秒的振动信号，而变压器OLTC切换动作引起的振动信号时长仅为毫秒级，进行OLTC机械状态诊断的前提是从数秒长的振动信号中提出OLTC振动信号片段，采用人工提取的方法费时费力，且需要专业人员来完成，不便于该项技术的推广和使用，而关于OLTC振动信号定位和提取的方法却鲜有报告。At present, OLTC generally adopts the method of power outage maintenance, but this method is time-consuming and laborious and cannot realize online monitoring of equipment status. The vibration method has the advantages of high sensitivity, convenient installation, no direct electrical connection with the transformer, and easy live detection. It has been widely used in power equipment condition monitoring in recent years. The collision and friction between the dynamic and static contacts and other parts and mechanisms during OLTC switching will cause mechanical vibration, and the vibration signal contains a large amount of equipment status information, so the vibration method has gradually become a hot spot for online monitoring of OLTC mechanical status. Existing OLTC mechanical status online monitoring systems generally use motor current signals as triggers to collect vibration signals for several seconds synchronously, while the duration of vibration signals caused by transformer OLTC switching actions is only milliseconds. It is time-consuming and laborious to extract the OLTC vibration signal segment from the vibration signal of the OLTC, and it needs professionals to complete it, which is not convenient for the promotion and use of this technology. However, there are few reports on the method of OLTC vibration signal location and extraction.
发明内容Contents of the invention
本发明的目的包括提供了一种变压器有载分接开关振动信号提取方法，其能够为OLTC机械状态评估提供基础和支撑。The object of the present invention includes providing a method for extracting a vibration signal of a transformer on-load tap changer, which can provide a basis and support for OLTC mechanical state evaluation.
本发明的实施例可以这样实现：Embodiments of the present invention can be realized like this:
本发明提供一种变压器有载分接开关振动信号提取方法，变压器有载分接开关振动信号提取方法包括：The invention provides a method for extracting a vibration signal of a transformer on-load tap changer. The method for extracting a vibration signal of a transformer on-load tap-changer includes:
S1：对OLTC油箱顶盖或变压器油箱外壳表面的振动进行监测，采集一段数秒长的振动信号；S1: Monitor the vibration of the top cover of the OLTC oil tank or the surface of the transformer oil tank shell, and collect a vibration signal that is several seconds long;
S2：对采集的振动信号进行预处理，得到振动信号片段；S2: Preprocessing the collected vibration signal to obtain a vibration signal segment;
S3：对振动信号片段中每帧振动信号进行傅里叶变换，得到每帧振动信号的频谱图；S3: performing Fourier transform on each frame of the vibration signal in the vibration signal segment to obtain the frequency spectrum of each frame of the vibration signal;
S4：将频谱图划分成多个子频带，分别计算每个子频带的能量；S4: Divide the spectrogram into multiple sub-bands, and calculate the energy of each sub-band respectively;
S5：基于每个子频带的能量，计算每一帧振动信号的能量谱熵；S5: Calculate the energy spectrum entropy of each frame of the vibration signal based on the energy of each sub-frequency band;
S6：设定能量谱熵门限Hthres及持续时间门限Tthres1、Tthres2，逐帧对比，确定信号的开始位置和结束位置；S6: Set the energy spectrum entropy threshold H thres and the duration thresholds T thres1 and T thres2 , compare frame by frame, and determine the start position and end position of the signal;
S7：基于信号的开始位置和结束位置，分离出OLTC振动信号片段。S7: Separate the OLTC vibration signal segment based on the start position and the end position of the signal.
在可选的实施方式中，S1包括：In an optional implementation, S1 includes:
在OLTC进行调压操作时，利用OLTC在线监测系统对OLTC的油箱顶盖或变压器油箱外壳表面的振动信号进行采集，其中，OLTC在线监测系统由电机电流信号通道做触发，同步采集数秒长的振动信号。When the OLTC performs voltage regulation operation, the OLTC online monitoring system is used to collect the vibration signal of the oil tank top cover of the OLTC or the surface of the transformer oil tank shell. Among them, the OLTC online monitoring system is triggered by the motor current signal channel, synchronously collecting several seconds long vibration Signal.
在可选的实施方式中，S2包括：In an optional embodiment, S2 includes:
对采集的振动信号进行零均值、加窗和分帧预处理。Perform zero-mean, windowing and frame preprocessing on the collected vibration signals.
在可选的实施方式中，S2包括：In an optional embodiment, S2 includes:
对采集的振动信号进行零均值处理，去掉信号中存在的直流分量，方法如下所示：Perform zero-mean processing on the collected vibration signal to remove the DC component existing in the signal, the method is as follows:
式中：
在可选的实施方式中，S2包括：In an optional embodiment, S2 includes:
对振动信号进行加窗和分帧预处理，得到振动信号片段，其中，第n时刻的一帧振动信号为：Perform windowing and frame preprocessing on the vibration signal to obtain a vibration signal segment, where the vibration signal of a frame at the nth moment is:
xn＝x*h(n) (2)x n =x*h(n) (2)
式中：xn为信号x取样序列，h(n)为窗函数。Where: x n is the sampling sequence of signal x, and h(n) is the window function.
在可选的实施方式中，在S4中，每个子频带的能量的计算公式如下：In an optional implementation manner, in S4, the calculation formula of the energy of each sub-band is as follows:
式中：Si为每帧振动信号第i个子频带的能量和，M为划分的子频带个数，fj为相应子频带内第j个频率分量幅值，K为每个子频带内频率分量个数。In the formula: S i is the energy sum of the i-th sub-band of each frame vibration signal, M is the number of divided sub-bands, f j is the amplitude of the j-th frequency component in the corresponding sub-band, and K is the frequency component in each sub-band number.
在可选的实施方式中，在S5中，每一帧振动信号的能量谱熵的计算公式如下：In an optional embodiment, in S5, the calculation formula of the energy spectrum entropy of each frame vibration signal is as follows:
式中，pi为每帧振动信号第i个子频带的概率密度函数，pk为每帧振动信号第k个子频带的概率密度函数，H为每帧振动信号的能量谱熵。In the formula, p i is the probability density function of the i-th sub-band of each frame of vibration signal, p k is the probability density function of the k-th sub-band of each frame of vibration signal, and H is the energy spectrum entropy of each frame of vibration signal.
在可选的实施方式中，S6包括：In an optional embodiment, S6 includes:
当某帧信号的能量谱熵大于Hthres、且信号持续时间超过Tthres1时，则判定当前帧是OLTC振动信号的开始位置。When the energy spectrum entropy of a certain frame signal is greater than H thres and the signal duration exceeds T thres1 , it is determined that the current frame is the starting position of the OLTC vibration signal.
在可选的实施方式中，S6包括：In an optional embodiment, S6 includes:
当检测到信号开始后的某帧信号的能量谱熵小于Hthres、且持续时间超过Tthres2仍没有能量谱熵大于Hthres的信号出现时，则判定当前帧是OLTC振动信号的结束位置。When it is detected that the energy spectrum entropy of a certain frame signal after the start of the signal is less than H thres and there is no signal with energy spectrum entropy greater than H thres for a duration exceeding T thres2 , it is determined that the current frame is the end position of the OLTC vibration signal.
在可选的实施方式中，在S6中，Hthres设置为0.5，Tthres1设置为5ms，Tthres2设置为5ms。In an optional implementation manner, in S6, H thres is set to 0.5, T thres1 is set to 5ms, and T thres2 is set to 5ms.
本发明实施例提供的变压器有载分接开关振动信号提取方法的有益效果包括：The beneficial effects of the method for extracting the vibration signal of the transformer on-load tap changer provided by the embodiment of the present invention include:
通过对OLTC油箱顶盖或变压器油箱外壳表面的振动信号进行监测，首先通过零均值处理、加窗和分帧等预处理，对每帧振动信号进行傅里叶变换得到信号频谱图，将频谱图划分为多个子频带并计算每帧信号的能量谱熵，通过设置能量谱熵门限和时间门限获取信号的起点和终点，实现从数秒长的振动信号中分离出毫秒级的OLTC振动信号片段。该方法能自动实现OLTC振动信号提取，便于OLTC在线监测技术的推广和使用，为OLTC机械状态评估提供基础和支撑，具有很好的实用价值。By monitoring the vibration signal on the top cover of the OLTC oil tank or the surface of the transformer oil tank shell, firstly through preprocessing such as zero-mean processing, windowing and framing, the Fourier transform of each frame of the vibration signal is obtained to obtain the signal spectrum, and the spectrum Divide it into multiple sub-bands and calculate the energy spectrum entropy of each frame signal. By setting the energy spectrum entropy threshold and time threshold to obtain the start and end of the signal, it is possible to separate the millisecond-level OLTC vibration signal fragment from the several-second long vibration signal. This method can automatically realize the extraction of OLTC vibration signals, facilitate the promotion and use of OLTC online monitoring technology, and provide the basis and support for OLTC mechanical state evaluation, which has good practical value.
附图说明Description of drawings
为了更清楚地说明本发明实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，应当理解，以下附图仅示出了本发明的某些实施例，因此不应被看作是对范围的限定，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他相关的附图。In order to illustrate the technical solutions of the embodiments of the present invention more clearly, 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 thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.
图1为本发明实施例提供的变压器有载分接开关振动信号提取方法的流程图；Fig. 1 is the flow chart of the transformer on-load tap changer vibration signal extraction method provided by the embodiment of the present invention;
图2为本实施例中采集的振动信号的时域波形图；Fig. 2 is the time-domain waveform diagram of the vibration signal collected in the present embodiment;
图3(a)为本实施例中变压器本体振动信号的频谱图；Fig. 3 (a) is the frequency spectrum diagram of transformer body vibration signal in the present embodiment;
图3(b)为本实施例中OLTC振动信号的频谱图；Fig. 3 (b) is the spectrogram of OLTC vibration signal in the present embodiment;
图4为本实施例中振动信号的能量谱熵；Fig. 4 is the energy spectrum entropy of vibration signal in the present embodiment;
图5为本实施例中自动提取的OLTC振动信号。Fig. 5 is the OLTC vibration signal automatically extracted in this embodiment.
具体实施方式detailed description
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。通常在此处附图中描述和示出的本发明实施例的组件可以以各种不同的配置来布置和设计。In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.
因此，以下对在附图中提供的本发明的实施例的详细描述并非旨在限制要求保护的本发明的范围，而是仅仅表示本发明的选定实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。Accordingly, 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 represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步定义和解释。It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.
在本发明的描述中，需要说明的是，若出现术语“上”、“下”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，或者是该发明产品使用时惯常摆放的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。In the description of the present invention, it should be noted that if the orientation or positional relationship indicated by the terms "upper", "lower", "inner" and "outer" appear, it is based on the orientation or positional relationship shown in the drawings, or It is the orientation or positional relationship that the invention product is usually placed in use, and it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation , and therefore cannot be construed as a limitation of the present invention.
此外，若出现术语“第一”、“第二”等仅用于区分描述，而不能理解为指示或暗示相对重要性。In addition, terms such as "first" and "second" are used only for distinguishing descriptions, and should not be understood as indicating or implying relative importance.
需要说明的是，在不冲突的情况下，本发明的实施例中的特征可以相互结合。It should be noted that, in the case of no conflict, the features in the embodiments of the present invention may be combined with each other.
请参考图1，本实施例提供了一种变压器有载分接开关振动信号提取方法，包括以下步骤：Please refer to FIG. 1. This embodiment provides a method for extracting a vibration signal of a transformer on-load tap-changer, including the following steps:
S1：对OLTC油箱顶盖或变压器油箱外壳表面的振动进行监测，采集一段数秒长的振动信号。S1: Monitor the vibration of the top cover of the OLTC oil tank or the surface of the transformer oil tank shell, and collect a vibration signal that is several seconds long.
具体的，在OLTC进行调压操作时，OLTC在线监测系统对OLTC的油箱顶盖或变压器油箱外壳表面的振动信号进行采集，OLTC在线监测系统由电机电流信号通道做触发，同步采集数秒长的振动信号x＝(x1,x2,···,xN)，该振动信号包括OLTC振动信号片段和变压器本体振动信号片段。Specifically, when the OLTC is performing voltage regulation operations, the OLTC online monitoring system collects the vibration signals of the OLTC’s oil tank top cover or the surface of the transformer oil tank shell, and the OLTC online monitoring system is triggered by the motor current signal channel, synchronously collecting several seconds long vibration Signal x=(x 1 , x 2 ,···,x N ), the vibration signal includes OLTC vibration signal segments and transformer body vibration signal segments.
本实施例中采集的振动信号的时域波形图如图2所示，可以看出OLTC在线监测系统采集的振动信号时长为8s，在5.9～6.1s的时间段内振动信号幅值明显增大，出现一簇冲击振动信号，该时间段信号为OLTC振动信号，其余时间段信号为变压器本体振动信号。The time-domain waveform diagram of the vibration signal collected in this embodiment is shown in Figure 2. It can be seen that the duration of the vibration signal collected by the OLTC online monitoring system is 8s, and the amplitude of the vibration signal increases significantly during the period of 5.9 to 6.1s , a cluster of shock vibration signals appears, the signal in this time period is the OLTC vibration signal, and the signal in the rest of the time period is the vibration signal of the transformer body.
S2：对采集的振动信号进行预处理，得到振动信号片段。S2: Preprocessing the collected vibration signals to obtain vibration signal fragments.
具体的，对采集的振动信号进行零均值、加窗和分帧等预处理。Specifically, preprocessing such as zero-mean, windowing, and framing is performed on the collected vibration signals.
对采集的振动信号进行零均值处理，去掉信号中存在的直流分量，具体方法如下所示：Perform zero-mean processing on the collected vibration signal to remove the DC component existing in the signal. The specific method is as follows:
式中：
对振动信号进行加窗和分帧预处理，得到一帧一帧的振动信号片段，第n时刻的一帧振动信号为：Perform windowing and frame preprocessing on the vibration signal to obtain a frame-by-frame vibration signal segment. The vibration signal of a frame at the nth moment is:
xn＝x*h(n) (2)x n =x*h(n) (2)
式中：xn为信号x取样序列，h(n)为窗函数。Where: x n is the sampling sequence of signal x, h(n) is the window function.
本实施例中窗长为10ms，移帧长度为5ms，得到加窗分帧后的振动信号片段。In this embodiment, the window length is 10 ms, and the frame shifting length is 5 ms, and the vibration signal segment after windowing and frame division is obtained.
S3：对振动信号片段中每帧振动信号进行傅里叶变换，得到每帧振动信号的频谱图。S3: performing Fourier transform on each frame of the vibration signal in the vibration signal segment to obtain a frequency spectrum of each frame of the vibration signal.
本实施例中变压器本体振动信号与OLTC振动信号的频谱图分别如图3(a)和图3(b)所示。可以看出变压器本体振动信号集中在2kHz以内，而OLTC振动信号的频率分布较广，在10kHz～50kHz频率范围内有大量能量分布，且各频率分量幅值大于变压器本体振动信号。Spectrum diagrams of the vibration signal of the transformer body and the vibration signal of the OLTC in this embodiment are shown in Fig. 3(a) and Fig. 3(b) respectively. It can be seen that the vibration signal of the transformer body is concentrated within 2 kHz, while the frequency distribution of the OLTC vibration signal is relatively wide, and there is a large amount of energy distribution in the frequency range of 10 kHz to 50 kHz, and the amplitude of each frequency component is greater than the vibration signal of the transformer body.
S4：将频谱图划分成多个子频带，分别计算每个子频带的能量。S4: Divide the spectrogram into multiple sub-bands, and calculate the energy of each sub-band respectively.
具体的，每个子频带的能量的计算公式如下：Specifically, the formula for calculating the energy of each sub-band is as follows:
式中：Si为每帧振动信号第i个子频带的能量和，M为划分的子频带个数，fj为相应子频带内第j个频率分量幅值，K为每个子频带内频率分量个数。In the formula: S i is the energy sum of the i-th sub-band of each frame vibration signal, M is the number of divided sub-bands, f j is the amplitude of the j-th frequency component in the corresponding sub-band, and K is the frequency component in each sub-band number.
本实施例中将频谱划分为10个子频带，通过公式(3)得到每帧振动信号的各子频带的能量。In this embodiment, the frequency spectrum is divided into 10 sub-frequency bands, and the energy of each sub-frequency band of each frame vibration signal is obtained by formula (3).
S5：基于每个子频带的能量，计算每一帧振动信号的能量谱熵。S5: Calculate the energy spectrum entropy of each frame of the vibration signal based on the energy of each sub-frequency band.
具体的，每一帧振动信号的能量谱熵的计算公式如下：Specifically, the calculation formula of the energy spectrum entropy of each frame vibration signal is as follows:
式中：pi为每帧振动信号第i个子频带的概率密度函数，pk为每帧振动信号第k个子频带的概率密度函数，H为每帧振动信号的能量谱熵。In the formula: p i is the probability density function of the i-th sub-band of the vibration signal of each frame, p k is the probability density function of the k-th sub-band of the vibration signal of each frame, and H is the energy spectrum entropy of the vibration signal of each frame.
本实施例中振动信号的能量谱熵如图4所示，可以看出，本体振动信号的能量谱熵值较小，OLTC振动信号的能量谱熵较大，两者差异明显。The energy spectrum entropy of the vibration signal in this embodiment is shown in Figure 4. It can be seen that the energy spectrum entropy of the body vibration signal is small, and the energy spectrum entropy of the OLTC vibration signal is large, and the difference between the two is obvious.
S6：设定能量谱熵门限Hthres及持续时间门限Tthres1、Tthres2，逐帧对比，确定信号的开始位置和结束位置。S6: Setting the energy spectrum entropy threshold H thres and the duration thresholds T thres1 , T thres2 , and comparing them frame by frame to determine the start position and end position of the signal.
具体的，当某帧信号的能量谱熵大于Hthres时，当前帧则可能是信号的开始位置。由于噪声一般是突发的，持续时间不长，设定信号持续时间门限Tthres1，当信号持续时间超过Tthres1时，则认为OLTC振动信号开始。本实施例中能量谱熵门限Hthres设置为0.5，信号持续时间门限Tthres1设置为5ms。Specifically, when the energy spectrum entropy of a certain frame signal is greater than H thres , the current frame may be the starting position of the signal. Since the noise is generally sudden and does not last long, a signal duration threshold T thres1 is set. When the signal duration exceeds T thres1 , it is considered that the OLTC vibration signal starts. In this embodiment, the energy spectrum entropy threshold H thres is set to 0.5, and the signal duration threshold T thres1 is set to 5 ms.
当检测到信号开始后的某帧信号的能量谱熵小于Hthres时，当前帧可能是信号的结束位置。由于OLTC振动信号存在多个冲击段，基于冲击段间的持续时间设定时间门限Tthres2，当持续时间超过Tthres2时间内仍没有能量谱熵大于Hthres的信号出现，则认为OLTC振动信号结束。本实施例中时间门限Tthres2设置为5ms。When it is detected that the energy spectrum entropy of a frame signal after the start of the signal is less than H thres , the current frame may be the end position of the signal. Since there are multiple impact segments in the OLTC vibration signal, the time threshold T thres2 is set based on the duration between the impact segments. When the duration exceeds T thres2 and there is still no signal with an energy spectrum entropy greater than H thres , the OLTC vibration signal is considered to be over . In this embodiment, the time threshold T thres2 is set to 5 ms.
S7：基于信号的开始位置和结束位置，分离出OLTC振动信号片段。S7: Separate the OLTC vibration signal segment based on the start position and the end position of the signal.
本实施例中自动提取的OLTC振动信号时如图5所示，可以看出本方法能准确、有效提取出OLTC振动信号。The OLTC vibration signal automatically extracted in this embodiment is shown in FIG. 5 , and it can be seen that the method can accurately and effectively extract the OLTC vibration signal.
本实施例提供的变压器有载分接开关振动信号提取方法的有益效果包括：The beneficial effects of the method for extracting the vibration signal of the transformer on-load tap-changer provided in this embodiment include:
OLTC在线监测系统通过对OLTC油箱顶盖或变压器油箱外壳表面的振动信号进行监测，首先通过零均值处理、加窗和分帧等预处理，对每帧振动信号进行傅里叶变换得到信号频谱图，将频谱图划分为多个子频带并计算每帧信号的能量谱熵，通过设置能量谱熵门限和时间门限获取信号的起点和终点，实现从数秒长的振动信号中分离出毫秒级的OLTC振动信号片段。该方法能自动实现OLTC振动信号提取，便于OLTC在线监测技术的推广和使用，为OLTC机械状态评估提供基础和支撑，具有很好的实用价值。The OLTC online monitoring system monitors the vibration signal on the top cover of the OLTC oil tank or the surface of the transformer oil tank shell. First, through preprocessing such as zero-mean processing, windowing, and frame division, the vibration signal of each frame is Fourier transformed to obtain the signal spectrum. , divide the spectrogram into multiple sub-bands and calculate the energy spectrum entropy of each frame signal, and obtain the start and end of the signal by setting the energy spectrum entropy threshold and time threshold, so as to separate the millisecond-level OLTC vibration from the vibration signal that is several seconds long signal fragment. This method can automatically realize the extraction of OLTC vibration signals, facilitate the promotion and use of OLTC online monitoring technology, and provide the basis and support for OLTC mechanical state evaluation, which has good practical value.
以上，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以权利要求的保护范围为准。The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention shall be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.
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