A method for diagnosing loose connection bolts of a combination electrical appliance base

Abstract

This invention belongs to the field of fault diagnosis technology for power transmission and transformation equipment, and relates to a method for diagnosing loose connecting bolts on the base of combined electrical appliances. It monitors the fault by observing changes in vibration signals when the base connecting bolts are loose, and determines whether the base connecting bolts are loose by comparing the changes in the proportion of characteristic frequency amplitude across the entire frequency band under different operating conditions. This invention can accurately determine whether there is a loose connecting bolt between the combined electrical appliance and the supporting base. The method is simple, fast, and highly accurate, has no electrical connection to the equipment, and has no impact on the equipment's operating status.

Description

Technical Field

[0001] This invention belongs to the field of fault diagnosis technology for power transmission and transformation equipment, and in particular, it is a method for diagnosing loose connecting bolts on the base of a combined electrical appliance. Background Technology

[0002] Gas-insulated switchgear is a complete electrical device composed of various high-voltage electrical appliances, main wiring, and system functions. It encapsulates commonly used substation equipment such as busbars, voltage transformers, current transformers, surge arresters, disconnectors, and circuit breakers within a cylinder filled with high-voltage SF6 insulating gas. This results in a system with strong system integration, small footprint, and high reliability, making it widely used in power systems of various voltage levels from 66 to 1000 kV.

[0003] Although combined electrical equipment (CEAs) are highly reliable, various malfunctions are emerging as their usage increases. One very common and serious malfunction is loose base connection bolts. The support base is the foundation of the entire CEA. Once the connection bolts become loose, the support stability will quickly decrease, leading to increased structural stress on the CEA. This greatly increases the possibility of sulfur hexafluoride (SF6) gas leakage from the various connection flanges, and also increases the failure rate of equipment such as instrument transformers and disconnect switches. Therefore, early detection of loose base connection bolts is crucial for ensuring the safety of CEAs. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for diagnosing loose connecting bolts on the base of a combined electrical appliance, which can accurately determine whether there is a loose connecting bolt fault between the combined electrical appliance and the support base.

[0005] Early-stage bolt loosening will not generate electrical signals, but it will generate vibration signals. Therefore, vibration signal testing of the combined electrical appliance support base is the best way to detect loosening faults as early as possible.

[0006] The technical problem solved by this invention is achieved through the following technical solution:

[0007] The main principle of this invention is to determine whether the base connecting bolts have become loose by comparing the changes in the proportion of characteristic frequency amplitude across the entire frequency band under different operating conditions.

[0008] A method for diagnosing loose connecting bolts on the base of a combined electrical appliance utilizes changes in vibration signals when the GIS (Gas Insulated Switchgear) base connecting bolts become loose to monitor the fault. The specific steps are as follows:

[0009] Step 1: Attach the vibration sensor to the connecting bolt of the GIS base under test;

[0010] Step 2: Adjust the GIS operating current to 50% of the maximum rated current, and collect vibration signals after the operating conditions stabilize;

[0011] Step 3: Obtain the full-frequency vibration amplitude 'a' at this point;

[0012] Step 4: Perform a fast Fourier transform on the vibration signal to calculate the vibration amplitude a1 in the frequency range above 2200Hz in the spectrum;

[0013] Step 5: Calculate the percentage of vibration amplitude in the frequency range above 2200Hz in the spectrum, n1 = a1 / a;

[0014] Step 6: Adjust the GIS operating current to 100% of the maximum rated current, and collect vibration signals after the operating conditions stabilize.

[0015] Step 7: Obtain the full-frequency vibration amplitude A at this point;

[0016] Step 8: Perform a fast Fourier transform on the vibration signal and calculate the vibration amplitude A1 in the frequency range above 2200Hz in the spectrum;

[0017] Step 9: Calculate the percentage of vibration amplitude in the frequency range above 2200Hz in the total frequency amplitude N1 = A1 / A;

[0018] Step 10: Compare the magnitudes of n1 and N1. If N1-n1≥10%, it is determined that the base connecting bolt is loose. If N1-n1<10%, it is determined that the base connecting bolt is not loose.

[0019] Furthermore, an acceleration vibration sensor with a sensitivity ≤500mV / g is selected, the data acquisition instrument has a sampling frequency of 12kHz, and the sampling time is 5s. When the GIS base connecting bolts become loose, abnormal vibration will occur at the bolt location. Therefore, a ferromagnetic sensor can be used, which can be adsorbed or adhered to the bolt.

[0020] Furthermore, the vibration sensor is connected to an industrial control computer, which includes a computing unit, a storage unit, and an output unit. It can acquire vibration signals from the GIS in real time and perform a fast Fourier transform on the acquired signals to calculate the vibration amplitude at each frequency and its proportion across the entire frequency range.

[0021] This invention has obtained the vibration characteristics of a combined electrical appliance with loose base connecting bolts in laboratory simulation tests. Experimental verification showed that the vibration amplitude at the connecting bolts increased significantly when the operating current was increased, and the proportion of frequency components above 2200Hz also increased significantly. Quantitative indicators were obtained through multiple experiments, forming a diagnostic method for loose base connecting bolts in combined electrical appliances, which can quickly and efficiently determine whether the base connecting bolts of combined electrical appliances are loose.

[0022] The advantages and positive effects of this invention are:

[0023] 1. This invention innovatively proposes a method for diagnosing loose connecting bolts on the base of a combined electrical appliance, which can accurately determine whether there is a loose connecting bolt fault between the combined electrical appliance and the support base.

[0024] 2. The method proposed in this invention is simple, fast, and highly accurate. It has no electrical connection with the equipment and has no impact on the equipment's operating status.

[0025] 3. The method proposed in this invention innovatively introduces vibration testing technology into the fault diagnosis of electrical equipment. Compared with electrical testing methods, it is more sensitive and can detect potential faults earlier. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the sensor installation of the present invention;

[0027] Figure 2 This is a diagram illustrating the operational steps of the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.

[0029] Taking the surge arrester support base of the 2215A bay of the combined electrical equipment in a certain substation as an example, the support base was found to have excessive vibration and noise during the inspection process, and it was suspected that the connecting bolts were loose, so vibration testing was carried out on it.

[0030] According to the method of the present invention:

[0031] Step 1: Attach the vibration sensor to the connecting bolts of the GIS base being tested. See [link to specific location] for details. Figure 1 ;

[0032] Step 2: Adjust the GIS operating current to 50% of the maximum rated current, and collect vibration signals after the operating conditions stabilize;

[0033] Step 3: Obtain the full-frequency vibration amplitude at this point, a = 8 m / s². 2 ;

[0034] Step 4: Perform a Fast Fourier Transform on the vibration signal and calculate the vibration amplitude a1 = 2 m / s in the frequency range above 2200 Hz in the spectrum. 2 ;

[0035] Step 5: Calculate the percentage of vibration amplitude in the frequency range above 2200Hz in the total frequency amplitude, n1 = a1 / a = 25%;

[0036] Step 6: Adjust the GIS operating current to 100% of the maximum rated current, and collect vibration signals after the operating conditions stabilize.

[0037] Step 7: Obtain the full-frequency vibration amplitude A = 10 m / s at this point. 2 ;

[0038] Step 8: Perform a Fast Fourier Transform on the vibration signal and calculate the vibration amplitude A1 = 5 m / s in the frequency range above 2200 Hz in the spectrum. 2 ;

[0039] Step 9: Calculate the percentage of vibration amplitude in the frequency range above 2200Hz in the total frequency amplitude N1 = A1 / A = 50%;

[0040] Step 10: Compare the magnitudes of n1 and N1. N1 - n1 = 50% - 25% ≥ 10%, therefore, it is determined that the base connecting bolt is loose. See the operation step diagram. Figure 2 .

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept, and these all fall within the protection scope of the present invention.

Claims

1. A method for diagnosing loose connecting bolts on the base of a combined electrical appliance, characterized in that, Fault monitoring is performed by observing changes in vibration signals when the base connecting bolts are loose. The determination of whether the base connecting bolts are loose is made by comparing the changes in the proportion of characteristic frequency amplitude across the entire frequency band under different operating conditions. The specific steps are as follows: Step 1: Attach the vibration sensor to the connecting bolt of the GIS base being tested; Step 2: Adjust the GIS operating current to 50% of the maximum rated current, and collect vibration signals after the operating conditions stabilize; Step 3: Obtain the full-frequency vibration amplitude at this point. a ; Step 4: Perform a Fast Fourier Transform on the vibration signal to calculate the vibration amplitude in the frequency range above 2200Hz in the spectrum. a 1; Step 5: Calculate the percentage of vibration amplitude in the frequency range above 2200Hz in the total frequency spectrum. n 1= a 1 / a ; Step 6: Adjust the GIS operating current to 100% of the maximum rated current, and collect vibration signals after the operating conditions stabilize. Step 7: Obtain the full-frequency vibration amplitude at this point. A ; Step 8: Perform a Fast Fourier Transform on the vibration signal to calculate the vibration amplitude in the frequency range above 2200Hz in the spectrum. A 1; Step 9: Calculate the percentage of vibration amplitude in the frequency range above 2200Hz in the total frequency spectrum. N 1= A 1 / A ; Step 10: Comparison n 1 and N The size relationship of 1, if N 1- n If 1% ≥ 10%, it is determined that the base connecting bolts are loose. N 1- n If 1% < 10%, it is determined that the base connection bolts are not loose.

2. The method for diagnosing loose connecting bolts on the base of a combined electrical appliance according to claim 1, characterized in that, The vibration sensor is an acceleration vibration sensor with a sensitivity of ≤500mV / g, a sampling frequency of 12kHz, and a sampling time of 5s.

3. The method for diagnosing loose connecting bolts on the base of a combined electrical appliance according to claim 2, characterized in that, The vibration sensor is a ferromagnetic sensor that is adsorbed or adhered to the bolt.

4. The method for diagnosing loose connecting bolts on the base of a combined electrical appliance according to claim 3, characterized in that, The vibration sensor is connected to an industrial control computer, which includes a computing unit, a storage unit, and an output unit. It can collect vibration signals from the GIS in real time, perform fast Fourier transform on the collected signals, and calculate the vibration amplitude at each frequency and its proportion in the entire frequency range.

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