Method for diagnosing looseness of connecting bolt of combined electric appliance base

Abstract

The invention belongs to the technical field of power transmission and transformation equipment fault diagnosis, and relates to a method for diagnosing looseness of a base connecting bolt of a combined electric appliance. And whether the base connecting bolt is loosened or not is judged by comparing the change of the proportion of the characteristic frequency amplitude in the full frequency band under different working conditions. According to the invention, whether the connecting bolt between the combined electric appliance and the supporting base is loosened or not can be accurately judged. The method is simple, convenient and rapid, has high accuracy, has no electrical connection with the equipment, and has no influence on the running state of the equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of fault diagnosis of power transmission and transformation equipment, in particular to a method for diagnosing loosening of connecting bolts of a combined electrical appliance base. Background Art

[0002] Gas-insulated combined electrical equipment is a complete set of electrical devices composed of a variety of high-voltage electrical installation main wiring and system functions. It uses a cylinder filled with high-voltage SF6 insulating gas to encapsulate common substation equipment such as busbars, voltage transformers, current transformers, lightning arresters, disconnectors, circuit breakers, etc., thereby achieving strong systematization, high integration, small footprint, good reliability, etc., and is widely used in power systems of various voltage levels from 66 to 1000 kV.

[0003] Although combined electrical appliances are highly reliable, various faults are emerging with the increasing usage. One of the most common and harmful faults is loose base connection bolts. The support base is the foundation of the entire combined electrical equipment. Once the connection bolts are loose, the support stability will soon decrease, which will cause the structural stress of the combined electrical equipment to increase, greatly increasing the possibility of sulfur hexafluoride gas leakage in each connection flange, and also increasing the failure rate of equipment such as transformers and disconnectors. Therefore, being able to detect loose base connection bolts as early as possible is very important for ensuring the safety of combined electrical equipment. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies in the prior art and to propose a method for diagnosing loose connection bolts on a combination electrical appliance base, which can accurately determine whether the connection bolts between the combination electrical appliance and the support base are loose.

[0005] Early loosening of bolts will not generate electrical signals, but will generate vibration signals, so vibration signal testing of the combination electrical support base is the best way to detect loosening faults early.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] The main principle of the present invention is to judge whether the base connection bolts are loose by comparing the changes in the proportion of the characteristic frequency amplitude in the whole frequency band under different working conditions.

[0008] A method for diagnosing loosened connection bolts on a combination electrical appliance base uses the change in vibration signals when loosened connection bolts occur in a GIS to monitor faults. The specific steps are as follows:

[0009] Step 1: Attach the vibration sensor to the connection bolts of the GIS base to be tested;

[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: Get the full-frequency vibration amplitude a at this time;

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

[0013] Step 5: Calculate the percentage of the vibration amplitude in the frequency range above 2200Hz in the spectrum to the total frequency amplitude 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: Get the full-frequency vibration amplitude A at this time;

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

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

[0018] Step 10: Compare the size relationship between n1 and N1. If N1-n1≥10%, it is determined that the base connection bolts are loose. If N1-n1<10%, it is determined that the base connection bolts are not loose.

[0019] Furthermore, an acceleration vibration sensor with a sensitivity of ≤500mV / g is selected, the sampling frequency of the collector is 12kHz, and the sampling time is 5s. When the base connection bolts of the GIS are loose, abnormal vibration will occur at the bolt position, so a ferromagnetic sensor can be used to adsorb or adhere to the bolt.

[0020] Furthermore, the vibration sensor is connected to an industrial computer, which includes a computing unit, a storage unit, an output unit, etc. It can collect vibration signals of 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 full frequency range.

[0021] The present invention has obtained the vibration characteristics of the combination electrical appliance when the base connection bolts are loose in the laboratory simulation test. It has been verified through experiments that when the operating current is increased, the vibration amplitude at the connection bolts will increase significantly, and the proportion of frequency components above 2200Hz will increase significantly. After many experiments, quantitative indicators were obtained, and a diagnosis method for the loose connection bolts of the combination electrical appliance base was formed, which can quickly and efficiently determine whether the connection bolts of the combination electrical appliance base are loose.

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

[0023] 1. The present invention innovatively proposes a method for diagnosing loose connection bolts of a combination electrical appliance base, which can accurately determine whether the connection bolts between the combination electrical appliance and the support base are loose.

[0024] 2. The method proposed by the present invention is simple, fast, highly accurate, has no electrical connection with the equipment, and has no effect on the operating state of the equipment.

[0025] 3. The method proposed in the present invention innovatively introduces vibration testing technology into electrical equipment fault diagnosis. Compared with electrical testing methods, it is more sensitive and can detect potential faults earlier. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0027] Figure 2 It is an operation step diagram of the present invention. DETAILED DESCRIPTION

[0028] The following is a further detailed description of the implementation of the present invention in conjunction with the accompanying drawings. The following embodiments are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0029] Taking the support base of the 2215A interval lightning arrester of a certain substation combination electrical appliance as an example, during the inspection, it was found that the support base had problems with excessive vibration and noise, and it was suspected that its connecting bolts were loose, so a vibration test was carried out on it.

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

[0031] Step 1: Attach the vibration sensor to the connection bolts of the GIS base to be tested. For specific locations, see 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: Get the full frequency vibration amplitude a=8m / s 2 ;

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

[0035] Step 5: Calculate the percentage of the vibration amplitude in the frequency range above 2200Hz in the spectrum to 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: Get the full frequency vibration amplitude A = 10m / s 2 ;

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

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

[0040] Step 10: Compare the size relationship between n1 and N1, N1-n1=50%-25%≥10%, so it is determined that the base connection bolts are loose. See the operation steps diagram Figure 2 .

[0041] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept, which all belong to the protection scope of the present invention.

Claims

1. A method for diagnosing loose bolts on a combination electrical appliance base, characterized in that: The change of vibration signal when the base connection bolts are loose is used to monitor the fault, and whether the base connection bolts are loose is determined by comparing the changes in the proportion of characteristic frequency amplitude in the full frequency band under different working conditions.

2. The method for diagnosing loosened connection bolts of a combination electrical appliance base according to claim 1, characterized in that: The specific steps are as follows: Step 1: Attach the vibration sensor to the connection bolts of the GIS base to be 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: Get the full-frequency vibration amplitude a at this time; Step 4: Perform fast Fourier transform on the vibration signal and calculate the vibration amplitude a1 in the frequency range above 2200 Hz in the spectrum; Step 5: Calculate the percentage of the vibration amplitude in the frequency range above 2200Hz in the spectrum to the total frequency amplitude n1 = a1 / 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: Get the full-frequency vibration amplitude A at this time; Step 8: Perform fast Fourier transform on the vibration signal and calculate the vibration amplitude A1 in the frequency range above 2200 Hz in the spectrum; Step 9: Calculate the percentage of the vibration amplitude in the frequency range above 2200Hz in the spectrum to the total frequency amplitude N1 = A1 / A; Step 10: Compare the size relationship between n1 and N1. If N1-n1≥10%, it is determined that the base connection bolts are loose. If N1-n1<10%, it is determined that the base connection bolts are not loose.

3. The method for diagnosing loosened bolts of a combination electrical appliance base according to claim 2, 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.

4. The method for diagnosing loosened connection bolts of a combination electrical appliance base according to claim 3, characterized in that: The vibration sensor is a ferromagnetic sensor, which is adsorbed or adhered to the bolt.

5. The method for diagnosing loosened connection bolts of a combination electrical appliance base according to claim 4, characterized in that: The vibration sensor is connected to an industrial computer, which includes a computing unit, a storage unit, and an output unit. The industrial computer can collect vibration signals of 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 full frequency band.

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