CN202735426U - GIS fault diagnosis system based on vibration signal spectral analysis - Google Patents

Abstract

The utility model discloses a GIS fault diagnosis system based on frequency spectrum analysis of vibration signals, which belongs to the field of GIS fault monitoring. The system includes a series connection of vibration acceleration sensors, charge amplifiers, data acquisition instruments and PCs. The vibration acceleration sensors include three vibration sensors respectively fixed on the outer surface of the GIS box in the directions of X, Y and Z axes. The system uses three vibration sensors to collect GIS vibration signals in the directions of X, Y, and Z axes, preprocesses the vibration signals, and then performs spectrum analysis to calculate the energy at the characteristic frequency, and compare the calculated value with the normal state. Comparison, according to the comparison result combined with the threshold to determine the GIS failure. The utility model has the advantages of simple engineering realization, accurate diagnosis and high reliability.

Description

GIS Fault Diagnosis System Based on Vibration Signal Spectrum Analysis

technical field

The utility model relates to an on-line monitoring technology for the status of power transmission and transformation equipment, in particular to a fault diagnosis system for gas-insulated metal-enclosed switchgear (GIS), which belongs to the field of GIS fault monitoring.

Background technique

Gas-insulated metal-enclosed switchgear (GIS) was born in the early 1970s. It is a combination of electrical components such as circuit breakers, disconnectors, fast earthing switches, current transformers, lightning arresters, busbars, bushings, and cable terminals. In the metal shell, the interior is filled with 0.3~0.4MPa SF6 gas as the insulating medium.

The role of GIS is equivalent to a switch station, which has the advantages of small size, small footprint, high operational reliability, no influence from external environment, flexible configuration, small maintenance workload, long maintenance cycle, and no electromagnetic interference. Favored by power companies, it is widely used in the construction and transformation of urban power grids.

Due to the strong electronegative properties of SF6 gas, it has good insulating properties. The current ultra-high voltage and ultra-high voltage equipment mainly use SF6 as the insulating medium. However, once the local field strength is too concentrated due to the mixing of water, impurities, particles or other reasons in SF6 gas, its insulation performance will drop sharply. Therefore, there are high requirements for the production process, conditions and environment of GIS. However, in the process of GIS manufacturing and assembly, defects will inevitably be left, which leaves hidden troubles for GIS. Today, with the increasing demand for electricity, real-time status monitoring of important electrical equipment can not only ensure the continuity of power supply and long-term safe and stable operation of equipment, but also a necessary link to improve economic benefits in the power industry.

Due to the opening and closing vibration of switches and knife switches during the manufacture, transportation, installation and operation of GIS equipment, conductive impurities such as metal particles, powder and moisture will be formed inside, which is the main cause of GIS equipment failure.

Currently there are several GIS fault diagnosis methods:

1. The ultra-high frequency detection method can perform fault diagnosis according to the waveform characteristics of the discharge pulse and the spectrum characteristics of the UHF signal. It has good detection sensitivity, but the structural design of the ultra-high frequency sensor itself cannot suppress the interference from the high frequency band in the substation. This has seriously affected the accuracy of the detection results.

2. The high-frequency grounding current method uses well-made sensors to maintain good transmission characteristics in a wide frequency range, but the ground wire needs to pass through the coil, which makes on-site installation extremely inconvenient.

3. The optical measurement method does not have the problem of anti-interference, but the sensitivity is very low and a large number of sensors are required, so the method is not practical.

Utility model content

Aiming at the defects in the prior art, the utility model proposes an easy-to-implement and accurate diagnosis GIS fault diagnosis system based on frequency spectrum analysis of vibration signals.

The GIS fault diagnosis system includes a vibration acceleration sensor, a charge amplifier, a data acquisition instrument and a PC, wherein: the vibration acceleration sensor is fixed on the outer surface of the GIS box, the output of the vibration acceleration sensor is connected to the charge amplifier, and the charge amplifier is electrically converted through BNC The interface is connected to the data acquisition instrument, and the data acquisition instrument is connected to the PC through the network cable interface.

The vibration acceleration sensor adopts magnet adsorption and is fixed on the outer surface of the GIS box body, and the vibration acceleration sensor includes three vibration acceleration sensors, and the three vibration acceleration sensors are respectively fixed on the X, Y and Z axis directions of the GIS box outer surface superior.

Technical effect:

1. The system structure is simple, easy to implement, and the implementation cost is low.

2. There is no connection between the sensor and the electrical circuit of the GIS equipment, and there is no electrical interference, which greatly improves the accuracy and reliability of diagnosis.

Description of drawings

Fig. 1 is a structural block diagram of the diagnostic system of the present invention.

Fig. 2 is a schematic diagram of the installation position of the vibration acceleration sensor.

Fig. 3 is a flowchart of the diagnosis method adopted by the utility model.

Figure 4(a) is the time-domain spectrum diagram of the vibration signal before wavelet noise reduction; Figure 4(b) is the time-domain spectrum diagram of the vibration signal after wavelet noise reduction.

Figure 5(a), Figure 5(b), and Figure 5(c) are the vibration signal spectrum diagrams in the X, Y and Z axis directions when the GIS is running normally.

Figure 6 is a schematic diagram of the vibration spectrum when various internal faults occur in GIS. The numbers in the frame in the figure: 1 indicates vibration caused by partial discharge; 2 indicates vibration caused by foreign objects; 3 indicates vibration caused by electromagnetic force and magnetostriction; 4 indicates vibration caused by electrostatic force 5 means vibration caused by operation; 6 means vibration caused by short circuit to ground.

Detailed ways

Below the utility model is described further.

The structure of the GIS fault diagnosis system of the utility model is shown in Figure 1, including a vibration acceleration sensor, a charge amplifier, a data acquisition instrument and a PC, wherein: the vibration acceleration sensor is firmly adsorbed (fixed) on the outer surface of the GIS box by a magnet , the output end of the vibration acceleration sensor is connected to the charge amplifier, the charge amplifier is connected to the data acquisition instrument through the BNC electrical conversion interface, and the data acquisition instrument is connected to the PC through the network cable interface. The vibration acceleration sensor cooperates with the charge amplifier to measure vibration signals. The data acquisition instrument is used to collect and record the detected vibration signals. The PC is used to store, process and diagnose the signal data output by the data acquisition instrument, and display diagnostic result.

In order to comprehensively monitor the vibration on the surface of the GIS, three vibration acceleration sensors are respectively fixed on the outer surface of the GIS box in the X, Y and Z axis directions. The specific fixed positions are shown in Figure 2.

The diagnostic method flow chart of the present utility model is as shown in Figure 3, specifically comprises the following steps:

Step 1: Set the sampling frequency to 10kHz and the sampling time to 1 second;

Step 2: start to collect vibration signals of GIS when GIS is running stably;

Step 3: Sampling the vibration signal, in the sampled data, according to the sampling time, sampling frequency, and number of sampling points, the vibration signal is intercepted with an integer multiple period;

Step 4: Perform wavelet noise reduction on the vibration signal intercepted throughout the period;

Step 5: Perform spectrum analysis on the signal segment after noise reduction;

Step 6: Calculate the energy at a frequency of 50Hz, and define this energy as feature 1; calculate the energy sum of energies at frequencies of 100Hz, 200Hz, and 300Hz, and define this energy sum as feature 2;

Step 7: When feature 1 is reduced by more than 50% compared with the normal state, go to step 8, otherwise go to step 3;

Step 8: When feature 2 increases by more than 100% compared with the normal state, go to step 9, otherwise go to step 3;

Step 9: Calculate the ratio of feature two to feature one, and define the ratio as feature three;

Step 10: Compare feature 3 with the set threshold, when feature 3 is smaller than the threshold, go to step 3, otherwise it is determined that the GIS is malfunctioning.

An embodiment of the present utility model is provided below:

Taking the GIS of Jiangdongmen 110KV substation of Jiangsu Electric Power Company as the experimental object, the hardware system was built according to the requirements. The hardware selection is as follows: the vibration acceleration sensor adopts CA-YD-103, the charge amplifier adopts KD5002, the data acquisition instrument adopts Nicolet7700, PC machine using a laptop.

The experiment was carried out according to the steps of the above diagnosis method. The original vibration signal collected in the experiment in the normal operation state of GIS is shown in Figure 4(a). The wavelet noise reduction was performed on the original vibration signal, and the vibration signal after noise reduction was shown in Figure 4(b) ), comparing Figure 4(a) and Figure 4(b), we can clearly see the noise reduction effect.

The vibration signals in the directions of X, Y and Z axes when the GIS is running normally are shown in Fig. 5(a), (b) and (c) respectively. Comparing Fig. 5(a), (b) and (c), it can be found that In the signal spectrum during normal operation of GIS, the vibration is most obvious and the energy is the largest at 50Hz, while the energy at 100Hz, 200Hz, and 300Hz is relatively small. After calculation, the energy value (normalized) at the characteristic frequency of the vibration signal of the measured GIS is shown in Table 1.

Table 1

Theoretical analysis shows that when a fault occurs inside the GIS, the vibration signal is mainly manifested in high-frequency signals, as shown in Figure 6, so that the energy at the fundamental frequency of 50 Hz will be relatively reduced, and the energy sum at high frequencies of 100 Hz, 200 Hz, and 300 Hz will increase significantly. If the ratio of the energy at 100Hz, 200Hz, 300Hz to the energy at 50Hz reaches or exceeds 1, it is determined that an internal fault occurs in the GIS. Fault.

Claims (3)

1. GIS fault diagnosis system based on the vibration signal spectrum analysis, it is characterized in that: involving vibrations acceleration transducer, charge amplifier, data collecting instrument and PC, wherein: vibration acceleration sensor is fixed in the outside surface of GIS casing, the output terminal of vibration acceleration sensor connects charge amplifier, charge amplifier is by BNC electric conversion interface connection data Acquisition Instrument, and data collecting instrument connects PC by cable interface.

2. the GIS fault diagnosis system based on the vibration signal spectrum analysis according to claim 1 is characterized in that: described vibration acceleration sensor is to adopt magnet adsorption to be fixed in the outside surface of GIS casing.

3. the GIS fault diagnosis system based on the vibration signal spectrum analysis according to claim 1 and 2, it is characterized in that: described vibration acceleration sensor comprises three vibration acceleration sensors, and three vibration acceleration sensors are individually fixed on X, the Y and Z-direction of GIS box outer surface.

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