Novel EFPI sensor and installation method of novel EFPI sensor in large-scale motor stator slot

Abstract

The invention relates to the technical field of sensors, and discloses a novel EFPI sensor and an installation method of the novel EFPI sensor in a large-scale motor stator slot, the novel EFPI sensor is based on Michelson and Fabry-Perot interference principles, MEMS processing is adopted to prepare an acoustic sensitive diaphragm with a phase adjusting groove and a pressure balance hole, and the acoustic sensitive diaphragm is used for detecting the phase adjusting groove and the pressure balance hole. A diaphragm type EFPI acoustic emission sensor with temperature and pressure self-adaption is established by combining an optical fiber collimating mirror; when the diaphragm is forced to vibrate, the deflection of different positions of the diaphragm is different, so that the optical path difference of reflected light is unequal, the phase difference of reflected light signals is generated, finally, the interference intensity emission of the reflected light signals is changed, and the detected ultrasonic signal is restored through the change of the light intensity. According to the diaphragm type EFPI acoustic emission sensor, stacked high-permeability silicon steel sheets are adopted to construct an EFPI sensor Fabry-Perot cavity supporting structure, selection of the installation position of a generator stator groove EFPI sensor has no influence on large generator stator magnetic field distribution, and the problem that local magnetic field gathering causes too high eddy current damage is solved.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, and in particular to a novel EFPI sensor and a method for installing the sensor in a stator slot of a large motor. Background Art

[0002] Partial discharge is the main factor that induces insulation damage, which can easily cause operating accidents and huge economic losses. Comprehensive detection of partial discharge can quickly determine the insulation status of large power equipment, which has been the research focus of experts and scholars at home and abroad for many years. Among the many partial discharge detection technologies, the partial discharge acoustic detection method has the unique advantages of strong anti-electromagnetic interference ability, effective isolation of low-frequency vibration on site in the detection frequency band, and accurate positioning of partial discharge points.

[0003] However, the traditional piezoelectric ceramic partial discharge ultrasonic sensor (PZT) cannot be used under the high field strength conditions inside large power equipment due to its own structural characteristics. The new extrinsic fiber Fabry-Perot (EFPI) partial discharge acoustic emission sensor has a small structure, does not contain metal components inside, has a fully insulated structure, and relies on optical signals for signal transmission, so it is not interfered by the strong electromagnetic field of large power equipment. It can be installed and used inside the equipment to obtain better detection conditions, and relies on its own high-sensitivity detection characteristics to effectively detect partial discharge ultrasonic signals to ensure the safe and stable operation of power equipment. However, there is still a lack of key technical guidance on the installation method of the sensor in the stator structure of large generators, and how to avoid additional influence on the stator magnetic field of large generators, resulting in excessive eddy current damage caused by local magnetic field accumulation. Summary of the invention

[0004] In view of the above problems, the present invention proposes a novel EFPI sensor and a method for installing the sensor in a stator slot of a large motor.

[0005] The technical solution adopted by the present invention is: A novel EFPI sensor is provided. The novel EFPI sensor is based on the Michelson and Fabry-Perot interference principle. A sound-sensitive diaphragm with a phase adjustment groove and a pressure balance hole is prepared by MEMS processing. A temperature and pressure adaptive diaphragm-type EFPI acoustic emission sensor is established in combination with a fiber optic collimator. When the diaphragm is forced to vibrate, the disturbances at different positions of the diaphragm are different, resulting in unequal optical path differences of reflected light, which causes a phase difference in the reflected light signal, and ultimately causes the emission change of the interference intensity of the reflected light signal. The measured ultrasonic signal is restored by the change in light intensity.

[0006] Furthermore, the diaphragm-type EFPI acoustic emission sensor includes a high magnetic permeability silicon steel sheet support structure, which adopts a laminated silicon steel sheet, a diaphragm is installed on its front end surface, and the front end surface of the high magnetic permeability silicon steel sheet is recessed inward to form a Fabry-Perot cavity, and an optical fiber line 5 extending to the Fabry-Perot cavity is installed on its rear side.

[0007] Furthermore, the ferromagnetic properties of the silicon steel sheet are consistent with the ferromagnetic properties of the silicon steel sheet in the stator slot of the generator, thereby reducing and detecting the air gap structure.

[0008] Furthermore, the core diameter of the optical fiber is 0.25 mm.

[0009] Furthermore, the thickness of the Fabry-Perot cavity is 0.1 mm.

[0010] Furthermore, the diaphragm is a quartz diaphragm with a thickness of 0.02 mm.

[0011] A method for installing a novel EFPI sensor in a stator slot of a large motor. The method is based on the novel EFPI sensor. When determining the installation position of the diaphragm EFPI acoustic emission sensor in the stator slot of a large motor, the Fabry-Perot cavity and the quartz diaphragm structure of the diaphragm EFPI acoustic emission sensor are both close to the end face of the electrode stator slot; at the same time, the laminated silicon steel sheets of the diaphragm EFPI acoustic emission sensor are parallel to the laminated silicon steel sheets of the generator stator.

[0012] The beneficial effects of the present invention are: This new EFPI sensor is based on the Michelson and Fabry-Perot interference principles. It uses MEMS processing to prepare a sound-sensitive diaphragm with a phase adjustment groove and a pressure balance hole, and combines it with a fiber optic collimator to establish a temperature and pressure adaptive diaphragm-type EFPI acoustic emission sensor. When the diaphragm is forced to vibrate, the disturbances at different positions of the diaphragm are different, resulting in unequal optical path differences of the reflected light, which causes a phase difference in the reflected light signal, and ultimately causes the interference intensity emission of the reflected light signal to change, and the measured ultrasonic signal is restored through the change in light intensity.

[0013] The test shows that the internal magnetic field distribution of the generator without or with the diaphragm EFPI acoustic emission sensor is basically unchanged. The diaphragm EFPI acoustic emission sensor uses stacked high-magnetic permeability silicon steel sheets to construct the EFPI sensor Fabry-Perot cavity support structure and the selection of the installation position of the generator stator slot EFPI sensor has no effect on the stator magnetic field distribution of large generators, and will not cause the problem of excessive eddy current damage caused by local magnetic field accumulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 and Figure 2 It is a structural schematic diagram of the novel EFPI sensor of the present invention; Figure 3 It is a schematic diagram of the installation position of the novel EFPI sensor of the present invention in the stator slot; Figure 4 for Figure 3 A magnified view of the position A in the middle; Figure 5 The simulation results of the present invention before and after the installation of the new EFPI sensor are shown; In the figure, 1 is a new EFPI sensor, 2 is a high magnetic permeability silicon steel sheet support structure, 3 is a laminated silicon steel sheet, 4 is a diaphragm, 5 is a Fabry-Perot cavity, 6 is an optical fiber line, and 7 is a large motor stator slot. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings of the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0016] In view of the problem that the traditional piezoelectric ceramic partial discharge ultrasonic sensor (PZT) cannot be used under high field strength conditions inside large power equipment due to its own structural characteristics, and the problem that the new extrinsic fiber Fabry-Perot (EFPI) partial discharge acoustic emission sensor cannot avoid the additional impact on the stator magnetic field of large generators, resulting in excessive eddy current damage caused by local magnetic field accumulation, this embodiment provides a new EFPI sensor.

[0017] First, the structural design process of the new EFPI sensor is as follows: like Figure 1 and Figure 2 As shown, the novel EFPI sensor 1 includes a high magnetic permeability silicon steel sheet support structure 2, and the high magnetic permeability silicon steel sheet support structure 2 adopts a stacked silicon steel sheet 3; the EFPI sensor Fabry-Perot cavity support structure 2 is prepared by stacking silicon steel sheets, replacing the original EFPI sensor Fabry-Perot quartz glass support structure; the ferromagnetic properties of the silicon steel sheets used are consistent with the ferromagnetic properties of the silicon steel sheets of the generator stator slots, reducing and detecting the air gap structure, so that the magnetic resistance of the sensor installation position is greatly reduced, ensuring that the original magnetic field line closed channel position changes slightly or does not change.

[0018] A diaphragm 4 is installed on the front end surface of the high magnetic permeability silicon steel sheet support structure 2, and the diaphragm 4 is a quartz diaphragm; the front end surface of the high magnetic permeability silicon steel sheet is recessed inward to form a Fabry-Perot cavity 5; an optical fiber line 6 extending to the Fabry-Perot cavity 5 is installed on the rear side of the high magnetic permeability silicon steel sheet; in terms of structural design, the non-ferromagnetic materials of the new EFPI sensor 1 are only the optical fiber core, the Fabry-Perot cavity 5 and the quartz diaphragm 4, wherein the diameter of the optical fiber core is only 0.25 mm, the thickness of the Fabry-Perot cavity 5 is 0.1 mm, and the core diameter of the optical fiber line 6 is 0.25 mm.

[0019] Second, based on the above-mentioned new EFPI sensor 1, the installation method in the stator slot of a large motor is as follows: When determining the installation position of the new EFPI sensor 1 in the stator slot 7 of a large motor, Figure 3 and Figure 4 As shown, it is necessary to ensure that the Fabry-Perot cavity 5 and the quartz diaphragm 4 structure of the new EFPI sensor 1 are close to the end face of the electrode stator slot; according to the electromagnetic characteristics analysis, the new EFPI sensor 1 has little effect on the magnetic field distribution characteristics of the generator stator slot when in this position. At the same time, the laminated silicon steel sheets 3 constituting the Fabry-Perot cavity support structure of the new EFPI sensor 1 need to be parallel to the laminated silicon steel sheets of the generator stator, so as to facilitate the passage of the electrode stator magnetic flux, form a closed magnetic field line, and the distribution of the magnetic field line changes very little.

[0020] Furthermore, this embodiment also uses simulation software to calculate the distribution of the magnetic field of the generator before and after the new EFPI sensor 1 is installed in the stator slot 7 of the large motor; first, an experimental simulation platform is built to calculate the internal magnetic field distribution characteristics of the generator without and with the EFPI sensor installed; the calculation results are as follows: Figure 5 As shown, Figure 5 Figure a shows that the EFPI sensor is not installed, and Figure b shows that the EFPI sensor is installed. By comparing Figure a and Figure b, it can be seen that the overall magnetic field distribution of the generator has not changed significantly, and the magnetic field distribution in the sensor installation area remains basically unchanged.

[0021] Therefore, it can be considered that the design method of constructing the EFPI sensor Fabry-Perot cavity support structure 2 by stacking high-magnetic permeability silicon steel sheets and the selection of the installation position of the EFPI sensor in the stator slot of the power generation device have no effect on the stator magnetic field distribution of the large generator, and will not lead to the problem of excessive eddy current damage caused by local magnetic field accumulation.

[0022] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A new type of EFPI sensor, Features: This new EFPI sensor is based on the Michelson and Fabry-Perot interference principles. It uses MEMS processing to prepare a sound-sensitive diaphragm with a phase adjustment groove and a pressure balance hole, and combines it with a fiber optic collimator to establish a temperature and pressure adaptive diaphragm-type EFPI acoustic emission sensor. When the diaphragm is forced to vibrate, the disturbances at different positions of the diaphragm are different, resulting in unequal optical path differences of the reflected light, which causes a phase difference in the reflected light signal, and ultimately causes the interference intensity emission of the reflected light signal to change, and the measured ultrasonic signal is restored through the change in light intensity.

2. The novel EFPI sensor according to claim 1, Features: The diaphragm-type EFPI acoustic emission sensor includes a high-magnetic silicon steel sheet support structure, which uses stacked silicon steel sheets. A diaphragm is installed on its front end surface, and the front end surface of the high-magnetic silicon steel sheet is recessed inward to form a Fabry-Perot cavity, and an optical fiber line extending to the Fabry-Perot cavity is installed on its rear side.

3. The novel EFPI sensor according to claim 2, Features: The ferromagnetic properties of the silicon steel sheet are consistent with those of the silicon steel sheet in the stator slot of the generator, thereby reducing and detecting the air gap structure.

4. The novel EFPI sensor according to claim 2, Features: The core diameter of the optical fiber is 0.25 mm.

5. The novel EFPI sensor according to claim 2, Features: The thickness of the Fabry-Perot cavity is 0.1 mm.

6. The novel EFPI sensor according to claim 2, Features: The diaphragm is a quartz diaphragm with a thickness of 0.02 mm.

7. A method for installing a novel EFPI sensor in a stator slot of a large motor, the method being based on the novel EFPI sensor according to any one of claims 1 to 7, Features: When determining the installation position of the diaphragm EFPI acoustic emission sensor in the stator slot of a large motor, the Fabry-Perot cavity and the quartz diaphragm structure of the diaphragm EFPI acoustic emission sensor are close to the end face of the electrode stator slot; at the same time, the laminated silicon steel sheets of the diaphragm EFPI acoustic emission sensor are parallel to the laminated silicon steel sheets of the generator stator.

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