CN105182190A - Transformer partial discharge detection method based on optical fiber external cavity fabry-perot sensors - Google Patents

Abstract

The invention relates to a transformer partial discharge detection method based on optical fiber external cavity fabry-perot sensors in the electrical transformer device partial discharge on-line monitoring technology field. Four optical fiber external cavity fabry-perot sensors are placed in oil in two temperature measuring tanks and two flange tanks at the top of a transformer and integrated with the transformer respectively. The tank structures are employed as ultrasonic signal collectors. An ultrasonic signal generated from transformer partial discharge is transferred to the tanks through transformer oil or the transformer solid structure and transferred to sensing heads through transformer oil in the tanks. The intensity of the signal received at the moment is independent of a position and an angle of a signal source, signals of the sensors are strong, and influences of the oil pressure inside the transformer on the sensors are avoided. The sensors at four positions work at the same time, and the situation is avoided that a signal is block by the internal structure of the transformer. The detection method is advantaged by high sensitivity, high signal collection capability, convenient operation and high anti-interference capability. Transformer partial discharge conditions can be detected well without extra auxiliary structures.

Description

Based on the partial discharge of transformer detection method of fiber external cavity formula F-P sensor

Technical field

The invention belongs to power transformer apparatus local discharge on-line monitoring technique field.In particular to a kind of partial discharge of transformer detection method based on fiber external cavity formula F-P sensor.

Background technology

Partial discharge of transformer on-line monitoring has multiple method both at home and abroad at present, mainly comprise very high frequency(VHF) (VHF) pulse current detection method, ultrahigh frequency (UHF) Electromagnetic Wave Detection method and piezoelectric sensor ultrasonic Detection Method, what wherein VHF and UHF detection method detected is electric signal, is easily subject to the interference of electromagnetic interference signal; What piezoelectric supersonic method detected is ultrasonic signal, and sensor is the ultrasonic signal being attached to the inner shelf depreciation generation of checkout equipment on device housings, although be not vulnerable to the interference of electromagnetic noise, but sensitivity is not high.Also have inside piezoelectric sensor being placed on device housings, in oil, detect shelf depreciation, but due to piezo ultrasound transducers detection sensitivity in oil not high, current potential higher position can not be placed on simultaneously and measure, its detection method is restricted.

The technology of optical method for measuring local discharge of electrical equipment has three kinds---direct detection visible ray method, Faraday magnetooptical effect method and light-supercritical ultrasonics technology.Direct detection visible ray method to be suitable only for transparent dielectric as the high-voltage electrical equipment of insulating material, is not suitable for using solid dielectric, liquid dielectric as the Partial Discharge Detection of the high-voltage electrical equipment of insulating material; Light current sensor based on Faraday magnetooptical effect principle is only suitable for the Partial Discharge Detection of the high-voltage electrical equipment of solid shape, and the high-intensity magnetic field can not got rid of from site space disturbs and cannot distinguish the electromagnetic pulse signal of crosstalk from high-voltage electrical equipment ground wire; Light-supercritical ultrasonics technology sensor has that volume is little, loss is low, it is little to disturb, the advantage of good insulation preformance and anti-explosion, anti-corrosion and being with a wide range of applications.

Light-supercritical ultrasonics technology comprises fiber grating and surveys ultrasonic vibration method and light interference survey ultrasonic vibration method, and fiber optic interferometric method surveys ultrasonic vibration three kinds of methods: fiber optic Michelson (Michelson) interferometric method, optical fiber mach-Ze Deer interfere (Mach-Zehnder) method and Fabry Perot (Fabry-Perot) interferometric method.The sensitivity of Michelson method detection system is not high, and there is the multipath problem of ultrasonic propagation; Not high enough, the complex structure of optical fiber mach-Ze Deer interferometric method frequency, demodulation frequency response is high to equipment requirement; It is simple that Fiber Optic Sensor Fabry-Perot rule has structure, and the advantages such as volume is little, high reliability, high sensitivity, Fast Time Response, and antijamming capability is strong receive the general concern of people.

Optical fiber EFPI (the extrinsicFabry-Perotinterferometer of current studies in China, external cavity type Fabry Perot interferometric sensor), be mainly used in the measurement of the gradual amounts such as temperature, strain, pressure, be still not suitable for high frequency Partial Discharge Detection fast.

Figure 2 shows that fiber external cavity formula F-P sensor result schematic diagram, be made up of optical fiber 01, insulating support 02, silicon sleeve pipe 03 and silicon thin film sheet 04, by carbon dioxide laser hot melt fixing seal between silicon thin film sheet 04 and silicon sleeve pipe 03, by carbon dioxide laser hot melt fixing seal between insulating support 02 and silicon sleeve pipe 03, and insulating support 02 passes through carbon dioxide laser hot melt fixing seal with optical fiber 01, will ensure to align with the center of optical fiber in the center of silicon thin film sheet 04 in the manufacturing process of sensor.

In sensor (EFPI) partial discharge detecting system of compound eye type system in the past, the sensor of compound eye type system is made up of 5 the fiber external cavity formula F-P sensors angularly arranged; The intensity of the signal that sensor receives and the angle between source location and sensor quartz diaphragm vertical direction have much relations, and its detection method is restricted.

Summary of the invention

Object of the present invention proposes the partial discharge of transformer detection method based on fiber external cavity formula F-P sensor, the method utilizes the partial discharge detecting system based on fiber external cavity formula F-P sensor to carry out detecting, and described fiber external cavity formula F-P sensor partial discharge detecting system is by narrow-band light source, optical filter, optical branching device, 4 optical circulators, 4 single-mode fibers, 4 fiber external cavity formula F-P sensors and be made up of 4 photodetectors, 4 amplifiers and oscillograph; Wherein two fiber external cavity formula F-P sensors are placed in transformer top thermometric groove oil, and two other is placed in the flange groove of transformer top both sides; Described narrow-band light source is connected with optical branching device successively with optical filter, optical branching device divide 4 tunnels successively, corresponding to be connected with 4 optical circulators, 4 single-mode fibers and 4 fiber external cavity formula F-P sensors, wherein 4 fiber external cavity formula F-P sensors form fiber external cavity formula F-P sensor arrays; Between optical branching device and 4 optical circulators, 4 optical circulators connect with corresponding 4 photodetectors, 4 amplifiers more respectively successively; Four identical amplifiers are all connected with oscillograph; The method comprises the following steps:

Step 1: placed by two fiber external cavity formula F-P sensors of four identical fiber external cavity formula F-P sensors and be arranged in transformer top thermometric groove oil, two other is placed in the flange groove of transformer top both sides; The optical fiber of four fiber external cavity formula F-P sensors is connected respectively on four passages of partial discharge detecting system, and wherein oscillograph adopts edge from triggering mode, triggering level is transferred on position;

Step 2: power supply, makes each device in running order;

Step 3: the detection signal of observation oscilloscope display, when there being shelf depreciation, fiber external cavity formula F-P sensor has the pulse signal of concussion; If wherein the local discharge signal of certain fiber external cavity formula F-P sensor is obviously more weak, then the path that this sensing station drawn game is put between position exists hinder structure or put a position and sensor distance larger; If wherein the local discharge signal of certain fiber external cavity formula F-P sensor is obviously comparatively strong, then there is not obstruction structure in this sensing station on the path that partial discharge position or sensing station drawn game are put between position; Determine that office puts the existence of phenomenon and puts an approximate region at place, position thus.

Described fiber external cavity formula F-P sensor is arranged in thermometric groove and flange groove oil, not only eliminate inside transformer oil pressure to transducer sensitivity and the impact in serviceable life, trough body structure is equivalent to a ultrasonic signal gatherer simultaneously, the ultrasonic signal that partial discharge of transformer produces propagates on trough body structure by transformer oil or transformer solid structure, trough body structure gatherer is collected signal and is reached fiber external cavity formula F-P sensor by transformer oil in groove, the angle of signal no longer and between source location and sensor quartz diaphragm vertical direction that now fiber external cavity formula F-P sensor is received has relation, and fiber external cavity formula F-P sensor can receive stronger ultrasonic signal, detection sensitivity is put in the office of intensifier.

The invention has the beneficial effects as follows for partial discharge monitoring, high-frequency signal can be measured delicately, there is following features: the fiber external cavity formula F-P sensor for studies in China is mainly used in the measurement of the gradual amounts such as temperature, strain, pressure, still be not suitable for the deficiency of high frequency Partial Discharge Detection fast

1. have highly sensitive, signal collection ability is strong, and easy to operate, the feature that antijamming capability is strong, can suppress the impact that ultrasonic vibration multipath propagation brings.And due to sensor probe little, as a kind of point sensor, can easily be arranged on the detection carrying out shelf depreciation in transformer top thermometric groove and flange groove oil; And when reasonable Arrangement four sensing stations, what energy was rough carries out partial discharge position judgement.

2. fiber external cavity formula F-P sensor is arranged in thermometric groove and flange groove oil, not only eliminate inside transformer oil pressure to transducer sensitivity and the impact in serviceable life, trough body structure is equivalent to a ultrasonic signal gatherer simultaneously, the ultrasonic signal that partial discharge of transformer produces propagates on trough body structure by transformer oil or transformer solid structure, trough body structure gatherer is collected signal and is reached fiber external cavity formula F-P sensor by transformer oil in groove, the angle of signal no longer and between source location and sensor quartz diaphragm vertical direction that now fiber external cavity formula F-P sensor is received has relation, and fiber external cavity formula F-P sensor can receive stronger ultrasonic signal, detection sensitivity is put in the office of intensifier.

Accompanying drawing explanation

Fig. 1 is based on fiber external cavity formula F-P sensor partial discharge of transformer detection system structural representation.

Fig. 2 is the structural representation of existing single fiber external cavity formula enamel amber sensing head.

Fig. 3 is based on fiber external cavity formula F-P sensor partial discharge of transformer detection system mounting arrangements schematic diagram on transformer.

Fig. 4 is the placement schematic diagram of sensing head in transformer thermometric/flange groove.

Fig. 5 is in the maximum interval of light intensity peak peak value, the relation schematic diagram of light intensity and chamber length.

Fig. 6 is light intensity and the long relation schematic diagram of film reflectivity and chamber.

The Partial discharge signal schematic diagram that Fig. 7 is PD meter, optical fiber EFPI sensor and piezoceramic transducer detect.

Fig. 8 is the piezoceramic transducer dough softening, fiber external cavity formula F-P sensor dough softening schematic diagram.Wherein, scheming (a) is piezoceramic transducer dough softening schematic diagram; Figure (b) is fiber external cavity formula F-P sensor dough softening schematic diagram.

When Fig. 9 is unloaded pressurization, the detection signal schematic diagram of PD meter, optical fiber EFPI sensor, piezoelectric ceramics.

Wherein, 1-narrow-band light source, 2-optical filter, 3-optical branching device, 4-optical circulator, 5 single-mode fibers, 6-fiber external cavity formula F-P sensor, 7-photodetector, 8-amplifier, 9-oscillograph, 01-optical fiber, 02-insulating support, 03-silicon sleeve pipe, 04-silicon thin film sheet.

Embodiment

The present invention proposes a kind of partial discharge of transformer detection method based on fiber external cavity formula F-P sensor.Below in conjunction with drawings and Examples, the present invention is described further.

Fig. 1 is based on fiber external cavity formula F-P sensor partial discharge of transformer detection system structural representation.As shown in Figure 1, described fiber external cavity formula F-P sensor partial discharge detecting system is made up of narrow-band light source 1, optical filter 2, optical branching device 3,4 optical circulators 4,4 single-mode fibers 5,4 fiber external cavity formula F-P sensors 6 and 4 photodetectors, 7,4 amplifiers 8 and oscillograph 9; Wherein two fiber external cavity formula F-P sensors 6 are placed in transformer top thermometric groove 12 oil, and two other is placed in flange groove 13 oil of transformer top both sides (as shown in Figure 3,4); Described narrow-band light source 1, optical filter 2 are connected successively with optical branching device 3, optical branching device 3 point of 4 tunnel successively, corresponding being connected with 4 optical circulators, 4,4 single-mode fibers 5 and 4 fiber external cavity formula F-P sensors 6, wherein 4 fiber external cavity formula F-P sensors 6 form fiber external cavity formula F-P sensor array 10; Between optical branching device and 4 optical circulators on tie point, 4 optical circulators 4 connect with corresponding 4 photodetectors 7,4 amplifiers 8 more respectively successively; Four identical amplifiers 8 are all connected with oscillograph 9.

The monochromatic source fixing on 1310nm for wavelength below illustrates, is described as follows the structure of fiber external cavity formula F-P sensor partial discharge of transformer detection system:

1) wavelength fixes on the monochromatic source of 1310nm, obtains monochromatic wavelength light source by narrow-band light source 1 by optical fiber filter filtration.Narrow-band light source 1 selects SLED type light source, and 1310nm fiber band-pass filter selected by wave filter.

2) fiber selection 1310nm single-mode fiber, its center glass core diameter 9um, covering overall diameter 125um.Find at 1310nm wavelength place after tested, the total dispersion of single-mode fiber is zero.From the loss characteristic of optical fiber, 1310nm place is also a low loss window of optical fiber.So select light source of the present invention to select at 1310nm place.

3) PIN photodiode selected by photodetector 7, has the good linearity of incident light quantity and output current; Fast response time; Output error is little; Output variation caused by variation of ambient temperature is little; Make simple; The feature that reliability is high.

4) optical fiber circulator only allows the incident light of certain port non-reciprocal device that reflected light exports from another port from determining port to export.For ensureing that optical fiber is propagated along specified path, optical circulator 4 need be used.

5) amplifier (photoelectricity) 8 of system adopts three grades of amplifications, and wherein every grade of amplifying circuit is consistent, and is together in series.

6) to the explanation (as shown in Figure 2) of the fiber external cavity formula F-P sensor that the present invention adopts

A) design of silicon thin film sheet

Silicon thin film sheet adopts quartz film.The design of silicon thin film sheet comprises the sensitivity of film and the determination of frequency response.The expression formula of the pressure sensitivity of its center is:

${\mathrm{\η}}_{\max }=\frac{Y_{\max }}{P}=\frac{3(1-{\mathrm{\μ}}^2)}{16E{h}^3}{R}^4---\left(1\right)$

The expression formula of minimum natural frequency is:

$f=2.749\×{10}^9\frac{h}{R^2}\left(\mathrm{Hz}\right)---\left(2\right)$

Found by formula, the pressure sensitivity of diaphragm is directly proportional to the biquadratic of its radius, is inversely proportional to the cube of thickness; And its natural frequency is directly proportional to the thickness of diaphragm, with square being inversely proportional to of effective radius.Sensitivity and frequency response are contradictories, therefore take the way of compromising when designing, and make diaphragm reach best sensitivity and Hz-KHz.Selected radius R=0.9mm, thickness h=30, their highest frequency response and sensitivity are f=101.5kHz, loss correction factor η=0.4155.

B) cavity design of fiber external cavity formula F-P sensor

When change of cavity length amplitude is larger, the light intensity that sensor exports will along with chamber long period variation.For the fiber external cavity formula F-P sensor of range of linearity work, its initial work location requires at Q point when incident intensity is I ₀(λ), fiber end face reflectivity is R ₁=0.04, film internal surface reflection rate is R ₂, when the chamber length of fiber external cavity formula enamel amber sensing head is for l, can show that the output optical signal intensity of fiber external cavity formula F-P sensor is according to the theory of optics EFPI interferometer:

$I_r\left(\mathrm{\λ}\right)=\frac{R_1+\mathrm{\η}{R}_2-2\sqrt{{\mathrm{\ηR}}_1{R}_2}\cos \mathrm{\δ}}{1+\mathrm{\η}{R}_1{R}_2-2\sqrt{\mathrm{\η}{R}_1{R}_2}\cos \mathrm{\δ}}{I}_0\left(\mathrm{\λ}\right),---\left(3\right)$

In formula, it is the optical path difference of two bundle reflected light.The intensity of reflected light that characterizes sensor signal quality can be derived and contrast formula is by formula (3):

$V=\frac{2\sqrt{R_1{R}_2}(1+R_1{R}_2-R_1-R_2)}{R_1+R_2+R_1^2{R}_2+R_1{R}_2^2-4R_1{R}_2},---\left(4\right)$

Loss correction factor η is:

$\mathrm{\η}={\mathrm{\η}}_1\×{\mathrm{\η}}_2\×{\mathrm{\η}}_3=0.9493{\mathrm{\η}}_1=0.9493{\left\{\frac{1}{1+{[2\mathrm{l\λ}/2\mathrm{\π}{n}_0{\mathrm{\ω}}^2]}^2}\right\}}^2---\left(5\right)$

By light source center wavelength 1310nm, n ₀=1.455 and ω=3.8 μm substitute into formula (5).Carry out simulation result as shown in Figure 5 to interference light intensity, Fig. 5 is light intensity and the long relation schematic diagram of film reflectivity and chamber.The reflectivity of film is when 0.35 ~ 0.36 is interval, and the peak-to-peak value of light intensity change is maximum, and it is very favorable for choosing quiescent point for us like this.

The relation of light intensity when being between 0.348 ~ 0.362 film reflectivity and chamber length emulates, and obtains result as shown in Figure 6.Fig. 6 is in the maximum interval of light intensity peak peak value, the relation schematic diagram of light intensity and chamber length.According to analysis, when determining that chamber length is 50.58 μm, light intensity mediates, namely suitable quiescent point Q.

Detection method for local discharge based on fiber external cavity formula F-P sensor partial discharge of transformer detection system is: the method utilizes the partial discharge detecting system based on fiber external cavity formula F-P sensor to carry out detecting, and comprises the following steps:

Step 1, placed by two fiber external cavity formula F-P sensors of four identical fiber external cavity formula F-P sensors and be arranged in transformer top thermometric groove oil, two other is placed in the flange groove of transformer top both sides; The optical fiber of four fiber external cavity formula F-P sensors is connected respectively on four passages of partial discharge detecting system, and wherein oscillograph adopts edge from triggering mode, triggering level is transferred on position;

Step 2: power supply, makes each device in running order;

Step 3: the detection signal of observation oscilloscope display, when there being shelf depreciation, fiber external cavity formula F-P sensor has the pulse signal of concussion; If wherein the local discharge signal of certain fiber external cavity formula F-P sensor is obviously more weak, then the path that this fiber external cavity formula F-P sensor position drawn game is put between position exists and hinders structure or put a position with fiber external cavity formula F-P sensor apart from larger; If wherein the local discharge signal of certain fiber external cavity formula F-P sensor is obviously comparatively strong, then there is not obstruction structure in this fiber external cavity formula F-P sensor position on the path that partial discharge position or the position drawn game of fiber external cavity formula F-P sensor are put between position; Determine that office puts the existence of phenomenon and puts an approximate region at place, position thus.

[performance verification experiment]:

The performance of fiber external cavity formula F-P sensor of the present invention can be tested by the external cavity type of single-path optical fiber shown in Fig. 1 F-P sensor detection system.Paper oil insulation defect partial discharge model is set in laboratory, also measure local discharge signal while of by pulse current method PD meter detection system, piezoceramic transducer system and single-path optical fiber external cavity type F-P sensor detection system respectively, the sensing head of visible the present invention's design can detect local discharge signal well.

The Partial discharge signal schematic diagram that Fig. 7 is PD meter, fiber external cavity formula F-P sensor and piezoceramic transducer detect, by the high-field electrode of partial discharge model---pin electrode takes off, other conditions are constant, unloaded pressurization, be forced into 17kV, the signal detected as Fig. 8 zero load pressurization time, shown in the detection signal schematic diagram of PD meter, fiber external cavity formula F-P sensor, piezoelectric ceramics.Pass through Fig. 8, can obtain, after zero load is pressurized to 17kV, electromagnetic interference (EMI) is there is or testing transformer produces transaudient electromagnetic interference signal in environment, PD meter detects discharge signal, and optical fiber ultrasonic sensor is corresponding with it without ultrasonic signal with piezoceramic transducer, this also illustrates ultrasonic sensor and there is good anti-electromagnetic interference capability, and fiber external cavity formula F-P sensor is compared piezoceramic transducer and had better antijamming capability.

Fig. 8 is the signal attenuation curve synoptic diagram that sensor detects, wherein, (a) is piezoceramic transducer degree schematic diagram; B () is fiber external cavity formula F-P sensor dough softening schematic diagram.Fiber external cavity formula F-P sensor ultrasound wave response amplitude under the ultrasound wave response amplitude of the fiber external cavity formula F-P sensor under the different distance obtained and 15cm is asked ratio, then add up each to average apart from lower 50 groups of data, same method processes the signal that piezoceramic transducer detects, can obtain dough softening curve as (a) piezoceramic transducer dough softening schematic diagram in Fig. 8; , shown in (b) fiber external cavity formula F-P sensor dough softening schematic diagram.Can see that the decay of piezoelectric ceramics dough softening opposed optical fibers external cavity type F-P sensor is very fast, substantially, local discharge signal is can't detect at 30cm place, and the distance that fiber external cavity formula F-P sensor puts source 75cm in distance office still can detect larger discharge signal, this proves that the sensitivity of fiber external cavity formula F-P sensor is higher, faint local discharge signal can be detected.

The present invention proposes fiber external cavity formula F-P sensor partial discharge detecting system to be placed on the method realizing partial discharge of transformer on-line monitoring in transformer top thermometric groove and flange groove first, and roughly can carry out partial discharge position estimation.The present invention has highly sensitive, and signal collection ability is strong, and simple to operate, the feature that antijamming capability is strong, can suppress the impact that ultrasonic vibration multipath propagation brings.Fiber external cavity formula F-P sensor is arranged in thermometric groove and flange groove oil, not only eliminate inside transformer oil pressure to transducer sensitivity and the impact in serviceable life, trough body structure is equivalent to a ultrasonic signal gatherer simultaneously, the ultrasonic signal that partial discharge of transformer produces propagates on trough body structure by transformer oil or transformer solid structure, trough body structure gatherer is collected signal and is reached fiber external cavity formula F-P sensor by transformer oil in groove, the angle of signal no longer and between source location and sensor quartz diaphragm vertical direction that now fiber external cavity formula F-P sensor is received has relation, and fiber external cavity formula F-P sensor can receive stronger ultrasonic signal, detection sensitivity is put in the office of intensifier, the present invention can measure high-frequency signal delicately, for partial discharge monitoring.

Claims (6)

1., based on a partial discharge of transformer detection method for fiber external cavity formula F-P sensor, the method utilizes the partial discharge detecting system based on fiber external cavity formula F-P sensor to carry out detecting; Described fiber external cavity formula F-P sensor partial discharge detecting system is by narrow-band light source, optical filter, optical branching device, 4 optical circulators, 4 single-mode fibers, 4 fiber external cavity formula F-P sensors and be made up of 4 photodetectors, 4 amplifiers and oscillograph; Wherein two fiber external cavity formula F-P sensors are placed in transformer top thermometric groove oil, and two other is placed in the flange groove of transformer top both sides; Described narrow-band light source is connected with optical branching device successively with optical filter, optical branching device divide 4 tunnels successively, corresponding to be connected with 4 optical circulators, 4 single-mode fibers and 4 fiber external cavity formula F-P sensors, wherein 4 fiber external cavity formula F-P sensors form fiber external cavity formula F-P sensor arrays; Between optical branching device and 4 optical circulators, 4 optical circulators connect with corresponding 4 photodetectors, 4 amplifiers more respectively successively; Four identical amplifiers are all connected with oscillograph; The method comprises the following steps:

Step 1: placed by two fiber external cavity formula F-P sensors of four identical fiber external cavity formula F-P sensors and be arranged in transformer top thermometric groove oil, two other is placed in the flange groove of transformer top both sides; The optical fiber of four fiber external cavity formula F-P sensors is connected respectively on four passages of partial discharge detecting system, and wherein oscillograph adopts edge from triggering mode, triggering level is transferred on position;

Step 2: power supply, makes each device in running order;

Step 3: the detection signal of observation oscilloscope display, when there being shelf depreciation, fiber external cavity formula F-P sensor has the pulse signal of concussion; If wherein the local discharge signal of certain fiber external cavity formula enamel amber sensing head is obviously more weak, then the path that this fiber external cavity formula F-P sensor position drawn game is put between position exists and hinders structure or put a position with fiber external cavity formula enamel amber sensing head apart from larger; If wherein the local discharge signal of certain fiber external cavity formula F-P sensor is obviously stronger, then there is not obstruction structure in this fiber external cavity formula F-P sensor position on the path that partial discharge position or the position drawn game of fiber external cavity formula F-P sensor are put between position, determines that office puts the existence of phenomenon and puts an approximate region at place, position thus.

2. a kind of partial discharge of transformer detection method based on fiber external cavity formula F-P sensor according to claim 1, it is characterized in that, described fiber external cavity formula F-P sensor is arranged in thermometric groove and flange groove oil, not only eliminate inside transformer oil pressure to transducer sensitivity and the impact in serviceable life, trough body structure is equivalent to a ultrasonic signal gatherer simultaneously, the ultrasonic signal that partial discharge of transformer produces propagates on trough body structure by transformer oil or transformer solid structure, trough body structure gatherer is collected signal and is reached fiber external cavity formula F-P sensor by transformer oil in groove, the angle of signal no longer and between source location and sensor quartz diaphragm vertical direction that now fiber external cavity formula F-P sensor is received has relation, and fiber external cavity formula F-P sensor can receive stronger ultrasonic signal, detection sensitivity is put in the office of intensifier.

3. a kind of partial discharge of transformer detection method based on fiber external cavity formula F-P sensor according to claim 1, is characterized in that, described narrow-band light source is SLED type wavelength is the monochromatic source of 1310nm.

4. a kind of partial discharge of transformer detection method based on fiber external cavity formula F-P sensor according to claim 1, it is characterized in that, described optical filter is 1310nm fiber band-pass filter.

5. a kind of partial discharge of transformer detection method based on fiber external cavity formula F-P sensor according to claim 4, it is characterized in that, described single-mode fiber is 1310nm single-mode fiber, its center glass core diameter 9um, covering overall diameter 125um.

6. a kind of partial discharge of transformer detection method based on fiber external cavity formula F-P sensor according to claim 1, it is characterized in that, described photodetector is PIN photodiode.