CN116381489B - Method for detecting three-dimensional air gap eccentric faults of non-invasive high-capacity generator - Google Patents
Method for detecting three-dimensional air gap eccentric faults of non-invasive high-capacity generator Download PDFInfo
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- CN116381489B CN116381489B CN202310426462.9A CN202310426462A CN116381489B CN 116381489 B CN116381489 B CN 116381489B CN 202310426462 A CN202310426462 A CN 202310426462A CN 116381489 B CN116381489 B CN 116381489B
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- 238000005259 measurement Methods 0.000 claims description 5
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
- G01R31/343—Testing dynamo-electric machines in operation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
- G01B7/18—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge using change in resistance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/30—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring angles or tapers; for testing the alignment of axes
- G01B7/31—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes
- G01B7/312—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes for measuring eccentricity, i.e. lateral shift between two parallel axes
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Abstract
The application provides a method for detecting three-dimensional air gap eccentric faults of a non-invasive high-capacity generator, which comprises the following steps: strain data at measuring points at two axial ends of four generator stator windings distributed along the circumference are collected through resistance strain gauges; collecting a plurality of groups of strain data by using a collecting instrument and respectively calculating effective values of the strain data; calculating to obtain average values of different measuring points according to the effective values of a plurality of groups of strain data; and determining the type of the static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points. The application solves the problems that the fault type of the air gap eccentricity of the generator and the corresponding direction and degree of the fault type cannot be accurately detected in the prior art.
Description
Technical Field
The application relates to the technical field of power generation, in particular to a method for detecting three-dimensional air gap eccentric faults of a non-invasive high-capacity generator.
Background
Most generators operate in sub-health conditions, wherein different degrees of air gap eccentricity are one of the most common faults of the generator, and insufficient rigidity of a rotor, abrasion of a bearing, bending caused by heating and the like can cause the air gap eccentricity of the generator. The generator air gap eccentricity can be divided into radial eccentricity and axial eccentricity, wherein the radial eccentricity indicates that the center of a generator stator is not coincident with the center of a rotor in the radial direction, and the axial eccentricity indicates that the rotor of the generator moves axially relative to the stator.
The slight eccentric fault does not obviously affect the operation of the generator, but the gradual deepening of the fault degree can seriously distort the air-gap field of the generator, so that the performance index of the generator is reduced, the bending abrasion of a rotor, the insulation breakdown of a winding and even the generator is burnt out when the performance index of the generator is seriously reduced, and serious economic loss and personal safety are caused.
Disclosure of Invention
In order to overcome the defects of the prior art, the application aims to provide a detection method for the three-dimensional air gap eccentricity fault of a non-invasive high-capacity generator.
In order to achieve the above object, the present application provides the following solutions:
a method for detecting three-dimensional air gap eccentric faults of a non-invasive high-capacity generator comprises the following steps:
strain data at measuring points at two axial ends of four generator stator windings distributed along the circumference are collected through resistance strain gauges;
collecting a plurality of groups of strain data by using a collecting instrument and respectively calculating effective values of the strain data;
calculating to obtain average values of different measuring points according to the effective values of a plurality of groups of strain data;
and determining the type of the static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points.
Preferably, the collecting strain data at measuring points at two axial ends of four generator stator windings distributed along the circumference through the resistance strain gauge includes:
the method comprises the steps that 4 corresponding strain gauges are evenly arranged at the two axial ends of each generator stator winding along the inner circumferential direction of the generator stator winding;
strain data were measured for 8 pairs of strain gages corresponding to 8 measurement points.
Preferably, measuring strain data of 8 measuring points corresponding to the 8 pairs of strain gages includes:
forming an electric bridge by using the fixed resistor and the strain gauge;
acquiring an electric signal corresponding to the measuring point by using the electric bridge;
and obtaining strain data corresponding to the measuring points through the electric signals.
Preferably, before the collecting a plurality of sets of the strain data by using the collecting instrument, the method further comprises:
and balancing and resetting the measuring channel of the acquisition instrument.
Preferably, the calculation formula of the effective value is:
wherein DeltaT is the time interval of two adjacent samplings epsilon n Is the strain value in the N-1 sampling time, N is the sampling point number, T is the sampling period, epsilon rms Is the effective value of one sampling period.
Preferably, the calculation formula of the average value is:
wherein M is the number of groups of measurement data corresponding to each measurement point, epsilon a Is the average value of strain at one measuring point.
Preferably, determining the type of the static eccentric fault and the direction and degree corresponding to the type of the static eccentric fault according to the average value of the different measuring points includes:
if the average value of the strain of the 8 measuring points is equal to the strain under the normal condition, the generator runs normally without static eccentric faults;
if the average value of the strains of the 2 measuring points which are axially opposite in the 4 groups is equal to each other but the average value of the strains of the circumferential measuring points is unequal, determining the type of the static eccentric fault as that the generator generates radial eccentricity of an air gap;
if the average values of the strains of the 4 measuring points in the circumferential direction at the two ends are respectively equal but the average values of the strains of the 2 measuring points which are opposite in the axial direction are unequal, determining the type of the static eccentric fault as that the generator generates air gap axial eccentricity;
and if the average value of the strains of the 4 measuring points in the circumferential direction at the two ends is not equal and the average value of the strains of the 2 measuring points opposite in the axial direction is not equal, determining the type of the static eccentric fault as that the generator generates air gap mixing eccentricity.
Preferably, determining the type of the static eccentric fault and the direction and degree corresponding to the type of the static eccentric fault according to the average value of the different measuring points includes:
if the average value of the strain of 8 measuring points is unequal, the average value of the strain of 2 sets of opposite measuring points in the axial direction is equal, and the average value of the other 2 sets of measuring points is respectively a maximum strain set and a minimum strain set, determining the radial eccentric direction of the air gap of the generator as the radial eccentric direction of the air gap biased to the measuring point with large strain;
if the average value of the strains of 8 measuring points is unequal, the average value of the strains of 2 sets of opposite measuring points in the axial direction is equal, the average value of the strains of 2 sets of measuring points is larger than that of the other 2 sets, and if the average value of the strains of 2 sets of large strains is equal, the average value of the strains of 2 sets of small strains is equal, the radial eccentric direction of the air gap of the generator is determined to be the radial eccentric direction of the air gap which is deviated to the middle between the two sets of large strain measuring points;
if the average value of the strains of 8 measuring points is unequal, the average value of the strains of 2 groups of opposite measuring points in the axial direction is equal, the average value of the strains of 2 groups of measuring points is larger than that of the other 2 groups, if the average value of the strains of 2 groups of large strains is unequal, the radial eccentric direction of the air gap of the generator is determined to be eccentric to the radial eccentric direction of the air gap between the two groups of large strain measuring points, and the center of the stator of the generator is close to the measuring point of the maximum strain group;
if the average value of the strain of 8 measuring points is not equal, the larger the difference between the average value of the maximum strain group and the average value of the minimum strain group is, the larger the air gap eccentricity is.
Preferably, determining the type of the static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points, and further includes:
if the average value of the strain of 8 measuring points is unequal, and the average value of the strain of 4 measuring points in the circumferential direction at the two axial ends is respectively equal but the average value of the strain of 2 measuring points opposite to each other in the axial direction is unequal, determining that the axial eccentric direction of the air gap is eccentric in the axial direction of the air gap at one end of the measuring point with large strain;
if the strain average values of the 8 measuring points are not equal, the larger the difference value between the large strain end and the small strain end is, the larger the air gap eccentricity is.
According to the specific embodiment provided by the application, the application discloses the following technical effects:
the application provides a method for detecting three-dimensional air gap eccentric faults of a non-invasive high-capacity generator.
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In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for detecting a three-dimensional air gap eccentricity fault of a non-invasive high-capacity generator according to an embodiment of the present application;
fig. 2 is a schematic diagram of strain gauge distribution according to an embodiment of the present application;
fig. 3 is a schematic view of a winding structure according to an embodiment of the present application;
FIG. 4 is a schematic diagram of circuit connection according to an embodiment of the present application;
fig. 5 is a schematic illustration of the type of eccentricity provided by an embodiment of the present application.
Reference numerals:
1-strain gage, 2-end of winding, 3-straight line segment of winding.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The application aims to provide a method for detecting three-dimensional air gap eccentricity faults of a non-invasive high-capacity generator. The method solves the problem that the air gap eccentricity of the generator cannot be accurately detected in the prior art at early stage and the direction and degree corresponding to the fault type.
In order that the above-recited objects, features and advantages of the present application will become more readily apparent, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description.
As shown in FIG. 1, the application provides a method for detecting three-dimensional air gap eccentricity faults of a non-invasive high-capacity generator, which comprises the following steps:
step 100: strain data at measuring points at two axial ends of four generator stator windings distributed along the circumference are collected through the resistance strain gauge 1;
step 200: collecting a plurality of groups of strain data by using a collecting instrument and respectively calculating effective values of the strain data;
step 300: calculating to obtain average values of different measuring points according to the effective values of a plurality of groups of strain data;
step 400: and determining the type of the static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points.
Further, the strain data at the measuring points at the two axial ends of the four generator stator windings distributed along the circumference are collected through the strain gauge 1, and the method comprises the following steps:
the method comprises the steps of evenly arranging 4 corresponding strain gauges 1 along the inner circumferential direction of the stator windings of each generator at the two axial ends of the stator windings of each generator;
strain data corresponding to 8 measuring points of 8 pairs of strain gages 1 are measured.
Specifically, the strain gauges 1 are arranged at the junction of the straight line section 3 of the corresponding winding and the end part 2 of the winding, and the 2 strain gauges 1 are arranged on the winding by using an orthogonal configuration method and form a half-bridge rectifying circuit with two fixed resistors, so that the strain gauges 1 are a pair. The distribution of the strain gauges 1 is shown in fig. 2, the specific arrangement positions and winding structures of the strain gauges 1 are shown in fig. 3, and the circuit is shown in fig. 4.
Further, measuring strain data of 8 measuring points corresponding to the 8 pairs of strain gauges 1 comprises:
forming an electric bridge with the strain gauge 1 by using a fixed resistor;
acquiring an electric signal corresponding to the measuring point by using the electric bridge;
and obtaining strain data corresponding to the measuring points through the electric signals.
Specifically, the strain gauge 1 comprises 2 strain gauges 1, each strain gauge 1 extends to form two wires, each group of strain gauges 1 and two fixed resistors form an electric bridge, the direct current power supply supplies power, the strain of the winding is measured through the change of an electric signal, and the strain of the winding is judged through four measuring points.
The concrete connection is as follows: one wire of the strain gage Rg1 is connected with the +Eg end, the other wire is connected with one wire of the strain gage Rg2 and is connected with the Vi+ end, and the other wire of the strain gage Rg2 is connected with the-Eg end. Where Vi is the output voltage and Eg is the bridge voltage. The output voltage signal Vi is converted into a strain signal through the acquisition instrument and is transmitted into a computer, data comparison analysis is carried out in the computer, and the eccentric direction and degree of the generator are judged.
The data comparison mode is as follows: and measuring a plurality of groups of winding strain curves to obtain effective values (root mean square values), respectively calculating the average value of the strain effective values of 8 measuring points, comparing the strain sizes, and judging the eccentric direction and degree.
Specifically, before the plurality of groups of strain data are collected by the collecting instrument, the method further comprises:
and balancing and resetting the measuring channel of the acquisition instrument.
The embodiment also discloses a specific principle:
the air gap magnetic potential of the generator is as follows when the generator operates normally and eccentrically:
f(α m ,t)＝F δ cos(ωt-pα m +β)；
where p is the pole pair number, the parameter ω=2pi F is the angular frequency, F δ Is the composite magnetic potential amplitude of stator and rotor, alpha m Is the mechanical angle (starting from the minimum point of the air gap) that is used to describe the detailed circumferential position of the air gap.
The air gap flux guide of the generator is as follows when the generator operates normally and eccentrically:
mu in the middle 0 Vacuum permeability g 0 Is the average value of the length of the air gap, delta s Is the rotor static eccentricity. Λ type 0 Is the air gap flux guide under normal condition, is a constant, but the air gap flux guide lambda is a constant and alpha in static and eccentric faults m Related variable values.
The air gap flux density calculation formula of the generator is as follows:
B a (α m ,t)＝f(α m ,t)Λ(α m )；
B a is the air gap flux density of the straight line area.
In order to make the measured data more obvious, it is preferable that the present patent measures the winding strain at the junction of the straight section 3 of the winding and the end 2 of the winding, the end magnetic density B when the generator is running according to the mirroring method and Biot-Savart law end The method comprises the following steps:
wherein B is end Is the air gap flux density of the end region, i k dl is the base current vector and r is i k distance dl to the calculation point, L k Is the central track of the end winding, N is the calculated point number。η，η 2 And eta 1 Is a coefficient representing more than 0 and less than 1, and the specific relation is as follows: 0<η 1 <η<η 2 <1。
Specifically, the end magnetic field (end) is smaller than the main magnetic field (straight line segment), so the end magnetic density is multiplied by a coefficient eta of more than 0 and less than 1 relative to the straight line segment magnetic density, the protruding end magnetic density is increased after the axial eccentricity of the air gap occurs, the coefficient eta is increased to eta 2, the evacuating end magnetic density is reduced, and the coefficient eta is reduced to eta 1 The radial electromagnetic force born by the winding is the largest, so the patent measures the radial strain of the winding, and the radial electromagnetic force born by the end winding is as follows according to ampere force law and electromagnetic induction law:
where v is the magnetic field linear velocity of the cut winding, Z 1 Is the reactance of the winding, L and L are the axial lengths of the winding wire portion and end, respectively.
The strain of the generator winding after being stressed is as follows:
e is the modulus of elasticity of the winding and is a constant.
Because the positions of the measuring points are the same relative to the center distance of the generator and the positions of the measuring points are the same relative to the normal positions of the winding, the electromagnetic force born by the winding is the same during operation, and therefore the effective values of the strain of the winding measured during normal operation are consistent.
After the eccentric fault occurs, the strain effective values of all the measuring points are not the same, and the eccentric direction and degree can be judged according to the strain data of the four measured points.
The winding component is a straight line segment and an end part, the straight line segment is fixed in a stator slot, and the end part is suspended, so that the end part of the winding is poor in rigidity and easy to deform, wherein the stress strain at the junction of the straight line segment and the end part of the winding is maximum, and the junction of the straight line segment 3 of the winding and the end part 2 of the winding is preferentially selected as the measured strain point.
The effective value calculation formula is:
delta T is the time interval between two adjacent samplings epsilon n Is the value of strain in the N-1 sampling time (replaced by the N strain value), N is the sampling point number, T is the sampling period (time), epsilon rms Is the effective value of one sampling period.
The strain was measured at the same time at each station, at least 10 sets of data were measured (10 cycles), the average of the strain effective values at each station was calculated, and 8 data were compared.
The average value calculation formula is:
m is the number of sets of measured data for each point ε a Is the average value of strain at one measuring point.
Specifically, determining the type of the static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points comprises the following steps:
if the average value of the strain of the 8 measuring points is equal to the strain under the normal condition, the generator runs normally without static eccentric faults;
if the average value of the strains of the 2 measuring points which are axially opposite in the 4 groups is equal to each other but the average value of the strains of the circumferential measuring points is unequal, determining the type of the static eccentric fault as that the generator generates radial eccentricity of an air gap;
if the average values of the strains of the 4 measuring points in the circumferential direction at the two ends are respectively equal but the average values of the strains of the 2 measuring points which are opposite in the axial direction are unequal, determining the type of the static eccentric fault as that the generator generates air gap axial eccentricity;
and if the average value of the strains of the 4 measuring points in the circumferential direction at the two ends is not equal and the average value of the strains of the 2 measuring points opposite in the axial direction is not equal, determining the type of the static eccentric fault as that the generator generates air gap mixing eccentricity. The eccentric type is schematically shown in fig. 5.
Specifically, determining the type of the static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points comprises the following steps:
the average value of the strain of the 8 measuring points is equal to the strain under normal conditions, so that the generator operates normally; the strain value under the normal condition in the application is a fixed value, and the normal running state of the generator can be evaluated and referenced.
If the average value of the strain of 8 measuring points is unequal, the average value of the strain of 2 sets of opposite measuring points in the axial direction is equal, and the average value of the other 2 sets of measuring points is respectively a maximum strain set and a minimum strain set, determining the radial eccentric direction of the air gap of the generator as the radial eccentric direction of the air gap biased to the measuring point with large strain;
if the average value of the strains of 8 measuring points is unequal, the average value of the strains of 2 sets of opposite measuring points in the axial direction is equal, the average value of the strains of 2 sets of measuring points is larger than that of the other 2 sets, and if the average value of the strains of 2 sets of large strains is equal, the average value of the strains of 2 sets of small strains is equal, the radial eccentric direction of the air gap of the generator is determined to be the radial eccentric direction of the air gap which is deviated to the middle between the two sets of large strain measuring points;
if the average value of the strains of 8 measuring points is unequal, the average value of the strains of 2 groups of opposite measuring points in the axial direction is equal, the average value of the strains of 2 groups of measuring points is larger than that of the other 2 groups, if the average value of the strains of 2 groups of large strains is unequal, the radial eccentric direction of the air gap of the generator is determined to be eccentric to the radial eccentric direction of the air gap between the two groups of large strain measuring points, and the center of the stator of the generator is close to the measuring point of the maximum strain group;
if the average value of the strain of 8 measuring points is not equal, the larger the difference between the average value of the maximum strain group and the average value of the minimum strain group is, the larger the air gap eccentricity is.
Specifically, determining the type of the static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points, and further comprising:
the strain of the 8 measuring points is equal to the strain under normal conditions, so that the generator operates normally;
if the average value of the strain of 8 measuring points is unequal, and the average value of the strain of 4 measuring points in the circumferential direction at the two axial ends is respectively equal but the average value of the strain of 2 measuring points opposite to each other in the axial direction is unequal, determining that the axial eccentric direction of the air gap is eccentric in the axial direction of the air gap at one end of the measuring point with large strain;
if the strain average values of the 8 measuring points are not equal, the larger the difference value between the large strain end and the small strain end is, the larger the air gap eccentricity is.
Specifically, the method for judging the air gap mixing eccentric direction of the generator comprises the following steps:
case 1: the strain of the 8 measuring points is equal to the strain under normal conditions, so that the generator operates normally;
case 2: and if the strains of the 8 measuring points are unequal, the strains of the two measuring points in each group are unequal, and the strains of the 4 groups of measuring points are unequal, judging the radial eccentric direction by referring to the air gap radial eccentric direction judging mode, and judging the axial eccentric direction by referring to the air gap axial eccentric direction judging mode.
The judgment mode of the air gap mixing eccentricity degree of the generator is as follows:
case 1: the strain of the 8 measuring points is equal to the strain under normal conditions, so that the generator operates normally;
case 2: and if the strain of the 8 measuring points is unequal, judging the radial eccentricity by referring to an air gap radial eccentricity judging mode, and judging the axial eccentricity by referring to an air gap axial eccentricity judging mode.
The beneficial effects of the application are as follows:
the application aims to provide a method for detecting three-dimensional air gap eccentricity faults of a non-invasive high-capacity generator. The problem that the fault type of the air gap eccentricity of the generator and the direction and degree corresponding to the fault type cannot be accurately detected in the early stage in the prior art is solved.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present application have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present application and the core ideas thereof; also, it is within the scope of the present application to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the application.
Claims (6)
1. The method for detecting the three-dimensional air gap eccentric fault of the non-invasive high-capacity generator is characterized by comprising the following steps of:
strain data at measuring points at two axial ends of four generator stator windings distributed along the circumference are collected through resistance strain gauges;
collecting a plurality of groups of strain data by using a collecting instrument and respectively calculating effective values of the strain data;
calculating to obtain average values of different measuring points according to the effective values of a plurality of groups of strain data;
determining the type of static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points;
strain data at measuring points at two axial ends of four generator stator windings distributed along the circumference are collected through resistance strain gages, and the method comprises the following steps:
the method comprises the steps that 4 corresponding strain gauges are evenly arranged at the two axial ends of any one generator stator winding along the inner side circumferential direction of the generator stator winding;
measuring strain data of 8 pairs of strain gauges corresponding to 8 measuring points;
determining the type of the static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points, wherein the method comprises the following steps:
if the average value of the strain of the 8 measuring points is equal to the strain under the normal condition, the generator runs normally without static eccentric faults;
if the average value of the strains of the 2 measuring points which are axially opposite in the 4 groups is equal to each other but the average value of the strains of the circumferential measuring points is unequal, determining the type of the static eccentric fault as that the generator generates radial eccentricity of an air gap;
if the average values of the strains of the 4 measuring points in the circumferential direction at the two ends are respectively equal but the average values of the strains of the 2 measuring points which are opposite in the axial direction are unequal, determining the type of the static eccentric fault as that the generator generates air gap axial eccentricity;
if the average value of the strains of the 4 measuring points in the circumferential direction at the two ends is unequal and the average value of the strains of the 2 measuring points opposite in the axial direction is unequal, determining the type of the static eccentric fault as that the generator generates air gap mixing eccentricity;
determining the type of the static and eccentric faults and the direction and degree corresponding to the type of the static and eccentric faults according to the average value of the different measuring points, wherein the method comprises the following steps:
if the average value of the strain of 8 measuring points is unequal, the average value of the strain of 2 sets of opposite measuring points in the axial direction is equal, and the average value of the other 2 sets of measuring points is respectively a maximum strain set and a minimum strain set, determining the radial eccentric direction of the air gap of the generator as the radial eccentric direction of the air gap biased to the measuring point with large strain;
if the average value of the strains of 8 measuring points is unequal, the average value of the strains of 2 sets of opposite measuring points in the axial direction is equal, the average value of the strains of 2 sets of measuring points is larger than that of the other 2 sets, and if the average value of the strains of 2 sets of large strains is equal, the average value of the strains of 2 sets of small strains is equal, the radial eccentric direction of the air gap of the generator is determined to be the radial eccentric direction of the air gap which is deviated to the middle between the two sets of large strain measuring points;
if the average value of the strains of 8 measuring points is unequal, the average value of the strains of 2 groups of opposite measuring points in the axial direction is equal, the average value of the strains of 2 groups of measuring points is larger than that of the other 2 groups, if the average value of the strains of 2 groups of large strains is unequal, the radial eccentric direction of the air gap of the generator is determined to be eccentric to the radial eccentric direction of the air gap between the two groups of large strain measuring points, and the center of the stator of the generator is close to the measuring point of the maximum strain group;
if the average value of the strain of 8 measuring points is not equal, the larger the difference between the average value of the maximum strain group and the average value of the minimum strain group is, the larger the air gap eccentricity is.
2. The method for detecting a three-dimensional air gap eccentricity fault of a non-invasive high-capacity generator according to claim 1, wherein measuring strain data of 8 measuring points corresponding to the 8 pairs of strain gages comprises:
forming an electric bridge by using the fixed resistor and the strain gauge;
acquiring an electric signal corresponding to the measuring point by using the electric bridge;
and obtaining strain data corresponding to the measuring points through the electric signals.
3. The method for detecting a three-dimensional air gap eccentricity fault of a non-invasive high-capacity generator according to claim 2, further comprising, prior to said collecting a plurality of sets of said strain data with the collector:
and balancing and resetting the measuring channel of the acquisition instrument.
4. The method for detecting a three-dimensional air gap eccentricity fault of a non-invasive high-capacity generator according to claim 1, wherein the effective value is calculated according to the formula:
wherein DeltaT is the time interval of two adjacent samplings epsilon n Is the strain value in the N-1 sampling time, N is the sampling point number, T is the sampling period, epsilon rms Is the effective value of one sampling period.
5. The method for detecting a three-dimensional air gap eccentricity fault of a non-invasive high-capacity generator according to claim 1, wherein the calculation formula of the average value is:
wherein M is the number of groups of measurement data corresponding to each measurement point, epsilon a Is the average of strain of one measuring pointValues.
6. The method for detecting a three-dimensional air gap eccentricity fault of a non-invasive high-capacity generator according to claim 1, wherein determining the type of the static eccentricity fault and the direction and degree corresponding to the type of the static eccentricity fault according to the average value of the different measuring points, further comprises:
if the average value of the strain of 8 measuring points is unequal, and the average value of the strain of 4 measuring points in the circumferential direction at the two axial ends is respectively equal but the average value of the strain of 2 measuring points opposite to each other in the axial direction is unequal, determining that the axial eccentric direction of the air gap is eccentric in the axial direction of the air gap at one end of the measuring point with large strain;
if the strain average values of the 8 measuring points are not equal, the larger the difference value between the large strain end and the small strain end is, the larger the air gap eccentricity is.
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