Outer rotor permanent magnet generator stator turn-to-turn short circuit fault identification method

Abstract

The invention discloses an outer rotor permanent magnet generator stator turn-to-turn short circuit fault identification method, and belongs to the technical field of generator fault identification, and the method comprises the following steps: S1, measuring an outer rotor permanent magnet generator torque signal through a detection unit; and S2, performing signal processing on the torque signal to determine a turn-to-turn short circuit fault of the outer rotor permanent magnet generator. The outer rotor permanent magnet generator stator turn-to-turn short circuit fault identification method is simple in operation and high in identification precision, and the generator stator turn-to-turn short circuit fault identification efficiency and identification precision are improved.

Description

Technical Field

[0001] The invention relates to the technical field of generator fault identification, and in particular to a method for identifying stator turn-to-turn short-circuit faults of an outer rotor permanent magnet generator. Background Art

[0002] As one of the common fault types of motors, the timeliness and accuracy of the diagnosis of stator turn-to-turn short circuit faults directly affect the reliability of the generator system and the operating efficiency of the entire production line. Data shows that 30% of generator faults are caused by stator winding turn-to-turn short circuit faults, which refers to the insulation damage between different turns of the same phase in the stator winding. When the generator is operating normally, the excitation current generates a magnetic field in the winding of each pole, and the turn-to-turn short circuit will cause the magnetic field of some poles to weaken or not generate a magnetic field, thereby reducing the efficiency of the generator. In severe cases, it may even cause equipment damage or unit shutdown.

[0003] Many reasons can lead to stator turn-to-turn short circuit failures, such as manufacturing process problems: during the generator manufacturing process, due to unqualified insulation material quality, irregular coil winding, etc., the operating environment affects: during the operation of the generator, due to the influence of environmental factors such as high temperature, high humidity, and vibration, the insulation between the winding turns is aged and damaged. When the degree of stator turn-to-turn short circuit is not serious, it may not affect the normal operation of the generator in the short term. If it is ignored, the fault will spread, which will cause the reactive power output of the generator to decrease and the excitation current of the rotor winding to increase, which will lead to the burning of the unit shaft neck and bearing and the intensification of the vibration of the unit, and even cause a fire, causing serious damage to the equipment, thereby seriously threatening the safe and stable operation of the generator set and the power grid.

[0004] Existing research mainly identifies the short-circuit fault between the inner rotor generator turn by detecting the generator vibration signal. However, due to the special structure of the outer rotor permanent magnet generator, the outer rotor is in a rotating state during operation, which makes it impossible to fix the vibration sensor. Therefore, it is impossible to accurately identify the short-circuit fault between the outer rotor permanent magnet generator turn by turn through the vibration signal, and it is usually ignored. This is not conducive to the research, diagnosis and prevention of the short-circuit fault between the generator turn.

[0005] Therefore, it is an urgent problem for technical personnel in this field to propose a novel and simple stator turn-to-turn short-circuit fault detection method, which can identify the stator turn-to-turn short-circuit fault of the outer rotor permanent magnet generator online without the help of a vibration sensor. Summary of the invention

[0006] The purpose of the present invention is to provide a method for identifying stator turn-to-turn short-circuit faults of an outer rotor permanent magnet generator, which is simple to operate and has high identification accuracy, improves the efficiency and accuracy of identifying stator turn-to-turn short-circuit faults of the generator, fills the current deficiencies and shortcomings in identifying turn-to-turn short-circuit faults, and lays a foundation for the research, diagnosis and prevention of stator turn-to-turn short-circuit faults of synchronous generators.

[0007] To achieve the above object, the present invention provides a method for identifying a stator turn-to-turn short circuit fault of an outer rotor permanent magnet generator, comprising the following steps:

[0008] S1. Measure the torque signal of the outer rotor permanent magnet generator by detecting the unit;

[0009] S2. Process the torque signal to determine the inter-turn short circuit fault of the outer rotor permanent magnet generator.

[0010] Preferably, S1 specifically includes the following steps:

[0011] S1.1. Select a suitable torque and speed sensor according to the rated torque and rated speed of the outer rotor permanent magnet generator;

[0012] S1.2. Use two sets of couplings to install the torque and speed sensors on the outer rotor shaft of the outer rotor permanent magnet generator, and adjust the center heights of the outer rotor shaft of the outer rotor permanent magnet generator, the couplings and the torque and speed sensors to be on the same horizontal line;

[0013] S1.3. The torque and speed sensor converts the torque and speed signals of the outer rotor permanent magnet generator during operation into electrical signals, and transmits the electrical signals to the signal processor through the data transmission line. The signals processed by the signal processor are fed back to the computer terminal through the data transmission line and the signal acquisition instrument. The computer terminal obtains the generator torque time domain signal after processing.

[0014] Preferably, S2 specifically includes the following steps:

[0015] S2.1, the computer terminal obtains the generator frequency domain signal by Fourier transforming the generator torque time domain signal;

[0016] S2.2. Identify the stator turn-to-turn short circuit fault of the outer rotor permanent magnet generator by judging the amplitude of the specific frequency band of the generator torque frequency domain signal.

[0017] Preferably, in S2.1, the length, period and amplitude of the signal processing function are adjusted according to the operating parameters of the outer rotor permanent magnet generator, and the signal processing function is used to process the obtained outer rotor permanent magnet generator torque frequency domain signal to improve the quality of the generator torque frequency domain signal and extract a specific frequency band.

[0018] Preferably, in S2.2, the stator turn-to-turn short circuit fault of the outer rotor permanent magnet generator is identified by using the energy formula of the air gap magnetic field and the generator torque formula;

[0019] The air gap magnetomotive force of the outer rotor generator under normal conditions and short-circuit fault conditions is expressed as:

[0020]

[0021] Among them, β and β 1 is the phase angle of the magnetomotive force between the normal current and the short-circuit current of the short-circuit winding, Z is the number of stator slots, n s is the number of short-circuit turns, R f is the stator winding short-circuit contact resistance, R 1 is the resistance per turn of the stator winding, L is the self-inductance coefficient of the short-circuit winding, ω is the rotor electrical angular frequency, k is the harmonic order, and k is an odd number, p is the generator level, The space order is v and the time order is μ. The phase angle of the magnetomotive force generated by the normal winding is θ v1,μ1 The space order is v 1 The time order is μ 1 The phase angle of the magnetomotive force generated by the short-circuited winding, α s is the mechanical angle, F k is the normal winding magnetomotive force amplitude with time and space orders both k, F v,μ is the normal winding magnetomotive force amplitude with spatial order v and time order μ, v and v 1 are spatial orders, μ and μ 1 are all time orders, where v, v 1 , μ and μ 1 are all odd numbers. Since the three-phase windings are asymmetrical after short circuit, v 1 and μ 1 It can be a multiple of 3. Under normal circumstances, due to the symmetry of the three-phase winding, v and μ cannot be a multiple of 3, v = 1, -5, 7, -11, 13..., μ = 1, -5, 7, -11, 13..., is the normal current magnetomotive force of the short-circuited winding with a spatial order of v and a time order of μ, The space order is v 1 The time order is μ 1 The short-circuit current magnetomotive force of the short-circuit winding;

[0022] The energy formula of the synchronous generator air gap magnetic field is expressed as:

[0023]

[0024] Among them, B(a s ,t) is the generator flux density, μ 0is the vacuum magnetic permeability, D is the average diameter of the air gap, W is the air gap magnetic field energy, V is the effective volume inside the generator air gap involved in electromechanical energy conversion, f(a s ,t) is the generator air gap magnetomotive force, Λ(a s ,t) is the air gap permeability per unit area;

[0025] Substituting the generator gap magnetomotive force formula under normal conditions and stator turn-to-turn short-circuit fault into the energy formula of the synchronous generator air gap magnetic field, it is expressed as:

[0026]

[0027] Among them, Λ 0 is the fundamental wave of air gap permeance;

[0028] The generator torque formula is expressed as:

[0029]

[0030] in, is the partial differential symbol, and ψ is the power factor angle inside the generator.

[0031] Therefore, the present invention adopts the above-mentioned method for identifying stator turn-to-turn short-circuit faults of an outer rotor permanent magnet generator, which is simple to operate and has high identification accuracy, improves the efficiency and accuracy of identifying stator turn-to-turn short-circuit faults of the generator, fills the current deficiencies and shortcomings in the identification of turn-to-turn short-circuit faults, and lays a foundation for the research, diagnosis and prevention of stator turn-to-turn short-circuit faults of synchronous generators.

[0032] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of a detection unit of a stator turn-to-turn short-circuit fault identification method for an outer rotor permanent magnet generator of the present invention;

[0034] Figure 2 The present invention is a flow chart of a method for identifying stator turn-to-turn short-circuit faults of an outer rotor permanent magnet generator.

[0035] Reference numerals

[0036] 1. Outer rotor permanent magnet generator; 2. Torque and speed sensor; 3. Signal processor; 4. Signal acquisition instrument; 5. Computer terminal. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0038] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] Embodiment 1

[0040] like Figure 1 to Figure 2 As shown, the present invention provides a method for identifying stator turn-to-turn short circuit faults of an outer rotor permanent magnet generator, comprising the following steps:

[0041] S1, measuring the torque signal of the outer rotor permanent magnet generator 1 by detecting the unit; specifically comprising the following steps:

[0042] S1.1, select a suitable torque and speed sensor 2 according to the rated torque and rated speed of the outer rotor permanent magnet generator 1;

[0043] S1.2. Use two sets of couplings to install the torque and speed sensor 2 on the outer rotor shaft of the outer rotor permanent magnet generator 1, and adjust the center heights of the outer rotor shaft of the outer rotor permanent magnet generator 1, the coupling and the torque and speed sensor 2 to be on the same horizontal line;

[0044] S1.3, the torque and speed sensor 2 converts the torque and speed signals of the outer rotor permanent magnet generator 1 during operation into electrical signals, and transmits the electrical signals to the signal processor 3 through the data transmission line. The signal processed by the signal processor 3 is fed back to the computer terminal 5 through the data transmission line and the signal acquisition instrument 4. The computer terminal 5 obtains the generator torque time domain signal after processing.

[0045] S2, performing signal processing on the torque signal to determine the inter-turn short circuit fault of the outer rotor permanent magnet generator 1; specifically comprising the following steps:

[0046] S2.1, the computer terminal 5 obtains the generator frequency domain signal by Fourier transforming the generator torque time domain signal;

[0047] The length, period and amplitude of the signal processing function are adjusted according to the operating parameters of the outer rotor permanent magnet generator 1, and the obtained torque frequency domain signal of the outer rotor permanent magnet generator 1 is processed using the signal processing function to improve the quality of the generator torque frequency domain signal and extract a specific frequency band.

[0048] S2.2, identifying the stator turn-to-turn short circuit fault of the outer rotor permanent magnet generator 1 by judging the amplitude of a specific frequency segment of the generator torque frequency domain signal;

[0049] The stator turn-to-turn short circuit fault of the outer rotor permanent magnet generator 1 is identified by the energy formula of the air gap magnetic field and the generator torque formula;

[0050] The air gap magnetomotive force of the outer rotor generator under normal conditions and short-circuit fault conditions is expressed as:

[0051]

[0052] Among them, β and β 1 is the phase angle of the magnetomotive force between the normal current and the short-circuit current of the short-circuit winding, Z is the number of stator slots, n s is the number of short-circuit turns, R f is the stator winding short-circuit contact resistance, R 1 is the resistance per turn of the stator winding, L is the self-inductance coefficient of the short-circuit winding, ω is the rotor electrical angular frequency, k is the harmonic order, and k is an odd number, p is the generator level, The space order is v and the time order is μ. The phase angle of the magnetomotive force generated by the normal winding is θ v1,μ1 The space order is v 1 The time order is μ 1 The phase angle of the magnetomotive force generated by the short-circuited winding, α s is the mechanical angle, F k is the normal winding magnetomotive force amplitude with time and space orders both k, F v,μ is the normal winding magnetomotive force amplitude with spatial order v and time order μ, v and v 1 are spatial orders, μ and μ 1 are all time orders, where v, v 1 , μ and μ 1 are all odd numbers. Since the three-phase windings are asymmetrical after short circuit, v 1 and μ 1 It can be a multiple of 3. Under normal circumstances, due to the symmetry of the three-phase winding, v and μ cannot be a multiple of 3, v = 1, -5, 7, -11, 13..., μ = 1, -5, 7, -11, 13..., is the normal current magnetomotive force of the short-circuited winding with a spatial order of v and a time order of μ, The space order is v 1 The time order is μ 1The short-circuit current magnetomotive force of the short-circuit winding;

[0053] The energy formula of the synchronous generator air gap magnetic field is expressed as:

[0054]

[0055] Among them, B(a s ,t) is the generator flux density, μ 0 is the vacuum magnetic permeability, D is the average diameter of the air gap, W is the air gap magnetic field energy, V is the effective volume inside the generator air gap involved in electromechanical energy conversion, f(a s ,t) is the generator air gap magnetomotive force, Λ(a s ,t) is the air gap permeability per unit area;

[0056] Substituting the generator gap magnetomotive force formula under normal conditions and stator turn-to-turn short-circuit fault into the energy formula of the synchronous generator air gap magnetic field, it is expressed as:

[0057]

[0058] Among them, Λ 0 is the fundamental wave of air gap permeance;

[0059] The generator torque formula is expressed as:

[0060]

[0061] in, is the partial differential symbol, and ψ is the power factor angle inside the generator.

[0062] According to the generator torque formula and the energy formula of the air gap magnetic field, it can be known that under normal circumstances, the torque frequency domain signal contains DC components and sixth harmonic components during the operation of the generator. In the case of a short circuit fault between the stator turns of the generator, the torque frequency domain signal contains DC components, second harmonic components, fourth harmonic components and sixth harmonic components. Therefore, the generator can determine whether the second harmonic component and the fourth harmonic component appear in the torque frequency domain signal and then determine the stator turn short circuit fault.

[0063] After the computer obtains the generator torque frequency domain signal through Fourier transformation, it uses a suitable signal processing function to process the generator torque frequency domain signal, adjusts the length, period, amplitude and other parameters of the signal processing function according to the generator operating parameters, filters out clutter, improves signal quality, and enhances the generator's second harmonic component and fourth harmonic component signals. After the torque frequency domain signal is processed, it is judged that when the generator has the second harmonic component and the fourth harmonic component signal at the same time, it can be judged that the generator has a stator turn-to-turn short circuit fault.

[0064] Therefore, the present invention adopts the above-mentioned method for identifying stator turn-to-turn short-circuit faults of an outer rotor permanent magnet generator, which is simple to operate and has high identification accuracy, improves the efficiency and accuracy of identifying stator turn-to-turn short-circuit faults of the generator, fills the current deficiencies and shortcomings in the identification of turn-to-turn short-circuit faults, and lays a foundation for the research, diagnosis and prevention of stator turn-to-turn short-circuit faults of synchronous generators.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for identifying stator turn-to-turn short-circuit faults in an outer rotor permanent magnet generator. Features: The following steps are involved: S1. Measure the torque signal of the outer rotor permanent magnet generator by detecting the unit; S2. Process the torque signal to determine the inter-turn short circuit fault of the outer rotor permanent magnet generator.

2. A method for identifying stator turn-to-turn short circuit faults of an outer rotor permanent magnet generator according to claim 1, Features: S1 specifically includes the following steps: S1.

1. Select a suitable torque and speed sensor according to the rated torque and rated speed of the outer rotor permanent magnet generator; S1.

2. Use two sets of couplings to install the torque and speed sensors on the outer rotor shaft of the outer rotor permanent magnet generator, and adjust the center heights of the outer rotor shaft of the outer rotor permanent magnet generator, the couplings and the torque and speed sensors to be on the same horizontal line; S1.

3. The torque and speed sensor converts the torque and speed signals of the outer rotor permanent magnet generator during operation into electrical signals, and transmits the electrical signals to the signal processor through the data transmission line. The signals processed by the signal processor are fed back to the computer terminal through the data transmission line and the signal acquisition instrument. The computer terminal obtains the generator torque time domain signal after processing.

3. A method for identifying stator turn-to-turn short circuit faults of an outer rotor permanent magnet generator according to claim 2, Features: S2 specifically includes the following steps: S2.1, the computer terminal obtains the generator frequency domain signal by Fourier transforming the generator torque time domain signal; S2.

2. Identify the stator turn-to-turn short circuit fault of the outer rotor permanent magnet generator by judging the amplitude of the specific frequency band of the generator torque frequency domain signal.

4. A method for identifying stator turn-to-turn short circuit faults of an outer rotor permanent magnet generator according to claim 3, Features: In S2.1, the length, period and amplitude of the signal processing function are adjusted according to the operating parameters of the outer rotor permanent magnet generator, and the signal processing function is used to process the obtained outer rotor permanent magnet generator torque frequency domain signal to improve the generator torque frequency domain signal quality and extract specific frequency bands.

5. A method for identifying stator turn-to-turn short-circuit faults of an outer rotor permanent magnet generator according to claim 3, Features: In S2.2, the energy formula of the air gap magnetic field and the generator torque formula are used to identify the stator turn-to-turn short circuit fault of the outer rotor permanent magnet generator; The air gap magnetomotive force of the outer rotor generator under normal conditions and short-circuit fault conditions is expressed as: Among them, β and β 1 is the phase angle of the magnetomotive force between the normal current and the short-circuit current of the short-circuit winding, Z is the number of stator slots, n s is the number of short-circuit turns, R f is the stator winding short-circuit contact resistance, R 1 is the resistance per turn of the stator winding, L is the self-inductance coefficient of the short-circuit winding, ω is the rotor electrical angular frequency, k is the harmonic order, and k is an odd number, p is the generator series, θ v1,μ1 The space order is v 1 The time order is μ 1 The phase angle of the magnetomotive force generated by the short-circuited winding is The space order is v and the time order is μ. The phase angle of the magnetomotive force generated by the normal winding is α s is the mechanical angle, F k is the normal winding magnetomotive force amplitude with time and space orders both k, F v,μ is the normal winding magnetomotive force amplitude with spatial order v and time order μ, v and v 1 are spatial orders, μ and μ 1 are all time orders, where v, v 1 , μ and μ 1 are all odd numbers. Since the three-phase windings are asymmetrical after short circuit, v 1 and μ 1 It can be a multiple of 3. Under normal circumstances, due to the symmetry of the three-phase winding, v and μ cannot be a multiple of 3, v = 1, -5, 7, -11, 13..., μ = 1, -5, 7, -11, 13..., is the normal current magnetomotive force of the short-circuited winding with a spatial order of v and a time order of μ, The space order is v 1 The time order is μ 1 The short-circuit current magnetomotive force of the short-circuit winding; The energy formula of the synchronous generator air gap magnetic field is expressed as: Among them, B(a s ,t) is the generator flux density, μ 0 is the vacuum magnetic permeability, D is the average diameter of the air gap, W is the air gap magnetic field energy, V is the effective volume inside the generator air gap involved in electromechanical energy conversion, f(a s ,t) is the generator air gap magnetomotive force, Λ(a s ,t) is the air gap permeability per unit area; Substituting the generator gap magnetomotive force formula under normal conditions and stator turn-to-turn short-circuit fault into the energy formula of the synchronous generator air gap magnetic field, it is expressed as: Among them, Λ 0 is the fundamental wave of air gap permeance; The generator torque formula is expressed as: in, is the partial differential symbol, and ψ is the power factor angle inside the generator.

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