CN111624515B - Method and device for detecting turn-to-turn short circuit of stator winding of early synchronous generator - Google Patents

Abstract

The invention discloses an early synchronous generator stator winding inter-turn short circuit detection method and device. The method comprises: real-time measurement of a stator winding temperature signal, a stator vertical vibration signal and a stator three-phase current signal; The vertical vibration signal is converted into a spectrum signal, and the different frequency components in the spectrum signal are compared with the corresponding frequency components in the stator normal vibration data samples, and the stator winding temperature signal is combined to determine whether the synchronous generator has an inter-turn short-circuit fault of the stator winding; if There is a method of determining the short-circuit position by using the number of the fiber Bragg grating optical sensor, and comparing the three-phase current signal of the stator with the normal three-phase current data sample of the stator to calculate the short-circuit fault degree. The invention has a simple structure, can identify the fault location and degree of the early synchronous generator stator winding inter-turn short-circuit fault, and has a simple and easy detection method.

Description

A method and device for detecting inter-turn short circuit of stator winding of early synchronous generator

technical field

The invention relates to the technical field of equipment state monitoring and testing, and more particularly to a method and a device for identifying the degree and position of short-circuit faults between turns of a synchronous generator stator winding by using actual stator winding temperature signals, stator vibration signals and stator current changes.

Background technique

The stator winding short-circuit fault is the most common fault in the motor, which will lead to phase-to-phase short-circuit and ground fault in severe cases. The main cause of the short circuit is the breakdown of the insulating material, which is caused by the combination of various stresses (thermal, electrical, mechanical stress) acting on the winding during its service life. This insulation breakdown can cause a turn-to-turn short-circuit fault, which in turn results in a huge temperature rise in the short-circuited windings, exacerbating the short-circuit level, and ultimately causing the motor to fail. Therefore, the detection of early turn-to-turn shorts in the stator windings is critical to prevent serious damage to the motor and reduce associated repair costs and production losses.

However, the existing technologies are mostly based on online monitoring and analysis of separate electrical parameters (stator current, phase voltage, impedance, etc.) and vibration parameters (stator-rotor vibration, stator end winding vibration). However, the above techniques are limited in their effective identification of early fault stages of inter-turn short circuits, such as load changes, power supply imbalances and inherent asymmetries. These subtle changes in motor operating conditions can greatly affect their diagnostic accuracy. In this way, it is impossible to take timely protection measures to curb the development of faults and minimize losses at the initial stage of formation and development of inter-turn short circuits.

Therefore, how to provide a method and device for detecting a short circuit between turns of an early synchronous generator stator winding is an urgent problem to be solved by those skilled in the art.

SUMMARY OF THE INVENTION

In view of this, the present invention provides an early synchronous generator stator winding inter-turn short-circuit detection method and device, which can identify the fault location and degree of the early synchronous generator stator winding inter-turn short-circuit fault, which is simple and easy to implement, and can compensate for synchronous generators. The shortcomings of the traditional monitoring technology based on the individual electrical parameters and mechanical parameters of the generator provide important reference materials for the early identification and monitoring of the inter-turn short circuit of the stator winding of the synchronous generator.

In order to achieve the above object, the present invention adopts the following technical solutions:

An early synchronous generator stator winding inter-turn short circuit detection device, comprising a synchronous generator, a vertical vibration speed sensor, a current transformer, a fiber Bragg grating optical sensor, a fiber grating regulator, a DC drive motor, an upper computer and a lower computer, The vertical vibration speed sensor is vertically attached to the upper end of the stator of the synchronous generator, the current transformer is connected to the outlet end of the stator winding of the synchronous generator, and the fiber Bragg grating optical sensor is embedded in the synchronous generator in the stator slot, and the vertical vibration velocity sensor and the current transformer are connected to the upper computer through the lower computer, and the fiber Bragg grating optical sensor is connected to the upper computer through the fiber Bragg grating adjustment instrument and the upper computer. connected, the synchronous generator and the DC drive motor are connected.

Further, the fiber Bragg grating optical sensors are arranged in the stator slots where the upper layer winding and the lower layer winding of each coil of each phase winding of the stator are located, and the fiber Bragg grating optical sensors are sequentially numbered counterclockwise.

An early synchronous generator stator winding inter-turn short circuit detection method, comprising:

Step 1: Use the fiber Bragg grating optical sensor, the vertical vibration velocity sensor and the current transformer to measure the temperature signal of the stator winding, the vertical vibration signal of the stator and the three-phase current signal of the stator respectively in real time;

Step 2: Transform the stator vertical vibration signal into a spectrum signal by using fast Fourier transform, compare the different frequency components in the spectrum signal with the corresponding frequency components in the stator normal vibration data sample, and convert the Comparing the temperature signal of the stator winding with the normal temperature data sample of the stator winding, if the amplitude of the double frequency of the stator increases, the amplitude and vibration characteristics of the quadruple frequency and the sixth frequency appear, and the temperature of the stator winding rises, it indicates that the synchronous generator has stator winding turns. short circuit fault;

Step 3: Use the number of the fiber Bragg grating optical sensor to determine the short-circuit position, and compare the three-phase current signal of the stator with the normal three-phase current data sample of the stator to calculate the short-circuit fault degree.

Further, the acquisition process of the stator normal vibration data sample and the stator winding normal temperature data sample is:

After the synchronous generator assembly machine is debugged and all the indicators tend to be normal, the vertical vibration speed sensor and the fiber Bragg grating optical sensor are used to measure the vertical vibration speed of the stator and the temperature of the stator winding, respectively. Solve the average value of the stator vertical vibration speed and the average value of the stator winding temperature to obtain the normal temperature data sample of the stator winding, filter and denoise the average value of the stator vertical vibration speed and use the FFT algorithm to transform For the frequency spectrum signal, extract and record the stator vibration characteristics and amplitudes from one frequency to six times frequency to obtain the normal vibration data samples of the stator.

Further, the acquisition process of the stator normal three-phase current data sample is:

After the generator assembly is debugged and all the indicators tend to be in a normal state, ten groups of stator phase currents are measured through the current transformer, and the three-phase current signals of the ten groups of stator phase currents are extracted to solve ten groups of three phase currents respectively. The average value of the phase current signal to obtain the sample data of the stator phase current.

Further, the calculation formula for the degree of short-circuit fault is:

In the formula, n _A , n _B and n _C are the current short-circuit fault degree of A-phase, B-phase and C-phase respectively, i _AN and i _AF are the stator A-phase current under the normal operation of the generator and the short circuit between turns of the stator winding, i _BN and i _BF is the stator B-phase current under the normal operation of the generator and the inter-turn short circuit of the stator winding, i _CN and i _CF are the stator C-phase current under the normal operation of the generator and the inter-turn short circuit of the stator winding, and the calculation formula is as follows:

In the formula, w _c is the number of winding turns of one phase of the stator winding, γ is the harmonic order, k _wγ is the γ-th harmonic winding distribution factor, l is the effective length of the stator winding, and v is the air-gap magnetic density cutting the winding line. Speed, z is the winding impedance, B _N and B _F are the air gap composite magnetic density under the normal operation of the generator and the short circuit between turns of the stator winding, the calculation formula is as follows:

In the formula, ω is the electrical angle frequency, I _f2 is the current peak value induced in the field winding under the short circuit between turns of the stator, N is the number of turns of the field winding, η is the proportional coefficient of the stator magnetic potential and the rotor magnetic potential, and p is the generator pole logarithm, α _m is the circumferential angle used to characterize the position of the air gap, ψ is the internal power angle of the generator, t is the time, Λ ₀ is the air gap permeance per unit area, which is a constant, and I _f0 is the generator under normal operation. The excitation current of , is obtained by the following formula:

In the formula, f _N and f _F are the air-gap magnetic potential under the normal operation of the generator and the short circuit between turns of the stator winding, F _r and F _r1 are the rotor magnetic potential under the normal operation of the generator and the short circuit between the turns of the stator winding, F _s and F _s1 is the stator magnetomotive force under normal operation of the generator and short circuit between turns of the stator winding.

As can be seen from the above technical solutions, compared with the prior art, the present invention provides a method and device for detecting short-circuit between turns of an early synchronous generator stator winding, which utilizes a fiber Bragg grating optical sensor to acutely capture changes in ambient temperature. In addition, the stator winding will have obvious temperature rise under the early stator inter-turn short-circuit fault. Through the electromechanical and thermal joint diagnosis method of the stator vertical vibration signal, stator current signal and stator winding temperature signal, the early synchronous generator stator winding turns are detected. The fault degree and fault location of the short circuit.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative work.

FIG. 1 is a flowchart of a method for detecting inter-turn short-circuits in an early synchronous generator stator winding provided by the present invention.

Figure 2 is a schematic diagram of the connection of the early synchronous generator stator winding inter-turn short circuit detection device provided by the present invention.

3 is a schematic diagram of the arrangement of the fiber Bragg grating optical sensor provided in the present invention in the stator slot.

in,

1. Synchronous generator, 2. Vertical vibration speed sensor, 3. Current transformer, 4. Fiber Bragg grating optical sensor, 5. Fiber Bragg grating regulator, 6. DC drive motor, 7. Upper computer, 8. Lower computer , 9, stator slot, 10, stator winding, 11, stator core.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

As shown in FIG. 2 , an embodiment of the present invention discloses an early synchronous generator stator winding inter-turn short circuit detection device, including a synchronous generator 1 , a vertical vibration velocity sensor 2 , a current transformer 3 , and a fiber Bragg grating optical sensor 4 , fiber grating adjustment instrument 5, DC drive motor 6, upper computer 7 and lower computer 8, the vertical vibration speed sensor 2 is used to measure the vertical vibration of the stator, and the vertical vibration speed sensor 2 is vertically adsorbed on the synchronous generator through the bottom magnet At the upper end of the stator of 1, the collected stator vertical vibration speed signal is subjected to A/D conversion, filtering, denoising and sampling through the lower computer 8, and finally input to the upper computer 7 for storage, and the current transformer 3 is connected to the stator of the synchronous generator 1. The outgoing end of the winding is used to measure the stator phase current. Specifically, three current transformers are provided, corresponding to the three-phase current of the stator.

As shown in FIG. 3, the fiber Bragg grating optical sensor 4 is embedded in the center position of the stator slot 9 to measure the temperature of the stator winding 10. The A, B, and C three-phase windings are placed in the stator slot 9, and the number of parallel branches is 2. The stacking method is double-layer short-distance stacked windings, that is, each phase winding in Figure 3 has 12 coils, which are the upper-layer windings A1+, A2+, A3+, A4+, A5+, and A6+ of the A1 branch, which are placed in slots 1-6. Upper layer, lower layer windings A15-, A16-, A17-, A18-, A19-, A20-, placed in the lower layer of slots 15-20, A2 branch upper layer windings A19+, A20+, A21+, A22+, A23+, A24+, placed On the upper layer of slots 19-24, the lower windings A33-, A34-, A35-, A36-, A1-, A2- are placed on the lower layers of slots 33-36 and 1-2; upper winding C7+ of branch C1 , C8+, C9+, C10+, C11+, C12+, placed in the upper layer of slots 7-12, C21-, C22-, C23-, C24-, C25-, C26- of the lower windings of the C1 branch, placed in No. 21-26 The lower layer of the slot, the upper layer windings C25+, C26+, C27+, C28+, C29+, C30+ of the C2 branch are placed on the upper layer of the slots 25-30, and the lower layer windings of the C2 branch are C3-, C4-, C5-, C6-, C7- , C8-, placed on the lower layer of slots 3-8; B1 branch upper windings B13+, B14+, B15+, B16+, B17+, B18+, placed on the upper layer of slots 13-18, B1 branch lower windings B27-, B28 -, B29-, B30-, B31-, B32-, placed in the lower layer of slots 27-32, B2 branch upper windings B31+, B32+, B33+, B34+, B35+, B36+, placed in the upper layer of slots 31-36 , B2 branch lower windings B9-, B10-, B11-, B12-, B13-, B14-, placed in the lower layer of slots 9-14. A fiber Bragg grating optical sensor 4 is provided in the stator slot where the upper layer winding and the lower layer winding of each coil of each phase winding of the stator are located, and a total of 72 fiber Bragg grating optical sensors are installed in each of the windings of each phase. In the stator slot 9 where the coils are located, the fiber Bragg grating optical sensors 4 on the coils of each phase winding are numbered in the counterclockwise direction, that is, the six fiber Bragg grating optical sensors on the upper winding of the A1 branch of the A-phase winding coil are numbered sequentially. Sensor 4, numbered counterclockwise as 1, 2, 3, 4, 5, 6, 6 fiber Bragg grating optical sensors 4 on the lower winding of branch A1, numbered counterclockwise as 7, 8, 9 , 10, 11, 12, 6 fiber Bragg grating optical sensors 4 on the upper winding of the A2 branch, numbered 13, 14, 15, 16, 17, 18 in the counterclockwise direction, 6 on the lower winding of the A2 branch The fiber Bragg grating optical sensors 4 are numbered 19, 20, 21, 22, 23, and 24 in the counterclockwise direction, and the six fiber Bragg grating optical sensors 4 on the upper winding of the B1 branch of the B-phase winding coil are reversed. The clockwise direction is sequentially numbered 25, 26, 27, 28, 29, 30, and the six fiber Bragg grating optical sensors 4 on the lower winding of the B1 branch are sequentially numbered 31, 32, 33, 34, 35, 36. The fiber Bragg grating optical sensors 4 on the upper windings of the B2 branch are numbered 37, 38, 39, 40, 41, and 42 in the counterclockwise direction, and the six fiber Bragg grating optical sensors 4 on the lower windings of the B2 branch , numbered as 43, 44, 45, 46, 47, 48 in the counterclockwise direction, and the six fiber Bragg grating optical sensors 4 on the upper winding of the C1 branch of the C-phase winding coil are numbered in the counterclockwise direction as 49, 50, 51, 52, 53, 54, 6 fiber Bragg grating optical sensors 4 on the lower winding of branch C1, numbered counterclockwise as 55, 56, 57, 58, 59, 60, upper winding of branch C2 The six fiber Bragg grating optical sensors 4 on the upper side are numbered 61, 62, 63, 64, 65, 66 in the counterclockwise direction, and the six fiber Bragg grating optical sensors 4 on the lower winding of the C2 branch are counterclockwise. The numbers are 67, 68, 69, 70, 71, and 72 in sequence, and then the fiber Bragg grating optical sensor 4 and the collected temperature signal are input to the fiber Bragg grating demodulator 5 and uploaded to the host computer.

As shown in Figure 1, based on the early synchronous generator stator winding inter-turn short-circuit detection method of the above-mentioned device, the method measures the temperature signal of the stator winding, the vertical vibration signal of the stator, and the stator current in real time as the monitoring and contrast quantities, and uses the fiber Bragg grating optical fiber Bragg grating optical The sensor collects the winding temperature signal, and transmits it to the host computer through the fiber grating modulator to determine whether the winding has a significant temperature rise. The vertical vibration speed sensor collects the stator vertical vibration speed signal, and then filters and de-noises the signal and transforms it into a spectrum signal using the FFT algorithm. , and then compare the different frequency components in the transformed spectrum signal with the corresponding frequency components in the normal vibration data samples of the stator, and combine the mechanical parameters and thermal parameters to determine whether the inter-turn short circuit and the position of the short circuit occur, and the current transformer induces the stator every Phase current, obtain the average value of each phase current data, and calculate the short-circuit degree in combination with the normal stator phase current.

Specifically include the following steps:

Step 1: Use the fiber Bragg grating optical sensor, the vertical vibration velocity sensor and the current transformer to measure the temperature signal of the stator winding, the vertical vibration signal of the stator and the three-phase current signal of the stator respectively in real time;

Step 2: Transform the stator vertical vibration signal into a spectrum signal by using fast Fourier transform, compare the different frequency components in the spectrum signal with the corresponding frequency components in the stator normal vibration data sample, and convert the Comparing the temperature signal of the stator winding with the normal temperature data sample of the stator winding, if the amplitude of the double frequency of the stator increases, the vibration characteristics and amplitude of the quadruple frequency and the sixfold frequency appear, and the temperature of the stator winding rises, it means that the synchronous generator exists between turns of the stator winding. short circuit fault;

Step 3: A fiber Bragg grating optical sensor is respectively set in the stator slot where the upper winding and the lower winding of each coil of each phase winding of the stator are located, and the corresponding fiber Bragg grating optical sensor is found by comparing the temperature rise data, so as to The short-circuit position is judged by the number of the optical fiber Bragg grating optical sensor, and the short-circuit fault degree is calculated by comparing the stator three-phase current signal extracted by the current transformer with the normal three-phase current data sample of the stator.

The four simultaneous formulas used to solve the short-circuit degree of the stator winding are:

的和，在运行中可用专用仪表测取得到，t为时间。式(1)中除了励磁电流I_f0外，其余各参数均为电机自身固有参数，可从电机装备资料中直接查取获得。In formula (1), f _N and f _F are the air-gap magnetic potential under the normal operation of the generator and the short circuit between turns of the stator winding; F _r and F _r1 are the rotor magnetic potential under the normal operation of the generator and the short circuit between the turns of the stator winding, F _s and F _s1 are the stator magnetic potential under the normal operation of the generator and the inter-turn short circuit of the stator winding, I _f0 is the excitation current of the generator under normal operation, and I _f2 is the current peak value induced in the excitation winding under the stator inter-turn short circuit , N is the number of turns of the excitation winding, η is the proportional coefficient of the stator magnetic potential and the rotor magnetic potential, p is the number of pole pairs of the generator; α _m is the circumferential angle used to characterize the position of the air gap, ψ is the generator internal power angle, and the numerical value The upper is the generator power angle θ and the power factor angle

The sum of , can be obtained by measuring with special instrument during operation, and t is time. In formula (1), except the excitation current I _f0 , the other parameters are the inherent parameters of the motor itself, which can be directly obtained from the motor equipment data.

In formula (2), B _N and B _F are the combined air-gap magnetic density under the normal operation of the generator and the short circuit between turns of the stator winding, and Λ ₀ is the air-gap permeance per unit area, which is a constant.

In formula (3), i _AN and i _AF are the stator A-phase current under the normal operation of the generator and the inter-turn short circuit of the stator winding, i _BN and i _BF are the stator B-phase current under the normal operation of the generator and the inter-turn short circuit of the stator winding, i _CN and i _CF are the C-phase current of the stator under the normal operation of the generator and the inter-turn short circuit of the stator winding, w _c is the number of turns of the stator winding one phase, γ is the harmonic order, and k _wγ is the γ-th harmonic winding distribution factor , l is the effective length of the stator winding, v is the linear velocity of the air-gap magnetic density cutting the winding, and z is the winding impedance.

According to the above three formulas, the final fault degree expression of the inter-turn short-circuit fault of the stator winding of the synchronous generator is obtained as shown in formula (4). Among them, n _A , n _B and n _C are the short-circuit fault degree of A-phase, B-phase and C-phase respectively.

Claims (3)

1. an early synchronous generator stator winding inter-turn short-circuit detection method based on an early synchronous generator stator winding inter-turn short-circuit detection device, is characterized in that, comprising: Step 1: use the fiber Bragg grating optical sensor (4), the vertical vibration velocity sensor (2) and the current transformer (3) to measure the temperature signal of the stator winding, the vertical vibration signal of the stator and the three-phase current signal of the stator respectively in real time; Step 2: Transform the stator vertical vibration signal into a spectrum signal by using fast Fourier transform, compare the different frequency components in the spectrum signal with the corresponding frequency components in the stator normal vibration data sample, and convert the Comparing the temperature signal of the stator winding with the normal temperature data sample of the stator winding, if the amplitude of the double frequency of the stator increases, the amplitude and vibration characteristics of the quadruple frequency and the sixth frequency appear, and the temperature of the stator winding rises, it indicates that the synchronous generator has stator winding turns. short circuit fault; Step 3: use the number of the fiber Bragg grating optical sensor (4) to determine the short-circuit position, and compare the three-phase current signal of the stator with the normal three-phase current data sample of the stator to calculate the short-circuit fault degree; The calculation formula of the short-circuit fault degree is:

In the formula, n _A , n _B and n _C are the current short-circuit fault degree of A-phase, B-phase and C-phase respectively, i _AN and i _AF are the stator A-phase current under the normal operation of the generator and the short circuit between turns of the stator winding, i _BN and i _BF is the stator B-phase current under the normal operation of the generator and the inter-turn short circuit of the stator winding, i _CN and i _CF are the stator C-phase current under the normal operation of the generator and the inter-turn short circuit of the stator winding, and the calculation formula is as follows:

In the formula, w _c is the number of winding turns of one phase of the stator winding, γ is the harmonic order, k _wγ is the γ-th harmonic winding distribution factor, l is the effective length of the stator winding, and v is the air-gap magnetic density cutting the winding line. Speed, z is the winding impedance, B _N and B _F are the air gap composite magnetic density under the normal operation of the generator and the short circuit between turns of the stator winding, the calculation formula is as follows:

In the formula, ω is the electrical angle frequency, I _f2 is the current peak value induced in the field winding under the short circuit between turns of the stator, N is the number of turns of the field winding, η is the proportional coefficient of the stator magnetic potential and the rotor magnetic potential, and p is the generator pole logarithm, α _m is the circumferential angle used to characterize the position of the air gap, ψ is the internal power angle of the generator, t is the time, Λ ₀ is the air gap permeance per unit area, which is a constant, and I _f0 is the generator under normal operation. The excitation current of , is obtained by the following formula:

In the formula, f _N and f _F are the air-gap magnetic potential under the normal operation of the generator and the short circuit between turns of the stator winding, F _r and F _r1 are the rotor magnetic potential under the normal operation of the generator and the short circuit between the turns of the stator winding, F _s and F _s1 is the stator magnetomotive force under normal operation of the generator and short circuit between turns of the stator winding. 2. a kind of early synchronous generator stator winding inter-turn short circuit detection method according to claim 1, is characterized in that, the acquisition process of described stator normal vibration data sample and described stator winding normal temperature data sample is: After the synchronous generator assembly machine is debugged and all the indicators tend to be in a normal state, the vertical vibration velocity sensor (2) and the fiber Bragg grating optical sensor (4) are used to measure the vertical vibration velocity of the stator, respectively. and the stator winding temperature, and solve the average value of the stator vertical vibration speed and the average value of the stator winding temperature to obtain the normal temperature data sample of the stator winding, and filter the average value of the stator vertical vibration speed to remove After the noise, the FFT algorithm is used to transform into a spectrum signal, and the vibration characteristics and amplitudes of the one-octave to six-octave frequency of the stator are extracted and recorded, and the normal vibration data samples of the stator are obtained. 3. a kind of early synchronous generator stator winding inter-turn short circuit detection method according to claim 2, is characterized in that, the acquisition process of described stator normal three-phase current data sample is: After the commissioning of the generator assembly is completed and all the indicators tend to be in a normal state, ten groups of stator phase currents are measured through the current transformer (3), and the three-phase current signals of the ten groups of stator phase currents are extracted to solve the problems respectively. The average value of ten groups of three-phase current signals is obtained to obtain the sample data of stator phase current.

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