CN116559565A - A Method for EMU Traction Transformer Winding State Evaluation under Operating Overvoltage - Google Patents

Abstract

The vehicle-mounted traction transformer is key power equipment for guaranteeing train operation, the health condition of an internal winding of the vehicle-mounted traction transformer directly determines the stable operation of the motor car, and the motor car can experience operation overvoltage when being started or in passing through phase separation, and contains abundant frequency spectrum information. The invention discloses a motor train unit traction transformer winding state evaluation method under operation overvoltage. Firstly, collecting the operation overvoltage of the input end and the output end of the traction transformer, then converting the operation overvoltage to obtain a winding frequency response curve, extracting characteristic parameters representing the winding state from the frequency response curve, and finally evaluating the winding state of the traction transformer based on the characteristic parameters.

Description

A Method for EMU Traction Transformer Winding State Evaluation under Operating Overvoltage

technical field

The invention belongs to the field of performance evaluation of vehicle-mounted traction transformer windings, and in particular relates to a method for evaluating the state of motor train traction transformer windings under operating overvoltage.

Background technique

As the core component of the EMU, the on-board traction transformer undertakes the important mission of providing stable power for the EMU. The failure of the transformer will cause danger and at the same time bring economic losses. As the core component of the transformer, the winding will After that, it will seriously affect the operation of the transformer. The vehicle-mounted traction transformer will experience operating overvoltage when it is started or when it is over-phased. It contains rich high-voltage characteristics and spectrum characteristics, which can characterize the state of the transformer winding. At present, the commonly used methods are studied, but their cost is too high and they are susceptible to field interference. A method that can economically and effectively detect the winding status of vehicle-mounted traction transformers and is not easily disturbed by field information is needed.

In order to overcome the defects of the above-mentioned background technology, the present invention provides a method for evaluating the state of traction transformer windings of motor trains under operating overvoltage, which can effectively and accurately evaluate the state of the vehicle-mounted traction transformer windings. A method for evaluating the state of traction transformer windings of EMUs under operating overvoltage is provided. The method can effectively and accurately evaluate the state of traction transformer windings. The steps of the method are as follows:

Step 1: Obtain the operating overvoltage of the on-board traction transformer

Build an on-board traction transformer test platform based on operating overvoltage, mainly including pulse signal generator (1), protection resistor (2), voltage divider (3), input terminal acquisition device (4), on-board traction transformer (5), The output terminal acquisition device (6), wherein the pulse signal generator (1) passes through the protection resistor (2), and after being divided by the voltage divider (3), it is input to the vehicle-mounted traction transformer (5), and the input terminal acquisition device (4) and The output terminal acquisition device (6) respectively collects the signals before and after the operation overvoltage enters the vehicle traction transformer (5). The test starts, and the amplitude of the pulse signal generator is set to 400V, the pulse width is 400ns, and the pulse front is 30ns. Repeat 10 times For the test, take the average value of the overvoltage signal as the stimulus;

Step 2: Obtain the frequency response curve of the on-board traction transformer winding under operating overvoltage, including:

Using the short-time Fourier transform, the input and output signals are converted into a frequency response curve, as follows:

Among them, Ψ is the window function, τ is the translation amount of the window function, and ω is the angular frequency;

Among them, Y(τ, ω) is the signal after the short-time Fourier transform at the output terminal, and X(τ, ω) is the signal after the short-time Fourier transform at the input terminal;

The third step: extract the characteristic parameters that characterize the winding state, including:

4) Perform pseudo-color processing on the obtained amplitude-frequency curve to obtain a pseudo-color image and a pixel matrix g(x, y) whose size is 512×512, where x and y are the coordinates of the pixel matrix, and the pixel matrix is as follows;

5) Calculate the image gradient of the pseudo-color image:

G _x (x,y)=g(x+1,y)-g(x-1,y) (4)

G _y (x,y)=g(x,y+1)-g(x,y-1) (5)

Wherein, G _x (x, y) represents the horizontal direction gradient of false color image, G _y (x, y) represents the vertical direction gradient of false color image, g (x, y) is the pixel matrix of color image;

6) Calculate the gradient magnitude and gradient direction of the pixel matrix:

Among them, G(x, y) is the gradient magnitude at the pixel point (x, y), and σ(x, y) is the gradient direction at the pixel point (x, y);

Step 4: Evaluate the winding condition of the on-board traction transformer, including:

1) Calculate the evaluation factor K of the winding state of the on-board traction transformer:

2) Use the evaluation factor to evaluate the winding state of the vehicle traction transformer:

K _h is the evaluation factor when the winding state of the vehicle traction transformer is normal, and K _d is the evaluation factor when the winding state of the vehicle traction transformer is faulty. If 0<T<0.78, it means that the winding state of the vehicle traction transformer is normal. If T≥0.78, it means that the vehicle traction transformer winding state is normal. The winding state of the traction transformer is abnormal or faulty and needs to be repaired or replaced.

Description of drawings

Fig. 1 Flowchart of a method for evaluating winding state of EMU traction transformer under operating overvoltage

Accompanying drawing Fig. 2 Based on the operating overvoltage test platform of the vehicle traction transformer winding

Detailed ways

Further describe in detail below in conjunction with accompanying drawing, concrete method step is as follows:

Step 1: Obtain the operating overvoltage of the on-board traction transformer

Build an on-board traction transformer test platform based on operating overvoltage, mainly including pulse signal generator (1), protection resistor (2), voltage divider (3), input terminal acquisition device (4), on-board traction transformer (5), The output terminal acquisition device (6), wherein the pulse signal generator (1) passes through the protection resistor (2), and after being divided by the voltage divider (3), it is input to the vehicle-mounted traction transformer (5), and the input terminal acquisition device (4) and The output terminal acquisition device (6) respectively collects the signals before and after the operation overvoltage enters the vehicle traction transformer (5). The test starts, and the amplitude of the pulse signal generator is set to 400V, the pulse width is 400ns, and the pulse front is 30ns. Repeat 10 times For the test, take the average value of the overvoltage signal as the stimulus;

Step 2: Obtain the frequency response curve of the on-board traction transformer winding under operating overvoltage, including:

Using the short-time Fourier transform, the input and output signals are converted into a frequency response curve, as follows:

Among them, Ψ is the window function, τ is the translation amount of the window function, and ω is the angular frequency;

Among them, Y(τ, ω) is the signal after the short-time Fourier transform at the output terminal, and X(τ, ω) is the signal after the short-time Fourier transform at the input terminal;

The third step: extract the characteristic parameters that characterize the winding state, including:

1) Perform pseudo-color processing on the acquired amplitude-frequency curve to obtain a pseudo-color image and a pixel matrix g(x, y) whose size is 512×512, where x and y are the coordinates of the pixel matrix, and the pixel matrix is as follows;

2) Calculate the image gradient of the pseudo-color image:

G _x (x,y)=g(x+1,y)-g(x-1,y) (4)

G _y (x,y)=g(x,y+1)-g(x,y-1) (5)

Wherein, G _x (x, y) represents the horizontal gradient of the pseudo-color image, G _y (x, y) represents the vertical gradient of the pseudo-color image, and g (x, y) is the pixel matrix of the color image;

3) Calculate the gradient magnitude and gradient direction of the pixel matrix:

Among them, G(x, y) is the gradient magnitude at the pixel point (x, y), and σ(x, y) is the gradient direction at the pixel point (x, y);

Step 4: Evaluate the winding condition of the on-board traction transformer, including:

1) Calculate the evaluation factor K of the winding state of the on-board traction transformer:

2) Use the evaluation factor to evaluate the winding state of the vehicle traction transformer:

K _h is the evaluation factor when the winding state of the vehicle traction transformer is normal, and K _d is the evaluation factor when the winding state of the vehicle traction transformer is faulty. If 0<T<0.78, it means that the winding state of the vehicle traction transformer is normal. If T≥0.78, it means that the vehicle traction transformer winding state is normal. The winding state of the traction transformer is abnormal or faulty and needs to be repaired or replaced.

Claims (1)

1. A motor train unit traction transformer winding state evaluation method under an operation overvoltage, is characterized in that, comprises the following steps: Step 1: Obtain the operating overvoltage of the on-board traction transformer Build an on-board traction transformer test platform based on operating overvoltage, mainly including pulse signal generator (1), protection resistor (2), voltage divider (3), input terminal acquisition device (4), on-board traction transformer (5), The output terminal acquisition device (6), wherein the pulse signal generator (1) passes through the protection resistor (2), and after being divided by the voltage divider (3), it is input to the vehicle-mounted traction transformer (5), and the input terminal acquisition device (4) and The output terminal acquisition device (6) respectively collects the signals before and after the operation overvoltage enters the vehicle traction transformer (5). The test starts, and the amplitude of the pulse signal generator is set to 400V, the pulse width is 400ns, and the pulse front is 30ns. Repeat 10 times For the test, take the average value of the overvoltage signal as the stimulus; Step 2: Obtain the frequency response curve of the on-board traction transformer winding under operating overvoltage, including: Using the short-time Fourier transform, the input and output signals are converted into a frequency response curve, as follows: Among them, Ψ is the window function, τ is the translation amount of the window function, and ω is the angular frequency; Among them, Y(τ, ω) is the signal after the short-time Fourier transform at the output terminal, and X(τ, ω) is the signal after the short-time Fourier transform at the input terminal; The third step: extract the characteristic parameters that characterize the winding state, including: 1) Perform pseudo-color processing on the acquired amplitude-frequency curve to obtain a pseudo-color image and a pixel matrix g(x, y) whose size is 512×512, where x and y are the coordinates of the pixel matrix, and the pixel matrix is as follows; 2) Calculate the image gradient of the pseudo-color image: G _x (x,y)=g(x+1,y)-g(x-1,y) (4) G _y (x,y)=g(x,y+1)-g(x,y-1) (5) Wherein, G _x (x, y) represents the horizontal direction gradient of false color image, G _y (x, y) represents the vertical direction gradient of false color image, g (x, y) is the pixel matrix of color image; 3) Calculate the gradient magnitude and gradient direction of the pixel matrix: Among them, G(x, y) is the gradient magnitude at the pixel point (x, y), and σ(x, y) is the gradient direction at the pixel point (x, y); Step 4: Evaluate the winding condition of the on-board traction transformer, including: 1) Calculate the evaluation factor K of the winding state of the on-board traction transformer: 2) Use the evaluation factor to evaluate the winding state of the vehicle traction transformer: K _h is the evaluation factor when the winding state of the vehicle traction transformer is normal, and K _d is the evaluation factor when the winding state of the vehicle traction transformer is faulty. If 0<T<0.78, it means that the winding state of the vehicle traction transformer is normal. If T≥0.78, it means that the vehicle traction transformer winding state is normal. The winding state of the traction transformer is abnormal or faulty and needs to be repaired or replaced.