CN110837046B - Converter switching tube fault detection and diagnosis method based on mechanical vibration signals - Google Patents
Converter switching tube fault detection and diagnosis method based on mechanical vibration signals Download PDFInfo
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Abstract
The invention discloses a converter switching tube fault detection and diagnosis method based on mechanical vibration signals, which comprises two links of fault detection and fault diagnosis; a fault detection link acquires a vibration signal of the generator; carrying out envelope spectrum analysis on the acquired vibration signals to obtain an envelope spectrum; calculating first-order and second-order characteristic frequencies of the vibration signals; determining amplitudes corresponding to the first-order characteristic frequency and the second-order characteristic frequency according to the envelope spectrum, comparing the amplitudes with a first-order threshold value and a second-order threshold value respectively, and judging whether the converter switching tube fails or not; extracting the phase of the first-order characteristic frequency component in a fault diagnosis link; and comparing the phase of the first-order characteristic frequency component with the fault positioning information of the switching tube to finish diagnosis. The invention avoids the distortion problem generated by directly calculating the current phase by the fault current and improves the reliability of diagnosis.
Description
Technical Field
The invention belongs to the technical field of power generation, and particularly relates to a converter switching tube fault detection and diagnosis method based on a mechanical vibration signal.
Background
In the case of high-load and overload operation, the power switch tube is the weakest part in the converter, and the investigation shows that the fault rate of the switch tube in the wind power generation system reaches 38%. Therefore, the switching tube with faults can be quickly and accurately diagnosed, isolated and subjected to fault-tolerant control, and the method plays an important role in the operation stability of the whole system. The fault state of the power switch tube can be divided into three types of open-circuit fault, short-circuit fault and intermittent gate signal fault, and the detection and diagnosis of the open-circuit fault are the most critical because the latter two faults can be converted into the open-circuit fault through isolation.
At present, fault diagnosis of a switch tube of a converter is mostly based on an electrical signal and cannot be decoupled with a control system, so that the fault diagnosis is easily influenced by a control strategy and cannot be applied to certain occasions where current/voltage sensors cannot be installed. Since the vibration of the permanent magnet synchronous motor controlled by the converter on the mechanical structure is caused by the fault of the converter switching tube, the fault diagnosis by using a mechanical vibration signal can be considered. However, at present, fault diagnosis based on vibration signals is only used for diagnosing electromechanical faults, such as gear faults, shaft faults, bearing faults and motor faults, and no method for diagnosing faults of a switching tube of a converter of a permanent magnet synchronous power generation system by using vibration signals exists.
Disclosure of Invention
The invention aims to provide a fault detection and diagnosis method for a switching tube of a current transformer based on a mechanical vibration signal.
The technical solution for realizing the purpose of the invention is as follows: a converter switch tube fault detection and diagnosis method based on mechanical vibration signals comprises two links of fault detection and fault diagnosis;
(1) the fault detection link comprises the following specific steps:
step 1, collecting a vibration signal of a generator;
step 2, carrying out envelope spectrum analysis on the collected vibration signals to obtain an envelope spectrum;
step 3, calculating first-order and second-order characteristic frequencies of the vibration signals;
step 4, determining amplitude values corresponding to the first-order characteristic frequency and the second-order characteristic frequency according to the envelope spectrum, comparing the amplitude values with a first-order threshold value and a second-order threshold value respectively, and judging whether the converter switching tube has faults or not;
(2) the fault diagnosis link comprises the following specific steps:
step 1, extracting the phase of a first-order characteristic frequency component;
and 2, comparing the phase of the first-order characteristic frequency component with fault positioning information of the switching tube to finish diagnosis.
Compared with the prior art, the invention has the following remarkable advantages: 1) the vibration signal of the generator is used as a fault diagnosis signal, is completely independent from a converter system, cannot interfere with the converter system, ensures the stability of system operation, and is suitable for a working environment in which strong interference such as a current/voltage sensor cannot be installed; 2) the current phase signal obtained by calculating the mechanical phase signal of the photoelectric encoder is used for positioning the fault, so that the problem of distortion caused by directly calculating the current phase by the fault current is avoided, and the reliability of diagnosis is improved.
Drawings
Fig. 1 is a structural diagram of a permanent magnet synchronous power generation system.
Fig. 2 is a schematic view of a mounting position of the vibration sensor.
Fig. 3 is a flow chart of a method for detecting and diagnosing faults of a switching tube of a converter.
Fig. 4 is a characteristic diagram of the envelope spectrum of the vibration signal under different open circuit faults of the current transformer.
Fig. 5 is a schematic diagram of the diagnosis of the open circuit fault of the S3 tube according to the present invention.
Detailed Description
The scheme of the invention is further explained by combining the attached drawings and the specific embodiment.
The invention relates to a converter topology of a permanent magnet synchronous power generation system, which is shown in figure 1 and belongs to a voltage type three-phase six-switch rectifier. The vibration sensor for detecting the mechanical vibration signal is installed above the bearing at the driving end of the permanent magnet synchronous generator, as shown in fig. 2. Fig. 3 shows a method for detecting and diagnosing faults of a switching tube of a current transformer based on a mechanical vibration signal, which includes the following specific contents:
(1) the fault detection link comprises the following specific steps:
step 1, collecting a vibration signal of a generator by using a vibration sensor arranged above a bearing at the driving end of a permanent magnet synchronous generator;
step 2, carrying out envelope spectrum analysis on the collected vibration signals to obtain an envelope spectrum;
firstly, screening vibration signals, and only reserving peak points of the signals, namely points larger than adjacent elements; then, carrying out fast Fourier transform on the peak point curve to obtain a complex number corresponding to each frequency; and finally, drawing a curve by taking the frequency as an abscissa and taking the modular length of the complex number as an ordinate to obtain an envelope spectrum.
Step 3, calculating first-order and second-order characteristic frequencies of the vibration signals;
the calculation formula is as follows:
the first-order characteristic frequency is pole pair number multiplied by the rotation frequency of the motor;
the second-order characteristic frequency is 2 × pole pair number × motor rotation frequency.
Step 4, determining amplitude values corresponding to the first-order characteristic frequency and the second-order characteristic frequency according to the envelope spectrum, comparing the amplitude values with a first-order threshold value and a second-order threshold value respectively, and judging whether the converter switching tube has faults or not;
finding amplitudes corresponding to the first-order characteristic frequency and the second-order characteristic frequency in the envelope spectrum, comparing the amplitudes with a first-order threshold value and a second-order threshold value, if the amplitude of the first-order characteristic frequency is greater than the first-order threshold value and the amplitude of the second-order characteristic frequency is greater than the second-order threshold value, judging that a fault occurs, and entering a fault diagnosis link; otherwise, judging that no fault occurs, and continuing to monitor. The first-order threshold range is 0.05-0.12, and the second-order threshold range is 0.03-0.07.
(2) The fault diagnosis link comprises the following specific steps:
step 1, extracting the phase of the first-order characteristic frequency component, wherein a specific calculation formula is as follows:
wherein arctan () is an arctan function, x is the real part of the first order eigenfrequency, and y is the imaginary part of the first order eigenfrequency;
and 2, comparing the phase of the first-order characteristic frequency component with fault positioning information of the switching tube to finish diagnosis.
TABLE 1 switching tube Fault location information Table
Examples
To verify the validity of the inventive scheme, the following simulation experiment was performed.
The motor is a 4-pole-pair permanent magnet synchronous motor, the rotating speed of the motor is set to be 1.6Hz, the envelope spectrum of vibration signals of the converter under different open-circuit faults is shown in figure 4, and the length of the vibration signals is the vibration signals of the permanent magnet synchronous generator rotating for two circles (720 degrees) under the frequency of 1.6 Hz. The threshold value of the first-order characteristic frequency is set to be 0.1, the second-order characteristic frequency is set to be 0.05, and the method is utilized to detect and diagnose the fault.
(1) Fault detection
For normal conditions, no fault is generated because the amplitude of the first-order characteristic frequency is judged not to exceed the threshold value of 0.1; for the S3 fault, the first-order characteristic frequency amplitude is 0.16 and exceeds the threshold value of 0.1, the second-order characteristic frequency amplitude is 0.1 and exceeds the threshold value of 0.05, and therefore the fault is judged to occur; for the S5 fault, the first-order characteristic frequency amplitude is 0.14 and exceeds a 0.1 threshold, the second-order characteristic frequency amplitude is 0.1 and exceeds a 0.05 threshold, and therefore the fault is judged to occur; for the S6 fault, since the first-order characteristic frequency amplitude is 0.16 and exceeds the threshold of 0.1, and the second-order characteristic frequency amplitude is 0.1 and exceeds the threshold of 0.05, the fault is determined to occur. The detection method is simple and effective, and the detection conclusion is completely consistent with the actual situation.
(2) Fault diagnosis
The open-circuit fault condition of the S3 tube is further diagnosed, and the diagnosis method in other conditions is analogized. The fault detection link determines that S3 has a fault, the first-order characteristic frequency of the fault is corresponding to a complex number (-30.38+32.52i), and a phase (arctan (32.52/-30.38) + pi (133 °) is obtained according to a phase calculation formula, as shown in fig. 3. According to table 1, since 133 ° is 90 ° to 150 °, it is determined that the S3 tube has failed, and the diagnosis is completed. The diagnosis method is simple and effective, and the diagnosis conclusion is completely consistent with the actual situation.
Claims (7)
1. The method for detecting and diagnosing the fault of the switching tube of the converter based on the mechanical vibration signal is characterized by comprising two links of fault detection and fault diagnosis;
(1) the fault detection link comprises the following specific steps:
step 1, collecting a vibration signal of a generator;
step 2, carrying out envelope spectrum analysis on the collected vibration signals to obtain an envelope spectrum;
step 3, calculating first-order and second-order characteristic frequencies of the vibration signals;
step 4, determining amplitude values corresponding to the first-order characteristic frequency and the second-order characteristic frequency according to the envelope spectrum, comparing the amplitude values with a first-order threshold value and a second-order threshold value respectively, and judging whether the converter switching tube has faults or not;
(2) the fault diagnosis link comprises the following specific steps:
step 1, extracting the phase of a first-order characteristic frequency component;
step 2, comparing the phase of the first-order characteristic frequency component with fault positioning information of the switching tube to finish diagnosis;
the fault location of the switching tube is specifically as follows: when the phase is between-90 degrees and-150 degrees, the switching tube S1 is judged to have a fault; when the phase is between-150 degrees and-180 degrees or between 150 degrees and 180 degrees, the switching tube S2 is judged to have a fault; when the phase is at 90-150 degrees, judging that the switching tube S3 has a fault; when the phase is 30-90 degrees, judging that the switching tube S4 has a fault; when the phase is at-30 degrees to-30 degrees, the switching tube S5 is judged to have a fault; when the phase is between-30 degrees and-90 degrees, the switching tube S6 is judged to have a fault; wherein s1-s6 are six switching tubes of the voltage type three-phase six-switch rectifier.
2. The method for detecting and diagnosing the fault of the converter switching tube based on the mechanical vibration signal as claimed in claim 1, wherein in the step 1 of the fault detection step, a vibration sensor installed above a bearing at the driving end of the permanent magnet synchronous generator is used for acquiring the vibration signal of the generator.
3. The method for detecting and diagnosing the fault of the switching tube of the current transformer based on the mechanical vibration signal as claimed in claim 1, wherein in the step 2 of the fault detection link, the vibration signal is firstly screened, and only the peak point of the signal, namely the point larger than the adjacent elements, is reserved; then, carrying out fast Fourier transform on the peak point curve to obtain a complex number corresponding to each frequency; and finally, drawing a curve by taking the frequency as an abscissa and the modular length of the complex number as an ordinate, and obtaining the envelope spectrum.
4. The method for detecting and diagnosing the fault of the switching tube of the converter based on the mechanical vibration signal as claimed in claim 1, wherein in the step 3 of the fault detection link, the calculation formula of the first-order and second-order characteristic frequencies of the vibration signal is as follows: the first-order characteristic frequency is pole pair number multiplied by the rotation frequency of the motor; the second-order characteristic frequency is 2 × pole pair number × motor rotation frequency.
5. The method for detecting and diagnosing the fault of the switching tube of the converter based on the mechanical vibration signal as claimed in claim 1, wherein in the step 4 of the fault detection link, the amplitudes corresponding to the first-order characteristic frequency and the second-order characteristic frequency are found in the envelope spectrum and are compared with a first-order threshold and a second-order threshold, if the amplitude of the first-order characteristic frequency is greater than the first-order threshold and the amplitude of the second-order characteristic frequency is greater than the second-order threshold, the fault is determined to occur, and the fault diagnosis link is entered; otherwise, judging that no fault occurs, and continuing to monitor.
6. The method for detecting and diagnosing faults of the switching tubes of the converter based on the mechanical vibration signals as claimed in claim 1, wherein in the step 4 of the fault detection link, the first-order threshold value ranges from 0.05 to 0.12, and the second-order threshold value ranges from 0.03 to 0.07.
7. The method for detecting and diagnosing the fault of the switching tube of the converter based on the mechanical vibration signal as claimed in claim 1, wherein in the step 1 of the fault diagnosis step, the calculation formula of the phase corresponding to the first-order characteristic frequency is as follows:
where arctan () is an arctan function, x is the real part of the first order eigenfrequency, and y is the imaginary part of the first order eigenfrequency.
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| CN112649758B (en) * | 2021-01-19 | 2022-08-16 | 易事特集团股份有限公司 | Open-circuit fault detection method and device and computer equipment |
| CN113565484B (en) * | 2021-07-23 | 2022-06-07 | 西安交通大学 | Fracturing pump valve fault diagnosis method based on relative root mean square value |
| CN115824647B (en) * | 2023-02-16 | 2023-05-12 | 南京凯奥思数据技术有限公司 | Bearing fault diagnosis method and diagnosis equipment based on mean square error time domain downsampling |
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