CN111398810A - Slip ring electric spark detection and diagnosis system and detection and diagnosis method - Google Patents
Slip ring electric spark detection and diagnosis system and detection and diagnosis method Download PDFInfo
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- CN111398810A CN111398810A CN202010175847.9A CN202010175847A CN111398810A CN 111398810 A CN111398810 A CN 111398810A CN 202010175847 A CN202010175847 A CN 202010175847A CN 111398810 A CN111398810 A CN 111398810A
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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
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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Abstract
The invention discloses a slip ring electric spark detection and diagnosis system and a detection and diagnosis method, which comprise a current transformer module, a current sampling module, a signal conditioning module, an AD conversion module, an MCU module and a communication module; the current flowing through the slip ring is sampled through the current sampling module, the current is converted into a digital signal through the AD conversion module and transmitted to the MCU module to be processed, the MCU module extracts the characteristics of the current signal and judges whether the slip ring generates electric sparks or not by combining with an electric spark characteristic threshold value calculated and processed according to the operating parameters of the double-fed generator set, and the result of data analysis is stored and uploaded. The invention has the following beneficial effects: the invention can detect and diagnose the electric spark generated by the slip ring in real time and carry out early warning, remind maintenance personnel to process in time, effectively reduce the failure of the slip ring caused by the electric spark, reduce the abrasion of the slip ring and provide guarantee for the operation of the slip ring and the whole machine; the expandability is strong, and the application prospect is wide.
Description
Technical Field
The invention relates to the technical field of wind driven generators, in particular to a slip ring electric spark detection and diagnosis system and a detection and diagnosis method which are low in cost, high in reliability and capable of rapidly detecting electric sparks between slip rings and electric brushes in real time.
Background
The slip ring is used as a dynamic-static conversion device, and the generator can be unstable in operation and even shut down due to the faults of the electric brush and the slip ring system. For the units applied to severe conditions such as mountains, oceans and the like, a large amount of manpower and material resources are consumed for maintaining and repairing the electric brush and the slip ring system, and the maintenance and the repair are difficult. One factor that slip rings are prone to failure is the effect of slip ring sparks, which can cause damage to the slip rings and brushes, the accumulation of which can lead to wear of the slip rings and even failure of the entire system. If the device can detect the electric spark in time and perform early warning and timely treatment when the electric spark frequently occurs, the device can effectively prevent and slow down the influence of the electric spark on the slip ring, prevent accidents and save maintenance and repair costs.
The monitoring method of the electric spark between the electric brush and the slip ring comprises a high-frequency disturbance monitoring method of a main pole magnetic field, a radio wave monitoring method, an electric spectrum monitoring method, a photoelectric tube array and optical fiber light beam coupling monitoring method, an excitation voltage monitoring method, an image monitoring method and the like. The existing monitoring system and method for the electric spark between the electric brush and the slip ring generally need to add extra sensor equipment, and are complex in analysis and calculation, high in cost, and poor in reliability and adaptability.
Disclosure of Invention
In order to overcome the defects of the prior art that additional sensor equipment is required to be added, the analysis and calculation are complex, the cost is high, and the reliability and the adaptability are poor, the invention provides the slip ring electric spark detection and diagnosis system and the detection and diagnosis method which have low cost and high reliability and can quickly detect the electric spark between the slip ring and the electric brush in real time.
In order to achieve the purpose, the invention adopts the following technical scheme:
a slip ring electric spark detection and diagnosis system comprises a current transformer module, a current sampling module, a signal conditioning module, an AD conversion module, an MCU module and a communication module; the MCU module is respectively and electrically connected with the communication module and the AD conversion module; the signal conditioning module is respectively and electrically connected with the AD conversion module and the current sampling module, and the current transformer module is electrically connected with the current sampling module.
The current sampling module is used for sampling the current flowing through the slip ring, the current is converted into a digital signal through the AD conversion module and transmitted to the MCU module for processing, the MCU module extracts the characteristics of the current signal and judges whether the slip ring generates electric sparks or not by combining with an electric spark characteristic threshold value calculated and processed according to the operating parameters of the double-fed generator set, and the result of data analysis is stored and uploaded.
Preferably, the communication module comprises a GPIO module, an RS-485 module, a CAN module and a network port module; the GPIO module, the RS-485 module, the CAN module and the network port module are all electrically connected with the MCU module; and various communication interfaces are realized, and system expansion is facilitated.
A detection and diagnosis method of a slip ring electric spark detection and diagnosis system comprises the following steps:
(3-1) sampling the current flowing through the slip ring through the current sampling module to obtain characteristic data;
(3-2) the obtained characteristic data is converted into current data through the signal conditioning module and the AD conversion module and transmitted to the MCU module for processing;
(3-3) after receiving the processed current data, the MCU module calculates and extracts the characteristics of the current data and gives a judgment result of whether electric sparks occur; and if the slip ring is detected to generate the electric spark, storing the data result of the generated electric spark and uploading the data result through the communication module.
Preferably, the specific steps of step (3-3) are as follows:
(4-1) after receiving the processed current data, the MCU module sets a moving window, wherein the moving window comprises m current data and is expressed as { i } ia}＝[i1a,i2a,i3a,...,ima]；
(4-2) performing wavelet decomposition on the m current data to obtain a modulus maximum value point dmaxWherein d ismax＝max(|dj,k|),j＝1,2,3,...,k；
(4-3) calculating a characteristic threshold value T according to the active power P and the reactive power Q of the doubly-fed generator set;
(4-4) comparing the characteristic threshold T with the obtained modulus maximum point dmaxMaking a comparison if dmaxT is less than or equal to the value of T, indicating that no electric spark is generated, the step (4-5) is carried out, if d ismaxIf the time is more than T, indicating that the electric spark occurs, storing the data result of the electric spark, uploading the data result through a communication module, and transferring to the step (4-5);
(4-5) sliding the moving window backwards, and turning to the step (4-2).
Preferably, the calculation formula of the characteristic threshold T is:
T＝Kp*sqrt(P)+Kq*sqrt(Q)+Kc
kp, Kq and Kc are empirical coefficients and are calculated according to data in multiple running processes.
Preferably, the specific steps of step (4-2) are as follows:
(6-1) performing wavelet decomposition on the m current data by using a Mallat algorithm, wherein the decomposition level j is k, and obtaining wavelet coefficients [ d ] of high-frequency detail parts of each decomposition level1,k,d2,k,d3,k,...,dj,k]；
(6-2) comparing the obtained wavelet coefficients of the high-frequency detail part of each decomposition level to obtain a modulus maximum value point dmaxWherein d ismax＝max(|dj,k|),j＝1,2,3,...,k。
Preferably, the signal conditioning module comprises a signal amplifying circuit and a filter circuit; the specific steps of the step (3-2) are as follows:
(7-1) carrying out signal amplification on the obtained characteristic data through a signal amplification circuit, and filtering through a filter circuit;
(7-2) converting the amplified and filtered characteristic data into a digital signal through an AD conversion module;
and (7-3) converting the obtained digital signals into current data through proportion conversion, and transmitting the current data to the MCU module for processing.
Therefore, the invention has the following beneficial effects: the detection method has low cost and high reliability, can detect and diagnose the electric spark generated by the slip ring in real time and carry out early warning, reminds maintenance personnel to carry out treatment in time, can effectively reduce the fault of the slip ring caused by the electric spark, reduces the abrasion of the slip ring, and provides guarantee for the operation of the slip ring and the whole machine; the method of the invention fully utilizes the existing hardware equipment in the double-fed wind power generation system, is convenient to realize, does not need to change the existing running line, and has low upgrading and modifying cost; the invention has strong expandability and wide application prospect.
Drawings
FIG. 1 is a system block diagram of the present invention;
FIG. 2 is a flow chart of the present invention;
FIG. 3 is a graph of the results of an analysis of the present invention.
In the figure: the device comprises a current transformer module 1, a current sampling module 2, a signal conditioning module 3, an AD conversion module 4, an MCU module 5, a communication module 6, a signal amplification circuit 31, a filter circuit 32, a GPIO module 61, an RS-485 module 62, a CAN module 63 and a network port module 64.
Detailed Description
The invention is further described in the following detailed description with reference to the drawings in which:
the embodiment shown in fig. 1 is a slip ring electric spark detection and diagnosis system, which includes a current transformer module 1, a current sampling module 2, a signal conditioning module 3, an AD conversion module 4, an MCU module 5, and a communication module 6; the MCU module is respectively and electrically connected with the communication module and the AD conversion module; the signal conditioning module is respectively and electrically connected with the AD conversion module and the current sampling module, and the current transformer module is electrically connected with the current sampling module.
The communication module comprises a GPIO module 61, an RS-485 module 62, a CAN module 63 and a network port module 64; the GPIO module, the RS-485 module, the CAN module and the network port module are all electrically connected with the MCU module.
The current transformer module: the current transformer is used for realizing the coupling of the current flowing through the slip ring, and the detection system is electrically isolated from the detected system, so that the safety of the detection system and personnel is ensured; the primary side of the current transformer is a lead connected with the slip ring, and the secondary side of the current transformer is connected with the current sampling module; the primary side capacity of the current transformer is selected according to 80% of the maximum current flowing through the slip ring, and the secondary side output is 1A.
A current sampling module: the current sampling module samples by connecting 2 high-precision metal alloy resistors with power of 2W and resistance of 0.075 omega in series, and converts a current signal into a voltage signal; when current sampling is carried out, three-phase current can be simultaneously sampled, and comparison and mutual verification are carried out through current waveforms of the three-phase current when electric sparks occur on the slip ring, so that the accuracy of judging the electric sparks generated on the slip ring is improved; meanwhile, the sampling module has the functions of overcurrent and overvoltage protection.
A signal conditioning module: and the signal conditioning module amplifies the voltage signal obtained by the current sampling module by 60 times to reach the range of +/-9V, and then performs filtering conditioning.
An AD conversion module: the AD conversion module selects a high-speed AD conversion chip with more than 16 bits, converts the conditioned voltage analog signal into a digital signal, and then converts the digital signal into current data through proportion conversion.
The MCU module: the MCU module is responsible for initializing each peripheral system and controlling a service process, and after receiving the AD conversion data, the MCU module calculates and extracts characteristics of the data, and when the slip ring is ignited, the current flowing through the slip ring jumps. The slip ring current sudden change is reflected in two aspects: firstly, the amplitude of the current changes; and secondly, the frequency domain quantity of the frequency domain changes regularly in the period of time. According to a wavelet transformation theory, each frequency range of a signal is taken as a function of time, the time-varying characteristic of the characteristic frequency of the signal is calculated, the change rule of the signal amplitude value in a time domain range is combined, the characteristic threshold value of the electric spark is calculated and processed according to the operation parameters of the double-fed generator set, and whether the spark occurs between the slip ring and the electric brush or not can be diagnosed through characteristic extraction and calculation; if the electric spark is detected, the collected data CAN be stored, and meanwhile, the alarm information CAN be sent to a master control or upper computer through interfaces such as CAN, RS-485, network ports and GPIO.
A communication module: the GPIO module, the RS-485 module, the CAN module and the network port module which interact with other systems CAN report the event of generating the electric spark to an upper computer or a main control system after detecting and diagnosing the electric spark generated by the slip ring.
A detection and diagnosis method of a slip ring electric spark detection and diagnosis system is shown in FIG. 2, and comprises the following steps:
step 100, sampling current flowing through a slip ring through a current sampling module to obtain characteristic data;
200, converting the obtained characteristic data into current data through the processing of a signal conditioning module and an AD conversion module, and transmitting the current data to an MCU module for processing;
step 201, the obtained characteristic data is subjected to signal amplification through a signal amplification circuit and is filtered through a filter circuit;
step 202, the amplified and filtered characteristic data is converted into a digital signal through an AD conversion module;
step 203, converting the obtained digital signals into current data through proportion conversion, and transmitting the current data to the MCU module for processing;
step 300, after receiving the processed current data, the MCU module calculates and extracts the characteristics of the current data and gives a judgment result whether the electric spark occurs; if the slip ring is detected to generate the electric spark, storing a data result of the generated electric spark and uploading the data result through the communication module;
step 301, after receiving the processed current data, the MCU module sets a moving window, where the moving window includes m current data, and is denoted as { i } {a}＝[i1a,i2a,i3a,...,ima]；
The current data can be given by the formula ia＝sn+en+nIs represented by, wherein snFor stationary signals, enIn order to be able to detect the noise signal,nfor generating electric sparksStream mutation signal, the present inventionnCarrying out detection;
step 302, performing wavelet decomposition on the m current data by using a Mallat algorithm, selecting a wavelet function DB4 wavelet, obtaining wavelet coefficients [ d ] of high-frequency detail parts of each decomposition level, wherein the decomposition level j is 41,4,d2,4,d3,4,d4,4]；
Step 303, comparing the obtained wavelet coefficients of the high-frequency detail parts of each decomposition level to obtain a modulus maximum value point dmaxWherein d ismax＝max(|dj,k|),j＝1,2,3,...,k；
Step 304, calculating a characteristic threshold value T by using a formula T ═ Kp · sqrt (P) + Kq · sqrt (Q) + Kc according to the active power P and the reactive power Q of the doubly-fed generator set; kp, Kq and Kc are empirical coefficients and are calculated according to data in multiple running processes;
step 305, comparing the characteristic threshold T with the obtained maximum modulus point dmaxMaking a comparison if dmaxT is less than or equal to the value of T, indicating that no electric spark is generated, go to step 306, if d ismaxIf the value is more than T, indicating that the electric spark occurs, storing the data result of the electric spark, uploading the data result through a communication module, and transferring to the step 306;
step 306, slide the moving window backward, go to step 302.
As shown in fig. 3, the slip ring current is collected and calculated and analyzed; a, B, C in the figure shows the current waveform of three-phase current, the positions encircled by the oval rings obtained by the detection and diagnosis method have slip ring electric sparks, the positions encircled by the three oval rings are consistent, the slip ring electric sparks are shown to occur at the current positions, and the accuracy of judging the electric sparks generated by the slip rings is improved by comparing and mutually verifying the current waveforms of the three-phase current when the electric sparks occur in the slip rings.
It should be understood that this example is for illustrative purposes only and is not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Claims (7)
1. The slip ring electric spark detection and diagnosis system is characterized by comprising a current transformer module (1), a current sampling module (2), a signal conditioning module (3), an AD conversion module (4), an MCU module (5) and a communication module (6); the MCU module is respectively and electrically connected with the communication module and the AD conversion module; the signal conditioning module is respectively and electrically connected with the AD conversion module and the current sampling module, and the current transformer module is electrically connected with the current sampling module.
2. The slip ring electric spark detection diagnostic system as claimed in claim 1, wherein the communication module comprises a GPIO module (61), an RS-485 module (62), a CAN module (63) and a portal module (64); the GPIO module, the RS-485 module, the CAN module and the network port module are all electrically connected with the MCU module.
3. A detection and diagnosis method based on the slip ring electric spark detection and diagnosis system of claim 1, characterized by comprising the steps of:
(3-1) sampling the current flowing through the slip ring through the current sampling module to obtain characteristic data;
(3-2) the obtained characteristic data is converted into current data through the signal conditioning module and the AD conversion module and transmitted to the MCU module for processing;
(3-3) after receiving the processed current data, the MCU module calculates and extracts the characteristics of the current data and gives a judgment result of whether electric sparks occur; and if the slip ring is detected to generate the electric spark, storing the data result of the generated electric spark and uploading the data result through the communication module.
4. The detection and diagnosis method of the slip ring electric spark detection and diagnosis system according to claim 3, wherein the specific steps of the step (3-3) are as follows:
(4-1) the MCU module sets a move after receiving the processed current dataA window, comprising m current data, denoted as { i }, within the moving windowa}＝[i1a,i2a,i3a,...,ima]；
(4-2) performing wavelet decomposition on the m current data to obtain a modulus maximum value point dmaxWherein d ismax＝max(|dj,k|)),j＝1,2,3,...,k；
(4-3) calculating a characteristic threshold value T according to the active power P and the reactive power Q of the doubly-fed generator set;
(4-4) comparing the characteristic threshold T with the obtained modulus maximum point dmaxMaking a comparison if dmaxT is less than or equal to the value of T, indicating that no electric spark is generated, the step (4-5) is carried out, if d ismaxIf the time is more than T, indicating that the electric spark occurs, storing the data result of the electric spark, uploading the data result through a communication module, and transferring to the step (4-5);
(4-5) sliding the moving window backwards, and turning to the step (4-2).
5. The detection and diagnosis method of the slip ring electric spark detection and diagnosis system according to claim 4, wherein the characteristic threshold T is calculated by the formula:
T＝Kp*sqrt(P)+Kq*sqrt(Q)+Kc
kp, Kq and Kc are empirical coefficients and are calculated according to data in multiple running processes.
6. The detection and diagnosis method of the slip ring electric spark detection and diagnosis system according to claim 4, wherein the specific steps of the step (4-2) are as follows:
(6-1) performing wavelet decomposition on the m current data by using a Mallat algorithm, wherein the decomposition level j is k, and obtaining wavelet coefficients [ d ] of high-frequency detail parts of each decomposition level1,k,d2,k,d3,k,...,dj,k]；
(6-2) comparing the obtained wavelet coefficients of the high-frequency detail part of each decomposition level to obtain a modulus maximum value point dmaxWherein d ismax＝max(|dj,k|)),j＝1,2,3,...,k。
7. The detection diagnosis method of the slip ring electric spark detection diagnosis system according to claim 3, 4, 5 or 6, wherein the signal conditioning module comprises a signal amplification circuit (31) and a filter circuit (32); the specific steps of the step (3-2) are as follows:
(7-1) carrying out signal amplification on the obtained characteristic data through a signal amplification circuit, and filtering through a filter circuit;
(7-2) converting the amplified and filtered characteristic data into a digital signal through an AD conversion module;
and (7-3) converting the obtained digital signals into current data through proportion conversion, and transmitting the current data to the MCU module for processing.
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Cited By (1)
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Application publication date: 20200710 |