A method and system for measuring a ground fault of a generator stator bar

Abstract

The application discloses a kind of method and system for measuring generator stator bar ground fault, including, adjustable DC voltage is obtained according to input device voltage, and according to preset frequency and current, closed loop loop including variable frequency constant current source board is established, so as to obtain controllable output current;According to controllable output current, the current of stator bar ground end is obtained by combining wireless flexible current clamp;Stator bar ground end current is transmitted to intelligent terminal for display, and fault judgment is carried out in combination with fault detection logic.The method is simple, no high voltage is generated, the output current is controllable, and there is no harm to equipment and personnel, and the technical level of operating personnel is not high.

Description

Technical Field

[0001] This invention relates to the field of generator stator bar grounding fault detection technology, and in particular to a method and system for measuring generator stator bar grounding faults. Background Technology

[0002] Currently, there are three main methods for detecting grounding faults in generator stator bars: one is to pass a large current through the grounding point of the bar to cause the fault point to burn and spark, and then visually determine the fault point. This method is inefficient because the current is uncontrollable and relatively crude, and it will cause irreversible damage to the generator stator, expand the damaged area of ​​the stator, and cause greater losses. If the grounding fault occurs in the lower layer of bars in the slot, this method is difficult to find the location of the faulty bar.

[0003] The second method is manual voltage regulation, which uses a voltage regulator to control the voltage from 0 to 250V, and then connects to a two-stage step-up transformer to generate a current of 0-5A at the fault location on the secondary side of the transformer. However, this method involves complex equipment, including air switches for input protection, voltage regulators and voltage measuring instruments, step-up transformers and grounding current measuring instruments, high-voltage current output limiting equipment, etc. The equipment is bulky, the wiring is complex, and the output voltage may be as high as 12KV. It requires a high level of technical skill from on-site operators and poses certain safety risks.

[0004] Third, many power plants now use a small current method to locate ground faults. This involves injecting a small current into the faulty phase, measuring the current value of each branch using a clamp meter to determine the faulty branch, and then measuring the current value of each conductor within the faulty branch to determine the faulty conductor. While this method is simpler and has lower safety risks compared to traditional methods such as segmented isolation insulation testing, voltage observation, manual excitation and monitoring of the main circuit current direction, open transformer method, and current-voltage method, it requires a combination of instruments to output a small current. If this current becomes uncontrollable, the grounding current through the fault point may damage the stator core. For large and medium-sized generators with many branches and conductors, especially large generators with branches connected in parallel at both ends of the faulty phase, this method is not very accurate due to the inability to eliminate external interference during measurement. It requires simultaneous measurement and recording, and repeated measurements are necessary due to significant interference, followed by data analysis. In reality, this method is not very efficient. Furthermore, careless operation during the combination of instruments may leave metal objects such as terminals, bolts, and gaskets inside the generator, causing even more serious safety hazards. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the aforementioned existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a method and system for measuring grounding faults in generator stator bars, which can solve the problems mentioned in the background art.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for measuring grounding faults in generator stator bars, comprising:

[0009] The adjustable DC voltage is obtained based on the input device voltage, and a closed loop including the frequency converter constant current source board is established based on the preset frequency and current to obtain the controllable output current.

[0010] Based on the controllable output current, the stator bar grounding terminal current is obtained in conjunction with the wireless flexible current clamp.

[0011] The current at the grounding end of the stator bar is transmitted to the intelligent terminal for display, and fault judgment is performed in conjunction with the fault detection logic.

[0012] As a preferred embodiment of the method for measuring generator stator bar grounding faults according to the present invention, it further includes:

[0013] Check the visible parts of the generator stator winding for any abnormalities. If any abnormalities are found, address the abnormal parts.

[0014] If no abnormality is found, disconnect the generator outlet and neutral point, and use an insulation resistance meter to find the ground fault phase of the generator stator bar;

[0015] Connect the current output line in the measurement method to the faulty phase at the generator outlet;

[0016] The controllable current is adjusted and output to the fault phase on the generator outlet side by means of the integrated digital programmable intelligent display terminal control buttons in the measurement method;

[0017] Using wireless current clamps to simultaneously clamp onto the branch of the faulty phase, the real-time current display values ​​of different branches of the integrated digital programmable intelligent display terminal are obtained, and the faulty branch is determined by the current magnitude.

[0018] At the upper end of the stator winding, starting from the faulty branch near the generator outlet, clamp at least one wireless current clamp every fixed number of stator bars according to the stator bar structure, obtain the real-time current display value of the branch of the integrated digital programmable intelligent display terminal, and determine the location of the faulty bar by the current magnitude.

[0019] A system for measuring grounding faults in generator stator conductors, characterized in that it includes a display terminal unit, a digital control unit, a frequency converter unit, a power supply unit, a voltage and current sampling unit, and a measurement unit.

[0020] The display terminal unit is used to provide an intuitive human-machine interface, obtain the calculation results of the digital control unit, centrally display the measured current of different branches, and control the lower-level machine to control, measure, protect and exchange data for the whole machine.

[0021] The digital control unit is used to generate and output a variable frequency and adjustable amplitude sinusoidal AC waveform signal through a microcontroller program to the variable frequency constant current source board for amplification and output, exchange data with the host computer, perform calculations based on the data obtained by the measurement unit, and display the calculation results on the display terminal unit.

[0022] The frequency converter unit is used to receive the sinusoidal signal sent by the digital control unit, amplify it in a controllable manner, and output the target controllable current.

[0023] The power supply unit is used to provide power to the whole machine, provide DC power to the frequency converter unit, and provide power to the display terminal unit and the digital control unit.

[0024] The voltage and current sampling unit is used to measure the output current and feedback voltage and convert them into digital signals to provide to the digital control unit for calculation.

[0025] The measurement unit is used to measure the stator bar grounding current and transmit the test results wirelessly to the digital control unit.

[0026] As a preferred embodiment of the method and system for measuring grounding faults in generator stator bars according to the present invention, the power supply unit includes a rectifier and filter module, a voltage regulator module, and an auxiliary power supply module.

[0027] When the system is working, the voltage regulator module provides DC power to the frequency converter unit, the auxiliary power module provides a fixed DC voltage to the display terminal unit and the digital control unit, and the rectifier and filter module provides low-interference and low-ripple power to the voltage regulator module and the auxiliary power module.

[0028] When the frequency converter receives the sinusoidal signal from the digital control unit, the frequency converter provides an AC current signal with a preset frequency and current to the generator stator bars.

[0029] When a ground current is generated at the grounding end of the stator bar, the ground current is measured by a multi-channel wireless flexible current clamp held on the stator bar at different positions and transmitted wirelessly to the display terminal unit for display. The ground current data is also transmitted to the control unit for logical judgment and calculation.

[0030] When the grounding current data result is determined, the determination result is mapped and displayed with the input grounding current data, and the mapping result is transmitted to the display terminal unit to refresh the display content.

[0031] As a preferred embodiment of the method and system for measuring grounding faults of generator stator bars according to the present invention, the control unit includes a start-stop control module, a data receiving and sending module, and a data processing module. The start-stop control module receives start-stop control commands sent by the display terminal unit.

[0032] When the system is working, the user sends a start command through the display terminal unit. After the start / stop control module receives the start command, the control unit performs the operation, and the user obtains the grounding current through the measurement unit.

[0033] Before the user obtains the grounding current through the measurement unit for measurement, check whether there is any abnormality in the visible part of the generator stator winding. If there is any abnormality, deal with the abnormal part.

[0034] If no abnormality is found, disconnect the generator outlet and neutral point, and use an insulation resistance meter to find the ground fault phase of the generator stator bar;

[0035] Connect the current output line on the system to the faulty phase at the generator outlet, and adjust and output a controllable current to the faulty phase at the generator outlet side through the control buttons on the system's display terminal unit.

[0036] Using N wireless current clamps simultaneously clamped onto N branches of the faulty phase, observe the N real-time current display values ​​on the display terminal unit, and determine the faulty branch by inputting the current into the data processing module, where N is the number of faulty phase branches.

[0037] As a preferred embodiment of the method and system for measuring generator stator bar grounding faults according to the present invention, the data processing module includes a first logical judgment, a second logical judgment, and a third logical judgment.

[0038] The first logical judgment includes the following: when all parallel branches of the generator stator bar ground fault phase near the neutral point can be disconnected, and the current display of the 1st, 2nd, ..., ith, ... Nth channels in the display terminal unit is 0, and the current display value of the ith channel is the controllable current value output by the test instrument, then the fault branch is the ith branch;

[0039] When the generator neutral point single phase is connected in parallel with odd-numbered branches and even-numbered branches, and the three phases are connected in a star structure through flexible connections and / or copper busbars, disconnect the flexible connection and / or copper busbar of the faulty phase near the neutral point and observe the changes in the current values ​​of the N channels in the display terminal unit. If the current value of the i-th branch is larger than the current values ​​of the other branches, then the faulty branch is the i-th branch.

[0040] As a preferred embodiment of the method and system for measuring generator stator bar grounding faults according to the present invention, the second logical judgment includes:

[0041] At the upper end of the stator winding, starting from the fault branch near the generator outlet side, a measuring unit is placed every k wires to obtain the N real-time current display values ​​of the display terminal unit.

[0042] If I is present in the obtained current i >I 1， I i >I 2， ..., I i >I N , that is I i For I N If the maximum value is found, the faulty bar is determined to be between (i-1)*k and i*k.

[0043] When the faulty bar is determined to be between (i-1)*k and i*k, a measuring unit is placed at the lower end of the stator winding on each of the (i-1)*k to i*k bars of the i-th branch. The real-time current display value of the k-channel display terminal unit is obtained again. At this time, the k-channel current display is within the mapping range of the i-th branch. The magnitude of the real-time current of the k-channel is determined.

[0044] If the current of all k-1 bars except the m-th bar is equal in the real-time current of the k-path, and the real-time current value of the m-th bar is less than the current of the other k-1 bars, then the faulty bar is determined to be between the m-1 bar and the m+1 bar.

[0045] As a preferred embodiment of the method and system for measuring generator stator bar grounding faults according to the present invention, the third logical judgment includes:

[0046] When m is an odd number, a measuring unit is placed on the i-th branch, the m-th bar, and the (m+1)-th bar to obtain the real-time current display values ​​of the two bars of the display terminal unit.

[0047] If I m root bar current and I m+1 If the currents of the bars are equal, then the faulty bar is located in the (m+1)th slot.

[0048] When m is even, a measuring unit is placed on the i-th branch, the (m-1)-th bar, and the m-th bar to obtain the real-time current display values ​​of the two bars of the display terminal unit.

[0049] If I m-1 root bar current and I m If the currents of the bars are equal, then the faulty bar is located in the m-th slot.

[0050] A computer device includes a memory and a processor, the memory storing a computer program, characterized in that the processor executes the computer program to implement the steps of the method described above.

[0051] A computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of the method described above.

[0052] The beneficial effects of this invention are as follows: This invention proposes a method and system for measuring grounding faults in generator stator windings. All operations are performed on an integrated digital programmable intelligent display terminal. Frequency conversion is used to mitigate the impact of potential interference sources on the measurement. This device can simultaneously measure multiple branches or multiple windings of the faulty phase in the generator stator winding using multiple measurement units, achieving high measurement accuracy. The integrated digital programmable intelligent display terminal centrally displays the real-time measurement values ​​of each wireless current clamp, enabling intuitive and rapid identification of the faulty winding, effectively shortening the time required to locate grounding faults. This method features simple wiring, no high-voltage generation, controllable output current, poses no harm to equipment or personnel, and does not require a high level of operator skill. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0054] Figure 1 A flowchart of a method and system for measuring grounding faults in generator stator bars, provided as an embodiment of the present invention;

[0055] Figure 2 A schematic diagram of a method and system for measuring grounding faults in generator stator bars, provided as an embodiment of the present invention;

[0056] Figure 3 This is an internal structural diagram of a computer device for a method and system for measuring grounding faults in generator stator bars, provided as an embodiment of the present invention. Detailed Implementation

[0057] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0058] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0059] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0060] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0061] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0062] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0063] Example 1

[0064] Reference Figure 1-3 This is the first embodiment of the present invention, which provides a method and system for measuring ground faults in generator stator bars, comprising:

[0065] The adjustable DC voltage is obtained based on the input device voltage, and a closed loop including the frequency converter constant current source board is established based on the preset frequency and current to obtain the controllable output current.

[0066] Furthermore, based on the controllable output current, the stator bar grounding terminal current is obtained by combining it with a wireless flexible current clamp.

[0067] Furthermore, the current at the grounding end of the stator bar is transmitted to the intelligent terminal for display, and fault diagnosis is performed in conjunction with fault detection logic.

[0068] Specifically, check the visible parts of the generator stator winding for any abnormalities. If any abnormalities are found, address the abnormal parts.

[0069] Furthermore, if no abnormality is found, disconnect the generator outlet and neutral point, and use an insulation resistance meter to find the ground fault phase of the generator stator bar.

[0070] Furthermore, the current output line in the measurement method is connected to the faulty phase at the generator outlet;

[0071] Furthermore, the controllable current is adjusted and output to the fault phase on the generator outlet side by means of the control buttons of the integrated digital programmable intelligent display terminal in the measurement method;

[0072] Furthermore, wireless current clamps are used to simultaneously clamp onto the branch of the faulty phase to obtain the real-time current display values ​​of different branches of the integrated digital programmable intelligent display terminal, and the faulty branch is determined by the current magnitude.

[0073] It should be noted that, at the upper end of the stator winding, starting from the faulty branch near the generator outlet, at least one wireless current clamp is clamped every fixed number of stator bars according to the stator bar structure to obtain the real-time current display value of the branch of the integrated digital programmable intelligent display terminal, and the location of the faulty bar is determined by the magnitude of the current.

[0074] In one embodiment, a system for measuring ground faults in generator stator bars includes a display terminal unit 100, a digital control unit 200, a frequency converter unit 300, a power supply unit 400, a voltage and current sampling unit 500, and a measurement unit 600.

[0075] The display terminal unit 100 is used to provide an intuitive human-machine interface, obtain the calculation results of the digital control unit 200, centrally display the measured current of different branches, and control the lower-level machine to control, measure, protect and exchange data for the whole machine.

[0076] The digital control unit 200 is used to generate and output a variable frequency and adjustable amplitude sinusoidal AC waveform signal through a microcontroller program to the variable frequency constant current source board for amplification and output, exchange data with the host computer, perform calculations based on the data obtained by the measurement unit 600, and display the calculation results on the display terminal unit 100.

[0077] The frequency converter 300 is used to receive the sinusoidal signal sent by the digital control unit 200, amplify it in a controllable manner, and output the target controllable current.

[0078] The power supply unit 400 is used to provide power to the whole machine, provide DC power to the frequency converter unit 300, and provide power to the display terminal unit 100 and the digital control unit 200.

[0079] The voltage and current sampling unit 500 is used to measure the output current and feedback voltage and convert them into digital signals to provide to the digital control unit 200 for calculation.

[0080] The measurement unit 600 is used to measure the stator bar grounding current and transmit the test results wirelessly to the digital control unit 200.

[0081] The power supply unit 400 includes a rectifier and filter module 401, a voltage regulator module 402, and an auxiliary power supply module 403. When the system is working, the voltage regulator module 402 provides DC power to the frequency converter unit 300, the auxiliary power supply module 403 provides a fixed DC voltage to the display terminal unit 100 and the digital control unit 200, and the rectifier and filter module 401 provides a low-interference, low-ripple power supply to the voltage regulator module 402 and the auxiliary power supply module 403.

[0082] Furthermore, when the frequency converter 300 receives a sinusoidal signal from the digital control unit 200, the frequency converter 300 provides an AC current signal with a preset frequency and current to the generator stator bars.

[0083] Furthermore, when a ground current is generated at the grounding end of the stator bar, the ground current is measured by a multi-channel wireless flexible current clamp held on the stator bar at different positions and transmitted wirelessly to the display terminal unit 100 for display. The ground current data is also transmitted to the word control unit 200 for logical judgment and calculation.

[0084] Furthermore, when the grounding current data result is determined, the determination result is mapped and displayed with the input grounding current data, and the mapping result is transmitted to the display terminal unit 100 to refresh the display content.

[0085] It should be noted that the control unit 200 includes a start-stop control module 201, a data receiving and sending module 202, and a data processing module 303. The start-stop control module 201 receives start-stop control commands sent by the display terminal unit 100.

[0086] Furthermore, when the system is working, the user sends a start command through the display terminal unit 100. After the start / stop control module 201 receives the start command, the control unit 200 performs the operation, and the user obtains the grounding current through the measurement unit 600.

[0087] Furthermore, before the user obtains the grounding current through the measurement unit 600 for measurement, check whether there is any abnormality in the visible part of the generator stator winding. If there is any abnormality, then deal with the abnormal part.

[0088] Furthermore, if no abnormality is found, disconnect the generator outlet and neutral point, and use an insulation resistance meter to find the ground fault phase of the generator stator bar.

[0089] Furthermore, the current output line on the system is connected to the faulty phase at the generator outlet, and the controllable current is adjusted and output to the faulty phase at the generator outlet side through the control buttons of the system's display terminal unit 100.

[0090] Furthermore, N wireless current clamps are used to simultaneously clamp onto N branches of the faulty phase, and the real-time current display values ​​of the 100N channels of the terminal unit are observed. The faulty branch is determined by the current input data processing module 303, where N is the number of branches of the faulty phase.

[0091] The measurement unit 600 can be a wireless current clamp.

[0092] It should be noted that the data processing module 303 includes a first logical judgment, a second logical judgment, and a third logical judgment.

[0093] Furthermore, the first logical judgment includes the following: when all parallel branches of the generator stator bar ground fault phase near the neutral point can be disconnected, and the current display of the 1st, 2nd, ..., ith, ... Nth channels in the display terminal unit 100 is 0, and the current display value of the ith channel is the controllable current value output by the test instrument, then the fault branch is the ith branch.

[0094] Furthermore, when the generator neutral point single phase is connected in parallel with odd-numbered branches and even-numbered branches, and the three phases are connected in a star structure through flexible connections and / or copper busbars, the flexible connection and / or copper busbar of the faulty phase near the neutral point is disconnected, and the changes in the current values ​​of the N channels in the display terminal unit 100 are observed. If the current value of the i-th branch is greater than the current values ​​of the other branches, then the faulty branch is the i-th branch.

[0095] It should be noted that the second logical judgment includes, at the upper end of the stator winding, starting from the fault branch near the generator outlet side, placing a measuring unit 600 every k wire bars to obtain the N-channel real-time current display values ​​of the display terminal unit 100.

[0096] Furthermore, if the acquired current contains I... i >I 1， I i >I 2， ..., I i >I N , that is I i For I N If the maximum value is found, the faulty bar is determined to be between (i-1)*k and i*k.

[0097] Furthermore, when the faulty bar is determined to be between (i-1)*k and i*k, a measuring unit 600 is placed at the lower end of the stator winding on each of the (i-1)*k to i*k bars of the i-th branch, and the k-channel real-time current display value of the display terminal unit 100 is obtained again. At this time, the k-channel current display is within the mapping range of the i-th branch, and the magnitude of the k-channel real-time current is determined.

[0098] It should be noted that if the current of all k-1 bars except the m-th bar is equal in the real-time current of the k-path, and the real-time current value of the m-th bar is less than the current of the other k-1 bars, then the faulty bar is determined to be between the m-1 bar and the m+1 bar.

[0099] It should be noted that the third logical judgment includes, when m is an odd number, placing a measuring unit 600 on the i-th branch, the m-th bar, and the (m+1)-th bar to obtain the real-time current display values ​​of the two bars of the display terminal unit 100.

[0100] Furthermore, if I m root bar current and I m+1 If the currents of the bars are equal, then the faulty bar is located in the (m+1)th slot.

[0101] Furthermore, when m is an even number, a measuring unit 600 is placed on the i-th branch, the (m-1)-th bar, and the m-th bar to obtain the real-time current display value of the two bars of the display terminal unit 100.

[0102] Furthermore, if I m-1 root bar current and I m If the currents of the bars are equal, then the faulty bar is located in the m-th slot.

[0103] The above-mentioned unit modules can be embedded in the processor of the computer device in hardware form or independent of it, or they can be stored in the memory of the computer device in software form, so that the processor can call and execute the corresponding operations of the above modules.

[0104] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 3 As shown, the computer device includes a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a method for measuring grounding faults in generator stator bars. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device casing, or an external keyboard, touchpad, or mouse.

[0105] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0106] The adjustable DC voltage is obtained based on the input device voltage, and a closed loop including the frequency converter constant current source board is established based on the preset frequency and current to obtain the controllable output current.

[0107] Based on the controllable output current, the stator bar grounding terminal current is obtained in combination with the wireless flexible current clamp.

[0108] The stator bar grounding terminal current is transmitted to the intelligent terminal for display, and fault diagnosis is performed in conjunction with fault detection logic.

[0109] Example 2

[0110] Reference Figure 1-3 As an embodiment of the present invention, a method and system for measuring grounding faults in generator stator bars are provided. To verify the beneficial effects of the present invention, a comparative experiment is conducted for scientific demonstration.

[0111] Taking the grounding of the conductor in slot 6 of branch 2 of a certain phase of a generator as an example, the test wiring diagram is attached. Figure 2 :

[0112] When the equipment is working, the 220V AC power input to the device is converted into an adjustable DC voltage of ±15~24V with low ripple coefficient through the main power supply module. This voltage provides the working voltage for the frequency converter constant current source board. At this time, the digital MCU main control board can output a controllable sinusoidal small signal to the frequency converter constant current source board for amplification based on the AC current signal with a frequency of 45~55Hz and a current of 0~5A set by the operator. The amplified signal is measured in real time by the current and voltage sampling module. The measured signal is returned to the CPU board to form a closed loop to achieve the purpose of controllable current output. The output current reaches the generator stator winding through the current output interface, generating a ground current at the stator bar grounding end. The ground current is measured by multiple wireless flexible current clamps clamped on stator bars at different positions and transmitted wirelessly to the host and centrally displayed through an integrated intelligent terminal.

[0113] After inspecting the visible parts of the generator stator winding and finding no obvious abnormalities, disconnect the generator outlet and neutral point;

[0114] Use an insulation resistance meter to locate the ground fault phase of the generator stator conductors;

[0115] Connect the current output line on the device to the faulty phase of the generator outlet;

[0116] The device uses an integrated digital programmable intelligent display terminal to control buttons to adjust and output a controllable current of 0-5A to the fault phase at the generator outlet side;

[0117] Ten wireless current clamps are used to simultaneously clamp onto the ten branches of the faulty phase, and the real-time current display values ​​of the ten channels of the integrated digital programmable intelligent display terminal are obtained. The faulty branch is determined by the magnitude of the current.

[0118] Appendix Figure 2 If all parallel branches of the faulty phase near the neutral point can be disconnected, then the current display of channels 1, 3, 4, 5, 6, 7, 8, 9, and 10 on the test instrument display screen will be 0, and the current display value of channel 2 will be the controllable current value output by the test instrument. In this case, the faulty branch is in the second branch.

[0119] Currently, most large and medium-sized generators have many branches and conductors. After the single-phase neutral point is connected in parallel with an odd number of branches and then in parallel with an even number of branches, the three phases are connected in a star configuration via flexible connections or copper busbars. In this case, if the faulty phase is closer to the neutral point, simply disconnect the flexible connection or copper busbar before the experiment and observe the changes in the current values ​​of the 10 channels on the test display screen. If the current value of the second branch is larger than the current values ​​of the other branches, then the faulty branch is on the second branch.

[0120] At the upper end of the stator winding, starting from the faulty branch near the generator outlet, clamp one wireless current clamp every six conductors according to the relevant drawings, and obtain the 10-channel real-time current display values ​​from the integrated digital programmable intelligent display terminal. The approximate location of the faulty conductor is determined by the current magnitude. (See attached diagram) Figure 2 Observation of the various current values ​​revealed that I1 > (I2 ~ I 10 If the faulty conductor is located between conductors 1 and 6, then a wireless current clamp is held at each of conductors 1 to 6 on the second branch at the upper end of the stator winding to obtain the real-time current display values ​​of 6 channels from the integrated digital programmable intelligent display terminal, as shown in the attached diagram. Figure 2 Observing the current values, we found that I1 = I2 = I3 = I4 = I5 > I6;

[0121] At the lower end of the stator winding, a wireless current clamp is held between the 5th and 6th conductors of the second branch to obtain two real-time current display values ​​from an integrated digital programmable intelligent display terminal, as shown in the attached diagram. Figure 2 Observing the current values, we found that I5 = I6, so the faulty bar is in the 6th slot.

[0122] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

[0123] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0124] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0125] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0126] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0127] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0128] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method of measuring a ground fault of a stator bar of a generator, characterized by: include, The adjustable DC voltage is obtained based on the input device voltage, and a closed loop including the frequency converter constant current source board is established based on the preset frequency and current to obtain the controllable output current. Based on the controllable output current, the stator bar grounding terminal current is obtained in conjunction with the wireless flexible current clamp. The current at the grounding end of the stator bar is transmitted to the intelligent terminal for display, and fault judgment is performed in conjunction with the fault detection logic. The fault determination process, which combines fault detection logic, includes a first logical judgment, a second logical judgment, and a third logical judgment. The first logical judgment includes the following: when all parallel branches of the generator stator bar with ground fault phase near the neutral point can be disconnected, and the current display of the 1st, 2nd, ..., ith, ... Nth channels in the display terminal is 0, and the current display value of the ith channel is the controllable current value output by the test instrument, then the fault branch is the ith branch; When the generator neutral point single phase is connected in parallel with odd-numbered branches and even-numbered branches, and the three phases are connected in a star structure through soft connections and / or copper busbars, disconnect the soft connection and / or copper busbar of the faulty phase near the neutral point and observe the change of the current value of N channels in the display terminal. If the current value of the i-th branch is larger than the current value of other branches, then the faulty branch is the i-th branch. The second logical judgment includes, At the upper end of the stator winding, starting from the fault branch near the generator outlet, a measuring unit is placed every k wires to obtain the N real-time current display values ​​of the display terminal. If I is present in the obtained current i >I 1， I i >I 2， ..., I i >I N , that is I i For I N If the maximum value is found, the faulty bar is determined to be between (i-1)*k and i*k. When the faulty bar is determined to be between (i-1)*k and i*k, a measuring unit is placed at the lower end of the stator winding on each of the (i-1)*k to i*k bars of the i-th branch. The real-time current display value of the k-channel on the display terminal is obtained again. At this time, the k-channel current display is within the mapping range of the i-th branch. The magnitude of the real-time current of the k-channel is determined. If the current of all k-1 bars except the m-th bar is equal in the real-time current of the k-path, and the real-time current value of the m-th bar is less than the current of the other k-1 bars, then the faulty bar is determined to be between the m-1 bar and the m+1 bar. The third logical judgment includes, When m is an odd number, a measuring unit is placed on the i-th branch, the m-th bar, and the (m+1)-th bar to obtain the real-time current display values ​​of the two bars on the display terminal. If I m The root line bar current is equal to I m+1根线棒电流 The fault line bar is located in the m+1 slot. When m is even, a measuring unit is placed on the i-th branch, the (m-1)-th bar, and the m-th bar to obtain the real-time current display values ​​of the two bars on the display terminal. If I m-1根线棒电流 With I m If the root line rod current is equal, the fault line rod is located in the m slot.

2. The method of claim 1, wherein: It also includes, Check the visible parts of the generator stator winding for any abnormalities. If any abnormalities are found, address the abnormal parts. If no abnormality is found, disconnect the generator outlet and neutral point, and use an insulation resistance meter to find the ground fault phase of the generator stator bar; Connect the current output line to the faulty phase of the generator output; The controllable current is adjusted and output to the fault phase at the generator outlet side via the integrated digital programmable intelligent display terminal control buttons; Using wireless current clamps to simultaneously clamp onto the branch of the faulty phase, the real-time current display values ​​of different branches of the integrated digital programmable intelligent display terminal are obtained, and the faulty branch is determined by the current magnitude. At the upper end of the stator winding, starting from the faulty branch near the generator outlet, clamp at least one wireless current clamp every fixed number of stator bars according to the stator bar structure, obtain the real-time current display value of the branch of the integrated digital programmable intelligent display terminal, and determine the location of the faulty bar by the current magnitude.

3. A system for measuring a ground fault of a generator stator bar, the system comprising: It includes a display terminal unit (100), a digital control unit (200), a frequency conversion unit (300), a power supply unit (400), a voltage and current sampling unit (500), and a measurement unit (600). The display terminal unit (100) is used to provide an intuitive human-machine interface, obtain the calculation results of the digital control unit (200), centrally display the measured current of different branches, and control the lower computer to control, measure, protect and exchange data for the whole machine. The digital control unit (200) is used to generate and output a variable frequency and amplitude sinusoidal AC waveform signal through a microcontroller program to the variable frequency constant current source board for amplification and output, exchange data with the host computer, perform calculations based on the data obtained by the measurement unit (600), and display the calculation results on the display terminal unit (100). The control unit (200) includes a data processing module (303), which includes a first logical judgment, a second logical judgment, and a third logical judgment. The first logical judgment includes the following: when all parallel branches of the generator stator bar ground fault phase near the neutral point can be disconnected, and the current display of the 1st, 2nd, ..., ith, ... Nth channels in the display terminal unit (100) is 0, and the current display value of the ith channel is the controllable current value output by the test instrument, then the fault branch is in the ith branch; When the generator neutral point single phase is connected in parallel with odd number of branches and even number of branches, and the three phases are connected in a star structure through soft connection and / or copper busbar, disconnect the soft connection and / or copper busbar of the fault phase close to the neutral point and observe the change of the current value of N channels in the display terminal unit (100). If the current value of the i-th branch is larger than the current value of other branches, then the fault branch is on the i-th branch. The second logical judgment includes, At the upper end of the stator winding, starting from the fault branch near the generator outlet side, a measuring unit (600) is placed every k wires to obtain the N-channel real-time current display values ​​of the display terminal unit (100). If I is present in the obtained current i >I 1， I i >I 2， ..., I i >I N , that is I i For I N If the maximum value is found, the faulty bar is determined to be between (i-1)*k and i*k. When the faulty bar is determined to be between (i-1)*k and i*k, a measuring unit (600) is placed at the lower end of the stator winding on each of the (i-1)*k to i*k bars of the i-th branch. The real-time current display value of the k-channel of the display terminal unit (100) is obtained again. At this time, the k-channel current display is within the mapping range of the i-th branch. The magnitude of the real-time current of the k-channel is determined. If the current of all k-1 bars except the m-th bar is equal in the real-time current of the k-path, and the real-time current value of the m-th bar is less than the current of the other k-1 bars, then the faulty bar is determined to be between the m-1 bar and the m+1 bar. The third logical judgment includes, When m is odd, a measuring unit (600) is placed on the i-th branch, the m-th bar, and the (m+1)-th bar to obtain the real-time current display value of the two bars of the display terminal unit (100). If I m The root line bar current is equal to I m+1根线棒电流 The fault line bar is located in the m+1 slot. When m is even, a measuring unit (600) is placed on the i-th branch, the (m-1)-th bar, and the m-th bar to obtain the real-time current display value of the two bars of the display terminal unit (100). If I m-1根线棒电流 With I m If the root line rod current is equal, the fault line rod is located in the m slot The frequency converter (300) is used to receive the sinusoidal signal sent by the digital control unit (200), amplify it in a controllable manner, and output the target controllable current; The power supply unit (400) is used to provide power to the whole machine, provide DC working power to the frequency converter unit (300), and provide working power to the display terminal unit (100) and the digital control unit (200); The voltage and current sampling unit (500) is used to measure the output current and feedback voltage and convert them into digital signals to provide to the digital control unit (200) for calculation; The measurement unit (600) is used to measure the stator bar grounding current and transmit the test results wirelessly to the digital control unit (200).

4. The system for measuring a ground fault of a generator stator bar of claim 3, wherein: The power supply unit (400) includes a rectifier and filter module (401), a voltage regulator module (402), and an auxiliary power supply module (403). When the system is working, the voltage regulator module (402) provides DC power to the frequency converter unit (300), the auxiliary power module (403) provides a fixed DC voltage to the display terminal unit (100) and the digital control unit (200), and the rectifier and filter module (401) provides a low-interference, low-ripple power supply to the voltage regulator module (402) and the auxiliary power module (403). When the frequency converter (300) receives the sinusoidal signal from the digital control unit (200), the frequency converter (300) provides an AC current signal with a preset frequency and current to the generator stator bars; When a ground current is generated at the grounding end of the stator bar, the ground current is measured by the multi-channel wireless flexible current clamp held on the stator bar at different positions and transmitted wirelessly to the display terminal unit (100) for display. The ground current data is also transmitted to the control unit (200) for logical judgment and calculation. When the grounding current data result is determined, the determination result is mapped and displayed with the input grounding current data, and the mapping result is transmitted to the display terminal unit (100) to refresh the display content.

5. The system for measuring a ground fault of a generator stator bar of claim 4, wherein: The control unit (200) also includes a start-stop control module (201) and a data receiving and sending module (202). The start-stop control module (201) receives start-stop control commands sent by the display terminal unit (100). When the system is working, the user sends a start command through the display terminal unit (100). After the start-stop control module (201) receives the start command, the control unit (200) performs the operation. The user obtains the grounding current through the measurement unit (600). Before the user obtains the grounding current through the measuring unit (600) for measurement, check whether there is any abnormality in the visible part of the generator stator winding. If there is any abnormality, deal with the abnormal part. If no abnormality is found, disconnect the generator outlet and neutral point, and use an insulation resistance meter to find the ground fault phase of the generator stator bar; Connect the current output line on the system to the faulty phase at the generator outlet, and adjust and output a controllable current to the faulty phase at the generator outlet side through the control buttons of the system's display terminal unit (100); Using N wireless current clamps to simultaneously clamp onto N branches of the faulty phase, observe the N real-time current display values ​​of the display terminal unit (100), and determine the faulty branch by inputting the current into the data processing module (303), where N is the number of branches of the faulty phase. 6.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-5 when the computer program is executed by the processor. When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 2.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 2.

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