Frequency Response-Based Distribution Transformer Winding Fault Location Method and System
By establishing symmetrical current distribution in transformer windings through triangular connection and signal comparison, the method addresses the inaccuracy of existing frequency response analysis, enabling efficient fault diagnosis and location in transformer windings.
Patent Information
- Application Number
- CN202210664209.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-14
- Publication Date
- 2025-07-15
- Estimated Expiration
- 2042-06-14
AI Technical Summary
In the prior art, the frequency response analysis method cannot accurately determine the fault location in the transformer winding fault diagnosis, especially for triangular three-phase transformers, there is a problem of asymmetry leading to inaccurate diagnosis.
By changing the wiring method, the phase current distribution symmetry of the three-phase windings to be tested is established, and the fault position is judged using the frequency response signal, including short-circuiting the low-voltage three-phase winding and the high-voltage three-phase winding to form a symmetrical wiring structure, and the fault phase is judged by the comparison of the frequency response signal of the mesospheric phase and the outer phase.
It realizes accurate positioning of transformer winding faults, simplifies the judgment process, improves diagnostic efficiency, and supports automated detection and modular integration, suitable for mass production and industrialization.
Smart Images
Figure CN115166594B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of operation and maintenance of power distribution equipment, and particularly to a method and system for fault location of a power distribution transformer winding. Background Art
[0002] During the operation of a power distribution transformer, surges or short - circuit phenomena in its windings usually generate electrical and mechanical stresses, which are likely to cause transformer winding faults, including winding damage or deformation, etc. If transformer winding faults are not detected in the early stage, it may lead to serious problems, including the failure shutdown of the transformer, which in turn affects the safe operation of the power grid and may cause huge economic losses. Therefore, the detection and identification of early transformer faults have always been one of the research focuses of transformer condition monitoring.
[0003] The frequency response analysis method is a relatively commonly used means for detecting transformer winding faults. Its principle is simple. With the development of condition monitoring technology, the frequency response analysis method has also been greatly improved. For transformer fault detection, the frequency response analysis method has sufficient sensitivity. However, in traditional applications, the frequency response analysis method only simply measures the comparison between the obtained frequency response and the standard reference quantity, and never determines whether the transformer is faulty, and fails to provide data for fault location, fault degree, and fault type judgment.
[0004] Therefore, on this basis, many research works have proposed transformer winding fault assessment technologies based on intelligent algorithms. In contrast, there is less research on fault location. Especially for three - phase transformers with "delta connection", their wiring method has asymmetry, that is, the current distribution in each phase itself is uneven. This uneven distribution of current will lead to inaccuracies in fault diagnosis using frequency response analysis, which is very complex and challenging for "delta - connected" windings. Currently, there is still a lack of simple and widely applicable winding fault location technologies. Summary of the Invention
[0005] The purpose of the present invention is to solve the problems existing in the above - mentioned prior art, and provide a method for fault location of a power distribution transformer winding based on frequency response, so as to solve the technical problem of how to improve the accuracy of fault diagnosis using frequency response analysis.
[0006] The present invention is achieved through the following technical solutions: A method for fault location of a distribution transformer winding based on frequency response, comprising the following steps: By short-circuiting the lead-out ends of the three-phase windings to be measured that form a delta connection, the symmetry of the phase current distribution of the three-phase windings to be measured is established; Any one of the three-phase windings to be measured is used as the middle phase, and the other two-phase windings are used as the outer phases; An excitation signal is input through the lead-out end of the winding corresponding to the middle phase, and the frequency response signals are measured respectively through the lead-out ends of the windings corresponding to the two outer phases; According to whether the frequency response signals of the two outer-phase windings are the same, it is judged whether a fault occurs in the middle phase.
[0007] Further, it includes the following steps:
[0008] Short-circuit the low-voltage three-phase winding of the distribution transformer:
[0009] The low-voltage three-phase winding is in a star connection. The lead-out ends of the low-voltage three-phase winding are short-circuited and grounded;
[0010] Short-circuit the high-voltage three-phase winding of the distribution transformer:
[0011] The high-voltage three-phase winding is in a delta connection and serves as an inner delta connection structure. The lead-out ends of the high-voltage three-phase winding are short-circuited to form an outer delta connection structure. Through the cancellation effect of the outer delta connection structure on the asymmetry generated by the inner delta connection structure, the symmetry of the phase current distribution is established in the inner delta connection structure;
[0012] Measure the frequency response signal:
[0013] Any one of the high-voltage three-phase windings is used as the initial middle phase, and the other two-phase windings are used as the initial outer phases; An excitation signal is input through the lead-out end of the winding corresponding to the initial middle phase, and the frequency response signals are measured respectively through the lead-out ends of the windings corresponding to the two initial outer phases;
[0014] Judge the fault occurrence location according to the frequency response signal:
[0015] If the frequency response signals of the two outer phases are the same, it is judged that the winding corresponding to the initial middle phase has a fault; If the frequency response signals of the two outer phases are different, it is judged that the winding corresponding to one of the two initial outer phases has a fault.
[0016] Further, when it is judged that the winding corresponding to one of the two initial outer phases has a fault, any one of the windings corresponding to the two initial outer phases is used as the new middle phase, and the other two-phase windings are used as the new outer phases;
[0017] An excitation signal is input through the lead-out end of the winding corresponding to the new middle phase, and the frequency response signals of the windings corresponding to the two new outer phases are measured again;
[0018] Determine whether the fault occurs in the new middle phase according to whether the frequency response signals are the same. If so, determine that the winding corresponding to the new middle phase is the faulty phase. If not, determine that the winding corresponding to the original outer phase among the two new outer phases is the faulty phase.
[0019] The present invention also provides a distribution transformer winding fault location system based on frequency response for implementing the distribution transformer winding fault location method based on frequency response of the present invention, and includes:
[0020] A detection device and a host computer, the detection device includes a power supply module, a collection module, a communication module, and a signal processing module;
[0021] The power supply module is used to provide power for the collection module, the communication module, and the signal processing module, and is used to output an excitation signal to the middle phase;
[0022] The collection module is used to collect the frequency response signals of the outer phases;
[0023] The signal processing module is used to preprocess the frequency response signals;
[0024] The communication module is used to send the preprocessed frequency response signals to the host computer;
[0025] The host computer is used to determine the fault occurrence location according to the frequency response signals.
[0026] Furthermore, the detection device further includes an expansion module, and the expansion module is used to provide a modular integration interface.
[0027] Furthermore, the preprocessing operation of the signal processing module on the frequency response includes adding the phase sequence number corresponding to the corresponding winding to the frequency response signals of the outer phase windings
[0028] Furthermore, the host computer determines the fault occurrence location through a fault location program configured internally, and includes the following steps:
[0029] Step1: Set the initial value of the loop variable to T0;
[0030] Step2: Obtain the frequency response signals of the two outer phases in real time, and identify the phase sequence number of the winding corresponding to the middle phase according to the phase sequence numbers in the frequency response signals of the two outer phases;
[0031] Step3: Determine whether the frequency response signals of the two outer phases are the same; if the same, determine that the winding corresponding to the middle phase has a fault, take the phase sequence number of the winding corresponding to the middle phase as the phase sequence number of the faulty winding and forward it, and the program ends; if not the same, enter Step4;
[0032] Step 4: Determine whether the loop variable is greater than T0; if not, return to Step 2 and increment the loop variable by 1; if so, determine whether the winding that has not served as an intermediate phase has a fault, and forward the phase sequence number of the corresponding winding as the phase sequence number of the faulty winding, and the program ends.
[0033] Compared with the prior art, the beneficial effects of the present invention include:
[0034] 1. The present invention establishes the symmetry of the phase current distribution of the three-phase windings to be measured by changing the wiring method. Therefore, based on the wiring method of the present invention, the faulty phase can be accurately determined by the frequency response analysis method.
[0035] 2. The present invention determines whether the faulty phase is an intermediate phase by judging whether the frequency response signals of the two outer-phase windings are the same. It requires fewer parameters and does not require complex calculations and calibration of standard reference quantities, making the frequency response analysis simpler and more efficient, and having the potential for practical promotion in the discrimination of faulty phases of transformers.
[0036] 3. When the present invention determines that the fault does not occur in the intermediate phase, the intermediate phase can be reselected to continue to judge whether the new intermediate phase is the faulty phase, and finally the faulty phase can be accurately located.
[0037] 4. Since it can be determined whether the intermediate phase has a fault with one judgment, when the intermediate phase is not faulty, only the intermediate phase needs to be reselected and a second judgment can be made to perform fault location, greatly improving the fault location efficiency.
[0038] 5. The device wiring and structural modules of the present invention are relatively simple. It can not only achieve independent automatic detection and automatic detection based on host computer instructions, but also reserve expansion modules, provide modular integration interfaces, and can output multiple excitation signals through the modular interfaces to detect multiple transformers. It can be modularly integrated according to the requirements of different automatic detection devices, which is conducive to the further promotion of automation and is conducive to mass production and industrialization. Description of the Drawings
[0039] Figure 1 is a flowchart of a method for locating faults in the windings of a distribution transformer;
[0040] Figure 2 is a wiring schematic diagram of a distribution transformer;
[0041] Figure 3 is a structural schematic diagram of a detection device. Detailed Embodiment
[0042] The present invention will be further described in detail below with reference to the drawings:
[0043] Reference Figure 1As shown, a method for fault location of a distribution transformer winding based on frequency response includes the following steps: short-circuiting the leads of the three-phase windings to be measured that form a delta connection to establish the symmetry of the phase current distribution of the three-phase windings to be measured; taking any one of the three-phase windings to be measured as the middle phase, and the other two-phase windings as the outer phases; inputting an excitation signal through the lead of the winding corresponding to the middle phase, and measuring the frequency response signals respectively through the leads of the windings corresponding to the two outer phases; and judging whether a fault occurs in the middle phase according to whether the frequency response signals of the two outer-phase windings are the same.
[0044] Since symmetry is established, if no fault occurs in the two outer phases, the frequency response signals should be the same, and only the middle phase can have a fault. If the frequency response signals are different, then a fault occurs in one of the two outer phases. For the case of faults in three phases or two phases simultaneously, it can be very clearly identified only by the operating state of the equipment. In addition, the fault in the present invention refers to damage or deformation of the winding.
[0045] Reference Figure 2 As shown, this specific embodiment is described by taking the high-voltage three-phase winding as the three-phase winding to be measured as an example.
[0046] To meet the test requirements of the frequency response method, short-circuit the low-voltage three-phase windings of the distribution transformer:
[0047] The low-voltage three-phase windings are in a star connection. Short-circuit and ground the leads of the low-voltage three-phase windings; the three phases on the low-voltage side are respectively named phase 2A, phase 2B, and phase 2C, where 2B is the middle phase and 2A and 2C are the outer phases.
[0048] Short-circuit the high-voltage three-phase windings of the distribution transformer:
[0049] The high-voltage three-phase windings are in a delta connection and serve as an inner delta connection structure. Short-circuit the leads of the high-voltage three-phase windings to form an outer delta connection structure. Through the cancellation effect of the outer delta connection structure on the asymmetry generated by the inner delta connection structure, the symmetry of the phase current distribution is established in the inner delta connection structure.
[0050] Name the three-phase windings on the high-voltage side as phase 1A, phase 1B, and phase 1C respectively. Before establishing the outer delta connection structure, the port connections are the inner delta 1A1-1C2, 1B1-1A2, 1C1-1B2; after establishing the outer delta, that is, after short-circuiting 1A1-1B1-1C1, 1A1-1B2, 1B1-1C2, and 1C1-1A2 are added, which exactly cancels out with the inner delta to form a symmetric structure. The outer delta connection structure generates an increment of the outer delta through the excitation signal, which can make the current evenly distributed in each phase.
[0051] Measure the frequency response signals:
[0052] Taking any one of the high-voltage three-phase windings 1A, 1B, and 1C as the initial intermediate phase, and the remaining two-phase windings as the initial outer phases. For example, phase 1B is the initial intermediate phase, and 1A and 1C are both initial outer phases. An excitation signal is input through the lead-out end of the winding corresponding to the initial intermediate phase, and the frequency response signals are measured respectively through the lead-out ends of the windings corresponding to the two initial outer phases.
[0053] An AC voltage signal is input as the excitation signal to the lead-out end of the initial intermediate phase 1B. This excitation signal first causes an excitation phase current in the intermediate phase 1B. When this excitation phase current flows through the outer phases 1A and 1C, it causes induced currents in the outer phases, and the frequency response signals I L (s), I R (s) are both the superposition of the excitation phase current and the induced current.
[0054] If the frequency response signals of the two outer phases are the same, it is determined that the winding corresponding to the initial intermediate phase has a fault; if the frequency response signals of the two outer phases are different, it is determined that the winding corresponding to one of the initial outer phases has a fault.
[0055] When it is determined that the winding corresponding to one of the initial outer phases has a fault, any one of the windings corresponding to the two initial outer phases is taken as the new intermediate phase, and the remaining two-phase windings are taken as the new outer phases;
[0056] An excitation signal is input through the lead-out end of the winding corresponding to the new intermediate phase, and the frequency response signals of the windings corresponding to the new two outer phases are measured again;
[0057] According to whether the frequency response signals are the same, it is determined whether the fault occurs in the new intermediate phase. If so, it is determined that the winding corresponding to the new intermediate phase is the fault phase; if not, it is determined that the winding corresponding to the original initial outer phase among the new two outer phases is the fault phase.
[0058] For the convenience of remote detection, a distribution transformer winding fault location system based on frequency response is also provided, including a detection device and a host computer.
[0059] Refer to Figure 3 As shown, the detection device includes a power supply module, a collection module, a communication module, and a signal processing module.
[0060] The power supply module is used to provide power for the collection module, the communication module, and the signal processing module, and is also used to output an excitation signal to the intermediate phase.
[0061] The collection module is used to collect the frequency response signals of the outer phases; the collection module includes current sensors respectively used to connect to the lead-out ends of the two outer-phase windings.
[0062] The signal processing module is used to preprocess the frequency response signals.
[0063] The communication module is used to send the preprocessed frequency response signal to the host computer.
[0064] The host computer is used to judge the fault occurrence position according to the frequency response signal.
[0065] In this specific embodiment, the preprocessing operation of the signal processing module on the frequency response includes adding the phase sequence number corresponding to the corresponding winding to the frequency response signal of the outer-phase winding.
[0066] In this specific embodiment, the host computer judges the fault occurrence position through the internally configured fault location program, and includes the following steps:
[0067] Step1: Set the initial value of the loop variable to T0;
[0068] Step2: Obtain the frequency response signals of the two outer phases in real time, and identify the phase sequence number of the corresponding winding of the middle phase according to the phase sequence numbers in the frequency response signals of the two outer phases;
[0069] Step3: Judge whether the frequency response signals of the two outer phases are the same; if they are the same, judge that the corresponding winding of the middle phase has a fault, take the phase sequence number of the corresponding winding of the middle phase as the phase sequence number of the faulty winding and forward it, and the program ends; if they are not the same, enter Step4;
[0070] Step4: Judge whether the loop variable is greater than T0; if not, return to Step2, and increment the loop variable by 1; if so, judge that the winding that has not been used as the middle phase has a fault, and take the phase sequence number of the corresponding winding as the phase sequence number of the faulty winding and forward it, and the program ends.
[0071] In this specific embodiment, the detection device further includes an expansion module, and the expansion module is used to provide a modular integration interface. Multiple excitation signals can be output through the modular interface to detect multiple transformers, and modular integration can be carried out according to the requirements of different automatic detection devices, which is beneficial to the further popularization of automation and is conducive to mass production and industrialization.
[0072] In this specific embodiment, the detection device further includes a controller, and the controller is used to receive the detection instruction from the host computer and automatically control the frequency response signal measurement process.
[0073] To realize the automatic switching of the middle phase, the excitation signal output terminals of the power supply module are respectively connected to the lead-out terminals of the three-phase windings through three channels, and relays are arranged on each channel. Thus, the controller can control whether to output the excitation signal with a certain phase winding as the middle phase by controlling the on-off of the relay. As for the probe of the current sensor, it needs to be manually switched to the outer winding on site.
[0074] The above technical solution is only one implementation manner of the present invention. For those skilled in the art, based on the disclosed principle of the present invention, it is very easy to make various types of improvements or deformations, not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the foregoing description is only preferred and does not have a restrictive meaning.
Claims
1. A method for fault location of distribution transformer windings based on frequency response, characterized in that, Including the following steps: By short - circuiting the leads of the three - phase windings under test that form a triangular connection, the symmetry of the phase - current distribution of the three - phase windings under test is established, including: Short - circuiting the low - voltage three - phase windings of the distribution transformer: The low - voltage three - phase windings are star - connected. Short - circuit and ground the leads of the low - voltage three - phase windings. Short - circuiting the high - voltage three - phase windings of the distribution transformer: The high - voltage three - phase windings are delta - connected and used as an inner - delta connection structure. Short - circuit the leads of the high - voltage three - phase windings to form an outer - delta connection structure. Through the cancellation effect of the outer - delta connection structure on the asymmetry generated by the inner - delta connection structure, the symmetry of the phase - current distribution is established in the inner - delta connection structure. Taking any one of the three - phase windings under test as the intermediate phase, and the other two - phase windings as the outer - side phases. Input an excitation signal through the lead of the winding corresponding to the intermediate phase, and measure the frequency - response signals respectively through the leads of the windings corresponding to the two outer - side phases. According to whether the frequency - response signals of the two outer - side windings are the same, determine whether a fault occurs in the intermediate phase.
2. The method for fault location of a distribution transformer winding based on frequency response according to claim 1, wherein Including the following steps: Measuring the frequency - response signal: Taking any one of the high - voltage three - phase windings as the initial intermediate phase, and the other two - phase windings as the initial outer - side phases. Input an excitation signal through the lead of the winding corresponding to the initial intermediate phase, and measure the frequency - response signals respectively through the leads of the windings corresponding to the two initial outer - side phases. Judging the fault location according to the frequency - response signal: If the frequency - response signals of the two outer - side phases are the same, it is judged that the winding corresponding to the initial intermediate phase has a fault; if the frequency - response signals of the two outer - side phases are different, it is judged that one of the windings corresponding to the two initial outer - side phases has a fault.
3. The method for fault location of a distribution transformer winding based on frequency response according to claim 2, characterized in that, When it is judged that one of the windings corresponding to the two initial outer - side phases has a fault, take any one of the windings corresponding to the two initial outer - side phases as the new intermediate phase, and the other two - phase windings as the new outer - side phases. Input an excitation signal through the lead of the winding corresponding to the new intermediate phase, and re - measure the frequency - response signals of the windings corresponding to the two new outer - side phases. Judge whether a fault occurs in the new intermediate phase according to whether the frequency - response signals are the same. If so, judge that the winding corresponding to the new intermediate phase is the fault phase; if not, judge that the winding corresponding to the initial outer - side phase among the two new outer - side phases is the fault phase.
4. The method for fault location of a distribution transformer winding based on frequency response according to any one of claims 1 to 3, characterized in that, The excitation signal is an AC voltage signal, and the frequency - response signal is a current signal.
5. A distribution transformer winding fault location system based on frequency response, characterized in that, For implementing the method for fault location of distribution - transformer windings based on frequency response as described in claim 1, and including: A detection device and a host computer. The detection device includes a power - supply module, a collection module, a communication module, and a signal - processing module. The power - supply module is used to provide power for the collection module, the communication module, and the signal - processing module, and is used to output an excitation signal to the intermediate phase. The collection module is used to collect the frequency - response signals of the outer - side phases. The signal - processing module is used to pre - process the frequency - response signals. The communication module is used to send the pre - processed frequency - response signals to the host computer. The host computer is used to judge the fault location according to the frequency - response signals.
6. The frequency response-based distribution transformer winding fault location system according to claim 5, wherein The collection module includes current sensors respectively used to connect the leads of the two outer - side windings.
7. The frequency response-based distribution transformer winding fault location system according to claim 5, characterized in that The detection device further includes an expansion module, and the expansion module is used to provide a modular integration interface.
8. The frequency response-based distribution transformer winding fault location system according to claim 5, characterized in that The preprocessing operation of the signal processing module on the frequency response includes adding the phase sequence number corresponding to the respective winding to the frequency response signal of the outer-phase winding 9. The frequency response-based distribution transformer winding fault location system according to claim 8, characterized in that The host computer judges the fault occurrence location through a fault location program configured internally, and includes the following steps: Step1: Set the initial value of the loop variable to T0; Step2: Obtain the outer two-phase frequency response signals in real time, and identify the phase sequence number of the corresponding winding of the middle phase according to the phase sequence numbers in the outer two-phase frequency response signals; Step3: Judge whether the outer two-phase frequency response signals are the same; if they are the same, judge that the corresponding winding of the middle phase has a fault, take the phase sequence number of the corresponding winding of the middle phase as the phase sequence number of the faulty winding and forward it, and the program ends; If they are not the same, go to Step4; Step4: Judge whether the loop variable is greater than T0; if not, return to Step2, and increment the loop variable by 1; If it is, judge that the winding that has not served as the middle phase has a fault, and take the phase sequence number of the corresponding winding as the phase sequence number of the faulty winding and forward it, and the program ends.
10. The frequency response-based distribution transformer winding fault location system according to claim 5, characterized in that, The detection device further includes a controller, and the controller is used to receive the detection instruction from the host computer and automatically control the measurement process of the frequency response signal.
Citation Information
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