Integrated sensor for dry-type transformer and electromechanical state detection method
By embedding piezoelectric sensitive elements and signal conditioning circuits within the fastening bolts of dry-type transformers, the problems of signal drift and system redundancy caused by the separation of sensors from transformers are solved, realizing the self-sensing intelligence of dry-type transformers and improving power grid security and monitoring accuracy.
Patent Information
- Application Number
- CN202511206545.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-27
- Publication Date
- 2025-11-14
AI Technical Summary
Existing dry-type transformers lack real-time monitoring capabilities. The physical separation of sensors from the transformer body leads to measurement signal drift and system redundancy, and insufficient anti-interference capabilities, affecting power grid security.
An embedded integrated sensor is designed to simultaneously measure and process wideband vibration signals by integrating a piezoelectric sensitive element and a signal conditioning circuit inside the fastening bolt of a dry transformer, and to integrate the data with a wireless transmission module.
It enables wideband vibration signal measurement at the same location and time, reduces signal drift and system redundancy, improves anti-interference capability, transforms dry-type transformers into self-sensing intelligent nodes, and supports the digitalization of distribution networks.
Smart Images
Figure CN120947739A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power system automation technology, and in particular to an integrated sensor and electromechanical condition detection method for dry-type transformers. Background Technology
[0002] As a core component of the power distribution system, the reliability of dry-type transformers directly impacts power grid security. However, traditional dry-type transformers generally suffer from "sensing blind spots," relying primarily on periodic manual inspections and passive maintenance, lacking real-time monitoring capabilities for their operating status. With the development of the energy internet, power distribution systems require interconnected equipment and comprehensive data sensing, making the intelligent upgrading of dry-type transformers an inevitable trend.
[0003] Currently, the existing implementations most similar to this invention mainly fall into two categories. First, monitoring the condition by installing independent sensors on the transformer body or casing is a typical "retrofit" approach. Second, fixing vibration and partial discharge sensors by drilling holes in the transformer casing requires a power outage, involves complex wiring, and is prone to loosening over long-term operation, leading to signal drift. While this achieves multi-parameter acquisition, the sensors and transformer body remain physically separate. Third, although fiber optic temperature measurement is integrated with the coil, vibration and partial discharge sensors need to be fixed separately, requiring a power outage for installation, and the wiring is complex and prone to loosening and shifting over long-term operation, resulting in decreased measurement stability.
[0004] While air-coupled non-contact UHF-ultrasonic sensors (such as composite partial discharge detectors) support live installation, their anti-interference capabilities are weak. Although this solution achieves "live installation" and solves the problem of convenient operation and maintenance, its reliance on air-borne signal propagation results in significantly insufficient anti-interference capabilities. Field tests show that in complex electromagnetic environments, UHF signals are easily affected by spatial clutter, while ultrasonic signals are easily submerged by environmental noise, leading to an increased false alarm rate in partial discharge detection, especially with insufficient sensitivity to early, weak discharges.
[0005] In the collaborative detection of mechanical and insulation faults in power equipment, two heterogeneous sensing devices—vibration sensors and ultrasonic sensors—need to be deployed. Traditional sensor monitoring schemes suffer from problems such as lack of spatiotemporal synchronization and excessive system redundancy. First, because vibration sensors need to be rigidly fixed to the equipment housing (such as transformer clamps), while ultrasonic sensors need to be close to the sound source (such as a discharge point), their physical installation positions cannot coincide. This results in spatial differences and time delays between the collected mechanical vibration signals and ultrasonic signals, disrupting the spatiotemporal correlation of fault characteristics and increasing the error in diagnosing composite faults. Second, to achieve simultaneous detection of electromechanical conditions, two types of sensors are required, each with its own independently configured signal conditioning circuit, power supply module, and communication interface. This increases the equipment installation space required, and the parallel processing of vibration-ultrasonic dual-channel data leads to increased system power consumption, resulting in both structural and functional redundancy. Summary of the Invention
[0006] The purpose of this invention is to propose an integrated sensor and electromechanical condition detection method for dry-type transformers, which solves the technical problems of signal drift and equipment redundancy in existing multi-source asynchronous data acquisition and external sensors.
[0007] On the one hand, an integrated sensor for dry-type transformers is provided, comprising:
[0008] A bolt, which can be installed on the dry-type transformer, has an internal cavity. The bolt serves as the housing of the integrated sensor and is grounded by connecting to a clamp installed on the dry-type transformer.
[0009] A matching layer is disposed within the cavity, and a piezoelectric sensitive element is disposed on the matching layer; an electrode layer is disposed on the upper and lower surfaces of the piezoelectric sensitive element, and a steering support is disposed on the piezoelectric sensitive element; the bottom end of the steering support is perpendicularly disposed to the piezoelectric sensitive element, and the top end of the steering support is connected to the upper surface of the bolt and is provided with an output port;
[0010] The matching layer is used as a base for a low-frequency vibration sensor or a high-frequency ultrasonic sensor.
[0011] The electrode layer includes a piezoelectric material and metal electrodes laid on its upper and lower surfaces, used to extract the charge signal induced by the piezoelectric material under the influence of the electromechanical state of the equipment;
[0012] The steering strut is used to extract the collected broadband vibration signal;
[0013] The output port is used to connect to subsequent signal conditioning circuits to achieve wideband vibration signal processing and analysis.
[0014] Preferably, a backing is also provided on the inner wall of the cavity, and the backing is disposed adjacent to the matching layer, the piezoelectric sensitive element and the steering pillar respectively.
[0015] Preferably, a mass block is further provided inside the cavity, the mass block being used to fill the space inside the cavity.
[0016] Preferably, the clamp includes at least an upper clamp and a lower clamp, which are respectively disposed on the upper and lower sides of the bolt for fixing the bolt; the upper clamp on the same side or the lower clamp on the same side share a signal conditioning circuit, and a wireless transmission module is provided inside the clamp for signal transmission.
[0017] Preferably, the signal conditioning circuit is located on the upper clamp or the lower clamp closest to the bolt.
[0018] Preferably, the bolt includes at least a winding fastening bolt, wherein the upper end or lower end of the winding of the winding fastening bolt shares a signal conditioning circuit.
[0019] On the other hand, a method for detecting the electromechanical condition of a dry-type transformer is also provided, which is implemented using the integrated sensor, including:
[0020] The vibration signal of the dry-type transformer is detected by the piezoelectric sensitive element, wherein the vibration signal includes at least the low-frequency vibration signal change of the overall system caused by mechanical loosening and the high-frequency signal of partial discharge caused by insulation defects;
[0021] The vibration signal is converted into a charge signal and transmitted to an external signal conditioning circuit; the difference between the vibration signals before and after the mechanical fault is judged based on the change of the vibration signal, and the mechanical fault detection of dry-type transformer is realized.
[0022] In summary, implementing the embodiments of the present invention has the following beneficial effects:
[0023] The integrated sensor and electromechanical condition detection method for dry-type transformers provided by this invention can simultaneously measure broadband vibration signals at the same location and time, achieving mechanical integration (embedded inside the fastening bolts), electrical integration (pre-cast sensing modules), and data integration (unified time scale). This enables dry-type transformers to evolve from "passive power supply equipment" to "self-sensing intelligent nodes," providing key technical support for the digitalization of distribution networks. Attached Figure Description
[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.
[0025] Figure 1 This is a schematic diagram of an integrated sensor for a dry-type transformer according to an embodiment of the present invention.
[0026] Figure 2 This is a schematic diagram of an integrated sensor for a dry-type transformer according to an embodiment of the present invention.
[0027] Figure 3 This is a schematic diagram of a signal conditioning method according to an embodiment of the present invention.
[0028] Figure 4 This is a schematic diagram of a broadband vibration signal of a dry-type transformer with only insulation defects in an embodiment of the present invention.
[0029] Figure 5 This is a schematic diagram of broadband vibration signal of a dry-type transformer under a composite insulation and mechanical defect in an embodiment of the present invention. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.
[0031] like Figure 1 and Figure 2 The diagram shown is a schematic representation of an embodiment of an integrated sensor for dry-type transformers provided by the present invention. This embodiment includes:
[0032] A bolt, which can be installed on the dry-type transformer, has an internal cavity. The bolt serves as the housing of the integrated sensor and is grounded by connecting to a clamp on the dry-type transformer. A matching layer 1 is installed inside the cavity, and a piezoelectric sensitive element 2 is installed on the matching layer 1. An electrode layer 4 is installed on the upper and lower surfaces of the piezoelectric sensitive element 2, and a steering column 5 is installed on the piezoelectric sensitive element 2. The bottom end of the steering column 5 is perpendicular to the piezoelectric sensitive element 2, and the top end of the steering column 5 is connected to the upper surface of the bolt and has an output port. The matching layer 1 is used as a base for a low-frequency vibration sensor or a high-frequency ultrasonic sensor. The electrode layer 4 includes piezoelectric material and metal electrodes laid on its upper and lower surfaces, used to extract the charge signal induced by the piezoelectric material under the influence of the electromechanical state of the equipment. The steering column 5 is used to extract the collected broadband vibration signal. The output port is used to connect to a subsequent signal conditioning circuit to realize the processing and analysis of the broadband vibration signal.
[0033] Specifically, a backing is provided on the inner wall of the cavity, and the backing is respectively arranged adjacent to the matching layer 1, the piezoelectric sensitive element 2 and the steering support 5. A mass block 3 is also provided in the cavity, and the mass block 3 is used to fill the space in the cavity.
[0034] The clamping component includes at least an upper clamping component and a lower clamping component, which are respectively disposed on the upper and lower sides of the bolt for fixing the bolt. The upper clamping component or the lower clamping component on the same side shares a signal conditioning circuit, and a wireless transmission module is disposed within the clamping component for signal transmission. The signal conditioning circuit is disposed on the upper clamping component or the lower clamping component closest to the bolt.
[0035] In one specific embodiment of the present invention, the original bolt metal material is used as the outer shell of the integrated sensor. The sensor structure is embedded inside the bolt head, comprising a matching layer 1, a piezoelectric sensitive element 2, a mass block 3, upper and lower surface electrode layers 4, an axial support, an output port, and a shell. Matching layer 1: An alumina material with an acoustic impedance of 36MRal and high hardness is selected, which can simultaneously function as a low-frequency vibration sensor base and a high-frequency ultrasonic sensor matching layer 1. Piezoelectric sensitive element 2: A piezoelectric material with a high piezoelectric coefficient, such as the PZT-5 series, is selected. If green environmental protection requirements are required, a high-performance lead-free piezoelectric material can be selected. Mass block 3: Epoxy resin and tungsten powder are cast into the remaining sensor cavity to absorb excess reflected ultrasonic signals and increase the mass of the cast portion, allowing it to simultaneously function as mass block 3 and a backing. Upper and lower surface electrodes: Metal electrodes are laid on the upper and lower surfaces of the piezoelectric material to extract the charge signals induced by the electromechanical state of the equipment. Axial support: The acquired broadband vibration signal is led out using a metal support instead of metal wires, enhancing the connection stability of the embedded integrated sensor. Output port: Connects to subsequent signal conditioning circuitry to achieve broadband vibration signal processing and analysis. Housing: The bolts are originally made of metal and are grounded along with the clamps and other components. Using them as the housing for the embedded integrated sensor enables functions such as interference shielding and housing grounding.
[0036] The bolts include at least winding fastening bolts, with each winding's upper or lower end sharing a signal conditioning circuit. For core clamping bolts, the upper and lower clamps on the same side each share a signal conditioning circuit, including a wireless transmission module. For winding fastening bolts, the upper and lower ends of the winding each share a signal conditioning circuit, including a wireless transmission module. The signal conditioning circuits are fixed near the corresponding clamp positions. The main functions of the signal conditioning circuits are charge conversion, amplification, filtering and separation, and wireless transmission. To achieve electromechanical condition monitoring and fault location of dry-type transformers, sensors can be optionally placed inside the three-phase winding bolts / core clamping bolts. Replacing each bolt with an integrated sensor can achieve accurate electromechanical fault location in dry-type transformers, but this results in sensor redundancy and high application costs. The upper AC phase core and winding clamping bolts of the transformer, and the lower B phase core and winding clamping bolts of the transformer are replaced with the embedded integrated sensors described in this invention.
[0037] In this embodiment, the integrated sensor structure design incorporates a broadband vibration sensor within the fastening bolts of the dry-type transformer, achieving an integrated design of the dry-type transformer and sensor. Separate signal conditioning modules are matched to the integrated sensors at different locations. For example, the core clamping bolts, upper and lower clamps on the same side share a single signal conditioning circuit, enabling functions such as charge conversion amplification, filtering separation, and wireless transmission. To achieve fault detection and location in the dry-type transformer, a differentiated sensor arrangement scheme is designed, replacing only the AC phase core and winding clamping bolts in the upper half of the transformer and the B phase core and winding clamping bolts in the lower half with the embedded integrated sensor of this invention. Finally, defects in the dry-type transformer are detected. For different faults, the broadband signal detected by the integrated sensor is as follows: Figure 4-5 As shown, when insulation defects exist within a dry-type transformer, the integrated broadband vibration sensor acquires a low-frequency periodic signal, superimposed with intermittent high-frequency partial discharge signals. Spectral analysis of the low-frequency vibration component reveals its dominant frequency to be 100Hz. When both insulation defects and mechanical faults coexist within the dry-type transformer, the integrated broadband vibration sensor detects high-frequency partial discharge signals. Simultaneously, the dominant frequency of the low-frequency mechanical wave is 200Hz, which differs from the dominant frequency of the dry-type transformer under normal conditions. Therefore, frequency domain analysis of the acquired broadband vibration signals can provide a preliminary assessment of whether electromechanical defects exist within the dry-type transformer.
[0038] An embodiment of the present invention also provides a method for detecting the electromechanical condition of a dry-type transformer, implemented using the aforementioned integrated sensor, comprising:
[0039] The vibration signal of the dry-type transformer is detected by the piezoelectric sensitive element 2, wherein the vibration signal includes at least the low-frequency vibration signal change of the overall system caused by mechanical loosening and the high-frequency signal of partial discharge caused by insulation defects;
[0040] The vibration signal is converted into a charge signal and transmitted to an external signal conditioning circuit; the difference between the vibration signals before and after the mechanical fault is judged based on the change of the vibration signal, and the mechanical fault detection of dry-type transformer is realized.
[0041] By using a piezoelectric sensing element 2 embedded inside the fastening bolts of a dry-type transformer, changes in low-frequency vibration signals of the overall system caused by mechanical loosening and high-frequency signals of partial discharge caused by insulation defects can be detected. For example... Figure 3 As shown, its specific principle is as follows:
[0042] a. Mechanical Fault Detection Based on Low-Frequency Vibration Signals. Vibration signals from the power equipment are transmitted through various connectors to integrated sensors inside the corresponding fastening bolts. These sensors are then transmitted via a matching layer 1 / base to the piezoelectric sensing element 2. A mass block 3, composed of a mixture of epoxy resin and tungsten powder, is used to increase the transmission efficiency of low-frequency vibrations. The piezoelectric sensing element 2 converts the vibration signal into an electrical charge signal, which is then transmitted to an external signal conditioning circuit via a 5-axis support. When the mechanical state of the power equipment changes, the vibration signal sensed by the embedded integrated sensor changes accordingly. Subsequent signal processing compares the differences in vibration signals before and after a mechanical fault to detect mechanical faults in dry-type transformers.
[0043] b. Insulation Defect Detection Based on High-Frequency Ultrasonic Signals. When insulation defects exist inside a dry-type transformer, this location is a weak point in the insulation, prone to partial discharge during high-voltage operation. Around the partial discharge, charged particles move at high speed under the influence of an electric field, colliding with insulating material molecules and rapidly releasing energy. This causes a sharp increase in the local temperature of the surrounding dielectric material, inducing microscopic thermal expansion. The pressure waves generated by this thermal expansion propagate through the dielectric in the form of ultrasonic waves. The ultrasonic signal generated by the partial discharge propagates through the insulating epoxy resin, windings, core, and air of the dry-type transformer to a pre-set embedded integrated sensor. Matching layer 1 reduces the acoustic impedance gradient between the fastening bolts and the piezoelectric sensitive material, minimizing the attenuation of the ultrasonic signal due to reflection and refraction. The piezoelectric sensitive material achieves a sensitive response to ultrasonic signals at the resonant frequency, converting the high-frequency ultrasonic signal into an electrical signal based on the positive piezoelectric effect, and transmitting it to the subsequent signal processing circuit via an axial support. Compared to external ultrasonic sensors, using an embedded integrated broadband sensor structure improves the sensitivity of the ultrasonic detection section.
[0044] When a dry-type transformer is operating normally, the embedded broadband sensor only receives vibration signals characteristic of normal operation, such as a dominant frequency of 100Hz. When the dry-type transformer has only mechanical faults, the embedded broadband sensor only receives vibration signals indicating mechanical faults, such as changes in the dominant frequency or a rightward shift in the frequency. When the dry-type transformer has only partial discharge, the sensor receives a superposition of low-frequency vibration signals (dominant frequency 100Hz, consistent with vibration signals under normal operation) and high-frequency ultrasonic signals. By detecting the high-frequency signals, partial discharge in the dry-type transformer can be identified. When the dry-type transformer has combined electromechanical defects, the sensor receives a superposition of low-frequency vibration signals (the dominant frequency may change, with a rightward shift in the frequency, consistent with vibration signals from transformers with mechanical faults) and high-frequency ultrasonic signals.
[0045] In summary, implementing the embodiments of the present invention has the following beneficial effects:
[0046] The integrated sensor and electromechanical condition detection method for dry-type transformers provided by this invention can simultaneously measure broadband vibration signals at the same location and time, achieving mechanical integration (embedded inside the fastening bolts), electrical integration (pre-cast sensing modules), and data integration (unified time scale). This enables dry-type transformers to evolve from "passive power supply equipment" to "self-sensing intelligent nodes," providing key technical support for the digitalization of distribution networks.
[0047] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.
Claims
1. An integrated sensor for dry-type transformers, characterized in that, include: A bolt, which can be installed on the dry-type transformer, has an internal cavity. The bolt serves as the housing of the integrated sensor and is grounded by connecting to a clamp installed on the dry-type transformer. A matching layer is disposed within the cavity, and a piezoelectric sensitive element is disposed on the matching layer; An electrode layer is respectively disposed on the upper and lower surfaces of the piezoelectric sensitive element, and a steering column is disposed on the piezoelectric sensitive element; the bottom end of the steering column is perpendicular to the piezoelectric sensitive element, and the top end of the steering column is connected to the upper surface of the bolt and is provided with an output port. The matching layer is used as a base for a low-frequency vibration sensor or a high-frequency ultrasonic sensor. The electrode layer includes a piezoelectric material and metal electrodes laid on its upper and lower surfaces, used to extract the charge signal induced by the piezoelectric material under the influence of the electromechanical state of the equipment; The steering strut is used to extract the collected broadband vibration signal; The output port is used to connect to subsequent signal conditioning circuits to achieve wideband vibration signal processing and analysis.
2. The integrated sensor as described in claim 1, characterized in that, A backing is also provided on the inner wall of the cavity, and the backing is respectively arranged adjacent to the matching layer, the piezoelectric sensitive element and the steering pillar.
3. The integrated sensor as described in claim 2, characterized in that, A mass block is also provided inside the cavity, and the mass block is used to fill the space inside the cavity.
4. The integrated sensor as described in claim 1, characterized in that, The clamp includes at least an upper clamp and a lower clamp, which are respectively disposed on the upper and lower sides of the bolt for fixing the bolt; the upper clamp on the same side or the lower clamp on the same side share a signal conditioning circuit, and a wireless transmission module is provided inside the clamp for signal transmission.
5. The integrated sensor as described in claim 4, characterized in that, The signal conditioning circuit is located on the upper or lower clamp closest to the bolt.
6. The integrated sensor as described in claim 1, characterized in that, The bolts include at least winding fastening bolts, wherein the upper or lower end of the winding of the winding fastening bolts respectively shares a signal conditioning circuit.
7. A method for detecting the electromechanical condition of a dry-type transformer, implemented using an integrated sensor as described in any one of claims 1-6, characterized in that, include: The vibration signal of the dry-type transformer is detected by the piezoelectric sensitive element, wherein the vibration signal includes at least the low-frequency vibration signal change of the overall system caused by mechanical loosening and the high-frequency signal of partial discharge caused by insulation defects; The vibration signal is converted into a charge signal and transmitted to an external signal conditioning circuit; the difference between the vibration signals before and after the mechanical fault is judged based on the change of the vibration signal, and the mechanical fault detection of dry-type transformer is realized.