On-load tap-changer detection method, electronic equipment and piezoelectric sensor

Abstract

The embodiment of the invention provides an on-load tap-changer detection method, electronic equipment and a piezoelectric sensor. The method comprises the following steps: calculating internal pressure generated by a preset piezoelectric crystal in the piezoelectric sensor; calculating a resistance change rate in a Wheatstone bridge preset in a piezoresistive semiconductor film on the upper side of the piezoelectric sensor based on the internal pressure; calculating a differential voltage signal based on the resistance change rate; current state information of the on-load tap-changer is determined according to the differential voltage signal and a preset threshold value, the state information comprises whether the on-load tap-changer is abnormal or not and a current abnormal type of the on-load tap-changer, and the preset threshold value comprises a first threshold value associated with a partial discharge state and a second threshold value associated with a vibration state; the first threshold is far greater than the second threshold. Therefore, whether the on-load tap-changer is abnormal or not can be monitored more comprehensively and efficiently, and the current abnormal state of the on-load tap-changer can be accurately determined.

Description

Technical Field

[0001] The present disclosure relates to the electrical field, and in particular, to a method for detecting an on-load tap changer, an electronic device, and a piezoelectric sensor. Background Art

[0002] As the only movable key component in a power transformer, the operating state of the on-load tap changer of a converter transformer is directly related to the safety of power equipment and the reliable operation of the power grid. Conducting condition monitoring on the on-load tap changer, especially vibration and partial discharge detection, is crucial for timely discovering potential faults and ensuring the stability of the power system.

[0003] In related technologies, generally, a vibration sensor and a partial discharge detection technology are combined to detect the vibration and partial discharge of the on-load tap changer. However, using different detection devices to detect the vibration and partial discharge of the on-load tap changer respectively not only increases the detection cost and time, but also makes it difficult to achieve comprehensive and real-time condition monitoring of the on-load tap changer. It is difficult to effectively fuse and analyze the data between different detection devices, resulting in low data processing accuracy. Summary of the Invention

[0004] The on-load tap changer detection method, electronic device, and piezoelectric sensor provided by the embodiments of the present disclosure are used to achieve integrated detection of the vibration and partial discharge of the on-load tap changer, so as to more comprehensively and efficiently monitor the operating state effect of the on-load tap changer.

[0005] In a first aspect, an embodiment of the present disclosure provides an on-load tap changer detection method, including:

[0006] Calculating the internal pressure generated by a preset piezoelectric crystal in a piezoelectric sensor, where the internal pressure is generated by the piezoelectric crystal through a piezoelectric reaction based on the partial discharge and / or vibration of the on-load tap changer;

[0007] Calculating the resistance change rate in a preset Wheatstone bridge in a piezoresistive semiconductor film on the upper side of the piezoelectric sensor based on the internal pressure;

[0008] Calculating a differential voltage signal based on the resistance change rate;

[0009] Determining the current state information of the on-load tap changer according to the differential voltage signal and a preset threshold, where the state information includes whether the on-load tap changer has an abnormality and the current abnormality type of the on-load tap changer, and the preset threshold includes a first threshold associated with the partial discharge state and a second threshold associated with the vibration state, and the first threshold is much larger than the second threshold.

[0010] In a possible implementation, the Wheatstone bridge includes a first resistor, a second resistor, a third resistor, and a fourth resistor; the first resistor and the third resistor are respectively disposed on two sides in a first direction of the piezoresistive semiconductor film; the second resistor and the fourth resistor are respectively disposed on two sides in a second direction of the piezoresistive semiconductor film; the included angle between the first direction and the second direction is 90 degrees;

[0011] Calculating the resistance change rate in the preset Wheatstone bridge in the piezoresistive semiconductor film on the upper side of the piezoelectric sensor based on the internal pressure includes:

[0012] Calculating the first resistance change rate corresponding to the first resistor and the third resistor based on the first proportional relationship between the first resistor and the third resistor in the first direction, the internal pressure, a preset resistivity adjustment coefficient, and an effective area ratio coefficient;

[0013] Calculating the second resistance change rate corresponding to the second resistor and the fourth resistor based on the second proportional relationship between the second resistor and the fourth resistor in the second direction, the internal pressure, a preset resistivity adjustment coefficient, and an effective area ratio coefficient;

[0014] Wherein, the effective area ratio coefficient is the ratio of the contact area between the piezoelectric crystal and the piezoresistive semiconductor film to the piezoelectric sensor.

[0015] In a possible implementation, calculating the differential voltage signal based on the resistance change rate includes:

[0016] Performing data processing on the first resistance change rate, the second resistance change rate, and a preset supply voltage according to a preset formula to obtain the differential voltage signal;

[0017] The preset formula is used to represent the relationship between the output voltage of the Wheatstone bridge and the resistance change in the piezoresistive semiconductor film.

[0018] In a possible implementation, determining the current state information of the on-load tap-changer according to the differential voltage signal and a preset threshold includes:

[0019] Performing an amplification operation on the differential voltage signal through a preset voltage amplifier to obtain an amplified signal;

[0020] Controlling a preset data acquisition card to perform a sampling operation on the amplified signal according to a preset sampling frequency, and converting the collected amplified signal into a digital signal;

[0021] Comparing the digital signal with the preset threshold, and determining the current state information of the on-load tap-changer based on the comparison result.

[0022] In a possible implementation manner, determining the current state information of the on-load tap-changer based on the comparison result includes:

[0023] Determining a preset threshold that satisfies a preset condition for the difference from the digital signal among the first threshold and the second threshold as the current target threshold;

[0024] In response to the digital signal being greater than the target threshold, determining that the on-load tap-changer is abnormal;

[0025] Determining the state type associated with the target threshold and determining the state type as the abnormal type.

[0026] In a second aspect, an embodiment of the present disclosure provides a piezoelectric sensor, including a storage cavity made of glass, a substrate, a piezoelectric crystal, and a piezoresistive semiconductor film;

[0027] Wherein, the bottom of the storage cavity is fixed on the substrate, and the substrate is placed on the on-load tap-changer;

[0028] The piezoelectric crystal is arranged in the storage cavity, and the piezoelectric crystal is used to generate mechanical deformation based on piezoelectric reaction and generate internal pressure when partial discharge and / or vibration occur in the on-load tap-changer;

[0029] The piezoresistive semiconductor film covers the upper side of the piezoelectric crystal, and a Wheatstone bridge is arranged in the piezoresistive semiconductor film;

[0030] The resistance value of a preset resistor in the Wheatstone bridge changes with the internal pressure, and the differential voltage signal formed by the change in the resistance value is used to detect whether the on-load tap-changer is abnormal;

[0031] The storage cavity is of a hourglass cavity structure;

[0032] The piezoelectric sensor is also communicatively connected to a preset voltage amplifier, and the voltage amplifier is used to perform an amplification operation on the differential voltage signal.

[0033] In a possible implementation manner, the length of the opening side of the hourglass cavity structure is a first length, the length of the converging side of the hourglass cavity structure is a second length, and the first length is greater than the second length;

[0034] The length of the piezoresistive semiconductor film is the same as the length of the opening side of the hourglass cavity structure;

[0035] The width of the piezoelectric crystal is the same as the length of the converging side of the hourglass cavity structure.

[0036] In a possible implementation, the piezoresistive semiconductor film includes four sides, and the Wheatstone bridge includes a first resistor, a second resistor, a third resistor, and a fourth resistor;

[0037] Wherein, the first resistor, the second resistor, the third resistor, and the fourth resistor are respectively arranged on each side of the piezoresistive semiconductor film;

[0038] The first resistor and the third resistor are respectively arranged on two sides in the first direction of the piezoresistive semiconductor film, and are in a zigzag shape;

[0039] The second resistor and the fourth resistor are respectively arranged on two sides in the second direction of the piezoresistive semiconductor film, and are in a straight line shape;

[0040] The included angle between the first direction and the second direction is 90 degrees.

[0041] In a possible implementation, the voltage amplifier is communicatively connected to a preset data acquisition card;

[0042] Wherein, the data acquisition card is configured to collect the differential voltage signal according to a preset sampling frequency, convert the differential voltage signal into a digital signal, and transmit the digital signal to a preset data processing device for local discharge and / or vibration analysis operations.

[0043] In a third aspect, an embodiment of the present disclosure provides an electronic device, including: a memory, a processor;

[0044] The memory stores computer-executable instructions;

[0045] The processor executes the computer-executable instructions stored in the memory, so that the processor executes the above first aspect and / or various possible implementation manners of the first aspect.

[0046] The on-load tap-changer detection method, electronic device, and piezoelectric sensor provided by the embodiments of the present disclosure, when the on-load tap-changer generates vibration or partial discharge signals, these signals will cause the piezoelectric crystals inside the piezoelectric sensor to deform and generate internal pressure. After the internal pressure is transmitted to the piezoresistive semiconductor film, it will break the balance state of the Wheatstone bridge, so that the bridge outputs a differential voltage signal. By collecting the differential voltage signal output by the piezoelectric sensor, it is possible to accurately identify whether there is a risk of abnormality in the on-load tap-changer. Description of the Drawings

[0047] The drawings here are incorporated into the specification and constitute a part of this specification, showing the embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure.

[0048] Figure 1Schematic flowchart of the on-load tap changer detection method provided by an embodiment of the present disclosure;

[0049] Figure 2 Schematic flowchart of the on-load tap changer detection method provided by another embodiment of the present disclosure;

[0050] Figure 3 Schematic cross-sectional view of the structure of the piezoelectric sensor provided by an embodiment of the present disclosure;

[0051] Figure 4 Schematic diagram of the structure of the storage cavity made of glass provided by an embodiment of the present disclosure;

[0052] Figure 5 Top view of the structure of the piezoresistive semiconductor film provided by an embodiment of the present disclosure;

[0053] Figure 6 Schematic diagram of the structure of the electronic device provided by an embodiment of the present disclosure.

[0054] Through the above-mentioned drawings, specific embodiments of the present disclosure have been shown, and more detailed descriptions will be given later. These drawings and textual descriptions are not intended to limit the scope of the concept of the present disclosure in any way, but to illustrate the concept of the present disclosure to those skilled in the art by referring to specific embodiments. Detailed Description of Specific Embodiments

[0055] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0056] First, the terms related to the present disclosure will be explained:

[0057] On-Load Tap Changer (OLTC for short): An important device used in power transformers. It can adjust the turns ratio of the transformer under the condition that the transformer is operating with load, thereby regulating the output voltage. It is an essential key device in power transformers and can dynamically adjust the turns ratio under load to ensure voltage stability;

[0058] Wheatstone Bridge: A circuit used for precise measurement of resistance. By the principle of balancing the bridge, it can measure the unknown resistance value with high precision. Its structure is simple and the principle is clear, and it is widely used in scientific experiments and engineering fields.

[0059] Piezoelectric Crystal: It is a type of crystal material with piezoelectric effect, which can generate electric charges under mechanical stress (direct piezoelectric effect), or deform under the action of an electric field (converse piezoelectric effect) to form internal pressure;

[0060] Piezoresistive Semiconductor Film: It is a thin film material based on piezoresistive effect, which can change its resistance value when subjected to mechanical stress. This property makes it widely used in devices such as pressure sensors, accelerometers, and strain gauges.

[0061] As the only movable key component in a power transformer, the operating state of the on-load tap-changer is directly related to the safety of power equipment and the reliable operation of the power grid. Conducting condition monitoring on the on-load tap-changer, especially vibration and partial discharge detection, is crucial for timely discovering potential faults and ensuring the stability of the power system. However, there are many limitations in the current detection technologies for on-load tap-changers:

[0062] Traditional vibration detection methods mostly use ordinary vibration sensors, and the sensitivity of such sensors is limited, making it difficult to accurately capture the weak vibration signals generated during the operation of the on-load tap-changer.

[0063] Existing partial discharge detection technologies usually require the use of complex and expensive equipment, such as detection devices based on principles such as ultrasonic waves and ultra-high frequencies. These devices are not only costly but also complex to operate and have high professional requirements for the detection personnel. In addition, due to the susceptibility of partial discharge signals to external interference, the stability and reliability of the detection results face great challenges in practical applications.

[0064] Using different detection devices to detect the vibration and partial discharge of the on-load tap-changer respectively not only increases the detection cost and time, but also makes it difficult to achieve comprehensive and real-time condition monitoring of the on-load tap-changer. The data between different detection devices is difficult to effectively fuse and analyze, and cannot provide comprehensive and accurate basis for the operation and maintenance of the equipment.

[0065] In the process of solving the above technical problems, the inventor found through research that a piezoelectric sensor for realizing integrated detection of vibration and partial discharge can be set, and the operating state of the on-load tap-changer is detected based on this piezoelectric sensor, and the abnormal type is determined based on the differential voltage signal output by the piezoelectric sensor and a preset threshold.

[0066] The piezoelectric sensor at least includes a piezoelectric crystal and a piezoresistive semiconductor film. When there is vibration or partial discharge in the on-load tap-changer, the mechanical vibration will cause the piezoelectric crystal to undergo mechanical deformation, thereby generating internal pressure. A piezoresistive semiconductor film is arranged on the upper side of the piezoelectric crystal, and the internal pressure can be evenly transmitted to the piezoresistive semiconductor film. A Wheatstone bridge is arranged in the piezoresistive semiconductor film. After the internal pressure is transmitted to the piezoresistive semiconductor film, the internal pressure will break the balance state of the Wheatstone bridge, so that the Wheatstone bridge outputs a differential voltage signal. Therefore, it is possible to accurately determine whether there is a risk of abnormality in the on-load tap-changer based on the differential voltage signal and a preset threshold.

[0067] Among them, the preset threshold may include a first threshold associated with the partial discharge state and a second threshold associated with the vibration state. Therefore, the current abnormal type of the on-load tap-changer can be accurately determined according to the state type associated with the target threshold matched by the differential voltage signal.

[0068] The following uses specific embodiments to elaborate in detail on the technical solutions of the present disclosure and how the technical solutions of the present disclosure solve the above technical problems. These several specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present disclosure will be described below in conjunction with the drawings.

[0069] Figure 1 It is a schematic flowchart of the on-load tap-changer detection method provided by the embodiment of the present disclosure, which is applied to a piezoelectric sensor, as Figure 1 shown, the method includes:

[0070] Step 101, calculate the internal pressure generated by a preset piezoelectric crystal in the piezoelectric sensor, where the internal pressure is generated by the piezoelectric crystal based on the partial discharge and / or vibration of the on-load tap-changer to generate a piezoelectric reaction.

[0071] Step 102, calculate the resistance change rate in a preset Wheatstone bridge in the piezoresistive semiconductor film on the upper side of the piezoelectric sensor based on the internal pressure.

[0072] Step 103, calculate a differential voltage signal based on the resistance change rate.

[0073] Step 104, determine the current state information of the on-load tap-changer according to the differential voltage signal and a preset threshold, where the state information includes whether the on-load tap-changer has an abnormality and the current abnormal type of the on-load tap-changer, the preset threshold includes a first threshold associated with the partial discharge state and a second threshold associated with the vibration state, and the first threshold is much larger than the second threshold.

[0074] In this embodiment, the vibration and partial discharge of the on-load tap-changer can be detected based on a preset piezoelectric sensor to determine whether the on-load tap-changer is abnormal.

[0075] Optionally, the piezoelectric sensor can be arranged on the on-load tap-changer. Once the on-load tap-changer generates vibration or partial discharge signals, these signals will cause the piezoelectric crystal to undergo tensile or compressive deformation. According to the piezoelectric effect, this deformation will cause polarization and lattice displacement inside the crystal, generating internal pressure. Therefore, the internal pressure generated by the preset piezoelectric crystal in the piezoelectric sensor can be calculated.

[0076] This internal pressure can be evenly transmitted to the piezoresistive semiconductor film. A Wheatstone bridge is arranged inside the piezoresistive semiconductor film. This internal pressure acts on the piezoresistive semiconductor film through internal transmission, thereby causing a change in the resistance value of the resistors inside the Wheatstone bridge. Therefore, the resistance change rate inside the preset Wheatstone bridge in the piezoresistive semiconductor film on the upper side of the piezoelectric sensor can be calculated based on the internal pressure.

[0077] Furthermore, after determining the resistance change rate, the differential voltage signal can be accurately calculated based on the resistance change rate. Therefore, it is determined whether the on-load tap-changer is abnormal according to the differential voltage signal.

[0078] Optionally, a preset threshold can be set in advance, where the preset threshold includes a first threshold associated with the partial discharge state and a second threshold associated with the vibration state. After obtaining the differential voltage signal, the differential voltage signal can be compared with the first threshold and the second threshold respectively. It is determined whether the on-load tap-changer is abnormal based on the comparison result.

[0079] Optionally, the frequencies corresponding to partial discharge and vibration have a large gap. Therefore, the first threshold can be much larger than the second threshold. After obtaining the differential voltage signal, the preset threshold matching the differential voltage signal can be determined, and the differential voltage signal is compared with its associated preset threshold. It is determined whether the on-load tap-changer is abnormal based on the comparison result.

[0080] If the on-load tap-changer is abnormal, the current abnormal type can be determined based on its associated preset threshold. Among them, the abnormal type includes the partial discharge state type and the vibration state type.

[0081] For the on-load tap-changer detection method provided by the embodiments of the present disclosure, when the on-load tap-changer generates vibration or partial discharge signals, these signals will cause the piezoelectric crystal inside the piezoelectric sensor to deform, generating internal pressure. After the internal pressure is transmitted to the piezoresistive semiconductor film, it will break the balanced state of the Wheatstone bridge, so that the bridge outputs a differential voltage signal. By collecting the differential voltage signal output by the piezoelectric sensor, it is possible to accurately identify whether there is a risk of abnormality in the on-load tap-changer.

[0082] In addition, by setting a first threshold and a second threshold, it is possible to further determine the current type of abnormality on the basis of accurately identifying whether there is an abnormality in the on-load tap changer.

[0083] Further, on the basis of any of the above embodiments, the Wheatstone bridge includes a first resistor, a second resistor, a third resistor, and a fourth resistor. The first resistor and the third resistor are respectively disposed on two sides in a first direction of the piezoresistive semiconductor film. The second resistor and the fourth resistor are respectively disposed on two sides in a second direction of the piezoresistive semiconductor film. The included angle between the first direction and the second direction is 90 degrees.

[0084] Step 102 includes:

[0085] Calculate a first resistance change rate corresponding to the first resistor and the third resistor based on a first proportional relationship between the first resistor and the third resistor in the first direction, the internal pressure, a preset resistivity adjustment coefficient, and an effective area ratio coefficient.

[0086] Calculate a second resistance change rate corresponding to the second resistor and the fourth resistor based on a second proportional relationship between the second resistor and the fourth resistor in the second direction, the internal pressure, a preset resistivity adjustment coefficient, and an effective area ratio coefficient.

[0087] Wherein, the effective area ratio coefficient is the ratio of the contact area between the piezoelectric crystal and the piezoresistive semiconductor film to the piezoelectric sensor.

[0088] In this embodiment, the Wheatstone bridge includes a first resistor, a second resistor, a third resistor, and a fourth resistor. The first resistor and the third resistor are respectively disposed on two sides in a first direction of the piezoresistive semiconductor film. The second resistor and the fourth resistor are respectively disposed on two sides in a second direction of the piezoresistive semiconductor film. The included angle between the first direction and the second direction is 90 degrees.

[0089] When the on-load tap changer of the converter transformer operates normally, the sensor is in a stable state, and the voltage signal output by the Wheatstone bridge remains stable. Once the on-load tap changer generates a vibration or partial discharge signal, these signals will cause the piezoelectric crystal to deform, so the piezoelectric crystal generates an internal pressure. This internal pressure can be uniformly transmitted to the piezoresistive semiconductor film. At this time, it will cause a change in the resistance on the piezoresistive film. This change in resistivity will break the balance state of the Wheatstone bridge, thereby causing the bridge to output a differential voltage signal.

[0090] Optionally, when a vibration signal is generated, the piezoelectric crystal undergoes strain , A is the vibration amplitude, f is the vibration frequency, and g is the acceleration of gravity. The strain of the piezoelectric crystal causes the pressure on the piezoresistive film to change. ,in is the elastic stiffness constant of the piezoelectric crystal.

[0091] The electric field generated by partial discharge causes the piezoelectric crystal to stretch or compress. According to the piezoelectric effect, this deformation causes polarization and lattice displacement inside the crystal, which in turn causes pressure changes on the crystal surface. This pressure is transmitted internally and acts on the piezoresistive semiconductor film. ,in is the piezoelectric constant, and E is the local discharge field intensity.

[0092] Since the four sensing elements in the Wheatstone bridge, the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4, have different positions and orientations, the stress and strain they sense are also different. With the symmetrical distribution of strain, the resistivity change of R1 and R3 is the same, defined as ΔR 1,3 Similarly, the resistivity change of R2 and R4 is defined as ΔR 2,4 Assuming that the four sensing elements are placed at the center of each side and are regarded as particles, the first resistance change rate and the second resistance change rate can be calculated using Formula 1-2.

[0093] (1)

[0094] (2)

[0095] in, is a first proportional relationship between the first resistor and the third resistor arranged in the first direction, is the second ratio between the second resistance and the fourth resistance in the second direction. The first direction (L direction) is defined as the center of a side pointing toward the center of the square, while the second direction (T direction) is defined as the perpendicular direction within the plane. The L and T directions for each sensor element are different along the xy axes. P(N,T) ranges from 0 to 1 and is the adjustment coefficient for the piezoresistivity, which depends on the semiconductor doping density N and the operating temperature T. The coefficient k represents the effective area ratio, which characterizes the ratio of the active area to the entire sensor element. This is the internal pressure generated inside the piezoelectric crystal by vibration or partial discharge, calculated based on the above formula.

[0096] Furthermore, based on any of the above embodiments, step 103 includes:

[0097] The first resistance change rate, the second resistance change rate, and a preset power supply voltage are processed according to a preset formula to obtain the differential voltage signal.

[0098] The preset formula is used to represent the relationship between the output voltage of the Wheatstone bridge and the change in the internal resistance of the piezoresistive semiconductor film.

[0099] In this embodiment, after respectively determining the first resistance change rate and the second resistance change rate corresponding to the Wheatstone bridge, data processing can be performed on the first resistance change rate, the second resistance change rate, and the preset power supply voltage according to the preset formula to obtain a differential voltage signal.

[0100] The preset formula is used to represent the relationship between the output voltage of the Wheatstone bridge and the change in the internal resistance of the piezoresistive semiconductor film. The preset formula is as shown in Formula 3:

[0101] (3)

[0102] Wherein, U s is the power supply voltage.

[0103] The on-load tap-changer detection method provided by the embodiments of the present disclosure can, by respectively calculating the first resistance change rate and the second resistance change rate corresponding to the Wheatstone bridge, determine a differential voltage signal based on the resistance change of the Wheatstone bridge, and further accurately identify whether there is a risk of abnormality in the on-load tap-changer.

[0104] Figure 2 FIG. is a schematic flowchart of the on-load tap-changer detection method provided by another embodiment of the present disclosure. On the basis of any of the above embodiments, as Figure 2 shown, step 104 includes:

[0105] Step 201: Perform an amplification operation on the differential voltage signal through a preset voltage amplifier to obtain an amplified signal.

[0106] Step 202: Control a preset data acquisition card to sample the amplified signal according to a preset sampling frequency, and convert the sampled amplified signal into a digital signal.

[0107] Step 203: Compare the digital signal with the preset threshold, and determine the current status information of the on-load tap-changer based on the comparison result.

[0108] In this embodiment, after the differential voltage signal is collected, since the differential voltage signal is relatively weak, an external detection device needs to be connected to process the differential voltage signal. For example, a high-precision voltage amplifier is used to amplify the weak differential voltage signal output by the Wheatstone bridge to obtain an amplified signal for subsequent acquisition and analysis. The preset data acquisition card can be controlled to collect the amplified signal at a certain sampling frequency and convert it into a digital signal. Any signal conversion method can be used to implement the conversion of the digital signal, and the present disclosure does not limit this.

[0109] Further, a preset threshold can be used to determine whether there is a risk of abnormality and the type of abnormality. The preset threshold can be an empirical value, or the preset threshold can be set by the user according to actual needs, and the present disclosure does not limit this. Therefore, the digital signal can be compared with the preset threshold, and the current state information of the on-load tap-changer can be determined based on the comparison result.

[0110] The on-load tap-changer detection method provided by the embodiments of the present disclosure can amplify the weak differential voltage signal output by the Wheatstone bridge by communicatively connecting the piezoelectric sensor and the voltage amplifier for subsequent acquisition and analysis. By converting the amplified signal into a digital signal. Therefore, the analysis operations of the vibration and partial discharge of the on-load tap-changer can be more flexibly based on the digital signal.

[0111] Further, on the basis of any of the above embodiments, step 203 includes:

[0112] Determine a preset threshold whose difference from the digital signal satisfies a preset condition among the first threshold and the second threshold as the current target threshold.

[0113] In response to the digital signal being greater than the target threshold, determine that the on-load tap-changer is abnormal;

[0114] Determine the state type associated with the target threshold and determine the state type as the abnormal type

[0115] In this embodiment, in order to accurately determine whether the on-load tap-changer is abnormal, different thresholds can be set for the vibration and partial discharge of the on-load tap-changer respectively. Thus, based on different thresholds, it can be accurately determined whether the on-load tap-changer is abnormal, and the source of the fault can also be located.

[0116] Optionally, the preset threshold includes a first threshold associated with partial discharge and a second threshold associated with vibration, and the first threshold is much larger than the second threshold. For example, the frequency band range associated with the differential voltage signal generated by vibration is generally 0-1000 hz, while the frequency band range of the differential voltage signal generated by partial discharge is generally 10-100 khz.

[0117] Since the first threshold is much larger than the second threshold, after obtaining the digital signal corresponding to the differential voltage signal, the digital signal can be compared with the first threshold and the second threshold respectively. The preset threshold whose difference from the digital signal meets the preset condition is used as the current target threshold.

[0118] After determining the target threshold, the digital signal can be compared with the target threshold to determine whether the digital signal is greater than the target threshold. If so, it indicates that the on-load tap-changer is abnormal. Otherwise, it indicates that there is no risk of abnormality in the on-load tap-changer.

[0119] Optionally, when it is determined that there is a risk of abnormality in the on-load tap-changer, the current abnormal state can be determined based on the state of the on-load tap-changer associated with the target threshold.

[0120] Meanwhile, the collected data can also be further analyzed for assistance, such as by methods like spectrum analysis to judge the frequency components and characteristics of the digital signal, so as to more accurately determine the fault type and location.

[0121] The on-load tap-changer detection method provided by the embodiments of the present disclosure can accurately determine whether the on-load tap-changer is abnormal based on the preset threshold by setting the preset threshold. And by setting two different thresholds, it can also accurately identify the cause of the current differential voltage signal based on the two different thresholds.

[0122] Figure 3 It is a schematic cross-sectional view of the structure of the piezoelectric sensor provided by the embodiments of the present disclosure, as Figure 3 shown, the piezoelectric sensor 31 includes a storage cavity 32 made of glass, a substrate 33, a piezoelectric crystal 34, and a piezoresistive semiconductor film 35.

[0123] Wherein, the bottom of the storage cavity 32 is fixed on the substrate 33, and the substrate 33 is placed on the on-load tap-changer.

[0124] The piezoelectric crystal 34 is arranged in the storage cavity 32. The piezoelectric crystal 34 is used to generate mechanical deformation based on the piezoelectric reaction and generate internal pressure when partial discharge and / or vibration occur in the on-load tap-changer.

[0125] The piezoresistive semiconductor film 35 covers the upper side of the piezoelectric crystal 34, and a Wheatstone bridge is arranged in the piezoresistive semiconductor film 35.

[0126] The resistance value of the preset resistor in the Wheatstone bridge changes with the internal pressure, and the differential voltage signal formed by the change in the resistance value is used to detect whether the on-load tap-changer is abnormal.

[0127] In this embodiment, the piezoelectric sensor 31 includes a storage cavity 32 made of glass, a substrate 33, a piezoelectric crystal 34, and a piezoresistive semiconductor film 35.

[0128] Optionally, (1 - x)[Pb(Mg 1 / 3 Nb 2 / 3 )O3] - x[PbTiO3] (PMN - PT) can be selected as the piezoelectric material, and P-type doped silicon as the piezoresistive material. PMN - PT has a large piezoelectric coefficient and good linear response characteristics. Under the action of an electric field, according to the piezoelectric equation, it can efficiently convert mechanical energy into an electrical signal. When the on-load tap-changer vibrates or partial discharge generates mechanical energy, the PMN - PT crystal generates strain. P-type doped silicon works based on the piezoresistive effect. When stressed, its resistivity changes accordingly with the stress change, and the change in pressure can be converted into a change in resistance for subsequent electrical signal processing.

[0129] The bottom of the storage cavity 32 is fixed on the substrate 33, and the substrate 33 is placed on the on-load tap-changer.

[0130] The storage cavity 32 is provided with a piezoelectric crystal 34, which is used to generate mechanical deformation based on the piezoelectric reaction and generate internal pressure when the on-load tap-changer has partial discharge and / or vibration.

[0131] The piezoresistive semiconductor film 35 covers the upper side of the piezoelectric crystal 34. When an external electric field is applied along the y-axis, the piezoelectric crystal 34 expands and contracts, causing the piezoresistive semiconductor film 35 to deform through physical contact and mechanical coupling.

[0132] When the on-load tap-changer vibrates or has partial discharge, the mechanical vibration will cause the piezoelectric crystal 34 to generate mechanical deformation, and then generate an internal pressure P. This pressure P is uniformly transmitted to the piezoresistive semiconductor film 35. Under the assumption of small deformation, according to the thin film mechanics theory, the strain distribution of the piezoresistive semiconductor film 35 can be calculated by relevant equations, such as formula (4):

[0133] Maximum stress (4)

[0134] where a is the film length, t m is the film thickness, the transverse stress , and υ is the Poisson's ratio. This strain will cause the resistance of the piezoresistive semiconductor film 35 to change, thus realizing the conversion of physical quantities.

[0135] Furthermore, a Wheatstone bridge is also provided in the piezoresistive semiconductor film 35. The resistance value of the resistors in the Wheatstone bridge changes with the internal pressure, and the differential voltage signal formed by the change in the resistance value is used to detect whether there is an abnormality in the on-load tap-changer. Among them, the resistor can be a piezoresistive sensing element. The resistance value of the piezoresistive sensing element can change with the pressure.

[0136] When the on-load tap-changer of the converter transformer operates normally, the sensor is in a stable state, and the voltage signal output by the Wheatstone bridge remains stable. Once the on-load tap-changer generates vibration or partial discharge signals, these signals will cause the piezoelectric crystal to deform, generating internal pressure. After the internal pressure is transmitted to the piezoresistive semiconductor film, it will break the balance state of the Wheatstone bridge, so that the bridge outputs a differential voltage signal. Furthermore, it is possible to accurately determine whether there is an abnormal risk in the on-load tap-changer based on this differential voltage signal.

[0137] In addition, a sensing chip is also provided on the piezoresistive semiconductor film. The sensing chip is used to convert physical quantities into electrical signals for subsequent data processing. For example, the sensing chip can convert the differential voltage signal output by the Wheatstone bridge into an electrical signal. So as to determine whether there is an abnormality in the on-load tap-changer based on this electrical signal subsequently.

[0138] The piezoelectric sensor provided by the embodiment of the present disclosure, by arranging a piezoelectric crystal in the glass cavity, when the on-load tap-changer has vibration or partial discharge, the mechanical vibration will cause the piezoelectric crystal to undergo mechanical deformation, and then generate internal pressure. A piezoresistive semiconductor film is arranged on the upper side of the piezoelectric crystal, and the internal pressure can be evenly transmitted to the piezoresistive semiconductor film. A Wheatstone bridge is arranged in the piezoresistive semiconductor film. After the internal pressure is transmitted to the piezoresistive semiconductor film, the internal pressure will break the balance state of the Wheatstone bridge, so that the bridge outputs a differential voltage signal. Therefore, it is possible to accurately determine whether there is a risk of abnormality in the on-load tap-changer based on this differential voltage signal.

[0139] Figure 4 It is a schematic structural diagram of a storage cavity made of glass provided by an embodiment of the present disclosure, as Figure 4 shown, the storage cavity 41 is a hourglass-shaped cavity structure.

[0140] Among them, the length 42 of the opening side of the hourglass-shaped cavity structure is the first length (a), the length 43 of the converging side of the hourglass-shaped cavity structure is the second length (b), and the first length is greater than the second length.

[0141] The length of the piezoresistive semiconductor film is the same as the length of the opening side of the hourglass-shaped cavity structure.

[0142] The width of the piezoelectric crystal is the same as the length of the converging side of the hourglass-shaped cavity structure.

[0143] In this embodiment, the storage cavity 41 has an hourglass cavity structure. The hourglass cavity structure includes an opening side and a converging side. The length 42 of the opening side is the first length (a), and the length 43 of the converging side of the hourglass cavity structure is the second length (b), and the first length is greater than the second length. The length of the piezoresistive semiconductor film is consistent with the length of the opening side of the hourglass cavity structure. The width of the piezoelectric crystal is consistent with the length of the converging side of the hourglass cavity structure.

[0144] Optionally, in order to improve the detection accuracy and stability, the finite element method (FEM) can be used, with the help of Comsol Multiphysics software, to analyze the strain distribution, sensitivity and other performance indicators of the sensor under different film lengths a, cavity lengths, and film thicknesses t. m It can be seen from the simulation that a larger film length a helps to improve the sensitivity within a certain range, but too long may cause other problems; a smaller film thickness t m can improve the sensitivity, but factors such as the mechanical strength of the film need to be comprehensively considered. Through a large number of simulations and analyses, the optimal parameter combination is determined to ensure that the sensor can accurately detect the vibration and partial discharge signals of the on-load tap-changer in actual applications.

[0145] It should be noted that compared with the traditional cylindrical storage cavity, the use of the hourglass cavity structure can effectively reduce the volume of the piezoelectric sensor, so it is more cost-saving in the production process. In addition, the small-volume piezoelectric sensor is often more convenient and flexible to install. And because the volume of the piezoelectric sensor is small, the mass of the piezoelectric sensor is also relatively small. During the vibration monitoring process, the interference generated by the piezoelectric sensor to the vibration of the on-load tap-changer is correspondingly reduced, so the accuracy of detecting the vibration and partial discharge of the on-load tap-changer can be further improved.

[0146] The piezoelectric sensor provided by the embodiment of the present disclosure sets the storage cavity with an hourglass cavity structure, and analyzes the strain distribution, sensitivity and other performance indicators of the sensor under different film lengths a, cavity lengths, and film thicknesses t m through simulation software, and sets the piezoelectric sensor, so as to ensure that the piezoelectric sensor can accurately detect the vibration and partial discharge signals of the on-load tap-changer.

[0147] Figure 5 This is a top view of the structure of the piezoresistive semiconductor film provided by the embodiment of the present disclosure. On the basis of any of the above embodiments, as Figure 5 shown, the Wheatstone bridge includes a first resistor 51, a second resistor 52, a third resistor 53, and a fourth resistor 54.

[0148] Among them, the first resistor 51, the second resistor 52, the third resistor 53, and the fourth resistor 54 are respectively arranged on the four sides of the piezoresistive semiconductor film.

[0149] The first resistor 51 and the third resistor 53 are respectively arranged on two sides in the first direction of the piezoresistive semiconductor film, and are in a zigzag shape.

[0150] The second resistor 52 and the fourth resistor 54 are respectively arranged on two sides in the second direction of the piezoresistive semiconductor film, and are in a straight line shape.

[0151] The included angle between the first direction and the second direction is 90 degrees.

[0152] In this embodiment, the Wheatstone bridge includes a first resistor 51, a second resistor 52, a third resistor 53, and a fourth resistor 54. Among them, the first resistor 51, the second resistor 52, the third resistor 53, and the fourth resistor 54 are respectively arranged on four sides of the piezoresistive semiconductor film.

[0153] For example, the piezoresistive semiconductor film can be a rectangular semiconductor film, and electrode leads U s (+), U o (+), U s (-), U o (-) can be respectively arranged at four corner positions of the rectangle. The first resistor 51, the second resistor 52, the third resistor 53, and the fourth resistor 54 are respectively arranged on four sides of the rectangular semiconductor film.

[0154] Optionally, the first resistor 51, the second resistor 52, the third resistor 53, and the fourth resistor 54 can be respectively placed at the central positions of each side of the piezoresistive semiconductor film.

[0155] Among them, the first resistor 51 and the third resistor 53 extend in a zigzag shape in the first direction of the piezoresistive semiconductor film, while the third resistor 52 and the fourth resistor 54 are straight strips in the second direction of the piezoresistive semiconductor film. This layout utilizes the principle of symmetric strain distribution to convert the resistance change into a differential voltage signal output.

[0156] The included angle between the first direction and the second direction is 90 degrees.

[0157] For example, in the unstrained state, the resistance values of the four sensing elements are balanced with each other, all about 8.45 kΩ, so as to reduce zero drift.

[0158] The piezoelectric sensor provided by the embodiments of the present disclosure sets a Wheatstone bridge in a piezoresistive semiconductor film. When the on-load tap-changer of the transformer operates normally, the sensor is in a stable state, and the voltage signal output by the Wheatstone bridge remains stable. Once the on-load tap-changer generates vibration or partial discharge signals, these signals will cause the piezoelectric crystal to deform and generate internal pressure. After the internal pressure is transmitted to the piezoresistive semiconductor film, it will break the balance state of the Wheatstone bridge, so that the bridge outputs a differential voltage signal. Furthermore, it is possible to accurately determine whether there is a risk of abnormality in the on-load tap-changer based on the differential voltage signal.

[0159] Further, on the basis of any of the above embodiments, the piezoelectric sensor is also communicatively connected to a preset voltage amplifier, and the voltage amplifier is used to perform an amplification operation on the differential voltage signal.

[0160] In this embodiment, after the differential voltage signal is collected, since the differential voltage signal is relatively weak, in order to process the differential voltage signal, it is necessary to connect an external detection device. For example, a high-precision voltage amplifier is used to amplify the weak differential voltage signal output by the Wheatstone bridge to obtain an amplified signal for subsequent collection and analysis.

[0161] Therefore, the piezoelectric sensor is also communicatively connected to a preset voltage amplifier, so that after the differential voltage signal is collected, the voltage amplifier can amplify the weak differential voltage signal output by the Wheatstone bridge to obtain an amplified signal.

[0162] The piezoelectric sensor provided by the embodiments of the present disclosure can amplify the weak differential voltage signal output by the Wheatstone bridge by communicatively connecting the piezoelectric sensor with a voltage amplifier, so as to facilitate subsequent collection and analysis.

[0163] Further, on the basis of any of the above embodiments, the voltage amplifier is communicatively connected to a preset data acquisition card.

[0164] Wherein, the data acquisition card is used to collect the differential voltage signal according to a preset sampling frequency, convert the differential voltage signal into a digital signal, and transmit the digital signal to a preset data processing device for analysis operations of partial discharge and / or vibration.

[0165] In this embodiment, the voltage amplifier is communicatively connected to a preset data acquisition card. It is possible to control the preset data acquisition card to collect the amplified signal output by the voltage amplifier at a certain sampling frequency and convert it into a digital signal. Among them, any signal conversion method can be used to realize the conversion of the digital signal, and the present disclosure does not limit this. Thus, it is possible to accurately perform analysis operations on the vibration and partial discharge of the on-load tap-changer based on the digital signal.

[0166] The piezoelectric sensor provided by the embodiments of the present disclosure is communicatively connected to a preset data acquisition card through a voltage amplifier, so that the acquisition operation of differential voltage signals can be realized and converted into digital signals. Therefore, the analysis operations of the vibration and partial discharge of the on-load tap changer can be more flexibly performed based on the digital signals.

[0167] Figure 6 It is a schematic structural diagram of the electronic device provided by the embodiments of the present disclosure. As Figure 6 shown, the electronic device 60 provided in this embodiment includes: at least one processor 601 and a memory 602. Optionally, the device 60 further includes a communication component 603. Among them, the processor 601, the memory 602, and the communication component 603 are connected through a bus 604.

[0168] In the specific implementation process, at least one processor 601 executes the computer-executable instructions stored in the memory 602, so that at least one processor 601 executes the above-mentioned method.

[0169] For the specific implementation process of the processor 601, reference can be made to the above method embodiment, and its implementation principle and technical effect are similar, which will not be elaborated here in this embodiment.

[0170] In the above embodiments, it should be understood that the processor may be a central processing unit (English: Central Processing Unit, abbreviated: CPU), or other general-purpose processors, digital signal processors (English: Digital Signal Processor, abbreviated: DSP), application-specific integrated circuits (English: Application Specific Integrated Circuit, abbreviated: ASIC), etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules in the processor.

[0171] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (Non-volatile Memory, NVM), such as at least one disk memory.

[0172] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the buses in the accompanying drawings of the present disclosure are not limited to only one bus or one type of bus.

[0173] The present disclosure also provides a computer program product, including a computer program which, when executed by a processor, implements the above-mentioned method.

[0174] Those of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiments can be completed by hardware related to program instructions. The foregoing program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps including the above method embodiments; and the foregoing storage medium includes: various media such as ROM, RAM, magnetic disk, or optical disc that can store program codes.

[0175] Finally, it should be noted that: After considering the specification and practicing the invention disclosed herein, those skilled in the art will readily think of other embodiments of the present invention. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include common general knowledge or conventional technical means in the technical field not disclosed in the present invention. It is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A on-load tap-changer detection method, applied to a piezoelectric sensor, characterized in that Including: Calculating the internal pressure generated by a preset piezoelectric crystal in a piezoelectric sensor, where the internal pressure is generated by the piezoelectric crystal due to partial discharge and / or vibration of a on-load tap-changer; Calculating the resistance change rate in a preset Wheatstone bridge within a piezoresistive semiconductor film on the upper side of the piezoelectric sensor based on the internal pressure; Calculating a differential voltage signal based on the resistance change rate; Determining the current state information of the on-load tap-changer according to the differential voltage signal and a preset threshold, where the state information includes whether the on-load tap-changer has an abnormality and the current abnormal type of the on-load tap-changer, and the preset threshold includes a first threshold associated with the partial discharge state and a second threshold associated with the vibration state, and the first threshold is much larger than the second threshold; 2. The method according to claim 1, characterized in that The Wheatstone bridge includes a first resistor, a second resistor, a third resistor, and a fourth resistor; the first resistor and the third resistor are respectively arranged on two sides in a first direction of the piezoresistive semiconductor film; the second resistor and the fourth resistor are respectively arranged on two sides in a second direction of the piezoresistive semiconductor film; the included angle between the first direction and the second direction is 90 degrees; The calculating the resistance change rate in the preset Wheatstone bridge within the piezoresistive semiconductor film on the upper side of the piezoelectric sensor based on the internal pressure includes: Calculating a first resistance change rate corresponding to the first resistor and the third resistor based on a first proportional relationship between the first resistor and the third resistor in the first direction, the internal pressure, a preset resistivity adjustment coefficient, and an effective area ratio coefficient; Calculating a second resistance change rate corresponding to the second resistor and the fourth resistor based on a second proportional relationship between the second resistor and the fourth resistor in the second direction, the internal pressure, a preset resistivity adjustment coefficient, and an effective area ratio coefficient; Wherein, the effective area ratio coefficient is the ratio of the contact area between the piezoelectric crystal and the piezoresistive semiconductor film to the piezoelectric sensor; 3. The method according to claim 2, characterized in that, The calculating the differential voltage signal based on the resistance change rate includes: Performing data processing on the first resistance change rate, the second resistance change rate, and a preset supply voltage according to a preset formula to obtain the differential voltage signal; The preset formula is used to represent the relationship between the output voltage of the Wheatstone bridge and the resistance change in the piezoresistive semiconductor film; 4. The method according to any one of claims 1 to 3, characterized in that, The determining the current state information of the on-load tap-changer according to the differential voltage signal and the preset threshold includes: Performing an amplification operation on the differential voltage signal through a preset voltage amplifier to obtain an amplified signal; Controlling a preset data acquisition card to sample the amplified signal according to a preset sampling frequency and converting the sampled amplified signal into a digital signal; Comparing the digital signal with the preset threshold and determining the current state information of the on-load tap-changer based on the comparison result; 5. The method according to claim 4, wherein The determining the current state information of the on-load tap-changer based on the comparison result includes: Determining a preset threshold whose difference from the digital signal satisfies a preset condition among the first threshold and the second threshold as the current target threshold; In response to the digital signal being greater than the target threshold, it is determined that the on-load tap-changer is abnormal; Determine the state type associated with the target threshold, and determine the state type as the abnormal type.

6. A piezoelectric sensor, characterized in that, It includes a storage cavity made of glass material, a substrate, a piezoelectric crystal, and a piezoresistive semiconductor film; Wherein, the bottom of the storage cavity is fixed on the substrate, and the substrate is placed on the on-load tap-changer; The piezoelectric crystal is arranged in the storage cavity, and the piezoelectric crystal is used to generate mechanical deformation based on the piezoelectric reaction and generate internal pressure when partial discharge and / or vibration occur in the on-load tap-changer; The piezoresistive semiconductor film covers the upper side of the piezoelectric crystal, and a Wheatstone bridge is arranged in the piezoresistive semiconductor film; The resistance value of the preset resistor in the Wheatstone bridge changes with the internal pressure, and the differential voltage signal formed by the change of the resistance value is used to detect whether the on-load tap-changer is abnormal; The storage cavity is of a hourglass cavity structure; The piezoelectric sensor is also communicatively connected to a preset voltage amplifier, and the voltage amplifier is used to perform an amplification operation on the differential voltage signal.

7. The piezoelectric sensor according to claim 6, characterized in that, The length of the opening side of the hourglass cavity structure is a first length, the length of the convergent side of the hourglass cavity structure is a second length, and the first length is greater than the second length; The length of the piezoresistive semiconductor film is consistent with the length of the opening side of the hourglass cavity structure; The width of the piezoelectric crystal is consistent with the length of the convergent side of the hourglass cavity structure.

8. The piezoelectric sensor according to claim 6, wherein The piezoresistive semiconductor film includes four sides, and the Wheatstone bridge includes a first resistor, a second resistor, a third resistor, and a fourth resistor; Wherein, the first resistor, the second resistor, the third resistor, and the fourth resistor are respectively arranged on each side of the piezoresistive semiconductor film; The first resistor and the third resistor are respectively arranged on two sides in the first direction of the piezoresistive semiconductor film, in a zigzag shape; The second resistor and the fourth resistor are respectively arranged on two sides in the second direction of the piezoresistive semiconductor film, in a straight line shape; The included angle between the first direction and the second direction is 90 degrees.

9. The piezoelectric sensor according to any one of claims 6-8, characterized in that, The voltage amplifier is communicatively connected to a preset data acquisition card; Wherein, the data acquisition card is used to collect the differential voltage signal according to a preset sampling frequency, convert the differential voltage signal into a digital signal, and transmit the digital signal to a preset data processing device for analysis operations of partial discharge and / or vibration.

10. An electronic device, characterized in that, It includes: A memory, a processor; The memory stores computer execution instructions; The processor executes the computer execution instructions stored in the memory, so that the processor executes the method according to any one of claims 1-5.

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