CN110426614B - Ultrasonic partial discharge sensor designed by high-precision signal frequency reduction circuit - Google Patents
Ultrasonic partial discharge sensor designed by high-precision signal frequency reduction circuit Download PDFInfo
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- CN110426614B CN110426614B CN201910802730.6A CN201910802730A CN110426614B CN 110426614 B CN110426614 B CN 110426614B CN 201910802730 A CN201910802730 A CN 201910802730A CN 110426614 B CN110426614 B CN 110426614B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1209—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing using acoustic measurements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/14—Circuits therefor, e.g. for generating test voltages, sensing circuits
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Abstract
The invention discloses an ultrasonic partial discharge sensor designed by a high-precision signal frequency reducing circuit, which comprises the high-precision signal frequency reducing circuit, wherein the high-precision signal frequency reducing circuit comprises a detection circuit and a filter circuit which are electrically connected, and the detection circuit comprises a first resistor R1, a second resistor R2, a third resistor R3, a first diode D1, a second diode D2, a first capacitor C1 and a second capacitor C2; the filter circuit comprises a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5 and an operational amplifier A. The ultrasonic partial discharge sensor designed by the high-precision signal frequency reduction circuit provided by the invention has the advantages of high-precision special signal frequency reduction circuit, simple circuit structure, consideration of small signal and large signal processing, and capability of greatly improving the detection precision and detection sensitivity of partial discharge.
Description
Technical Field
The invention relates to the technical field of circuit design of ultrasonic partial discharge sensors, in particular to an ultrasonic partial discharge sensor designed by a high-precision signal frequency reduction circuit.
Background
At present, low-voltage switch cabinets in power plants and transformer substations are numerous in number, the operating environment is severe, and internal elements are easy to age, so that the phenomenon of partial discharge is caused. The partial discharge is a discharge which occurs between the electrodes but does not penetrate through the two electrodes, and is a phenomenon of repeated breakdown and extinction under the action of high electric field intensity due to defects in equipment insulation or defects caused in the production process.
The discharge capability is very small, so that the short-term existence of the discharge does not affect the insulation strength of the electrical equipment, but if partial discharge occurs continuously in the electrical equipment under the insulation voltage, the weak discharge can accumulate the effect to gradually degrade the dielectric property of the insulation and expand local defects to finally cause the whole insulation breakdown, and although the partial discharge can degrade the insulation to cause damage, the development of the discharge requires a certain time, so that the partial discharge tester needs to be used regularly to measure the partial discharge. The most widespread solution for detecting partial discharge is to install an ultrasonic partial discharge sensor. The core of the ultrasonic partial discharge sensor is a hardware part, and the most important circuit of the hardware part is a signal frequency reduction circuit.
The existing signal frequency-reducing circuit in the ultrasonic partial discharge detection is mainly divided into the following parts: first, an envelope detection circuit, which is a diode detection circuit, such as a series detection circuit, a parallel detection circuit, a voltage doubler detection circuit, and a peak detection circuit, is often used as an envelope detection method; and secondly, a filter circuit adopts a low-order passive filter. However, in the prior art, the detection circuit has poor implementation effect, is easy to generate inertia distortion negative peak cutting distortion, and simultaneously introduces noise; the series diode envelope detection is suitable for large signal peak detection, the detection of small signals cannot be carried out, active elements such as an operational amplifier and the like need to be added in a peak detection circuit, the requirement on operational amplification is high, and meanwhile, the cost of the device is increased; the traditional filter circuit has a small dynamic response range and cannot process small signals and large signals at the same time; the passband amplification factor and the cut-off frequency of the traditional passive filter circuit are changed along with the load, so that the traditional passive filter circuit is not suitable for occasions with high signal processing requirements, and meanwhile, the passband of the traditional filter is also influenced by the input resistance and the output resistance, namely the internal resistance of an input end signal source can shift the resonance point of a filter network, so that the filtering effect is reduced; the overall signal is subjected to large external interference, so that the sensitivity of the detection device is low.
Disclosure of Invention
The invention aims to provide an ultrasonic partial discharge sensor designed by a high-precision signal frequency reduction circuit, which is provided with a high-precision special signal frequency reduction circuit, has a simple circuit structure, gives consideration to small-signal and large-signal processing and can greatly improve the detection precision and the detection sensitivity of partial discharge.
In order to achieve the purpose, the invention provides the following scheme:
an ultrasonic partial discharge sensor designed by a high-precision signal frequency reduction circuit comprises the high-precision signal frequency reduction circuit, wherein the high-precision signal frequency reduction circuit comprises a detection circuit and a filter circuit which are electrically connected, the detection circuit comprises a first resistor R1, a second resistor R2, a third resistor R3, a first diode D1, a second diode D2, a first capacitor C1 and a second capacitor C2, one end of the first resistor R1 is connected with a signal input end, the other end of the first resistor R1 is grounded, one end of the first diode D1 is connected with the detection signal input end, the other end of the first diode D1 is connected with one end of the second resistor R2, the other end of the second resistor R2 is grounded, the first capacitor C1 is connected with the second resistor R2 in parallel, one end of the second capacitor C2 is connected with a non-grounded end of the first capacitor C1, and the other end of the second capacitor C2 is connected with one end of the second diode D2, the other end of the second diode D2 is grounded, the third resistor R3 is connected in parallel with the second diode D2, and the non-grounded end of the third resistor R3 is connected to the detection signal output end; the detection signal output end is connected with the filtering signal input end;
the filter circuit comprises a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5 and an operational amplifier A, wherein the fourth resistor R4 and the fifth resistor R5 are connected in series to form a first branch, one end of the first branch is connected with the filter signal input end, the third capacitor C3 and the fourth capacitor C4 are connected in series to form a second branch, and the second branch is connected with the positive input end of the operational amplifier A after being connected with the first branch in parallel; one end of the sixth resistor R6 is connected to the front of the third capacitor C3 and the fourth capacitor C4, and the other end is grounded; one end of the fifth capacitor C5 is connected between the fourth resistor R4 and the fifth resistor R5, the other end is connected to the output end of the operational amplifier a, one end of the fourth resistor R7 is connected to the positive input end of the operational amplifier a, the other end is grounded, one end of the sixth capacitor C6 is connected to the positive input end of the operational amplifier a, and the other end is grounded; one end of the eighth resistor R8 is connected to the inverting input end of the operational amplifier A, and the other end is grounded; one end of the ninth resistor R9 is connected to the inverting input terminal of the operational amplifier a, and the other end is connected to the output terminal of the operational amplifier a.
Optionally, the circuit elements of the filter circuit have the following value relationship:
let the median values a, b, c be as follows:
wherein Q represents the quality factor of the circuit, f0Representing the aggregate center frequency, f, of the filter circuitrRepresenting a resonant frequency of the filter circuit;
the circuit elements take the values:
C5＝C，
R4＝R5＝2R6，
R8＝R，
R9＝(1-K)R；
wherein C, R is used for setting a reference value,
according to the specific embodiment provided by the invention, the invention discloses the following technical effects: the ultrasonic partial discharge sensor designed by the high-precision signal frequency reduction circuit provided by the invention has a high-precision special frequency reduction circuit, can greatly improve the measurement precision of the sensor, and is mainly divided into a signal detection circuit and a filter circuit; the ultrasonic partial discharge sensor originally uses a multi-stage series-parallel detection circuit, combines advantages and disadvantages of series detection and parallel detection, can isolate direct current components in the detection process, has smaller noise compared with the traditional detection circuit, can not generate inertia distortion and negative peak cutting distortion in the actual measurement process, is more suitable for the detection of small signals than the traditional circuit because the circuit reacts sensitively to small signals, has large dynamic range, has good detection effect for large signals and small signals, and solves the defect that the traditional filter circuit can not give consideration to large and small signals; in addition, the invention provides a special filter circuit, which uses an analog independent active elliptic function band-pass filter to replace a traditional low-order passive filter, and the change of the load has weak influence on the performance of the filter, so that a larger load and a smaller load can be mounted behind the filter, and meanwhile, the filter can effectively adjust the input and output impedance of the circuit, and the network resonance point is more stable and is not easy to shift, thereby reducing the waveform distortion and the voltage loss of signals on a frequency reduction circuit.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a diagram of a detector circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a filter circuit according to an embodiment of the present invention;
fig. 3 is an amplitude-frequency response curve of a filter circuit according to an embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide an ultrasonic partial discharge sensor designed by a high-precision signal frequency reduction circuit, which is provided with a high-precision special signal frequency reduction circuit, has a simple circuit structure, gives consideration to small-signal and large-signal processing and can greatly improve the detection precision and the detection sensitivity of partial discharge.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1-2, the ultrasonic partial discharge sensor designed by the high-precision signal frequency-reducing circuit provided by the present invention includes a high-precision signal frequency-reducing circuit, the high-precision signal frequency-reducing circuit includes a detection circuit and a filter circuit, the detection circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a first diode D1, a second diode D2, a first capacitor C1, and a second capacitor C2, one end of the first resistor R1 is connected to a signal input terminal, the other end of the first resistor R1 is connected to ground, one end of the first diode D1 is connected to a detection signal input terminal, the other end of the first resistor R2 is connected to ground, the other end of the second resistor R2 is connected to ground, the first capacitor C1 is connected to the second resistor R2 in parallel, one end of the second capacitor C2 is connected to a non-ground terminal of the first capacitor C1, the other end of the second capacitor C2 is connected to one end of the second diode D2, the other end of the second diode D2 is grounded, the third resistor R3 is connected in parallel with the second diode D2, and the non-grounded end of the third resistor R3 is connected to the detection signal output end; the detection signal output end is connected with the filtering signal input end; in order to improve the stability and reliability of signals acquired by the front end and further reduce the frequency of original signals, the detection circuit is a specially designed multistage series-parallel connection type detection circuit, and the realization of the detection circuit is favorable for the acquisition of the front end signals by an ADC circuit and the judgment of the discharge times and the discharge phase, so that the pressure of a CPU can be reduced; the signal is input from A, when the voltage at A is higher than that at B, the D1 diode is conducted to charge C1. When the voltage at A is lower than that at B, the diode C1 is turned off, the capacitor C1 discharges through the resistor R1, and the primary detection is finished. The parallel detection process is similar to the series detection process. When diode D2 conducts, the signal charges capacitor C2. When the diode D2 is turned off, the capacitor C2 discharges through R3, thereby completing a detection process. Because the parallel circuit has a lower voltage transmission coefficient than the series circuit, the C2 can also have the function of a DC blocking capacitor, thereby effectively reducing the pressure of a subsequent acquisition system; the signal is input from A, when the voltage at A is higher than that at B, the D1 diode is conducted to charge C1, when the voltage at A is lower than that at B, the diode C1 is turned off, the capacitor C1 is discharged through the resistor R1, the primary detection is finished, and the parallel detection process is similar to the series detection process. When the diode D2 is conducted, a signal charges the capacitor C2, when the diode D2 is cut off, the capacitor C2 discharges through the R3, and therefore a detection process is completed.
As shown in fig. 2, the filter circuit includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, and an operational amplifier a, where the fourth resistor R4 and the fifth resistor R5 are connected in series to form a first branch, one end of the first branch is connected to the filtered signal input terminal, the third capacitor C3 and the fourth capacitor C4 are connected in series to form a second branch, and the second branch is connected in parallel to the first branch and then connected to the positive input terminal of the operational amplifier a; one end of the sixth resistor R6 is connected to the front of the third capacitor C3 and the fourth capacitor C4, and the other end is grounded; one end of the fifth capacitor C5 is connected between the fourth resistor R4 and the fifth resistor R5, the other end is connected to the output end of the operational amplifier a, one end of the fourth resistor R7 is connected to the positive input end of the operational amplifier a, the other end is grounded, one end of the sixth capacitor C6 is connected to the positive input end of the operational amplifier a, and the other end is grounded; one end of the eighth resistor R8 is connected to the inverting input end of the operational amplifier A, and the other end is grounded; one end of the ninth resistor R9 is connected to the inverting input terminal of the operational amplifier a, and the other end is connected to the output terminal of the operational amplifier a. The filter circuit adopts a VCVS network, and the transmission zero point of the VCVS network can be obtained near the pole according to the requirement.
The circuit elements of the filter circuit have the following value relations:
let the median values a, b, c be as follows:
wherein Q represents the quality factor of the circuit, f0Representing the aggregate center frequency, f, of the filter circuitrRepresenting a resonant frequency of the filter circuit;
the circuit elements take the values:
C5＝C，
R4＝R5＝2R6，
R8＝R，
R9＝(1-K)R；
c, R is a reference value, which can be set according to the circuit performance requirement,
fig. 3 is an amplitude-frequency response curve of the filter circuit according to the embodiment of the present invention, as shown in fig. 3, the filter circuit has a narrow transition band, a steep edge, and a passband and a stopband both having equal ripples, and has an excellent edge characteristic, so that the filter circuit not only can filter external interference except for a passband, but also can effectively improve input and output impedance of the whole circuit, and improve accuracy of the detector circuit to a greater extent.
The ultrasonic partial discharge sensor designed by the high-precision signal frequency reduction circuit provided by the invention has a high-precision special frequency reduction circuit, can greatly improve the measurement precision of the sensor, and is mainly divided into a signal detection circuit and a filter circuit; the ultrasonic partial discharge sensor originally uses a multi-stage series-parallel detection circuit, combines advantages and disadvantages of series detection and parallel detection, can isolate direct current components in the detection process, has smaller noise compared with the traditional detection circuit, can not generate inertia distortion and negative peak cutting distortion in the actual measurement process, is more suitable for the detection of small signals than the traditional circuit because the circuit reacts sensitively to small signals, has large dynamic range, has good detection effect for large signals and small signals, and solves the defect that the traditional filter circuit can not give consideration to large and small signals; in addition, the invention provides a special filter circuit, which uses an analog independent active elliptic function band-pass filter to replace a traditional low-order passive filter, and the change of the load has weak influence on the performance of the filter, so that a larger load and a smaller load can be mounted behind the filter, and meanwhile, the filter can effectively adjust the input and output impedance of the circuit, and the network resonance point is more stable and is not easy to shift, thereby reducing the waveform distortion and the voltage loss of signals on a frequency reduction circuit.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (2)
1. An ultrasonic partial discharge sensor designed by a high-precision signal frequency reducing circuit is characterized by comprising the high-precision signal frequency reducing circuit, wherein the high-precision signal frequency reducing circuit comprises a detection circuit and a filter circuit which are electrically connected, the detection circuit comprises a first resistor R1, a second resistor R2, a third resistor R3, a first diode D1, a second diode D2, a first capacitor C1 and a second capacitor C2, one end of the first resistor R1 is connected with a detection signal input end, the other end of the first resistor R1 is grounded, one end of the first diode D1 is connected with the detection signal input end, the other end of the first diode D1 is connected with one end of the second resistor R2, the other end of the second resistor R2 is grounded, the first capacitor C1 is connected with the second resistor R2 in parallel, one end of the second capacitor C2 is connected with a non-grounded end of the first capacitor C1, the other end of the second capacitor C2 is connected with one end of the second diode D2, the other end of the second diode D2 is grounded, the third resistor R3 is connected in parallel with the second diode D2, and the non-grounded end of the third resistor R3 is connected to the detection signal output end; the detection signal output end is connected with the filtering signal input end;
the filter circuit comprises a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6 and an operational amplifier A, wherein the fourth resistor R4 and the fifth resistor R5 are connected in series to form a first branch, one end of the first branch is connected with the filter signal input end, the third capacitor C3 and the fourth capacitor C4 are connected in series to form a second branch, and the second branch is connected with the first branch in parallel and then is connected with the positive input end of the operational amplifier A; one end of the sixth resistor R6 is connected between the third capacitor C3 and the fourth capacitor C4, and the other end is grounded; one end of the fifth capacitor C5 is connected between the fourth resistor R4 and the fifth resistor R5, the other end is connected to the output end of the operational amplifier a, one end of the seventh resistor R7 is connected to the positive input end of the operational amplifier a, the other end is grounded, one end of the sixth capacitor C6 is connected to the positive input end of the operational amplifier a, and the other end is grounded; one end of the eighth resistor R8 is connected to the inverting input end of the operational amplifier A, and the other end is grounded; one end of the ninth resistor R9 is connected to the inverting input terminal of the operational amplifier a, and the other end is connected to the output terminal of the operational amplifier a.
2. The ultrasonic partial discharge sensor designed by the high-precision signal frequency reduction circuit according to claim 1, wherein circuit elements of the filter circuit have the following value relationship:
let the median values a, b, c be as follows:
wherein Q represents the quality factor of the circuit, f0Representing the aggregate center frequency, f, of the filter circuitrRepresenting a resonant frequency of the filter circuit;
the circuit elements take the values:
C5＝C，
R4＝R5＝2R6，
R8＝R，
R9＝(1-K)R；
wherein C, R is used for setting a reference value,
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| CN112838843B (en) * | 2020-12-30 | 2024-02-27 | 北京千方科技股份有限公司 | Signal conditioning device and signal conditioning method |
| CN114189230A (en) * | 2021-10-25 | 2022-03-15 | 中国电子科技集团公司第二十九研究所 | Tunable anti-interference pulse self-checking detection circuit |
| CN114252146B (en) * | 2021-12-10 | 2023-10-24 | 中国计量科学研究院 | Sensitivity frequency characteristic adjustment circuit, vibration sensor, and sensor |
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