CN113884847A - Large-dynamic-range partial discharge ultrahigh frequency signal detection circuit - Google Patents
Large-dynamic-range partial discharge ultrahigh frequency signal detection circuit Download PDFInfo
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- 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
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Abstract
The invention relates to a large dynamic range partial discharge ultrahigh frequency signal detection circuit, which is technically characterized in that: the system comprises a radio frequency power divider, two signal conditioning circuits and a single chip microcomputer module, wherein the input end of the radio frequency power divider is connected with an ultrahigh frequency sensor, the output end of the radio frequency power divider is connected with the input ends of the two signal conditioning circuits, and the output ends of the two signal conditioning circuits are connected with the single chip microcomputer module; the first signal conditioning circuit is formed by sequentially connecting a radio frequency amplification module, a radio frequency detection module, a signal second-stage amplification module and a signal third-stage amplification module, and the second signal conditioning circuit is formed by sequentially connecting a radio frequency detection module, a signal second-stage amplification module and a signal third-stage amplification module. The invention greatly improves the dynamic range of the partial discharge ultrahigh frequency signal detection, can more accurately obtain the severity of the partial discharge of the high-voltage electrical equipment, and can be widely used for detecting the partial discharge ultrahigh frequency signal with a large dynamic range.
Description
Technical Field
The invention belongs to the technical field of high-voltage electrical equipment, relates to insulation state detection of the high-voltage electrical equipment, and particularly relates to a large-dynamic-range partial discharge ultrahigh-frequency signal detection circuit.
Background
The partial discharge phenomenon is both a sign of insulation cracking of electrical equipment and a reason for further insulation cracking. When partial discharge occurs, an ultrahigh frequency electromagnetic wave signal is generated, and the intensity of the generated electromagnetic wave signal is influenced by various factors such as the level of applied voltage, the degree of defect, an insulating material and the like, so that the dynamic range of the intensity of the generated electromagnetic wave signal is large. In actual engineering, most partial discharge occurs inside equipment, and in the process that electromagnetic wave signals are transmitted from the inside of the equipment to the outside of the equipment, the attenuation is severe, and the signals are abnormal and weak; when partial discharge occurs outside the equipment and the discharge intensity is high, the amplitude of the radiated ultrahigh frequency electromagnetic wave signal is high. The dynamic range of the partial discharge uhf signal is typically over 70 dB.
At present, the signal detection principle of the existing partial discharge detection device based on the ultrahigh frequency method is shown in fig. 4, and the partial discharge detection device is formed by sequentially connecting an ultrahigh frequency sensor, a signal amplification module, a signal detection module and a signal acquisition module. The signal detected by the ultrahigh frequency sensor reaches a certain amplitude after being amplified by the signal amplification module, and then the signal detection module carries out signal detection to reduce the signal frequency so as to reduce the requirement of the signal acquisition module on the parameter of the sampling rate, thereby reducing the cost of the whole detection equipment. However, it is difficult to achieve distortion-free amplification of more than 70dB by using a single signal amplification module, and the signal detection module has the same problems: for signals with a dynamic range greater than 70dB, it is difficult to achieve effective linear amplification, which results in distortion problems for the detected uhf signals.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a partial discharge ultrahigh frequency signal detection circuit with a large dynamic range, which can greatly improve the dynamic range of partial discharge ultrahigh frequency signal detection.
The invention solves the technical problems in the prior art by adopting the following technical scheme:
a large dynamic range partial discharge ultrahigh frequency signal detection circuit comprises a radio frequency power divider, two signal conditioning circuits and a single chip microcomputer module, wherein the input end of the radio frequency power divider is connected with an ultrahigh frequency sensor, the output end of the radio frequency power divider is connected with the input ends of the two signal conditioning circuits, the output ends of the two signal conditioning circuits are connected with the single chip microcomputer module, and the single chip microcomputer module analyzes and processes conditioned signals and outputs detection results; the first signal conditioning circuit is formed by sequentially connecting a radio frequency amplification module, a first radio frequency detection module, a signal secondary amplification module, a first secondary detection module and a first signal three-stage amplification module, and the second signal conditioning circuit is formed by sequentially connecting a second radio frequency detection module, a second secondary detection module and a second signal three-stage amplification module.
Moreover, the bandwidth range of the radio frequency power divider is as follows: 300MHz-1.5GHz, the radio frequency power divider divides the signal detected by the ultrahigh frequency sensor into two paths and outputs the two paths to the two signal conditioning circuits respectively.
Moreover, the bandwidth range of the radio frequency amplification module is as follows: 300MHz-1.5GHz, gain is not lower than 20dB, the radio frequency amplification module adopts ADL5545 radio frequency amplification module to realize.
And the first radio frequency detection module and the second radio frequency detection module both adopt an LTC5508 type radio frequency signal detector to build a signal detection module for extracting the envelope of the ultrahigh frequency signal.
And the signal secondary amplification module is realized by adopting an in-phase proportional amplification circuit and is used for further amplifying the envelope signal output by the previous stage.
And the first secondary detection module and the second secondary detection module are both realized by adopting resistance-capacitance detectors and are used for further broadening the amplified envelope signal.
And the first signal three-stage amplification module and the second signal three-stage amplification module are both realized by adopting in-phase proportional amplification circuits, the difference of the two signal three-stage amplification modules is that the amplification factors of the two signal amplification modules are different, the two signal three-stage amplification modules are used for amplifying the signal output by the secondary detection module again so as to facilitate the acquisition of the single chip microcomputer module, the power supply of the signal three-stage amplification module adopts +/-5V for power supply, and the maximum output voltage of the signal three-stage amplification module is 5V.
And the single chip microcomputer module adopts an STM32 single chip microcomputer, acquires signals output by the signal three-stage amplification module by using the analog-to-digital conversion module, and performs digital signal processing inside the single chip microcomputer to acquire accurate pulse amplitude of the partial discharge source.
Moreover, the processing method of the single chip microcomputer module comprises the following steps: performing analog-to-digital conversion and storage on signals output by the two signal three-stage amplification modules; extracting the amplitude and the position of a pulse signal in the first path of signal array; extracting the amplitude and the position of the pulse signal in the second signal array according to the analysis result of the first signal and analyzing the pulse signal; and outputting the detection result.
And the sampling rate of the single chip microcomputer module is 200 kS/s.
The invention has the advantages and positive effects that:
the invention has reasonable design, and the two signal conditioning circuits are adopted to condition the signals detected by the ultrahigh frequency sensor and input the conditioned signals into the single chip microcomputer module for analysis and processing, thereby greatly improving the dynamic range of the detection of the partial discharge ultrahigh frequency signals, more accurately obtaining the partial discharge severity of the high-voltage electrical equipment and more accurately sensing the running state of the electrical equipment; meanwhile, the circuit has lower requirements on equipment parameters, can effectively reduce the equipment cost, and can be widely used for detecting partial discharge ultrahigh frequency signals in a large dynamic range.
Drawings
FIG. 1 is a block diagram of a high dynamic range partial discharge UHF signal detection circuit in accordance with the present invention;
FIG. 2a is a circuit diagram of a first signal conditioning circuit of the present invention;
FIG. 2b is a circuit diagram of a second signal conditioning circuit of the present invention;
FIG. 3 is a flow chart of the internal signal processing of the single-chip module of the present invention;
fig. 4 is a schematic block diagram of a conventional partial discharge uhf signal conditioning circuit.
Detailed Description
The embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The invention provides a high-dynamic-range partial discharge ultrahigh-frequency signal detection circuit, which comprises a radio-frequency power divider, two signal conditioning circuits and a single chip microcomputer module, wherein the input end of the radio-frequency power divider is connected with an ultrahigh-frequency sensor, the output end of the radio-frequency power divider is connected with the input ends of the two signal conditioning circuits, and the output ends of the two signal conditioning circuits are connected with the single chip microcomputer module, as shown in fig. 1, fig. 2a and fig. 2 b. The first signal conditioning circuit is formed by sequentially connecting a radio frequency amplification module, a radio frequency detection module 1, a signal secondary amplification module, a secondary detection module 1 and a signal tertiary amplification module 1, and the second signal conditioning circuit is formed by sequentially connecting a radio frequency detection module 2, a secondary detection module 2 and a signal tertiary amplification module 2.
The bandwidth range of the radio frequency power divider covers the range of 300MHz-1.5GHz, the radio frequency power divider is provided with 1 input port and 2 output ports, and the radio frequency power divider has the function of dividing signals detected by the ultrahigh frequency sensor into two paths and respectively conditioning the two paths by two conditioning branches.
The bandwidth range of the radio frequency amplification module covers the range of 300MHz-1.5GHz, the gain is not lower than 20dB, the radio frequency amplification module is realized by using an ADL5545 radio frequency amplification module, and the function of the radio frequency amplification module is to amplify weak ultrahigh frequency signals so as to meet the requirement of the input amplitude of a subsequent signal detection module.
The two radio frequency detection modules (the radio frequency detection module 1 and the radio frequency detection module 2) both adopt an LTC5508 type radio frequency signal detector to build a signal detection module, and the signal detection module has the function of extracting the envelope of an ultrahigh frequency signal.
The signal secondary amplification module is realized by adopting an in-phase proportional amplification circuit, and has the function of further amplifying the envelope signal output by the previous stage.
The two secondary detection modules (the secondary detection module 1 and the secondary detection module 2) are realized by adopting a resistance-capacitance detector, and the function of the detector is to further widen the amplified envelope signal so that the detector can be matched with a lower-speed acquisition circuit.
The two signal three-stage amplification modules (the signal three-stage amplification module 1 and the signal three-stage amplification module 2) are both realized by adopting in-phase proportional amplification circuits, the difference is that the amplification factors of the two signal amplification modules are different, the function of the three-stage amplification modules is to amplify the signal output by secondary detection again so as to realize the acquisition of a digital-to-analog conversion module of the single chip microcomputer module, the power supply of the three-stage amplification modules adopts +/-5V for power supply, and the maximum output voltage of the three-stage amplification modules is 5V.
The single chip microcomputer module adopts an STM32 single chip microcomputer as a core, an analog-to-digital conversion module of the single chip microcomputer module is used for collecting signals output by three-stage amplification, digital signal processing is carried out in the single chip microcomputer, and accurate pulse amplitude of the local discharge source is obtained.
The working principle of the signal conditioning circuit is as follows: after the ultrahigh frequency sensor detects a partial discharge signal, the signal is divided into two paths by the radio frequency power divider and output to the first signal conditioning circuit and the second signal conditioning circuit, wherein one path is marked as CH1(t), and the other path is marked as CH2 (t). The signal CH1(t) is amplified by the rf amplification module with an amplification factor of 20dB, and then the envelope of the signal CH1(t) is obtained by the signal detection module and recorded as CH1_ env (t). The envelope signal CH1_ env (t) is amplified by the signal secondary amplification module 1, and the amplification factor is set to 10 dB. And then secondary detection is carried out, and the envelope signal is further widened until the pulse width reaches 200us, which is recorded as CH1_ env _200 (t). And the signal three-stage amplification module amplifies CH1_ env _200(t) by 20dB again, and then the amplified signal is output to an analog-to-digital conversion interface of the singlechip module. The signal CH2(t) is subjected to envelope detection by a radio frequency detection module to obtain an envelope CH2_ env (t) of CH2(t), and the envelope CH2_ env (t) is further widened by a secondary detection module until the pulse width reaches 200us, which is recorded as CH2_ env _200 (t). And the CH2_ env _200(t) is amplified again by the signal three-stage amplification module and then output to an analog-to-digital conversion interface of the singlechip module.
According to the output of the secondary detection module, the pulse width of partial discharge reaches 200us, and the sampling rate is set to be 200 kS/s.
The single chip module processes the signals output by the two signal conditioning circuits, as shown in fig. 3, the specific processing process is as follows:
s1: and D/A conversion and storage of the signals.
The analog-to-digital conversion acquisition of the singlechip module converts output signals of the two signal conditioning circuits into digital signals CH1[ N ] and CH2[ N ], wherein N is 1, 2, 3, N, and N is the number of sampling points, and four null arrays are established in the RAM and are marked as CH1_ A [ N ], CH1_ B [ N ], CH2_ A [ N ] and CH2_ B [ N ]. The two signals are read by DMA and stored in RAM inside the arrays CH1_ A [ n ] and CH2_ A [ n ], respectively. When the main program detects that the arrays CH1_ A [ n ] and CH2_ A [ n ] are not empty, step S2 is initiated, and two newly converted signals are stored in the arrays CH1_ B [ n ] and CH2_ B [ n ].
S2: the amplitude and position of the pulse signal in the array of CH1_ A [ n ] are extracted.
S201: establishing two null groups for storing the amplitude and the position of a partial discharge pulse signal in CH1_ A [ n ], wherein the two null groups are marked as val [ ] and pos [ ];
s202: from array CH1_ A [ n ]]The sampling positions of the 50 sampling points are from the (m + 50+1) th sampling point to the ((m +1) × 50+1) th sampling point, m is the number of times of executing the step S202, and m is counted from 0 and is marked as Sm[n]Statistics of sm[t]And extracting the maximum value in the array CH1_ A [ n [ ]]Position p inVmax；
S203: store V _ Amax in array val [ i ]]In the above, i is counted from 1, represents the number of the discovery pulse signals, and p isVmaxStored in the array pos [ i ]]Performing the following steps;
s204: let m be m +1, go to step S3 when m > N/50, otherwise repeat step S202.
S3: the amplitude and position of the pulse signal in the array of CH2_ A [ n ] are extracted.
S301: the signal amplitude V _ Bmax in the array CH2_ A [ n ] is sequentially extracted according to the position in the array corresponding to the pulse peak value stored in the array pos [ ].
S302: if V _ Amax <5V and V _ Bmax > is 4.95V, the element at the corresponding position in the array val [ ] is replaced by V _ Amax divided by 10. If V _ Amax <5V, and V _ Bmax <5V, then V _ Bmax is substituted for the corresponding element in the array val [ ].
S4: all elements of the array val [ ] are calculated according to the formula (1), the signal unit is converted from "V" to "dBmV", and then the stored results in the arrays val [ ] and pos [ ] are output.
val[i]＝20log(val[i]*1000) (1)
After the processing of S1-S4 is completed, the main program of the single chip microcomputer module continues to detect whether the array CH1_ B [ ] is full, when the array CH1_ B [ ] is full, the steps S1-S4 are repeatedly executed, and the array CH1_ A [ ] in the 4 steps is replaced by the array CH1_ B [ ].
It should be emphasized that the embodiments described herein are illustrative rather than restrictive, and thus the present invention is not limited to the embodiments described in the detailed description, but also includes other embodiments that can be derived from the technical solutions of the present invention by those skilled in the art.
Claims (10)
1. A large dynamic range partial discharge ultrahigh frequency signal detection circuit is characterized in that: the system comprises a radio frequency power divider, two signal conditioning circuits and a single chip microcomputer module, wherein the input end of the radio frequency power divider is connected with an ultrahigh frequency sensor, the output end of the radio frequency power divider is connected with the input ends of the two signal conditioning circuits, the output ends of the two signal conditioning circuits are connected with the single chip microcomputer module, and the single chip microcomputer module analyzes and processes conditioned signals and outputs detection results; the first signal conditioning circuit is formed by sequentially connecting a radio frequency amplification module, a first radio frequency detection module, a signal secondary amplification module, a first secondary detection module and a first signal three-stage amplification module, and the second signal conditioning circuit is formed by sequentially connecting a second radio frequency detection module, a second secondary detection module and a second signal three-stage amplification module.
2. The large dynamic range partial discharge uhf signal detection circuit of claim 1, wherein: the bandwidth range of the radio frequency power divider is as follows: 300MHz-1.5GHz, the radio frequency power divider divides the signal detected by the ultrahigh frequency sensor into two paths and outputs the two paths to the two signal conditioning circuits respectively.
3. The large dynamic range partial discharge uhf signal detection circuit of claim 1, wherein: the bandwidth range of the radio frequency amplification module is as follows: 300MHz-1.5GHz, gain is not lower than 20dB, the radio frequency amplification module adopts ADL5545 radio frequency amplification module to realize.
4. The large dynamic range partial discharge uhf signal detection circuit of claim 1, wherein: the first radio frequency detection module and the second radio frequency detection module both adopt an LTC5508 type radio frequency signal detector to build a signal detection module for extracting the envelope of the ultrahigh frequency signal.
5. The large dynamic range partial discharge uhf signal detection circuit of claim 1, wherein: the signal secondary amplification module is realized by adopting an in-phase proportional amplification circuit and is used for further amplifying the envelope signal output by the previous stage.
6. The large dynamic range partial discharge uhf signal detection circuit of claim 1, wherein: and the first secondary detection module and the second secondary detection module are both realized by adopting resistance-capacitance detectors and are used for further broadening the amplified envelope signals.
7. The large dynamic range partial discharge uhf signal detection circuit of claim 1, wherein: the first signal three-stage amplification module and the second signal three-stage amplification module are both realized by adopting an in-phase proportional amplification circuit, the two signal three-stage amplification modules are different in amplification factor and used for amplifying the signal output by the secondary detection module again so as to facilitate the acquisition of the single chip microcomputer module, a power supply of the signal three-stage amplification module adopts +/-5V for power supply, and the maximum output voltage of the signal three-stage amplification module is 5V.
8. The large dynamic range partial discharge uhf signal detection circuit of claim 1, wherein: the single chip microcomputer module adopts an STM32 single chip microcomputer, and utilizes an analog-to-digital conversion module to acquire signals output by the signal three-stage amplification module, and digital signal processing is carried out in the single chip microcomputer to acquire accurate pulse amplitude of the local discharge source.
9. The large dynamic range partial discharge uhf signal detection circuit of claim 1, wherein: the processing method of the single chip microcomputer module comprises the following steps: performing analog-to-digital conversion and storage on signals output by the two signal three-stage amplification modules; extracting the amplitude and the position of a pulse signal in the first path of signal array; extracting the amplitude and the position of the pulse signal in the second signal array according to the analysis result of the first signal and analyzing the pulse signal; and outputting the detection result.
10. The large dynamic range partial discharge uhf signal detection circuit of claim 1, wherein: the sampling rate of the single chip microcomputer module is 200 kS/s.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114384383A (en) * | 2022-03-22 | 2022-04-22 | 东华理工大学南昌校区 | Circuit and method for positioning ultrahigh frequency partial discharge point |
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| CN114384383A (en) * | 2022-03-22 | 2022-04-22 | 东华理工大学南昌校区 | Circuit and method for positioning ultrahigh frequency partial discharge point |
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