Partial discharge peak measurement method and measurement circuit based on single chip microcomputer

Abstract

The present invention discloses a method and circuit for measuring the peak value of partial discharge based on a single chip microcomputer, which belongs to the field of partial discharge detection and diagnosis of power equipment. The method uses a first operational amplifier unit to collect the partial discharge signal, and its inverting input terminal receives the output signal of the second operational amplifier unit. The voltage V1 of the output signal of the first operational amplifier unit is compared with the noise voltage V ref , if V1 is greater than V ref , then the first operational amplifier unit and the energy storage capacitor are turned on, and the voltage V1 and the voltage V2 of the output signal of the second operational amplifier unit are further compared. If V1 is greater than V2, the energy storage capacitor is charged, otherwise the energy storage capacitor maintains the voltage V2. When V2 is greater than the reference voltage V DAC When increasing V DAC Otherwise, the monostable multivibrator unit generates an excitation pulse, which controls the second analog switch to discharge the energy storage capacitor and output V DAC The present invention realizes accurate peak value capture of partial discharge signal through progressive comparison and is applicable to monitoring of high voltage equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of discharge detection of electric power equipment, and in particular to a partial discharge peak value measurement method and a measurement circuit based on a single chip microcomputer. Background Art

[0002] Partial discharge (PD) is the main manifestation of electrical insulation failure in power equipment. The detection and diagnosis of insulation defects requires the collection of partial discharge signals. Signal peak detection is widely used in the fields of wireless communication and radio frequency systems. Digital wireless communication signals have a relatively stable detection envelope, so the amplitude / peak measurement of wireless communication signals can usually be achieved using a detector. However, the ultra-high frequency (UHF) partial discharge signal is composed of a high-speed pulse train with a certain repeatability but a non-fixed period, and the duty cycle is low. The bandwidth of the ultra-high frequency partial discharge signal can reach more than 1GHz. Usually, after filtering and amplification, it is frequency-reduced using the envelope detection method. The partial discharge signal after detection and frequency reduction is still a pulse signal, and its bandwidth is generally between several MHz and several 10 MHz. For example Figure 1 The ultra-high frequency partial discharge signal of the main circuit is filtered, amplified, and detected to obtain a detectable partial discharge signal. The partial discharge detection system of high-voltage equipment generally uses analog-to-digital conversion (ADC) to digitize the detected partial discharge signal, and then performs various digital signal processing according to the application requirements. For applications that require peak detection, parameters such as the peak value of the partial discharge signal can be extracted through the digital processing unit. Due to the low duty cycle characteristics of the partial discharge signal, when continuous sampling is performed using the ADC, most of the data is invalid data corresponding to zero values or noise interference, while valid data only exists in the short partial discharge pulse part. In addition, the high power consumption and high cost of high-speed ADCs further increase the challenges of realizing partial discharge positioning and classification in resource-constrained power Internet of Things sensor terminals. Therefore, it is necessary to design a low-data-volume, low-power partial discharge signal peak detection technology that is suitable for implementing insulation defect diagnosis of power equipment on resource-constrained hardware platforms. Summary of the Invention

[0003] Aiming at the high-speed, ultra-wideband, low duty cycle and non-stationary characteristics of ultra-high frequency partial discharge signals in high-voltage equipment, the present invention provides a partial discharge peak measurement method and measurement circuit based on a single-chip microcomputer. The single-chip microcomputer is used to directly detect the discharge peak, avoiding the storage, processing and transmission of large-scale continuous sampling partial discharge data.

[0004] The invention objectives of this application can be achieved through the following technical means:

[0005] A method for measuring a partial discharge peak value based on a single chip microcomputer comprises the following steps:

[0006] Step 1: The non-inverting input terminal of the first operational amplifier unit collects the partial discharge signal, the first operational amplifier unit responds to the partial discharge signal and generates an output signal, and the inverting input terminal of the first operational amplifier unit receives the output signal of the second operational amplifier unit;

[0007] Step 2: Compare the voltage V1 of the output signal of the first op amp unit with the noise voltage V ref , if V1 is greater than V ref , the first analog switch connects the first operational amplifier unit and the energy storage capacitor, and the process proceeds to step 3; otherwise, the first operational amplifier unit and the energy storage capacitor are disconnected, and the process returns to step 1;

[0008] Step 3: Compare the voltage V1 of the output signal of the first operational amplifier unit with the voltage V2 of the output signal of the second operational amplifier unit. When V1 is greater than V2, proceed to step 4. When V1 is less than V2, proceed to step 7. Otherwise, the inverting input terminal of the first operational amplifier unit and the output terminal of the second operational amplifier unit are in a virtual disconnect state, and return to step 1.

[0009] Step 4: The first diode is reverse-blocked, the second diode is forward-biased, the energy storage capacitor is in a charging state, and the voltage V2 increases;

[0010] Step 5: Compare V2 with the reference voltage V DAC , if V2 is greater than or equal to V DAC , V DAC Increment, store the incremented V DAC , return to step 1, otherwise go to step 6;

[0011] Step 6: The monostable multivibrator unit generates an excitation pulse. When the second analog switch receives the excitation pulse, it connects both ends of the energy storage capacitor to the ground. The energy storage capacitor is in a discharge state and outputs V DAC And calculate the peak voltage of the partial discharge signal, and return to step 1;

[0012] Step 7: The first diode is forward-biased, the second diode is reverse-biased, the voltage V2 remains unchanged, and the process returns to step 1.

[0013] A measurement circuit for implementing the single chip microcomputer-based partial discharge peak measurement method, comprising:

[0014] A first operational amplifier unit, wherein a non-inverting input terminal of the first operational amplifier unit is connected to a main circuit for collecting partial discharge signals;

[0015] Energy storage capacitor, used to receive partial discharge signals and charge;

[0016] a first diode, used for connecting in series the inverting input terminal and the output terminal of the first operational amplifier unit;

[0017] a second diode, the second diode being located between the output end of the first operational amplifier unit and the energy storage capacitor;

[0018] a second operational amplifier unit, wherein a non-inverting input terminal of the second operational amplifier unit is connected to an output terminal of the first operational amplifier unit through a second diode;

[0019] The single chip microcomputer includes a denoising unit and a peak measurement unit. The denoising unit is used to compare the voltage V1 of the output signal of the first operational amplifier unit with the noise voltage V ref The peak measurement unit is used to compare the voltage V2 of the output signal of the second operational amplifier unit with the reference voltage V DAC ;

[0020] The first analog switch is used when V1 is greater than V ref When the output terminal of the first operational amplifier unit and the energy storage capacitor are turned on;

[0021] Monostable multivibrator unit, used when V2 is less than V DAC Output an excitation pulse when

[0022] The second analog switch is used to ground both ends of the energy storage capacitor when receiving an excitation pulse, wherein:

[0023] When V1 is greater than V2, the first diode is reverse-cut off, the second diode is forward-biased, the energy storage capacitor is in a charging state, and the voltage V2 increases.

[0024] When V1 is equal to V2, the inverting input terminal of the first operational amplifier unit and the output terminal of the second operational amplifier unit are in a virtual disconnect state.

[0025] When V1 is less than V2, the first diode is forward-biased, the second diode is reverse-biased, and the voltage V2 remains unchanged.

[0026] In the present invention, V2 is greater than or equal to V DAC When the peak measurement unit increases by V DAC , and store the incremented V DAC , V2 is less than V DAC When the peak measurement unit outputs V DAC Then V DAC Reset to initial voltage V th .

[0027] In the present invention, the inverting input terminal of the first operational amplifier unit is connected to the output terminal of the second operational amplifier unit via a current limiting resistor, and the inverting input terminal of the second operational amplifier unit is connected to the output terminal of the second operational amplifier unit.

[0028] In the present invention, the denoising unit includes a first comparator and a first converter, the first converter outputs a noise voltage to the first comparator, the peak measurement unit includes a second comparator and a second converter, the second converter outputs a reference voltage to the second comparator, and when the second comparator is at a high level, the second converter increases the reference voltage.

[0029] In the present invention, the first diode and the second diode are Schottky diodes.

[0030] In the present invention, a calculation unit is also included, which is used to calculate the value of the V DAC Calculate the peak voltage of the partial discharge signal.

[0031] In the present invention, the measurement circuit further includes a radio frequency bandpass filter, a low noise amplifier, and a detector, which are located between the main loop and the non-inverting input terminal of the first operational amplifier unit.

[0032] In the present invention, the monostable multivibrator unit has an adjusting resistor and an adjusting capacitor, and the duration of the excitation pulse is controlled according to the adjusting resistor and the adjusting capacitor.

[0033] The partial discharge peak value measurement method and measurement circuit based on a single chip microcomputer of the present invention have the following beneficial effects:

[0034] 1. The present invention uses a peak measurement unit (DAC module) in a single-chip microcomputer to maintain and record the discharge peak value, which simplifies the circuit structure, makes the measurement results more stable and reliable, and is easy to implement, while not affecting other applications of the single-chip microcomputer function.

[0035] 2. The present invention can achieve peak measurement of partial discharge signals without a high-speed ADC converter, reducing power consumption, eliminating the need for large-capacity data storage and processing, lowering system requirements and costs, and is suitable for actual on-site deployment of partial discharge sensor terminals with limited resources.

[0036] 3. The single-chip microcomputer of the present invention directly records the peak voltage, which does not require complex data processing on site to extract the peak voltage of the partial discharge signal, nor does it require a large amount of data transmission for remote data processing to extract the peak voltage, thereby reducing the burden of wireless communication and meeting the application requirements of the power Internet of Things sensor terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The following is a schematic diagram of an existing partial discharge peak measurement circuit;

[0038] Figure 2 The schematic diagram of the measurement circuit for realizing the partial discharge peak value measurement method based on a single chip microcomputer according to the present invention;

[0039] Figure 3 This is a flow chart of a partial discharge peak value measurement method based on a single chip microcomputer according to the present invention;

[0040] Figure 4 This is a discharge waveform diagram of the partial discharge peak value measurement method based on a single chip microcomputer of the present invention;

[0041] Figure 5 A partial schematic diagram of a measurement circuit for implementing the single chip microcomputer-based partial discharge peak measurement method of the present invention;

[0042] Figure 6 Schematic diagram of partial discharge signal in the main circuit of the present invention;

[0043] Figure 7 A schematic diagram of a partial discharge signal input to a first operational amplifier unit according to the present invention;

[0044] Figure 8 Schematic diagram of the output signal of the second operational amplifier unit of the present invention;

[0045] Figure 9 is a schematic diagram of a radio frequency bandpass filter of the present invention;

[0046] Figure 10 is a schematic diagram of a low noise amplifier of the present invention;

[0047] Figure 11 is a schematic diagram of a detector of the present invention;

[0048] Figure 12 It is the working flow chart of the single chip microcomputer of the present invention. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0050] like Figure 1 The traditional partial discharge detection receiver includes a front-end signal preprocessing unit consisting of filtering, amplification and detection, ADC analog-to-digital conversion and data storage and processing units. This method of extracting signal characteristics such as peak values by digitizing the signal has the disadvantages of large data volume, high power consumption and complex data processing. To solve the above problems, the present invention adopts a partial discharge peak measurement method based on a single-chip microcomputer. Figure 2 The measurement circuit of the present invention utilizes a peak hold circuit, and a single-chip microcomputer implements peak measurement of the partial discharge signal. Finally, a computation unit outputs the peak voltage of the partial discharge signal. Furthermore, the present invention also includes a front-end signal processing circuit comprised of filtering, amplification, and detection. This circuit receives the ultra-high frequency partial discharge signal from the main circuit and, through filtering, amplification, and detection, converts it into a processable partial discharge signal for output. Example 1

[0051] Reference Figure 3 The partial discharge peak value measurement method based on a single chip microcomputer of the present invention described in detail in this embodiment includes the following steps.

[0052] Step 1: The non-inverting input terminal of the first operational amplifier unit collects the partial discharge signal, the first operational amplifier unit responds to the partial discharge signal and generates an output signal, and the inverting input terminal of the first operational amplifier unit receives the output signal of the second operational amplifier unit.

[0053] Step 2: Compare the voltage V1 of the output signal of the first op amp unit with the noise voltage V ref , if V1 is greater than V ref , the first analog switch connects the first operational amplifier unit and the energy storage capacitor, and the process goes to step 3; otherwise, the first operational amplifier unit and the energy storage capacitor are disconnected, and the process returns to step 1.

[0054] Step 3: Compare the voltage V1 of the output signal of the first operational amplifier unit with the voltage V2 of the output signal of the second operational amplifier unit. When V1 is greater than V2, proceed to step 4. When V1 is less than V2, proceed to step 7. Otherwise, the inverting input terminal of the first operational amplifier unit and the output terminal of the second operational amplifier unit are in a virtual disconnect state, and return to step 1. Voltage V2 is the voltage across the energy storage capacitor.

[0055] Step 4: The first diode is reverse-blocked, the second diode is forward-biased, the energy storage capacitor is in a charging state, and voltage V2 increases. When V1 is greater than V2, the partial discharge signal is in the rising phase, the voltage at the non-inverting input of the first op amp is greater than the inverting input of the first op amp, and the first op amp outputs voltage V1. The first diode is reverse-blocked, and the second diode is forward-biased. Voltage V1 charges the energy storage capacitor through the second diode, and the energy storage capacitor is connected to the non-inverting input of the second op amp, causing voltage V2 to increase.

[0056] Step 5: Compare V2 with the reference voltage V DAC , if V2 is greater than or equal to V DAC , V DAC Increment, store the incremented V DAC , return to step 1, otherwise go to step 6. The present invention does not limit V DAC Incremental voltage step size: When the peak voltage needs to be detected quickly, a larger voltage step size is set to increase the iteration speed. When the detection accuracy needs to be improved, a smaller voltage step size is set.

[0057] Step 6: The monostable multivibrator unit generates an excitation pulse. When the second analog switch receives the excitation pulse, it connects both ends of the energy storage capacitor to the ground. The energy storage capacitor is in a discharge state and outputs V DAC And calculate the peak voltage of the partial discharge signal and return to step 1. In this embodiment, the peak voltage is 1V. Output V DAC Then reset the reference voltage.

[0058] Step 7: The first diode is forward-biased, the second diode is reverse-biased, and voltage V2 remains unchanged. The process returns to step 1. When V1 is less than V2, the partial discharge signal is in its declining phase, voltage V1 decreases, the second diode is reverse-biased, V2 reaches the peak voltage of the partial discharge signal, and the energy storage capacitor maintains voltage V2 unchanged. Ideally, a diode has two states: forward conduction and reverse cutoff. In specific embodiments, forward conduction can be understood as forward bias, or connecting the positive electrode to the P region (anode) and the negative electrode to the N region (cathode). Reverse bias can be understood as reverse cutoff, or connecting the positive electrode to the N region (cathode) and the negative electrode to the P region (anode). Example 2

[0059] Reference Figures 4 to 8 A measurement circuit for implementing the partial discharge peak measurement method based on a single-chip microcomputer includes a first operational amplifier unit, a storage capacitor, a first diode, a second diode, a second operational amplifier unit, a single-chip microcomputer, a first analog switch, a monostable multivibrator unit and a second analog switch.

[0060] The non-inverting input of the first operational amplifier unit is connected to the main circuit for collecting partial discharge signals. The first operational amplifier is implemented using a high-speed operational amplifier. In this embodiment, the high-speed operational amplifier selected is, for example, a COS8092, which has a 350MHz@-3dB bandwidth and a quiescent operating current of 4.5mA. The first operational amplifier unit is used to output a voltage V1 and charge the energy storage capacitor.

[0061] The energy storage capacitor is used to receive the partial discharge signal and charge. In this embodiment, the capacity of the energy storage capacitor C1 is 4nF.

[0062] The first diode is connected in series with the inverting input and output of the first operational amplifier unit. The second diode is located between the output of the first operational amplifier unit and the energy storage capacitor. The first and second diodes are Schottky diodes, which have low forward voltage drop and extremely short reverse recovery time. For example, the model of the Schottky diode is IN5819.

[0063] The non-inverting input of the second operational amplifier unit is connected to the output of the first operational amplifier unit via a second diode. The inverting input of the first operational amplifier unit is connected to the output of the second operational amplifier unit via a current-limiting resistor, and the inverting input of the second operational amplifier unit is connected to the output of the second operational amplifier unit. In this embodiment, the resistance of the current-limiting resistor R1 is 1 kΩ.

[0064] The single chip microcomputer includes a noise removal unit and a peak measurement unit. The single chip microcomputer is, for example, an STM32L476 single chip microcomputer.

[0065] The denoising unit is used to compare the voltage V1 of the output signal of the first operational amplifier unit with the noise voltage Vref , its physical meaning is to eliminate the interference noise of the partial discharge signal. The denoising unit includes a first comparator and a first converter. The first converter outputs a noise voltage to the first comparator. The model of the first comparator is, for example, TLV3502. Noise voltage V ref It can be given by the first converter according to actual needs. When the system noise and interference in the working environment are strong, the noise voltage V ref Can be increased appropriately, otherwise, the noise voltage V ref Can be reduced appropriately.

[0066] The peak measurement unit is used to compare the voltage V2 of the output signal of the second operational amplifier unit with the reference voltage V DAC The peak measurement unit includes a second comparator and a second converter. The second converter outputs a reference voltage to the second comparator. When the second comparator is at a high level, the second converter increases the reference voltage. V2 is greater than or equal to V DAC When the peak measurement unit changes V DAC Increment and store the incremented V DAC , V2 is less than V DAC When the peak measurement unit outputs V DAC Then V DAC Reset to initial voltage V th The initial voltage is set to a lower value according to actual needs. Since the peak voltages of different partial discharge signals are not stable and consistent, in order to ensure that the peak voltages of various partial discharge signals are monitored, the initial voltage V th It should not be set too high.

[0067] Increment V DAC The voltage step size can be 20mV, and the initial voltage V th It can be 0.2V. Figure 4 The measurement time of the peak voltage is related to the size of the peak voltage and the speed of the second converter. When the speed of the second converter is fixed, the larger the peak voltage, the longer the measurement time. The accuracy of the peak voltage collected by the second converter is affected by the voltage step size and the speed of the second converter. If the voltage step size is large, the collected peak voltage may be much larger than the actual peak voltage, resulting in a large measurement error. If the voltage step size is small, the reference voltage V DAC A larger number of increments is required to achieve peak voltage measurement, and the measurement time is longer.

[0068] In a more preferred embodiment, the initial voltage V th =max(αV min , kV ref ), voltage step ΔV=βV0 / 2 N , where V minis the minimum value of the most recent peak voltage recorded, k is the noise safety factor, k is between 1.5 and 3, α is the peak adjustment factor, 0.1≤α≤0.3, N is the number of bits of resolution of the second converter, V0 is the reference voltage of the second converter (determined by the hardware design of the second converter), the reference voltage determines the maximum reference voltage that the second converter can output, and β is the incremental step size, β∈{1, 2, 3, 4}. In this embodiment, the second converter has a resolution of 8 bits, a reference voltage of 3.3V, and β is 2, so the voltage step size ΔV=2 / 2 8 ×3.3V=25.78mV. Figure 8 , the measurement time is 75us, and the peak voltage collected is 1V.

[0069] The first analog switch is used when V1 is greater than V ref When the first analog switch is closed, the output end of the first operational amplifier unit is connected to the energy storage capacitor, and the energy storage capacitor is in a charging state. When the first analog switch is opened, the measurement circuit is in a peak hold state.

[0070] The monostable multivibrator unit is used when V2 is less than V DAC The monostable multivibrator unit outputs an excitation pulse at a certain time. The monostable multivibrator unit has an adjustable resistor and an adjustable capacitor, and the duration of the excitation pulse is controlled according to the adjustable resistor and the adjustable capacitor. In this embodiment, the monostable multivibrator unit is a model 74LVC1G123, for example, and is used to output an excitation pulse of a fixed duration. The fixed duration can be set according to the adjustable resistor and the adjustable capacitor. The resistance of the adjustable resistor is 10kΩ, and the capacitance of the adjustable capacitor is 10nF.

[0071] The second analog switch is used to ground the two ends of the energy storage capacitor when receiving the excitation pulse. When the second analog switch is turned on, the two ends of the energy storage capacitor are grounded, the energy storage capacitor is in a discharge state, and the reference voltage V DAC Reset to initial voltage V th .

[0072] The working process of the measurement circuit includes: when V1 is greater than V2, the first diode is reverse-cut off, the second diode is forward-biased, the energy storage capacitor is in a charging state, and the voltage V2 increases; when V1 is equal to V2, the inverting input terminal of the first operational amplifier unit and the output terminal of the second operational amplifier unit are in a virtual disconnection state; when V1 is less than V2, the first diode is forward-biased, the second diode is reverse-biased, and the voltage V2 remains unchanged.

[0073] The measuring circuit further includes an operating unit for operating the measuring circuit according to the reference voltage V DAC Calculate the peak voltage of the partial discharge signal. The operation unit, for example, converts the final output reference voltage V according to the amplification ratio of the operational amplifier unit. DACThe present invention can also directly output the final maintained reference voltage V without including the calculation unit. DAC as the peak voltage.

[0074] The measurement circuit also includes a radio frequency bandpass filter, a low-noise amplifier, and a detector, which are located between the main circuit and the non-inverting input of the first operational amplifier unit. When a UHF partial discharge signal is received from the main circuit, the radio frequency bandpass filter filters the UHF partial discharge signal, the low-noise amplifier performs low-noise amplification on the filtered signal to increase the signal amplitude, and the detector detects the amplified signal, converting it into a processable partial discharge signal for output.

[0075] In this embodiment, if Figure 9 The RF bandpass filter can retain signals in the 150MHz-530MHz frequency band of ultra-high frequency partial discharge signals, while retaining the main partial discharge signals while removing electromagnetic interference generated by other power equipment and clutter interference from wireless communications. The RF bandpass filter includes seven capacitors and seven inductors. The capacitances of the seven capacitors are C3, C4, C5, C6, C7, C8, and C9, and the inductances of the seven inductors are L1, L2, L3, L4, L5, L6, and L7, respectively. C3 = C9 = 2pF, C4 = C8 = 13pF, C5 = C6 = C7 = 9pF, L1 = L7 = 100nH, L2 = L6 = 15nH, and L3 = L4 = L5 = 24nH. The input and output ends of the RF bandpass filter both adopt a 50Ω matching design.

[0076] like Figure 10 The low noise amplifier uses an AD8354 chip, for example, which has a noise figure of 4.2, an operating frequency band of 1MHz-2.7GHz, and a gain of 20dB. The AD8354 chip includes four peripheral capacitors, wherein the capacitance of the four peripheral capacitors is C 10 、C 11 、C 12 and C 13 , C 10 =C 11 =1nF, C 12 =100pF,C 13 =470pF.

[0077] like Figure 11The detector uses the ADL5904 chip, for example. The ADL5904 chip has an RMS power detection function, an operating frequency range from DC to 6GHz, and has the characteristics of a wide frequency range, fast response speed, and low power consumption. It can output a lower frequency and smoother partial discharge signal. The peripheral components of the ADL5904 chip include four capacitors and two resistors, where the capacitance of the four capacitors is C 14 、C 15 、C 16 and C 17 , the resistance values of the two resistors are R1 and R2, C 14 =470nF,R1=82.5Ω,C 15 =100nF, R2=4.02Ω, C 16 =100nF, C 17 =100pF. The peak voltage of the partial discharge signal obtained after the ultra-high frequency partial discharge signal is filtered, amplified and detected by the radio frequency bandpass filter, low noise amplifier and detector is 1V. Example 3

[0078] This embodiment further discloses the working process of the single chip microcomputer. The embedded program flow of the single chip microcomputer is as follows: Figure 12 As shown, it includes three stages: DAC configuration and system initialization, data acquisition, and data processing and storage.

[0079] The single-chip microcontroller includes a first converter and a second converter (two DAC digital-to-analog converters). In this embodiment, the single-chip microcontroller is, for example, an STM32L476 single-chip microcontroller. The STM32L476 single-chip microcontroller can be configured in 8-bit digital mode during the initialization phase. The DAC clock frequency is configured to 80MHz, the reference voltage is 3.3V, the increment step size β is set to 2, and the voltage step size is 2 / 256*3.3V=25.78mV. The variable d is the reference voltage V of the second converter. DAC The figure shows that the initial voltage of the second converter V th and the noise voltage of the first converter V ref According to actual conditions, in this embodiment, the variable d is set to a value of 0E, corresponding to a reference voltage of approximately 0.2V.

[0080] like Figure 5 , the second converter outputs the reference voltage V DAC Compare with the output voltage V2 of the second operational amplifier unit, when the reference voltage V DAC When it is less than V2, the second comparator outputs a high level, and the variable d increases by 2 until the reference voltage V output by the second converter reaches DACWhen V is greater than V2, the second comparator outputs a low level, causing the monostable multivibrator unit to output an excitation pulse (high level) set by the adjustment capacitor and adjustment resistor. The second analog switch closes, discharging the energy storage capacitor. The monostable multivibrator unit is, for example, a 74LVC123. In this embodiment, no arithmetic unit is included. The variable d directly output by the second converter is the peak voltage of the partial discharge signal. Variable d is stored in array D, completing peak voltage acquisition.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring partial discharge peak value based on a single chip microcomputer, characterized in that: The partial discharge peak measurement circuit based on the single chip microcomputer includes a first operational amplifier unit, an energy storage capacitor, a first diode, a second diode, a second operational amplifier unit, a single chip microcomputer, a first analog switch, a monostable multivibrator unit and a second analog switch; The non-inverting input terminal of the first operational amplifier unit is connected to the main circuit; The first diode is used to connect the inverting input terminal and the output terminal of the first operational amplifier unit in series; The non-inverting input terminal of the second operational amplifier unit is connected to the output terminal of the first operational amplifier unit through the second diode and the first analog switch; the inverting input terminal of the first operational amplifier unit is connected to the output terminal of the second operational amplifier unit through a current limiting resistor, and the inverting input terminal of the second operational amplifier unit is connected to the output terminal of the second operational amplifier unit; The energy storage capacitor is used to receive the partial discharge signal and charge, one end of the energy storage capacitor is connected to the output end of the second diode, and the other end is grounded; the second analog switch is connected in parallel with the energy storage capacitor; The single chip microcomputer includes a noise removal unit and a peak measurement unit; The denoising unit is used to compare the voltage V1 of the output signal of the first operational amplifier unit with the noise voltage V ref The peak measurement unit is used to compare the voltage V2 of the output signal of the second operational amplifier unit with the reference voltage V DAC ; The method comprises the following steps: Step 1: The non-inverting input terminal of the first operational amplifier unit collects the partial discharge signal, the first operational amplifier unit responds to the partial discharge signal and generates an output signal, and the inverting input terminal of the first operational amplifier unit receives the output signal of the second operational amplifier unit; Step 2: Compare the voltage V1 of the output signal of the first op amp unit with the noise voltage V ref , if V1 is greater than V ref , the first analog switch connects the first operational amplifier unit and the energy storage capacitor, and the process proceeds to step 3; otherwise, the first operational amplifier unit and the energy storage capacitor are disconnected, and the process returns to step 1; Step 3: Compare the voltage V1 of the output signal of the first operational amplifier unit with the voltage V2 of the output signal of the second operational amplifier unit. When V1 is greater than V2, proceed to step 4. When V1 is less than V2, proceed to step 7. Otherwise, the inverting input terminal of the first operational amplifier unit and the output terminal of the second operational amplifier unit are in a virtual disconnect state, and return to step 1. Step 4: The first diode is reverse-blocked, the second diode is forward-biased, the energy storage capacitor is in a charging state, and the voltage V2 increases; Step 5: Compare V2 with the reference voltage V DAC , if V2 is greater than or equal to V DAC , V DAC Increment, store the incremented V DAC , return to step 1, otherwise go to step 6; Step 6: The monostable multivibrator unit generates an excitation pulse. When the second analog switch receives the excitation pulse, it connects both ends of the energy storage capacitor to the ground. The energy storage capacitor is in a discharge state and outputs V DAC And calculate the peak voltage of the partial discharge signal, and return to step 1; Step 7: The first diode is forward-biased, the second diode is reverse-biased, the voltage V2 remains unchanged, and the process returns to step 1.

2. A measurement circuit for implementing the method for measuring partial discharge peak value based on a single chip microcomputer according to claim 1, characterized in that: include: A first operational amplifier unit, wherein a non-inverting input terminal of the first operational amplifier unit is connected to a main circuit for collecting partial discharge signals; Energy storage capacitor, used to receive partial discharge signals and charge; a first diode, used for connecting in series the inverting input terminal and the output terminal of the first operational amplifier unit; a second diode, the second diode being located between the output end of the first operational amplifier unit and the energy storage capacitor; a second operational amplifier unit, wherein a non-inverting input terminal of the second operational amplifier unit is connected to an output terminal of the first operational amplifier unit through a second diode; The single chip microcomputer includes a denoising unit and a peak measurement unit. The denoising unit is used to compare the voltage V1 of the output signal of the first operational amplifier unit with the noise voltage V ref The peak measurement unit is used to compare the voltage V2 of the output signal of the second operational amplifier unit with the reference voltage V DAC ; The first analog switch is used when V1 is greater than V ref When the output terminal of the first operational amplifier unit and the energy storage capacitor are turned on; Monostable multivibrator unit, used when V2 is less than V DAC Output an excitation pulse when The second analog switch is used to ground both ends of the energy storage capacitor when receiving an excitation pulse, wherein: When V1 is greater than V2, the first diode is reverse-cut off, the second diode is forward-biased, the energy storage capacitor is in a charging state, and the voltage V2 increases. When V1 is equal to V2, the inverting input terminal of the first operational amplifier unit and the output terminal of the second operational amplifier unit are in a virtual disconnect state. When V1 is less than V2, the first diode is forward-biased, the second diode is reverse-biased, and the voltage V2 remains unchanged.

3. The measuring circuit according to claim 2, characterized in that V2 is greater than or equal to V DAC When the peak measurement unit increases by V DAC , and store the incremented V DAC , V2 is less than V DAC When the peak measurement unit outputs V DAC Then V DAC Reset to initial voltage V th .

4. The measuring circuit according to claim 2, characterized in that The inverting input terminal of the first operational amplifier unit is connected to the output terminal of the second operational amplifier unit via a current limiting resistor, and the inverting input terminal of the second operational amplifier unit is connected to the output terminal of the second operational amplifier unit.

5. The measurement circuit according to claim 2, characterized in that The denoising unit includes a first comparator and a first converter, the first converter outputs a noise voltage to the first comparator, the peak measurement unit includes a second comparator and a second converter, the second converter outputs a reference voltage to the second comparator, and when the second comparator is at a high level, the second converter increases the reference voltage.

6. The measurement circuit according to claim 2, characterized in that The first diode and the second diode are Schottky diodes.

7. The measurement circuit according to claim 2, characterized in that It also includes an operation unit for DAC Calculate the peak voltage of the partial discharge signal.

8. The measurement circuit according to claim 2, characterized in that It also includes a radio frequency band pass filter, a low noise amplifier, and a detector, which are located between the main loop and the in-phase input end of the first operational amplifier unit.

9. The measurement circuit according to claim 2, characterized in that The monostable multivibrator unit has an adjusting resistor and an adjusting capacitor, and the duration of the excitation pulse is controlled according to the adjusting resistor and the adjusting capacitor.

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