Dynamic tracking and interference elimination high-frequency coupling partial discharge detection device and method

Abstract

The invention relates to a dynamic tracking and interference elimination high-frequency coupling partial discharge detection device and method, which comprises a high-frequency current transformer, a protection module, a power frequency extraction module, a high-frequency extraction module, a phase-locked synchronization unit, a channel conditioning module, a CPU processing unit and a wireless communication unit; the output end of the high-frequency current transformer is connected to the input end of the protection module; the output end of the protection module is divided into two paths, one path passes through the power frequency extraction module and the phase-locked synchronization unit in sequence to one input end of the CPU processing unit; the other path passes through the high-frequency extraction module and the channel conditioning module in sequence to the other input end of the CPU processing unit; the output end of the CPU processing unit is electrically connected to the input end of the wireless communication unit; the invention has reasonable design, compact structure and convenient use.

Description

Technical Field

[0001] The present invention relates to a dynamic tracking and interference elimination high-frequency coupling partial discharge detection device and method, belonging to the field of detection technology. The present invention is suitable for live detection partial discharge test of converter substation, and is mainly used for live detection of partial discharge of running converter transformer under different converter station operating environments. The device can eliminate the interference generated by the valve hall of the converter station, improve the anti-interference ability of high-frequency partial discharge detection, improve the efficiency of live partial discharge test, and ensure that the live detection data of partial discharge is accurate and highly sensitive. Background Art

[0002] Live partial discharge test is one of the important items for converter transformer, especially the insulation status detection of converter transformer. When conducting partial discharge test of converter transformer on site, the converter station is often partially or fully energized. The background interference of partial discharge test is large and its composition is much more complicated than that of AC substation, which brings great interference to the on-site partial discharge test of converter transformer.

[0003] The on-site interference mainly comes from the electromagnetic noise interference generated by the converter valve, which is the main source of interference in the DC high-voltage converter station. The electromagnetic interference caused during the operation of the converter valve is generated during the triggering and shutting down of the thyristor of the converter valve body. This continuous interference noise is the main source of interference in the electromagnetic interference environment of the converter station. During the commutation process of the converter valve, a rapid voltage breakdown process will occur in the gate tube. The drastic change of the voltage at the converter valve end is accompanied by a rapid increase in the current flowing through the converter valve. A series of transient electromagnetic noises generated by the converter valve switch propagate along the commutation circuit and enter sensitive equipment through direct electrical connection or coupling, resulting in the phenomenon of conducted electromagnetic interference. There are 12 pulses of interference generated in the converter station. The pulsating interference signal is radiated to the partial discharge measurement system through the earth and space, resulting in excessive background amplitude of partial discharge measurement. The partial discharge pulse is masked by the 12 pulsating interference signal, and the real partial discharge signal cannot be extracted, thereby causing errors in partial discharge measurement. At present, artificial technical means such as windowing are generally used to eliminate background interference, and the judgment of test results is relatively subjective. Summary of the invention

[0004] The technical problem to be solved by the present invention is generally to provide a dynamic tracking and interference elimination high-frequency coupling partial discharge detection device and method. In view of the above situation, this patent analyzes the typical interference signal categories, interference signal sources, and interference signal transmission paths of the converter transformer partial discharge test, clarifies the characteristics, amplitude-frequency characteristics, and statistical spectrum characteristics of typical interference signals, overcomes the shortcomings of existing interference elimination technology, ensures the accuracy of partial discharge measurement, and improves the efficiency of on-site partial discharge tests of converter transformers.

[0005] To solve the above problems, the technical solution adopted by the present invention is:

[0006] A dynamic tracking and interference elimination high-frequency coupled partial discharge detection device, comprising a high-frequency current transformer, a protection module, a power frequency extraction module, a high-frequency extraction module, a phase-locked synchronization unit, a channel conditioning module, a CPU processing unit and a wireless communication unit;

[0007] The output end of the high-frequency current transformer is connected to the input end of the protection module; the output end of the protection module is divided into two paths, one path passes through the power frequency extraction module and the phase-locked synchronization unit in sequence to the first input end of the CPU processing unit; the other path passes through the high-frequency extraction module and the channel conditioning module in sequence to the other input end of the CPU processing unit;

[0008] The output end of the CPU processing unit is electrically connected to the input end of the wireless communication unit;

[0009] The high-frequency current transformer couples the high-frequency current signal and the power-frequency current signal simultaneously;

[0010] After the high-frequency current signal and the power frequency current signal pass through the protection module, the power frequency extraction module extracts the effective power frequency current signal. The power frequency current signal is then filtered and amplified by the rectifier and amplifier, and then the signal is input into the phase-locked synchronization unit.

[0011] The phase-locked synchronization unit shapes the power frequency current to obtain a zero-phase trigger signal. At the same time, according to the characteristics of the pulsating interference signal, the synchronization signal is divided into N pulses with a time interval. The phase-locked synchronization unit phase-locks the N pulses; the N-pulse phase-locked signal is input to the CPU processing unit;

[0012] On the other hand, the high-frequency extraction module separates the high-frequency current signal. The separated high-frequency current signal includes the pulsation interference signal and the insulation discharge signal inside the converter transformer. The high-frequency current signal is amplified by the channel conditioning module, and the amplified high-frequency signal is input into the CPU processing unit.

[0013] The CPU processing unit obtains the high-frequency signal and the N-pulse phase signal at the same time; the high-frequency signal includes the partial discharge signal and the interference signal; the CPU processing unit first converts the high-frequency signal into a digital signal, and then uses the N-pulse phase signal to perform interpolation operation on the digitized high-frequency signal, and eliminates the interference signal in the high-frequency signal through interpolation to obtain the required partial discharge signal; finally, the required partial discharge signal transmits the data to the wireless communication module through the serial port, and the wireless communication module transmits the partial discharge wirelessly to the background system.

[0014] As a further improvement of the above technical solution:

[0015] High-frequency pulse current signals include converter station pulsation interference signals and converter transformer internal partial discharge signals;

[0016] The protection module includes a gas discharge tube;

[0017] The coupled high-frequency current signal and the power frequency current signal are separated into the power frequency current through the power frequency extraction module, and the separated power frequency current is outputted into 12 equally spaced pulses through the phase-locked synchronization module; in the power frequency extraction module:

[0018] The power frequency current extraction circuit includes power frequency resistors R1, R2 and power frequency capacitor C1; an output end of the power frequency resistor R1 is grounded through the power frequency capacitor C1, and an output end of the power frequency resistor R1 is output through the power frequency resistor R2. The filter cutoff frequency band of the circuit is 100Hz, so that frequency signals above 100Hz can be filtered out and 50Hz power frequency signals can be retained;

[0019] The power frequency amplifier U1 is a low-noise high-gain operational amplifier. The model of the power frequency amplifier U1 is AD301. Its input terminal 1 is connected to the output end of the power frequency resistor R2 and grounded through the reverse power frequency diode D6, and its input terminal 2 is grounded; its output terminal 4 is connected to 33V, and its output terminal 3 is grounded through the power frequency resistor R5 to limit the voltage; the 50Hz power frequency signal is amplified 200 times by the power frequency amplifier U1 to ensure that the power frequency signal can be effectively detected;

[0020] The model of the power frequency integrated circuit U2 is LM311, and the frequency response speed of the LM311 chip is kHz. The power frequency signal is conditioned into a pulse signal by the power frequency integrated circuit U2, and the amplified power frequency signal is output to the input terminal 2 of the power frequency integrated circuit U2 through the output terminal 3 of the power frequency amplifier U1; the input terminal 4 of the power frequency integrated circuit U2 is grounded, and the input terminal 3 of the power frequency integrated circuit U2 is grounded through the resistor R3 and connected to the power supply 33V through the resistor R4; the output terminal 1 of the power frequency integrated circuit U2 is grounded, and the output terminal 7 is connected to the power supply 33V through the resistor R6; the output terminal 7 is connected to the input terminal of the CPU processing unit through the power frequency resistor R2;

[0021] The model of the power frequency chip U3 is CD4069. The input terminal 2 of the power frequency chip U3 is grounded through the power frequency capacitor C2. The input terminal 2 of the power frequency chip U3 is connected to the output terminal 7 of the power frequency integrated circuit U2 through the power frequency resistor R7.

[0022] The pulse signal is output to the input terminal 2 of the power frequency chip U3 through the output terminal 7 of the integrated circuit U2, the input terminal 6 of the power frequency chip U3 is grounded, and the input terminal 7 of the power frequency chip U3 is connected to the power supply 33V through the power frequency resistor R8; the terminal 5 of the power frequency chip U3 is grounded through the power frequency capacitor C4, and the output terminal 3 of the power frequency chip U3 is grounded through the power frequency resistor R10 and output to the CPU processing unit through the power frequency capacitor C5;

[0023] The power frequency chip U3 divides the pulse signal into 12 pulse signals with equal time intervals. The pulse time interval is 1.67ms. After frequency division, the 12 pulse signals are transmitted to the CPU processing unit.

[0024] Another route is to separate the high-frequency signal through the high-frequency extraction module, and the separated high-frequency current signal is conditioned, filtered and amplified by the channel conditioning module;

[0025] The bandpass filter includes a high-frequency boosting transformer T1 and a high-frequency capacitor C1. The bandpass filter frequency band is 1MHz-50MHz, wherein the high-frequency boosting transformer T1 boosts the signal by 2 times;

[0026] The high-frequency amplifier circuit includes a high-frequency amplifier U1, a high-frequency capacitor C2 and a high-frequency resistor R3; the positive input terminal 3 of the high-frequency amplifier U1 is grounded through the high-frequency capacitor C3, and the negative input terminal 2 is grounded through the high-frequency inductor R2. The high-frequency capacitor C2 and the high-frequency resistor R3 are connected in parallel between the output terminal 6 and the negative input terminal 2; the high-frequency amplifier circuit amplifies the high-frequency signal by 100 times;

[0027] The high-frequency detection circuit includes a high-frequency resistor R5, a high-frequency resistor R6, a high-frequency diode D1 and a high-frequency capacitor C6; the output terminal 6 of the high-frequency amplifier U1 is connected through the high-frequency capacitor C5, the output terminal of the high-frequency capacitor C5 is grounded through the high-frequency resistor R5 and the high-frequency resistor R6 respectively, and the output terminal of the high-frequency capacitor C5 is output through the high-frequency diode D1; the output terminal of the high-frequency diode D1 is grounded through the high-frequency capacitor C6 and the high-frequency resistor R7 respectively; the high-frequency detection circuit reduces the frequency of the high-frequency signal to 20kHz;

[0028] The follower circuit includes a high-frequency amplifier U2 and a high-frequency resistor R8; the output end of the high-frequency diode D1 is electrically connected to the positive input end 3 of the high-frequency amplifier U2; the output end 6 of the high-frequency amplifier U2 is electrically connected to the input end of the CPU processing unit through the high-frequency resistor R8;

[0029] The high-frequency amplifier U2 is AD831, the high-frequency resistor R8 has a resistance value of 50 ohms, and the following circuit ensures impedance matching; the conditioned high-frequency signal is input to the CPU processing unit;

[0030] The CPU processing unit synchronously collects the 12-pulse signal and the conditioned high-frequency signal and performs difference calculation. After the calculation is completed, the CPU processing unit eliminates the pulsation interference signal of the converter station and retains the partial discharge signal inside the converter transformer. The CPU processing unit transmits the interference-free partial discharge signal wirelessly to the background analysis system through the wireless communication module.

[0031] A dynamic tracking and interference elimination high-frequency coupled partial discharge detection method, the method comprising the following steps:

[0032] Step 1, first, the high-frequency current transformer couples the high-frequency current signal and the power-frequency current signal at the same time; then, the high-frequency current signal and the power-frequency current signal pass through the protection module; secondly, the coupled high-frequency current signal and the power-frequency current signal are separated from the power-frequency current through the power-frequency extraction module, and the separated power-frequency current passes through the phase-locked synchronization module to output 12 equally spaced pulses; again, after frequency division, the 12 pulse signals are transmitted to the CPU processing unit, and at the same time, the high-frequency extraction module separates the high-frequency signal, and the separated high-frequency current signal passes through the channel conditioning module to condition, filter, and amplify the signal, and the conditioned high-frequency signal is input to the CPU processing unit;

[0033] Step 2: The CPU processing unit synchronously collects the 12-pulse signal and the conditioned high-frequency signal and performs difference calculation. After the calculation is completed, the CPU processing unit eliminates the pulsation interference signal of the converter station and retains the local discharge signal inside the converter transformer. The CPU processing unit wirelessly transmits the local discharge signal with interference eliminated to the background analysis system through the wireless communication module.

[0034] The present invention has reasonable design, low cost, strong durability, safety and reliability, simple operation, time-saving and labor-saving, money-saving, compact structure and convenient use. In the field application of the existing high-frequency partial discharge detection device, the interference signal of the valve hall cannot be eliminated, and the real discharge signal is covered by the interference, resulting in inaccurate measurement, and the detection value cannot be read and recorded. The dynamic tracking and interference elimination high-frequency coupling partial discharge detection device can effectively eliminate the interference on the field during the field detection, extract the real internal partial discharge signal, ensure the accuracy of the partial discharge measurement, and improve the efficiency of the on-site partial discharge test of the converter transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a working principle diagram of the present invention.

[0036] Figure 2 It is a schematic diagram of the CPU algorithm principle implementation of the present invention.

[0037] Figure 3 It is a circuit diagram of an industrial frequency extraction module and a phase-locked synchronization module of the present invention.

[0038] Figure 4 It is a high-frequency signal conditioning circuit diagram of the present invention.

[0039] Figure 5 It is a schematic diagram of an example of the use structure of the present invention.

[0040] Figure 6 It is an exemplary schematic diagram of the present invention. DETAILED DESCRIPTION

[0041] like Figure 1-6The working principle of the device of the present invention is as follows Figure 1 As shown, the present invention includes a high-frequency current transformer, a protection module, a power frequency extraction module, a high-frequency extraction module, a phase-locked synchronization unit, a channel conditioning module, a CPU processing unit and a wireless communication unit;

[0042] The output end of the high-frequency current transformer is connected to the input end of the protection module; the output end of the protection module is divided into two paths, one path passes through the power frequency extraction module and the phase-locked synchronization unit in sequence to the first input end of the CPU processing unit; the other path passes through the high-frequency extraction module and the channel conditioning module in sequence to the other input end of the CPU processing unit;

[0043] The output end of the CPU processing unit is electrically connected to the input end of the wireless communication unit;

[0044] The high-frequency current transformer couples the high-frequency current signal and the power-frequency current signal simultaneously;

[0045] After the high-frequency current signal and the industrial frequency current signal pass through the protection module, the protection module prevents the device from being impacted by overvoltage and overcurrent.

[0046] In one of the channels, the power frequency extraction module extracts the effective power frequency current signal, and the power frequency current signal is filtered and amplified by the rectifier and amplifier, and then the signal is input into the phase-locked synchronization unit;

[0047] The phase-locked synchronization unit shapes the power frequency current to obtain a zero-phase trigger signal. At the same time, according to the characteristics of the pulsating interference signal, the synchronization signal is divided into 12 pulses with a time interval of 1.67ms. The phase-locked synchronization unit phase-locks the 12 pulses; the 12-pulse phase-locked signal is input to the CPU processing unit;

[0048] On the other hand, the high-frequency extraction module separates the high-frequency current signal. The separated high-frequency current signal includes the pulsation interference signal and the insulation discharge signal inside the converter transformer. The high-frequency current signal is amplified by the channel conditioning module to improve the sensitivity of high-frequency signal detection. The amplified high-frequency signal is input into the CPU processing unit.

[0049] CPU data processing diagram Figure 2 As shown, the CPU processing unit obtains the high-frequency signal and the 12-pulse phase signal at the same time; the high-frequency signal includes the partial discharge signal and the interference signal; the CPU processing unit first converts the high-frequency signal into a digital signal, and then uses the 12-pulse phase signal to interpolate the digitized high-frequency signal, and eliminates the interference signal in the high-frequency signal through interpolation to obtain the real partial discharge signal; finally, the real partial discharge signal transmits the data to the wireless communication module through the serial port, and the wireless communication module transmits the partial discharge wirelessly to the background system.

[0050] Working principle and implementation of the present invention:

[0051] Circuit diagram Figure 1-3 As shown, the present invention couples current signals through high-frequency current sensors (current transformers), and the current signals include power frequency current signals and high-frequency pulse current signals, wherein the high-frequency pulse current signals include converter station pulsation interference signals and converter transformer internal partial discharge signals;

[0052] The current signal passes through the protection module, which includes gas discharge tubes TVP1 and TVP2; the gas discharge tubes provide limiting protection to prevent excessive induced voltage from damaging subsequent electronic devices.

[0053] The current signal is separated into power frequency current by the power frequency extraction module, and the separated power frequency current is outputted into 12 equally spaced pulses by the phase-locked synchronization module; in the power frequency extraction module:

[0054] The power frequency current extraction circuit includes power frequency resistors R1, R2 and power frequency capacitor C1; an output end of the power frequency resistor R1 is grounded through the power frequency capacitor C1, and an output end of the power frequency resistor R1 is output through the power frequency resistor R2. The filter cutoff frequency band of the circuit is 100Hz, so that frequency signals above 100Hz can be filtered out and 50Hz power frequency signals can be retained;

[0055] The power frequency amplifier U1 is a low-noise high-gain operational amplifier. The model of the power frequency amplifier U1 is AD301. Its input terminal 1 is connected to the output end of the power frequency resistor R2 and grounded through the reverse power frequency diode D6, and its input terminal 2 is grounded; its output terminal 4 is connected to 33V, and its output terminal 3 is grounded through the power frequency resistor R5 to limit the voltage; the 50Hz power frequency signal is amplified 200 times by the power frequency amplifier U1 to ensure that the power frequency signal can be effectively detected;

[0056] The model of the power frequency integrated circuit U2 is LM311, and the frequency response speed of the LM311 chip is kHz. The power frequency signal is conditioned into a pulse signal by the power frequency integrated circuit U2, and the amplified power frequency signal is output to the input terminal 2 of the power frequency integrated circuit U2 through the output terminal 3 of the power frequency amplifier U1; the input terminal 4 of the power frequency integrated circuit U2 is grounded, and the input terminal 3 of the power frequency integrated circuit U2 is grounded through the resistor R3 and connected to the power supply 33V through the resistor R4; the output terminal 1 of the power frequency integrated circuit U2 is grounded, and the output terminal 7 is connected to the power supply 33V through the resistor R6; the output terminal 7 is connected to the input terminal of the CPU processing unit through the power frequency resistor R2;

[0057] The model of the power frequency chip U3 is CD4069. The input terminal 2 of the power frequency chip U3 is grounded through the power frequency capacitor C2. The input terminal 2 of the power frequency chip U3 is connected to the output terminal 7 of the power frequency integrated circuit U2 through the power frequency resistor R7.

[0058] The pulse signal is output to the input terminal 2 of the power frequency chip U3 through the output terminal 7 of the integrated circuit U2, the input terminal 6 of the power frequency chip U3 is grounded, and the input terminal 7 of the power frequency chip U3 is connected to the power supply 33V through the power frequency resistor R8; the terminal 5 of the power frequency chip U3 is grounded through the power frequency capacitor C4, and the output terminal 3 of the power frequency chip U3 is grounded through the power frequency resistor R10 and output to the CPU processing unit through the power frequency capacitor C5;

[0059] The industrial frequency chip U3 divides the pulse signal into 12 pulse signals with equal time intervals. The pulse time interval is 1.67ms. After frequency division, the 12 pulse signals are transmitted to the CPU processing unit.

[0060] Circuit diagram Figure 4 As shown, another route separates the high-frequency signal through the high-frequency extraction module, and the separated high-frequency current signal is conditioned, filtered, and amplified by the channel conditioning module.

[0061] The bandpass filter includes a high-frequency boosting transformer T1 and a high-frequency capacitor C1. The bandpass filter frequency band is 1MHz-50MHz. The high-frequency boosting transformer T1 can boost the signal by 2 times. Its frequency band characteristic is wide-band, and it can also play an isolation and filtering role.

[0062] The high-frequency amplifier circuit includes a high-frequency amplifier U1, a high-frequency capacitor C2 and a high-frequency resistor R3; the positive input terminal 3 of the high-frequency amplifier U1 is grounded through the high-frequency capacitor C3, the negative input terminal 2 is grounded through the high-frequency inductor R2, and the high-frequency capacitor C2 and the high-frequency resistor R3 are connected in parallel between the output terminal 6 and the negative input terminal 2; the high-frequency amplifier circuit amplifies the high-frequency signal 100 times.

[0063] The high-frequency detection circuit includes a high-frequency resistor R5, a high-frequency resistor R6, a high-frequency diode D1 and a high-frequency capacitor C6; the output terminal 6 of the high-frequency amplifier U1 is connected through the high-frequency capacitor C5, the output terminal of the high-frequency capacitor C5 is grounded through the high-frequency resistor R5 and the high-frequency resistor R6 respectively, and the output terminal of the high-frequency capacitor C5 is output through the high-frequency diode D1; the output terminal of the high-frequency diode D1 is grounded through the high-frequency capacitor C6 and the high-frequency resistor R7 respectively; the high-frequency detection circuit reduces the frequency of the high-frequency signal to about 20kHz. The purpose of reducing the frequency is to ensure that the peak value of the high-frequency signal can be fully collected under the premise that the sampling rate of the AD converter of the CPU processing unit is 1MHz, thereby reducing the cost of the CPU processing unit and making the circuit more widely applicable.

[0064] The follower circuit includes a high-frequency amplifier U2 and a high-frequency resistor R8; the output end of the high-frequency diode D1 is electrically connected to the positive input end 3 of the high-frequency amplifier U2; the output end 6 of the high-frequency amplifier U2 is electrically connected to the input end of the CPU processing unit through the high-frequency resistor R8;

[0065] The high-frequency amplifier U2 is AD831, the high-frequency resistor R8 has a resistance value of 50 ohms, and the following circuit ensures impedance matching. The conditioned high-frequency signal is input to the CPU processing unit.

[0066] The CPU processing unit synchronously collects the 12-pulse signal and the conditioned high-frequency signal and performs difference calculation. After the calculation is completed, the CPU processing unit eliminates the pulsation interference signal of the converter station and retains the partial discharge signal inside the converter transformer. The CPU processing unit transmits the interference-free partial discharge signal wirelessly to the background analysis system through the wireless communication module.

[0067] The T1 transformer has a wide frequency band characteristic, which plays an isolation and filtering role. The channel conditioning module amplifies the high-frequency signal by 100 times and reduces the frequency of the high-frequency signal to about 20kHz to ensure the integrity of the sampling of the CPU processing unit. The CPU processing unit performs interpolation operations, eliminates interference signals, extracts the true discharge signal, and transmits data through the wireless communication module. The T1 transformer uses high permeability and low loss magnetic materials to ensure the simultaneous coupling of high-frequency current signals and industrial frequency current signals.

[0068] like Figure 5-Figure 6 The structure shown is merely an illustration of a physical diagram and is not intended to be limiting.

[0069] The present invention is fully described for a clearer disclosure, and the prior art is not listed one by one.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some of the technical features therein with equivalents; it is obvious for those skilled in the art to combine multiple technical solutions of the present invention. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dynamic tracking and interference elimination high frequency coupled partial discharge detection method, characterized in that: The method comprises the following steps, Step 1: First, the high-frequency current transformer couples the high-frequency current signal and the power frequency current signal at the same time; then, the high-frequency current signal and the power frequency current signal pass through the protection module; secondly, the coupled high-frequency current signal and the power frequency current signal are separated into the power frequency current through the power frequency extraction module, and the separated power frequency current is outputted into 12 equally spaced pulses through the phase-locked synchronization module; Again, after frequency division, the 12-pulse signal is transmitted to the CPU processing unit. At the same time, the high-frequency extraction module separates the high-frequency signal. The separated high-frequency current signal is conditioned, filtered, and amplified by the channel conditioning module. The conditioned high-frequency signal is input to the CPU processing unit. Step 2: The CPU processing unit synchronously collects the 12 pulse signals and the conditioned high-frequency signals, and performs difference calculation. After the calculation is completed, the CPU processing unit eliminates the pulsation interference signal of the converter station and retains the partial discharge signal inside the converter transformer. The CPU processing unit transmits the interference-free partial discharge signal to the background analysis system through the wireless communication module; The method uses a dynamic tracking and interference elimination high-frequency coupled partial discharge detection device, which includes a high-frequency current transformer, a protection module, a power frequency extraction module, a high-frequency extraction module, a phase-locked synchronization unit, a channel conditioning module, a CPU processing unit and a wireless communication unit; The output end of the high-frequency current transformer is connected to the input end of the protection module; the output end of the protection module is divided into two paths, one path passes through the power frequency extraction module and the phase-locked synchronization unit in sequence to an input end of the CPU processing unit; the other path passes through the high-frequency extraction module and the channel conditioning module in sequence to the other input end of the CPU processing unit; The output end of the CPU processing unit is electrically connected to the input end of the wireless communication unit; The high-frequency current transformer couples the high-frequency current signal and the power-frequency current signal simultaneously; After the high-frequency current signal and the power frequency current signal pass through the protection module, the power frequency extraction module extracts the effective power frequency current signal. The power frequency current signal is then filtered and amplified by the rectifier and amplifier, and then the signal is input into the phase-locked synchronization unit. The phase-locked synchronization unit shapes the power frequency current to obtain a zero-phase trigger signal. At the same time, according to the characteristics of the pulsating interference signal, the synchronization signal is divided into N pulses with a time interval. The phase-locked synchronization unit phase-locks the N pulses; the N-pulse phase-locked signal is input to the CPU processing unit; On the other hand, the high-frequency extraction module separates the high-frequency current signal. The separated high-frequency current signal includes the pulsation interference signal and the insulation discharge signal inside the converter transformer. The high-frequency current signal is amplified by the channel conditioning module, and the amplified high-frequency signal is input into the CPU processing unit. The CPU processing unit obtains the high-frequency signal and the N-pulse phase signal at the same time; the high-frequency signal includes the partial discharge signal and the interference signal; the CPU processing unit first converts the high-frequency signal into a digital signal, and then uses the N-pulse phase signal to perform interpolation operation on the digitized high-frequency signal, and eliminates the interference signal in the high-frequency signal through interpolation to obtain the required partial discharge signal; finally, the required partial discharge signal transmits the data to the wireless communication module through the serial port, and the wireless communication module transmits the partial discharge wirelessly to the background system; High-frequency pulse current signals include converter station pulsation interference signals and converter transformer internal partial discharge signals; The protection module includes a gas discharge tube; The coupled high-frequency current signal and the power frequency current signal are separated into the power frequency current through the power frequency extraction module, and the separated power frequency current is outputted into 12 equally spaced pulses through the phase-locked synchronization module; in the power frequency extraction module: The power frequency current extraction circuit includes power frequency resistors R1, R2 and power frequency capacitor C1; an output end of the power frequency resistor R1 is grounded through the power frequency capacitor C1, and an output end of the power frequency resistor R1 is output through the power frequency resistor R2. The filter cutoff frequency band of the circuit is 100Hz, so that frequency signals above 100Hz can be filtered out and 50Hz power frequency signals can be retained; The power frequency amplifier U1 is a low-noise high-gain operational amplifier. The model of the power frequency amplifier U1 is AD301. Its input terminal 1 is connected to the output end of the power frequency resistor R2 and grounded through the reverse power frequency diode D6, and its input terminal 2 is grounded; its output terminal 4 is connected to 33V, and its output terminal 3 is grounded through the power frequency resistor R5 to limit the voltage; the 50 Hz power frequency signal is amplified 200 times by the power frequency amplifier U1 to ensure that the power frequency signal can be effectively detected; The model of the industrial frequency integrated circuit U2 is LM311, and the frequency response speed of the LM311 chip is kHz. The industrial frequency signal is conditioned into a pulse signal by the industrial frequency integrated circuit U2, and the amplified industrial frequency signal is output to the input terminal 2 of the industrial frequency integrated circuit U2 through the output terminal 3 of the industrial frequency amplifier U1; the input terminal 4 of the industrial frequency integrated circuit U2 is grounded, and the input terminal 3 of the industrial frequency integrated circuit U2 is grounded through the resistor R3 and connected to the power supply 33V through the resistor R4; the output terminal 1 of the industrial frequency integrated circuit U2 is grounded, and the output terminal 7 is connected to the power supply 33V through the resistor R6; the output terminal 7 is connected to the input terminal of the CPU processing unit through the industrial frequency resistor R2; The model of the power frequency chip U3 is CD4069, the input terminal 2 of the power frequency chip U3 is grounded through the power frequency capacitor C2, and the input terminal 2 of the power frequency chip U3 is connected to the output terminal 7 of the power frequency integrated circuit U2 through the power frequency resistor R7; The pulse signal is output to the input terminal 2 of the power frequency chip U3 through the output terminal 7 of the integrated circuit U2, the input terminal 6 of the power frequency chip U3 is grounded, and the input terminal 7 of the power frequency chip U3 is connected to the power supply 33V through the power frequency resistor R8; the terminal 5 of the power frequency chip U3 is grounded through the power frequency capacitor C4, and the output terminal 3 of the power frequency chip U3 is grounded through the power frequency resistor R10 and output to the CPU processing unit through the power frequency capacitor C5; The power frequency chip U3 divides the pulse signal into 12 pulse signals with equal time intervals. The pulse time interval is 1.67ms. After frequency division, the 12 pulse signals are transmitted to the CPU processing unit. Another route is to separate the high-frequency signal through the high-frequency extraction module, and the separated high-frequency current signal is conditioned, filtered and amplified by the channel conditioning module; The bandpass filter includes a high-frequency boosting transformer T1 and a high-frequency capacitor C1. The bandpass filter frequency band is 1MHz-50MHz, wherein the high-frequency boosting transformer T1 boosts the signal by 2 times; The high-frequency amplifier circuit includes a high-frequency amplifier U1, a high-frequency capacitor C2 and a high-frequency resistor R3; the positive input terminal 3 of the high-frequency amplifier U1 is grounded through the high-frequency capacitor C3, the negative input terminal 2 is grounded through the high-frequency inductor R2, and the high-frequency capacitor C2 and the high-frequency resistor R3 are connected in parallel between the output terminal 6 and the negative input terminal 2; the high-frequency amplifier circuit amplifies the high-frequency signal by 100 times; The high-frequency detection circuit includes a high-frequency resistor R5, a high-frequency resistor R6, a high-frequency diode D1 and a high-frequency capacitor C6; the output terminal 6 of the high-frequency amplifier U1 is connected through the high-frequency capacitor C5, the output terminal of the high-frequency capacitor C5 is grounded through the high-frequency resistor R5 and the high-frequency resistor R6 respectively, and the output terminal of the high-frequency capacitor C5 is output through the high-frequency diode D1; the output terminal of the high-frequency diode D1 is grounded through the high-frequency capacitor C6 and the high-frequency resistor R7 respectively; the high-frequency detection circuit reduces the frequency of the high-frequency signal to 20kHz; The follower circuit includes a high-frequency amplifier U2 and a high-frequency resistor R8; the output end of the high-frequency diode D1 is electrically connected to the positive input end 3 of the high-frequency amplifier U2; the output end 6 of the high-frequency amplifier U2 is electrically connected to the input end of the CPU processing unit through the high-frequency resistor R8; The high-frequency amplifier U2 is AD831, the high-frequency resistor R8 has a resistance value of 50 ohms, and the following circuit ensures impedance matching; the conditioned high-frequency signal is input to the CPU processing unit; The CPU processing unit synchronously collects the 12 pulse signals and the conditioned high-frequency signal and performs difference calculation. After the calculation is completed, the CPU processing unit eliminates the pulsation interference signal of the converter station and retains the partial discharge signal inside the converter transformer. The CPU processing unit transmits the interference-free partial discharge signal wirelessly to the background analysis system through the wireless communication module.

Images