CN115616357A - Multi-source partial discharge detection device in high-voltage switch cabinet and positioning method - Google Patents

Abstract

The invention provides a multi-source partial discharge detection device and a positioning method in a high-voltage switch cabinet, and belongs to the technical field of power detection. The method comprises the following steps: selecting a main end sensor measuring point and a slave end sensor measuring point in a switch cabinet group to be detected, and starting a detection device; the detection device carries out synchronous sampling according to the sampling frequency and the sampling depth preset by the computer terminal; extracting partial discharge pulse waveform, and obtaining X of the main end sensor _m And X of the slave end sensor _s Outputting to a computer terminal; the computer terminal carries out partial discharge source classification grouping and pulse type noise signal screening on all pulse signals of the signal group to obtain k groups of pulse signal sets Y _mk And n sets of pulse signals Y _sn (ii) a For each set Y _mk And each set Y _sn Carrying out sequential pairing analysis to generate k pairs; and obtaining a positioning distribution map of k partial discharge sources based on the k pairs.

Description

Multi-source partial discharge detection device in high-voltage switch cabinet and positioning method

Technical Field

The invention relates to the technical field of electric power detection, in particular to a multi-source partial discharge detection device and a positioning method in a high-voltage switch cabinet.

Background

The high-voltage switch is an electric power device which is used for power generation, power transmission, power distribution, electric energy conversion and consumption of an electric power system and plays roles of on-off, control or protection and the like, and mainly comprises a high-voltage circuit breaker, a high-voltage isolating switch, a grounding switch, a high-voltage load switch, a high-voltage automatic reclosing and sectioning device, a high-voltage operating mechanism, a high-voltage explosion-proof power distribution device, a high-voltage switch cabinet and the like, and plays a vital role in safe operation of a power grid and distribution and measurement of electric energy.

In view of this, monitoring and diagnosing the operation state of the high-voltage switch cabinet itself has been a subject of attention of scientific research institutions, monitoring equipment manufacturing enterprises, power production and power grid enterprises for many years, and various monitoring technologies are proposed in succession. For example, a switch cabinet with a partial discharge problem is located by collecting partial discharge signals at multiple points and then locating the switch cabinet by a traveling wave method, however, in the prior art, a single-point partial discharge position is simply located by using propagation time and propagation speed, and the situation that signals collected by a collection point may be multi-source partial discharge mixed signals is ignored, so that accurate location of a partial discharge source cannot be achieved.

Disclosure of Invention

In view of this, the present invention provides a multi-source partial discharge detection apparatus and a positioning method in a high voltage switch cabinet, which can perform accurate positioning of multiple partial discharge sources based on a multi-source partial discharge mixed signal.

The technical scheme adopted by the embodiment of the invention for solving the technical problem is as follows:

the utility model provides a multisource partial discharge detection device in high tension switchgear which characterized in that includes: the broadband sensor system comprises two broadband sensors and a host, wherein the two broadband sensors are respectively used as a main end sensor and a slave end sensor, and the host consists of a microprocessor, a high-frequency data acquisition unit, a filtering amplification unit and a power supply unit;

the broadband sensor comprises a pin electrode, an insulating laminate and a round shape which are arranged from top to bottom in sequencePlate electrode and circuit board: a through hole matched with the needle electrode in size is formed in the center of the insulating layer plate, and annular bulges are formed on the lower surface of the insulating layer plate and the edge of the through hole; the pin electrode penetrates through the through hole and is fixedly connected with the inner surface of the through hole, the head of the pin electrode is used for inducing electric field signals, and the tail end of the pin electrode is connected with the positive input end of the circuit board; a through hole is formed in the center of the plate electrode, the upper surface of the plate electrode is fixedly connected with the lower surface of the insulating layer plate, and the annular bulge of the insulating layer plate penetrates out of the through hole; the plate electrode is used for inducing an electric field signal, the plate electrode is fixedly connected with the circuit board through a hollow plate electrode connecting piece, and the plate electrode connecting piece is electrically connected with the negative input end and the grounding end of the circuit board; the pin electrode and the plate electrode connecting piece are coaxially arranged, the distance between the pin electrode and the inner wall of the plate electrode connecting piece is d, the pin electrode is used as an inner conductor, the plate electrode and the plate electrode connecting piece are jointly used as an outer conductor, the insulating laminated plate is used as an insulating medium, and the pin electrode, the plate electrode and the insulating laminated plate are combined to form a coaxial feed form; the circuit board is powered by a battery, the circuit board is provided with the positive input end, the negative input end, the grounding end and an output end, the output end of the circuit board is connected to the host through a coaxial transmission line, and an output signal U of the circuit board _out For the modulated and amplified needle electrode induction signal U _N Sensing signal U with plate electrode _P The signal difference between them;

the high-frequency data acquisition unit is used for acquiring output signals of the two broadband sensors through the acquisition card;

the filtering amplification unit is used for filtering and denoising output signals of the two broadband sensors;

the microprocessor is connected with the high-frequency data acquisition unit and the filtering amplification unit and is used for triggering the high-frequency data acquisition unit to acquire signals; receiving the signal processed by the filtering amplification unit and sending the signal to a computer terminal;

and the power supply unit is used for supplying power to the microprocessor, the high-frequency data acquisition unit and the filtering amplification unit.

Preferably, the frequency band range of the acquisition of the local discharge signal by the broadband sensor is 1-200MHz, and the output signal U of the broadband sensor _out And a local discharge signal U in the switch cabinet _sig The corresponding relation is as follows:

the above formula is obtained based on an equivalent circuit of the multi-source partial discharge detection device in the high-voltage switch cabinet, C ₁ Is the equivalent capacitance, C, between the partial discharge source and the needle electrode in the equivalent circuit ₂ Is the equivalent capacitance between the pin electrode and the plate electrode, R is the equivalent resistance of the multi-source partial discharge detection device in the high-voltage switch cabinet, s is a parameter introduced in the laplace variation, where s = j ω.

Preferably, in the broadband sensor:

the height of the annular bulge on the insulating laminated plate is not less than the thickness of the plate electrode;

the position relation between the needle electrode and the insulating layer plate is vertical to each other;

the side edge of the circuit board is fixedly connected with the lower surface of the board electrode, the pin electrode is connected with the circuit board through a solid pin electrode connecting piece with a corner, the board electrode connecting piece is coaxially arranged with the pin electrode connecting piece, and the distance between the inner wall of the board electrode connecting piece and the pin electrode connecting piece is d.

Preferably, the acquisition card is a four-channel data acquisition card with a sampling rate of 1.25GS/s and 8 sampling bits.

Preferably, the real-time main body is a detection system consisting of the multi-source partial discharge detection device in the high-voltage switch cabinet and a computer terminal, and the method comprises the following steps:

s1, in a switch cabinet group to be detected, selecting a switch cabinet positioned at the end part as a main end sensor measuring point, selecting a switch cabinet with the length being away from the main end sensor measuring point D as a slave end sensor measuring point, and starting the detection device;

s2, the detection device carries out synchronous sampling according to the sampling frequency and the sampling depth preset by the computer terminal to obtain a mixed partial discharge sampling signal group X from the main-end sensor _m’ And a mixed partial discharge sampling signal group X from the slave end sensor _s’ ；

Step S3, the detection device is used for detecting the X _m’ And said X _s’ Filtering and denoising, extracting partial discharge pulse waveforms of all signals, and obtaining a mixed partial discharge pulse signal group X of the main-end sensor _m And the mixed partial discharge pulse signal group X of the slave end sensor _s Output to the computer terminal, wherein X _m ＝{X _m1 ,X _m2 ,…X _mi }；X _s ＝{X _s1 ,X _s2 ,…X _sj }, pulse signal X _mi A pulse signal corresponding to the partial discharge signal of a certain partial discharge source acquired by the main end sensor, a pulse signal X _sj The pulse signal corresponds to a partial discharge signal of a certain partial discharge source acquired by the slave sensor;

s4, the computer terminal receives the mixed partial discharge pulse signal group X sent by the detection device _m And the mixed partial discharge pulse signal group X _s ；

Step S5, for the signal group X _m All pulse signals are subjected to partial discharge source classification grouping and pulse type noise signal screening to obtain k groups of pulse signal sets, and the k groups of pulse signal sets are recorded as Y _mk ，Y _mk ＝{Y _mk1 ,Y _mk2 ,…,Y _mkp Of the set Y _mk The elements in (1) are arranged according to the acquisition time sequence; for the signal group X _s All the pulse signals are subjected to partial discharge source classification grouping and pulse type noise signal screening to obtain n groups of pulse signal sets, and the pulse signal sets are recorded as Y _sn ，Y _sn ＝{Y _sn1 ,Y _sn2 ,…,Y _snq Of the set Y _sn The elements in (1) are arranged according to the acquisition time sequence;

step S6, for each set Y _mk And each of said sets Y _sn Performing sequential pairing analysis to make each set Y _mk Each having a corresponding one of said sets Y _sn When p = q, Y _mk And said Y _sn P elements, and the step S6 generates k pairs of pairs;

step S7, the set Y is arranged according to the arrangement sequence _mk And the set Y _sn The elements in the group I are matched in a one-to-one correspondence mode, p groups of arrival time point data are obtained by utilizing a time window and calculating a mutual correlation coefficient, and the arrival time point data comprise a time point t when a partial discharge source arrives at a measuring point of a main-end sensor _p1 And the time point t of the measuring point of the slave end sensor _p2 ；

S8, determining p positioning positions of the same partial discharge source according to the p groups of arrival time point data and the propagation velocity V of the pulse signal;

and S9, obtaining positioning distribution maps of k partial discharge sources based on the step S8 according to the k pairs obtained in the step S6.

Preferably, the step S5 is performed on the signal group X _m The steps of local discharge source classification grouping and pulse type noise signal screening of all pulse signals comprise:

step S51, calculating the signal group X in sequence _m Cross correlation coefficient a between two signals _x ；

Step S52, will satisfy a _x ≥a ₁ Classifying the two signals of the condition into the same group, and dividing the two signals into k groups to obtain k groups of pulse signal sets Y _mk Wherein a is not satisfied with any other signal _x ≥a ₁ Is identified as an impulse-type noise signal and is derived from said signal group X _m Removing;

step S53, arranging the pulse signal set Y according to the collection time sequence _mk Of (1).

Preferably, step S6 is performed for each set Y _mk And each of said sets Y _sn Step package for performing sequential pairing analysisComprises the following steps:

step S61, selecting one set Y _mk And one of said sets Y _sn Taking the first element Y of the set _mk1 And Y _sn1 Calculating the cross-correlation coefficient a between two signals _Y ；

Step S62, will satisfy a _Y ≥a ₂ The two sets of (2) are paired to obtain k sets of pairing results.

Preferably, the step S7 includes:

step S71, selecting the set Y _mk The first element Y in (1) _mk1 And the set Y _sn Element Y of corresponding position _sn1 Pairing as group 1;

step S72, finding the Y _mk1 Is recorded as t ₁₁ And selecting Y fixedly by taking the peak time as the center of the center _mk1 Length t (Y) _mk1 ) Time window Z, t (Y) of/2 _mk1 ) Is said Y _mk1 A pulse signal length;

step S73, from Y _sn1 The head end of (C) starts to select t (Y) _mk1 ) Time window Z of/2 _s Calculating the pulse signal in the time window Z and the time window Z _s Cross correlation coefficient a between internal pulse signals _Z1 Sliding the time window Z backwards _s Calculating the cross-correlation coefficient a once after each sliding _Zx To obtain a set of correlation coefficients { a } _Z1 ,a _Z12 ,…,a _Zx Selecting a time window Z corresponding to the maximum value in the correlation coefficient set _s A time difference Δ t from a time window Z, and Y _sn1 Is recorded as t ₁₂ Wherein t is ₁₂ ＝t ₁₁ +△t，t ₁₁ And t ₁₂ (ii) is group 1 point-in-time data of arrival;

step S74, the set Y is selected again _mk Second element Y in (1) _mk2 And the set Y _sn Element Y of corresponding position _sn2 And matching into a 2 nd group, calculating the 2 nd group arrival time point data, and sequentially matching until p groups of arrival time point data are calculated.

Preferably, the step S8 determines p positioning positions of the same partial discharge source according to p sets of the arrival time point data and the propagation velocity V of the pulse signal, and includes:

step S81, according to the time point t in a group of arrival time point data _p1 The time point t _p2 Calculating the distance between the partial discharge source and the measuring point of the main-end sensor according to the propagation speed V of the pulse signal;

and step S82, calculating p positioning positions of the same partial discharge source according to p groups of arrival time point data.

According to the technical scheme, the multi-source partial discharge detection device and the positioning method in the high-voltage switch cabinet provided by the embodiment of the invention comprise the following steps: s1, selecting a switch cabinet positioned at the end part from a switch cabinet group to be detected as a main end sensor measuring point, selecting a switch cabinet with the length being away from the main end sensor measuring point D as a slave end sensor measuring point, and starting a detection device; s2, the detection device carries out synchronous sampling according to the sampling frequency and the sampling depth preset by the computer terminal to obtain a mixed partial discharge sampling signal group X from the main-end sensor _m’ And a mixed partial discharge sampling signal group X from a slave sensor _s’ (ii) a Step S3, the detection device pairs X _m’ And X _s’ Filtering and denoising, extracting partial discharge pulse waveforms of all signals, and obtaining a mixed partial discharge pulse signal group X of the main-end sensor _m And a mixed partial discharge pulse signal group X of the slave end sensor _s Outputting to a computer terminal; s4, the computer terminal receives the mixed partial discharge pulse signal group X sent by the detection device _m And mixing partial discharge pulse signal group X _s (ii) a Step S5, the signal group X is paired _m All pulse signals are subjected to partial discharge source classification grouping and pulse type noise signal screening to obtain k groups of pulse signal sets, and the k groups of pulse signal sets are recorded as Y _mk ，Y _mk ＝{Y _mk1 ,Y _mk2 ,…,Y _mkp H set Y _mk The elements in (1) are arranged according to the acquisition time sequence; to signal group X _s All pulse signals are subjected to partial discharge source classification grouping and pulse type noise signal screening to obtain n groups of pulse signal sets, and the pulse signal sets are recorded as Y _sn ，Y _sn ＝{Y _sn1 ,Y _sn2 ,…,Y _snq Set Y _sn The elements in (1) are arranged according to the acquisition time sequence; step S6, for each set Y _mk And each set Y _sn Performing sequential pairing analysis to make each set Y _mk All have a corresponding set Y _sn When p = q, Y _mk And Y _sn P elements exist, and k pairs of pairs are generated in step S6; step S7, the set Y is sorted according to the order _mk And set Y _sn The elements in the group are matched in a one-to-one correspondence mode, p groups of arrival time point data are obtained by utilizing a time window and calculating a mutual correlation coefficient, and the arrival time point data comprise a time point t when a partial discharge source arrives at a main end sensor measuring point _p1 And the time point t of the measuring point of the slave end sensor _p2 (ii) a S8, determining p positioning positions of the same partial discharge source according to p groups of arrival time point data and the propagation velocity V of the pulse signal; and step S9, obtaining positioning distribution maps of k partial discharge sources based on the step S8 according to the k pairs obtained in the step S6. By the method, accurate positioning of a plurality of partial discharge sources can be realized based on the multi-source partial discharge mixed signal.

Drawings

Fig. 1 is a schematic diagram of the working principle of the multi-source partial discharge detection device in the high-voltage switch cabinet of the invention.

Fig. 2 is a structural diagram of a broadband sensor according to the present invention.

Fig. 3 is an equivalent schematic diagram of a multi-source partial discharge detection device in a high-voltage switch cabinet.

FIG. 4 is a schematic diagram of the wiring of the circuit board of the broadband sensor according to the present invention;

FIG. 5 is a comparison of the bandwidth of the sensor of the multi-source partial discharge detection device in the high voltage switch cabinet of the present invention with the TEV and HFCT.

Fig. 6 is a flow chart of a multi-source partial discharge detection method in the high-voltage switch cabinet of the invention.

Fig. 7 is a schematic diagram of the operation of the multi-source partial discharge detection device in the high-voltage switch cabinet of the invention for detecting the switch cabinet.

Fig. 8 is a diagram showing the application effect of the device of the present invention.

In the figure: the device comprises a main end sensor 1, a slave end sensor 2, a microprocessor 3, a high-frequency data acquisition unit 4, a filtering amplification unit 5, a power supply unit 6, a pin electrode 11, an insulating layer plate 12, a plate electrode 13, a circuit board 14 and a plate electrode connecting piece 15.

Detailed Description

The technical scheme and the technical effect of the invention are further elaborated in the following by combining the drawings of the invention.

The invention provides a multisource partial discharge detection device in a high-voltage switch cabinet, which can realize the detection and the initial positioning of partial discharge generated in the switch cabinet under the normal operation condition of the switch cabinet, as shown in figures 1-4, the multisource partial discharge detection device in the high-voltage switch cabinet consists of a broadband sensor and a host, wherein the broadband sensor is a high-precision and large-bandwidth partial discharge sensor assembly consisting of a needle electrode and a metal plate electrode, and each sensor is based on the principle of an electrically small antenna and completes the acquisition function of partial discharge signals by acquiring potential difference in a control electric field. In fig. 1, two broadband sensors are respectively used as a master sensor 1 and a slave sensor 2, and a host consists of a microprocessor 3, a high-frequency data acquisition unit 4, a filtering amplification unit 5 and a power supply unit 6;

as shown in fig. 2, the broadband sensor includes a pin electrode 41, an insulating layer plate 42, a circular plate electrode 43, and a circuit board 44 arranged in this order: a through hole matched with the needle electrode 41 in size is formed in the center of the insulating layer plate, and an annular bulge is formed on the lower surface of the insulating layer plate 42 and the edge of the through hole; the pin electrode 41 is arranged in the through hole in a penetrating manner and is fixedly connected with the inner surface of the through hole, the position relationship between the pin electrode and the insulating layer plate is vertical to each other, the head part of the pin electrode 41 is used for sensing electric field signals, and the tail end of the pin electrode 41 is connected with the positive input end in + of the circuit board 44; a through hole is formed in the center of the plate electrode 43, the upper surface of the plate electrode 43 is fixedly connected with the lower surface of the insulating layer plate 42, an annular bulge of the insulating layer plate 42 penetrates out of the through hole, and the height of the annular bulge on the insulating layer plate is not less than the thickness of the plate electrode; the plate electrode 43 is used for inducing electric field signals, the plate electrode 43 is fixedly connected with the circuit board 44 through a hollow plate electrode connecting piece 454, and the plate electrode connecting piece 45 is connected with the circuit board 44The negative input terminal in of the circuit board 44 is electrically connected to the ground terminal GND; the pin electrode 41 and the plate electrode connecting piece 43 are coaxially arranged, the distance between the pin electrode 41 and the inner wall of the plate electrode connecting piece is d, the pin electrode 41 serves as an inner conductor, the plate electrode 43 and the plate electrode connecting piece 45 jointly serve as an outer conductor, the insulating laminated plate 42 serves as an insulating medium, the pin electrode and the plate electrode jointly form two poles of an antenna, the two poles are isolated through the insulating laminated plate 42, the pin electrode is connected with a coaxial inner core and connected to the positive input end of the conditioning circuit, the plate electrode is connected with the negative input end of the conditioning circuit through a coaxial outer shielding layer, and the pin electrode, the plate electrode and the negative input end form a coaxial feeding form through combination of the pin electrode, the plate electrode and the plate electrode connecting piece; the circuit board 44 is powered by a lithium battery, the circuit board 44 has a positive input terminal, a negative input terminal, a ground terminal, and an output terminal out, the output terminal of the circuit board 44 is connected to a host computer through a coaxial transmission line, and an output signal U of the circuit board 44 _out For the needle electrode induction signal U after conditioning and amplification _N Sensing signal U with plate electrode _P The signal difference between them.

The pin electrode 41 may be directly connected to the circuit board 44 with the circuit board 44 and the board electrode 43 being disposed in parallel, and the board electrode connector 45 may be a cylindrical structure with the pin electrode 41 located at the center of the cylindrical structure and at a distance d from the inner wall of the cylindrical structure;

in another form, as shown in fig. 2, the side of the circuit board 44 is fixedly connected to the lower surface of the board electrode 43, the pin electrode 41 is connected to the circuit board 44 by a solid pin electrode connector 46 having a corner, and accordingly, the board electrode connector 45 has a corner structure and is arranged coaxially with the pin electrode connector 46, and the inner wall thereof is spaced from the pin electrode connector 46 by a distance d. The circuit board 44 and the lower surface of the board electrode 43 are tightly connected, so that the refraction and reflection of signals in the coaxial transmission and transmission process can be avoided, and the signal-to-noise ratio of the sensor is effectively improved.

Therefore, the broadband sensor is a broadband wireless needle plate sensor based on the electrically small antenna principle, and a conditioning amplification filter circuit is arranged in the broadband sensor to realize measurement of a local discharge signal. Because the size of the needle plate sensor is far smaller than the wavelength of the partial discharge pulse, the working principle of the needle plate sensor is equivalent to a capacitor in an electrostatic field, and capacitance values also exist between a needle electrode and a partial discharge source and between a plate electrode and the ground, the broadband sensor senses voltage jump caused when partial discharge occurs in the switch cabinet through the capacitive voltage divider principle, and then the signals are sensed.

The high-frequency data acquisition unit 4 is a four-channel data acquisition card with a sampling rate as high as 1.25GS/s and 8 sampling bits, and can be simultaneously connected with a plurality of sensors for synchronous triggering and data acquisition;

the filtering and amplifying unit 5 is a single filtering and amplifying circuit, which receives the signal of the broadband sensor and performs filtering and noise reduction on the signal, as shown in fig. 4, the single filtering and amplifying circuit is composed of an ADA4817 chip and a bridge filtering circuit, a high-pass filter composed of resistance and capacitance can adjust the bandwidth of the sensor, so that the fluctuation of the sensor between 1 MHz and 200MHz is not more than 6dB, the amplifying circuit is an in-phase proportional amplifying circuit composed of ADA4817-1, the signal gain is G =10, the working principle of the broadband sensor in the electrostatic field in the present invention is equivalent to a capacitor, for a capacitive sensor, the capacitance of the sensor is usually very small, and in actual use, the influence of stray capacitance exists. This causes changes in the ambient environment to cause changes in the stray capacitance, which affects the sensitivity of the sensor and interferes with its bandwidth. For capacitive sensors, therefore, a bridge method is generally used as a conditioning filter circuit. Fig. 4 shows the wide-band sensor with its feed output connected to a resistance-capacitance bridge and isolated by an operational amplifier. In this case, the sensor can operate in equilibrium, remain stationary in the frequency band of 1-200MHz, and achieve a 10-fold gain.

The microprocessor 3 is connected with the high-frequency data acquisition unit 4 and the filtering amplification unit 5 and is used for triggering the high-frequency data acquisition unit 4 to acquire signals; and receiving the signals processed by the filtering and amplifying unit 5 and sending the signals to a computer terminal. The microprocessor 3 is a central control processor with an FPGA as a core and is responsible for controlling the functions of triggering, collecting, communicating and the like of the whole system. When a user sends an instruction to the microprocessor through the computer, the processor triggers each channel of the acquisition card in a short time to realize synchronous acquisition of signals, and the acquired signals are filtered and amplified through the conditioning circuit. And then extracting pulse signals in the data, and recording the arrival time of each pulse signal acquired by each channel one by taking a trigger event of the acquisition card as a time zero point. The microprocessor 3 can be used for controlling the output of the power supply unit 6, ensuring that the output current is sufficient and reducing voltage ripples; a USB Hub interface is provided, so that the communication between a computer and a control unit can be realized, and the data transmission with a collection card can be completed; and providing a trigger signal, and sending the signal to the data acquisition card through the coaxial transmission line to realize the triggering of the acquisition card.

The power supply unit 6 is composed of a lithium battery and a voltage stabilizing circuit and is used for supplying power to the whole instrument. The voltage stabilizing circuit is firstly reduced by the LTM8045, and the voltage stabilizing output is realized through the LDO. The ripple level of the output voltage of the power supply is greatly reduced while the output power is ensured, so that the system noise is reduced, and the detection sensitivity is improved. Specifically, the lithium ion battery pack may be a 21V lithium ion battery pack.

As shown in fig. 3, which is an equivalent circuit diagram of the multi-source partial discharge detection device in the high-voltage switch cabinet during operation, the size of the broadband sensor is much smaller than the wavelength of the electromagnetic wave of the partial discharge signal, so that the surrounding environment can be regarded as an electrostatic field. Wherein C1 is the equivalent capacitance between the partial discharge source and the pin electrode, C2 is the equivalent capacitance between the sensor pin plate electrodes, R is the equivalent resistance of the multi-source partial discharge detection device in the high-voltage switch cabinet, s is a parameter introduced in the laplace change, where s = j ω. Output signal U of wide-band sensor _out The transfer function of the partial discharge signal U in the switch cabinet is shown as formula 1:

referring to fig. 5, the amplitude/frequency/phase/frequency characteristic curves of the multi-source partial discharge detector and the conventional HFCT and TEV sensors in the high-voltage switch cabinet according to the present invention are shown. It can be seen that the broadband sensor of the present invention can significantly increase the detection bandwidth compared to HFCT, and the non-contact sensing method is convenient in practical use. The broadband sensor and the TEV sensor belong to capacitive sensors, the working principle is approximately equivalent, but the sensitivity is greatly improved.

In the invention, the high-frequency data acquisition unit 4 can be simultaneously connected with a plurality of sensors for synchronous triggering and data acquisition, and simultaneously connected with a plurality of slave-end sensors for signal acquisition, thereby being beneficial to improving the positioning precision of partial discharge.

Further, as shown in fig. 6, the present invention also provides a multi-source partial discharge detection method in a high-voltage switch cabinet, the implementation main body includes the multi-source partial discharge detection device and the computer terminal in the high-voltage switch cabinet shown in fig. 1-4, the steps include:

s1, selecting a switch cabinet positioned at the end part from a switch cabinet group to be detected as a main end sensor measuring point, selecting a switch cabinet with the length being away from the main end sensor measuring point D as a slave end sensor measuring point, and starting a detection device;

s2, the detection device carries out synchronous sampling according to the sampling frequency and the sampling depth preset by the computer terminal to obtain a mixed partial discharge sampling signal group X from the main-end sensor 1 _m’ And a mixed partial discharge sampling signal group X from the slave sensor 2 _s’ ；

Step S3, the detection device pairs X _m’ And X _s’ Filtering and denoising, extracting partial discharge pulse waveforms of all signals, and obtaining a mixed partial discharge pulse signal group X of the main-end sensor _m And a mixed partial discharge pulse signal group X of the slave end sensor _s Output to a computer terminal, wherein X _m ＝{X _m1 ,X _m2 ,…X _mi }；X _s ＝{X _s1 ,X _s2 ,…X _sj }, pulse signal X _mi A pulse signal X corresponding to the partial discharge signal of a partial discharge source collected by the main sensor _sj The pulse signal is a pulse signal corresponding to a partial discharge signal of a certain partial discharge source acquired from the end sensor;

s4, the computer terminal receives the mixed partial discharge pulse signal group X sent by the detection device _m And mixing partial discharge pulse signal group X _s ；

Step S5, the signal group X is paired _m All pulse signals are subjected to partial discharge source classification grouping and pulse type noise signal screening to obtain k groups of pulse signal sets, and the k groups of pulse signal sets are recorded as Y _mk ，Y _mk ＝{Y _mk1 ,Y _mk2 ,…,Y _mkp Set Y _mk The elements in (1) are arranged according to the acquisition time sequence; to signal group X _s All the pulse signals are subjected to partial discharge source classification grouping and pulse type noise signal screening to obtain n groups of pulse signal sets, and the pulse signal sets are recorded as Y _sn ，Y _sn ＝{Y _sn1 ,Y _sn2 ,…,Y _snq Set Y _sn The elements in the method are arranged according to the acquisition time sequence, wherein the actual group number n is the same as the group number k, and both represent the total number of the current partial discharge sources;

step S6, for each set Y _mk And each set Y _sn Performing sequential pairing analysis to make each set Y _mk All have a corresponding set Y _sn When p = q, Y _mk And Y _sn P elements exist, and k pairs of pairs are generated in step S6;

step S7, the set Y is sorted according to the order _mk And set Y _sn The elements in the group are matched in a one-to-one correspondence mode, p groups of arrival time point data are obtained by utilizing a time window and calculating a mutual correlation coefficient, and the arrival time point data comprise a time point t when a partial discharge source arrives at a main end sensor measuring point _p1 And the time point t of the measuring point of the slave end sensor _p2 ；

S8, determining p positioning positions of the same partial discharge source according to p groups of arrival time point data and the propagation velocity V of the pulse signal;

and S9, obtaining positioning distribution maps of k partial discharge sources based on the step S8 according to the k pairs obtained in the step S6.

Wherein, step S5 is to signal group X _m The specific implementation steps of local discharge source classification grouping and pulse type noise signal screening of all pulse signals comprise:

step S51, calculating signal group X in sequence _m Cross correlation coefficient a between two signals _x ；

Step S52, will satisfy a _x ≥a ₁ Classifying the two signals of the condition into the same group, and dividing the two signals into k groups to obtain k groups of pulse signal sets Y _mk Wherein a is not satisfied with any other signal _x ≥a ₁ Is identified as an impulse-type noise signal and is derived from the signal group X _m Removing;

step S53, arranging the pulse signal set Y according to the collection time sequence _mk Of (1).

Wherein, step S6 is to each set Y _mk And each set Y _sn The specific implementation steps for carrying out the sequential pairing analysis comprise:

step S61, selecting a set Y _mk And a set Y _sn Taking the first element Y of the set _mk1 And Y _sn1 Calculating the cross-correlation coefficient a between two signals _Y ；

Step S62, a will be satisfied _Y ≥a ₂ The two sets of (2) are paired to obtain k sets of pairing results.

The specific operation of positioning the partial discharge source in the step S7 is as follows:

step S71, selecting a set Y _mk First element Y in (1) _mk1 And set Y _sn Element Y of corresponding position _sn1 Pairing as group 1;

step S72, find Y _mk1 Is recorded as t ₁₁ Taking the peak time as the center of the center to select Y _mk1 Length t (Y) _mk1 ) Time window Z, t (Y) of/2 _mk1 ) Is Y _mk1 A pulse signal length;

step S73, from said Y _sn1 The head end of (A) starts to select t (Y) _mk1 ) Time window Z of/2 _s Calculating the pulse signal in the time window Z and the time window Z _s Cross correlation coefficient a between internal pulse signals _Z1 Sliding said time window Z backwards _s Calculating the cross correlation coefficient a once after each sliding _Zx To obtain a set of correlation coefficients { a } _Z1 ,a _Z12 ,…,a _Zx Selecting the time window Z corresponding to the maximum value in the correlation coefficient set _s A time difference at from said time window Z, and said Y is _sn1 Is recorded as t ₁₂ Wherein t is ₁₂ ＝t ₁₁ T, said t ₁₁ And said t ₁₂ For group 1 arrival time point data;

step S74, selecting the set Y _mk Second element Y in (1) _mk2 And set Y _sn Element Y of corresponding position _sn2 And matching into a 2 nd group, calculating the 2 nd group arrival time point data, and sequentially matching until p groups of arrival time point data are calculated.

Step S8, determining p positioning positions of the same partial discharge source according to the p groups of arrival time point data and the propagation velocity V of the pulse signal, includes:

step S81, according to the time point t in a group of arrival time point data _p1 Time point t _p2 Calculating the distance between the partial discharge source and a main end sensor measuring point according to the propagation velocity V of the pulse signal;

and step S82, calculating p positioning positions of the same partial discharge source according to the p groups of arrival time point data.

When the microprocessor does not receive a trigger acquisition command, a synchronous trigger receiving mode is always kept, when a computer issues a synchronous trigger command to the processor, the processor configures the trigger mode, the sampling rate, the acquisition depth and the like of the acquisition card, and injects a synchronous pulse trigger signal into an external trigger channel of the A/D conversion acquisition card after 1s of delay, after the external trigger channel of the acquisition card receives the synchronous pulse, the synchronous pulse triggers detection data of the A/D conversion acquisition card high-precision wireless sensor through a pulse conditioning circuit and transmits the detection data to the microprocessor, the microprocessor firstly reduces the noise of the acquired signal through a noise reduction algorithm, extracts corresponding partial discharge pulse waveforms and records the arrival time of each waveform. The processor sends the extracted pulse data to the computer through the USB, and the pulse data is analyzed by the computer.

As shown in fig. 7, which is a field embodiment of the present invention, the wideband sensor of the present invention is installed on the outer surface of two ends of a row of multi-surface high-voltage switch cabinets, so as to effectively detect the partial discharge signal generated by the high-voltage switch cabinets, and the main machine can be placed near the switch cabinet, and the two wideband sensors are connected to the two detection channels of the main detection machine through coaxial transmission lines. When the microprocessor receives the synchronous acquisition signals, the A/D acquisition card starts to acquire partial discharge signals sensed by the two sensors at a high speed, and uploads the extracted partial discharge pulse data to the computer, so that the positions of a plurality of internal partial discharge sources can be found quickly while the detection of the partial discharge signals of the multi-surface switch cabinet can be effectively realized. For the staff, the switch cabinet with partial discharge can be judged through the detected positioning spectrogram displayed on the computer, so that defect elimination work in the switch cabinet is realized, and pattern recognition of partial discharge can be roughly realized through the detected phase spectrogram (PRPD).

As shown in fig. 8, which is a schematic diagram of the working effect of the multi-source partial discharge detection and positioning device used in the switch cabinet, the high-precision wireless sensors disposed on both sides of the switch cabinet collect the time domain waveform diagrams of the partial discharge signals after conditioning and amplification in a plurality of power frequency cycles, as shown in the upper two diagrams in fig. 7. It can be seen from the figure that the collected signal mainly comprises three parts of partial discharge pulse signals, white noise signals and pulse type noise signals in various forms. After the sensor finishes signal acquisition, the system can firstly carry out noise reduction on the acquired signal through a corresponding filtering noise reduction algorithm, so that white noise in the system and the surrounding environment is removed. Compared with the traditional single-ended detection, the pulse noise has the characteristics of waveform, amplitude and phase difference with the characteristics of typical partial discharge, the traditional partial discharge detection technology can misjudge the noise into partial discharge, and the partial discharge detection of the switch cabinet is not reliable enough in a complex electromagnetic environment. Under the detection environment of the invention, the signals received by the sensors at the left end and the right end can continuously and repeatedly extract pulses and obtain the cross correlation coefficient among a plurality of pulses, but the cross correlation between the pulse type noise and other pulse signals is extremely low, so that the noise can be eliminated by the method, and only partial discharge pulse signals are reserved. In addition, for the partial discharge sources, due to different types of defects and differences in circuit topology, pulse waveforms generated when partial discharge occurs are different for different partial discharge sources. Therefore, a plurality of partial discharge pulses generated by the same partial discharge source have great correlation, and the partial discharge pulses between different partial discharge sources have small correlation. The separation of the multi-source partial discharges can also be realized by classifying the partial discharges by looking at the cross correlation among the pulse waveforms. When the arrival time of the signal is determined, the positioning accuracy of the partial discharge can be greatly improved by solving the cross-correlation coefficient and finding the maximum value point of the cross-correlation coefficient as the arrival time of the signal. As can be seen from the positioning spectrogram, a plurality of positioning identifiers exist for the same partial discharge source, and 3 clusters of positioning results gathered at different positions successfully separate and position the multi-source partial discharge. For signals generated by the same partial discharge source, the partial discharge detection method can also be used for independently extracting the signals, checking waveform information and a PRPD spectrogram, and accordingly helping pattern recognition of partial discharge and the like.

The invention adopts a cross-correlation algorithm to process the local amplification signal. If a plurality of partial discharge sources exist in the switch cabinet, for partial discharge signals collected by the same sensor, partial discharge signals generated by each partial discharge source are included at the same time, and a plurality of partial discharge signals generated by each partial discharge source are also included, firstly, pulse signals are extracted in an array mode through the rising edge and the falling edge of the pulse signals, and correlation among all pulses is obtained. In addition, for the same partial discharge generated by the same partial discharge source, the sensors at two ends of the switch cabinet can acquire very similar pulse waveforms, the cross correlation coefficients of the two waveforms are obtained by establishing a time window with the same length as the pulse waveforms and continuously sliding the window, the time point with the maximum cross correlation coefficient is found and used as the arrival time of the partial discharge signal, and then the position is calculated according to the time difference. The method effectively reduces the influence of waveform distortion caused by high-frequency attenuation and dispersion effect, avoids errors in positioning when a plurality of partial discharge sources exist in the switch cabinet, and greatly improves the positioning accuracy of partial discharge.

The multisource partial discharge detection device in the high-voltage switch cabinet provided by the invention realizes the detection and the primary positioning of partial discharge generated in the switch cabinet under the normal operation condition, wherein the adopted broadband sensor has the characteristics of broadband and high sensitivity, can synchronously acquire partial discharge signals within the range of 1-200HMz, and compared with the traditional UHF or TEV, the sensor can realize the high-precision and large-bandwidth detection of partial discharge under the non-contact condition; for the condition that a plurality of partial discharge sources exist in the switch cabinet, partial discharge pulses are classified and the arrival time of signals is determined by obtaining the correlation coefficient between pulse waveforms, so that the separation of multi-source partial discharge can be realized, the partial discharge positioning precision can be greatly improved, and the problem of difficulty in positioning partial discharge when a plurality of discharge sources exist in the conventional switch cabinet is solved. The multisource partial discharge detection device in the high-voltage switch cabinet is simple to operate, convenient to use, high in reliability and easy to carry, and provides convenience for daily routing inspection of partial discharge in the switch cabinet.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (9)

1. The utility model provides a multisource partial discharge detection device in high tension switchgear which characterized in that includes: the broadband sensor system comprises two broadband sensors and a host, wherein the two broadband sensors are respectively used as a main end sensor and a slave end sensor, and the host consists of a microprocessor, a high-frequency data acquisition unit, a filtering amplification unit and a power supply unit;

the broadband sensor comprises a pin electrode, an insulating laminate, a circular plate electrode and a circuit board which are arranged from top to bottom in sequence: the center of the insulating laminate is provided with a hole matched with the size of the needle electrodeThe through hole is positioned on the lower surface of the insulating layer plate, and an annular bulge is arranged on the edge of the through hole; the pin electrode is arranged in the through hole in a penetrating manner and is fixedly connected with the inner surface of the through hole, the head of the pin electrode is used for inducing electric field signals, and the tail end of the pin electrode is connected with the positive input end of the circuit board; a through hole is formed in the center of the plate electrode, the upper surface of the plate electrode is fixedly connected with the lower surface of the insulating layer plate, and the annular bulge of the insulating layer plate penetrates out of the through hole; the plate electrode is used for inducing electric field signals, the plate electrode is fixedly connected with the circuit board through a hollow plate electrode connecting piece, and the plate electrode connecting piece is electrically connected with the negative input end and the grounding end of the circuit board; the pin electrode and the plate electrode connecting piece are coaxially arranged, the distance between the pin electrode and the inner wall of the plate electrode connecting piece is d, the pin electrode is used as an inner conductor, the plate electrode and the plate electrode connecting piece are jointly used as an outer conductor, the insulating laminated plate is used as an insulating medium, and the pin electrode, the plate electrode and the plate electrode connecting piece are combined to form a coaxial feed form; the circuit board is powered by a battery, the circuit board is provided with the positive input end, the negative input end, the grounding end and an output end, the output end of the circuit board is connected to the host through a coaxial transmission line, and an output signal U of the circuit board _out For the modulated and amplified needle electrode induction signal U _N Sensing signal U with plate electrode _P The signal difference between them;

the high-frequency data acquisition unit is used for acquiring output signals of the two broadband sensors through the acquisition card;

the filtering amplification unit is used for filtering and denoising output signals of the two broadband sensors;

the microprocessor is connected with the high-frequency data acquisition unit and the filtering amplification unit and is used for triggering the high-frequency data acquisition unit to acquire signals; receiving the signal processed by the filtering amplification unit and sending the signal to a computer terminal;

and the power supply unit is used for supplying power to the microprocessor, the high-frequency data acquisition unit and the filtering amplification unit.

2. The multi-source partial discharge detection device in a high voltage switch cabinet according to claim 1, wherein the collection frequency band of the broadband sensor for the partial discharge signal is 1-200MHz, and the output signal U of the broadband sensor _out And a local discharge signal U in the switch cabinet _sig The corresponding relation is as follows:

the above formula is obtained based on an equivalent circuit of the multi-source partial discharge detection device in the high-voltage switch cabinet, C ₁ Is the equivalent capacitance, C, between the partial discharge source and the needle electrode in the equivalent circuit ₂ Is the equivalent capacitance between the pin electrode and the plate electrode, R is the equivalent resistance of the multi-source partial discharge detection device in the high-voltage switch cabinet, s is a parameter introduced in the laplace variation, where s = j ω.

3. The multi-source partial discharge detection device in a high-voltage switch cabinet according to claim 2, wherein in the broadband sensor:

the height of the annular bulge on the insulating laminate is not less than the thickness of the plate electrode;

the position relationship between the needle electrode and the insulating layer plate is vertical to each other;

the side edge of the circuit board is fixedly connected with the lower surface of the board electrode, the pin electrode is connected with the circuit board through a solid pin electrode connecting piece with a corner, the board electrode connecting piece is coaxially arranged with the pin electrode connecting piece, and the distance between the inner wall of the board electrode connecting piece and the pin electrode connecting piece is d.

4. The device for detecting the multi-source partial discharge in the high-voltage switch cabinet according to claim 3, wherein the acquisition card is a four-channel data acquisition card with a sampling rate of 1.25GS/s and a sampling bit number of 8 bits.

5. A multisource partial discharge positioning method in a high-voltage switch cabinet is characterized in that a real-time main body is a detection system consisting of a multisource partial discharge detection device in the high-voltage switch cabinet and a computer terminal, and the method comprises the following steps:

step S1, in a switch cabinet group to be detected, selecting a switch cabinet positioned at the end part as a main end sensor measuring point, selecting a switch cabinet with a length being away from the main end sensor measuring point D as a slave end sensor measuring point, and starting the detection device;

s2, the detection device carries out synchronous sampling according to the sampling frequency and the sampling depth preset by the computer terminal to obtain a mixed partial discharge sampling signal group X from the main-end sensor _m’ And a mixed partial discharge sampling signal group X from the slave end sensor _s’ ；

Step S3, the detection device is used for detecting the X _m’ And said X _s’ Filtering and denoising, extracting partial discharge pulse waveforms of all signals, and obtaining a mixed partial discharge pulse signal group X of the main-end sensor _m And the mixed partial discharge pulse signal group X of the slave end sensor _s Output to the computer terminal, wherein X _m ＝{X _m1 ,X _m2 ,…X _mi }；X _s ＝{X _s1 ,X _s2 ,…X _sj }, pulse signal X _mi A pulse signal corresponding to the partial discharge signal of a certain partial discharge source acquired by the main end sensor, a pulse signal X _sj A pulse signal corresponding to a partial discharge signal of a certain partial discharge source acquired by the slave end sensor;

s4, the computer terminal receives the mixed partial discharge pulse signal group X sent by the detection device _m And the mixed partial discharge pulse signal group X _s ；

Step S5, for the signal group X _m All pulse signals are subjected to partial discharge source classification grouping and pulse type noise signal screening to obtain k groups of pulse signal sets, and the k groups of pulse signal sets are recorded as Y _mk ，Y _mk ＝{Y _mk1 ,Y _mk2 ,…,Y _mkp Of the set Y _mk The elements in (1) are arranged according to the acquisition time sequence; for the signal group X _s All the pulse signals are subjected to partial discharge source classification grouping and pulse type noise signal screening to obtain n groups of pulse signal sets, and the pulse signal sets are recorded as Y _sn ，Y _sn ＝{Y _sn1 ,Y _sn2 ,…,Y _snq Of the set Y _sn The elements in (1) are arranged according to the acquisition time sequence;

step S6, for each set Y _mk And each of said sets Y _sn Performing sequential pairing analysis to make each set Y _mk Each having a corresponding one of said sets Y _sn When p = q, Y _mk And said Y _sn P elements, and the step S6 generates k pairs of pairs;

step S7, the set Y is arranged according to the arrangement sequence _mk And the set Y _sn The elements in the group are paired in a one-to-one correspondence manner, and p groups of arrival time point data are obtained by utilizing a time window and calculating a mutual correlation coefficient, wherein the arrival time point data comprise a time point t when a partial discharge source arrives at a main end sensor measuring point _p1 And the time point t of the measuring point of the slave end sensor _p2 ；

S8, determining p positioning positions of the same partial discharge source according to the p groups of arrival time point data and the propagation velocity V of the pulse signal;

and S9, obtaining positioning distribution maps of k partial discharge sources based on the step S8 according to the k pairs obtained in the step S6.

6. The method for locating the multi-source partial discharge in the high-voltage switch cabinet according to claim 5, wherein the step S5 is to locate the signal group X _m The steps of local discharge source classification grouping and pulse type noise signal screening of all pulse signals comprise:

step S51, calculating the signal group X in sequence _m Cross correlation coefficient a between two signals _x ；

Step S52, will satisfy a _x ≥a ₁ Classifying the two signals of the condition into the same group, and dividing the two signals into k groups to obtain k groups of pulse signal sets Y _mk Wherein a is not satisfied with any other signal _x ≥a ₁ Is identified as an impulse-type noise signal and is derived from said signal group X _m Removing;

step S53, arranging the pulse signal set Y according to the collection time sequence _mk Of (1).

7. The method for locating multi-source partial discharge in high-voltage switch cabinet according to claim 6, wherein the step S6 is performed for each set Y _mk And each of said sets Y _sn The steps of performing sequential pairing analysis include:

step S61, selecting one set Y _mk And one of said sets Y _sn Taking the first element Y of the set _mk1 And Y _sn1 Calculating the cross-correlation coefficient a between two signals _Y ；

Step S62, a will be satisfied _Y ≥a ₂ The two sets of (2) are paired to obtain k sets of pairing results.

8. The method for locating the multi-source partial discharge in the high-voltage switch cabinet according to claim 7, wherein the step S7 comprises:

step S71, selecting the set Y _mk The first element Y in (1) _mk1 And the set Y _sn Element Y of corresponding position _sn1 Pairing as group 1;

step S72, finding the Y _mk1 Is recorded as t ₁₁ And selecting Y fixedly by taking the peak time as the center of the center _mk1 Length t (Y) _mk1 ) Time window Z, t (Y) of/2 _mk1 ) Is the said Y _mk1 A pulse signal length;

step S73, from said Y _sn1 The head end of (A) starts to select t (Y) _mk1 ) Time window Z of/2 _s Calculating the pulse signal in the time window Z and the time window Z _s Cross correlation coefficient a between internal pulse signals _Z1 Sliding the time window backwardsZ _s Calculating the cross correlation coefficient a once after each sliding _Zx To obtain a set of correlation coefficient set { a } _Z1 ,a _Z12 ,…,a _Zx Selecting the time window Z corresponding to the maximum value in the correlation coefficient set _s A time difference at from said time window Z, and said Y is _sn1 Is recorded as t ₁₂ Wherein t is ₁₂ ＝t ₁₁ T, said t ₁₁ And said t ₁₂ For group 1 arrival time point data;

step S74, the set Y is selected again _mk Second element Y in (1) _mk2 And the set Y _sn Element Y of corresponding position _sn2 And matching into a 2 nd group, calculating the 2 nd group arrival time point data, and sequentially matching until p groups of arrival time point data are calculated.

9. The method for positioning the multi-source partial discharge in the high-voltage switch cabinet according to claim 7, wherein the step S8 of determining p positioning positions of the same partial discharge source according to p sets of the arrival time point data and the propagation velocity V of the pulse signal comprises:

step S81, according to the time point t in a group of arrival time point data _p1 The time point t _p2 Calculating the distance between the partial discharge source and the measuring point of the main-end sensor according to the propagation speed V of the pulse signal;

and step S82, calculating p positioning positions of the same partial discharge source according to p groups of arrival time point data.

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