CN102937691B - A kind of mine cable partial discharge monitoring and positioning intelligent device - Google Patents

Abstract

The invention is an intelligent device for on-line partial discharge monitoring and positioning of mining cables, which is mainly composed of a high-frequency current sensor, a pulse transmitting antenna, a high-frequency signal cable and a monitoring host. During on-site testing, a set of devices is placed at the cable grounding terminals of the substations in the two mining areas. The pulse transmitting antenna is connected to the monitoring host with a high-frequency signal cable, and the monitoring host controls the pulse transmitting circuit to generate a high-frequency pulse signal with variable amplitude and frequency, which is coupled to the cable under test through the pulse transmitting antenna. The high-frequency current sensor is connected to the monitoring host through a high-frequency cable. The coil detects and receives the high-frequency pulse signal in the cable. The monitoring host can immediately transmit a high-frequency pulse when it detects the high-frequency pulse signal. The amplitude of the transmitted pulse is and the same frequency as the received pulse. Through the above process, the precise time synchronization at both ends of the cable is completed, and the purpose of accurately locating the partial discharge point of the cable is achieved.

Description

An intelligent device for on-line monitoring and positioning of mine cable partial discharge

technical field

The invention relates to the on-line monitoring technology of the insulation state of mining power equipment and its application field, in particular to the related technical field of non-intrusive on-line partial discharge monitoring and positioning when evaluating the insulation state of mining cables.

Background technique

The insulation status monitoring, analysis and fault location of power cables in mines are important contents of mine power equipment detection, and also necessary monitoring means to ensure mine safety. In recent years, the urban power grid management department has achieved good results by installing high-frequency current sensors at the grounding wires of power cables for short or long periods of time to measure the pulse current flowing through the grounding wires, analyze the intensity and frequency of partial discharges, and monitor the insulation status of power cables. Practice effect. However, there are still some technical problems that have not been resolved, mainly including strong background noise interference during online monitoring, inaccurate estimation of the propagation speed of high-frequency pulses, and difficulty in determining the attenuation system during high-frequency pulse propagation, resulting in poor insulation status monitoring results. Positioning is often wrong. On the other hand, these advanced detection technologies have not been used in the safety detection of mine power equipment, and cannot improve the technical level of fault monitoring and fault location of power equipment in mines.

For the monitoring of cable insulation status and fault location in mines, the main difficulties currently faced are as follows:

First of all, the background noise interference problem: In the online monitoring environment, many external strong electromagnetic interferences will propagate to the power grid through the grounding grid, grounding copper bars, and cable grounding wires. These strong interferences are usually larger than the actual discharge signal, resulting in signal noise during detection. The ratio is very low, and the partial discharge signal is difficult to extract. At the same time, it also causes the launch device of the fault location system to be falsely triggered, which increases the difficulty of fault location and reduces the efficiency of fault location.

Secondly, it is difficult to accurately estimate the propagation speed of high-frequency pulses in the cable, which is also an important problem faced by the cable insulation state online monitoring and fault location system. In the currently implemented systems, the propagation velocity used in fault location is generally based on empirical values, and it is assumed that the propagation velocity remains constant under various circumstances. This is often inconsistent with the actual situation, resulting in large positioning errors and time-consuming and laborious troubleshooting.

Therefore, designing a safe, portable, and efficient cable insulation status monitoring and fault location device to solve the problem of on-line monitoring and location of mine cable partial discharge and ensure the safe operation of mine power equipment is a research hotspot in the current industry.

Contents of the invention

The invention provides an intelligent device for on-line partial discharge monitoring and positioning of mining cables, which has the characteristics of safety, portability, flexibility and accuracy, and can largely solve the low detection sensitivity of the current on-line monitoring of the insulation state of mining power cables and fault location systems , The efficiency of fault location is not high, etc. It has improved the technical level of related fields and made up for the shortcomings of monitoring technology in practical application.

The present invention is an intelligent device for on-line partial discharge monitoring and positioning of mining cables, which is mainly composed of a high-frequency current sensor, a pulse transmitting antenna, a high-frequency signal cable and a monitoring host. The high-frequency current sensor is connected to the monitoring host through a high-frequency signal cable. The pulse transmitting antenna is connected to the monitoring host through a high-frequency signal cable. The monitoring host includes a pulse receiving circuit, an acquisition board, a pulse transmitting circuit and an industrial computer. The monitoring and positioning intelligent device, the high-frequency current sensor and the pulse transmitting antenna are respectively socketed on the cable grounding wire of the substation in the same mining area. When the monitoring host captures the partial discharge signal, the pulse generating circuit generates the same frequency but High-frequency pulses whose amplitude is much larger than that of partial discharge are transmitted through the pulse transmitting antenna.

The pulse output circuit is mainly composed of high-speed electronic switch electronic switch K61, inductor L61, inductor L62, inductor L63, capacitor C61, capacitor C62, capacitor C63, capacitor C64, resistor R61, resistor R62, resistor R63 and operational amplifier OP61; The high-speed electronic switch K61, inductance L61, inductance L62, inductance L63, and operational amplifier are sequentially connected in series, the resistor R61 is connected to the non-inverting input of the operational amplifier, one end of the capacitor C64 is grounded, and the other end is connected to the inverting input of the operational amplifier terminal, one end of the resistor R63 is grounded, and one end is connected to the inverting input terminal of the operational amplifier, and the resistor R62 is connected between the non-inverting input terminal and the output terminal of the operational amplifier; the node between the operational amplifier and the inductor L63 passes through the resistor R64 is grounded, the node between the inductance L63 and the wringer L62 is grounded through the capacitor C63, the node between the inductance L62 and the inductance L61 is grounded through the resistor and capacitor C62, the high-speed electronic switch K61 and the inductance 61 The node between is grounded through capacitor C61.

The resistance of the pulse generation circuit adopts high-precision low-temperature drift resistors with an accuracy of one thousandth and a temperature coefficient of less than 10×10-6/°C; the capacitors adopt COG capacitors with stable capacitance, wide temperature range, and small temperature drift; The operational amplifier adopts a high-precision instrumentation operational amplifier, and its indicators should at least meet: offset voltage 5mV, open-loop gain 100dB, bias current 10pA, and effective bandwidth 100MHz.

The pulse transmitting antenna is mainly composed of an antenna shell, an Archimedes antenna, an antenna discharge tube, a differential resistor, and an antenna BNC connector. The Archimedes spiral antenna is located in the antenna shell, and the antenna excitation port is drawn from the antenna shell and connected to To the antenna BNC connector, the differential resistor and the antenna discharge tube are connected in series to both ends of the antenna BNC connector.

The coil of the Archimedes spiral antenna is drawn on a PCB board, the PCB board uses FR4 base material, the number of turns of the Archimedes spiral antenna does not exceed 10 turns, and the equivalent capacitance of the antenna does not exceed 100pF.

The high-frequency current sensor is mainly composed of a clamp-shaped sensor shell, a magnetic core, a coil, an integrating resistor, a passive bandpass filter, a sensor discharge tube, and a sensor BNC connector. The coil is wound on the magnetic core, and the magnetic The core is located in the sensor shell, one end of the coil is drawn from the sensor shell and connected to the sensor BNC connector through a passive bandpass filter, and the integrating resistor and the sensor discharge tube are connected in series to both ends of the sensor BNC connector, and The junction between the integrating resistor and the sensor discharge tube is connected to the input of the passive bandpass filter.

Described passive band-pass filter mainly is made of inductance L41, inductance L42, inductance L43, inductance L44, inductance L45, electric capacity C41, electric capacity C42, electric capacity C43, electric capacity C44, electric capacity C45, electric capacity C46, electric capacity C47 to form; The left end of L41 is grounded through capacitor C41; The right end of described inductance L41 and the left end of inductance L42 are grounded through capacitor C42; The right end of described inductance L42 and the left end of capacitor C44 are grounded through capacitor C43; The right end of described capacitor C44 and the capacitor C45 The left end is grounded through the inductor L43, the right end of the capacitor C45 and the left end of the capacitor C46 are grounded through the inductor L44, and the right end of the capacitor C46 and the left end of the capacitor C47 are grounded through the inductor L45.

The high-frequency signal cable is a single-core coaxial cable with attenuation less than 0.5dB/m within 45MHz.

The pulse transmission circuit, the acquisition board, and the pulse amplifying circuit are enclosed in the host casing, and the outer peripheries of the host casing, the sensor casing, and the antenna casing are all provided with insulating materials, and the insulating materials are all made of epoxy resin.

After adopting this design, the present invention has following advantage at least:

1. The receiving coil shell, the transmitting antenna shell and the host shell used in the present invention all have the insulation level and explosion-proof requirements required by the mine site, which ensures the safety of the user when operating the instrument;

2. When the present invention is used for on-site monitoring, operators place a device in the substations of the two mining areas respectively. Connect the high-frequency current sensor and the pulse transmitting antenna to the grounding wire of the cable at the same time, and detect partial discharge signals of different intensities by adjusting the intelligent analysis software of the monitoring host. When the partial discharge signal is captured, the monitoring host automatically recognizes the amplitude and frequency of the signal, and then sends a high-frequency pulse with the same frequency but much larger amplitude than the partial discharge through the transmitting antenna. The monitoring hosts at both ends can each receive the high-frequency pulse, so that precise time synchronization can be completed, and then the propagation speed of the high-frequency pulse in the cable can be accurately calculated. By calculating the amplitude difference between the transmitted pulse and the transmitted pulse, the attenuation coefficient when the pulse is transmitted along the cable can be accurately calculated. Since the transmitted pulse amplitude is much larger than both the background noise and the partial discharge signal, the probability of double-terminal communication failure is reduced, and the accuracy of fault location can be greatly improved. After adopting the above strategy, the efficiency of staff monitoring, the accuracy of partial discharge location and the reliability of state assessment have all been greatly improved.

Description of drawings

The above is only an overview of the solutions of the present invention. In order to more clearly illustrate the technical means of the present invention, the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a composition diagram of an intelligent device for on-line partial discharge monitoring and positioning of mining cables according to the present invention.

Fig. 2 is a schematic diagram of the basic composition of a high-frequency current sensor of an intelligent device for on-line partial discharge monitoring and positioning of mining cables according to the present invention.

Fig. 3 is a schematic diagram of the basic composition of a pulse transmitting antenna of a mine cable partial discharge on-line monitoring and positioning intelligent device according to the present invention.

Fig. 4 is a schematic diagram of the basic structure of a passive band-pass filter circuit of an on-line partial discharge monitoring and positioning intelligent device for mine cables according to the present invention.

Fig. 5 is a schematic diagram of the basic composition of a mainframe of a mining cable partial discharge on-line monitoring and positioning intelligent device.

Fig. 6 is a schematic diagram of the basic composition of a pulse emission circuit of an on-line partial discharge monitoring and positioning intelligent device for mining cables.

Fig. 7 is a schematic diagram of an on-line partial discharge monitoring and positioning intelligent device for mining cables according to the present invention being applied on site.

detailed description

As shown in Figure 1, an intelligent device for on-line partial discharge monitoring and positioning of mining cables is mainly composed of a high-frequency current sensor 11, a pulse transmitting antenna 12, a high-frequency signal cable 13, and a monitoring host 14.

As shown in FIG. 2 , the high-frequency current sensor 11 is composed of a clamp-shaped sensor shell 21 , a magnetic core 22 , a coil 23 , an integrating resistor 24 , a passive bandpass filter 25 , a sensor discharge tube 26 , and a sensor BNC connector 27 . The coil 23 is wound around the periphery of the magnetic core 22, the magnetic core 22 is arranged in the sensor housing 21, one end of the coil is drawn from the sensor housing and connected to the sensor BNC connector 27 through a passive bandpass filter 25, The integrating resistor 24 and the sensor discharge tube 26 are connected in series to both ends of the BNC connector of the sensor, and the node between the integrating resistor 24 and the sensor discharge tube 26 is connected to the input terminal of the passive bandpass filter 25 .

As shown in Figure 3, the pulse transmitting antenna 12 is mainly composed of an antenna shell 31, an Archimedes antenna 32, an antenna discharge tube 33, a differential resistor 34, and an antenna BNC connector 35. The Archimedes spiral antenna is located at the antenna Inside the shell, the Archimedes spiral antenna coil is drawn on the PCB board, the PCB board uses FR4 substrate, the number of turns of the Archimedes spiral antenna does not exceed 10 turns, and the equivalent capacitance of the antenna does not exceed 100pF. The antenna excitation port is led out from the antenna shell and connected to the antenna BNC connector, and the differential resistor and the antenna discharge tube are connected in series to both ends of the antenna BNC connector.

Figure 4 shows a passive bandpass filter 25, which is mainly composed of an inductor L41, an inductor L42, an inductor L43, an inductor L44, an inductor L45, a capacitor C41, a capacitor C42, a capacitor C43, a capacitor C44, a capacitor C45, a capacitor C46, and a capacitor C47. constitute. The inductor L41, the inductor L42, the capacitor C44, the capacitor C45, the capacitor C46, and the capacitor C47 are sequentially connected in series; one end of the capacitor C41 is grounded, and the other end is connected to the input terminal of the inductor L41; one end of the capacitor C42 is grounded, and the other end is connected to the ground. One end is connected to the node between the inductor L41 and the inductor L42; one end of the capacitor C43 is connected to the ground, and the other end is connected to the node between the inductor L42 and the capacitor C44; one end of the inductor L43 is connected to the ground, and the other end is connected to the capacitor C44 It is connected to the node between the capacitor C45; one end of the inductor L44 is connected to the ground, and the other end is connected to the node between the capacitor C45 and the capacitor C46; one end of the inductor L45 is connected to the ground, and the other end is connected to the capacitor C46 and the capacitor C47. The nodes are connected.

As shown in FIG. 5 , the monitoring host 14 is composed of a host BNC connector 51 , a pulse amplifying circuit 52 , a pulse generating circuit 53 , an acquisition board 54 , an industrial computer 55 , and a host shell 56 . The BNC connector 51 at the upper end of the monitoring host is connected to the antenna BNC connector 35 of the pulse transmitting antenna through a single-core coaxial cable, and the BNC connector at the lower end of the monitoring host is connected to the BNC connector 27 of the pulse high-frequency current sensor through a single-core coaxial cable.

The industrial computer is connected to the pulse generation circuit and the acquisition board, and the acquisition board is connected to the pulse amplification circuit. When in use, the pulse transmitting antenna and the high-frequency current sensor are installed on the cable grounding line to adjust the intelligent detection of the industrial computer. Software to detect partial discharge signals of different amplitudes. After receiving the partial discharge signal, the monitoring devices at both ends transmit pulse signals through the monitoring host respectively. By intelligently adjusting the amplitude of the transmitted pulse, the amplitude of the pulse can be greatly higher than the environmental noise during monitoring, thereby improving the accuracy of double-ended synchronization. The time difference between the arrival of the two transmitted pulses is calculated by the intelligent analysis software of the industrial computer, and finally the propagation speed of the pulse in the cable can be accurately calculated. By calculating the amplitude difference between the transmitted pulse and the transmitted pulse, the attenuation coefficient when the pulse is transmitted along the cable can be accurately calculated, so that it is possible to diagnose whether partial discharge occurs in the cable and locate the partial discharge.

The structure of the pulse generation circuit 53 is shown in Figure 6, mainly composed of high-speed electronic switch electronic switch K61, inductor L61, inductor L62, inductor L63, capacitor C61, capacitor C62, capacitor C63, capacitor C64, resistor R61, resistor R62, resistor R63 and Operational amplifier OP61 constitutes. The high-speed electronic switch electronic switch K61, inductor L61, inductor L62, and inductor L63 are sequentially connected in series, and one end of the capacitor C61 is grounded, and the other end is connected to the node between the high-speed electronic switch electronic switch K61 and the inductor L61; One end of the capacitor C62 is grounded, and the other end is connected to the node between the inductor L61 and the inductor L62; one end of the capacitor C63 is grounded, and the other end is connected to the node between the inductor L62 and the inductor L63; One end of the inductor L63 is connected to the inductor L62, the other end is connected to the output end of the operational amplifier OP61, the resistor R61 is connected to the non-inverting input end of the operational amplifier, one end of the resistor R62 is connected to the non-inverting input end of the operational amplifier, and the other end is connected to the operational amplifier The output terminal of the capacitor C64 and the resistor R63 are both connected: one end is grounded, the other end is connected to the inverting input terminal of the operational amplifier, one end of the resistor R64 is grounded, and the other end is connected to the inductance L63 and the operational amplifier. at the junction between the output terminals.

The sensor housing 21, the antenna housing 31, and the host housing 56 are all made of epoxy resin insulating material.

The main work of the analysis software included in the monitoring host can be divided into two modules. The first module can intelligently judge the amplitude and frequency of noise detected on site, and transmit high-frequency pulse signals of different amplitudes and frequencies according to the noise level on site. The second module extracts the time difference between transmitted pulses and the amplitude difference between transmitted pulses and transmitted pulses. The schematic diagram of on-site monitoring is shown in Figure 7, the cable to be tested in this figure is the cable between the cable 72 and the cable 73, which is formed by connecting multiple sections of cables through intermediate joints. A set of the device of the present invention is placed in the substation A of the mining area, and the pulse transmitting coil and the high-frequency current sensor are installed on the cable ground wire 71 at the same time. A set of the device of the present invention is also placed in the substation B of the mining area, and the pulse transmitting coil and the high-frequency current sensor are installed on the cable ground wire 74 at the same time. When the high-frequency current sensors at both ends receive the pulse, they can simultaneously transmit a high-frequency pulse signal whose amplitude and frequency have been optimized by intelligent software. The high-frequency signals emitted by both ends can be collected and analyzed by the monitoring hosts in each mining area at the same time. According to the time difference of the measured signal, the speed of the pulse propagating along the cable can be calculated, so that the fault point of the partial discharge signal can be located. At the same time, since the transmitted pulse amplitude is much larger than the background interference, the device is prevented from being frequently falsely triggered.

It can be seen that the present invention combines the high-frequency current sensor and the pulse transmitting antenna to work together at the mine detection site, and automatically judges and generates high-frequency pulse signals with variable frequency and amplitude through the monitoring host intelligent software, so that the monitoring devices at both ends receive a higher frequency than the background The pulse signal with much larger noise avoids false triggering of the devices at both ends and improves the success rate of monitoring. After precise communication between the monitoring devices at both ends of the substation in the mining area, the speed and attenuation coefficient of the high-frequency pulse signal propagating along the cable can be accurately obtained through software. After obtaining the propagation velocity and attenuation coefficient of the high-frequency pulse, the cable insulation fault degree can be accurately estimated and the fault point can be accurately located. Obviously, the device of the present invention can improve the monitoring effect and work efficiency.

The above descriptions are only preferred implementation examples of the present invention, and do not limit the present invention in any form. Those skilled in the art make some simple modifications, equivalent changes or modifications using the technical contents disclosed above, all of which fall within the scope of the present invention. within the scope of protection of the invention.

Claims (7)

1. A mining cable partial discharge online monitoring and positioning intelligent device is characterized in that: it mainly consists of a high-frequency current sensor (11), a pulse transmitting antenna (12), a high-frequency signal cable (13) and a monitoring host (14) composition, the high-frequency current sensor (11) is connected to the monitoring host (14) through a high-frequency signal cable (13), and the pulse transmitting antenna (12) is connected to the monitoring host through a high-frequency signal cable (13), and the The monitoring host computer includes a pulse amplification circuit (52), an acquisition board (54), a pulse generation circuit (53) and an industrial computer (55); two mining area substations respectively install a described on-line monitoring and positioning intelligent device, so that The high-frequency current sensor (11) and the pulse transmitting antenna (12) are respectively socketed on the cable ground wire of the substation in the same mining area. When the monitoring host (14) captures the partial discharge signal, the pulse generating circuit generates the same High-frequency pulses with a frequency but much larger amplitude than the partial discharge are emitted through the pulse transmitting antenna (12); The pulse generation circuit (53) is mainly composed of a high-speed electronic switch K61, an inductor L61, an inductor L62, an inductor L63, a capacitor C61, a capacitor C62, a capacitor C63, a capacitor C64, a resistor R61, a resistor R62, a resistor R63 and an operational amplifier OP61. The high-speed electronic switch K61, inductance L61, inductance L62, inductance L63, and operational amplifier are sequentially connected in series, the resistor R61 is connected to the non-inverting input terminal of the operational amplifier, one end of the capacitor C64 is grounded, and the other end is connected to the inverting input terminal of the operational amplifier. Input terminal, one end of the resistor R63 is grounded, one end is connected to the inverting input terminal of the operational amplifier, and the resistor R62 is connected between the non-inverting input terminal and the output terminal of the operational amplifier; the node between the operational amplifier and the inductor L63 passes through The resistor R64 is grounded, the node between the inductor L63 and the inductor L62 is grounded through the capacitor C63, the node between the inductor L62 and the inductor L61 is grounded through the capacitor C62, the high-speed electronic switch K61 and the inductor L61 The node is grounded through capacitor C61; The high-frequency current sensor (12) is mainly composed of a pincer-shaped sensor shell (21), a magnetic core (22), a coil (23), an integrating resistor (24), a passive bandpass filter (25), and a sensor discharge tube. (26), sensor BNC connector (27) is formed, and described coil is wound on magnetic core, and described magnetic core is positioned at shell, and one end of described coil is drawn from sensor shell and passes through passive band-pass filter (25 ) is connected with the sensor BNC connector (27), and the integrating resistor (24) and the sensor discharge tube (26) are connected in series at both ends of the sensor BNC connector, and the integral resistor (24) and the sensor discharge tube (26) are connected The junction is connected to the input of a passive bandpass filter (25). 2. An intelligent device for on-line partial discharge monitoring and positioning of mining cables as claimed in claim 1, characterized in that: the resistance of the pulse generating circuit is all adopted with an accuracy of one thousandth and a temperature coefficient of less than 10×10- 6/℃ high-precision low-temperature drift resistors; capacitors are COG capacitors with stable capacitance, wide temperature range, and small temperature drift; operational amplifiers are high-precision instrumentation operational amplifiers, and their indicators should at least meet: offset voltage 5mV, open-loop The gain is 100dB, the bias current is 10pA, and the effective bandwidth is 100MHz. 3. a kind of mine cable partial discharge on-line monitoring and location intelligent device according to claim 1, is characterized in that: described pulse transmission antenna (12) is mainly composed of antenna shell (31), Archimedes spiral antenna ( 32), antenna discharge tube (33), differential resistance (34), antenna BNC connector (35), the Archimedes spiral antenna is located in the antenna shell, and the antenna excitation port is drawn from the antenna shell and connected to the antenna BNC connector (35), the differential resistor (34) and the antenna discharge tube (33) are connected in series to both ends of the antenna BNC connector. 4. An intelligent device for on-line partial discharge monitoring and positioning of mining cables as claimed in claim 3, characterized in that: said Archimedes spiral antenna coil is drawn on a PCB board, and said PCB board uses FR4 substrate , the number of turns of the Archimedes spiral antenna shall not exceed 10 turns, and the equivalent capacitance of the antenna shall not exceed 100pF. 5. A mine cable partial discharge online monitoring and positioning intelligent device according to claim 1, characterized in that: said passive bandpass filter (25) is mainly composed of inductance L41, inductance L42, inductance L43, inductance L44, inductor L45, capacitor C41, capacitor C42, capacitor C43, capacitor C44, capacitor C45, capacitor C46, and capacitor C47 are formed; the left end of the inductor L41 is grounded through the capacitor C41; the right end of the inductor L41 and the left end of the inductor L42 pass through The capacitor C42 is grounded; the right end of the inductor L42 and the left end of the capacitor C44 are grounded through the capacitor C43; the right end of the capacitor C44 and the left end of the capacitor C45 are grounded through the inductor L43, and the right end of the capacitor C45 and the left end of the capacitor C46 are connected through the inductor L44 Grounded, the right end of the capacitor C46 and the left end of the capacitor C47 are grounded through the inductor L45. 6. A mine cable partial discharge online monitoring and positioning intelligent device according to any one of claims 1-5, characterized in that: said pulse generating circuit (53), pulse amplifying circuit (52) and industrial control The machine (55) is enclosed in the host casing (56), and the outer circumferences of the host casing (56), the sensor casing (21) and the antenna casing (31) are all provided with insulating materials, and the insulating materials are all made of epoxy resin. . 7. An intelligent device for on-line partial discharge monitoring and positioning of mining cables according to any one of claims 1-5, characterized in that: the high-frequency signal cable has a single-core attenuation less than 0.5dB/m within 45MHz coaxial cable.