Mining cable multi-source information sensing system and cable insulation diagnosis method

Abstract

The invention discloses a mining cable multi-source information sensing system and a cable insulation diagnosis method, and belongs to the technical field of cable monitoring. The system comprises a sensing module, a transmission module and a main control module, the sensing module comprises a signal GPS unit, a signal acquisition unit and a signal processing unit; a time service signal of the GPS unit is transmitted to the main control module through the transmission module and communicates with a satellite for time service calibration; the signal acquisition unit acquires a multi-source information signal of cable operation and transmits the acquired signal to the signal processing unit; the signal processing unit preprocesses the collected signals, then the signals are transmitted to the cloud control center of the main control module through the transmission module, and the preprocessed signals are analyzed and calculated in the cloud control center, so that the operation situation of the mining cable is judged and predicted. The system only needs to measure voltage and current at the head end and the tail end of the cable, cable parameters can be obtained, and then the insulation state of the cable is judged.

Description

Technical Field

[0001] The present invention relates to the technical field of cable monitoring, and in particular to a multi-source information sensing system for mining cables and a cable insulation diagnosis method. Background Art

[0002] The coal mine power grid is a special, independent, and huge terminal power system connected to the large power grid. It has higher requirements for the safety and reliability of power supply. As an important component of the coal mine power grid and the core component of the coal mine power supply system, the operating safety status of coal mine cables directly affects the stable operation of the coal mine power grid and even affects the production safety of coal mines.

[0003] The operating safety status of coal mine cables is mainly affected by their operating environment and operating working status. Different from the operating working environment of cables in ordinary power grids, the air humidity in coal mines is high, and the temperature difference between different areas is large. The insulation of mine cables is very easy to age, resulting in insulation degradation. In addition, the space in coal mines is narrow, and mine cables are easily damaged by sudden situations such as smashing, bumping and dragging, resulting in grounding or leakage faults. Coal mine power grids usually adopt the neutral point grounding method through arc suppression coils. Although this grounding method can allow the power supply system to operate with faults for 2-3 hours in principle, the underground environment of coal mines is different from that on the ground. The closed environment underground is filled with a large amount of gas and coal dust. When the mine cable discharges or single-phase grounding occurs due to insulation failure, the generated electric sparks can easily cause the environment to reach "fire" and "detonation" conditions, causing coal mine electromechanical accidents, cable "blasting", underground fires, explosions and other serious coal mine safety accidents. Among these, coal mine cable failure is the direct cause of cable blasting accidents, an important factor leading to some electromechanical accidents, and the main external fire source causing gas accidents.

[0004] In terms of monitoring and diagnosis of cable faults, domestic and foreign research has proposed a variety of traditional methods, such as AC injection method, DC injection method, DC component method, zero-sequence current method and dielectric loss method. However, these methods have certain defects when applied underground in coal mines. For this reason, many scholars have also proposed other mining cable monitoring and diagnosis methods in recent years. For example, Professor Song Guobing and others from Xi'an Jiaotong University used traveling waves to diagnose the occurrence and location of cable faults; Dr. Lu Dan and others from China University of Mining and Technology used pattern recognition to obtain insulation resistance values ​​and judge coal mine cable faults; in addition, Dr. Liu Jiaxin and others from Liaoning Electric Power Research Institute proposed to diagnose cable status through optical fiber temperature measurement. In terms of operation status evaluation, prediction and abnormal warning, Professor Luo Qingyue and others from Shaoyang University proposed a multi-index comprehensive static voltage stability weak bus identification method; Dr. Vivien Li from China Electric Power Research Institute proposed a cable aging status evaluation method based on operation data analysis.

[0005] However, the current methods still have the following problems and difficulties:

[0006] (1) Cable status monitoring is not comprehensive, and there are many factors that affect the safety of cable operation. Due to the harsh underground environment of coal mines, poor communication, limited sensor technology and other reasons, the current methods are mainly based on local cable insulation monitoring and diagnosis. Moreover, the type of monitoring data is single, and the current methods are mostly based on monitoring the zero-sequence current and zero-sequence voltage of the cable line to determine the cable fault. However, environmental factors such as ambient temperature, humidity, dust, and gas content during the operation of coal mine cables may affect the safe operation of cables, and electrical quantity factors such as current, voltage, harmonics, and frequency during the operation of coal mine cables will also affect the operation of cables. Due to the small number of underground monitoring nodes in coal mines and the small type and amount of monitoring data, it is impossible to globally monitor the faults and status of cables in the entire coal mine power grid.

[0007] (2) Inaccurate cable fault diagnosis. In recent years, most of the new diagnostic methods proposed are based on the algorithms for diagnosing the status of ordinary power grid cables. The proposed algorithms are mainly based on traditional expert system algorithms or reliability theories. Although these methods have certain applicability, there is a lack of cable status diagnosis methods specifically for the special and extreme environment of coal mines. Most of these algorithms compare the variable residuals of the state with the set threshold to identify cable faults. Affected by the interference of the environment and underground load, the noise of the monitored fault signal is relatively large, resulting in large errors in the calculated diagnostic results. In particular, for early fault diagnosis based on partial discharge signal monitoring, the fault signal is often covered by noise, resulting in inaccurate judgments by the diagnostic algorithm.

[0008] (3) Cable fault warning is not timely. Due to the grounding method of the coal mine power grid, the fault current when the cable fails is small and the characteristics are not obvious. In current research, the occurrence of a fault can only be diagnosed when the insulation resistance value is low or it evolves into a more obvious grounding fault.

[0009] Therefore, it is necessary to propose a multi-source information perception system for mining cables and a cable insulation diagnosis method to solve the above-mentioned technical problems existing in the prior art. Summary of the invention

[0010] The object of the present invention is to provide a multi-source information perception system for mining cables and a cable insulation diagnosis method, so as to diagnose the operating status of mining cables and monitor faults before the mining cables fail.

[0011] To achieve the above object, the present invention provides the following technical solutions:

[0012] A multi-source information perception system for mining cables, comprising a perception module for cable operation situation perception and extraction, a transmission module, and a main control module for cable operation situation assessment and situation prediction;

[0013] The perception module includes a signal GPS unit, a signal acquisition unit, and a signal processing unit;

[0014] The timing signal of the GPS unit is transmitted to the main control module through the transmission module, and the main control module communicates with the satellite for timing calibration;

[0015] The signal acquisition unit acquires multi-source information signals of the cable operation, wherein the multi-source information signals include voltages and currents at both ends of each line cable, and then transmits the acquired signals to the signal processing unit;

[0016] The signal processing unit pre-processes the collected signals, and then transmits the pre-processed signals to the cloud control center of the main control module through the transmission module, and analyzes and calculates the pre-processed signals in the cloud control center to judge and predict the operating status of the mining cable.

[0017] Preferably, the signal acquisition unit collects multi-source information signals in sections according to the connection points of the cables and the distribution of lanes.

[0018] Preferably, the signal acquisition unit acquires multi-source information signals of the cable operation through a multi-source sensor.

[0019] Preferably, the multi-source information signal also includes a temperature signal, a humidity signal, a dust content signal, a gas content signal, and a harmonic signal and a frequency signal during cable operation.

[0020] Preferably, according to the location of the collection node, a small industrial computer workstation is set up in the nearest section;

[0021] The small industrial computer workstation is used to pre-process the collected data, analyze the lightweight signals, extract and identify the features, diagnose the more obvious faults on-site and in real time, and execute the corresponding actions at the first time;

[0022] The small industrial computer workstation communicates with the central server of the main control module to achieve collaborative control.

[0023] Preferably, the monitoring data of the existing underground monitoring system is uniformly accessed and connected to the mining cable operation situation awareness system.

[0024] Preferably, the monitoring data of the existing monitoring system includes power quality monitoring data, zero-sequence data, and temperature data.

[0025] Preferably, the main control module includes a storage database, and the preprocessed signal is transmitted to the storage database through the transmission module to provide data for cable operation status evaluation and status prediction.

[0026] Preferably, the transmission module uses 5G network, 4G network, optical fiber or underground high-speed ring network to transmit signals.

[0027] A cable insulation diagnosis method, based on the above-mentioned mining cable multi-source information perception system, comprises the following steps:

[0028] (1) Measure the voltage and current at both ends of the cable;

[0029] (2) The voltage and current data at both ends of the cable are transmitted to the cloud control center, and the voltage and current data are analyzed and calculated to obtain the relationship between the impedance and admittance per unit length of the cable. The formula is as follows:

[0030]

[0031] The power supply side of the cable is defined as the beginning of the cable, and the load side of the cable is defined as the end of the cable; where: is the voltage at the beginning of the cable per unit length, is the current per unit length at the beginning of the cable, is the voltage at the end of the cable per unit length, is the current per unit length at the end of the cable, is the voltage at a distance x from the end of the cable, is the current at a distance x from the end of the cable, γ is the line propagation constant, Z C is the wave impedance in the cable, r0 is the cable resistance per unit length, L0 is the cable inductance per unit length, g0 is the cable insulation conductivity per unit length, and C0 is the distributed capacitance per unit length;

[0032] Therefore, for a cable with a length of l, the relationship between the admittance value and the voltage and current at the beginning and end of the cable is:

[0033]

[0034] In the formula, G+jB is the admittance of the cable;

[0035] (3) The insulation status of the cable can be determined based on the cable insulation parameters.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] As described above, the multi-source information perception system and cable insulation diagnosis method for mining cables described in the present invention can evaluate the operation status of the mining cable before the failure and early warning of the corresponding failure and abnormal situation, and can grasp the operation status and development trend of the cable before the failure of the mining cable occurs. Through the diagnosis and early warning of abnormal situation, it can reduce the personal and property losses caused by the failure of the mining cable, and ensure the safety of coal mine production. The present invention only needs to measure the voltage and current values ​​at the beginning and end of the mining cable to obtain the parameters of the mining cable, and then judge the insulation state of the cable; at the same time, the monitoring data of the existing monitoring system is connected to the system, which reduces the monitoring cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0039] Figure 1 This is a schematic diagram of the entire life cycle of mining cables;

[0040] Figure 2 It is a structural schematic diagram of a multi-source information perception system for mining cables;

[0041] Figure 3 It is a single-phase distributed parameter model for mining cables;

[0042] Figure 4 It is a π-type parameter equivalent circuit;

[0043] Figure 5 It is a T-type parameter equivalent circuit;

[0044] Figure 6 Schematic diagram of dual-end synchronous sensing on a single cable. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0046] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0047] Example

[0048] Mine cable faults have long been a threat to the economic, safe and reliable operation of coal mine power grids. Therefore, it is very important to diagnose the operating status and monitor faults of mine cables. Figure 1As shown, during the entire life cycle of mining cables, by studying the operation status evaluation of coal mine cables before failure and the early warning of corresponding failures and abnormal situations, mastering the operating status and development trends of cables, diagnosing abnormal situations and giving early warnings, the purpose of preventing problems before they occur can be achieved.

[0049] This embodiment deeply integrates artificial intelligence, 5G, big data and other technologies with the safety status assessment of coal mine cable operation, forming an intelligent perception prediction, analysis and decision-making of the safety situation of cable operation in the entire mining area, real-time grasp of the safety status and development trend of cable operation, and intelligent early diagnosis and warning of cable abnormal conditions, which can effectively reduce personal and property losses caused by coal mine cable failures.

[0050] like Figure 2 As shown in the figure, combining the actual characteristics of coal mines and the IEC61850 standard, a multi-source information perception system for mining cables is established. The system includes three modules, namely, a perception module for cable operation situation perception and extraction, a transmission module, and a main control module for cable operation situation assessment and situation prediction; the perception module is the basis of the entire cable operation situation perception system.

[0051] The perception module includes a signal GPS unit, a signal acquisition unit, and a signal processing unit;

[0052] The timing signals of all GPS units in the perception module are transmitted to the main control module on the ground through the transmission module, and the main control module communicates with the satellite for timing calibration.

[0053] The transmission module transmits signals through a communication network (such as 5G network, 4G network, optical fiber or underground high-speed ring network).

[0054] The signal acquisition unit of the perception module collects multi-source information signals of the cable operation and transmits the collected signals to the signal processing unit; the signal processing unit pre-processes the collected signals, and then transmits the pre-processed signals to the cloud control center of the main control module through the transmission module, and the pre-processed signals are analyzed and calculated in the cloud control center to judge and predict the operation status of the mining cable.

[0055] Among them, the multi-source information signals collected by the signal acquisition unit include the voltage and current at the beginning and end of each line cable, as well as temperature signals, humidity signals, dust content signals, gas content signals, harmonic signals and frequency signals during cable operation, etc.

[0056] Since mining cables are long, monitoring at only one point cannot fully grasp the operating status of the entire cable, so multi-point synchronous monitoring is required. However, too many monitoring nodes will inevitably lead to excessively high monitoring costs. The circuit parameters of the cable include circuit resistance, insulation resistance to ground, line inductance, and distributed capacitance. The circuit parameters of the cable have distribution characteristics, and cables of different lengths have different distributed parameter values. Therefore, the voltage and current values ​​at any point of the cable running in the coal mine power grid are different from the voltage and current values ​​at other parts.

[0057] like Figure 3 The figure shows the distributed parameter model of a phase of the cable. The cable power supply side is defined as the cable head end, and the cable load side is defined as the cable end. The voltage and current constraint equations of the dx segment of the cable can be obtained through the model. Considering the loss of electric energy propagating in the cable, the relationship between the impedance and admittance per unit length of the cable can be deduced as follows:

[0058]

[0059] In the formula, is the voltage at the beginning of the cable per unit length, is the current per unit length at the beginning of the cable, is the voltage at the end of the cable per unit length, is the current per unit length at the end of the cable, is the voltage at a distance x from the end of the cable, is the current at a distance x from the end of the cable, γ is the line propagation constant, Z C is the wave impedance in the cable, r0 is the cable resistance per unit length, L0 is the cable inductance per unit length, g0 is the cable insulation conductivity per unit length, and C0 is the distributed capacitance per unit length;

[0060] Therefore, for a cable with a length of l, the relationship between the admittance value and the voltage and current at the beginning and end of the cable is:

[0061]

[0062] Where G+jB is the admittance of the cable.

[0063] In actual application analysis and calculation, if the distributed parameter model is used, the calculation is relatively complicated. In order to simplify the amount of calculation, this embodiment uses the π-type parameter model and the T-type parameter model for calculation.

[0064] like Figure 4 As shown, according to the simplified principle of the π-type circuit, the relationship between the cable parameters and the voltage and current at both ends is:

[0065]

[0066] like Figure 5 As shown, according to the simplified principle of T-type circuit, the relationship between cable parameters and voltage and current at both ends is:

[0067]

[0068] Where Z' is the impedance of the π-type circuit and Y' is the admittance of the π-type circuit.

[0069] It can be seen from formula (3), formula (4) and formula (5) that no matter which parameter calculation model is used, the insulation parameters of the cable can be calculated by simply measuring the voltage and current at the beginning and end of the cable at the same time.

[0070] like Figure 6 The figure shows a monitoring and sensing method using a single cable line as an example. The current and voltage values ​​are measured synchronously at the beginning and end of each line cable, and calculations are performed to obtain the cable parameters and determine the insulation status of the cable. This monitoring and sensing method performs independent calculations and analysis on each phase, and the three phases are not affected, and is not affected by the grounding method.

[0071] The characteristics of each component in a mining cable multi-source information perception system are as follows:

[0072] 1. Multi-source sensor acquisition. The signal acquisition unit collects multi-source information signals of cable operation through multi-source sensors, and establishes a multi-source sensor network to expand the perceptible boundary of cable status information, realizing the unified standardization of multi-source information signal acquisition.

[0073] 2. Core node acquisition in different sections. The signal acquisition unit collects multi-source information signals in different sections according to the cable connection points and lane distribution.

[0074] 3. Access to monitoring data from existing monitoring systems. With the help of monitoring data from existing underground monitoring systems, such as power quality monitoring data, zero-sequence data, and some temperature data, the data access method is unified, and the monitoring data from existing underground monitoring systems is accessed to the mining cable operation situation awareness system, which can reduce the collection cost.

[0075] 4. Set up edge computing workstations in different sections. According to the location of the acquisition node, a small industrial computer workstation is set up in the nearest section to pre-process the collected data and perform lightweight signal analysis, feature extraction and discrimination. For more obvious faults, real-time online diagnosis is performed on site, and corresponding actions are executed at the first time. At the same time, the small industrial computer workstation communicates with the central server of the main control module to achieve collaborative control.

[0076] 5. Massive data transmission and storage. The pre-processed data is transmitted to the storage database of the main control module through the 5G network or the underground high-speed ring network, providing support for the application of big data analysis and artificial intelligence algorithms such as cable operation status assessment and situation prediction.

[0077] This embodiment describes a cable insulation diagnosis method, based on the above-mentioned mining cable multi-source information perception system, including the following steps:

[0078] (1) Measure the voltage and current at both ends of the cable;

[0079] (2) The voltage and current data at both ends of the cable are transmitted to the cloud control center, and the voltage and current data are analyzed and calculated to obtain the relationship between the impedance and admittance per unit length of the cable. The formula is as follows:

[0080]

[0081] The power supply side of the cable is defined as the beginning of the cable, and the load side of the cable is defined as the end of the cable; where: is the voltage at the beginning of the cable per unit length, is the current per unit length at the beginning of the cable, is the voltage at the end of the cable per unit length, is the current per unit length at the end of the cable, is the voltage at a distance x from the end of the cable, is the current at a distance x from the end of the cable, γ is the line propagation constant, Z C is the wave impedance in the cable, r0 is the cable resistance per unit length, L0 is the cable inductance per unit length, g0 is the cable insulation conductivity per unit length, and C0 is the distributed capacitance per unit length;

[0082] Therefore, for a cable with a length of l, the relationship between the admittance value and the voltage and current at the beginning and end of the cable is:

[0083]

[0084] In the formula, G+jB is the admittance of the cable;

[0085] (3) The insulation state of the cable is thus determined based on the cable insulation parameters. The cable admittance value is calculated based on the voltage and current at the beginning and end of the cable using the above formula; the real part of the admittance is the cable insulation conductance, and the imaginary part is the cable insulation reactance.

[0086] The embodiments of the present invention are only used to illustrate the technical solutions of the present invention rather than to limit the present invention. It can be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A multi-source information perception system for mining cables, characterized in that: It includes a perception module for cable operation situation perception and extraction, a transmission module, and a main control module for cable operation situation assessment and situation prediction; The perception module includes a signal GPS unit, a signal acquisition unit, and a signal processing unit; The timing signal of the GPS unit is transmitted to the main control module through the transmission module, and the main control module communicates with the satellite for timing calibration; The signal acquisition unit acquires multi-source information signals of the cable operation, wherein the multi-source information signals include voltages and currents at both ends of each line cable, and then transmits the acquired signals to the signal processing unit; The signal processing unit pre-processes the collected signals, and then transmits the pre-processed signals to the cloud control center of the main control module through the transmission module, and analyzes and calculates the pre-processed signals in the cloud control center to judge and predict the operating status of the mining cable.

2. A mining cable multi-source information perception system according to claim 1, characterized in that: The signal acquisition unit collects multi-source information signals in sections according to the connection points of the cables and the distribution of the lanes.

3. A mining cable multi-source information perception system according to claim 2, characterized in that: The signal acquisition unit acquires multi-source information signals of the cable operation through a multi-source sensor.

4. A mining cable multi-source information perception system according to claim 2, characterized in that: The multi-source information signal also includes a temperature signal, a humidity signal, a dust content signal, a gas content signal, and a harmonic signal and a frequency signal during cable operation.

5. A mining cable multi-source information perception system according to claim 2, characterized in that: According to the location of the acquisition node, a small industrial computer workstation is set up in the nearest section; The small industrial computer workstation is used to pre-process the collected data, analyze the lightweight signals, extract and identify the features, diagnose the more obvious faults on-site and in real time, and execute the corresponding actions at the first time; The small industrial computer workstation communicates with the central server of the main control module to achieve collaborative control.

6. A mining cable multi-source information perception system according to claim 1, characterized in that: The monitoring data of the existing underground monitoring system will be uniformly accessed and connected to the mining cable operation situation awareness system.

7. A mining cable multi-source information perception system according to claim 6, characterized in that: The monitoring data of the existing monitoring system includes power quality monitoring data, zero-sequence data, and temperature data.

8. A mining cable multi-source information perception system according to claim 1, characterized in that: The main control module includes a storage database, and the pre-processed signal is transmitted to the storage database through the transmission module to provide data for cable operation status assessment and status prediction.

9. A mining cable multi-source information perception system according to claim 1, characterized in that: The transmission module uses 5G network, 4G network, optical fiber or underground high-speed ring network to transmit signals.

10. A cable insulation diagnosis method, based on a mining cable multi-source information perception system according to any one of claims 1 to 9, characterized in that: The steps include: (1) Measure the voltage and current at both ends of the cable; (2) The voltage and current data at both ends of the cable are transmitted to the cloud control center, and the voltage and current data are analyzed and calculated to obtain the relationship between the impedance and admittance per unit length of the cable. The formula is as follows: The power supply side of the cable is defined as the beginning of the cable, and the load side of the cable is defined as the end of the cable; where: is the voltage at the beginning of the cable per unit length, is the current per unit length at the beginning of the cable, is the voltage at the end of the cable per unit length, is the current per unit length at the end of the cable, is the voltage at a distance x from the end of the cable, is the current at a distance x from the end of the cable, γ is the line propagation constant, Z C is the wave impedance in the cable, r0 is the cable resistance per unit length, L0 is the cable inductance per unit length, g0 is the cable insulation conductivity per unit length, and C0 is the distributed capacitance per unit length; Therefore, for a cable with a length of l, the relationship between the admittance value and the voltage and current at the beginning and end of the cable is: In the formula, G+jB is the admittance of the cable; (3) The insulation status of the cable can be determined based on the cable insulation parameters.

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