Underground coal mine 3DR electric leakage detection protection method

Abstract

The invention provides a coal mine underground 3DR electric leakage detection protection method, which comprises the following steps of: constructing an auxiliary star point connected with a system by using three-phase half-waves of a power supply system of a converter substation through a common cathode or common anode connecting wire; a residual current Hall sensor is used for detecting electric leakage residual current of different harmonic waves, and a 3DR electric leakage insulation resistance measurement technology is discriminated based on a Fourier algorithm; according to the harmonic component, the electric leakage resistance, the electric leakage value and the area of the frequency converter of the power supply system of the coal mine mobile converter substation can be judged, and alarm protection is judged; and the harmonic current is dynamically detected, so that selective leakage protection can be realized. According to the invention, through a 3DR electric leakage technology, electric leakage detection and instantaneous protection of the frequency converter are realized; selective earth leakage protection is realized according to the detection of the fundamental component and the harmonic wave; through harmonic leakage current and fundamental wave detection system distributed capacitance, electric leakage protection and capacitive current accurate judgment of power supply equipment in a coal mine power supply system are realized.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine power supply protection, and in particular to a 3DR leakage detection and protection method for underground coal mines. Background Art

[0002] In the power supply system of coal mines, the stability and safety of the power supply system are of vital importance. With the expansion of the fully mechanized mining surface in coal mines and the widespread use of large-capacity and high-energy-consuming electrical equipment underground, energy saving and safety issues must be considered. With the rapid development of frequency conversion technology, frequency converters are used on a large scale in coal mines. Their high efficiency and energy saving, frequency conversion speed regulation, and remote starting are considered to be one of the most ideal and promising speed regulation methods; the high-order harmonics brought by the addition of frequency converters have a great influence on the detection of three-phase insulation resistance to ground. Because of the unique structure and working principle of the frequency converter, it is easy to generate huge harmonic components in the system, which leads to error states and fault characteristics in the leakage system underground in coal mines, causing great harmonic pollution. The original zero-sequence current and zero-sequence voltage protections fail; the typical additional DC leakage detection cannot be put into use due to the influence of the DC component; the injection method is used for leakage detection, which is also affected by harmonics and carriers, and the response time cannot meet the time limit requirements of coal mines. Pre-detection can only be carried out by leakage locking. The leakage current on the inverter output side is related to the inverter output voltage, the insulation resistance to ground on the output side, the parasitic capacitance and the carrier frequency of its output voltage. As the carrier frequency increases, the capacitance to ground increases, the leakage current value increases, and the risk of electric shock increases. Leakage protection is one of the three major protection measures for power supply in coal mines. If the protection does not work correctly and sensitively, it will cause great potential hidden dangers to the safety of underground workers in the humid and harsh environment of coal mines.

[0003] Prior art 1, application number: CN 202410638225.3 discloses a mine leakage test switching device. In order to solve the problems of cumbersome operation, low efficiency, prominent safety hazards, high skill requirements for operators and reliance on manual cooperation and supervision in the remote leakage test under the prior art, the test switching device is installed in an explosion-proof resistor box and controlled by a CPU control module. The external command signal allows the test switching device to complete the low-voltage leakage test. The command signal of the superior control system is received through the CPU control module, and the leakage test procedure is automatically executed. There is no need to manually operate the switch and cross-connect the test resistor. The device can detect abnormal conditions in time and take corresponding measures through the superior control system to eliminate safety hazards. Although it overcomes the limitations of traditional test methods, it can completely replace traditional remote leakage test methods, and can more realistically test the leakage protection and leakage lockout of various levels of the coal mine underground power supply system; however, its function is relatively single and lacks the function of leakage detection and protection, resulting in the safety of mine leakage test to be further improved.

[0004] Prior art 2, application number: CN 202211403211.0 discloses a leakage test device and method suitable for underground feeder switches in coal mines, wherein the device includes a remote controller for wirelessly controlling the working mode of the remote leakage test device and the working mode of the near-end leakage test device; the remote leakage test device is used to simulate the leakage of the cable to be tested or the electrical equipment near the electrical equipment under the working mode controlled by the remote controller; wherein the cable to be tested is the connecting cable between the feeder switch and the electrical equipment; the near-end leakage test device is used to simulate the leakage of the cable to be tested near the feeder switch under the working mode controlled by the remote controller, and close or reset the feeder switch under the working mode controlled by the remote controller. Although it is possible to detect whether the protection action of the feeder switch is sensitive and reliable when the cables at different positions are leaking or the electrical equipment is leaking without being close to the feeder switch; however, the use of wireless control makes the response speed of leakage detection slow, which affects safety to a certain extent.

[0005] Prior art three, application number: CN202211282407.9 discloses a mine low-voltage power grid leakage protection test system, the system includes: power distribution cabinet, high-open leakage test cabinet, main feed test cabinet, sub-feed test cabinet, tested protector, tested main feed switch, tested sub-feed switch. Although it can realize leakage detection of various protectors, main feed switches, and sub-feed switches in the mine, thereby ensuring the safety of the underground power system of the coal mine; but its structure is complex, the operation is cumbersome, and the cost and time of leakage detection are increased.

[0006] At present, the existing technologies 1, 2 and 3 have the problem that the higher the carrier frequency, the greater the capacitance to the ground, the greater the leakage current value, and the greater the risk of electric shock. Therefore, the present invention provides a 3DR leakage detection and protection method for underground coal mines. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a 3DR leakage detection and protection method for underground coal mines, comprising the following steps:

[0008] Using the three-phase half-wave of the power supply system of the transformer substation, an auxiliary star point connected to the power supply system of the transformer substation is constructed through common cathode or common anode wiring;

[0009] The residual current Hall sensor is used to detect residual currents of different harmonics, and the 3DR leakage current measurement insulation resistance technology is identified based on the Fourier algorithm;

[0010] According to the harmonic components, the leakage resistance of the inverter of the coal mine mobile converter substation power supply system can be quickly determined to judge the leakage value and area and to give a judgment and alarm protection; and the harmonic current can be dynamically detected to achieve selective leakage protection.

[0011] Optionally, the process of constructing an auxiliary star point connected to the power supply system of the transformer substation includes the following steps:

[0012] The three-phase voltage is rectified by a three-phase half-wave rectifier circuit, which is composed of three groups of diodes, corresponding to the positive half cycle or negative half cycle of the three-phase voltage respectively; in the three-phase half-wave rectifier circuit, the diodes use a common cathode or common anode connection method to convert the three-phase voltage into a DC voltage, and at the same time form an auxiliary star point;

[0013] After the voltage of the power supply system of the transformer substation is rectified, a DC voltage is formed at the auxiliary star point, and the DC voltage is filtered; the DC voltage is the average value of the three-phase voltage, reflecting the overall voltage level of the power supply system of the transformer substation;

[0014] Through Fourier transform, the waveform of the DC voltage is decomposed into components of different frequencies. The fundamental component corresponds to the basic frequency of the power supply system of the DC substation, while the carrier component corresponds to the high-frequency component. The fundamental component and the carrier component are extracted separately through a bandpass filter. The current changes in the power supply system are monitored in real time through a Hall current sensor, and the waveform of the residual leakage current is extracted.

[0015] Optionally, the process of decomposing the DC voltage waveform into components of different frequencies comprises the following steps:

[0016] Obtain a rectified and filtered DC voltage signal from the auxiliary star point, and use Fourier transform to convert the pre-processed DC voltage signal from the time domain to the frequency domain. The DC voltage signal is decomposed into components of different frequencies, each component corresponding to a specific frequency and amplitude;

[0017] In the frequency domain, the DC voltage signal is decomposed into multiple frequency components, including fundamental wave component and carrier wave component; the fundamental wave component corresponds to the basic frequency of the power supply system of the DC substation and reflects the basic voltage characteristics; the carrier wave component is a high-frequency component and reflects the nonlinear characteristics;

[0018] The frequency domain signal is processed using a bandpass filter to extract the fundamental component and the carrier component respectively; the Hall current sensor measures the instantaneous value of the current and decomposes the current signal into components of different frequencies through Fourier transform; by analyzing the components, the waveform of the residual leakage current is extracted.

[0019] Optionally, the process of identifying the 3DR leakage current measurement insulation resistance technology based on the Fourier algorithm includes the following steps:

[0020] The Hall sensor collects the residual current signal in the power supply system in real time, including fundamental current and harmonic current components; the Hall sensor performs preliminary processing on the collected residual current signal to separate the harmonic currents of different frequencies;

[0021] The pre-processed current signal is input into Fourier transform to decompose the amplitude and phase information of each harmonic;

[0022] According to the results of Fourier transform, the amplitude and phase of each harmonic current are analyzed; combined with the circuit parameters of the power supply system of the converter substation, the insulation resistance value in the 3DR leakage measurement is calculated; based on the calculated insulation resistance value, it is determined whether there is leakage.

[0023] Optionally, the process of decomposing the amplitude and phase information of each harmonic includes the following steps:

[0024] The preprocessed current signal is input into Fourier transform to convert the time domain signal into a frequency domain signal and obtain different frequency components contained in the current signal;

[0025] Perform an integral operation on the current signal, and extract the amplitude and phase information of each frequency component in the current signal by performing inner product with sine and cosine functions of different frequencies;

[0026] In the Fourier transform result, each frequency point corresponds to a complex value. The modulus of the complex value represents the amplitude of the frequency component, and the phase angle represents the phase of the frequency component, decomposing the amplitude and phase of each harmonic in the current signal.

[0027] Optionally, the process of extracting the amplitude and phase information of each frequency component in the current signal includes the following steps:

[0028] Using discrete Fourier transform, the inner product of the current signal and the complex exponential function of different frequencies is calculated; the current signal is decomposed into sine and cosine components of different frequencies, and the frequency domain signal is decomposed into complex values;

[0029] Calculate the amplitude and phase of frequency components using complex values;

[0030] For each harmonic in the current signal, its amplitude and phase are extracted by calculating the specific frequency point.

[0031] Optionally, the process of determining whether there is leakage includes the following steps:

[0032] A mathematical model for calculating insulation resistance is constructed based on the basic principle of the circuit. The resistance, capacitance and inductance parameters in the circuit are added to the mathematical model, and the amplitude and phase information of the harmonic current are combined;

[0033] Based on the parameter, amplitude and phase information, the calculation formula of insulation resistance is obtained;

[0034] After the insulation resistance value is calculated, it is compared with the preset safety threshold to determine whether there is leakage.

[0035] Optionally, the process of quickly determining the leakage value and area and performing judgment alarm protection includes the following steps:

[0036] According to the distribution and change trend of the current, combined with the actual layout of the coal mine and the topological structure of the power supply system, the specific area where the leakage occurs can be located;

[0037] When leakage is detected, the alarm mechanism is triggered and relevant personnel are notified to handle the problem. The alarm information includes the amplitude, occurrence time and specific location of the leakage current. At the same time, the harmonic current is dynamically monitored to protect specific areas or equipment from leakage.

[0038] Record the results of each leakage detection, including the characteristics of the leakage current, location information and processing results.

[0039] Optionally, the process of locating the specific area where the leakage occurs includes the following steps:

[0040] The monitoring point of the current anomaly is matched with the physical location in the underground layout. The current anomaly appears at the monitoring point of a power supply line. According to the geographical information of the underground layout, the actual physical location corresponding to the monitoring point is determined;

[0041] The propagation path of abnormal current is analyzed by using the topology of the power supply system. The topology describes the connection relationship between various devices and lines in the power supply system. By analyzing the propagation path of abnormal current, the source of abnormal current can be determined. If the abnormal current occurs on a main power supply line, the branch of the line is further traced to analyze whether the abnormal current is caused by a branch line or a certain device.

[0042] After completing the matching of the current abnormality area with the geographic information of the underground layout and the current path analysis in the topological structure, information fusion is performed; the area of ​​current abnormality is combined with the geographic information of the underground layout and the topological structure of the power supply system to form a comprehensive positioning model; it is determined that the current abnormality occurs on a specific power supply branch or on a specific device.

[0043] Optionally, the process of forming a comprehensive positioning model includes the following steps:

[0044] Based on the fused information data, a comprehensive positioning model framework is designed, including input layer, processing layer and output layer; the input layer receives geographic information, topological structure and current anomaly data; the processing layer performs data analysis and feature extraction; the output layer generates the positioning results of current anomalies;

[0045] In the processing layer, feature extraction is performed on the input information data. The extracted features include the intensity of the current anomaly, the propagation path and the working status of the equipment. The propagation path of the current anomaly is analyzed using the topological structure. The source and propagation direction of the current anomaly are determined through path analysis. If the current anomaly appears on a main power supply line, the line branches are traced to analyze whether the current anomaly is caused by a branch line or a certain device.

[0046] Based on the results of feature extraction and path analysis, positioning calculation is performed, and the specific location of the current anomaly is determined by the positioning algorithm based on the topological structure; the result of the positioning calculation is output to the result output layer, and the output result is a specific physical location, a certain lane or a certain working surface; it is presented in the form of a graphic.

[0047] The present invention is based on 3DR leakage detection technology, uses system voltage to establish auxiliary star points through three-phase half-wave, common cathode or common anode, and detects the real-time resistance value of the leakage resistor through a high-precision AC / DC Hall residual current sensor; based on 3DR leakage detection technology, 6-pulse and 12-pulse leakage detection is realized; based on 3DR leakage detection technology, insulation detection of different voltage levels of IT power supply system is realized; based on 3DR leakage detection technology, leakage lock detection of the system is realized; based on 3DR leakage detection technology, a high-performance MCU is used, and the real-time collected leakage data is analyzed by Fourier series on harmonics and combined with a special algorithm, so that 3DR leakage detection and protection can be realized quickly (the real-time response speed is much better than the traditional leakage detection method); based on the Fourier algorithm, the fundamental frequency is extracted to realize the detection of system distributed capacitance.

[0048] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0049] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0051] Figure 1 This is a flow chart of the 3DR leakage detection and protection method for underground coal mines in Example 1 of the present invention;

[0052] Figure 2 A flowchart of constructing an auxiliary star point connected to a power supply system of a transformer substation in Embodiment 2 of the present invention;

[0053] Figure 3 is a process diagram of decomposing a DC voltage waveform into components of different frequencies in Embodiment 3 of the present invention;

[0054] Figure 4 A process diagram for identifying the technology of 3DR leakage current measurement insulation resistance based on Fourier algorithm in Example 4 of the present invention;

[0055] Figure 5 A process diagram of decomposing the amplitude and phase information of each harmonic in Embodiment 5 of the present invention;

[0056] Figure 6 A process diagram of extracting the amplitude and phase information of each frequency component in the current signal in Embodiment 6 of the present invention;

[0057] Figure 7 This is a process diagram for determining whether there is leakage in Embodiment 7 of the present invention;

[0058] Figure 8 This is a process diagram for quickly determining the leakage value and area and performing judgment and alarm protection in Example 8 of the present invention;

[0059] Fig. 9 This is a process diagram for locating a specific area where leakage occurs in Example 9 of the present invention;

[0060] Fig.10 A process diagram of forming a comprehensive positioning model in Embodiment 10 of the present invention;

[0061] Fig.11 This is a schematic diagram of the 3DR leakage detection and protection method for underground coal mines in Example 11 of the present invention;

[0062] Fig.12 This is a schematic diagram of leakage detection of a 6-pulse frequency converter 3DR of a power supply system of a dynamic current transformer substation in an underground coal mine in Embodiment 12 of the present invention;

[0063] Fig.13 This is a schematic diagram of leakage detection of the pulse inverter 3DR of the power supply system 12 of the dynamic current transformer substation in the coal mine underground in embodiment 13 of the present invention. DETAILED DESCRIPTION

[0064] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0065] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in this article refers to and includes any or all possible combinations of one or more associated listed items.

[0066] When the following description relates to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are only examples of devices and methods consistent with some aspects of the present application. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and do not have to be used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0067] Example 1: Figure 1 As shown, the embodiment of the present invention provides a 3DR leakage detection and protection method for underground coal mines, comprising the following steps:

[0068] S100: Using the three-phase half-wave of the power supply system of the transformer substation, an auxiliary star point connected to the power supply system of the transformer substation is constructed through common cathode or common anode wiring;

[0069] S200: Use residual current Hall sensors to detect residual currents of different harmonics, and identify the 3DR leakage current measurement insulation resistance technology based on Fourier algorithm;

[0070] S300: Based on the harmonic components, the leakage resistance of the inverter of the coal mine mobile converter substation power supply system can be quickly determined to determine the leakage value and area and to provide judgment and alarm protection; the harmonic current can be dynamically detected to achieve selective leakage protection.

[0071] The working principle and beneficial effects of the above technical solution are as follows: the present embodiment firstly utilizes the three-phase half-wave of the power supply system of the converter substation to construct an auxiliary star point connected to the system through common cathode or common anode wiring; secondly, the residual current Hall sensor is used to detect the residual current of different harmonics, and the 3DR leakage measurement insulation resistance technology is identified based on the Fourier algorithm; finally, according to the harmonic component, the leakage resistance of the inverter of the power supply system of the mobile converter substation of the coal mine can be realized, the leakage value and area can be quickly judged, and the judgment alarm protection can be performed; and the harmonic current can be dynamically detected to realize selective leakage protection. Step S100 of the above scheme constructs an auxiliary star point, and constructs an auxiliary star point connected to the system through the three-phase half-wave of the power supply system of the converter substation, using common cathode or common anode wiring; it can provide a stable reference point, making the current detection and analysis more accurate. Significance: The construction of the auxiliary star point provides a basis for subsequent leakage detection, ensuring the stability and reliability of the detection system; it is particularly important for the complex and dangerous environment of the coal mine underground, and can effectively improve the accuracy of detection and the stability of the system. Step S200 uses the residual current Hall sensor for detection, uses the residual current Hall sensor to detect the residual current of different harmonics, and identifies the 3DR leakage measurement insulation resistance technology based on the Fourier algorithm; it can accurately detect the harmonic components of the leakage current, and analyze it through the Fourier algorithm to accurately judge the leakage situation. Significance: Through accurate harmonic analysis, the specific situation of the leakage can be effectively identified, including the intensity and location of the leakage; it is of great significance for timely discovery and handling of leakage problems and prevention of accidents. Step S300 quickly determines the leakage value and area and performs alarm protection. According to the harmonic component, the leakage resistance of the inverter of the power supply system of the coal mine mobile converter substation is quickly determined, and the judgment alarm protection is performed; at the same time, the harmonic current is dynamically detected to achieve selective leakage protection; it can monitor the leakage situation in real time and take protective measures quickly when abnormalities are found. Significance: Rapidly determine the leakage value and area, and provide alarm protection, which can effectively prevent the expansion of leakage accidents and ensure the safe operation of coal mines; dynamically detect harmonic currents and realize selective leakage protection, further improving the safety and reliability of the system.

[0072] This embodiment, through the analysis of underground leakage protection, invented a 3DR (3D, amplitude: the size of the current, frequency: the fluctuation frequency of the current, phase: the phase relationship of the current; R residual, refers to the additional current outside the normal working current) leakage detection and protection method for coal mines, calculated the leakage current of the system and equipment inverter, and used harmonics for leakage protection. The 3DR leakage detection method is a brand-new leakage detection technology, which uses three-phase half-wave, through common cathode or common anode wiring, to build an auxiliary star point connected to the system, and uses residual current detection Hall sensors to detect the residual leakage current of harmonics in each frequency band. Based on the Fourier algorithm, the 3DR leakage measurement data is used to calculate the insulation resistance of the current system in real time. Quickly judge the leakage value and area and issue an alarm and protection. Because any periodically changing waveform can be decomposed into a sine wave component containing a fundamental frequency and a series of harmonics that are integer multiples of the fundamental. The inverter harmonic is a sine wave component of a periodic quantity, and its frequency is an integer multiple of the fundamental frequency 50Hz. The amplitude of the inverter harmonic and the phase relationship of the harmonic relative to the fundamental are important factors affecting this periodic quantity. Through this harmonic analysis, the insulation detection of 6-pulse and 12-pulse inverters has a fast response. The 3DR leakage protection method has a higher social promotion, especially for leakage protection of IT power supply systems.

[0073] This embodiment uses the harmonics generated when the protected equipment leaks electricity to perform leakage detection. It includes: a mobile converter substation based on the inverter power supply system: network measurement, valve side, and leakage detection of the output cable to the motor end; based on 3DR leakage detection technology, the system voltage is used to establish an auxiliary star point through three-phase half-wave, common cathode or common anode, and the real-time resistance value of the leakage resistor is detected through a high-precision AC / DC Hall residual current sensor; based on 3DR leakage detection technology, 6-pulse and 12-pulse leakage detection is realized; based on 3DR leakage detection technology, insulation detection of different voltage levels of IT power supply system is realized; based on 3DR leakage detection technology, leakage lock detection of the system is realized; based on 3DR leakage detection technology, high-performance MCU is used, and the Fourier series analysis of harmonics is used through real-time collected leakage data and combined with a special algorithm, which can quickly (the real-time response speed is much better than the traditional leakage detection method) realize 3DR leakage detection and protection; based on the Fourier algorithm, the fundamental frequency is extracted to realize the detection of system distributed capacitance.

[0074] This embodiment uses 3DR leakage technology to achieve leakage detection and instantaneous protection of the inverter; and realizes selective leakage protection based on the detection of fundamental components and harmonics; through the distributed capacitance of the harmonic leakage current and fundamental detection system, it can realize leakage protection of power supply equipment and accurate judgment of capacitive current in the coal mine power supply system; ensure the safety of inverter leakage protection, and add a leakage protection method for power supply systems with ungrounded neutral points.

[0075] In summary, this embodiment can effectively improve the safety and reliability of the underground power supply system in coal mines by constructing auxiliary star points, accurately detecting harmonic currents, quickly judging leakage values ​​and areas, and performing alarm protection; it is of great significance for ensuring the life safety of coal miners and the normal operation of equipment.

[0076] Example 2: Figure 2 As shown, based on Example 1, the process of constructing an auxiliary star point connected to the power supply system of the transformer substation provided in the embodiment of the present invention includes the following steps:

[0077] S101: rectifying the three-phase voltage through a three-phase half-wave rectifier circuit, the three-phase half-wave rectifier circuit is composed of three groups of diodes, corresponding to the positive or negative half cycle of the three-phase voltage respectively; in the three-phase half-wave rectifier circuit, the diodes adopt a common cathode or common anode connection mode to convert the three-phase voltage into a DC voltage, and form an auxiliary star point at the same time;

[0078] Among them, the auxiliary star point is a common reference point in the rectifier circuit, which is connected to the three-phase voltage of the power supply system of the transformer substation; the auxiliary star point provides a stable reference benchmark for voltage and current detection;

[0079] S102: After the voltage of the power supply system of the transformer substation is rectified, a DC voltage is formed at the auxiliary star point, and the DC voltage is filtered; the DC voltage is the average value of the three-phase voltage, reflecting the overall voltage level of the power supply system of the transformer substation;

[0080] S103: Decompose the DC voltage waveform into components of different frequencies through Fourier transform, wherein the fundamental component corresponds to the basic frequency of the power supply system of the DC substation, and the carrier component corresponds to the high-frequency component; extract the fundamental component and the carrier component respectively through a bandpass filter; monitor the current change in the power supply system in real time through a Hall current sensor, and extract the waveform of the residual leakage current.

[0081] The working principle and beneficial effects of the above technical solution are as follows: the present embodiment firstly rectifies the three-phase voltage through a three-phase half-wave rectifier circuit, the three-phase half-wave rectifier circuit is composed of three groups of diodes, corresponding to the positive or negative half cycle of the three-phase voltage respectively; in the three-phase half-wave rectifier circuit, the diodes adopt a common cathode or common anode wiring method to convert the three-phase voltage into a DC voltage, and form an auxiliary star point at the same time; wherein the auxiliary star point is a common reference point in the rectifier circuit, connected to the three-phase voltage of the power supply system of the transformer substation; a stable reference benchmark is provided for voltage and current detection through the auxiliary star point; secondly, the transformer After the voltage of the power supply system of the transformer substation is rectified, a DC voltage is formed at the auxiliary star point, and the DC voltage is filtered; the DC voltage is the average value of the three-phase voltage, reflecting the overall voltage level of the power supply system of the transformer substation; finally, through Fourier transform, the waveform of the DC voltage is decomposed into components of different frequencies, the fundamental component corresponds to the basic frequency of the power supply system of the transformer substation, and the carrier component corresponds to the high-frequency component; through the bandpass filter, the fundamental component and the carrier component are extracted respectively; through the Hall current sensor, the current change in the power supply system is monitored in real time, and the waveform of the residual leakage current is extracted. Step S101 of the above scheme is the formation of the three-phase half-wave rectifier circuit and the auxiliary star point. Through the three-phase half-wave rectifier circuit, the three-phase AC voltage is converted into DC voltage; the diode in the rectifier circuit is turned on in the positive half cycle of each phase, and the positive half wave of the AC voltage is converted into DC voltage; through the common cathode or common anode wiring method, a common reference point, namely the auxiliary star point, is formed. The auxiliary star point is a stable reference point in the rectifier circuit and is connected to the three-phase voltage of the power supply system of the transformer substation. Significance achieved: The auxiliary star point provides a stable reference benchmark for voltage and current detection, which is crucial for accurately measuring and controlling the voltage and current of the converter substation; by forming an auxiliary star point, the circuit design is simplified, making the detection of voltage and current more direct and efficient. Step S102: Filtering of DC voltage. After the voltage of the converter substation power supply system is rectified, a DC voltage is formed at the auxiliary star point; the DC voltage is the average value of the three-phase voltage and reflects the overall voltage level of the power supply system; the DC voltage is filtered to remove the AC component, making the DC voltage smoother and more stable. Significance achieved: The DC voltage after filtering is more stable, which helps to improve the stability and reliability of the power supply system; the stable DC voltage provides a more accurate reference benchmark for subsequent voltage and current detection.Step S103 Fourier transform and current monitoring: Through Fourier transform, the waveform of the DC voltage is decomposed into components of different frequencies; the fundamental component corresponds to the basic frequency of the power supply system of the DC substation, and the carrier component corresponds to the high-frequency component; through the bandpass filter, the fundamental component and the carrier component are extracted respectively, which is helpful to analyze the frequency characteristics and high-frequency interference of the power supply system; through the Hall current sensor, the current changes in the power supply system are monitored in real time, and the waveform of the residual leakage current is extracted, which is helpful to timely discover and deal with current anomalies. Significance achieved: Through Fourier transform and bandpass filter, the frequency characteristics and high-frequency interference of the power supply system can be accurately analyzed, which is helpful to optimize the performance of the power supply system; real-time monitoring of current changes and extraction of the waveform of the residual leakage current are helpful to timely discover and deal with current anomalies and improve the safety of the power supply system.

[0082] In summary, the various steps of this embodiment together constitute a complete auxiliary star point construction process, which not only improves the stability and reliability of the power supply system, but also provides a stable reference benchmark for accurate detection of voltage and current, and ultimately improves the performance and safety of the entire power supply system of the transformer substation.

[0083] Example 3: Figure 3 As shown, based on Example 2, the process of decomposing the waveform of a DC voltage into components of different frequencies provided in the embodiment of the present invention includes the following steps:

[0084] S1031: obtaining a rectified and filtered DC voltage signal from the auxiliary star point, converting the pre-processed DC voltage signal from the time domain to the frequency domain using Fourier transform, and decomposing the DC voltage signal into components of different frequencies, each component corresponding to a specific frequency and amplitude;

[0085] The formula for Fourier transform is:

[0086]

[0087] Combined with the frequency domain differential characteristics, the nth-order derivative of the DC voltage signal is expressed in the frequency domain as:

[0088]

[0089] Further combined with the convolution theorem, the convolution of the DC voltage signal is expressed in the frequency domain as:

[0090]

[0091] Combining Laplace transform with Fourier transform, the frequency domain representation of the dynamic signal is:

[0092]

[0093] Where: s = σ + jω is a complex frequency variable, σ is used to process the transient response of the DC voltage signal, and jω is used to process the steady-state frequency characteristics of the DC voltage signal; X(ω) represents the frequency domain representation of the DC voltage signal, which represents the amplitude and phase information of the DC voltage signal at the frequency ω; x(t) represents the time domain signal, which represents the input dynamic signal (such as voltage or current); jω represents the frequency component, which represents the complex frequency characteristics of the DC voltage signal; Represents the nth order derivative of the time domain signal, indicating the dynamic change characteristics of the DC voltage signal; (jω) n X(ω) represents the nth order differential of the frequency domain signal, which represents the dynamic characteristics of the DC voltage signal in the frequency domain; x(t)*h(t) represents the convolution of the time domain signal, which represents the superposition of the DC voltage signal and the system response; X(ω)·H(ω) represents the product of the frequency domain signal, which represents the result of the convolution in the frequency domain; X(s) represents the Laplace transform representation of the DC voltage signal, which combines the transient and steady-state characteristics;

[0094] S1032: In the frequency domain, the DC voltage signal is decomposed into multiple frequency components, including a fundamental component and a carrier component; the fundamental component corresponds to the basic frequency of the power supply system of the transformer substation and reflects the basic voltage characteristics; the carrier component is a high-frequency component and reflects the nonlinear characteristics;

[0095] S1033: Process the frequency domain signal using a bandpass filter to extract the fundamental component and the carrier component respectively; use the Hall current sensor to measure the instantaneous value of the current, and decompose the current signal into components of different frequencies through Fourier transform; extract the waveform of the residual leakage current by analyzing the components.

[0096] The working principle and beneficial effects of the above technical solution are as follows: This embodiment first obtains a rectified and filtered DC voltage signal from the auxiliary star point, and uses Fourier transform to convert the preprocessed DC voltage signal from the time domain to the frequency domain, and the DC voltage signal is decomposed into components of different frequencies, each component corresponding to a specific frequency and amplitude; secondly, in the frequency domain, the DC voltage signal is decomposed into multiple frequency components, including a fundamental component and a carrier component; the fundamental component corresponds to the basic frequency of the power supply system of the transformer substation and reflects the basic voltage characteristics; the carrier component is a high-frequency component and reflects the nonlinear characteristics; finally, a bandpass filter is used to process the frequency domain signal to extract the fundamental component and the carrier component respectively; the Hall current sensor measures the instantaneous value of the current, and decomposes the current signal into components of different frequencies through Fourier transform; by analyzing the components, the waveform of the residual leakage current is extracted. Step S1031 of the above scheme is signal acquisition and Fourier transform, which obtains the rectified and filtered DC voltage signal from the auxiliary star point to ensure the stability and purity of the signal and avoid noise interference; the pre-processed DC voltage signal is converted from the time domain to the frequency domain through Fourier transform, and the complex time domain signal is decomposed into multiple frequency components, each component corresponding to a specific frequency and amplitude. The significance achieved: Through Fourier transform, the DC voltage signal is decomposed into multiple frequency components, which is convenient for further analysis and processing; it provides a basis for frequency domain analysis and filtering processing; frequency domain analysis can reveal the frequency characteristics of the signal and help identify the fundamental component and carrier component in the signal, so as to better understand the composition and changes of the signal. Step S1032 is frequency domain decomposition and component identification. In the frequency domain, the DC voltage signal is decomposed into multiple frequency components, including the fundamental component and the carrier component; the fundamental component corresponds to the basic frequency of the power supply system and reflects the basic voltage characteristics; the carrier component is a high-frequency component, reflecting the nonlinear characteristics. Significance achieved: By identifying the fundamental component and the carrier component, the basic characteristics and nonlinear characteristics of the DC voltage signal can be deeply analyzed to help understand the dynamic changes and potential problems of the signal; identifying the carrier component helps to detect the nonlinear components in the signal, which may indicate harmonics or faults in the system. Step S1033 filtering processing and leakage detection, using a bandpass filter to process the frequency domain signal, extract the fundamental component and the carrier component respectively, and further analyze the frequency characteristics of the signal; measure the instantaneous value of the current through the Hall current sensor, and use Fourier transform to decompose the current signal into components of different frequencies, and extract the waveform of the residual leakage current. Significance achieved: Through filtering processing, unnecessary frequency components can be removed, useful signal components can be retained, and the purity and analysis accuracy of the signal can be improved; extracting the waveform of the residual leakage current can help detect insulation faults in electrical equipment or lines, timely discover and deal with potential safety hazards, and ensure the safe operation of the system.

[0097] In summary, this embodiment converts the signal from the time domain to the frequency domain through Fourier transform, decomposes it into components of different frequencies, and then performs filtering and component identification to finally achieve in-depth analysis of signal characteristics and fault detection. This not only improves the accuracy and efficiency of signal analysis, but also provides strong support for the safe operation and fault diagnosis of the system.

[0098] Example 4: Figure 4 As shown, based on Example 3, the process of identifying the technology of 3DR leakage current measurement insulation resistance based on Fourier algorithm provided in the embodiment of the present invention includes the following steps:

[0099] S201: The Hall sensor collects the residual current signal in the power supply system in real time, including fundamental current and harmonic current components; the Hall sensor performs preliminary processing on the collected residual current signal to separate harmonic currents of different frequencies;

[0100] S202: Input the preprocessed current signal into Fourier transform to decompose the amplitude and phase information of each harmonic;

[0101] S203: Analyze the amplitude and phase of each harmonic current according to the result of Fourier transform; calculate the insulation resistance value in 3DR leakage measurement in combination with the circuit parameters of the power supply system of the converter substation; and determine whether there is leakage according to the calculated insulation resistance value.

[0102] The working principle and beneficial effects of the above technical scheme are as follows: In this embodiment, the Hall sensor first collects the residual current signal in the power supply system in real time, including the fundamental current and harmonic current components; the Hall sensor performs preliminary processing on the collected residual current signal to separate the harmonic currents of different frequencies; secondly, the pre-processed current signal is input into the Fourier transform to decompose the amplitude and phase information of each harmonic; finally, according to the result of the Fourier transform, the amplitude and phase of each harmonic current are analyzed; combined with the circuit parameters of the power supply system of the transformer substation, the insulation resistance value in the 3DR leakage measurement is calculated; according to the calculated insulation resistance value, it is judged whether there is leakage. Step S201 of the above scheme is real-time collection and preliminary processing of the Hall sensor; the Hall sensor can collect the residual current signal in the power supply system in real time to ensure the timeliness and accuracy of the data; through preliminary processing, the fundamental current (such as 50Hz or 60Hz) and the harmonic current (such as the 3rd, 5th, and 7th harmonics) can be separated to provide a clear signal basis for subsequent analysis; the Hall sensor has a strong anti-interference ability, which can effectively filter out environmental noise and electromagnetic interference to ensure the purity of the signal. The significance achieved: The separated signal can provide clear frequency domain data for Fourier transform, avoiding the influence of aliasing and interference on the analysis results; by separating the harmonic current, the influence of each harmonic on the insulation resistance can be analyzed more accurately, thereby improving the accuracy of leakage detection; real-time acquisition and processing of signals can timely discover abnormal conditions in the power supply system and provide data support for protection actions. Step S202 Fourier transform analysis, through Fourier transform, the time domain signal is converted into a frequency domain signal, and the amplitude and phase information of each harmonic are decomposed; the characteristics of the fundamental wave and higher harmonics can be analyzed at the same time, and the current distribution of the power supply system can be fully reflected; through the spectrum diagram or harmonic analysis diagram, the components of each harmonic are intuitively displayed, which is convenient for analysis and judgment. The significance achieved: Fourier transform can reveal the distribution law of each harmonic in the power supply system, and provide a scientific basis for the calculation of insulation resistance; through the results of Fourier transform, the amplitude and phase of each harmonic can be accurately extracted, and accurate data input can be provided for the subsequent insulation resistance calculation; Fourier transform can quickly process complex signals, greatly improving the efficiency and accuracy of data analysis. Step S203 insulation resistance calculation and leakage judgment, combined with the results of Fourier transform and the circuit parameters of the power supply system, can accurately calculate the insulation resistance value in the 3DR leakage measurement; can adjust the calculation model in real time according to the dynamic changes of harmonic current to ensure the accuracy of the calculation results; based on the calculated insulation resistance value, determine whether there is leakage and trigger the corresponding protection action.Significance achieved: By accurately calculating the insulation resistance, it is possible to more accurately determine whether there is leakage in the power supply system to avoid misjudgment or missed judgment; timely detection of leakage and triggering of protection actions can effectively prevent leakage accidents and ensure the safe operation of the power supply system; according to the distribution characteristics of harmonic currents, selective leakage protection can be achieved to avoid large-scale power outages or false operations.

[0103] In summary, this embodiment forms a complete signal processing chain from signal acquisition, preliminary processing, Fourier transform to insulation resistance calculation, ensuring high quality and high precision of data; by dynamically analyzing the changes in harmonic current, the calculation model can be adjusted in real time to achieve accurate leakage detection and protection; the high efficiency of the Fourier algorithm and the reliability of the Hall sensor ensure the rapid response and stable operation of the entire process. This embodiment can effectively prevent leakage accidents and ensure the safe operation of the underground power supply system in coal mines through precise leakage detection and protection; the analysis process based on the Fourier algorithm can provide data support for the intelligent management of the power supply system and improve the intelligence level of the system; combining the advantages of the Hall sensor and the Fourier algorithm, it provides new ideas and methods for the development of leakage detection technology.

[0104] Example 5: Figure 5 As shown, based on Example 4, the process of decomposing the amplitude and phase information of each harmonic provided in the embodiment of the present invention includes the following steps:

[0105] S2021: The preprocessed current signal is input into Fourier transform to convert the time domain signal into a frequency domain signal to obtain different frequency components contained in the current signal;

[0106] S2022: performing an integration operation on the current signal, and extracting the amplitude and phase information of each frequency component in the current signal by performing inner product with sine and cosine functions of different frequencies;

[0107] S2023: In the Fourier transform result, each frequency point corresponds to a complex value. The modulus of the complex value represents the amplitude of the frequency component, and the phase angle represents the phase of the frequency component, thereby decomposing the amplitude and phase of each harmonic in the current signal.

[0108] The working principle and beneficial effects of the above technical solution are as follows: In this embodiment, the pre-processed current signal is first input into the Fourier transform, and the time domain signal is converted into a frequency domain signal to obtain different frequency components contained in the current signal; secondly, the current signal is integrated, and the amplitude and phase information of each frequency component in the current signal are extracted by performing inner product with sine and cosine functions of different frequencies; finally, each frequency point in the Fourier transform result corresponds to a complex value, the modulus of the complex value represents the amplitude of the frequency component, and the phase angle represents the phase of the frequency component, and the amplitude and phase of each harmonic in the current signal are decomposed. Step S2021 of the above scheme is the conversion from time domain to frequency domain. Through Fourier transform, the current signal in the time domain is converted into a frequency domain signal; the conversion enables the frequency components of the signal to be clearly presented, which is convenient for the analysis and processing of each harmonic. Significance: Time domain signals usually contain complex waveforms and transient changes, and direct analysis is difficult; through Fourier transform, the signal is decomposed into components of different frequencies, so that the characteristics of each harmonic can be highlighted, laying the foundation for the accurate extraction of amplitude and phase information. Step S2022: Integral operation and inner product extraction. Integrate the current signal and extract the amplitude and phase information of each frequency component by performing inner products with sine and cosine functions of different frequencies. This achieves accurate separation of the frequency components of the signal. Significance: Integral operation and inner product operation are the core mathematical means of Fourier transform, which can effectively extract the amplitude and phase of each frequency component in the signal. Through this step, the frequency characteristics of the signal are accurately captured, providing reliable data support for harmonic analysis. Step S2023: Complex value decomposition and information extraction. In the result of Fourier transform, each frequency point corresponds to a complex value. The modulus of the complex value represents the amplitude of the frequency component, while the phase angle represents its phase. Through this step, the amplitude and phase of each harmonic in the current signal are accurately decomposed. Significance: The decomposition of complex values ​​is the ultimate goal of Fourier transform, which directly provides the amplitude and phase information of each harmonic. This information is the key basis for judging whether there is leakage in the power supply system, and is also the basic data for calculating the insulation resistance value. It realizes a comprehensive analysis of the frequency characteristics of the current signal, and provides accurate technical support for leakage detection and insulation resistance calculation.

[0109] In summary, this embodiment together constitutes the complete process of Fourier transform in decomposing the amplitude and phase information of each harmonic. From the conversion from time domain to frequency domain, to the accurate extraction of frequency components, to the decomposition and information extraction of complex values, it not only realizes the comprehensive analysis of the frequency characteristics of the current signal, but also provides a solid technical foundation for leakage detection and insulation resistance calculation.

[0110] Example 6: Figure 6 As shown, based on Example 5, the process of extracting the amplitude and phase information of each frequency component in the current signal provided by the embodiment of the present invention includes the following steps:

[0111] S20221: Use discrete Fourier transform to calculate the inner product of the current signal and the complex exponential function of different frequencies; the current signal is decomposed into sine and cosine components of different frequencies, and the frequency domain signal is decomposed into complex values;

[0112]

[0113] Where F[k] represents the frequency domain signal with frequency index k, which means the frequency is components; f[n] represents the value of the time domain signal at time index n; N represents the total number of sampling points of the current signal; k represents the frequency index, and its value range is 0≤k≤N-1; represents a complex exponential function, which means the frequency is The current signal f[n] is decomposed into sine and cosine components of different frequencies.

[0114] F[k] is a complex number, expressed as:

[0115] F[k]=A[k]+jB[k]

[0116] In the formula, A[k] represents the real part, which means the frequency is The amplitude of the cosine component of; B[k] represents the imaginary part, which means the frequency is The amplitude of the sinusoidal component of ; j represents the imaginary unit;

[0117] S20222: Calculate the amplitude and phase of the frequency component using complex values;

[0118] Amplitude calculation:

[0119]

[0120] In the formula, |F[k]| represents the frequency The amplitude of the component;

[0121] Phase calculation:

[0122]

[0123] In the formula, φ[k] represents the frequency The phase of the component of is in radians; arctan represents the inverse tangent function, which is used to calculate the phase angle;

[0124] S20223: For each harmonic in the current signal, extract its amplitude and phase by calculating a specific frequency point;

[0125] For the nth harmonic, its frequency is ω n =nω0, where ω0 is the fundamental frequency and the frequency index is

[0126]

[0127] In the formula, k n represents the frequency index of the nth harmonic; P represents the number of cycles of the signal; by calculating Fk n , we can get the amplitude Fk of the nth harmonic n and phase φ[k n ].

[0128] The working principle and beneficial effects of the above technical solution are as follows: This embodiment first uses discrete Fourier transform to calculate the inner product of the current signal and the complex exponential function of different frequencies; the current signal is decomposed into sine and cosine components of different frequencies, and the frequency domain signal is decomposed by complex value; secondly, the amplitude and phase of the frequency component are calculated by complex value; finally, for each harmonic in the current signal, its amplitude and phase are extracted by calculating the specific frequency point. Step S20221 of the above scheme uses discrete Fourier transform to decompose the current signal into sine and cosine components of different frequencies; the time domain signal is converted into a frequency domain signal, so that the frequency characteristics of the signal can be clearly presented. Its significance lies in that through this decomposition, the frequency components of the signal can be analyzed more intuitively, thereby providing a basis for frequency domain analysis, filtering, denoising and other operations. Step S20222 calculates the amplitude and phase of the frequency component through the real and imaginary parts of the complex value, and quantifies the intensity (amplitude) and phase information of each frequency component. Its significance lies in that the amplitude reflects the energy distribution of the signal at a specific frequency, while the phase reveals the time offset or phase relationship of the signal at different frequency components; this information is crucial for accurate reconstruction of the signal, harmonic analysis, and evaluation of system response. Step S20223 extracts the characteristics of each harmonic in the current signal by calculating the amplitude and phase at a specific frequency point, thereby achieving accurate extraction and analysis of specific frequency components. Its significance lies in that harmonic analysis is the core means of tasks such as detecting nonlinear loads, evaluating power quality, and diagnosing equipment failures in power systems. By extracting the amplitude and phase of harmonics, we can gain an in-depth understanding of the operating status of the system and provide data support for optimization and improvement.

[0129] In summary, this embodiment extracts key information such as frequency, amplitude and phase from time domain signals, providing a solid foundation for in-depth analysis and application of signals.

[0130] Example 7: Figure 7 As shown, based on Example 4, the process of determining whether there is a leakage phenomenon provided by the embodiment of the present invention includes the following steps:

[0131] S20231: Construct a mathematical model for calculating insulation resistance based on the basic principles of the circuit. The mathematical model includes parameters such as resistance, capacitance and inductance in the circuit, and combines the amplitude and phase information of the harmonic current.

[0132] S20232: Obtain a calculation formula for insulation resistance based on parameter, amplitude and phase information;

[0133] The circuit is an equivalent circuit, including insulation resistance, distributed capacitance, line resistance and load resistance; the relationship between voltage and current of the circuit is established through Kirchhoff's law and Ohm's law;

[0134] Through spectrum analysis, the harmonic current amplitude I at a specific frequency is extracted harmonic ;

[0135] According to the circuit model, the relationship between the amplitude of the harmonic current and the insulation resistance is expressed as:

[0136]

[0137] Among them, V harmonic is the harmonic voltage, Z total is the total impedance of the circuit;

[0138] Phase of harmonic current φ harmonic Reflect the characteristics of capacitance and inductance in the circuit; further verify the accuracy of the calculation results through phase information;

[0139] Combining the circuit model and the above analysis, the expression of insulation resistance is derived:

[0140]

[0141] Among them, R line is the line resistance, R load is the load resistance, R load Indicates the amplitude of harmonic current φ harmonic Indicates the phase of harmonic current;

[0142] S20233: After calculating the insulation resistance value, compare it with the preset safety threshold to determine whether there is leakage;

[0143] If R insulation <R threshold , it is determined that there is leakage; R threshold Indicates the safety threshold;

[0144] If R insulation≥ R threshold , it is judged as normal state.

[0145] The working principle and beneficial effects of the above technical solution are as follows: This embodiment first constructs a mathematical model for calculating insulation resistance based on the basic principle of the circuit, and the mathematical model adds parameters such as resistance, capacitance and inductance in the circuit, and combines the amplitude and phase information of the harmonic current; secondly, based on the parameters, amplitude and phase information, the calculation formula of the insulation resistance is obtained; finally, after the insulation resistance value is calculated, it is compared with the preset safety threshold to determine whether there is leakage; Step S20231 of the above scheme constructs a mathematical model for calculating insulation resistance, and by introducing parameters such as resistance, capacitance and inductance in the circuit, an equivalent circuit model is constructed, which can fully reflect the electrical characteristics of the circuit; combined with the amplitude and phase information of the harmonic current, the nonlinear characteristics in the circuit can be analyzed more accurately, especially in the presence of harmonic interference. The significance achieved: Through the mathematical model, the electrical behavior of the circuit can be accurately described, which provides a solid foundation for calculation and analysis; the model takes into account a variety of parameters in the circuit, which can fully reflect the complexity of the circuit and improve the accuracy and reliability of the analysis. Step S20232 obtains the calculation formula of insulation resistance. Through Kirchhoff's law and Ohm's law, the voltage and current relationship of the circuit is established, and the expression of insulation resistance is derived; the harmonic current amplitude and phase information at a specific frequency are extracted through spectrum analysis, and the accuracy of the calculation result is further verified. The significance achieved: through formula derivation, complex circuit characteristics can be quantified into specific mathematical expressions, which is convenient for calculation and analysis; through spectrum analysis and phase information, the accuracy of the calculation result can be verified to ensure the reliability of the analysis. Step S20233 compares with the preset safety threshold. By comparing the calculated insulation resistance value with the preset safety threshold, it can quickly determine whether there is leakage; by setting the threshold, automatic judgment is achieved, and the efficiency and accuracy of detection are improved. The significance achieved: by comparing with the safety threshold, leakage can be discovered and handled in time to ensure the safe operation of the circuit; the automation of leakage detection is realized, manual intervention is reduced, and work efficiency and reliability are improved.

[0146] In summary, this embodiment not only realizes comprehensive analysis and quantitative calculation of circuit characteristics, but also can timely discover and handle leakage phenomena through automated judgment, thereby ensuring safe operation of the circuit and improving work efficiency and reliability.

[0147] Example 8: Figure 8 As shown, based on Example 1, the process of quickly judging the leakage value and area and judging the alarm protection provided by the embodiment of the present invention includes the following steps:

[0148] S301: Locate the specific area where leakage occurs based on the distribution and change trend of the current, combined with the actual layout of the coal mine and the topological structure geographical information of the power supply system;

[0149] S302: When leakage is detected, an alarm mechanism is triggered to notify relevant personnel to handle the problem. The alarm information includes the amplitude, occurrence time and specific location of the leakage current. At the same time, the harmonic current is dynamically monitored to protect specific areas or equipment from leakage.

[0150] S303: Record the result of each leakage detection, including the characteristics of the leakage current, positioning information and processing results.

[0151] The working principle and beneficial effects of the above technical solution are as follows: the present embodiment first locates the specific area where leakage occurs according to the distribution and change trend of the current, combined with the actual layout of the coal mine and the topological structure of the power supply system; secondly, the leakage phenomenon is detected, the alarm mechanism is triggered, and the relevant personnel are notified to handle it; the alarm information includes the amplitude, occurrence time and specific location of the leakage current; at the same time, the harmonic current is dynamically monitored to protect the leakage of specific areas or equipment; finally, the results of each leakage detection are recorded, including the characteristics of the leakage current, positioning information and processing results. Step S301 of the above scheme can accurately locate the specific area where leakage occurs by analyzing the distribution and change trend of the current, combined with the actual layout of the coal mine and the topological structure of the power supply system; this positioning not only depends on the current data, but also combines the geographical information to ensure the accuracy of positioning; it can analyze the current data in real time, quickly identify the leakage phenomenon, and immediately locate the leakage area, providing timely information support for alarm and processing. Significance achieved: Accurate regional positioning can greatly shorten the time of troubleshooting, reduce shutdowns and safety hazards caused by leakage, and improve the production efficiency of coal mines; by combining geographic information and power supply system topology, it can avoid misjudgment, ensure that each alarm is based on accurate leakage detection results, and reduce unnecessary maintenance and shutdowns. Step S302 Triggering the alarm mechanism and dynamic monitoring Once the leakage phenomenon is detected, the system immediately triggers the alarm mechanism and notifies the relevant personnel to handle it. The alarm information includes the amplitude, occurrence time and specific location of the leakage current to ensure that the relevant personnel can respond quickly; while the alarm is issued, the system dynamically monitors the harmonic current to ensure that it can continue to provide protection before the leakage problem is solved; dynamic monitoring can also realize selective leakage protection, that is, only protect the leakage of specific areas or equipment to avoid false operation. Significance achieved: The timely alarm mechanism can ensure that when leakage occurs, the relevant personnel can take measures quickly to avoid electric shock accidents caused by leakage and ensure personnel safety; dynamic monitoring and selective protection can effectively reduce equipment damage caused by leakage, extend the service life of equipment, and reduce maintenance costs. Step S303 records the leakage detection results, and records the results of each leakage detection, including the characteristics of the leakage current, location information and processing results; these data can be used for subsequent analysis and optimization to improve the detection accuracy and response speed of the system; through the analysis of historical data, potential failure modes can be discovered, preventive maintenance can be carried out in advance, and the occurrence of sudden failures can be reduced. Significance achieved: Through data accumulation and analysis, the detection algorithm and response mechanism can be continuously optimized, the intelligence level of the system can be improved, and it can adapt to different working environments and conditions; the analysis of historical data can help coal mine managers discover potential failure risks in advance, carry out preventive maintenance, and reduce downtime and production losses caused by failures.

[0152] In summary, this embodiment can not only quickly and accurately determine the leakage value and area, but also timely alarm, dynamic monitoring and data recording, thereby improving the safety and reliability of the coal mine underground power supply system. The comprehensive application of these steps not only improves the efficiency of fault handling, but also ensures the safety of personnel and equipment, providing strong technical support for coal mine production.

[0153] Example 9: Fig. 9 As shown, based on Example 8, the process of locating the specific area where leakage occurs provided by the embodiment of the present invention includes the following steps:

[0154] S3011: Matching the monitoring point of the current anomaly with the physical position in the underground layout. The current anomaly appears at the monitoring point of a power supply line. According to the geographic information of the underground layout, the actual physical position corresponding to the monitoring point is determined, such as a certain lane or a certain working face;

[0155] S3012: Analyze the propagation path of the abnormal current by using the topology of the power supply system; the topology describes the connection relationship between various devices and lines in the power supply system. By analyzing the propagation path of the abnormal current, the source of the abnormal current is determined; if the abnormal current occurs on a main power supply line, further trace the branch of the line to analyze whether the abnormal current is caused by a branch line or a device;

[0156] S3013: After completing the matching of the current abnormality area with the geographic information of the underground layout and the current path analysis in the topological structure, information fusion is performed; the area of ​​current abnormality is combined with the geographic information of the underground layout and the topological structure of the power supply system to form a comprehensive positioning model; it is determined that the current abnormality occurs on a specific power supply branch or on a specific device.

[0157] The working principle and beneficial effects of the above technical solution are as follows: In this embodiment, the monitoring point of the current anomaly is first matched with the physical position in the underground layout. The current anomaly occurs at the monitoring point of a power supply line. According to the geographic information of the underground layout, the actual physical position corresponding to the monitoring point is determined, such as a tunnel or a working face; secondly, the propagation path of the current anomaly is analyzed by using the topological structure of the power supply system; the topological structure describes the connection relationship between each device and line in the power supply system, and the source of the current anomaly is determined by analyzing the propagation path of the current anomaly; if the current anomaly occurs on a main power supply line, the branch of the line is further traced to analyze whether the current anomaly is caused by a branch line or a certain device; finally, after completing the matching of the current anomaly area with the geographic information of the underground layout and the current path analysis in the topological structure, information fusion is performed; the area of ​​the current anomaly is combined with the geographic information of the underground layout and the topological structure of the power supply system to form a comprehensive positioning model; it is determined that the current anomaly occurs on a specific power supply branch or on a specific device. In step S3011 of the above scheme, the monitoring point of the current anomaly is matched with the physical position in the underground layout. By matching the monitoring point of the current anomaly with the geographic information of the underground layout, the abstract current data can be converted into a specific physical position, such as a certain lane or a certain working face; so that the specific position of the current anomaly can be located in real time, providing basic data for analysis and processing. Significance achieved: By quickly locating the physical position of the current anomaly, the time for troubleshooting can be greatly shortened, and production interruptions caused by leakage can be reduced; accurate positioning helps to take measures in time to prevent safety accidents caused by leakage and protect the lives of underground workers. Step S3012 uses the topological structure of the power supply system to analyze the propagation path of the current anomaly. By analyzing the topological structure of the power supply system, the propagation path of the current anomaly can be traced and the source of the anomaly can be determined, such as a branch line or a certain device; it can help identify the specific source of the current anomaly, whether it is a line problem or a device failure. Significance achieved: Through path analysis, the fault source can be accurately identified, unnecessary inspections of the entire power supply system can be avoided, and the efficiency of fault handling can be improved; understanding the propagation path of the current anomaly helps to formulate more effective maintenance strategies and prevent similar problems from happening again. Step S3013: Information fusion forms a comprehensive positioning model, combining the area of ​​current anomaly with the geographic information of the underground layout and the topological structure of the power supply system to form a comprehensive positioning model to ensure the accuracy and comprehensiveness of positioning; through information fusion, the positioning model can be continuously optimized to improve its adaptability to complex environments. Significance achieved: Comprehensive analysis can improve the accuracy of positioning and ensure that every fault can be accurately located and handled; by continuously optimizing the positioning model, the reliability of the entire monitoring system can be enhanced to ensure that it can work effectively in various complex environments.

[0158] In summary, step S3011 of this embodiment provides basic geographic information, step S3012 determines the fault source through path analysis, and step S3013 improves the accuracy and reliability of positioning through information fusion. Together, they form an efficient and accurate leakage positioning system, which not only improves the efficiency of fault handling, but also enhances the safety and reliability of underground operations.

[0159] Example 10: Fig.10 As shown, based on Example 9, the process of forming a comprehensive positioning model provided by the embodiment of the present invention includes the following steps:

[0160] S30131: Based on the fused information data, design a comprehensive positioning model framework, including input layer, processing layer and output layer; the input layer receives geographic information, topological structure and current anomaly data; the processing layer performs data analysis and feature extraction; the output layer generates the positioning results of current anomalies;

[0161] S30132: In the processing layer, feature extraction is performed on the input information data. The extracted features include the intensity of the current anomaly, the propagation path, the working status of the equipment, etc.; the propagation path of the current anomaly is analyzed by using the topological structure; the source and propagation direction of the current anomaly are determined through path analysis; if the current anomaly appears on a main power supply line, the branch of the line is traced to analyze whether the current anomaly is caused by a branch line or a certain device;

[0162] S30133: Based on the results of feature extraction and path analysis, positioning calculation is performed, and the specific location of the current anomaly is determined by the positioning algorithm based on the topological structure; the result of the positioning calculation is output to the result output layer, and the output result is a specific physical location, such as a lane or a working face; it is presented in the form of a graphic.

[0163] The working principle and beneficial effects of the above technical solution are as follows: First, based on the fused information data, this embodiment designs a comprehensive positioning model framework, including an input layer, a processing layer and an output layer; the input layer receives geographic information, topological structure and current anomaly data; the processing layer performs data analysis and feature extraction; the output layer generates the positioning result of the current anomaly; secondly, in the processing layer, feature extraction is performed on the input information data, and the extracted features include the intensity of the current anomaly, the propagation path, the working status of the equipment, etc.; the topological structure is used to analyze the propagation path of the current anomaly; the source and propagation direction of the current anomaly are determined through path analysis; if the current anomaly appears on a main power supply line, the branch of the line is traced to analyze whether the current anomaly is caused by a branch line or a certain device; finally, based on the results of feature extraction and path analysis, positioning calculation is performed, and the specific location of the current anomaly is determined by the positioning algorithm based on the topological structure; the result of the positioning calculation is output to the result output layer, and the output result is a specific physical location, such as a lane or a working face; it is presented in the form of a graphic. Step S30131 of the above scheme designs a comprehensive positioning model framework. By clearly dividing the input layer, processing layer and output layer, the model structure is clear and easy to maintain and upgrade; the input layer receives a variety of data (geographic information, topological structure, current anomaly data), which enhances the data processing capability and adaptability of the model. The significance achieved: It provides a systematic framework for data analysis and feature extraction to ensure the coherence and consistency of data processing; through the fusion of multi-source data, it can more comprehensively analyze current anomalies, thereby improving the accuracy of positioning. Step S30132 feature extraction and path analysis, extract key features such as the intensity, propagation path, and device status of current anomalies, and provide data support for positioning calculations; using the topological structure to analyze the propagation path of current anomalies, it can track the source and propagation direction of anomalies, which helps to quickly locate problems. The significance achieved: Through feature extraction and path analysis, the source of current anomalies can be accurately identified, reducing misjudgments and missed judgments; path analysis helps to quickly locate problems, shortens troubleshooting time, and improves the response speed of the system. Step S30133 Positioning calculation and result output, based on the positioning algorithm of the topological structure, can accurately calculate the specific location of the current anomaly; present the positioning results in graphical form for intuitive understanding and operation. The significance achieved is that through positioning calculation, it can be accurate to the specific physical location (such as a lane or a working surface), providing clear guidance for maintenance and processing; the graphical presentation of the results is convenient for operators to quickly understand and execute, thereby improving work efficiency.

[0164] In summary, this embodiment achieves accurate positioning and rapid response to current anomalies through modular design, feature extraction, path analysis and positioning calculation. Each step together constitutes an efficient and reliable positioning system, which provides a strong guarantee for the stable operation of the power system.

[0165] Example 11: Fig.11 As shown, on the basis of Embodiment 1 to Embodiment 9, the 3DR leakage detection protection method for underground coal mines provided by the embodiment of the present invention is composed of a 3DR leakage detection module 1, an MCU processor 2, a bridge-type additional DC detection module 3, an automatic switching module 4, a dynamic correction module 5 and a distributed capacitance detection module 6;

[0166] Among them, the input end of the 3DR leakage detection module 1 is connected to the power supply system of the transformer substation, the voltage of the power supply system of the transformer substation is AC10000V, 6000V, 3300V, 1905V, 1140V and 660V, etc., and the 3DR leakage detection module 1 includes a diode, a probe and a resistor, etc.; the 3DR leakage detection module 1 is connected to the Vdc interface of the MCU processor 2, the Rs interface and the PE end of the MCU processor 2 are connected to the bridge-type additional DC detection module 3, and the input end of the bridge-type additional DC detection module 3 is AC100V; the Udc interface of the MCU processor 2 is connected to the input end of the automatic switching module 4, and the automatic switching module 4 is connected to the input end of the 3DR leakage detection module 1 and the dynamic correction module 5; the 3Io interface of the MCU processor 2 is connected to the 3Io interface of the dynamic correction module 5, the Isy interface of the MCU processor 2 is connected to the distributed capacitance detection module 6, the distributed capacitance detection module 6 is connected to one end of the Rsy test resistor and the dynamic correction module 5, and 6 is connected to the other end of the Rsy test resistor The ground terminal;

[0167] The 3DR leakage detection module 1 of this embodiment uses the voltage of the power supply system of the transformer substation to establish an auxiliary star point through a three-phase half-wave, and detects the carrier component and fundamental component through the Udc voltage of the auxiliary star point, and detects the waveform of the residual leakage current through the AC / DC Hall current sensor; the MCU processor 2 analyzes the harmonics through the Fourier series to realize leakage detection and protection and performs the Fourier algorithm to obtain the leakage value; the bridge-type additional DC detection module 3 is used for leakage lockout, which automatically corrects the 3DR leakage detection parameters during the detection; the automatic switching module 4 performs leakage lockout and automatic switching of leakage according to the presence or absence of three-phase voltage; the dynamic correction module 5 performs dynamic correction of the 3DR leakage detection of the three-phase zero-sequence detection of harmonic leakage current and fundamental leakage current; the distributed capacitance detection of the distributed capacitance detection module 6 is based on the test current transformer. The distributed capacitance amplitude is detected by the MCU processor 2, and the 3DR leakage detection is manually corrected. Based on 3DR technology, leakage detection of 6-pulse and 12-pulse inverters can be realized; based on 3DR technology, insulation detection of different voltage levels of IT power supply systems can be realized; based on fundamental frequency, detection of system distributed capacitance can be realized.

[0168] The working principle and beneficial effects of the above technical solution are as follows: the 3DR leakage detection module 1 of this embodiment is connected to the power supply system of the transformer substation to monitor circuits of different voltage levels (such as AC10000V, 6000V, 3300V, etc.); the auxiliary star point is established by using the three-phase half-wave, and the carrier component and the fundamental component are detected by the Udc voltage of the auxiliary star point; the waveform of the residual leakage current is detected by the AC / DC Hall current sensor. The MCU processor 2 analyzes the harmonics through the Fourier series to achieve leakage detection and protection; the leakage value is obtained by using the Fourier algorithm and dynamically corrected. The bridge-type additional DC detection module 3 is used for leakage lockout and automatically corrects the 3DR leakage detection parameters. The automatic switching module 4 automatically switches the leakage lockout and leakage detection according to the presence or absence of the three-phase voltage. The dynamic correction module 5 dynamically corrects the harmonic leakage current and the fundamental leakage current of the three-phase zero-sequence detection. The distributed capacitance detection module 6 detects the distributed capacitance amplitude based on the test current transformer and manually corrects it through the MCU processor 2.

[0169] This embodiment can accurately detect leakage values ​​and improve detection accuracy through Fourier series and harmonic analysis; the dynamic correction module can adjust detection parameters in real time to adapt to different working conditions and ensure the stability and reliability of detection; the automatic switching module can automatically adjust the detection mode according to the voltage conditions, simplify the operation, and improve the intelligence level of the system; the distributed capacitance detection module can detect the distributed capacitance in the system, help identify potential leakage risks, and improve the safety of the system. Based on 3DR technology, the system can adapt to IT power supply systems of different voltage levels, realize leakage detection of 6-pulse and 12-pulse inverters, and has a wide range of applicability; it can monitor and protect in real time, timely discover and deal with leakage problems, and ensure safe operation underground in coal mines. It realizes functions such as high precision, dynamic correction, automatic switching and distributed capacitance detection, effectively improving the electrical safety level underground in coal mines.

[0170] Example 12: Fig.12 As shown, on the basis of Example 11, the principle diagram of 6-pulse frequency converter 3DR leakage detection of the power supply system of the dynamic converter substation in the coal mine provided by the embodiment of the present invention comprises: a converter substation 7, a 3DR leakage detection module 1, a harmonic current detection module 8, a rectifier 9, an inverter 10 and a motor 11;

[0171] Among them, the converter substation 7 is connected to the 3DR leakage detection module 1, the 3DR leakage detection module 1 is connected to the harmonic current detection module 8, the harmonic current detection module 8 is connected to the rectifier 9, the rectifier 9 is connected to the inverter 10, and the inverter 10 is connected to the motor 11;

[0172] The working principle and beneficial effects of the above technical solution are as follows: The converter substation 7 of this embodiment is the core part of the underground power supply system of the coal mine, which is mainly responsible for converting high voltage electricity into low voltage electricity suitable for underground equipment; converting high voltage AC into low voltage DC through transformers and rectifiers to provide stable power supply for subsequent frequency converters and motors; ensuring the safe operation of underground equipment and improving the stability and efficiency of the power supply system. The 3DR leakage detection module 1 is used to detect leakage in the circuit to prevent electrical accidents caused by leakage; judging whether there is leakage by detecting the current imbalance in the circuit, once leakage is detected, immediately cut off the power supply to prevent accidents; improve the safety of the underground power supply system and effectively prevent electrical accidents. The harmonic current detection module 8 is used to detect the harmonic current in the circuit to prevent harmonics from damaging the equipment and the power grid; through filters and detection circuits, the harmonic components in the circuit are monitored in real time, and once the harmonics are found to exceed the standard, measures are taken immediately to suppress them; protect the equipment and the power grid from harmonic damage and improve the power supply quality. Rectifier 9 is a device that converts AC power into DC power, providing a stable DC power supply for the inverter; it converts AC power into DC power through components such as diodes or thyristors, eliminates voltage fluctuations, and provides a stable power supply for the inverter; ensures the stable operation of the inverter and the motor, and improves the reliability of the system. Inverter 10 is a device that converts DC power into AC power, providing an adjustable AC power supply for the motor; through power switching components such as IGBT, it converts DC power into AC power with adjustable frequency and voltage to meet the different operating requirements of the motor; it realizes stepless speed regulation of the motor and improves the operating efficiency and flexibility of the equipment. Motor 11 is the power source of underground equipment in coal mines, which drives the equipment to operate by converting electrical energy into mechanical energy; through the principle of electromagnetic induction, it converts electrical energy into mechanical energy to drive the equipment to rotate or move; it provides stable and reliable power to ensure the normal operation of underground equipment.

[0173] The converter substation 7 of this embodiment is connected to the 3DR leakage detection module 1 to ensure the safety of the power supply system; the 3DR leakage detection module 1 is connected to the harmonic current detection module 8 to monitor the leakage and harmonic conditions in the circuit in real time; the harmonic current detection module 8 is connected to the rectifier 9 to ensure the power quality at the input end of the rectifier; the rectifier 9 is connected to the inverter 10 to provide a stable DC power supply for the inverter; the inverter 10 is connected to the motor 11 to provide an adjustable AC power supply for the motor to drive the equipment to operate. Through the organic combination of the above structures, the entire system can achieve efficient, safe and stable power supply to ensure the safe operation of coal mine underground equipment. By implementing leakage protection for the mobile 6-pulse inverter, the fundamental component, carrier frequency, harmonic component and other data in the system voltage are detected, and the system leakage protection is performed by entering the MCU processor through the 3DR leakage detection channel.

[0174] Example 13: Fig.13As shown, on the basis of Example 11, the embodiment of the present invention provides a coal mine underground mobile converter substation inverter power supply system 12-pulse 3DR leakage detection, comprising: a high-voltage switch 12, a 12-pulse mobile converter substation 13, a 3DR leakage detection module 1, a harmonic current detection module 8, a VFD inverter 14, and a motor 11;

[0175] Among them, the high-voltage switch 12 is connected to the 12-pulse mobile converter substation 13, the 12-pulse mobile converter substation 13 is connected to the 3DR leakage detection module 1, the 3DR leakage detection module 1 is connected to the harmonic current detection module 8, the harmonic current detection module 8 is connected to the VFD inverter 14, and the VFD inverter 14 is connected to the motor 11.

[0176] The working principle and beneficial effects of the above technical solution are as follows: the high-voltage switch 12 is responsible for controlling the access and disconnection of high-voltage electricity as the entrance of the system to ensure the safe operation of the system; the 12-pulse mobile converter substation 13 converts high-voltage AC into low-voltage DC through 12-pulse rectification technology, reduces harmonic pollution and improves power quality; the 12-pulse rectification uses the parallel connection of two 6-pulse rectifier bridges to achieve mutual cancellation of harmonics by using the phase difference, thereby reducing the harmonic content. The 3DR leakage detection module 1 monitors the leakage of the system in real time by detecting the leakage current in the circuit; the 3DR leakage detection module 1 can capture the leakage signal more accurately through three-phase detection to ensure the safe operation of the system. The harmonic current detection module 8 is used to detect the harmonic current in the system, especially the harmonics generated by the frequency converter; by detecting the harmonic current, the power quality of the system can be monitored in real time, and data support can be provided for subsequent harmonic suppression. The VFD frequency converter 14 achieves precise control of the motor 11 by adjusting the output frequency and voltage. The frequency converter will generate harmonics during operation, and the harmonic current detection module 8 can monitor these harmonics in real time to ensure the stable operation of the system. The motor 11 is the final load device, and the speed is adjusted by the frequency converter to meet the needs of different working conditions in coal mines.

[0177] This embodiment can effectively reduce harmonic pollution and improve power quality through 12-pulse rectification technology. 12-pulse rectification uses the phase difference to achieve mutual cancellation of harmonics through the parallel connection of two groups of 6-pulse rectifier bridges, thereby reducing the harmonic content and ensuring the stability and reliability of the power supply system. The 3DR leakage detection module 1 can capture the leakage signal more accurately through three-phase detection to ensure the safe operation of the system. When leakage is detected, the system can quickly cut off the power supply to avoid accidents. The harmonic current detection module 8 monitors the harmonic current in the system in real time, especially the harmonics generated by the frequency converter; by detecting the harmonic current, the power quality of the system can be monitored in real time, and data support can be provided for subsequent harmonic suppression to ensure the stable operation of the system. The VFD inverter 14 achieves precise control of the motor 11 by adjusting the output frequency and voltage to meet the needs of different working conditions in coal mines; the use of the inverter not only improves the operating efficiency of the motor, but also reduces energy consumption. Through the control of the high-voltage switch 12, the power supply can be quickly cut off when necessary to ensure the safety of the system; at the same time, the real-time monitoring of the 3DR leakage detection module 1 further improves the safety performance of the system. It can adapt to the complex and changeable working conditions in coal mines and ensure stable operation in various environments.

[0178] In summary, the 12-pulse 3DR leakage detection technical solution for the mobile substation inverter power supply system in the coal mine underground of this embodiment ensures the safe, stable and efficient operation of the system through multiple detection and protection mechanisms, and provides reliable power guarantee for the production in the coal mine underground. It uses the three-phase half-wave of the substation power supply system to build a common auxiliary star point connected to the dual voltage system through common cathode and common anode wiring; by detecting the harmonic components flowing through R, the fundamental wave component, carrier frequency, harmonic component and other data of the system voltage are realized. In view of the dual voltage power supply, the dual 3DR leakage detection channel is used to merge and build the auxiliary star point to enter the MCU processor to protect the system leakage.

[0179] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention belong to the scope of equivalent technologies of the present invention, the present invention is also intended to include these modifications and variations.

Claims

1. A 3DR leakage detection and protection method for underground coal mines, characterized in that: The following steps are involved: Using the three-phase half-wave of the power supply system of the transformer substation, an auxiliary star point connected to the power supply system of the transformer substation is constructed through common cathode or common anode wiring; The residual current Hall sensor is used to detect the residual current of different harmonics, and the 3DR leakage current measurement insulation resistance technology is identified based on the Fourier algorithm; According to the harmonic components, the leakage resistance of the inverter of the coal mine mobile converter substation power supply system is realized, the leakage value and area are quickly judged, and the judgment alarm protection is carried out; and the harmonic current is dynamically detected to realize selective leakage protection.

2. The 3DR leakage detection and protection method for underground coal mines according to claim 1, characterized in that: The process of building an auxiliary star point connected to the power supply system of the transformer substation includes the following steps: The three-phase voltage is rectified by a three-phase half-wave rectifier circuit, which is composed of three groups of diodes, corresponding to the positive or negative half cycle of the three-phase voltage respectively; in the three-phase half-wave rectifier circuit, the diodes use a common cathode or common anode connection method to convert the three-phase voltage into a DC voltage, and at the same time form an auxiliary star point; After the voltage of the power supply system of the transformer substation is rectified, a DC voltage is formed at the auxiliary star point, and the DC voltage is filtered; the DC voltage is the average value of the three-phase voltage, reflecting the overall voltage level of the power supply system of the transformer substation; Through Fourier transform, the DC voltage waveform is decomposed into components of different frequencies. The fundamental component corresponds to the basic frequency of the power supply system of the transformer substation, while the carrier component corresponds to the high-frequency component. The fundamental component and the carrier component are extracted respectively through the bandpass filter; the current change in the power supply system is monitored in real time through the Hall current sensor, and the waveform of the residual leakage current is extracted.

3. The 3DR leakage detection and protection method for underground coal mines according to claim 2, characterized in that: The process of decomposing the DC voltage waveform into components of different frequencies includes the following steps: Obtain a rectified and filtered DC voltage signal from the auxiliary star point, and use Fourier transform to convert the pre-processed DC voltage signal from the time domain to the frequency domain. The DC voltage signal is decomposed into components of different frequencies, each component corresponding to a specific frequency and amplitude; In the frequency domain, the DC voltage signal is decomposed into multiple frequency components, including fundamental wave component and carrier wave component; the fundamental wave component corresponds to the basic frequency of the power supply system of the DC substation and reflects the basic voltage characteristics; the carrier wave component is a high-frequency component and reflects the nonlinear characteristics; The frequency domain signal is processed using a bandpass filter to extract the fundamental component and the carrier component respectively; The Hall current sensor measures the instantaneous value of the current and decomposes the current signal into components of different frequencies through Fourier transform; By analyzing the components, the waveform of the residual leakage current is extracted.

4. The 3DR leakage detection and protection method for underground coal mines as claimed in claim 3, characterized in that: The process of identifying the 3DR leakage current measurement insulation resistance technology based on the Fourier algorithm includes the following steps: The Hall sensor collects the residual current signal in the power supply system in real time, including fundamental current and harmonic current components; The Hall sensor performs preliminary processing on the collected residual current signal to separate the harmonic currents of different frequencies; The pre-processed current signal is input into Fourier transform to decompose the amplitude and phase information of each harmonic; According to the results of Fourier transform, the amplitude and phase of each harmonic current are analyzed; Combined with the circuit parameters of the power supply system of the converter substation, the insulation resistance value in the 3DR leakage measurement is calculated; based on the calculated insulation resistance value, it is determined whether there is leakage.

5. The 3DR leakage detection and protection method for underground coal mines as claimed in claim 4, characterized in that: The process of decomposing the amplitude and phase information of each harmonic includes the following steps: The preprocessed current signal is input into Fourier transform to convert the time domain signal into a frequency domain signal and obtain different frequency components contained in the current signal; Perform an integral operation on the current signal, and extract the amplitude and phase information of each frequency component in the current signal by performing inner product with sine and cosine functions of different frequencies; In the Fourier transform result, each frequency point corresponds to a complex value. The modulus of the complex value represents the amplitude of the frequency component, and the phase angle represents the phase of the frequency component, decomposing the amplitude and phase of each harmonic in the current signal.

6. The 3DR leakage detection and protection method for underground coal mines as claimed in claim 5, characterized in that: The process of extracting the amplitude and phase information of each frequency component in the current signal includes the following steps: Using discrete Fourier transform, the inner product of the current signal and the complex exponential function of different frequencies is calculated; the current signal is decomposed into sine and cosine components of different frequencies, and the frequency domain signal is decomposed into complex values; Calculate the amplitude and phase of frequency components using complex values; For each harmonic in the current signal, its amplitude and phase are extracted by calculating the specific frequency point.

7. The 3DR leakage detection and protection method for underground coal mines according to claim 4, characterized in that: The process of determining whether there is leakage includes the following steps: A mathematical model for calculating insulation resistance is constructed based on the basic principle of the circuit. The resistance, capacitance and inductance parameters in the circuit are added to the mathematical model, and the amplitude and phase information of the harmonic current are combined; Based on the parameter, amplitude and phase information, the calculation formula of insulation resistance is obtained; After the insulation resistance value is calculated, it is compared with the preset safety threshold to determine whether there is leakage.

8. The 3DR leakage detection and protection method for underground coal mines according to claim 1, characterized in that: The process of quickly determining the leakage value and area and conducting alarm protection includes the following steps: According to the distribution and change trend of the current, combined with the actual layout of the coal mine and the topological structure of the power supply system, the specific area where the leakage occurs can be located; When leakage is detected, the alarm mechanism is triggered and relevant personnel are notified to handle the problem. The alarm information includes the amplitude, occurrence time and specific location of the leakage current. At the same time, the harmonic current is dynamically monitored to protect specific areas or equipment from leakage. Record the results of each leakage detection, including the characteristics of the leakage current, location information and processing results.

9. The 3DR leakage detection and protection method for underground coal mines as claimed in claim 8, characterized in that: The process of locating the specific area where the leakage occurs includes the following steps: The monitoring point of the current anomaly is matched with the physical location in the underground layout. The current anomaly appears at the monitoring point of a power supply line. According to the geographical information of the underground layout, the actual physical location corresponding to the monitoring point is determined; The propagation path of abnormal current is analyzed by using the topological structure of the power supply system; the topological structure describes the connection relationship between various devices and lines in the power supply system. By analyzing the propagation path of abnormal current, the source of abnormal current can be determined; After completing the matching of the current abnormality area with the geographic information of the underground layout and the current path analysis in the topological structure, information fusion is performed; the area of ​​current abnormality is combined with the geographic information of the underground layout and the topological structure of the power supply system to form a comprehensive positioning model; it is determined that the current abnormality occurs on a specific power supply branch or on a specific device.

10. The 3DR leakage detection and protection method for underground coal mines according to claim 9, characterized in that: If current anomalies occur on a main power supply line, further trace the branches of the line to analyze whether the current anomaly is caused by a branch line or a device.

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