Coal mine underground 3dr electric leakage detection protection method

Abstract

The application provides a coal mine underground 3DR electric leakage detection protection method, which comprises the following steps: an auxiliary star point connected with a system is constructed by using three-phase half waves of a mobile variable current substation power supply system through common negative or common positive wiring; a residual current Hall sensor is used to detect electric leakage residual currents of different harmonics, and a Fourier algorithm is used to distinguish the 3DR electric leakage measurement insulation resistance technology; according to harmonic components, the electric leakage resistance of a frequency converter of the mobile variable current substation power supply system of the coal mine can be realized, the electric leakage value and the area can be judged, and alarm protection can be realized; and dynamic detection of harmonic currents can be realized, and selective electric leakage protection can be realized. Through the 3DR electric leakage technology, the application realizes electric leakage detection and instantaneous protection of the frequency converter; and according to the detection of the fundamental wave component and the harmonic, selective electric leakage protection is realized; through the harmonic electric leakage current and the fundamental wave detection system distributed capacitance, electric leakage protection of power supply equipment in the coal mine power supply system and accurate judgment of the capacitance current are realized.

Description

Technical Field

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

[0002] In coal mine power supply systems, the stability and safety of the power supply system are paramount. With the expansion of fully mechanized mining faces and the widespread use of high-capacity, high-energy-consuming electrical equipment underground, energy conservation and safety must be considered. With the rapid development of frequency converter technology, frequency converters are widely used in coal mines. Their high efficiency, energy saving, variable frequency speed control, and long-distance start-up are considered one of the most ideal and promising speed control methods. However, the high-order harmonics introduced by frequency converters significantly impact the detection of three-phase-to-ground insulation resistance. Due to the unique structure and working principle of frequency converters, large harmonic components are easily generated in the system, leading to erroneous states and fault characteristics in the leakage current system of coal mines, causing significant harmonic pollution. The original zero-sequence current and zero-sequence voltage protections fail; typical additional DC leakage current detection cannot be activated due to the influence of DC components; and leakage current detection using the injection method is also affected by harmonics and carrier waves, resulting in response times that cannot meet the time requirements in coal mines. Therefore, leakage current blocking is the only viable pre-detection method. The magnitude of leakage current on the output side of a frequency converter is related to its output voltage, the insulation resistance to ground on the output side, parasitic capacitance, and the carrier frequency of its output voltage. The higher the carrier frequency, the larger the capacitance to ground, and the greater the leakage current, thus increasing the risk of electric shock. Leakage current protection is one of the three major protective measures for power supply in coal mines. If the protection does not operate correctly and sensitively, it will pose a significant potential hazard to the safety of underground workers from electric shock in the damp and harsh environment of a coal mine.

[0003] Prior art 1, application number: CN 202410638225.3, discloses a mine leakage current testing switching device. To address the problems of cumbersome operation, low efficiency, significant safety hazards, high skill requirements for operators, and reliance on manual cooperation and supervision in existing remote leakage current testing methods, the testing switching device is installed inside an explosion-proof resistor box and controlled by a CPU control module. External command signals trigger the device to complete the low-voltage leakage current test. The CPU control module receives command signals from the upper-level control system and automatically executes the leakage current test program, eliminating the need for manual operation of switches and bridging test resistors. The device can promptly detect abnormalities and take corresponding measures through the upper-level control system to eliminate safety hazards. While overcoming the limitations of traditional testing methods and completely replacing traditional remote leakage current testing methods, it can more realistically test the leakage current protection and leakage current blocking of various levels of the underground power supply system in coal mines. However, its function is relatively simple, lacking leakage current detection and protection capabilities, resulting in the need for further improvement in the safety of mine leakage current testing.

[0004] Prior art 2, application number: CN 202211403211.0, discloses a leakage current testing device and method suitable for underground power supply switches in coal mines. The device includes a remote controller for wirelessly controlling the operating modes of a remote-end leakage current testing device and a near-end leakage current testing device. The remote-end leakage current testing device is used to simulate leakage current in the cable under test or the electrical equipment near the device under test in the operating mode controlled by the remote controller; wherein the cable under test is the connecting cable between the power supply switch and the electrical equipment. The near-end leakage current testing device is used to simulate leakage current in the cable under test near the power supply switch in the operating mode controlled by the remote controller, and to control the power supply switch to close or reset in the same operating mode. Although it can detect the sensitivity and reliability of the power supply switch protection action when there is leakage current in cables or electrical equipment at different locations without being near the power supply switch, the use of wireless control results in a slower response speed for leakage current detection, which to some extent affects safety.

[0005] Prior art three, application number CN202211282407.9, discloses a leakage current protection test system for low-voltage power grids in mines. The system includes: a power distribution cabinet, a high-voltage leakage current test cabinet, a main power supply test cabinet, a branch power supply test cabinet, the protected device under test, the main power supply switch under test, and the branch power supply switch under test. Although it can realize leakage current detection of various protected devices, main power supply switches, and branch power supply switches in mines, thereby ensuring the safety of the power system in coal mines, its structure is complex and its operation is cumbersome, increasing the cost and time of leakage current detection.

[0006] Current technologies 1, 2, and 3 all suffer from the problem that the higher the carrier frequency, the larger the capacitance to ground, and the greater the leakage current, thus increasing the risk of electric shock. Therefore, this invention provides a 3DR leakage current detection and protection method for underground coal mines. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a 3DR leakage current detection and protection method for underground coal mines, comprising the following steps:

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

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

[0010] Based on harmonic components, the leakage resistance of the frequency converter in the power supply system of the mobile converter substation in the coal mine can be quickly determined to identify the leakage value and area, and alarm protection can be performed accordingly. Furthermore, 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 converter substation includes the following steps:

[0012] The three-phase voltage is rectified by a three-phase half-wave rectifier circuit, which consists of three sets 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 are connected in a common cathode or common anode manner to convert the three-phase voltage into a DC voltage, and at the same time form an auxiliary star point.

[0013] After rectification, the voltage of the power supply system of the converter substation forms a DC voltage at the auxiliary star point. The DC voltage is then filtered. The DC voltage is the average value of the three-phase voltage and reflects the overall voltage level of the power supply system of the converter substation.

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

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

[0016] The DC voltage signal, after rectification and filtering, is obtained from the auxiliary star point. The pre-processed DC voltage signal is transformed from the time domain to the frequency domain using Fourier transform. 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 the fundamental component and the carrier component. The fundamental component corresponds to the basic frequency of the DC substation power supply system and reflects the basic voltage characteristics. The carrier component is a high-frequency component that reflects nonlinear characteristics.

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

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

[0020] The Hall sensor collects the residual current signal in the power supply system in real time, which includes 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.

[0021] The preprocessed current signal is input into the Fourier transform to decompose the amplitude and phase information of each harmonic.

[0022] Based on the Fourier transform results, 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 current measurement is calculated; based on the calculated insulation resistance value, it is determined whether there is a leakage current phenomenon.

[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 a Fourier transform to convert the time-domain signal into a frequency-domain signal, thus obtaining the different frequency components contained in the current signal.

[0025] The current signal is integrated, and the amplitude and phase information of each frequency component in the current signal are extracted by performing an inner product with sine and cosine functions of different frequencies.

[0026] In the Fourier transform, each frequency point corresponds to a complex value. The magnitude of the complex value represents the amplitude of the frequency component, while the phase angle represents the phase of the frequency component, thus 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] The Discrete Fourier Transform is used to calculate the inner product of the current signal with complex exponential functions 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.

[0029] The amplitude and phase of the frequency components are calculated using complex values.

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

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

[0032] A mathematical model for calculating insulation resistance is constructed based on the basic principles of circuits. The mathematical model incorporates the resistance, capacitance, and inductance parameters of the circuit, and combines the amplitude and phase information of harmonic currents.

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

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

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

[0036] Based on the distribution and trend of the current, combined with the actual layout of the coal mine and the topological geographical information of the power supply system, the specific area where the leakage occurred can be located.

[0037] If a leakage current is detected, an alarm mechanism is triggered to notify relevant personnel for handling. The alarm information includes the amplitude of the leakage current, the time of occurrence, and the specific location. At the same time, harmonic currents are dynamically monitored to protect against leakage current in specific areas or equipment.

[0038] Record the results of each leakage current 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 occurred includes the following steps:

[0040] The monitoring points of abnormal current are mapped to their physical locations in the underground layout. If an abnormal current occurs at a monitoring point on a certain power supply line, the actual physical location corresponding to the monitoring point is determined based on the geographical information of the underground layout.

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

[0042] After completing the matching of the current anomaly area with the geographic information of the underground layout and the analysis of the current path in the topology, information fusion is performed; the current anomaly area is combined with the geographic information of the underground layout and the topology 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.

[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 an input layer, a processing layer, and an output layer. The input layer receives geographic information, topology, and current anomaly data; the processing layer performs data analysis and feature extraction; and the output layer generates the positioning results of the current anomaly.

[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 operating status of the equipment. The propagation path of the current anomaly is analyzed using the topology. Through path analysis, the source and propagation direction of the current anomaly are determined. If the current anomaly occurs on a main power supply line, the branches of the line are traced to analyze whether the current anomaly is caused by a branch line or a certain equipment.

[0046] Based on the results of feature extraction and path analysis, a location calculation is performed, and a topology-based location algorithm determines the specific location of the current anomaly. The location calculation results are then output to the result output layer, where the output result is a specific physical location, such as a certain tunnel or working face, and presented in graphical form.

[0047] This invention is based on 3DR leakage current detection technology. It utilizes the system voltage to establish auxiliary star points through a three-phase half-wave, common cathode or common anode configuration, and uses a high-precision AC / DC Hall residual current sensor to detect the real-time resistance value of the leakage current. Based on 3DR leakage current detection technology, it achieves leakage current detection for 6-pulse and 12-pulse waves; it achieves insulation detection for different voltage levels in IT power supply systems; it achieves leakage current lockout detection for the system; based on 3DR leakage current detection technology, it utilizes a high-performance MCU, and through real-time acquisition of leakage current data, it employs Fourier series harmonic analysis combined with a dedicated algorithm to quickly (with a real-time response speed significantly superior to traditional leakage current detection methods) achieve 3DR leakage current detection and protection; and it uses the Fourier algorithm to extract the fundamental frequency to detect the distributed capacitance of the system.

[0048] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0049] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0050] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0051] Figure 1 This is a flowchart of the 3DR leakage current detection and protection method in underground coal mines according to Embodiment 1 of the present invention;

[0052] Figure 2 This is a flowchart illustrating the construction of auxiliary star points connected to the power supply system of the converter substation in Embodiment 2 of the present invention;

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

[0054] Figure 4 This is a process diagram illustrating the identification of the 3DR leakage current measurement insulation resistance technology based on the Fourier algorithm in Embodiment 4 of the present invention.

[0055] Figure 5 This is a diagram illustrating the process of extracting the amplitude and phase information of each harmonic in Embodiment 5 of the present invention.

[0056] Figure 6 This is 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 illustrating the determination of whether leakage occurs in Embodiment 7 of the present invention;

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

[0059] Figure 9 This is a process diagram illustrating the location of the specific area where leakage occurs in Embodiment 9 of the present invention;

[0060] Figure 10 This is a process diagram illustrating the formation of a comprehensive positioning model in Embodiment 10 of the present invention;

[0061] Figure 11 This is a schematic diagram of the 3DR leakage current detection and protection method in underground coal mines according to Embodiment 11 of the present invention.

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

[0063] Figure 13 This is a schematic diagram of the leakage current detection principle of the 3DR pulse frequency converter in the power supply system of the underground dynamic converter substation in a coal mine in Embodiment 13 of the present invention. Detailed Implementation

[0064] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0065] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0066] In the following description, when referring 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 this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

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

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

[0069] S200: Utilizes a residual current Hall sensor to detect residual leakage current with different harmonics, and uses a Fourier algorithm to identify the technology for measuring insulation resistance of 3DR leakage current.

[0070] S300: Based on harmonic components, it can quickly determine the leakage resistance of the frequency converter in the power supply system of the mobile converter substation in the coal mine, determine the leakage value and area, and perform judgment alarm protection; and dynamically detect harmonic current to achieve selective leakage protection.

[0071] The working principle and beneficial effects of the above technical solution are as follows: This embodiment first utilizes the three-phase half-wave power supply system of the converter substation, and constructs an auxiliary star point connected to the system through common cathode or common anode wiring; secondly, it uses a residual current Hall sensor to detect the residual current of different harmonics, and uses the Fourier algorithm to identify the 3DR leakage current measurement insulation resistance technology; finally, based on the harmonic components, it can realize the leakage resistance of the frequency converter of the coal mine mobile converter substation power supply system, quickly determine the leakage value and area, and perform judgment alarm protection; and dynamically detect the harmonic current to achieve selective leakage protection. Step S100 of the above solution constructs an auxiliary star point, using the three-phase half-wave power supply system of the converter substation, and constructs an auxiliary star point connected to the system through common cathode or common anode wiring; it can provide a stable reference point, making current detection and analysis more accurate. Significance: The construction of the auxiliary star point provides a foundation for subsequent leakage detection, ensuring the stability and reliability of the detection system; it is especially important for the complex and dangerous environment of underground coal mines, and can effectively improve the accuracy of detection and the stability of the system. Step S200 utilizes a residual current Hall sensor for detection, using the sensor to detect residual leakage current with different harmonics, and identifies the 3DR leakage current measurement insulation resistance technology based on the Fourier algorithm. This accurately detects the harmonic components of the leakage current and analyzes them using the Fourier algorithm to accurately determine the leakage situation. Significance: Through precise harmonic analysis, the specific situation of leakage can be effectively identified, including the intensity and location of the leakage; this is of great significance for timely detection and handling of leakage problems and preventing accidents. Step S300 quickly determines the leakage value and area and performs alarm protection. Based on the harmonic components, it quickly determines the leakage resistance of the frequency converter in the power supply system of the coal mine mobile converter substation and performs judgment and alarm protection; simultaneously, it dynamically detects the harmonic current to achieve selective leakage protection; it can monitor the leakage situation in real time and quickly take protective measures when an anomaly is detected. Significance: It can quickly determine the leakage current value and area and provide alarm protection, which can effectively prevent the expansion of leakage accidents and ensure the safe operation of coal mines; it can also dynamically detect harmonic current to achieve selective leakage protection, further improving the safety and reliability of the system.

[0072] This embodiment, through analysis of underground leakage protection, invents a 3DR (3D, amplitude: current magnitude, frequency: current fluctuation frequency, phase: current phase relationship; R_residual, refers to the extra current beyond the normal operating current) leakage detection and protection method for coal mines. It calculates the leakage current of the system and equipment inverters and utilizes harmonics for leakage protection. The 3DR leakage detection method is a novel leakage detection technology. It utilizes a three-phase half-wave circuit, constructing an auxiliary star point connected to the system through common cathode or common anode wiring. It uses residual current detection Hall sensors to detect the residual leakage current of harmonics in each frequency band. Based on the Fourier algorithm, it calculates the insulation resistance of the current system in real time using the 3DR leakage measurement data. This allows for rapid determination of the leakage value and area, and provides alarms and protection. This is because any periodically changing waveform can be decomposed into sinusoidal components containing the fundamental frequency and a series of harmonics that are integer multiples of the fundamental frequency. Inverter harmonics are sinusoidal components of a periodic quantity, with frequencies that are integer multiples of the fundamental frequency of 50Hz. The amplitude of the inverter harmonics and their phase relationship relative to the fundamental frequency are important factors affecting this periodic quantity. Through harmonic analysis, insulation detection of 6-pulse and 12-pulse inverters can be performed with rapid response. The 3DR leakage current protection method has greater social application potential, especially for leakage current protection in IT power supply systems.

[0073] This embodiment utilizes harmonics generated when the protected equipment leaks current for leakage current detection. It includes: leakage current detection at the grid, valve side, and output cable to motor end in a mobile converter substation based on a frequency converter power supply system; based on 3DR leakage current detection technology, using the system voltage through a three-phase half-wave, common cathode or common anode configuration to establish auxiliary star points, and using a high-precision AC / DC Hall residual current sensor to detect the real-time resistance value of the leakage current; based on 3DR leakage current detection technology, achieving leakage current detection for 6-pulse and 12-pulse waves; based on 3DR leakage current detection technology, achieving insulation detection for different voltage levels in IT power supply systems; based on 3DR leakage current detection technology, achieving leakage current lockout detection for the system; based on 3DR leakage current detection technology, using a high-performance MCU, analyzing harmonics using Fourier series based on real-time acquired leakage current data and combining it with a dedicated algorithm, achieving rapid (real-time response speed significantly better than traditional leakage current detection methods) 3DR leakage current detection and protection; and based on Fourier algorithm extraction of the fundamental frequency to achieve detection of system distributed capacitance.

[0074] This embodiment utilizes 3DR leakage current technology to achieve leakage current detection and instantaneous protection for frequency converters; it also achieves selective leakage current protection based on the detection of fundamental and harmonic components; and it enables leakage current protection and accurate judgment of capacitor current for power supply equipment in coal mine power supply systems by using harmonic leakage current and the distributed capacitance of the fundamental detection system; thus ensuring the leakage current safety protection of frequency converters and adding a leakage current protection method for neutral point ungrounded power supply systems.

[0075] In summary, this embodiment effectively improves the safety and reliability of underground power supply systems in coal mines by constructing auxiliary star points, accurately detecting harmonic currents, quickly determining leakage current values ​​and areas, and providing alarm protection. This is of great significance for ensuring the safety of coal miners and the normal operation of equipment.

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

[0077] S101: The three-phase voltage is rectified by a three-phase half-wave rectifier circuit. The three-phase half-wave rectifier circuit consists of three sets of diodes, which correspond 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 method to convert the three-phase voltage into a DC voltage and form an auxiliary star point at the same time.

[0078] 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 converter substation; the auxiliary star point provides a stable reference for voltage and current detection.

[0079] S102: After rectification, the voltage of the power supply system of the converter substation forms a DC voltage at the auxiliary star point. The DC voltage is filtered. The DC voltage is the average value of the three-phase voltage and reflects the overall voltage level of the power supply system of the converter substation.

[0080] S103: The waveform of DC voltage is decomposed into components of different frequencies through Fourier transform. The fundamental component corresponds to the basic frequency of the DC substation power supply system, while the carrier component corresponds to the high-frequency components. The fundamental component and the carrier component are extracted separately through a bandpass filter. The current change in the power supply system is monitored in real time through a Hall current sensor, and the waveform of the residual leakage current is extracted.

[0081] The working principle and beneficial effects of the above technical solution are as follows: This embodiment first rectifies the three-phase voltage through a three-phase half-wave rectifier circuit. The three-phase half-wave rectifier circuit consists of three sets of diodes, each corresponding to one of the positive or negative half-cycles of the three-phase voltage. In the three-phase half-wave rectifier circuit, the diodes use a common cathode or common anode connection to convert the three-phase voltage into a DC voltage, while simultaneously forming an auxiliary star point. 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. The auxiliary star point provides a stable reference for voltage and current detection. Secondly, the transformer... After rectification, the voltage of the power supply system of the substation forms a DC voltage at the auxiliary star point. This DC voltage is then filtered. The DC voltage is the average value of the three-phase voltages, reflecting the overall voltage level of the substation's power supply system. Finally, through Fourier transform, the waveform of the DC voltage is decomposed into components of different frequencies. The fundamental component corresponds to the fundamental frequency of the substation's power supply system, while the carrier component corresponds to high-frequency components. A bandpass filter is used to extract the fundamental and carrier components respectively. A Hall current sensor is used to monitor the current changes in the power supply system in real time and extract the waveform of the residual leakage current. Step S101 of the above scheme involves the formation of the three-phase half-wave rectifier circuit and the auxiliary star point. The three-phase AC voltage is converted to DC voltage through the three-phase half-wave rectifier circuit. The diodes in the rectifier circuit conduct during the positive half-cycle of each phase, converting the positive half-wave of the AC voltage into DC voltage. A common reference point, the auxiliary star point, is formed through a common cathode or common anode connection. The auxiliary star point is a stable reference point in the rectifier circuit and is connected to the three-phase voltage of the substation's power supply system. Significance Achieved: The auxiliary star point provides a stable reference for voltage and current detection, which is crucial for the accurate measurement and control of voltage and current in the substation. By forming the auxiliary star point, circuit design is simplified, making voltage and current detection more direct and efficient. Step S102: DC Voltage Filtering. After rectification, the substation power supply system voltage forms a DC voltage at the auxiliary star point. The DC voltage is the average of the three-phase voltages, reflecting the overall voltage level of the power supply system. Filtering the DC voltage removes the AC component, making the DC voltage smoother and more stable. Significance Achieved: The filtered DC voltage is more stable, which helps improve the stability and reliability of the power supply system. The stable DC voltage provides a more accurate reference for subsequent voltage and current detection.Step S103, Fourier Transform and Current Monitoring, decomposes the DC voltage waveform into components of different frequencies using Fourier transform. The fundamental component corresponds to the fundamental frequency of the Strain DC substation power supply system, while the carrier component corresponds to high-frequency components. A bandpass filter is used to extract the fundamental and carrier components separately, which helps analyze the frequency characteristics and high-frequency interference of the power supply system. A Hall current sensor is used to monitor current changes in the power supply system in real time and extract the waveform of residual leakage current, which helps to detect and handle current anomalies promptly. Significance: Through Fourier transform and bandpass filtering, the frequency characteristics and high-frequency interference of the power supply system can be accurately analyzed, which helps to optimize the performance of the power supply system; real-time monitoring of current changes and extraction of residual leakage current waveforms help to detect and handle current anomalies promptly, improving the safety of the power supply system.

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

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

[0084] S1031: Obtain the rectified and filtered DC voltage signal from the auxiliary star point, and use Fourier transform to convert the preprocessed 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.

[0085] The formula for the Fourier transform is:

[0086]

[0087] Combining the frequency domain differentiation characteristics, the nth derivative of a DC voltage signal is expressed in the frequency domain as:

[0088]

[0089] Further combining with the convolution theorem, the convolution of a DC voltage signal in the frequency domain can be expressed as:

[0090]

[0091] Combining the Laplace transform and the Fourier transform, the frequency domain representation of a 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, representing the amplitude and phase information of the DC voltage signal at frequency ω; x(t) represents the time domain signal, representing the input dynamic signal (such as voltage or current); jω represents the frequency component, representing the complex frequency characteristics of the DC voltage signal; Let (jω) represent the nth derivative of the time-domain signal, and let (jω) represent the dynamic characteristics of the DC voltage signal. n X(ω) represents the nth derivative of the frequency domain signal, indicating the dynamic characteristics of the DC voltage signal in the frequency domain; x(t)*h(t) represents the convolution of the time domain signal, indicating the superposition of the DC voltage signal and the system response; X(ω)·H(ω) represents the product of the frequency domain signals, indicating the result of the convolution in the frequency domain; X(s) represents the Laplace transform of the DC voltage signal, combining transient and steady-state characteristics.

[0094] S1032: 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 DC substation power supply system and reflects the basic voltage characteristics; the carrier component is a high-frequency component that reflects nonlinear characteristics.

[0095] S1033: A bandpass filter is used to process the frequency domain signal, extracting the fundamental component and the carrier component respectively; a 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.

[0096] The working principle and beneficial effects of the above technical solution are as follows: This embodiment first obtains the 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. 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 the fundamental component and the carrier component. The fundamental component corresponds to the basic frequency of the strain current substation power supply system and reflects the basic voltage characteristics. The carrier component is a high-frequency component that reflects 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 involves signal acquisition and Fourier transform. The rectified and filtered DC voltage signal is acquired from the auxiliary star points to ensure signal stability and purity, avoiding noise interference. The pre-processed DC voltage signal is then transformed from the time domain to the frequency domain using Fourier transform, decomposing the complex time-domain signal into multiple frequency components, each corresponding to a specific frequency and amplitude. The significance is that the Fourier transform decomposes the DC voltage signal into multiple frequency components, facilitating further analysis and processing; it provides a foundation for frequency domain analysis and filtering; and frequency domain analysis reveals the frequency characteristics of the signal, helping to identify the fundamental and carrier components, thus providing a better understanding of the signal's composition and variations. Step S1032 involves frequency domain decomposition and component identification. In the frequency domain, the DC voltage signal is decomposed into multiple frequency components, including the fundamental and carrier components. The fundamental component corresponds to the basic frequency of the power supply system, reflecting the basic voltage characteristics; the carrier component is a high-frequency component, reflecting nonlinear characteristics. Significance Achieved: By identifying the fundamental and carrier components, the basic and nonlinear characteristics of DC voltage signals can be analyzed in depth, helping to understand the dynamic changes and potential problems of the signal. Identifying the carrier component helps detect nonlinear components in the signal, which may indicate harmonics or faults in the system. Step S1033: Filtering and Leakage Detection. A bandpass filter is used to process the frequency domain signal, extracting the fundamental and carrier components respectively, and further analyzing the frequency characteristics of the signal. The instantaneous value of the current is measured by a Hall current sensor, and the current signal is decomposed into components of different frequencies using Fourier transform to extract the waveform of the residual leakage current. Significance Achieved: Through filtering, unwanted frequency components can be removed, retaining useful signal components, improving signal purity and analysis accuracy. Extracting the waveform of the residual leakage current helps detect insulation faults in electrical equipment or lines, promptly identifying and addressing potential safety hazards, and ensuring the safe operation of the system.

[0097] In summary, this embodiment transforms the signal from the time domain to the frequency domain using Fourier transform, decomposing it into components of different frequencies. Through filtering and component identification, it ultimately achieves 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 in Example 3, the process of identifying the 3DR leakage current measurement insulation resistance technology based on the Fourier algorithm provided in this embodiment of the invention includes the following steps:

[0099] S201: The Hall sensor collects the residual current signal in the power supply system in real time, which includes 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.

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

[0101] S203: Based on the results of the Fourier transform, analyze the amplitude and phase of each harmonic current; combine the circuit parameters of the power supply system of the converter substation to calculate the insulation resistance value in the 3DR leakage current measurement; based on the calculated insulation resistance value, determine whether there is a leakage current phenomenon.

[0102] The working principle and beneficial effects of the above technical solution 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 preprocessed current signal is input into the Fourier transform to decompose the amplitude and phase information of each harmonic; finally, based on 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 converter substation, the insulation resistance value in the 3DR leakage current measurement is calculated; based on the calculated insulation resistance value, it is determined whether there is a leakage phenomenon. Step S201 of the above solution involves real-time acquisition and preliminary processing by the Hall sensor; the Hall sensor can collect the residual current signal in the power supply system in real time, ensuring the timeliness and accuracy of the data; through preliminary processing, the fundamental current (such as 50Hz or 60Hz) and harmonic current (such as the 3rd, 5th, and 7th harmonics) can be separated, providing a clear signal basis for subsequent analysis; the Hall sensor has strong anti-interference capability and can effectively filter out environmental noise and electromagnetic interference, ensuring the purity of the signal. Significance Achieved: The separated signal provides clear frequency domain data for Fourier transform, avoiding the influence of aliasing and interference on the analysis results; by separating harmonic currents, the influence of each harmonic on insulation resistance can be analyzed more accurately, thereby improving the accuracy of leakage current detection; real-time signal acquisition and processing can promptly detect abnormalities in the power supply system, providing data support for protection actions. Step S202 Fourier Transform Analysis: Through Fourier transform, the time-domain signal is converted into a frequency-domain signal, decomposing the amplitude and phase information of each harmonic; it can simultaneously analyze the characteristics of the fundamental wave and higher harmonics, comprehensively reflecting the current distribution of the power supply system; through spectrum diagrams or harmonic analysis diagrams, the components of each harmonic are intuitively displayed, facilitating analysis and judgment. Significance Achieved: Fourier transform can reveal the distribution law of each harmonic in the power supply system, providing a scientific basis for insulation resistance calculation; through the results of Fourier transform, the amplitude and phase of each harmonic can be accurately extracted, providing accurate data input for subsequent insulation resistance calculation; Fourier transform can quickly process complex signals, significantly improving the efficiency and accuracy of data analysis. Step S203, insulation resistance calculation and leakage current judgment, combines the results of Fourier transform and the circuit parameters of the power supply system to accurately calculate the insulation resistance value in 3DR leakage current measurement; it 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, it can determine whether there is leakage current and trigger the corresponding protection action.Significance achieved: By accurately calculating insulation resistance, it is possible to more accurately determine whether there is leakage in the power supply system, avoiding 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; based on the distribution characteristics of harmonic current, selective leakage protection can be achieved, avoiding large-scale power outages or malfunctions.

[0103] In summary, this embodiment forms a complete signal processing chain, from signal acquisition and preliminary processing to Fourier transform and insulation resistance calculation, ensuring high-quality and high-precision data. By dynamically analyzing changes in harmonic current, the calculation model can be adjusted in real time, achieving accurate leakage current detection and protection. The efficiency of the Fourier algorithm and the reliability of the Hall sensor ensure rapid response and stable operation throughout the process. This embodiment, through precise leakage current detection and protection, can effectively prevent leakage accidents and ensure the safe operation of underground power supply systems in coal mines. The analysis process based on the Fourier algorithm can provide data support for the intelligent management of power supply systems, improving the system's intelligence level. Combining the advantages of Hall sensors and Fourier algorithms, it provides new ideas and methods for the development of leakage current 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 by this embodiment of the invention includes the following steps:

[0105] S2021: The preprocessed current signal is input into the Fourier transform to convert the time-domain signal into a frequency-domain signal, thus obtaining the different frequency components contained in the current signal.

[0106] S2022: Perform integration 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;

[0107] S2023: In the result of the Fourier transform, each frequency point corresponds to a complex value. The magnitude of the complex value represents the amplitude of the frequency component, while the phase angle represents the phase of the frequency component, thus 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 preprocessed current signal is first input into a Fourier transform to convert the time-domain signal into a frequency-domain signal, obtaining the 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 an 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 magnitude of the complex value represents the amplitude of the frequency component, and the phase angle represents the phase of the frequency component, thus decomposing the amplitude and phase of each harmonic in the current signal. Step S2021 of the above solution is the conversion from the time domain to the frequency domain. Through Fourier transform, the current signal in the time domain is converted into a frequency-domain signal; the conversion makes the frequency components of the signal clearly presented, which is convenient for the analysis and processing of each harmonic. Significance: Time-domain signals usually contain complex waveforms and transient changes, which are difficult to analyze directly; through Fourier transform, the signal is decomposed into components of different frequencies, making the characteristics of each harmonic prominent, laying the foundation for accurate extraction of amplitude and phase information. Step S2022, Integration and Inner Product Extraction, involves integrating the current signal and extracting the amplitude and phase information of each frequency component by performing inner products with sine and cosine functions of different frequencies; this achieves precise separation of the signal's frequency components. Significance: Integration and inner product operations are core mathematical techniques of the Fourier Transform, effectively extracting 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, involves resolving the complex value at each frequency point in the Fourier Transform result. The modulus of the complex value represents the amplitude of that frequency component, while the phase angle represents its phase; through this step, the amplitude and phase of each harmonic in the current signal are precisely decomposed. Significance: Complex value decomposition is the ultimate goal of Fourier transform, directly providing 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 insulation resistance. It realizes a comprehensive analysis of the frequency characteristics of current signals, providing accurate technical support for leakage detection and insulation resistance calculation.

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

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

[0111] S20221: Using Discrete Fourier Transform, calculate the inner product of the current signal with complex exponential functions 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] In the formula, F[k] represents the frequency domain signal with frequency index k, and represents the frequency of f[k]. The components are: 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, with a value range of 0≤k≤N-1; Let represent a complex exponential function, and let represent the frequency. The combination of sine and cosine functions; the current signal f[n] is decomposed into sine and cosine components of different frequencies;

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

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

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

[0117] S20222: Calculate the amplitude and phase of frequency components 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 is expressed in radians; arctan represents the arctangent function, used to calculate the phase angle.

[0124] S20223: For each harmonic in a current signal, its amplitude and phase are extracted 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 used to represent...

[0126]

[0127] In the formula, k n The frequency index of the nth harmonic is represented by Fk; P represents the number of periods of the signal; Fk is calculated by... n The amplitude Fk of the nth harmonic can be obtained. 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 complex exponential functions 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; secondly, the amplitude and phase of the frequency components are calculated through complex values; finally, for each harmonic in the current signal, its amplitude and phase are extracted by calculating specific frequency points. Step S20221 of the above solution 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 is that through this decomposition, the frequency components of the signal can be analyzed more intuitively, thus providing a basis for frequency domain analysis, filtering, denoising and other operations. Step S20222 calculates the amplitude and phase of the frequency components through the real and imaginary parts of the complex values, quantifying the intensity (amplitude) and phase information of each frequency component. Its significance lies in the fact that amplitude reflects the energy distribution of a signal at a specific frequency, while phase reveals the time offset or phase relationship of the signal at different frequency components; this information is crucial for accurate signal reconstruction, harmonic analysis, and system response evaluation. Step S20223, targeting each harmonic in the current signal, extracts the characteristics of each harmonic by calculating the amplitude and phase at specific frequency points; thus achieving accurate extraction and analysis of specific frequency components. Its significance lies in the fact that harmonic analysis is a core tool in power systems for tasks such as detecting nonlinear loads, assessing power quality, and diagnosing equipment faults. By extracting the amplitude and phase of harmonics, a deeper understanding of the system's operating status can be gained, providing 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 signal analysis and application.

[0130] Example 7: As Figure 7 As shown, based on Example 4, the process for determining whether a leakage current exists provided in this embodiment of the invention includes the following steps:

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

[0132] S20232: Based on parameter, amplitude, and phase information, obtain the calculation formula for insulation resistance;

[0133] The circuit is an equivalent circuit, which includes insulation resistance, distributed capacitance, line resistance and load resistance; the voltage and current relationship of the circuit is established by Kirchhoff's laws and Ohm's law.

[0134] By analyzing the spectrum, 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 For harmonic voltage, Z total The total impedance of the circuit;

[0138] Phase φ of harmonic current harmonic It reflects the characteristics of capacitors and inductors in the circuit; and further verifies the accuracy of the calculation results through phase information.

[0139] Based on the circuit model and the above analysis, the expression for insulation resistance is derived as follows:

[0140]

[0141] Among them, R line R is the line resistance. load R is the load resistance. load The amplitude φ of the harmonic current harmonic Indicates the phase of the 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 If R is positive, it is determined that there is a leakage current. threshold Indicates the safety threshold;

[0144] If R insulation≥ R threshold If so, it is considered to be in a 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 principles of circuits. The mathematical model incorporates parameters such as resistance, capacitance, and inductance in the circuit, along with the amplitude and phase information of harmonic currents. Secondly, based on the parameters, amplitude, and phase information, the calculation formula for insulation resistance is obtained. Finally, after calculating the insulation resistance value, it is compared with a preset safety threshold to determine whether leakage occurs. Step S20231 of the above solution constructs a mathematical model for calculating insulation resistance. By introducing parameters such as resistance, capacitance, and inductance in the circuit, an equivalent circuit model is constructed, which can comprehensively reflect the electrical characteristics of the circuit. Combined with the amplitude and phase information of harmonic currents, the nonlinear characteristics in the circuit can be analyzed more accurately, especially in the presence of harmonic interference. The significance achieved is that the mathematical model can accurately describe the electrical behavior of the circuit, providing a solid foundation for calculation and analysis. The model considers various parameters in the circuit, comprehensively reflecting the complexity of the circuit and improving the accuracy and reliability of the analysis. Step S20232 obtains the calculation formula for insulation resistance. Using Kirchhoff's laws and Ohm's law, the voltage and current relationship of the circuit is established, deriving the expression for insulation resistance. Spectrum analysis is used to extract the amplitude and phase information of harmonic currents at specific frequencies, further verifying the accuracy of the calculation results. Significance achieved: Formula derivation quantifies complex circuit characteristics into specific mathematical expressions, facilitating calculation and analysis; spectrum analysis and phase information verify the accuracy of the calculation results, ensuring the reliability of the analysis. Step S20233 compares the calculated insulation resistance value with a preset safety threshold. By comparing the calculated insulation resistance value with the preset safety threshold, the presence of leakage current can be quickly determined; setting the threshold enables automated judgment, improving detection efficiency and accuracy. Significance achieved: Comparison with the safety threshold allows for timely detection and handling of leakage current, ensuring the safe operation of the circuit; automation of leakage current detection reduces manual intervention and improves work efficiency and reliability.

[0146] In summary, this embodiment not only achieves comprehensive analysis and quantitative calculation of circuit characteristics, but also enables timely detection and handling of leakage phenomena through automated judgment, ensuring the safe operation of the circuit and improving work efficiency and reliability.

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

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

[0149] S302: A leakage current is detected, triggering an alarm mechanism to notify relevant personnel for handling; the alarm information includes the amplitude of the leakage current, the time of occurrence, and the specific location; at the same time, harmonic current is dynamically monitored to protect against leakage current in specific areas or equipment;

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

[0151] The working principle and beneficial effects of the above technical solution are as follows: Firstly, based on the distribution and changing 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 leakage occurs is located. Secondly, upon detecting the leakage phenomenon, an alarm mechanism is triggered to notify relevant personnel for handling. The alarm information includes the amplitude of the leakage current, the time of occurrence, and the specific location. Simultaneously, harmonic currents are dynamically monitored to protect against leakage in specific areas or equipment. Finally, the results of each leakage detection are recorded, including the characteristics of the leakage current, location information, and processing results. Step S301 of the above solution, by analyzing the distribution and changing trend of the current, combined with the actual layout of the coal mine and the topological structure of the power supply system, can accurately locate the specific area where leakage occurs. This location not only relies on current data but also incorporates geographical information to ensure accuracy. It can analyze current data in real time, quickly identify leakage phenomena, and immediately locate the leakage area, providing timely information support for alarms and handling. Significance Achieved: Precise area location can significantly shorten fault diagnosis time, reduce downtime and safety hazards caused by leakage, and improve coal mine production efficiency; by combining geographic information and power supply system topology, misjudgments can be avoided, ensuring that each alarm is based on accurate leakage detection results, reducing unnecessary maintenance and downtime. Step S302 Triggering the Alarm Mechanism and Dynamic Monitoring: Once a leakage phenomenon is detected, the system immediately triggers the alarm mechanism to notify relevant personnel for handling. Alarm information includes the amplitude of the leakage current, the time of occurrence, and the specific location, ensuring that relevant personnel can respond quickly; at the same time as the alarm, the system dynamically monitors the harmonic current to ensure continuous protection until the leakage problem is resolved; dynamic monitoring can also achieve selective leakage protection, that is, only protecting against leakage in specific areas or equipment to avoid false triggering. Significance Achieved: A timely alarm mechanism can ensure that relevant personnel can take measures quickly when a leakage occurs 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 equipment life, and reduce maintenance costs. Step S303 records the leakage current detection results, recording the results of each leakage current detection, including the characteristics of the leakage current, location information, and processing results. This data can be used for subsequent analysis and optimization, improving the system's detection accuracy and response speed. Analysis of historical data can identify potential fault modes, enabling preventative maintenance and reducing the occurrence of sudden failures. The significance is that through data accumulation and analysis, the detection algorithm and response mechanism can be continuously optimized, improving the system's intelligence level and adapting to different working environments and conditions. Analysis of historical data can help coal mine managers identify potential fault risks in advance, enabling preventative maintenance and reducing downtime and production losses caused by faults.

[0152] In summary, this embodiment can not only quickly and accurately determine the leakage current value and area, but also provide timely alarms, dynamic monitoring, and data recording, thereby improving the safety and reliability of underground power supply systems in coal mines. The integrated 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: As Figure 9 As shown, based on Example 8, the process of locating the specific area where leakage occurs provided in this embodiment of the invention includes the following steps:

[0154] S3011: Match the monitoring point of the current anomaly with the physical location in the underground layout. If the current anomaly occurs at the monitoring point of a certain power supply line, determine the actual physical location corresponding to the monitoring point based on the geographical information of the underground layout, such as a certain roadway or a certain working face.

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

[0156] S3013: After completing the matching of the geographic information of the current anomaly area with the underground layout and the analysis of the current path in the topology, information fusion is performed; the geographic information of the current anomaly area and the underground layout and the topology of the power supply system are combined 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.

[0157] The working principle and beneficial effects of the above technical solution are as follows: First, this embodiment maps the monitoring points of current anomalies to their physical locations in the underground layout. If a current anomaly occurs at a monitoring point on a certain power supply line, the actual physical location corresponding to the monitoring point, such as a certain roadway or a certain working face, is determined based on the geographical information of the underground layout. Second, the propagation path of the current anomaly is analyzed 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 current anomaly, the source of the current anomaly is determined. If the current anomaly occurs on a certain main power supply line, the branches of that line are further traced to analyze whether the current anomaly is caused by a certain branch line or a certain device. Finally, after completing the matching of the current anomaly area with the geographical information of the underground layout and the current path analysis in the topology, information fusion is performed. The current anomaly area is combined with the geographical information of the underground layout and the topology of the power supply system to form a comprehensive positioning model. This determines whether the current anomaly occurs on a specific power supply branch or on a specific device. Step S3011 of the above scheme maps the monitoring points of current anomalies to their physical locations in the underground layout. By mapping the monitoring points of current anomalies to the geographical information of the underground layout, abstract current data can be transformed into specific physical locations, such as a certain roadway or working face. This enables real-time location of the specific location of the current anomaly, providing basic data for analysis and processing. Significance: By quickly locating the physical location of the current anomaly, the time for troubleshooting can be greatly shortened, reducing production interruptions caused by leakage. Accurate location helps to take timely measures to prevent safety accidents caused by leakage and protect the lives of underground workers. Step S3012 utilizes the topology of the power supply system to analyze the propagation path of the current anomaly. By analyzing the topology of the power supply system, the propagation path of the current anomaly can be traced to determine the source of the anomaly, such as a certain branch line or a certain piece of equipment. This helps to identify the specific source of the current anomaly, whether it is a line problem or equipment failure. Significance: Through path analysis, the fault source can be accurately identified, avoiding unnecessary inspection of the entire power supply system and improving the efficiency of fault handling. Understanding the propagation path of the current anomaly helps to develop more effective maintenance strategies and prevent similar problems from recurring. Step S3013 involves information fusion to form a comprehensive positioning model. This model combines the area of ​​current anomaly with the geographic information of the underground layout and the topology of the power supply system, ensuring the accuracy and comprehensiveness of the positioning. Through information fusion, the positioning model can be continuously optimized, improving its adaptability to complex environments. The significance is that comprehensive analysis improves positioning accuracy, ensuring that every fault can be accurately located and handled. Continuous optimization of the positioning model enhances the reliability of the entire monitoring system, ensuring effective operation 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 constitute an efficient and accurate leakage current location system, which not only improves the efficiency of fault handling but also enhances the safety and reliability of downhole operations.

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

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

[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, and the operating status of the equipment. The propagation path of the current anomaly is analyzed using the topology. The source and propagation direction of the current anomaly are determined through path analysis. If the current anomaly occurs on a main power supply line, the branches of the line are traced to analyze whether the current anomaly is caused by a branch line or a certain equipment.

[0162] S30133: Based on the results of feature extraction and path analysis, perform location calculations and determine the specific location of the current anomaly using a topology-based location algorithm; output the location calculation results to the result output layer, where the output result is a specific physical location, such as a certain tunnel or a certain working face; and present it in graphical form.

[0163] The working principle and beneficial effects of the above technical solution are as follows: This embodiment first designs a comprehensive positioning model framework based on the fused information data, including an input layer, a processing layer, and an output layer; the input layer receives geographic information, topology, 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, and the working status of the equipment; the propagation path of the current anomaly is analyzed using the topology; through path analysis, the source and propagation direction of the current anomaly are determined; if the current anomaly occurs on a main power supply line, the branches of the line are traced, and it is analyzed whether the current anomaly is caused by a branch line or a piece of equipment; finally, based on the results of feature extraction and path analysis, positioning calculation is performed, and the positioning algorithm based on the topology determines the specific location of the current anomaly; 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 certain tunnel or a certain working face; presented in graphical form. Step S30131 of the above scheme designs a comprehensive positioning model framework. By clearly defining the input layer, processing layer, and output layer, the model structure is clear, facilitating maintenance and upgrades. The input layer receives various types of data (geographic information, topology, and current anomaly data), enhancing the model's data processing capabilities and adaptability. The significance is that it provides a systematic framework for data analysis and feature extraction, ensuring the coherence and consistency of data processing; through the fusion of multi-source data, current anomalies can be analyzed more comprehensively, thereby improving positioning accuracy. Step S30132 involves feature extraction and path analysis, extracting key features such as the intensity, propagation path, and equipment status of current anomalies to provide data support for positioning calculations; using topology analysis to determine the propagation path of current anomalies allows for tracing the source and direction of propagation, facilitating rapid problem localization. The significance is that through feature extraction and path analysis, the source of current anomalies can be accurately identified, reducing false positives and false negatives; path analysis helps to quickly locate problems, shortening troubleshooting time and improving system response speed. Step S30133, location calculation and result output, utilizes a topology-based positioning algorithm to accurately calculate the specific location of current anomalies. The positioning results are presented graphically for intuitive understanding and operation. The significance lies in the fact that the positioning calculation pinpoints the exact physical location (e.g., a specific tunnel or working face), providing clear guidance for maintenance and handling. The graphical presentation of the results facilitates quick understanding and execution by operators, improving work efficiency.

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

[0165] Example 11: As Figure 11 As shown, based on Embodiments 1-9, the 3DR leakage current detection and protection method for underground coal mines provided by the present invention consists of a 3DR leakage current 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] The 3DR leakage current detection module 1 has its input terminal connected to the power supply system of the substation. The voltage of the substation power supply system is AC10000V, 6000V, 3300V, 1905V, 1140V, and 660V, etc. The 3DR leakage current detection module 1 includes diodes, probes, and resistors. The 3DR leakage current detection module 1 is connected to the Vdc interface of the MCU processor 2. The Rs interface and PE terminal of the MCU processor 2 are connected to the bridge-type additional DC detection module 3. The input terminal of the bridge-type additional DC detection module 3 is AC100V. The Udc interface of the MCU processor 2 is connected to the input terminal of the automatic switching module 4. The automatic switching module 4 is connected to the input terminal of the 3DR leakage current 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. The other end of the 6 and the Rsy test resistor are connected to the ground terminal.

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

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

[0169] This embodiment utilizes Fourier series and harmonic analysis to accurately detect leakage current, improving detection accuracy. The dynamic correction module adjusts detection parameters in real time to adapt to different operating conditions, ensuring detection stability and reliability. The automatic switching module automatically adjusts the detection mode based on voltage conditions, simplifying operation and improving system intelligence. The distributed capacitance detection module detects distributed capacitance in the system, helping to identify potential leakage risks and improving system safety. Based on 3DR technology, the system can adapt to IT power supply systems of different voltage levels, achieving leakage current detection for 6-pulse and 12-pulse frequency converters, demonstrating wide applicability. It can monitor and protect in real time, promptly detecting and handling leakage problems to ensure safe operation in coal mines. It achieves high precision, dynamic correction, automatic switching, and distributed capacitance detection functions, effectively improving the electrical safety level in coal mines.

[0170] Example 12: As Figure 12 As shown, based on Embodiment 11, the schematic diagram of the 6-pulse frequency converter 3DR leakage detection system for the coal mine underground dynamic converter substation power supply system provided by this embodiment of the invention includes: 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 current detection module 1, the 3DR leakage current 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 in this embodiment is the core part of the underground power supply system in the coal mine. It is mainly responsible for converting high-voltage electricity into low-voltage electricity suitable for underground equipment; converting high-voltage AC electricity into low-voltage DC electricity through transformers and rectifiers to provide a 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; it determines whether leakage exists by detecting current imbalance in the circuit, and immediately cuts off the power supply once leakage is detected to prevent accidents; improving the safety of the underground power supply system and effectively preventing electrical accidents. The harmonic current detection module 8 is used to detect harmonic current in the circuit to prevent harmonics from damaging equipment and the power grid; through filters and detection circuits, it monitors the harmonic components in the circuit in real time, and immediately takes measures to suppress them once harmonics exceed the standard; protecting equipment and the power grid from harmonic damage and improving power supply quality. Rectifier 9 is a device that converts alternating current (AC) to direct current (DC), providing a stable DC power supply for the inverter. Through components such as diodes or thyristors, it converts AC to DC, eliminating voltage fluctuations and providing a stable power supply for the inverter. This ensures the stable operation of the inverter and motor, improving system reliability. Inverter 10 is a device that converts DC to AC, providing an adjustable AC power supply for the motor. Through power switching components such as IGBTs, it converts DC to AC with adjustable frequency and voltage to meet different operating requirements of the motor. This enables stepless speed regulation of the motor, improving equipment operating efficiency and flexibility. Motor 11 is the power source for underground coal mine equipment. It converts electrical energy into mechanical energy to drive the equipment. Through the principle of electromagnetic induction, it converts electrical energy into mechanical energy to drive the equipment's rotation or movement. It provides stable and reliable power, ensuring the normal operation of underground equipment.

[0173] In this embodiment, the converter substation 7 is connected to the 3DR leakage current detection module 1 to ensure the safety of the power supply system; the 3DR leakage current detection module 1 is connected to the harmonic current detection module 8 to monitor leakage current 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 rectifier input; the rectifier 9 is connected to the inverter 10 to provide a stable DC power supply to the inverter; and the inverter 10 is connected to the motor 11 to provide an adjustable AC power supply to the motor to drive the equipment. Through the organic combination of the above structures, the entire system can achieve efficient, safe, and stable power supply, ensuring the safe operation of equipment in the coal mine. In the leakage current protection of the mobile 6-pulse frequency converter, data such as the fundamental component, carrier frequency, and harmonic components in the system voltage are detected and sent to the MCU processor through the 3DR leakage current detection channel to protect the system from leakage.

[0174] Example 13: As Figure 13As shown, based on Embodiment 11, the 12-pulse 3DR leakage current detection system for the underground mobile converter substation in coal mines provided by this embodiment of the invention includes: a high-voltage switch 12, a 12-pulse mobile converter substation 13, a 3DR leakage current detection module 1, a harmonic current detection module 8, a VFD frequency converter 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 current detection module 1, the 3DR leakage current detection module 1 is connected to the harmonic current detection module 8, the harmonic current detection module 8 is connected to the VFD frequency converter 14, and the VFD frequency converter 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, as the system's entry point, is responsible for controlling the connection and disconnection of high-voltage electricity, ensuring the safe operation of the system. The 12-pulse mobile converter substation 13 uses 12-pulse rectification technology to convert high-voltage AC power into low-voltage DC power, reducing harmonic pollution and improving power quality. The 12-pulse rectification, through the parallel connection of two 6-pulse rectifier bridges, utilizes phase difference to achieve mutual cancellation of harmonics, thereby reducing harmonic content. The 3DR leakage current detection module 1 monitors the system's leakage current in real time by detecting leakage current in the circuit. Through three-phase detection, the 3DR leakage current detection module 1 can more accurately capture leakage signals, ensuring the safe operation of the system. The harmonic current detection module 8 is used to detect harmonic currents in the system, especially harmonics generated by the frequency converter. By detecting harmonic currents, the system's power quality can be monitored in real time, providing data support 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 generates harmonics during operation. The harmonic current detection module 8 can monitor these harmonics in real time to ensure stable system operation. The motor 11 is the final load device, and the speed is regulated by the frequency converter to meet the needs of different working conditions in the coal mine.

[0177] This embodiment utilizes 12-pulse rectification technology to effectively reduce harmonic pollution and improve power quality. The 12-pulse rectification, achieved through the parallel connection of two sets of 6-pulse rectifier bridges, uses phase difference to cancel out harmonics, thereby reducing harmonic content and ensuring the stability and reliability of the power supply system. The 3DR leakage current detection module 1, through three-phase detection, can more accurately capture leakage signals, ensuring the safe operation of the system. When leakage is detected, the system can quickly cut off the power supply to prevent 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 harmonic current, the power quality of the system can be monitored in real time, providing data support for subsequent harmonic suppression and ensuring stable system operation. The VFD frequency converter 14, by adjusting the output frequency and voltage, achieves precise control of the motor 11, meeting the needs of different working conditions in coal mines; the use of the frequency converter not only improves the operating efficiency of the motor but also reduces energy consumption. The high-voltage switch 12 allows for rapid power cut-off when necessary, ensuring system safety. Simultaneously, the real-time monitoring by the 3DR leakage current detection module 1 further enhances the system's safety performance. It can adapt to the complex and ever-changing working conditions in coal mines, ensuring stable operation in various environments.

[0178] In summary, the 12-pulse 3DR leakage current detection technology solution for the mobile converter substation power supply system in coal mines of this embodiment ensures the safe, stable, and efficient operation of the system through multiple detection and protection mechanisms, providing reliable power supply for underground coal mine production. It utilizes the three-phase half-wave of the converter substation power supply system, constructing a common auxiliary star point connected to the dual-voltage system through common cathode and common anode wiring; it detects the harmonic components flowing through the detector resistor to obtain data such as the system voltage fundamental component, carrier frequency, and harmonic components. Given the dual-voltage power supply, the dual 3DR leakage current detection channels are combined to construct the auxiliary star point, which is then fed into the MCU processor for system leakage current protection.

[0179] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of equivalents of this invention, this invention is also intended to include these modifications and variations.

Claims

1. A 3DR leakage current detection and protection method for underground coal mines, characterized in that, 3D represents amplitude, frequency, and phase. Amplitude represents the magnitude of the current, frequency represents the fluctuation frequency of the current, and phase represents the phase relationship of the current. R represents residual current, referring to the extra current beyond the normal operating current, which includes the following steps: Using the three-phase half-wave power supply system of the converter substation, an auxiliary star point is constructed to connect with the power supply system of the converter substation through common cathode or common anode wiring; The residual current Hall sensor is used to detect the residual current of leakage current with different harmonics, and the technology of 3DR leakage current measurement insulation resistance is identified based on the Fourier algorithm. Based on harmonic components, the leakage resistance of the frequency converter in the power supply system of the mobile converter substation in the coal mine can be quickly determined to identify the leakage value and area and perform judgment alarm protection; and the harmonic current can be dynamically detected to achieve selective leakage protection. The process of constructing an auxiliary star point connected to the power supply system of the converter substation includes the following steps: The three-phase voltage is rectified by a three-phase half-wave rectifier circuit, which consists of three sets of diodes, each corresponding to the positive or negative half-cycle of the three-phase voltage. In the three-phase half-wave rectifier circuit, the diodes are connected in a common cathode or common anode configuration to convert the three-phase voltage into a DC voltage, while also forming an auxiliary star point. After rectification, the voltage of the power supply system of the converter substation forms a DC voltage at the auxiliary star point. The DC voltage is then filtered. The DC voltage is the average value of the three-phase voltage and reflects the overall voltage level of the power supply system of the converter substation. By using Fourier transform, the waveform of DC voltage is decomposed into components of different frequencies. The fundamental component corresponds to the basic frequency of the DC substation power supply system, while the carrier component corresponds to the high-frequency components. The fundamental and carrier components are extracted using a bandpass filter; the current changes in the power supply system are monitored in real time using a Hall current sensor, and the waveform of the residual leakage current is extracted. The process of decomposing a DC voltage waveform into components of different frequencies includes the following steps: The DC voltage signal, after rectification and filtering, is obtained from the auxiliary star point. The pre-processed DC voltage signal is transformed from the time domain to the frequency domain using Fourier transform. 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 the fundamental component and the carrier component. The fundamental component corresponds to the basic frequency of the DC substation power supply system and reflects the basic voltage characteristics. The carrier component is a high-frequency component that reflects nonlinear characteristics. The frequency domain signal is processed using a bandpass filter to extract the fundamental component and the carrier component respectively. Hall current sensors measure the instantaneous value of current and decompose the current signal into components of different frequencies through Fourier transform. By analyzing the components, the waveform of the residual leakage current is extracted.

2. The 3DR leakage current detection and protection method for underground coal mines as described in claim 1, characterized in that, The process of identifying 3DR leakage current measurement insulation resistance techniques based on the Fourier algorithm includes the following steps: Hall effect sensors collect residual current signals 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; The preprocessed current signal is input into the Fourier transform to decompose the amplitude and phase information of each harmonic. Based on the results of the Fourier transform, analyze the amplitude and phase of each harmonic current; Based on the circuit parameters of the power supply system of the converter substation, the insulation resistance value in the 3DR leakage current measurement is calculated; based on the calculated insulation resistance value, it is determined whether there is a leakage current phenomenon.

3. The 3DR leakage current detection and protection method for underground coal mines as described in claim 2, 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 a Fourier transform to convert the time-domain signal into a frequency-domain signal, thus obtaining the different frequency components contained in the current signal. The current signal is integrated, and the amplitude and phase information of each frequency component in the current signal are extracted by performing an inner product with sine and cosine functions of different frequencies. In the Fourier transform, each frequency point corresponds to a complex value. The magnitude of the complex value represents the amplitude of the frequency component, while the phase angle represents the phase of the frequency component, thus decomposing the amplitude and phase of each harmonic in the current signal.

4. The 3DR leakage current detection and protection method for underground coal mines as described in claim 3, characterized in that, The process of extracting the amplitude and phase information of each frequency component in a current signal includes the following steps: The Discrete Fourier Transform is used to calculate the inner product of the current signal with complex exponential functions 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. The amplitude and phase of the frequency components are calculated using complex values. For each harmonic in the current signal, its amplitude and phase are extracted by calculating the corresponding frequency points.

5. The 3DR leakage current detection and protection method for underground coal mines as described in claim 2, characterized in that, The process of determining whether there is a leakage current includes the following steps: A mathematical model for calculating insulation resistance is constructed based on the basic principles of circuits. The mathematical model incorporates the resistance, capacitance, and inductance parameters of the circuit, and combines the amplitude and phase information of harmonic currents. Based on parameter, amplitude, and phase information, the formula for calculating insulation resistance is obtained; After calculating the insulation resistance value, it is compared with the preset safety threshold to determine whether there is leakage.

6. The 3DR leakage current detection and protection method for underground coal mines as described in claim 1, characterized in that, The process of quickly determining the leakage current value and area, and then triggering an alarm protection, includes the following steps: Based on the distribution and trend of the current, combined with the actual layout of the coal mine and the topological geographical information of the power supply system, the specific area where the leakage occurred can be located. If a leakage current is detected, an alarm mechanism is triggered to notify relevant personnel for handling. The alarm information includes the amplitude of the leakage current, the time of occurrence, and the specific location. At the same time, harmonic currents are dynamically monitored to protect against leakage current in the corresponding area or equipment. Record the results of each leakage current detection, including the characteristics of the leakage current, location information, and processing results.

7. The 3DR leakage current detection and protection method for underground coal mines as described in claim 6, characterized in that, The process of locating the specific area where a leakage current occurs includes the following steps: The monitoring points of abnormal current are mapped to their physical locations in the underground layout. If an abnormal current occurs at a monitoring point on a certain power supply line, the actual physical location corresponding to the monitoring point is determined based on the geographical information of the underground layout. By utilizing the topology of the power supply system, the propagation path of current anomalies is analyzed. The topology describes the connection relationship between various devices and lines in the power supply system. By analyzing the propagation path of current anomalies, the source of the current anomalies can be determined. After completing the matching of the current anomaly area with the geographic information of the underground layout and the analysis of the current path in the topology, information fusion is performed; the current anomaly area is combined with the geographic information of the underground layout and the topology of the power supply system to form a comprehensive positioning model; it is determined that the current anomaly occurs on a corresponding power supply branch or on a specific device.

8. The 3DR leakage current detection and protection method for underground coal mines as described in claim 7, characterized in that, If an abnormal current occurs on a main power supply line, further trace the branches of that line and analyze whether the abnormal current is caused by a branch line or a certain device.

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