Personal shock protection device and method for an automatically phase-selecting split-phase three-phase power supply system

Abstract

This disclosure relates to the field of mine power supply safety technology, and in particular provides an automatic phase selection and current shunting device and method for protecting against electric shock in a three-phase power supply system. The device includes: a ground insulation resistance detection module for detecting the ground insulation resistance of each phase line; a ground voltage detection module for detecting the ground voltage of each phase line; a fault phase shunt leakage current protection module for determining the fault phase based on the ground voltage of each phase line if the ground insulation resistance meets the suspected electric shock fault conditions; a shunt grounding solid-state switch including shunt branches between each phase line and the ground, each shunt branch including a series solid-state switch unit and a current-limiting resistor; and a fault phase shunt leakage current protection module for triggering the solid-state switch unit corresponding to the fault to conduct, connecting the current-limiting resistor between the fault phase and the ground to form a shunt path, and controlling the circuit breaker to trip. This disclosure solves the problems of easily exceeding the limit of electric shock current, long fault current duration, and poor adaptability.

Description

Technical Field

[0001] This disclosure relates to the field of mine power supply safety technology, and in particular to a device and method for protecting personnel from electric shock in a three-phase power supply system with automatic phase selection and current diversion. Background Technology

[0002] To improve production efficiency, 10kV high-voltage power supply systems are widely used in fully mechanized coal mining faces. Meanwhile, to ensure worker safety, 10 / 10.5kV isolation transformers are often added to the mining area substation, with their secondary sides operating in a neutral-point ungrounded mode to limit single-phase ground fault current and electric shock current.

[0003] In related technologies, isolation transformers are used in conjunction with residual current devices (RCDs) for personal electric shock protection. The principle is that when the system's insulation resistance to ground drops to a set threshold, the RCD controls the high-voltage circuit breaker to trip, cutting off the power supply. However, this method typically suffers from problems such as the risk of excessive electric shock current, long fault current duration, and poor adaptability due to dependence on line conditions. Summary of the Invention

[0004] This disclosure is made in view of the above-mentioned problems. This disclosure provides a device and method for protecting against electric shock in a three-phase power supply system with automatic phase selection and current shunt.

[0005] According to one aspect of this disclosure, an automatic phase-selective current-shunting device for electric shock protection in a three-phase power supply system is provided. The three-phase power supply system uses an isolation transformer with an ungrounded neutral point on the secondary side. The device includes: a ground insulation resistance detection module for detecting the ground insulation resistance of each phase line in the three-phase power supply system; a ground voltage detection module for detecting the ground voltage of each phase line in the three-phase power supply system; and a fault phase shunt leakage current protection module, which is signal-connected to both the ground insulation resistance detection module and the ground voltage detection module, and is used to automatically select phase and shunt current when the ground insulation resistance meets the conditions for a suspected electric shock fault. The faulty phase is determined based on the voltage to ground of each phase line; a shunt grounding solid-state switch, including shunt branches connected to the ground between phase A, phase B, and phase C lines respectively, each shunt branch including a solid-state switch unit and a current-limiting resistor connected in series; a circuit breaker trip control module, which is signal-connected to the faulty phase shunt leakage protection module; wherein, after the faulty phase is determined, the faulty phase shunt leakage protection module is used to trigger the solid-state switch unit corresponding to the fault to conduct, so that the corresponding current-limiting resistor is connected between the faulty phase and the ground to form a shunt path to ground, and controls the circuit breaker to trip through the circuit breaker trip control module.

[0006] According to another aspect of this disclosure, an automatic phase-selective current shunting method for personal electric shock protection in a three-phase power supply system is provided, applied to the automatic phase-selective current shunting method for personal electric shock protection in a three-phase power supply system provided in the embodiments of this disclosure. The method includes: a ground insulation resistance detection module detecting the ground insulation resistance of each phase line in the three-phase power supply system; a ground voltage detection module detecting the ground voltage of each phase line in the three-phase power supply system; a fault phase shunt leakage current protection module determining the fault phase based on the ground voltage of each phase line when the ground insulation resistance meets the suspected personal electric shock fault conditions; after determining the fault phase, triggering the corresponding solid-state switch unit to conduct, so that the corresponding current-limiting resistor is connected between the fault phase and the ground to form a ground shunt path, and controlling the circuit breaker to trip through the circuit breaker tripping control module.

[0007] As will be described in detail below, an automatic phase-selective current-shunting three-phase power supply system electric shock protection device according to an embodiment of the present disclosure includes: a ground insulation resistance detection module for detecting the ground insulation resistance of each phase line in the three-phase power supply system; a ground voltage detection module for detecting the ground voltage of each phase line in the three-phase power supply system; and a fault phase shunt leakage current protection module, which is signal-connected to the ground insulation resistance detection module and the ground voltage detection module respectively, and is used to determine the ground voltage of each phase line when the ground insulation resistance meets the suspected electric shock fault conditions. The faulty phase; the shunt grounding solid-state switch includes shunt branches connected to the ground between phase A, phase B, and phase C lines respectively. Each shunt branch includes a solid-state switch unit and a current-limiting resistor connected in series. The circuit breaker trip control module is signal-connected to the faulty phase shunt leakage protection module. The faulty phase shunt leakage protection module is used to trigger the corresponding solid-state switch unit to conduct after the faulty phase is identified, so that the corresponding current-limiting resistor is connected between the faulty phase and the ground to form a shunt path to ground, and controls the circuit breaker to trip through the circuit breaker trip control module. The entire process forms a complete protection chain of "real-time monitoring → precise phase selection → rapid current shunting and limiting → reliable power disconnection". It not only meets the stringent requirements of personal electric shock protection for action speed and current limiting capability, but also avoids the risk of long-term current flow in solid-state switching units and current-limiting resistors by ultimately cutting off the power supply. It significantly improves the personal safety protection level and operational reliability of three-phase power supply systems, and solves the problems of easy exceedance of personal electric shock current, long fault current action time, and poor adaptability due to dependence on line conditions in related technologies.

[0008] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further illustration of the claimed technology. Attached Figure Description

[0009] The above and other objects, features, and advantages of this disclosure will become more apparent from the more detailed description of the embodiments thereof in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the disclosure and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0010] Figure 1 This diagram illustrates the principle of electric shock in a frequency converter-free power supply system in related technologies. Figure 2 An equivalent circuit diagram of the electric shock principle of a frequency converter-free power supply system in the related art is shown; Figure 3 A schematic diagram of the frame of the automatic phase selection and current shunting three-phase power supply system personal electric shock protection device provided in an exemplary embodiment of the present disclosure is shown. Figure 4 This diagram illustrates the principle of automatic shunt protection technology for personal electric shock faults provided by an exemplary embodiment of this disclosure; Figure 5 A circuit diagram of a ground insulation resistance detection module provided in an exemplary embodiment of this disclosure is shown; Figure 6 A circuit diagram of a ground voltage detection module provided in an exemplary embodiment of this disclosure is shown; Figure 7 A circuit block diagram of phase-selective shunt leakage protection provided by an exemplary embodiment of the present disclosure is shown; Figure 8 A schematic diagram of a single-phase leakage fault in a neutral-point ungrounded system provided in an exemplary embodiment of this disclosure is shown. Figure 9 A schematic diagram of voltage phasors during a phase A fault, provided by an exemplary embodiment of this disclosure, is shown. Figure 10 A schematic diagram of voltage phasors during a phase B fault, provided by an exemplary embodiment of this disclosure, is shown. Figure 11 A circuit diagram of a shunt grounding solid-state switch provided in an exemplary embodiment of this disclosure is shown; Figure 12 The diagram illustrates a waveform of personal current in a neutral-point ungrounded system provided by an exemplary embodiment of this disclosure. Figure 13 The diagram illustrates a personal current waveform of another neutral-point ungrounded system provided by an exemplary embodiment of this disclosure; Figure 14 A flowchart illustrating an exemplary embodiment of the present disclosure of a method for protecting a person from electric shock in a three-phase power supply system with automatic phase selection and current shunting is shown. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this disclosure more apparent, exemplary embodiments according to this disclosure will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this disclosure, and not all embodiments of this disclosure. It should be understood that this disclosure is not limited to the exemplary embodiments described herein.

[0012] It should be understood that the steps described in the method embodiments of this disclosure may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this disclosure is not limited in this respect.

[0013] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below. It should be noted that the concepts of "first", "second", etc., used in this disclosure are only used to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0014] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0015] The names of messages or information exchanged between multiple devices in the embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of such messages or information.

[0016] When the electrical equipment in the longwall mining face of a mine adopts a 10kV high-voltage power supply system, the probability of workers being directly exposed to electric shock increases. Therefore, a 10 / 10.5kV isolation transformer is added to the substation in the mining area. This is to improve the quality of the terminal voltage and to reduce the single-phase ground fault current and the electric shock current, so as to minimize the occurrence of electric shock accidents.

[0017] The power supply system for the fully mechanized mining face, powered by a 10 / 10.5kV explosion-proof isolation transformer, primarily supplies electrical production equipment such as the coal mining machine and scraper conveyor. The coal mining machine's cutting motor uses a direct drive, while the scraper conveyor uses a frequency converter integrated drive. The electrical principle of the power supply line directly driving the motor (i.e., a power supply system without a frequency converter as a load) in the event of an electric shock accident is as follows: Figure 1 As shown. Figure 1 The diagram illustrates the principle of electric shock in a frequency converter-free power supply system in related technologies, such as... Figure 1 As shown, A, B, and C represent three-phase symmetrical power frequency AC power supplies; r A This represents the insulation resistance to ground of phase A; r B This indicates the insulation resistance to ground of phase B; r C This indicates the insulation resistance to ground of phase C; C A This represents the distributed capacitance to ground of phase A; C B This represents the distributed capacitance to ground of phase B; C C This represents the distributed capacitance of phase C to ground. It represents the body's electrical resistance.

[0018] For ease of analysis and calculation, the human body impedance model is set as a pure resistance, and the three-phase power supply system is assumed to always be in a three-phase symmetrical state, that is, the insulation resistance to ground of each phase is equal. r A , r B and r C Set the value to r The distributed capacitance to ground of each phase is equal. C A , C B and C C Let the value be C. At this point... Figure 1 Equivalent circuit diagram as follows Figure 2 As shown. Figure 2 An equivalent circuit diagram of the principle of electric shock to a person in a frequency converter-free power supply system in the related art is shown.

[0019] analyze Figure 2 The circuit shown can be used to obtain the following calculation formula: (1) (2) in, Represents the equivalent complex impedance to ground; Represents the imaginary unit; Indicates the angular velocity of the power frequency AC grid; Indicates the electric current in a person's body; This represents the phase voltage of phase A.

[0020] Substituting formula (1) into formula (2), we get: (3) Formula (3) above is the phasor formula for calculating the electric shock current. From the phasor formula, the effective value of the electric shock current can be obtained as follows: (4) in, Indicates the effective value of the electric shock current to a person; Table of effective values ​​of phase voltage in power supply system.

[0021] The line voltage (through the effective value of the phase voltage) The phase-to-line voltage conversion yielded a value of 10500V, which is the resistance of human body to electric shock. The insulation resistance of each phase to ground is 1000Ω. r Given a current of 100 MΩ and a relative capacitance C of 0.1 µF, the effective value of the electric shock current to a person is calculated using the following formula: (5) Using the above formula, the electric shock current value of a person can be calculated under different parameters such as system line voltage, insulation resistance to ground, distributed capacitance, and personal resistance.

[0022] The technical solution of using an isolation transformer in conjunction with a leakage current protection device for personal electric shock protection has significant drawbacks, as follows: 1. The electric current of a person is prone to exceed the standard, and there is a high risk of exceeding the safety threshold.

[0023] (1) Defect manifestation: When the distributed capacitance on the secondary side of the isolation transformer is very small and the three-phase ground insulation resistance is high (greater than 600kΩ / phase), the electric shock current can be limited to less than 30mA. However, as long as the distributed capacitance reaches 0.1μF / phase, considering the human resistance of 1kΩ and 3kΩ, the electric shock current is 569mA and 559mA respectively; if the distributed capacitance increases to 1μF / phase, still considering the human resistance of 1kΩ and 3kΩ, the electric shock current is as high as 4115mA and 2977mA, both of which are far greater than the safe current.

[0024] (2) Root cause: Existing technology does not design active diversion measures to address the problem of "increased distributed capacitance leading to increased fault current". It relies solely on the inherent characteristics of isolation transformers. However, factors such as increased cable length in fully mechanized mining faces and humid underground environments inevitably increase distributed capacitance, leading to failure of protection capabilities.

[0025] 2. The fault current has been acting for too long, exceeding the safety parameter requirements.

[0026] (1) Defect manifestation: Even if the leakage protection device can detect the fault and issue a trip command quickly (within 30ms), the personal fault current generally exists for more than 50ms due to the inherent operating time of the circuit breaker. At this time, the product of current and time (mAs) reaches 28.45mAs (0.1μF / phase, 1kΩ), 27.95mAs (0.1μF / phase, 3kΩ), 205.75mAs (1μF / phase, 1kΩ), and 148.85mAs (1μF / phase, 3kΩ), respectively. Only when the distributed capacitance is extremely small can it barely meet the requirement of 30mAs for the electrical safety parameter of the mine. If the distributed capacitance is slightly large, it will exceed the safety threshold and greatly increase the probability of injury and death.

[0027] (2) Root cause: Existing technology relies solely on the single protection method of "tripping and power outage" and does not set up an intermediate protection link to quickly reduce the electric shock current before "tripping", resulting in the fault current continuously acting on the human body during the operation of the circuit breaker.

[0028] 3. The protection effect depends on the line conditions, resulting in poor adaptability.

[0029] (1) Defects: The effective protection range of existing technologies is limited to scenarios where "the secondary side cable of the isolation substation is very short and the distributed capacitance is very small". When the secondary side cable of the isolation substation is very short and the distributed capacitance is very small, the product of the electric shock current and the duration of the shock meets the requirement of 30 mAs for the electrical safety parameter of the mine. However, when the distributed capacitance is large, the electric shock to the person is much greater than the requirement of 30 mAs for the electrical safety parameter of the mine, and the probability of injury or death is high. When the cable length increases (such as the extension of the power supply distance due to the advancement of the fully mechanized mining face), the cable insulation ages, or the humidity of the underground environment increases, the distributed capacitance increases, the protection effect drops sharply, and it cannot adapt to the complex and ever-changing underground power supply environment.

[0030] (2) Root cause: The protection logic does not take into account the dynamic changes of the on-site working conditions and lacks the ability to adapt and adjust. It is a passive protection rather than an active intervention.

[0031] Therefore, to solve the above problems, this disclosure provides an automatic phase selection and current shunting three-phase power supply system electric shock protection device. It aims to address three core problems faced by personnel accidentally touching live parts during a single-phase grounding fault in a 10kV high-voltage power supply system deep in coal mine longwall mining faces: the harsh underground environment (humid, dusty), the susceptibility of cables to mechanical damage leading to insulation failure, and poor adaptability due to line conditions. Specifically, it aims to: address the increased electric shock current caused by increased distributed capacitance by designing active current shunting measures to reduce the electric shock current flowing through the human body to within a safe threshold; address the excessively long fault current duration by achieving rapid response (millisecond level) after a fault, reducing the electric shock current before the circuit breaker trips and shortening the duration of high-risk current; and address the poor adaptability due to line conditions by designing an automatic fault phase identification function, accurately locating the fault phase without manual intervention, adapting to different cable lengths and distributed capacitances, and ensuring stable protection.

[0032] The automatic phase-selective current-shunting three-phase power supply system electric shock protection device provided in this embodiment uses an isolation transformer with an ungrounded neutral point on the secondary side. In fully mechanized mining faces, a 10kV three-phase power supply system using an isolation transformer can be adopted, with the neutral point of its secondary winding ungrounded.

[0033] Figure 3 A schematic diagram of the frame of an automatic phase-selective current-shunting three-phase power supply system electric shock protection device provided in an exemplary embodiment of this disclosure is shown. Figure 3 As shown, the automatic phase-selective current shunt three-phase power supply system electric shock protection device includes: The ground insulation resistance detection module 301 is used to detect the ground insulation resistance of each phase line in a three-phase power supply system. The voltage to ground detection module 302 is used to detect the voltage to ground of each phase line in a three-phase power supply system; The fault phase shunt leakage current protection module 303 is connected to the ground insulation resistance detection module 301 and the ground voltage detection module 302 respectively. It is used to determine the fault phase based on the ground voltage of each phase line when the ground insulation resistance meets the conditions for suspected electric shock. The shunt grounding solid-state switch 304 includes shunt branches connected to the ground between phase A line, phase B line and phase C line respectively. Each shunt branch includes a solid-state switch unit and a current-limiting resistor arranged in series. The circuit breaker trip control module 305 is signal-connected to the fault phase shunt leakage current protection module 303; The fault phase shunt leakage protection module 303 is used to trigger the corresponding solid-state switch unit to conduct after the fault phase is determined, so that the corresponding current limiting resistor is connected between the fault phase and the ground to form a ground shunt path, and the circuit breaker tripping control module 305 controls the circuit breaker to trip.

[0034] Specifically, the ground insulation resistance detection module 301 monitors the ground insulation resistance between each phase of the three-phase power supply system and the ground in real time, and transmits the ground insulation resistance to the fault phase shunt leakage current protection module 303. The ground voltage detection module 302 monitors the ground voltage of each of the A-phase, B-phase, and C-phase lines in the three-phase power supply system in real time, and sends the ground voltage to the fault phase shunt leakage current protection module 303.

[0035] The fault phase shunt leakage current protection module 303 is connected to the ground insulation resistance detection module 301 and the ground voltage detection module 302 respectively. The fault phase shunt leakage current protection module 303 is internally set with suspected human electric shock fault conditions and fault phase judgment conditions.

[0036] The fault phase shunt leakage current protection module 303 can determine whether the insulation resistance to ground meets the conditions for suspected electric shock. If the insulation resistance to ground meets the conditions for suspected electric shock, it determines the fault phase in phase A, phase B and phase C based on the voltage to ground of each phase line and the judgment conditions of the fault phase, thereby realizing the automatic judgment of the fault phase in which electric shock occurs.

[0037] Here, the fault phase shunt leakage protection module 303 adopts dual logic of resistance condition and voltage phase selection, which can effectively eliminate false triggering under non-electric shock conditions such as motor start-up and harmonic interference. At the same time, it can automatically identify which phase was touched by a person, providing directional control commands for subsequent accurate shunt.

[0038] Figure 4 A schematic diagram illustrating the automatic shunt protection technology for personal electric shock faults provided in an exemplary embodiment of this disclosure is shown. Figure 4 The diagram primarily illustrates the basic structure of a bypass parallel shunt grounding solid-state switch (also known as a resistor shunt switch or three-phase shunt switch). The shunt grounding solid-state switch 304 can include shunt branches connected to the ground between phase A, phase B, and phase C lines, respectively. Here, the shunt grounding solid-state switch can be referred to as a three-phase shunt switch, which can consist of three sets of single-phase shunt switches. Each set of single-phase shunt switches is a shunt branch connected to the ground of one phase line. Each shunt branch includes a solid-state switch unit and a current-limiting resistor connected in series.

[0039] When the three-phase power supply system is operating normally, the solid-state switch unit is in the open state, and the three-phase power supply system will not be affected. When a single-phase leakage fault occurs in a phase of the three-phase power supply system, the fault phase shunt leakage protection module 303 first identifies the fault phase (assuming it is phase A), and then immediately outputs a conduction signal to the solid-state switch unit of the shunt branch of phase A, causing it to quickly conduct, thereby connecting the corresponding current-limiting resistor between the phase A line and the ground, forming a ground shunt path, which significantly reduces the voltage of the fault phase and the electric shock current flowing through the human body.

[0040] Here, the fault phase shunt leakage protection module 303 utilizes the microsecond-level conduction characteristics of the solid-state switch unit to establish a low-impedance shunt channel within the first half-wave after a human body is electrocuted, diverting most of the fault current from the solid-state switch branch to the ground. At the same time, the current-limiting resistor clamps the current flowing through the human body to a safe threshold, achieving active protection that diverts rather than cuts off the current, significantly reducing electric shock injuries.

[0041] The circuit breaker trip control module 305 is signal-connected to the fault-phase shunt-type leakage current protection module 303. Simultaneously with the conduction of the solid-state switch unit corresponding to the fault, the fault-phase shunt-type leakage current protection module 303 sends a trip command to the circuit breaker trip control module 305. This module drives the circuit breaker at the incoming end of the power supply system to trip, completely cutting off the three-phase power supply and achieving proactive prevention of electric shock risks in the 10kV mine power supply system. The effect is that the shunt protection action limits the electric shock current within microseconds to milliseconds, while the mechanical tripping of the circuit breaker completely isolates the power supply within tens of milliseconds. The two work together in a sequence of first limiting current protection and then completely cutting off power, satisfying the speed requirement for electric shock protection while ensuring the faulty line is ultimately safely isolated. This avoids the secondary fault risks caused by long-term overheating of the current-limiting resistor or continuous conduction of the solid-state switch unit, significantly improving the personal safety protection level and operational reliability of the three-phase power supply system. Meanwhile, a solid-state switch unit is used to control the switching of the current-limiting resistor gas for grounding shunt, which has a fast switching speed and avoids the sparks generated during the switching process of contact switches.

[0042] According to the technical solution of the exemplary embodiments of this disclosure, a ground insulation resistance detection module is used to detect the ground insulation resistance of each phase line in a three-phase power supply system; a ground voltage detection module is used to detect the ground voltage of each phase line in a three-phase power supply system; a fault phase shunt leakage current protection module is signal-connected to the ground insulation resistance detection module and the ground voltage detection module respectively, and is used to determine the fault phase based on the ground voltage of each phase line when the ground insulation resistance meets the conditions for suspected electric shock; a shunt grounding solid-state switch includes shunt branches connected to the ground between phase A, phase B and phase C lines respectively, and each shunt branch includes a solid-state switch unit and a current-limiting resistor connected in series; a circuit breaker trip control module is signal-connected to the fault phase shunt leakage current protection module; wherein, after determining the fault phase, the fault phase shunt leakage current protection module is used to trigger the solid-state switch unit corresponding to the fault to conduct, so that the corresponding current-limiting resistor is connected between the fault phase and the ground to form a ground shunt path, and controls the circuit breaker to trip through the circuit breaker trip control module. The entire process forms a complete protection chain of "real-time monitoring → precise phase selection → rapid current shunting and limiting → reliable power disconnection". It not only meets the stringent requirements of personal electric shock protection for action speed and current limiting capability, but also avoids the risk of long-term current flow in solid-state switching units and current-limiting resistors by ultimately cutting off the power supply. It significantly improves the personal safety protection level and operational reliability of three-phase power supply systems, and solves the problems of easy exceedance of personal electric shock current, long fault current action time, and poor adaptability due to dependence on line conditions in related technologies.

[0043] In some embodiments, Figure 5 A circuit diagram of a ground insulation resistance detection module provided in an exemplary embodiment of this disclosure is shown. Figure 5 As shown, the ground insulation resistance detection module includes an additional DC detection power supply. E Three-phase reactor S k Zero-sequence reactor L k Sampling resistor R KD Current limiting resistor R 0 and filter capacitor C 1.

[0044] Among them, an additional DC detection power supply E The positive electrode is connected to the current-limiting resistor. R 0. Zero-sequence reactor L k Three-phase reactor S k Connected to a three-phase power supply line, the negative terminal is connected to a sampling resistor. R KD Grounding; Filter capacitor C 1 connected in parallel to the sampling resistorR KD Two ends. Three-phase reactor S k For neutral point connection devices, providing a path for DC detection signals; zero-sequence reactor L k Used to limit the interference of AC power frequency signals on DC detection circuits.

[0045] Figure 6 A circuit diagram of a ground voltage detection module provided in an exemplary embodiment of this disclosure is shown. Figure 6 As shown, the ground voltage detection module includes ground sampling capacitors respectively installed for phase A, phase B, and phase C lines. C y and current transformers C T .

[0046] Ground sampling capacitor for each phase line C y One end is connected to the phase line, and the other end is connected to the current transformer. C T On the primary side, current transformer C T The secondary output is connected to the signal conditioning circuit.

[0047] Figure 7 A circuit block diagram of phase-selective shunt leakage protection provided by an exemplary embodiment of this disclosure is shown. Figure 7 As shown, the fault phase shunt leakage protection module includes an insulation resistance detection signal conditioning circuit 701, a first analog-to-digital converter 702 (first A / D converter), a ground voltage detection signal conditioning circuit 703, a second analog-to-digital converter 704 (second A / D converter), an embedded microprocessor 705, a circuit breaker trip control circuit 706, and a solid-state shunt switch thyristor trigger control circuit 707.

[0048] The insulation resistance detection signal conditioning circuit 701 has its input terminal connected to the output terminal of the ground insulation resistance detection module, and is used to filter, amplify, and perform level matching processing on the ground insulation resistance detection signal; the first analog-to-digital converter 702 has its input terminal connected to the output terminal of the insulation resistance detection signal conditioning circuit 701, and is used to convert the analog ground insulation resistance detection signal into a digital signal; the ground voltage detection signal conditioning circuit 703 has its input terminal connected to the output terminal of the ground voltage detection module, and is used to filter, amplify, and perform level matching processing on the three-phase ground voltage detection signal; the second analog-to-digital converter 704 has its input terminal connected to the output terminal of the ground voltage detection signal conditioning circuit 703, and is used to convert the analog three-phase ground voltage detection signal into a digital signal. The first signal input terminal of the embedded microprocessor 705 is connected to the output terminal of the first analog-to-digital converter 702, the second signal input terminal is connected to the output terminal of the second analog-to-digital converter 704, the first control output terminal is connected to the circuit breaker tripping control circuit 706, and the second control output terminal is connected to the solid-state shunt switch thyristor triggering control circuit 707.

[0049] The embedded microprocessor 705 is used to receive the digitized insulation resistance to ground and voltage to ground, execute the preset fault judgment and phase selection algorithm, and when it is determined that the conditions for suspected electric shock are met, it outputs a trip command through the circuit breaker trip control circuit 706 and outputs the thyristor trigger pulse of the corresponding fault phase through the solid-state shunt switch thyristor trigger control circuit 707.

[0050] The embedded microprocessor 705 executes dual-channel parallel control outputs, simultaneously issuing circuit breaker trip commands and thyristor trigger pulses. The thyristor conduction (microseconds) is much faster than the circuit breaker action (tens of milliseconds), forming a two-level protection timing sequence of "first current shunting and limiting, then power-off and clearing," effectively filling the protection vacuum period during the mechanical action of the circuit breaker.

[0051] In some embodiments, the fault phase shunt leakage protection module is also used to determine that a single-phase leakage fault has occurred in the three-phase power supply system when the equivalent value of the insulation resistance to ground is less than the preset action setting value, and to determine that the conditions for suspected electric shock fault are met when the equivalent value of the insulation resistance to ground is within the range of suspected personal resistance; wherein, the equivalent value of the insulation resistance to ground is calculated based on the insulation resistance to ground of each phase line.

[0052] Specifically, the equivalent value of the insulation resistance to ground is calculated based on the insulation resistance to ground of each phase line. For example, the embedded microprocessor 705 uses an additional DC sensing power supply. E Get sampling resistor R KD Based on Ohm's law and the principle of series voltage division, the parallel equivalent value of the insulation resistance to ground of the three-phase line is derived from the voltage signal on the line, which is the equivalent value of the insulation resistance to ground.

[0053] The calculated equivalent value of the insulation resistance to ground is compared with a preset action setting value. If the equivalent value of the insulation resistance to ground is less than the preset action setting value, a single-phase leakage fault is determined to have occurred in the three-phase power supply system. Simultaneously, the calculated equivalent value of the insulation resistance to ground is compared with the range of suspected personal resistance. If the equivalent value of the insulation resistance to ground is within the range of suspected personal resistance, the conditions for a suspected electric shock fault are determined to be met. Here, the preset action setting value can be set according to the actual scenario, and this exemplary embodiment does not specifically limit it; the range of suspected personal resistance can be 1kΩ-3kΩ.

[0054] In some embodiments, the fault phase shunt leakage protection module is used to send a trigger pulse to the solid-state switch unit corresponding to the fault after the suspected electric shock fault condition is met, and to send a trip control signal to the circuit breaker trip control module. Among them, the conduction time of the corresponding shunt branch is earlier than the time when the circuit breaker completes the tripping.

[0055] Specifically, when the fault phase shunt-type leakage current protection module determines that the conditions for a suspected electric shock fault are met, the following two steps are performed simultaneously: (1) A trigger pulse is sent to the solid-state switch unit corresponding to the fault. After receiving the trigger pulse, the solid-state switch unit quickly turns on within a microsecond time (typical value ≤10μs), so that the shunt branch corresponding to the fault is immediately connected between the fault phase and the ground, forming a ground shunt path. (2) A trip control signal is sent to the circuit breaker trip control module. After receiving the command, the mechanical operating mechanism of the circuit breaker trip control module starts to operate. After experiencing the inherent operating time (including relay operating time, mechanism transmission time, and contact separation time, typical value 30ms~50ms), the moving and stationary contacts are completely separated, cutting off the power supply. The time from the occurrence of the leakage fault to the complete power cut-off is called the fault complete power-off time, which is generally greater than 50ms.

[0056] Because the conduction time of the thyristors in the solid-state switching unit is on the order of microseconds (approximately 10μs), while the inherent operating time of the circuit breaker in the circuit breaker trip control module is tens of milliseconds (approximately 30ms to 50ms), the conduction time of the shunt branch corresponding to the fault is much earlier than the time it takes for the circuit breaker to complete tripping (the former is about three orders of magnitude faster than the latter). That is, after a single-phase leakage fault suspected of causing electric shock, the shunt path can be established within 10ms to 20ms after the fault occurs, significantly reducing the current in the victim until the circuit breaker trips and the current completely disappears; while the circuit breaker takes about 50ms to complete tripping after the fault occurs.

[0057] The fault-phase shunt-type leakage current protection module achieves dual-path parallel control of "shunt + trip" without waiting for each other. Two control commands are issued simultaneously, avoiding the time loss caused by serial processing (executing one before the other). The embedded microprocessor can issue a trip command without waiting for thyristor conduction feedback, nor does it need to wait for the circuit breaker to complete its operation before initiating shunt, thus maximizing the parallel utilization of protection resources.

[0058] In some embodiments, the fault phase shunt leakage protection module is further used to determine the phase with the highest voltage to ground among phase A, phase B and phase C as the reference phase, and to determine the forward adjacent phase of the reference phase as the fault phase according to the positive sequence of phase A, phase B and phase C.

[0059] Specifically, Figure 8 A schematic diagram of a single-phase leakage fault in a neutral-point ungrounded system provided in an exemplary embodiment of this disclosure is shown. Figure 8 As shown, This represents the voltage to ground of phase A. This represents the voltage to ground of phase B line. This represents the voltage to ground of phase C. G A This indicates the insulation conductivity to ground of phase A line. G B This indicates the insulation conductivity to ground of phase B line. G C This indicates the insulation conductivity to ground of phase C. C A This represents the distributed capacitance of phase A to ground. C B This represents the distributed capacitance to ground of phase B. C C This represents the distributed capacitance to ground of phase C. Assume a single-phase leakage fault occurs in phase A of a three-phase power supply system, with a leakage resistance of... R d Meanwhile, the voltages to ground of phases A, B, and C are respectively denoted as... , , ,in, , ,Right now: (6) A single-phase leakage fault in phase A disrupts the three-phase symmetry of the system, affecting the neutral point. N Generate zero-sequence voltage After the fault, the three phases to ground voltages are as shown in equation (7).

[0060] (7) According to Kirchhoff's voltage and current laws, the following relationship can be written: (8) Simplifying, we obtain the zero-sequence voltage: (9) in: (10) Because the three-phase ground parameters of the power supply system are symmetrical and equal, that is: (11) At the same time, due to Then, equation (9) can be simplified to: (12) Further simplification yields: (13) The phase-to-ground voltages can be expressed as: (14) (15) (16) Figure 9 A voltage phasor diagram of a phase A fault provided in an exemplary embodiment of this disclosure is shown. Figure 9 As shown, the three-phase-to-ground voltage is represented by a phasor diagram. exist m 1~ n When the values ​​change between 1 and 1, let 1 be the case. and The included angle is θ 1, and The included angle is θ 2, and The included angle is θ 3. It can be seen that: , , .

[0061] When the grounding conductivity is infinite, it indicates that a metallic ground fault has occurred in phase A. , , When the grounding conductance is zero, phase A does not experience a fault. , ;when G d When the voltage is between ∞ and 0, and a ground fault occurs in phase A through a certain resistance value, according to the vector composition law, the voltage between phase C and ground is at its maximum at this time. .

[0062] Figure 10 A voltage phasor diagram of a phase B fault provided in an exemplary embodiment of this disclosure is shown. Figure 10 As shown, similarly, when phase B is grounded, That is, the voltage of phase A to ground is the highest. Similarly, when a ground fault occurs in phase C, the voltage of phase B is the highest.

[0063] From the above formula analysis and phasor relationship diagram analysis, the following conclusions can be drawn: When a single-phase leakage fault occurs in a neutral-point ungrounded system, the fault-phase shunt leakage protection module detects and compares the three-phase voltages to ground, taking the phase with the highest voltage to ground as the reference phase. Therefore, the single-phase leakage fault phase is determined to be the forward adjacent phase in the ABC phase cycle of the reference phase. For example, if the highest voltage to ground is detected for phase B, then the fault phase is phase C.

[0064] In some embodiments, each solid-state switching unit includes a first thyristor branch and a second thyristor branch arranged in reverse parallel, the first thyristor branch being used to conduct during the positive half-cycle of the AC voltage, and the second thyristor branch being used to conduct during the negative half-cycle of the AC voltage.

[0065] Specifically, Figure 11 A circuit diagram of a shunt grounding solid-state switch provided in an exemplary embodiment of this disclosure is shown. Figure 11 As shown, each phase solid-state switch unit ( T 1. T 2. T 3) Includes a first thyristor branch and a second thyristor branch configured in reverse parallel. After the two thyristor branches are connected in reverse parallel, they are connected in series in one phase line and a current-limiting resistor. R p And between the earth and the sky.

[0066] A single thyristor can only conduct in one direction and cannot operate during the other half of the AC voltage cycle. By adopting a reverse parallel structure, the positive half-cycle is conducted by the first thyristor branch, and the negative half-cycle is conducted by the second thyristor branch. The two branches together cover the complete AC cycle, ensuring that a continuous and uninterrupted shunt path to ground is provided for the fault current regardless of what phase of the voltage waveform the fault occurs in, thus avoiding protection blind spots.

[0067] In some embodiments, both the first thyristor branch and the second thyristor branch include at least two high-voltage thyristors connected in series, and the gate of the high-voltage thyristor is connected to the signal of the solid-state shunt switch thyristor trigger control circuit of the fault phase shunt leakage current protection module.

[0068] Specifically, the key component of the shunt grounding solid-state switch is a high-voltage thyristor. Both the first and second thyristor branches include at least two high-voltage thyristors connected in series. For example, each thyristor branch can use two thyristors with a reverse withstand voltage of 8000V connected in series to ensure the withstand voltage safety of the components, allowing them to jointly withstand the line voltage of a 10kV system.

[0069] Taking phase A as an example, the first thyristor branch consists of two high-voltage thyristors connected in series. Its anode is connected to the phase A line, and its cathode is connected to the current-limiting resistor. R p One end is connected; the second thyristor branch is also composed of two high-voltage thyristors connected in series, but their connection direction is opposite, that is, the anode is connected to the current-limiting resistor. R p The cathode is connected to the A-phase line. After the two thyristor branches are connected in reverse parallel, the entire assembly is connected in series with the A-phase line and the current-limiting resistor. R pBetween the earth and the sky. High-voltage thyristors and their series voltage divider technology are mature, inexpensive, highly reliable, and low-cost.

[0070] The gates of the first and second thyristor branches are respectively connected to the solid-state shunt switch thyristor trigger control circuit of the fault-phase shunt leakage current protection module. When a suspected electric shock fault is detected in phase A, the embedded microprocessor can send trigger pulses to the corresponding thyristor branches in a time-division manner based on the phase information of the current AC voltage: when the AC voltage of phase A is in the positive half-cycle, a trigger pulse is sent to the gate of the first thyristor branch to turn it on; when the AC voltage of phase A is in the negative half-cycle, a trigger pulse is sent to the gate of the second thyristor branch to turn it on. In this way, the two thyristor branches are turned on alternately, jointly completing the current shunting task between the fault phase and ground throughout the entire AC cycle.

[0071] In some embodiments, the current-limiting resistor is used to reduce the voltage to ground of the faulty phase to a preset safe range when the solid-state switching unit of the corresponding phase is turned on, and to limit the interphase short-circuit current when at least two phase shunt branches are mis-turned on; the resistance of the current-limiting resistor is 10Ω.

[0072] Specifically, the assessment of personal electric shock safety is very complex, and is generally based on the industrial frequency safe current of 30mA and the product of current and time of 30mAs. A more detailed and accurate assessment is conducted in accordance with GB / T 13870.1-2008 / IEC / TS 60479-1:2005 "Effects of current on buman beings and livestock Part 1, General aspects (IEC / TS 60479-1.2005, IT)".

[0073] Based on statistical calculations of animal experimental results, the probability of developing fibrillation is 5% when the duration of the electric shock is less than 0.1s and the current is greater than 500mA, following the current path from the left hand to both feet; and when the duration of the electric shock is less than 50ms and the current is greater than 2000mA, the probability of developing fibrillation is more than 50%.

[0074] Assuming a human body resistance of 1kΩ, calculate the electric shock current. Discuss the effects of shunt grounding resistance (i.e., current-limiting resistor) of 1Ω and 10Ω on the current flowing through the human body. Discuss the shunt switch turning on 10ms and 20ms after the electric shock fault, and the high-explosive switch tripping within 50ms after the fault. Conduct a safety assessment according to GB / T13870.1-2008.

[0075] Assume that a personal electric shock fault occurs in phase A at t=0.2s, and the protection device closes the phase A shunt grounding protection switch (i.e., solid-state switch unit) at t=0.22s. That is, the time for the shunt grounding resistor to be connected after the fault is t0=20ms; assume the bypass shunt grounding resistor (i.e., current-limiting resistor). R p The current waveform flowing through the human body is 10Ω, as shown below. Figure 12 As shown. Figure 12 The diagram illustrates a waveform of the human current in a neutral-point ungrounded system provided by an exemplary embodiment of this disclosure.

[0076] Depend on Figure 12 It can be seen that during an electric shock accident, the peak current flowing through the human body reaches as high as 7.7A, with an effective value of approximately 5.4A. After the shunt switch is turned on and phase A is grounded through a 10Ω resistor, the voltage of phase A to ground drops to 54V, causing the current in the human body to decrease rapidly, with an effective value of approximately 54mA. This significantly reduces the probability of electric shock injury or death, providing a certain degree of protection for personal safety. Here, the preset safe range for the voltage to ground mentioned above can be a voltage to ground less than or equal to 54V.

[0077] If the fault-phase shunt-type leakage current protection module can quickly determine a single-phase leakage fault, and activates the shunt grounding resistor (i.e., the current-limiting resistor) 10ms after a personal electric shock accident (t0=10ms), and disconnects the power switch within 50ms after the electric shock, the current waveform flowing through the human body is as follows: Figure 13 As shown. Figure 13 A waveform diagram of the human current in another neutral-point ungrounded system provided by an exemplary embodiment of this disclosure is shown.

[0078] Depend on Figure 13 It can be seen that the rapid action of the solid-state switching unit is very important, and the earlier the shunt grounding resistor is put into operation after an electric shock accident, the more obvious its effect in preventing electric shock injuries.

[0079] To prevent two-phase or three-phase short-circuit faults caused by false triggering of solid-state switching units in the shunt branch, a bypass current-limiting resistor with a resistance value of 10Ω is connected in series between each phase solid-state switching unit and ground. Even if two phase solid-state switching units are falsely triggered (false conduction), the line voltage applied across the two 10Ω series current-limiting resistors will only result in a current of 500A, which has a very small impact on the system.

[0080] In some embodiments, the circuit breaker trip control module includes a trip control relay, which is used to control the circuit breaker to trip.

[0081] Specifically, the input terminal of the trip control relay can be connected to the output terminal of the solid-state shunt switch thyristor trigger control circuit in the fault phase shunt leakage current protection module, and its output terminal is connected to the trip coil of the circuit breaker.

[0082] When the fault-phase shunt-type residual current protection module determines that the conditions for a suspected electric shock fault are met, the embedded microprocessor outputs a high-level trip command signal through the solid-state shunt switch thyristor trigger control circuit. This signal energizes the trip control relay coil, closing the relay contacts and thus connecting the power supply circuit of the circuit breaker trip coil. After the trip coil is energized, it drives the circuit breaker operating mechanism to actuate, separating the moving and stationary contacts of the circuit breaker and ultimately cutting off the power supply.

[0083] The trip control relay can be a fast intermediate relay, whose inherent operating time (from coil energization to contact closure) is usually 5ms to 10ms, to ensure that the total delay from the microprocessor issuing the instruction to the circuit breaker starting to trip is minimized.

[0084] This disclosure also provides a method for protecting a person from electric shock in a three-phase power supply system with automatic phase selection and current shunting, which is applied to the aforementioned automatic phase selection and current shunting method for protecting a person from electric shock in a three-phase power supply system. Figure 14 A flowchart illustrating an exemplary embodiment of this disclosure shows a method for protecting a person from electric shock in a three-phase power supply system with automatic phase selection and current shunting. Figure 14 As shown, the method for protecting against electric shock in this three-phase power supply system with automatic phase selection and current shunting includes: S1401, Ground insulation resistance detection module, detects the ground insulation resistance of a three-phase power supply system; S1402, Ground voltage detection module detects the ground voltage of each phase line in a three-phase power supply system; S1403, the fault phase shunt leakage protection module determines the fault phase based on the ground voltage of each phase line when the ground insulation resistance meets the conditions for suspected electric shock. After determining the fault phase, it triggers the corresponding solid-state switch unit to conduct, so that the corresponding current-limiting resistor is connected between the fault phase and the ground to form a ground shunt path, and controls the circuit breaker to trip through the circuit breaker trip control module.

[0085] Specifically, such as Figure 3 As shown, the ground insulation resistance detection module 301 monitors the ground insulation resistance between each phase of the three-phase power supply system and the ground in real time, and transmits the ground insulation resistance to the fault phase shunt leakage current protection module 303. The ground voltage detection module 302 monitors the ground voltage of each of the A-phase, B-phase, and C-phase lines in the three-phase power supply system in real time, and sends the ground voltage to the fault phase shunt leakage current protection module 303.

[0086] The fault-phase shunt-type leakage current protection module 303 is internally configured with suspected electric shock fault conditions and fault phase judgment conditions. The fault-phase shunt-type leakage current protection module 303 can determine whether the insulation resistance to ground meets the suspected electric shock fault conditions. If the insulation resistance to ground meets the suspected electric shock fault conditions, based on the voltage to ground of each phase line and the judgment conditions for the fault phase, it determines the fault phase in phases A, B, and C, thus achieving automatic judgment of the fault phase where electric shock has occurred.

[0087] When the three-phase power supply system is operating normally, the solid-state switch unit is in the open state, and the three-phase power supply system will not be affected. When a single-phase leakage fault occurs in a phase of the three-phase power supply system, the fault phase shunt leakage protection module 303 first identifies the fault phase (assuming it is phase A), and then immediately outputs a conduction signal to the solid-state switch unit of the shunt branch of phase A, causing it to quickly conduct, thereby connecting the corresponding current-limiting resistor between the phase A line and the ground, forming a ground shunt path, which significantly reduces the voltage of the fault phase and the electric shock current flowing through the human body.

[0088] Here, the fault phase shunt leakage protection module 303 utilizes the microsecond-level conduction characteristics of the solid-state switch unit to establish a low-impedance shunt channel within the first half-wave after a human body is electrocuted, diverting most of the fault current from the solid-state switch branch to the ground. At the same time, the current-limiting resistor clamps the current flowing through the human body to a safe threshold, achieving active protection that diverts rather than cuts off the current, significantly reducing electric shock injuries.

[0089] Simultaneously with the activation of the corresponding solid-state switch unit, the fault-phase shunt leakage current protection module 303 sends a trip command to the circuit breaker trip control module 305. This module drives the circuit breaker at the incoming end of the power supply system to trip, completely cutting off the three-phase power supply and achieving proactive prevention and control of electric shock risks in the 10kV mine power supply system. The effect is that the shunt protection action limits the electric shock current within microseconds to milliseconds, while the mechanical trip of the circuit breaker completely isolates the power supply within tens of milliseconds. The two work together in a sequence of first limiting current and then completely cutting off power, satisfying the speed requirement for electric shock protection while ensuring the faulty line is ultimately safely isolated. This avoids the risk of secondary faults caused by long-term overheating of the current-limiting resistor or continuous activation of the solid-state switch unit, significantly improving the personal safety protection level and operational reliability of the three-phase power supply system. Furthermore, the use of a solid-state switch unit to control the switching of the grounding shunt current-limiting resistor ensures fast switching speeds and avoids sparks generated during the switching process of contact switches.

[0090] According to the technical solution of the exemplary embodiments of this disclosure, the ground insulation resistance detection module detects the ground insulation resistance of the three-phase power supply system; the ground voltage detection module detects the ground voltage of each phase line in the three-phase power supply system; the fault phase shunt leakage current protection module determines the fault phase based on the ground voltage of each phase line when the ground insulation resistance meets the conditions for suspected electric shock; after determining the fault phase, the corresponding solid-state switch unit is triggered to conduct, so that the corresponding current-limiting resistor is connected between the fault phase and the ground to form a ground shunt path, and the circuit breaker tripping control module controls the circuit breaker to trip. The whole process forms a complete protection chain of "real-time monitoring → accurate phase selection → rapid current shunt and current limiting → reliable power disconnection", which not only meets the stringent requirements of electric shock protection for action speed and current limiting capability, but also avoids the risk of long-term current flow of solid-state switch units and current-limiting resistors by finally cutting off the power supply, significantly improving the level of personal safety protection and operational reliability of the three-phase power supply system, and solving the problems of easy exceedance of electric shock current, long fault current action time, and poor adaptability due to dependence on line conditions in related technologies.

[0091] The above description is merely an illustration of some embodiments of this disclosure and the technical principles employed. Those skilled in the art should understand that the scope of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features disclosed in this disclosure that have similar functions.

[0092] While specific embodiments of this disclosure have been described in detail by way of example, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this disclosure. The scope of this disclosure is defined by the appended claims.

Claims

1. An automatic phase-selective current-shunting three-phase power supply system electric shock protection device, wherein the three-phase power supply system uses an isolation transformer with a neutral point ungrounded on the secondary side, characterized in that, The device includes: The ground insulation resistance detection module is used to detect the ground insulation resistance of each phase line in the three-phase power supply system. A voltage-to-ground detection module is used to detect the voltage-to-ground of each phase line in the three-phase power supply system; The fault phase shunt leakage current protection module is connected to the ground insulation resistance detection module and the ground voltage detection module respectively, and is used to determine the fault phase based on the ground voltage of each phase line when the ground insulation resistance meets the suspected electric shock fault conditions. The shunt grounding solid-state switch includes shunt branches respectively connected between phase A line, phase B line and phase C line and the ground, and each shunt branch includes a solid-state switch unit and a current-limiting resistor arranged in series. The circuit breaker tripping control module is signal-connected to the fault phase shunt leakage current protection module; The fault phase shunt leakage protection module is used to trigger the solid-state switch unit corresponding to the fault to conduct after the fault phase is determined, so that the corresponding current limiting resistor is connected between the fault phase and the ground to form a ground shunt path, and the circuit breaker tripping control module controls the circuit breaker to trip.

2. The apparatus according to claim 1, characterized in that, The ground insulation resistance detection module includes an additional DC detection power supply, a three-phase reactor, a zero-sequence reactor, a sampling resistor, a current-limiting resistor, and a filter capacitor; The ground voltage detection module includes ground sampling capacitors and current transformers respectively installed corresponding to the A-phase line, the B-phase line and the C-phase line; The fault phase shunt leakage protection module includes an insulation resistance detection signal conditioning circuit, a first analog-to-digital converter, a ground voltage detection signal conditioning circuit, a second analog-to-digital converter, an embedded microprocessor, a circuit breaker tripping control circuit, and a solid-state shunt switch thyristor triggering control circuit.

3. The apparatus according to claim 1, characterized in that, The fault phase shunt leakage protection module is also used to determine that a single-phase leakage fault has occurred in the three-phase power supply system when the equivalent value of the insulation resistance to ground is less than the preset action setting value, and to determine that the suspected electric shock fault condition is met when the equivalent value of the insulation resistance to ground is within the range of suspected personal resistance; wherein, the equivalent value of the insulation resistance to ground is calculated based on the insulation resistance to ground of each phase line.

4. The apparatus according to claim 1, characterized in that, The fault phase shunt leakage protection module is used to send a trigger pulse to the solid-state switch unit corresponding to the fault and send a trip control signal to the circuit breaker trip control module after the suspected electric shock fault condition is met. Wherein, the conduction time of the shunt branch corresponding to the fault is earlier than the time when the circuit breaker completes tripping.

5. The apparatus according to claim 1, characterized in that, The fault phase shunt leakage protection module is also used to determine the phase with the highest voltage to ground among phase A, phase B and phase C as the reference phase, and to determine the forward adjacent phase of the reference phase as the fault phase according to the positive sequence of phase A, phase B and phase C.

6. The apparatus according to claim 1, characterized in that, Each of the solid-state switching units includes a first thyristor branch and a second thyristor branch connected in reverse parallel. The first thyristor branch is used to conduct during the positive half-cycle of the AC voltage, and the second thyristor branch is used to conduct during the negative half-cycle of the AC voltage.

7. The apparatus according to claim 6, characterized in that, Both the first thyristor branch and the second thyristor branch include at least two high-voltage thyristors connected in series. The gate of the high-voltage thyristor is connected to the signal of the solid-state shunt switch thyristor trigger control circuit of the fault phase shunt leakage current protection module.

8. The apparatus according to claim 1, characterized in that, The current-limiting resistor is used to reduce the voltage to ground of the faulty phase to a preset safe range when the solid-state switch unit of the corresponding phase is turned on, and to limit the inter-phase short-circuit current when at least two phase shunt branches are mis-turned on; the resistance of the current-limiting resistor is 10Ω.

9. The apparatus according to any one of claims 1 to 8, characterized in that, The circuit breaker trip control module includes a trip control relay, which is used to control the circuit breaker to trip.

10. A method for protecting a person from electric shock in a three-phase power supply system with automatic phase selection and current shunting, applied to the automatic phase selection and current shunting three-phase power supply system electric shock protection device as described in any one of claims 1 to 9, characterized in that, The method includes: The insulation resistance to ground detection module detects the insulation resistance to ground of each phase line in the three-phase power supply system; The voltage-to-ground detection module detects the voltage-to-ground of each phase line in the three-phase power supply system; When the insulation resistance to ground meets the conditions for suspected electric shock, the fault phase shunt leakage protection module determines the fault phase based on the voltage to ground of each phase line. After determining the fault phase, it triggers the solid-state switch unit corresponding to the fault to conduct, so that the corresponding current-limiting resistor is connected between the fault phase and the ground to form a shunt path to ground, and controls the circuit breaker to trip through the circuit breaker trip control module.

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