A distributed ground fault line selection system and method based on intelligent grounding device

Abstract

The present application discloses a distributed ground fault line selection system and method based on an intelligent grounding device, which relates to the field of ground fault processing and includes a circuit breaker; a current transformer 1 for detecting the zero-sequence current value of the corresponding line; a preprocessor for collecting the zero-sequence current value signal of the current transformer 1 and transmitting an alarm signal to the intelligent grounding device and a monitoring terminal; an intelligent grounding device for receiving the alarm signal, transferring the ground fault current, and determining the phase where the ground fault is located; a monitoring terminal for receiving the alarm signal and controlling the circuit breaker to open; the intelligent grounding device includes a controller, a switch 1 and a phase switch, and a current limiting resistor, wherein the switches in the phase switch correspond to the three-phase line respectively, and the switch 1 is connected in parallel to the current limiting resistor; the intelligent grounding device also includes a three-phase switch and a grounding transformer, wherein the input end of the three-phase switch is connected to the three-phase line, and the output end of the grounding transformer is grounded. The present application has the effect of reducing the power consumed by the monitoring terminal.

Description

Technical Field

[0001] The present application relates to the technical field of ground fault processing, and in particular to a distributed ground fault line selection system and method based on an intelligent grounding device. Background Art

[0002] Single-phase grounding fault is one of the more common circuit faults in the power grid distribution system. The causes of single-phase grounding fault include insulator breakdown failure, accidental contact with animals and plants, line disconnection, etc. The occurrence of single-phase grounding fault may cause the following hazards: damage to substation equipment, reduce the stability and reliability of regional power grid operation, and endanger the personal safety of surrounding residents.

[0003] The distribution switch monitoring terminal (hereinafter referred to as the "monitoring terminal") features remote control, telemetering, telesignaling, and line fault detection. It can communicate with the distribution automation master station, providing information on distribution system operation, various parameters, and monitoring and control. One of the monitoring terminal's primary functions is to detect single-phase grounding faults. If the monitoring terminal identifies a single-phase grounding fault as a permanent fault, it controls the pole-mounted circuit breaker (hereinafter referred to as the "circuit breaker") on the faulty line to trip, minimizing the risk of damage to electrical equipment and personnel.

[0004] However, after the monitoring terminal detects a single-phase grounding fault, it needs to first perform a fault type judgment, that is, first determine whether the single-phase grounding fault is a transient fault or a permanent fault. If it is a transient fault, the monitoring terminal will automatically re-control the circuit breaker corresponding to the faulty line to close. If it is a permanent fault, the circuit breaker corresponding to the faulty line needs to be disconnected for fault detection and line maintenance.

[0005] After the monitoring terminal is put into operation and detects a single-phase grounding fault, it needs to identify whether the fault type is a transient fault or a permanent fault. This puts the monitoring terminal in a high-energy consumption state. This not only increases the power consumption of the monitoring terminal (monitoring terminals are usually equipped with a backup power supply to prevent the monitoring terminal from losing power and being unable to control the closing and opening of the circuit breaker), but also shortens the service life of the monitoring terminal. Summary of the Invention

[0006] In order to reduce the power consumed by the monitoring terminal, the present application provides a distributed ground fault line selection system and method based on an intelligent grounding device.

[0007] In a first aspect, the present application provides a distributed ground fault line selection system based on an intelligent grounding device, which adopts the following technical solutions:

[0008] A distributed ground fault line selection system based on an intelligent grounding device includes a circuit breaker for controlling the closing and opening of corresponding lines;

[0009] A current transformer 1 for detecting the zero-sequence current value of the corresponding line;

[0010] A preprocessor that collects the zero-sequence current value signal of current transformer 1 and transmits an alarm signal to the intelligent grounding device and the monitoring terminal;

[0011] An intelligent grounding device that receives alarm signals, diverts ground fault current, and determines the phase where the ground fault is located;

[0012] Monitoring terminal that receives alarm signals and controls circuit breaker opening;

[0013] The intelligent grounding device includes a controller, a switch 1, a phase-splitting switch and a current-limiting resistor connected in series. The switches in the phase-splitting switch correspond to the three-phase lines respectively. The switch 1 is connected in parallel to the current-limiting resistor. A current transformer 2 is provided on the grounding line of the current-limiting resistor.

[0014] The intelligent grounding device also includes a three-phase switch and a grounding transformer connected in series. The input end of the three-phase switch is connected to the three-phase line, and the output end of the grounding transformer is grounded.

[0015] The controller is used to collect the three-phase line voltage value, zero-sequence voltage value and current value of the current-limiting resistor, and control the closing and opening of the phase switch, switch one and the three-phase switch.

[0016] Since the type of single-phase grounding fault (permanent fault or transient fault) has been determined by the intelligent grounding device (the fault type determination process is described in detail in the specific implementation method), the monitoring terminal only needs to control the circuit breaker corresponding to the line where the permanent single-phase grounding fault is located based on the fault line information output by the intelligent grounding device. Therefore, the monitoring terminal does not need to be in a high power consumption state all the time, which effectively reduces the power consumption of the monitoring terminal. In particular, when the monitoring terminal is powered by a backup power supply, the effect of reducing the energy consumption of the monitoring terminal is particularly important.

[0017] In addition, since the operating time of the monitoring terminal in a high power consumption state is shortened, the operating load of the equipment is reduced, thereby extending the service life of the equipment.

[0018] In a preferred example, the present application can be further configured such that the tripping time of the circuit breaker is consistent with the time when the fault line selection information of the intelligent grounding device is sent.

[0019] Through the above technical solution, the intelligent grounding device determines the line where the ground fault is located and sends information about the fault line. At the same time, the intelligent feeder terminal immediately controls the corresponding circuit breaker to open the switch, cutting off the fault line or the section where the fault line is located, thereby shortening the time the fault line is energized and running, minimizing the safety risks caused by the ground fault, and also buying maintenance time for maintenance personnel.

[0020] In a second aspect, based on the above-mentioned distributed ground fault line selection system based on an intelligent grounding device, the present application further provides a distributed ground fault line selection method based on an intelligent grounding device, which adopts the following technical solution:

[0021] A distributed ground fault line selection method based on an intelligent grounding device comprises:

[0022] The preprocessor obtains the abnormal current information of the current transformer 1 and transmits the abnormal current information to the monitoring terminal and the intelligent grounding device;

[0023] The intelligent grounding device controls the closing of the phase switch according to the abnormal current information;

[0024] If the fault disappears, the intelligent grounding device is shut down; if the fault persists, the switch 1 is closed;

[0025] Closing the three-phase switch, switching on and off the grounding transformer, and opening the phase switch and switch 1;

[0026] Based on the current fluctuation information of each current transformer, the fault line is determined, the fault line information is generated, and reported to the backend;

[0027] The monitoring terminal controls the opening of the circuit breaker of the line where the fault occurs.

[0028] Through the above technical solution, the technical effects of this technical solution are detailed in detail, see the specific implementation method.

[0029] In a preferred example, the present application may be further configured such that, after the monitoring terminal controls the circuit breaker of the faulty line to open, the following steps are further included:

[0030] Obtain driving power information of the monitoring terminal;

[0031] Based on the driving power information, identifying whether the driving power of the monitoring terminal comes from a backup power supply or a power grid; if the driving power comes from the backup power supply, obtaining the remaining power information of the monitoring terminal;

[0032] Based on the remaining power information, dividing the remaining power into a plurality of power gradients according to preset power percentages;

[0033] The number of circuit breakers controlled by the monitoring terminal is obtained, and when the remaining power of the backup power supply decreases in a power gradient, the number of circuit breakers monitored simultaneously is reduced.

[0034] Through the above technical solution, based on the driving power information, if the analysis shows that the driving power comes from the backup power supply, the remaining power information of the monitoring terminal is obtained, that is, the remaining power information of the backup power supply, and the remaining power information includes information such as the percentage of the remaining power.

[0035] Then, according to the preset power percentage, the remaining power is divided into multiple power gradients. For example, when the power reaches 50%, it corresponds to a certain power gradient, when the power reaches 40%, it corresponds to another power gradient, and so on.

[0036] When the power gradient decreases (for example, from 50% to 40%), the number of circuit breakers monitored simultaneously is reduced. It's important to emphasize that this doesn't mean reducing the number of circuit breakers monitored, but rather the number of circuit breakers monitored simultaneously. For example, a monitoring terminal monitors nine circuit breakers, numbered 1 through 9. A ground fault has occurred on breaker 9. Therefore, excluding the circuit breaker with the ground fault, the monitoring terminal needs to monitor the remaining eight circuit breakers, numbered 1 through 8.

[0037] Before the power gradient decreases, circuit breakers 1 to 8 need to be monitored simultaneously. If the power gradient decreases by one gradient at this time, circuit breakers 1 to 7 are monitored in the first time period, and in the next time period, circuit breakers 2 to 8 are monitored. In the next time period, circuit breakers 3 to 8 and 1 are monitored, and so on, and then circuit breakers 4 to 8 and 1 and 2 are monitored.

[0038] That is to say, when the power gradient decreases, the number of circuit breakers monitored simultaneously is reduced to extend the usage time of the backup power supply of the monitoring terminal, so that the monitoring terminal can obtain a longer battery life with the support of the backup power supply.

[0039] In a preferred example, the present application may be further configured such that reducing the number of circuit breakers monitored simultaneously includes:

[0040] Multiple circuit breakers controlled by the monitoring terminal, excluding those that have experienced ground faults, are virtualized to form a monitoring target, where each unit in the monitoring target corresponds to a different circuit breaker;

[0041] Calculate the number of effective units based on the number of circuit breakers controlled by the monitoring terminal, excluding those that have experienced ground faults, and the number of circuit breakers reduced by the power gradient decrease;

[0042] Based on the number of multiple effective units, a dynamic ring with a gap is formed;

[0043] Calculate the deflection angle based on the number of circuit breakers controlled by the monitoring terminal and other than those where the ground fault has occurred;

[0044] The dynamic ring is rotated on the monitoring target at a deflection angle and a preset adjustment period. The unit where the dynamic ring and the monitoring target overlap is the monitoring unit, and the monitoring target unit corresponding to the gap in the dynamic ring is the non-monitoring unit.

[0045] Through the above technical solution, the technical effects and principles corresponding to this technical solution are elaborated in detail in the specific implementation methods and will not be repeated here.

[0046] In a preferred example, the present application may be further configured such that the deflection angle is calculated using the following formula:

[0047] ,

[0048] is the deflection angle, The number of circuit breakers controlled by the monitoring terminal that are not ground faults.

[0049] Through the above technical solution, That is, it corresponds to the 360 degrees of the entire circle angle. This corresponds to the number of circuit breakers controlled by the monitoring terminal that have not experienced ground faults. and The ratio of represents the center angle occupied by each monitoring target unit.

[0050] In a preferred example, the present application may be further configured such that the number of effective units is calculated using the following formula:

[0051] ,

[0052] is the number of effective units, The number of circuit breakers controlled by the monitoring terminal that have other than ground faults. The number of circuit breakers reduced due to the decrease in power gradient.

[0053] Through the above technical solution, The number of circuit breakers controlled by the monitoring terminal that have not experienced ground faults, is the number of circuit breakers reduced by the decrease of power gradient, and the difference between the two represents the number of effective units of the dynamic loop.

[0054] In summary, this application has the following beneficial technical effects:

[0055] 1. Since the type of single-phase grounding fault has been determined by the intelligent grounding device, the monitoring terminal can directly control the circuit breaker corresponding to the line where the permanent single-phase grounding fault occurs based on the fault line information output by the intelligent grounding device. Therefore, the monitoring terminal does not need to be in a high power consumption state all the time, which not only reduces the power consumption of the monitoring terminal but also extends the service life of the equipment.

[0056] 2. When the power gradient of the monitoring terminal decreases, the number of circuit breakers monitored simultaneously is reduced to extend the use time of the monitoring terminal's backup power supply, so that the monitoring terminal can obtain a longer battery life with the support of the backup power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application, mainly illustrating the installation positions of the pole-mounted circuit breaker and the intelligent feeder terminal.

[0058] Figure 2 1 is a circuit diagram of the intelligent grounding device in an embodiment of the present application.

[0059] Figure 3 It is a flow chart of the ground fault line selection method in an embodiment of the present application.

[0060] Figure 4 It is a flow chart of adjusting the number of circuit breakers to be monitored simultaneously in an embodiment of the present application.

[0061] Figure 5 It is a schematic diagram of the process of dynamic ring rotation in the embodiment of the present application.

[0062] Figure 6 It is a schematic diagram of the structure of the monitoring target in the embodiment of the present application.

[0063] Figure 7 It is a structural diagram of the dynamic ring in the embodiment of the present application.

[0064] Figure 8 It is a schematic diagram of the structure of the overlapping dynamic ring and monitoring target in the embodiment of the present application.

[0065] Description of reference numerals:

[0066] 1. Circuit breaker; 2. Monitoring terminal; 21. Backup power supply; 3. Intelligent grounding device; 31. Switch 1; 32. Phase switch; 33. Current limiting resistor; 331. Current transformer 2; 34. Three-phase switch; 35. Grounding transformer; 36. Pre-switch; 4. Monitoring target; 5. Dynamic ring; 51. Gap. DETAILED DESCRIPTION

[0067] The following is combined with Figure 1 -Attached Figure 8 This application is described in further detail.

[0068] The embodiments of the present application disclose a distributed grounding fault line selection system based on an intelligent grounding device, and based on the system, also disclose a grounding fault line selection method.

[0069] Refer to the attached Figure 1 and attached Figure 2As shown, a distributed ground fault line selection system based on an intelligent grounding device 3 includes a circuit breaker 1, a current transformer 1, a preprocessor, an intelligent grounding device 3, and a monitoring terminal 2.

[0070] Circuit breaker 1 controls the closing and opening of the corresponding line. Current transformer 1 detects the zero-sequence current of the corresponding line. The preprocessor collects the zero-sequence current signal from current transformer 1 and transmits an alarm signal to intelligent grounding device 3 and monitoring terminal 2. Intelligent grounding device 3 receives the alarm signal, transfers the ground fault current, and determines the phase of the ground fault. Monitoring terminal 2 receives the alarm signal and controls the closing and opening of circuit breaker 1.

[0071] Refer to the attached Figure 1 and attached Figure 2 As shown, the intelligent grounding device 3 includes a pre-switch 36, a controller, a switch 1 31, a phase switch 32, and a current limiting resistor 33. The switches in the phase switch 32 correspond to the three-phase lines respectively, and three switches are provided in the phase switch 32, which are respectively used to control the closing and opening of the corresponding phase lines. The phase switch 32 is connected in series to the current limiting resistor 33, and the switch 1 31 is connected in parallel to the current limiting resistor 33. A current transformer 2 331 is provided on the grounding line of the current limiting resistor 33.

[0072] Refer to the attached Figure 1 and attached Figure 2 As shown, the intelligent grounding device 3 further includes a three-phase switch 34 and a grounding transformer 35 connected in series. The input end of the three-phase switch 34 is connected to the three-phase line, and the output end of the grounding transformer 35 is grounded.

[0073] The controller is used to collect the three-phase line voltage value, the zero-sequence voltage value and the current value of the current limiting resistor 33, and control the closing and opening of the phase switch 32, the switch 1 31 and the three-phase switch 34.

[0074] The front switch 36 is used to control the switching of the intelligent grounding device 3 .

[0075] When the power supply line of this system is in stable operation, the vector sum of the three-phase current is zero. However, when a ground fault occurs in one phase of the three-phase line (i.e., a single-phase ground fault), the vector balance is broken, that is, the vector sum of the currents in the three-phase line is not zero. The current transformer 1 can detect the zero-sequence current, thereby forming a zero-sequence current signal. Then, the preprocessor collects and converts the zero-sequence current signal and transmits it to the monitoring terminal 2 and the intelligent grounding device 3.

[0076] After the alarm signal is received by the intelligent grounding device 3, the three switches in the phase switch 32 are first closed one by one. At this time, switch 1 31 is open, and current transformer 2 331 determines whether the closing phase is correct by sensing the current change of the current limiting resistor 33. Until the closing phase is correct, the phase switches 32 are stopped from closing one by one.

[0077] If closing each of the three switches in three-phase switch 34 one by one can eliminate the single-phase ground fault, it indicates that the single-phase ground fault is a transient fault. If closing each of the three switches 34 one by one cannot eliminate the single-phase ground fault, it indicates that the single-phase ground fault is a permanent fault. If the fault type is permanent, closing switch 1 31 again will short-circuit current-limiting resistor 33. The fault phase voltage will drop to zero, the non-fault phase voltage will rise to the line voltage, and the three-phase voltage will remain unchanged, allowing the power grid system to continue operating for a period of time. During this period, the permanent fault can be investigated and repaired.

[0078] After switch 1 31 is closed, three-phase switch 34 is closed, grounding transformer 35 is switched on, and then phase switch 32 and switch 1 31 are disconnected. When a single-phase grounding fault occurs, the zero-sequence voltage rises sharply in a short period of time. After grounding transformer 35 is switched on, the zero-sequence voltage drops significantly, and the zero-sequence voltage waveform shows a concave change. The zero-sequence current waveforms of the fault line and the non-fault line show a significant difference, that is, the zero-sequence current of the fault branch increases, while the zero-sequence current of the non-fault branch decreases. Based on this feature, the non-fault line and the fault line are distinguished, the line where the grounding fault is located is determined, and the fault line information (i.e., information including the specific line where the fault is located) is generated.

[0079] Since the type of single-phase grounding fault (permanent fault or transient fault) has been determined by the intelligent grounding device 3, the monitoring terminal 2 only needs to directly control the circuit breaker 1 corresponding to the line where the permanent single-phase grounding fault is located to open according to the fault line information output by the intelligent grounding device 3. Therefore, the monitoring terminal 2 does not need to be in a high power consumption state all the time, which effectively reduces the power consumption of the monitoring terminal 2. In particular, when the monitoring terminal 2 is powered by the backup power supply 21, the effect of reducing the energy consumption of the monitoring terminal 2 is particularly important.

[0080] In addition, since the operating time of the monitoring terminal 2 in the high power consumption state is shortened, the operating load of the equipment is reduced, thereby extending the service life of the equipment.

[0081] The tripping time of circuit breaker 1 coincides with the issuance of fault line selection information by intelligent grounding device 3. After intelligent grounding device 3 determines the line where the ground fault is located and issues the information, the intelligent feeder terminal immediately controls the corresponding circuit breaker 1 to trip, disconnecting the faulty line or the section where the faulty line is located. This shortens the live operation time of the faulty line, minimizes the safety risks caused by the ground fault, and also buys maintenance personnel more time.

[0082] Refer to the attached Figure 3 As shown, based on the above-mentioned distributed ground fault line selection system based on the intelligent grounding device 3, the present application also provides a distributed ground fault line selection method based on the intelligent grounding device 3, which adopts the following technical solutions:

[0083] A distributed ground fault line selection method based on an intelligent grounding device 3 includes:

[0084] S101 : A preprocessor obtains abnormal current information of a current transformer 1 and transmits the abnormal current information to a monitoring terminal 2 and an intelligent grounding device 3 .

[0085] During implementation, when a single-phase grounding fault occurs in one phase of a three-phase line, the vector balance of the three-phase current is broken. At this time, the current vector sum of the three-phase line is not zero, and the current transformer 1 can detect the zero-sequence current, thereby forming a zero-sequence current signal. Then, the preprocessor collects and converts the zero-sequence current signal and transmits it to the monitoring terminal 2 and the intelligent grounding device 3.

[0086] S102 : The intelligent grounding device 3 controls the phase switch 32 to close according to the abnormal current information.

[0087] During implementation, after the alarm signal is received by the intelligent grounding device 3, the three switches in the phase switch 32 are closed one by one. At this time, switch 1 31 is open, and current transformer 2 331 determines whether the closing phase is correct by sensing the current change of the current limiting resistor 33. Until the closing phase is correct, the closing of the phase switch 32 one by one is stopped.

[0088] S103: If the fault disappears, the intelligent grounding device 3 exits; if the fault still exists, the switch 1 31 is closed.

[0089] In practice, if closing the three switches in the three-phase switch 34 one by one can eliminate the single-phase grounding fault, it means that the single-phase grounding fault is a transient fault. If closing the three-phase switch 34 one by one cannot eliminate the single-phase grounding fault, it means that the single-phase grounding fault is a permanent fault.

[0090] If the fault type is a permanent fault, switch 1 31 is closed again, short-circuiting the current-limiting resistor 33. The fault phase voltage becomes zero, and the non-fault phase voltage rises to the line voltage. The three-phase voltage remains unchanged, allowing the power grid system to continue operating for a period of time. During this period, the permanent fault can be checked and repaired.

[0091] S104 , close the three-phase switch 34 , switch on and off the grounding transformer 35 , and open the phase switch 32 and switch 1 31 .

[0092] S105. Based on the current fluctuation information of each current transformer 1, determine the line where the fault is located, generate fault line information, and report it to the backend.

[0093] During implementation, when a single-phase grounding fault occurs, the zero-sequence voltage will rise sharply in a short period of time. After the grounding transformer 35 is switched on and off, the zero-sequence voltage will drop significantly, and the zero-sequence voltage waveform will show a concave change. There will be obvious differences in the zero-sequence current waveforms between the fault line and the non-fault line. The zero-sequence current of the fault branch increases, and the zero-sequence current of the non-fault branch decreases. Based on this feature, the fault line and the non-fault line can be distinguished, the line where the grounding fault is located can be determined, the fault line information (i.e., information including the specific line where the fault is located) is generated, and the fault line information is reported to the monitoring terminal 2 and the background.

[0094] S106. Monitoring terminal 2 controls circuit breaker 1 of the faulty line to open.

[0095] During implementation, the monitoring terminal 2 receives the fault line information and can control the circuit breaker 1 of the fault line to open according to the fault line information, thereby isolating the line where the single-phase grounding fault is located, so that the operator can perform fault inspection and repair on the fault line.

[0096] Refer to the attached Figure 3 and attached Figure 4 As shown, in step S106, after the monitoring terminal 2 controls the circuit breaker 1 of the faulty line to open, the following steps are also included:

[0097] S201 : Acquire driving power information of monitoring terminal 2 .

[0098] In practice, the driving power information may include information such as whether the driving power of the monitoring terminal 2 comes from the grid system or the backup battery.

[0099] S202 , based on the driving power information, identifying whether the driving power of the monitoring terminal 2 comes from the backup power supply 21 or the power grid; if the driving power comes from the backup power supply 21 , obtaining the remaining power information of the monitoring terminal 2 .

[0100] In practice, based on the data analysis of the driving power information, if it is concluded that the driving power comes from the grid and the power acquisition is stable, there is no need to perform subsequent steps to reduce the operating power consumption of the monitoring terminal 2.

[0101] If it is determined that the driving power comes from the backup power supply 21 , the remaining power information of the monitoring terminal 2 is obtained, that is, the remaining power information of the backup power supply 21 , which includes information such as the percentage of the remaining power.

[0102] S203 : Based on the remaining power information, divide the remaining power into a plurality of power gradients according to preset power percentages.

[0103] In implementation, the remaining power is divided into multiple power gradients according to the preset power percentage. For example, the remaining power of the backup power supply 21 is 85%, and if the preset power percentage is 10%, then 80% of the power is the first power gradient, 70% of the power is the second power gradient, 60% of the power is the third power gradient, and so on. When the power of the backup power supply 21 is between 80% and 70% during use, it is considered that the power gradient of the backup power supply 21 has dropped by one interval.

[0104] S204: Obtain the number of circuit breakers 1 controlled by the monitoring terminal 2. When the remaining power of the backup power source 21 decreases gradually, reduce the number of circuit breakers 1 monitored simultaneously.

[0105] During implementation, the number of circuit breakers 1 controlled by the monitoring terminal 2 is obtained. For example, a monitoring terminal 2 controls 9 circuit breakers 1, which are numbered 1 to 9. The line with the ground fault corresponds to circuit breaker 1 No. 9. Besides the circuit breaker 1 with the ground fault, the monitoring terminal 2 needs to monitor the remaining 8 circuit breakers 1, which are numbered 1 to 8.

[0106] Before the power gradient decreases, it is necessary to monitor circuit breakers 1 from 1 to 8 at the same time. If the power gradient decreases by one gradient at this time, circuit breakers 1 from 1 to 7 are monitored in the first time period, and in the next time period, circuit breakers 1 from 2 to 8 are monitored. In the next time period, circuit breakers 1 from 3 to 8 and 1 are monitored, and so on, and then circuit breakers 1 from 4 to 8 and 1 and 2 are monitored.

[0107] That is to say, after the power gradient decreases, the use time of the backup power supply 21 of the monitoring terminal 2 is extended by reducing the number of circuit breakers 1 monitored simultaneously, so that the monitoring terminal 2 can obtain a longer battery life with the support of the backup power supply 21.

[0108] Refer to the attached Figure 4 and attached Figure 5As shown, in step S204, reducing the number of circuit breakers 1 monitored simultaneously includes the following processing steps:

[0109] S301 : Virtualize multiple circuit breakers 1 controlled by the monitoring terminal 2 , except those that have experienced ground faults, to form a monitoring target 4 , where each unit in the monitoring target 4 corresponds to a different circuit breaker 1 .

[0110] In practice, multiple circuit breakers 1 are virtualized to form monitoring targets 4, and the attached Figure 6 , monitoring target 4 refers to the attached Figure 6 In the circular pattern, each small circular unit icon on this circular diagram represents a different circuit breaker 1, that is, the circuit breaker 1 controlled by the monitoring terminal 2 except the circuit breaker 1 that has a ground fault. The circumferential angle occupied by each unit is equal to the circumference of the large circle, that is, the small circular icons are evenly distributed on the circumference of the large circle.

[0111] For operator monitoring, Figure 6 The monitoring target 4 can be displayed on the display screen of the operating device to facilitate the operator or background recording and observation, or it can be simply used as a calculation process without being reflected.

[0112] S302 : Calculate the number of effective units based on the number of circuit breakers 1 controlled by the monitoring terminal 2 except those that have experienced ground faults and the number of circuit breakers 1 reduced due to the decrease in power gradient.

[0113] In practice, the number of circuit breakers 1 controlled by the monitoring terminal 2 and excluding those that have experienced ground faults is subtracted from the number of circuit breakers 1 reduced due to the decrease in power gradient to obtain the number of effective units, that is, the number of circuit breakers 1 that need to be monitored simultaneously.

[0114] S303 , forming a dynamic ring 5 with a gap 51 based on the number of multiple valid units.

[0115] In implementation, combined with Figure 6 and attached Figure 7 As shown, the dynamic ring 5 with a gap 51 is composed of multiple small circular unit icons, each of which represents an effective unit, that is, each small circular unit icon corresponds to a circuit breaker 1. The radius of the large circle where the centers of the multiple small circular unit icons are located is consistent with the radius of the large circle of the monitoring target 4.

[0116] The spacing between adjacent small circular unit icons on the dynamic ring 5 is equal to the spacing between adjacent units on the monitoring target 4. Since the monitoring target 4 and the dynamic ring 5 have the same outer radius and the same unit spacing, but the number of units is different, there will be a gap 51 on the dynamic ring 5, that is, a vacancy of an active unit, thus forming a gap 51.

[0117] S304 : Calculate the deflection angle based on the number of circuit breakers 1 controlled by the monitoring terminal 2 and other than those that have experienced ground faults.

[0118] In implementation, the calculation of the relevant deflection angle is described in detail later.

[0119] S305 , rotating the dynamic ring 5 on the monitoring target 4 at a deflection angle and a preset adjustment period. The units where the dynamic ring 5 and the monitoring target 4 overlap are monitoring units, and the units of the monitoring target 4 corresponding to the gaps 51 of the dynamic ring 5 are non-monitoring units.

[0120] During implementation, the dynamic ring 5 is rotated on the monitoring target 4. For the sake of vivid description and demonstration, it can be understood that the dynamic ring 5 and the monitoring target 4 overlap (the unit icons also overlap), the center of the large circle on the outer periphery of the monitoring target 4 is used as the rotation center, the calculated deflection angle is used as the central angle of each rotation of the dynamic ring 5, and the preset adjustment period is used as the intermittent period of the rotation of the dynamic ring 5, and the dynamic ring 5 is rotated on the monitoring target 4.

[0121] After each rotation, the unit of the monitoring target 4 corresponding to the notch 51 on the dynamic ring 5 is a non-monitored unit, that is, the unit corresponding to the circuit breaker 1 that does not need to be monitored simultaneously this time; the unit where the dynamic ring 5 and the monitoring target 4 overlap is a monitored unit, that is, the unit corresponding to the circuit breaker 1 that needs to be monitored simultaneously this time.

[0122] By rotating the dynamic ring 5 on the monitoring target 4 as described above, it is determined which circuit breakers 1 need to be monitored simultaneously and which circuit breakers 1 do not need to be monitored simultaneously each time the power gradient of the backup power supply 21 decreases, thereby reducing the number of circuit breakers 1 to be monitored simultaneously, thereby reducing the operating load of the monitoring terminal 2, reducing power consumption, and extending the operating time of the monitoring terminal 2.

[0123] The deflection angle is calculated using the following formula:

[0124] ,

[0125] is the deflection angle, The number of circuit breakers 1 controlled by the monitoring terminal 2 and not having ground faults. That is, it corresponds to the 360 degrees of the entire circle angle. The number of circuit breakers 1 controlled by the monitoring terminal 2 and other than those that have ground faults is corresponding. and The ratio of represents the center angle occupied by each unit of the monitoring target 4.

[0126] The number of effective units is calculated using the following formula:

[0127] ,

[0128] is the number of effective units, The number of circuit breakers 1 controlled by monitoring terminal 2 that have not experienced ground faults, The number of circuit breakers 1 reduced due to the decrease in power gradient, is the number of circuit breakers 1 reduced due to the decrease in the power gradient, and the difference between the two represents the number of effective units in the dynamic ring 5.

[0129] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application in turn. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A distributed ground fault line selection system based on an intelligent grounding device, characterized by: It includes a circuit breaker (1) for controlling the closing and opening of a corresponding line; A current transformer 1 for detecting the zero-sequence current value of the corresponding line; A preprocessor for collecting a zero-sequence current value signal of the current transformer 1 and transmitting an alarm signal to the intelligent grounding device (3) and the monitoring terminal (2); An intelligent grounding device (3) for receiving an alarm signal, transferring a ground fault current, and determining a phase where the ground fault is located; A monitoring terminal (2) for receiving an alarm signal and controlling the opening of a circuit breaker (1); The intelligent grounding device (3) includes a controller, a switch 1 (31), a phase-splitting switch (32) and a current-limiting resistor (33) connected in series, wherein the switches in the phase-splitting switch (32) correspond to three-phase circuits respectively, the switch 1 (31) is connected in parallel to the current-limiting resistor (33), and a current transformer 2 (331) is provided on the grounding circuit of the current-limiting resistor (33); The intelligent grounding device (3) further includes a three-phase switch (34) and a grounding transformer (35) connected in series, wherein the input end of the three-phase switch (34) is connected to the three-phase line, and the output end of the grounding transformer (35) is grounded; The controller is used to collect the three-phase line voltage value, the zero-sequence voltage value and the current value of the current limiting resistor (33), and control the closing and opening of the phase switch (32), the switch 1 (31) and the three-phase switch (34); After the monitoring terminal (2) controls the circuit breaker (1) of the faulty line to open, the following steps are included: Acquiring driving power information of the monitoring terminal (2); Based on the driving power information, identifying whether the driving power of the monitoring terminal (2) comes from a backup power supply (21) or a power grid; if the driving power comes from the backup power supply (21), acquiring the remaining power information of the monitoring terminal (2); Based on the remaining power information, dividing the remaining power into a plurality of power gradients according to preset power percentages; The number of circuit breakers (1) controlled by the monitoring terminal (2) is obtained, and when the remaining power of the backup power supply (21) decreases in a power gradient, the number of circuit breakers (1) monitored simultaneously is reduced; The reducing the number of circuit breakers (1) to be monitored simultaneously comprises: A plurality of circuit breakers (1) controlled by the monitoring terminal (2) other than those having ground faults are virtualized to form a monitoring target (4), wherein each unit in the monitoring target (4) corresponds to a different circuit breaker (1); Calculating the number of effective units based on the number of circuit breakers (1) controlled by the monitoring terminal (2) other than those that have experienced ground faults and the number of circuit breakers (1) reduced by the power gradient decrease; Based on the number of multiple effective units, a dynamic ring (5) with a gap (51) is formed; Calculating a deflection angle based on the number of circuit breakers (1) controlled by the monitoring terminal (2) other than those in which a ground fault has occurred; The dynamic ring (5) is rotated on the monitoring target (4) at a deflection angle and a preset adjustment period. The unit where the dynamic ring (5) and the monitoring target (4) overlap is the monitoring unit, and the unit of the monitoring target (4) corresponding to the notch (51) of the dynamic ring (5) is the non-monitoring unit.

2. The distributed ground fault line selection system based on an intelligent grounding device according to claim 1, characterized in that: The opening time of the circuit breaker (1) is consistent with the time when the fault line selection information of the intelligent grounding device (3) is sent.

3. The distributed ground fault line selection method based on an intelligent grounding device according to claim 1 is characterized in that: The deflection angle is calculated by the following formula: ， is the deflection angle, The number of circuit breakers (1) controlled by the monitoring terminal (2) except those having ground faults.

4. The distributed ground fault line selection method based on an intelligent grounding device according to claim 1 is characterized in that: The effective unit quantity is calculated by the following formula: ， is the number of effective units, The number of circuit breakers (1) controlled by the monitoring terminal (2) other than those having ground faults, The number of circuit breakers (1) is reduced due to the decrease in the power gradient.

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