A low voltage Internet of Things circuit breaker and fault detection method thereof

Abstract

The present invention relates to a low-voltage Internet of Things circuit breaker and a fault detection method thereof. A low-voltage Internet of Things circuit breaker comprises a current transformer, a voltage transformer, a sampling module, an NB‑IoT communicator, a temperature detection module, a switch drive module, a power supply module and a processor; the current transformer and the voltage transformer are respectively connected to the sampling module; the sampling module, the NB‑IoT communicator, the temperature monitoring module, the switch drive module and the power supply module are respectively connected to the processor. 1. The Internet of Things circuit breaker provided by the present invention integrates the functions of Internet of Things communication, protection, metering, fault analysis and reporting, while ensuring the miniaturization of the equipment, and the data acquisition has high accuracy and wide range; 2. The circuit breaker provided by the present invention adopts NB‑IoT Internet of Things communication technology, is stably connected to the main station, and greatly improves the speed of power grid data statistics and allocation, and has low energy consumption and wide coverage.

Description

Technical Field

[0001] The present invention relates to a low-voltage Internet of Things, and in particular to a low-voltage Internet of Things circuit breaker and a fault detection method thereof. Background Art

[0002] Circuit breakers are a key device widely used in low-voltage distribution network systems, and the requirements for them are getting higher and higher. The new generation of circuit breakers is developing in the direction of intelligence, miniaturization, reliability, and multi-functions. At present, the intelligent circuit breaker products on the market are uneven.

[0003] Traditional circuit breakers only have basic thermal-magnetic tripping protection functions. Some electronic circuit breakers developed in recent years have both shunt tripping protection and RS485 communication functions, but there are still some shortcomings: some intelligent circuit breakers are large in size, which violates the development trend of miniaturized design, reliable reporting of fault information has not yet been achieved, the sampling accuracy is low and cannot meet the needs of high-precision metering and intelligent substation management, the power supply reliability and equipment intelligence level need to be improved, and the current application scope is severely restricted and cannot meet the development requirements of the smart power Internet of Things.

[0004] The reliability of fault reporting needs to be improved. At present, the power distribution data of low-voltage substations are uploaded to the main station via TTU (distribution terminal). When a fault occurs, the monitoring equipment at all levels of the faulty line will rush to report the event. Due to the large number of equipment, the channel is very easy to be congested, it is easy to be affected by electromagnetic interference during the transmission process, the signal coverage area is limited, and the power outage operation time is not long. The success rate of fault reporting (especially power outage faults) is low, resulting in the main station being unable to perceive the abnormal conditions of each topological level of the terminal power grid in real time, which brings great pressure to the daily operation and maintenance of the power company.

[0005] The current transformer in the electronic circuit breaker not only serves as a current self-generated power supply, but also plays the role of current sampling. The currently known single-core current transformer solution is difficult to take into account both efficient power supply and wide-range, high-precision sampling. It only starts to draw power when the current is relatively large; the current measurement accuracy is poor, and the sampling resistor is connected in series between the rectifier diode and the load, which causes crossover distortion in the current waveform. The sampling load changes have a great impact on it, and it cannot meet the new requirements of the circuit breaker (such as wide-range fault current monitoring, metering, fault arc, line loss analysis, etc.). The dual-core current transformer solution will increase the size and cost of the low-voltage circuit breaker, making it difficult to apply in low-voltage circuit breakers with miniaturization requirements. In addition, due to its own characteristics, the Rogowski coil sampling solution is easily interfered, and the induction is not sensitive and the accuracy is poor under low current conditions. There is a situation where a fault occurs but is not detected, which especially affects the reliability of the trip protection and poses a serious safety hazard.

[0006] In addition, in order to take into account the sampling range of the single-core coil, the current transformer cannot obtain enough energy from the circuit when the current is small. As a result, the circuit breaker controller cannot work properly and may malfunction. If a switching power supply or an external auxiliary power supply is used, a power module must be added, which will inevitably increase the size of the device and make it difficult to use in situations where the volume is limited. Among them, the switching power supply will generate high-frequency interference signals. The external power module needs to be connected to the circuit breaker controller by wires, which is easy to introduce new interference and have an adverse effect on the operation of the equipment.

[0007] When the switch is powered on for a long time, the contact status between its main circuit terminals and the switch contacts will gradually deteriorate. Currently, there is no suitable solution to achieve early warning and protection.

[0008] The patent document with the patent number ZL201910585428.X discloses a metering intelligent circuit breaker based on the Internet of Things, including a CPU module, a signal acquisition module, a metering module, a power module, a mechanical control module, a communication module and an input / output module, wherein the metering module includes a metering chip, the power module includes a self-generated power supply circuit unit, the communication module includes a wired 485 communication unit and a wireless Internet of Things communication module, the mechanical control module includes a control signal output unit and an equipment signal feedback input unit, and the input / output module includes a key unit and a display unit; the voltage signal in the line is converted by the power module into a signal that can be collected by the metering chip and sent to the metering module, which not only realizes the requirements of high-precision metering, rapid protection action, and reliable fault detection, but also can directly realize the direct connection between data and remote terminals through the Internet of Things technology, greatly improving the spatial distance of remote control, and also improving the speed of grid data statistics and deployment. However, the above problems still exist.

[0009] Therefore, the existing circuit breakers have deficiencies and need to be improved and enhanced. Summary of the invention

[0010] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a low-voltage Internet of Things circuit breaker and a fault detection method thereof, which can meet the future market development and industry standard of an electric power Internet of Things intelligent circuit breaker.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A low-voltage Internet of Things circuit breaker comprises a current transformer, a voltage transformer, a sampling module, an NB-IoT communicator, a temperature detection module, a switch drive module, a power supply module and a processor; the current transformer and the voltage transformer are respectively connected to the sampling module; the sampling module, the NB-IoT communicator, the temperature monitoring module, the switch drive module and the power supply module are respectively connected to the processor.

[0013] Preferably, in the low-voltage Internet of Things circuit breaker, the current transformer has a single magnetic core coil and three taps, and the three taps divide the single magnetic core coil into two parts; one part is a coil with few turns, and the other part is a coil with many turns.

[0014] Preferably, the sampling range of the current transformer of the low-voltage Internet of Things circuit breaker is: 0-10I E ; Among them, I E is the rated current.

[0015] Preferably, in the low-voltage IoT circuit breaker, the power module is a CT power supply device and a backup capacitor;

[0016] The CT power supply device comprises a rectifier bridge, a voltage regulator tube, and a voltage regulator connected in sequence; the rectifier bridge is connected to two taps of the few-turn coil; the voltage regulator is connected to the processor;

[0017] The backup capacitor is charged through the CT power supply device after the circuit breaker is started, and is used to supply power to the processor when the CT power supply device cannot supply power.

[0018] Preferably, in the low-voltage IoT circuit breaker, the sampling module comprises a sampling resistor unit, a characteristic signal sampling channel and a metering channel; the sampling resistor unit is connected to the characteristic signal sampling channel and the metering channel respectively;

[0019] The multi-turn coils of the voltage transformer and the current transformer are respectively connected to the sampling resistor unit; the characteristic signal sampling channel and the metering channel are respectively connected to the processor.

[0020] Preferably, in the low-voltage Internet of Things circuit breaker, the metering channel has a metering chip, and the model of the metering chip is ATT7022E.

[0021] Preferably, the low-voltage Internet of Things circuit breaker, the NB-IoT communicator is a BC95 communication module.

[0022] A circuit breaker fault detection method for the low-voltage Internet of Things circuit breaker, comprising the steps of:

[0023] S1, the current transformer, the voltage transformer and the temperature detection module detect the line current, the line voltage and the contact temperature respectively, and send the detection data to the processor respectively;

[0024] S2. The processor determines whether there is a fault in the circuit breaker and its nearby circuits based on the line current, the line voltage and the contact temperature. If so, the fault information is transmitted to the server through the NB-IoT communicator, and a shunt tripping operation is performed; if not, no operation is performed.

[0025] Preferably, in the circuit breaker fault detection method, the step S2 includes detecting the fault arc, which specifically includes:

[0026] S211, the processor determines whether there is a high-frequency characteristic signal according to the line current and the line voltage, and if so, starts the wave recording operation and executes step S212; if not, no operation is performed;

[0027] S212, determining whether the circuit breaker has performed an opening and closing operation or a switch position remote signal change at the current moment, if so, executing step S213; if not, executing step S211;

[0028] S213, judging whether the high-frequency characteristic signal is an arc fault signal according to the recorded data, if so, executing step S214; if not, executing step S211;

[0029] S214, determining whether the contact temperature is greater than a temperature threshold, if so, determining that an arc fault exists; if not, reporting the abnormal situation to a master station.

[0030] Preferably, in the circuit breaker fault detection method, in step S2, the step of using the NB-IoT communicator to communicate is:

[0031] S221, initializing the NB-IoT communicator;

[0032] S222, detecting whether the signal strength of the NB-IoT communicator is greater than the first signal value, if yes, executing step S224; if no, executing step 223;

[0033] S223, determining whether the number of times that the signal strength is not greater than the first signal value is greater than a first threshold, if so, executing step S228; if not, executing step S222;

[0034] S224, configure the network access information of the NB-IoT communicator, and determine whether the network access is successful. If so, execute step S226; if not, execute step S225;

[0035] S225, determining whether the number of network access failures is greater than a second threshold, if so, executing step S228; if not, executing step S224;

[0036] S226, send data and determine whether the data is sent successfully, if yes, then end; if not, execute step S227;

[0037] S227, determining whether the number of unsuccessful data transmissions is greater than a third threshold, if so, executing step S228; if not, executing step S226;

[0038] S228. Transmit the communication error identification data to the processor, and execute step S221 after a predetermined time interval.

[0039] Compared with the prior art, the present invention provides a low-voltage Internet of Things circuit breaker and a fault detection method thereof, which has the following beneficial effects:

[0040] 1. The IoT circuit breaker provided by the present invention integrates IoT communication, protection, metering, fault analysis and reporting functions, while ensuring the miniaturization of the equipment and high data acquisition accuracy and wide range;

[0041] 2. The circuit breaker provided by the present invention adopts NB-IoT Internet of Things communication technology, is stably connected to the main station, and greatly improves the speed of power grid data statistics and allocation. It has the characteristics of low energy consumption, wide coverage, and high cost performance. It can solve the problem of unsmooth communication in the "last mile" of the power grid, and enables each topological level circuit breaker to have the function of actively reporting power outage faults and greatly improve the success rate of power outage fault reporting;

[0042] 3. The circuit breaker provided by the present invention uses a single-core three-tap current transformer, which solves the problem that a single-core current transformer is difficult to achieve both reliable power supply and high-precision sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural block diagram of a low voltage circuit breaker provided by the present invention;

[0044] Figure 2 It is a structural block diagram of a current transformer, a voltage transformer, a sampling module and a processor in a low-voltage circuit breaker provided by the present invention;

[0045] Figure 3 It is a flow chart of a low voltage circuit breaker fault detection method provided by the present invention;

[0046] Figure 4 It is a flow chart of a method for determining whether a circuit breaker has a fault arc provided by the present invention;

[0047] Figure 5 It is a flow chart of the circuit breaker communication method provided by the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] The present invention provides a low-voltage Internet of Things circuit breaker, including a current transformer 1, a voltage transformer 2, a sampling module 3, an NB-IoT communicator 4, a temperature detection module 5, a switch drive module 7, a power module 8 and a processor 6; the current transformer 1 and the voltage transformer 2 are respectively connected to the sampling module 3; the sampling module 3, the NB-IoT communicator 4, the temperature monitoring module, the switch drive module 7, and the power module 8 are respectively connected to the processor 6. The temperature detection module 5 is a temperature sensor, which is fitted on the main circuit wiring terminal and the opening and closing contact (contact switch) of the circuit breaker, and is used to detect the temperature of the installation position. The preferred detection range of the use temperature is -50℃-200℃, and meets the insulation withstand voltage strength of 2.5KV; the switch drive module 7 is used to drive the opening and closing contacts of the circuit breaker to perform switching actions; the processor 6 is preferably an MCU commonly used in the art, and the specific model is not limited, as long as it can realize the prejudgment of the preset scheme for the internal fault of the circuit breaker.

[0050] Accordingly, the present invention also provides a circuit breaker fault detection method for the low-voltage Internet of Things circuit breaker, comprising the steps of:

[0051] S1, the current transformer 1, the voltage transformer 2 and the temperature detection module 5 detect the line current, line voltage and contact temperature respectively, and send the detection data to the processor 6 respectively; it should be noted that after the circuit breaker is started, the current transformer 1 takes power to supply power to the circuit breaker system and charges the backup capacitor at the same time;

[0052] S2, the processor 6 determines whether there is a fault arc in the circuit breaker according to the line current, the line voltage and the contact temperature. If so, the fault information is transmitted to the server through the NB-IoT communicator 4, and the shunt tripping operation is performed; if not, no operation is performed. Here, it should be noted that the processor 6 makes a comprehensive judgment based on the line current, the line voltage and the contact temperature, and not only identifies whether there is a fault arc, but also uses the judgment method commonly used in the field to determine other circuit breaker faults, such as abnormal current, leakage and other faults in the subordinate lines, and the component resistance of the circuit breaker itself is too high. The processor determines whether there is a fault according to the line current and the line voltage. The line fault includes overload, short circuit, overvoltage, undervoltage, and phase loss, and records the voltage and current data at the time of the fault. If yes, the fault and data are reported to the main station. If not, it is not executed. Among them, the fault protection setting parameters (current or voltage threshold and fault duration, etc.) can be set according to the specific situation on the spot, and the present invention does not limit it.

[0053] As a preferred solution, in this embodiment, the step S2 includes detecting the fault arc, which specifically includes:

[0054] S211, the processor 6 determines whether there is a high-frequency characteristic signal according to the line current and the line voltage, and if so, starts the wave recording operation and executes step S212; if not, no operation is performed;

[0055] S212, determining whether the circuit breaker has performed an opening and closing operation or a switch position remote signal change at the current moment, if so, executing step S213; if not, executing step S211;

[0056] S213, judging whether the high-frequency characteristic signal is an arc fault signal according to the recorded data, if so, executing step S214; if not, executing step S211;

[0057] S214, determining whether the contact temperature is greater than a temperature threshold, if so, determining that an arc fault exists; if not, reporting the abnormal situation to a master station.

[0058] Specifically, when the contact switch of the circuit breaker is in a state of long-term energized operation, the contact state of the main circuit terminal contacts and the opening and closing contacts will gradually deteriorate. The poor contact makes the voltage between the contacts sufficient to break through the air gap to generate a fault arc. A large amount of electron flow appears between the two contacts, generating high temperature and emitting strong light, which is very likely to cause a fire. When a fault arc occurs, the protection devices such as leakage, overcurrent and circuit breaker on the line may not be able to detect or quickly make a protective action to cut off the power supply. In general, after a fault arc occurs, there will be an arc first and then a high temperature. Therefore, in order to enable the circuit breaker protection to be advanced, to discover hidden dangers as early as possible, and to carry out unplanned power outages or power outages, it is not possible to rely solely on the contact temperature of the contact to make judgments. In addition, the arcs generated by circuit breakers under normal circumstances can be divided into two types, one is a normal operating arc, called a "good arc"; the other is a fault arc, called a "bad arc"; these two arcs need to be identified to prevent misjudgment. The circuit breaker fault detection method provided by the present invention is based on local edge computing to realize the analysis of fault arcs, and adopts factors such as characteristic current, temperature of wiring and contacts, changes in voltage recording data, and whether the contact switch is remotely signaled to change position to identify, protect and warn of fault arcs.

[0059] As a preferred solution, in this embodiment, the NB-IoT communicator 4 is a BC95 communication module.

[0060] Accordingly, as a preferred solution, in this embodiment, in step S2, the steps of communicating using the NB-IoT communicator 4 are:

[0061] S221, initializing the NB-IoT communicator 4;

[0062] S222, detecting whether the signal strength of the NB-IoT communicator 4 is greater than the first signal value, if yes, executing step S224; if no, executing step 223;

[0063] S223, determining whether the number of times that the signal strength is not greater than the first signal value is greater than a first threshold, if so, executing step S228; if not, executing step S222;

[0064] S224, configure the network access information of the NB-IoT communicator 4, and determine whether the network access is successful. If so, execute step S226; if not, execute step S225;

[0065] S225, determining whether the number of network access failures is greater than a second threshold, if so, executing step S228; if not, executing step S224;

[0066] S226, send data and determine whether the data is sent successfully, if yes, then end; if not, execute step S227;

[0067] S227, determining whether the number of unsuccessful data transmissions is greater than a third threshold, if so, executing step S228; if not, executing step S226;

[0068] S228, transmitting the communication error identification data to the processor 6, and executing step S221 after a predetermined time interval.

[0069] Specifically, it should be noted that the value range of the first threshold, the second threshold, and the third threshold are all 3-8 times, and the specific applicable values ​​are not limited. The preferred set value is 5; at the same time, the preferred range of the first signal value is [-100, -50] dBm, and further preferred is -85 dBm.

[0070] The power Internet of Things communication method of the circuit breaker provided by the present invention adopts NB-IoT (Narrow Band Internet of Things) wireless communication technology, and its communication system includes the NB-IoT communicator 4, a base station, an IOT core network, and a monitoring main station. In a specific application, the NB-IoT communicator 4 is used to send communication data to the base station, and the communication data is sent to the IOT core network through the base station, and then to the monitoring main station. The monitoring main station can be a back-end distribution substation main station or a monitoring server with a function of monitoring the power consumption of the distribution substation. Of course, in specific use, in order to facilitate operation and maintenance, the monitoring main station can also send communication data to a mobile terminal for information alarm or other troubleshooting instructions. The demand for wide coverage, low power consumption and low cost in the low-voltage field is very clear. Therefore, the circuit breaker based on NB-IOT Internet of Things has the advantages of stable and reliable fault reporting, deep communication coverage, miniaturization, low power consumption and low cost. Compared with the data recovery success rate of wired PLC (Power Line Communication) communication of about 60%, NB-IoT communication can ensure a data recovery success rate of 99%, and the reliability is greatly improved. At the same time, compared with Wi-Fi, Bluetooth, and Zigbee, which are only for short-distance interconnection applications, the widely commercialized 2G / 3G / 4G has high power consumption, weak signals in basements or deep locations, etc., NB-IoT communication has long-distance and wide-area communication technology, as well as high coverage capability, which is more advantageous and makes up for the technical deficiencies. It can cover even in underground garages, basements, underground pipelines and other places where signals are difficult to reach. When a fault occurs, protection and reporting are performed according to the protection setting values ​​of different fault types. Especially when a current fault occurs, the circuit breaker needs to be protected quickly. It can start quickly and complete fault analysis and tripping within 100ms, and actively report the fault to the main station. Through the above communication transmission operation, the data transmission efficiency can be greatly improved, and the communication data can be quickly transmitted to the monitoring main station or the background server.

[0071] As a preferred solution, in this embodiment, the current transformer 1 has a single magnetic core coil and three taps, and the three taps divide the single magnetic core coil into two parts; one part is a coil with few turns, and the other part is a coil with many turns.

[0072] As a preferred solution, in this embodiment, the sampling range of the current transformer 1 is: 0-10I E ; Among them, I E is the rated current.

[0073] As a preferred solution, in this embodiment, the power module 8 is a CT power taking device (not shown) and a backup capacitor (not shown);

[0074] The CT power supply device includes a rectifier bridge 81, a voltage regulator tube 82, and a voltage regulator 83 connected in sequence. Figure 2 The rectifier bridge 81 is connected to the two taps of the few-turn coil; the voltage regulator is connected to the processor 6; the rectifier bridge 81, the voltage regulator tube 82, and the voltage regulator 83 are all commonly used rectifier and voltage regulator devices in the art, and will not be described in detail;

[0075] The backup capacitor is charged by the CT power supply device after the circuit breaker is started, and is used to supply power to the processor 6 when the CT power supply device cannot supply power. The backup capacitor is a small-capacity capacitor, and the specific capacity is set according to the on-site requirements and is not limited.

[0076] Specifically, the current transformer 1 used in the circuit breaker provided by the present invention is a single-core three-tap current transformer 1, that is, it has a core coil, but is divided into two parts using three taps, which are used for different functions. Among them, there is a multi-turn coil between taps 2 and 3, and the preferred number of turns is 5000-10000 turns, and more preferably 6000 turns, which is only used for sampling, so that the fault protection setting value can be set in a wide range; there is a few-turn coil between taps 1 and 2, and the preferred number of turns is 300-1000 turns, and more preferably 500 turns, which is only used for efficient power extraction, so that it can be powered and operated normally even under a relatively small current. Although power extraction and sampling share a transformer, two different coil loops are formed between taps 1 and 2 and between taps 2 and 3, which can simultaneously achieve efficient power extraction and wide-range high-precision sampling. Among them, the power extraction coil loop calculates and designs the optimal number of turns based on impedance matching, maximum output power, and efficiency principles. The sampling coil loop is designed according to the principles of high precision, anti-interference and anti-saturation, with a circular magnetic core, symmetrical winding, and the primary side threaded from the center point of the magnetic core.

[0077] Among them, the 500-turn coil between taps 1 and 2 is designed to be used only for efficient power extraction, so that it can be powered and operate normally even at a relatively low current. When the power is just turned on, the system is powered first, so that the system can start as soon as possible to conduct fault analysis, and then the backup capacitor is turned on to charge and store energy. If the collected data is greater than the protection setting value, the fault trip protection operation is performed by controlling the shunt trip drive (switch drive module 7), and the small backup capacitor continues to power the system and its Internet of Things communication module, and actively reports the fault and switch telesignal status to the main station, prompting immediate maintenance.

[0078] The development of intelligent circuit breakers is not limited to basic protection (circuit breaking, grounding) and metering, but also needs to realize extended functions, such as arc monitoring, human electric shock monitoring, auxiliary topology identification, etc. Of course, the realization of these functions requires the identification of characteristic signals. Therefore, in order to realize the above functions on the basis of ensuring the miniaturization of the circuit breaker, the single-core three-tap current transformer 1 is used. The 6000-turn multi-turn coil between taps 2 and 3 is designed only for sampling, and a small-resistance sampling resistor with fixed impedance is connected in series to realize high-precision metering and characteristic signal sampling. Its metering sampling value can reach 1.5 times the rated current, and its characteristic signal sampling measurement value can reach more than 10 times the rated current, realizing a wide range of fault protection setting values.

[0079] As a preferred solution, in this embodiment, the sampling module 3 includes a sampling resistor unit 31, a characteristic signal sampling channel 32 and a metering channel 33; the sampling resistor unit 31 is connected to the characteristic signal sampling channel 32 and the metering channel 33 respectively;

[0080] The multi-turn coils of the voltage transformer 2 and the current transformer 1 are respectively connected to the sampling resistor unit 31; the characteristic signal sampling channel 32 and the metering channel 33 are respectively connected to the processor 6. Specifically, the sampling resistor includes a current sampling resistor and a voltage sampling resistor; the current sampling resistor is connected to the current transformer 1, and is respectively connected to the characteristic signal sampling channel 32 and the metering channel 33; the voltage sampling resistor is connected to the voltage transformer 2, and is respectively connected to the characteristic signal sampling channel 32 and the metering channel 33; and it is realized that both the characteristic signal sampling channel 32 and the metering channel 33 can receive the current detection data and the voltage detection data transmitted by the current transformer 1 and the voltage transformer 2.

[0081] The characteristic signal sampling channel 32 includes a characteristic signal conditioning unit and a high-speed sampling unit. The characteristic signal conditioning unit is used to filter and amplify the received signal using technical means commonly used in the field without limitation. The high-speed sampling channel preferably uses an ADC (analog to digital converter) detection channel on the MCU chip of the processor 6.

[0082] The metering channel 33 includes a metering signal conditioning unit and a metering chip. The metering signal conditioning unit has similar functions to the characteristic signal conditioning unit and is not limited thereto. The metering signal conditioning unit is used to condition the detection data sent by the voltage transformer 2 and the current transformer 1 and send the conditioning data to the metering chip. The metering chip performs conventional data metering of the circuit breaker. As a preferred solution, in this embodiment, the model of the metering chip is ATT7022E.

[0083] Specifically, the measurement focus and measurement range of metering and characteristic signal sampling are significantly different, so metering and characteristic signal sampling are designed as two dedicated and different channels, and the meter is calibrated separately to achieve high-precision characteristic signal sampling and metering. The same current transformer 1 and sampling resistor will be shared, and the characteristic current high-speed acquisition will be completed through the conditioning circuit (characteristic signal conditioning unit) and A / D conversion (ADC channel of processor 6) of the fault sampling channel; and the metering data will be calculated through the conditioning circuit (metering signal conditioning unit) and metering chip of the metering channel 33.

[0084] Metering channel 33 uses ATT7022E multifunctional, high-performance three-phase electric energy dedicated metering chip. It can measure active power, reactive power, apparent power, active energy and reactive energy of each phase and combined phase, and can also measure parameters such as current, voltage effective value, power factor, phase angle, frequency, etc. of each phase.

[0085] The characteristic signal sampling channel 32 is used to realize characteristic signal sampling, recording, and extraction. Among them, the high-speed acquisition of 4K frequency not only meets the basic fault protection needs, but also meets the extended application needs such as arc monitoring, human electric shock monitoring, and auxiliary topology identification. Among them, it has a characteristic signal automatic trigger recording mechanism to record the waveform at the time of the fault for further data analysis.

[0086] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. A low voltage Internet of Things circuit breaker, characterized in that: It includes a current transformer, a voltage transformer, a sampling module, an NB-IoT communicator, a temperature detection module, a switch drive module, a power supply module and a processor; the current transformer and the voltage transformer are respectively connected to the sampling module; the sampling module, the NB-IoT communicator, the temperature monitoring module, the switch drive module and the power supply module are respectively connected to the processor; the current transformer has a single magnetic core coil and three taps, and the three taps divide the single magnetic core coil into two parts, one of which is a few-turn coil and the other is a multi-turn coil; the sampling range of the current transformer is: 0-10IE, where IE is the rated current; the power supply module is a CT power supply device and A backup capacitor, the CT power supply device includes a rectifier bridge, a voltage regulator, and a voltage regulator connected in sequence, the rectifier bridge is connected to the two taps of the few-turn coil; the voltage regulator is connected to the processor; the backup capacitor is charged by the CT power supply device after the circuit breaker is started, and is used to supply power to the processor when the CT power supply device cannot supply power; the sampling module includes a sampling resistor unit, a characteristic signal sampling channel and a metering channel; the sampling resistor unit is respectively connected to the characteristic signal sampling channel and the metering channel; the multi-turn coils of the voltage transformer and the current transformer are respectively connected to the sampling resistor unit; the characteristic signal sampling channel and the metering channel are respectively connected to the processor.

2. The low-voltage Internet of Things circuit breaker according to claim 1, characterized in that: The metering channel has a metering chip, and the model of the metering chip is ATT7022E.

3. The low voltage Internet of Things circuit breaker according to claim 1, characterized in that: The NB-IoT communicator is a BC95 communication module.

4. A circuit breaker fault detection method for the low-voltage Internet of Things circuit breaker according to any one of claims 1 to 3, characterized in that: Includes steps: S1, the current transformer, the voltage transformer and the temperature detection module detect the line current, the line voltage and the contact temperature respectively, and send the detection data to the processor respectively; S2. The processor determines whether there is a fault in the circuit breaker and its nearby circuits based on the line current, the line voltage and the contact temperature. If so, the fault information is transmitted to the server through the NB-IoT communicator, and a shunt tripping operation is performed; if not, no operation is performed.

5. The circuit breaker fault detection method according to claim 4, characterized in that: The step S2 includes detecting the fault arc, which specifically includes: S211, the processor determines whether there is a high-frequency characteristic signal according to the line current and the line voltage, and if so, starts the wave recording operation and executes step S212; if not, no operation is performed; S212, determining whether the circuit breaker has performed an opening and closing operation or a switch position remote signal change at the current moment, if so, executing step S213; if not, executing step S211; S213, judging whether the high-frequency characteristic signal is an arc fault signal according to the recorded data, if so, executing step S214; if not, executing step S211; S214, determining whether the contact temperature is greater than a temperature threshold, if so, determining that an arc fault exists; if not, reporting the abnormal situation to a master station.

6. The circuit breaker fault detection method according to claim 4, characterized in that: In step S2, the steps of communicating using the NB-IoT communicator are: S221, initializing the NB-IoT communicator; S222, detecting whether the signal strength of the NB-IoT communicator is greater than the first signal value, if yes, executing step S224; if no, executing step 223; S223, determining whether the number of times that the signal strength is not greater than the first signal value is greater than a first threshold, if so, executing step S228; if not, executing step S222; S224, configure the network access information of the NB-IoT communicator, and determine whether the network access is successful. If so, execute step S226; if not, execute step S225; S225, determining whether the number of network access failures is greater than a second threshold, if so, executing step S228; If not, execute step S224; S226, send data and determine whether the data is sent successfully, if yes, then end; if not, execute step S227; S227, determining whether the number of unsuccessful data transmissions is greater than a third threshold, if so, executing step S228; If not, execute step S226; S228. Transmit the communication error identification data to the processor, and execute step S221 after a predetermined time interval.

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