Low-voltage distribution intelligent safety data monitoring terminal

Abstract

The invention discloses a low-voltage power distribution intelligent safety data monitoring terminal, which relates to the technical field of power distribution system monitoring and comprises a control module, a signal module, a branch loop data terminal module, a zero sequence mutual inductor, a current mutual inductor, a relay and the like. The control module injects a low-frequency alternating-current synchronous signal into an IT system, and the branch loop data terminal module decomposes a zero-sequence current collected by a zero-sequence mutual inductor into a 0-degree active current component and a 90-degree reactive current component by taking the synchronous signal as a reference, and uploads the components to the signal module; and the control module calculates the insulation resistance and the ground capacitance of each branch loop through a formula based on the injection signal voltage, the active current and the reactive current. The terminal can collect parameters such as three-phase voltage, current, voltage to ground, insulation resistance of main and branch loops, capacitance to ground and the like of a distribution network in real time, support visual operation, real-time data display and parameter setting through a touch screen, can trigger sound-light alarm for a fault branch loop, and can realize automatic or manual remote control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution system monitoring, and particularly relates to a low-voltage power distribution intelligent safety data monitoring terminal. BACKGROUND

[0002] In a low-voltage power distribution IT grounding system, insulation state monitoring is a core link to ensure safe and stable operation of the system, which needs to monitor key parameters such as insulation resistance and ground capacitance of the main branch circuit in real time to early warn of electric leakage faults and avoid electric shock or equipment damage accidents. Traditionally, such monitoring relies on IT distribution network secondary equipment, but with the increasing requirements for reliability and real-time performance of power distribution systems in the fields of industrial automation and intelligent manufacturing, the existing technology gradually exposes many defects and cannot meet the actual application requirements.

[0003] Firstly, the measurement accuracy of the existing IMD is limited in complex IT systems. There is generally a ground distributed capacitance in the IT grounding system, and the charging and discharging process of the capacitance will generate a capacitance current, which is superimposed with the electric leakage current, resulting in that the traditional equipment cannot accurately distinguish the influence of the electric leakage resistance and the ground capacitance, the insulation resistance measurement error is large, and false alarm or missed alarm easily occurs, especially in multi-loop and large-capacity industrial distribution networks, the problem is more prominent.

[0004] Secondly, the fault positioning and control capability is insufficient. The traditional equipment can only monitor the overall insulation state of the main loop and cannot independently monitor and collect parameters of each branch circuit. When an electric leakage fault occurs in the system, manual line-by-line troubleshooting is required, which is not only time-consuming and laborious, but also may cause production interruption due to long-time power outage. At the same time, the control execution mechanism responds slowly and cannot realize remote automatic control, and the timeliness and accuracy of safety protection are insufficient.

[0005] Thirdly, the real-time performance and system compatibility have shortcomings. The existing equipment relies on external master stations for data processing and instruction issuing, and the local edge side processing capability is weak, resulting in data response delay and inability to meet the real-time requirements of power distribution control. In addition, the communication interface is single and the protocol compatibility is poor, which makes it difficult to interface with modern platforms such as operation and maintenance management, industrial control, and artificial intelligence, and cannot provide detailed distribution network safety data for the upper system, restricting the intelligent management of the power distribution system.

[0006] Finally, the scalability and scene adaptability are limited. The number of loops of the traditional IMD is fixed, and the modular design is insufficient. When the scale of the distribution network expands, the entire equipment needs to be replaced or the system needs to be reconstructed, which is high in extension cost and long in cycle. In addition, the signal parameters are fixed and cannot be dynamically adjusted according to the ground capacitance and other working conditions, and the adaptability is poor in distribution networks of different scales and different load characteristics.

[0007] Therefore, in view of the defects of the existing IT distribution network insulation monitoring equipment in terms of measurement accuracy, fault positioning, real-time performance, expandability and the like, there is an urgent need for a low-voltage power distribution intelligent safety data monitoring terminal with innovative signal processing technology, independent monitoring capability of branch circuits, edge-side intelligent integration and modular expansion characteristics, so as to meet the safe operation and intelligent management requirements of modern low-voltage power distribution systems. SUMMARY

[0008] One object of the present application is to provide a low-voltage power distribution intelligent safety data monitoring terminal, which can realize real-time and accurate monitoring of safety data such as insulation resistance and capacitance to ground of the main branch circuit of the IT low-voltage power distribution system, eliminate distributed capacitance interference through injection of low-frequency synchronization signals and zero-sequence current orthogonal decomposition technology, support automatic or manual remote control of fault branch circuits, and have functions such as data acquisition, operation monitoring, intelligent alarm and information transmission, so as to replace traditional IT distribution network secondary equipment, meet the real-time performance, reliability and safety requirements of power distribution circuit operation, and provide detailed monitoring data for operation and maintenance, energy efficiency management and industrial control platforms, and adapt to the intelligent monitoring requirements of low-voltage power distribution scenarios of different scales.

[0009] According to the low-voltage power distribution intelligent safety data monitoring terminal of the embodiment of the present application, the control module, the signal module, at least one branch circuit data terminal module, the zero-sequence transformer, the current transformer and the relay actuator are included. The control module is in communication connection with the signal module and the touch screen respectively, and the signal module is connected with each branch circuit data terminal module through the 485 bus. The output end of the zero-sequence transformer and the current transformer is connected with the input end of the branch circuit data terminal module, and the output end of the branch circuit data terminal module is connected with the relay actuator. The control module is used for sending synchronization signals, operation monitoring and control instructions, the signal module is used for processing sensor data and executing control commands, and the branch circuit data terminal module is used for acquiring current signals and converting them into digital quantities.

[0010] Each module works cooperatively through a hierarchical communication architecture, and the control module serves as a core hub, which on the one hand realizes time sequence unification of the whole system through synchronization signals, and on the other hand manages the branch circuit data terminal modules through the signal module, the 485 bus adopts differential signal transmission, and is matched with terminal resistance design, so as to effectively reduce the influence of electromagnetic interference in the industrial environment on data transmission and ensure the stability of concurrent uploading of multiple circuit data.

[0011] Further, the control module adopts a high-performance 32-bit microcontroller MCU, the clock frequency of which is 48MHz, and the MCU is integrated with ADC, PWM, SCI, SPI and CAN peripherals, and is built-in with a real-time operating system, supporting multi-task processing, interruption management and task scheduling.

[0012] The real-time operating system of the MCU can prioritize tasks, for example, setting the fault alarm response as the highest priority, ensuring that the leakage fault can trigger the processing mechanism within 100ms, the integrated 12-bit ADC peripheral supports 16-channel analog simultaneous sampling, and cooperates with the PWM module to accurately control the output amplitude and frequency of low-frequency signals, providing high-precision original parameters for subsequent data calculation.

[0013] Further, the branch circuit data terminal module can decompose the zero sequence current signal collected by the zero sequence transformer into a 0° active current component and a 90° reactive current component, wherein the 0° active current component is the active current caused by the ground leakage resistance, and the 90° reactive current component is the reactive current caused by the ground distributed capacitance, and the active current and the reactive current with address information are uploaded to the signal module through the 485 bus.

[0014] The decomposition process adopts a quadrature demodulation algorithm based on a synchronization signal, accurately separates the two current components by comparing the phase with the low-frequency signal injected by the control module, and avoids the interference of the capacitance current on the leakage resistance judgment in traditional measurement; the address information adopts 8-bit binary coding, supports a maximum of 256 independent identifications of branch circuits, and the uploaded data frame contains a check bit to ensure that the signal module can identify and discard error data.

[0015] Further, it further includes a data calculation unit, which is arranged in the control module and is used for calculating the branch circuit insulation resistance and the ground capacitance based on the active current and the reactive current uploaded by the branch circuit data terminal module; the calculation formula of the insulation resistance is: Wherein R is the insulation resistance, U is the low-frequency alternating signal voltage between the control module injected line and the ground, and Ir is the 0° active current; The calculation formula of the ground capacitance is: Wherein C is the ground capacitance, Ic is the 90° reactive current, and f is the injection signal frequency.

[0016] The data calculation unit adopts a hardware acceleration operation module, which can complete the parameter calculation of a single branch circuit within 5ms and supports multi-circuit parallel processing; temperature compensation coefficients are automatically introduced during calculation to correct the transformer accuracy deviation caused by environmental temperature changes, wherein U is obtained in real time by the voltage sampling circuit inside the control module, and the sampling frequency is 1kHz, ensuring the timeliness of the parameters in the formula.

[0017] Further, the signal module comprises an isolation transformer, a signal processing unit and a communication interface, the signal processing unit can filter, amplify and analog-digital convert the current signal sent by the branch circuit data terminal module, and can read and write the address of the branch circuit data terminal module, and receive the operation command of the control module to control the circuit breaker in real time.

[0018] The isolation transformer adopts magnetic core isolation design, and the insulation strength reaches 5000VAC / 1min, effectively blocking the impact of high voltage of the power grid on the rear-end circuit. The filter circuit of the signal processing unit is a three-order Butterworth low-pass filter, with a cutoff frequency of 1kHz, which can filter out high-frequency noise above 10kHz. The gain of the amplification circuit can be automatically adjusted according to the signal strength, ensuring that the weak current signal can be accurately captured by the 16-bit analog-digital converter.

[0019] Further, the touch screen is horizontally embedded and installed, and can display the real-time running parameters of the main circuit and branch circuit, including three-phase voltage, three-phase current, insulation resistance, ground capacitance and fault state, and support Chinese and digital naming of branch circuit, with a response time ≤2S and a backlit screen time adjustable within 0-30min, and the screen can be clicked to realize screen lighting.

[0020] The touch screen adopts an industrial-grade capacitive screen, supports glove operation, and has a scratch-resistant and wear-resistant coating on the surface. The display interface adopts a modular layout, with the main area divided into main circuit overview and branch circuit details. The fault state is presented in the form of a red flashing icon combined with sound prompts. Chinese naming supports pinyin input method, with a maximum of 8 characters, meeting the circuit identification needs of scenarios such as workshops and office buildings.

[0021] Further, the output current of the relay actuator is 3.0A, the action time is ≤1S and adjustable, and the automatic and manual control modes can be switched, with the default mode being manual control. The alarm circuit of the monitoring terminal is an AC220V / 100W, and the alarm value of the insulation resistance of the main circuit and branch circuit can be set within the range of 0-999kΩ. When the insulation resistance is lower than the set value and the duration reaches the set leakage alarm delay time, the sound and light alarm is triggered.

[0022] The relay adopts a magnetic retention design, which can maintain the state without continuous power supply after action, reducing power consumption. In automatic control mode, the system will decide whether to trip immediately according to the fault level, and severe faults can avoid misoperation caused by transient interference.

[0023] Further, the zero sequence transformer and the current transformer are analog input, and the measurement range of the three-phase current of the main circuit is 0-400A, and the measurement range of the branch circuit current is 0-200A, with a measurement error ≤0.2%. The main circuit and branch circuit insulation resistance range is 0-999kΩ, the main circuit and branch circuit ground capacitance range is 0-9.99uF, the ground capacitance monitoring precision is ±5%, and the ground voltage measurement range is 0-450V.

[0024] The zero sequence transformer adopts an open-close structure, the aperture is 50mm, installation is facilitated without cutting off the cable, the core adopts high permeability permalloy, the collection sensitivity of a small current signal is ensured, the current transformer ratio is 400 / 5A and 200 / 5A, the secondary side output is connected to the branch circuit data terminal module through a shielded wire, and electromagnetic coupling with a strong current circuit is avoided.

[0025] Further, the communication interface of the monitoring terminal adopts a Modbus RS485 port, supports remote control authority management and communication isolation, can perform data transmission with operation and maintenance management, energy efficiency management, industrial control or an artificial intelligence platform, and the transmission content includes safety monitoring data of distribution network panel equipment and control line nodes.

[0026] The communication interface adopts photoelectric isolation design, the isolation voltage is 2500V, equipment damage caused by ground potential difference is effectively prevented, the remote control authority is divided into three levels of "administrator", "operator" and "viewer", different levels correspond to different operation authorities, transmission data adopts CRC check, and the integrity during long-distance transmission is ensured.

[0027] Further, the control module can inject a low-frequency alternating current synchronization signal with a frequency of 10-50Hz to the IT system, the signal voltage range is 0-450V, the monitoring terminal adopts an AC220V 50Hz 200W power supply, needs to be separately grounded to realize equipotential bonding, and supports system time setting and manual measurement function after fault branch circuit alarm.

[0028] The frequency of the low-frequency signal can be manually set through a touch screen or automatically adjusted by the system, when the system ground capacitance is greater than 5uF, the system is automatically switched to 50Hz to reduce the capacitive reactance influence, a surge protector is arranged at the power input end, lightning and other transient overvoltages are resisted, the separate grounding adopts a copper grounding electrode, the distance between the grounding electrode and other equipment grounding grids is greater than or equal to 5m, and ground interference is avoided.

[0029] The beneficial effects of the present application are: 1、in the present application, a low-frequency alternating current synchronization signal is injected through the control module, the zero sequence current is decomposed into 0° active component and 90° reactive component based on the signal, and insulation resistance and ground capacitance are accurately calculated based on a formula, the ground capacitance monitoring precision is greatly improved, the insulation resistance measurement error is greatly reduced, the misjudgment and missed judgment problems caused by capacitance interference of traditional equipment are solved, and reliable insulation state data is provided for complex IT systems.

[0030] 2、The independent data terminal module and address are configured for each sub-circuit in the application, the current, insulation resistance and ground capacitance data of each sub-circuit can be collected individually, when the insulation resistance of a sub-circuit is lower than the set threshold and lasts for the alarm delay time, the system triggers the sound-light alarm and displays the fault circuit in red on the touch screen, supports automatic and manual control of the fault circuit to be disconnected through the relay, compared with the traditional overall power-off troubleshooting, the fault processing time is greatly shortened, and the safety of distribution network is improved.

[0031] 3、The data collection, analysis calculation, control execution functions are integrated in the control module in the application, on-site edge side processing is realized, the real-time picture response time is less than or equal to 2S, the real-time requirement of power distribution control is met, and the platform is compatible with operation and maintenance management and industrial control through the Modbus RS485 interface, the detailed data of the distribution network panel equipment can be uploaded, the delay problem caused by the dependence of the traditional equipment main station is solved, and data support is provided for the upper system.

[0032] 4、The modular architecture is adopted in the application, the address of the sub-circuit data terminal module can be dynamically configured, the number of circuits can be expanded by adding modules, the control module can automatically adjust the frequency of the injected signal according to the ground capacitance of the system, the high-frequency signal is switched to in the large-capacitance system to reduce interference, for example, when the number of circuits is expanded from 12 to 30, only the sub-circuit data terminal module needs to be added and the new address needs to be configured, the system does not need to be reconstructed, the expansion cost is greatly reduced, and the needs of different scale IT distribution networks in industry, commerce and the like can be met. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are included to provide a further understanding of the application and constitute a part of the specification, which together with the embodiments of the application are used to explain the application and do not constitute a limitation on the application. In the drawings: Figure 1 A terminal system structure and information interaction relationship diagram of a low-voltage power distribution intelligent safety data monitoring terminal proposed in the application; Figure 2 A data acquisition system composition diagram of a low-voltage power distribution intelligent safety data monitoring terminal proposed in the application; Figure 3 A zero sequence current signal decomposition diagram structure schematic view of a low-voltage power distribution intelligent safety data monitoring terminal proposed in the application; Figure 4 A data monitoring schematic diagram of a low-voltage power distribution intelligent safety data monitoring terminal proposed in the application. DETAILED DESCRIPTION

[0034] In order to make the technical means and purposes and effects of the application easy to understand, the embodiments of the application will be described in detail below with reference to specific drawings. Example 1.

[0035] AsFigures 1-4 The low-voltage power distribution intelligent safety data monitoring terminal includes a control module, a signal module, at least one sub-circuit data terminal module, a zero sequence mutual inductor, a current transformer, and a relay actuator.

[0036] Specifically, the low-voltage power distribution intelligent safety data monitoring terminal is applied to an IT grounding system of an industrial workshop, the system includes 12 sub-circuits, and the overall architecture is composed of a control module, a signal module, 12 sub-circuit data terminal modules, 12 groups of zero sequence mutual inductors, 12 groups of current transformers, and 12 relay actuators. The modules are connected through shielded cables to reduce electromagnetic interference, and the specific connection relationship is as follows.

[0037] The wiring terminal of the control module includes a +12V power supply interface, a GND grounding interface, a touch screen interface, an infrared interface, and an RS485 bus interface.

[0038] The control module is connected with the touch screen through an internal communication line, the touch screen is installed in a horizontal embedded mode, the panel opening size is 265mm (length) x 168mm (height), and parameter setting and state checking can be realized through touch operation.

[0039] The signal module is connected with the 12 sub-circuit data terminal modules through a 485 bus, an isolation transformer in the signal module can effectively isolate power grid interference, and a signal processing unit includes a filter circuit and an operational amplifier, which can preprocess the uploaded current signal. The detailed preprocessing steps are as follows: First, high-frequency noise is filtered through a low-pass filter, and then the weak signal is amplified to the range that can be collected by the ADC through the amplifier, and then analog-to-digital conversion is performed.

[0040] It should be noted that each sub-circuit data terminal module is connected with one zero sequence mutual inductor and one current transformer, the zero sequence mutual inductor is sleeved on the outside of the sub-circuit cable and used for collecting zero sequence current signals, and the current transformer is connected in series in the sub-circuit and used for collecting three-phase current signals. The module decomposes the collected zero sequence current signal into 0° active current component and 90° reactive current component, the decomposition process is based on the transmitted synchronization signal, and the decomposition is realized through an internal orthogonal decomposition algorithm, wherein the 0° component reflects the active current Ir caused by the ground leakage resistance, and the 90° component reflects the reactive current Ic caused by the ground distributed capacitance. After the decomposition is completed, the module uploads Ir and Ic with the address information of the module to the signal module through the 485 bus.

[0041] Secondly, the control module injects an alternating current synchronization signal with a frequency of 20Hz into the IT system through an internal low-frequency signal source when the system is running, the range of signal voltage U is 0-450V, and the actual injection value is automatically adjusted according to the system working condition.

[0042] The internal data calculation unit receives the forwarded Ir and Ic data, and then calculates the insulation resistance and ground capacitance of each branch circuit based on the following formula: Insulation resistance (unit: MΩ, where U is the current injected signal voltage, and Ir is the 0° active current); Ground capacitance (unit: uF, where Ic is the 90° reactive current, and f is the injected signal frequency).

[0043] The calculation results are transmitted to the touch screen in real time, and the main page display content includes: system time, main circuit three-phase voltage, total three-phase current, each branch circuit current, insulation resistance and ground capacitance of the main circuit and branch circuit.

[0044] It should be noted that when the insulation resistance of a branch circuit is lower than the set alarm value and the duration reaches the set leakage alarm delay time, the system triggers an audible and light alarm, and the touch screen displays a red display at the corresponding branch circuit position.

[0045] The operator can manually measure the fault branch circuit parameters through the start leakage button of the touch screen, and also can adjust the alarm threshold through the parameter setting interface. After entering the parameter setting page, the system date and time, total current transformer range, liquid crystal screen bright screen time can be set, and the terminal address can also be modified.

[0046] The output current of the relay actuator is 3.0A, the action time is ≤1S, and the automatic and manual control mode switching is supported. When the automatic mode is selected, the system can automatically disconnect the fault branch circuit according to the alarm signal.

[0047] In addition, the terminal is connected with the operation and maintenance management platform of the workshop through the Modbus RS485 port, and the transmitted data includes the real-time running parameters and alarm information of the distribution network panel cabinet. Remote control authority management is supported during communication, and the data transmission safety is ensured through communication isolation design. The terminal power supply uses AC220V 50Hz 200W, and needs to be separately grounded to realize equipotential bonding during installation, so as to avoid ground interference affecting the measurement accuracy.

[0048] Example 2 As shown in Figures 1-4 , the terminal is applied to a large IT system containing 30 branch circuits, and the difference from example 1 is: The embodiment has the following extensions and optimizations in module connection and running logic: In terms of module connection, due to the increase in the number of sub-circuits, a star branch connection method using RS485 bus is adopted, with each branch connecting up to 10 sub-circuit data terminal modules, and terminal matching resistors are added at both ends of the bus to reduce signal reflection and ensure the stability of data transmission. A data cache unit is added inside the signal module to temporarily store data uploaded by each sub-circuit data terminal module, avoiding processing delays caused by excessive data volume.

[0049] The frequency of the low-frequency AC synchronization signal injected by the control module can be automatically adjusted according to the size of the system ground capacitance, with a range of 10-50 Hz. When the system ground capacitance is large, the frequency is automatically switched to 50 Hz to reduce the impact of capacitance charging and discharging on insulation resistance measurement; when the ground capacitance is small, it is switched to 10 Hz to improve the sensitivity of the measurement. The touch screen supports page display function, with 30 sub-circuits displayed in 3 pages, page switching is realized by sliding the screen, and each sub-circuit can be set with Chinese name, which is convenient for operators to identify and manage.

[0050] The control module adopts a dual-MCU redundancy design, with the main MCU and standby MCU running the same program simultaneously and comparing data in real time. When the main MCU fails, the standby MCU automatically takes over system control within 50 ms, ensuring continuous operation of the system. Key parameters are not only stored in the local Flash memory, but also uploaded to the cloud server for backup in an encrypted manner. When local data is lost, it can be downloaded from the cloud for recovery, ensuring the safety and integrity of system parameters. In addition, the embodiment adds a fault self-diagnosis function, with the control module periodically detecting the communication and function of each sub-circuit data terminal module and signal module. When a module fault is detected, the address and fault type of the faulty module are displayed on the touch screen, and an appropriate alarm is issued, facilitating quick troubleshooting and maintenance for maintenance personnel.

[0051] In terms of data acquisition accuracy, the analog-to-digital conversion circuit of the module is optimized, with a higher-precision ADC chip used to further reduce the measurement error of the current signal to ≤0.2%. At the same time, a signal conditioning circuit is added between the zero sequence transformer and the module to preamplify and filter the weak zero sequence current signal, improving the signal-to-noise ratio.

[0052] Through these optimizations and extensions, the extended embodiment can more effectively meet the monitoring needs of large and complex IT power distribution systems, further improving the reliability, stability and measurement accuracy of the system, and providing stronger technical support for safe power distribution and efficient operation and maintenance of industrial parks.

[0053] In summary, the two embodiments above show in detail the specific application of the low-voltage power distribution intelligent safety data monitoring terminal in IT power distribution systems of different scales, and by specifying the connection mode and operation logic of each module, the technical features of the terminal in data acquisition, processing, analysis, control and communication are embodied, which can realize real-time monitoring and accurate control of key parameters such as insulation resistance and ground capacitance of the main and branch circuits of the IT system, meet the real-time, reliability and safety requirements of the power distribution circuit operation, effectively replace the traditional IT distribution network secondary equipment, and provide a practical solution for the intelligent management of low-voltage power distribution systems.

[0054] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A low-voltage power distribution intelligent safety data monitoring terminal, characterized in that, The device comprises a control module, a signal module, at least one branch circuit data terminal module, a zero sequence transformer, a current transformer and a relay actuator. The control module is in communication connection with the signal module and a touch screen, and the signal module is connected with each branch circuit data terminal module through a 485 bus. The output ends of the zero sequence transformer and the current transformer are connected with the input end of the branch circuit data terminal module, and the output end of the branch circuit data terminal module is connected with the relay actuator. The control module is used for sending a synchronization signal, a running monitoring and a control instruction, the signal module is used for processing sensor data and executing a control command, and the branch circuit data terminal module is used for collecting current signals and converting them into digital quantities.

2. The low-voltage power distribution intelligent safety data monitoring terminal according to claim 1, characterized in that, The control module adopts a high-performance 32-bit microcontroller MCU, which has a clock frequency of 48 MHz, integrates ADC, PWM, SCI, SPI and CAN peripherals, and has a built-in real-time operating system, supporting multi-task processing, interruption management and task scheduling.

3. The low-voltage power distribution intelligent safety data monitoring terminal according to claim 1, characterized in that, The branch circuit data terminal module can decompose the zero sequence current signal collected by the zero sequence transformer into a 0° active current component and a 90° reactive current component, wherein the 0° active current component is the active current caused by the ground leakage resistance, and the 90° reactive current component is the reactive current caused by the ground distributed capacitance, and the active current and the reactive current with address information are uploaded to the signal module through a 485 bus.

4. The low-voltage power distribution intelligent safety data monitoring terminal according to claim 3, characterized in that, The device further comprises a data calculation unit arranged in the control module, which is used for calculating the branch circuit insulation resistance and the ground capacitance based on the active current and the reactive current uploaded by the branch circuit data terminal module. The calculation formula of the insulation resistance is as follows: wherein R is the insulation resistance, U is the low-frequency alternating signal voltage between the control module and the ground, and Ir is the 0° active current. The calculation formula of the ground capacitance is as follows:

5. The low-voltage power distribution intelligent safety data monitoring terminal according to claim 1, characterized in that, wherein C is the ground capacitance, Ic is the 90° reactive current, and f is the injection signal frequency.

6. The low-voltage power distribution intelligent safety data monitoring terminal of claim 1, wherein The signal module comprises an isolation transformer, a signal processing unit and a communication interface, the signal processing unit can filter, amplify and analog-digital convert the current signal sent by the branch circuit data terminal module, can read and write the address of the branch circuit data terminal module, and can receive the operation command of the control module to control the circuit breaker in real time.

7. The low-voltage power distribution intelligent safety data monitoring terminal of claim 1, wherein The touch screen is horizontally embedded and installed, can display the real-time running parameters of the main circuit and the branch circuit, including three-phase voltage, three-phase current, insulation resistance, ground capacitance and fault state, supports Chinese and digital naming of the branch circuit, the response time is less than or equal to 2 seconds, the back light screen time can be adjusted within 0-30 minutes, and the screen is turned on by clicking. The output current of the relay actuator is 3.0 A, the action time is less than or equal to 1 second and can be adjusted, and the automatic and manual control modes can be switched, and the default mode is manual control. The alarm loop of the monitoring terminal is an AC220V / 100W, the insulation resistance alarm values of the main circuit and the branch circuit can be set within the range of 0-999kΩ, and when the insulation resistance is lower than the set value and the duration reaches the set leakage alarm delay time, the audible and visual alarm is triggered.

8. The low-voltage power distribution intelligent safety data monitoring terminal of claim 1, wherein, The zero sequence mutual inductor and the current transformer are analog input, wherein the main circuit three-phase current measurement range is 0-400A, the branch circuit current measurement range is 0-200A, and the measurement error is less than or equal to 0.2%; The main circuit and branch circuit insulation resistance range is 0-999kΩ, the main circuit and branch circuit ground capacitance range is 0-9.99uF, the ground capacitance monitoring precision is ±5%, and the ground voltage measurement range is 0-450V.

9. The low-voltage power distribution intelligent safety data monitoring terminal of claim 1, wherein, The communication interface of the monitoring terminal adopts a Modbus RS485 port, supports remote control authority management and communication isolation, can perform data transmission with operation and maintenance management, energy efficiency management, industrial control or an artificial intelligence platform, and the transmission content includes safety monitoring data of distribution network panel cabinet equipment and control line nodes.

10. The low-voltage power distribution intelligent safety data monitoring terminal of claim 1, wherein, The control module can inject a low-frequency alternating current synchronous signal with a frequency of 10-50Hz into the IT system, the signal voltage range is 0-450V, the monitoring terminal adopts an AC220V 50Hz 200W power supply, needs to be separately grounded to realize equipotential bonding, and supports system time setting and manual measurement function after fault branch circuit alarm.

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