Substation AC power supply system residual current on-line monitoring protection device

Abstract

The utility model relates to the technical field of residual current on-line monitoring, in particular to a residual current on-line monitoring and protecting device for an alternating current power supply system for a transformer substation, which comprises a residual current transformer unit, a 485 communication acquisition unit, a wireless LORA acquisition unit, a magnetism gathering iron core unit, a data gathering unit and a comprehensive monitoring management terminal, the magnetism gathering iron core unit and the residual current transformer unit are both arranged on an external cable to be monitored, the residual current transformer unit is electrically connected with the 485 communication acquisition unit and the wireless LORA acquisition unit, the wireless LORA acquisition unit is electrically connected with the comprehensive monitoring management terminal through the data collection unit, the magnetism gathering iron core unit is electrically connected with the wireless LORA acquisition unit, and the wireless LORA acquisition unit is electrically connected with the comprehensive monitoring management terminal through the data collection unit. The 485 communication acquisition unit is electrically connected with the comprehensive monitoring management terminal, and can measure the residual current of a plurality of lines at the same time and wirelessly transmit the residual current to the terminal for monitoring.

Description

Technical Field

[0001] The utility model relates to the technical field of residual current on-line monitoring, and particularly relates to a residual current on-line monitoring and protection device for the AC power supply system of a substation for station use. Background Technique

[0002] The residual current on-line monitoring and protection device for the AC power supply system of a substation for station use is a station internal power protection device integrating front-end current detection, intermediate current data acquisition and transmission, and terminal line distribution and current data display; through rectifying the residual current on-line protection function of the substation, the grounding methods of each level of distribution of the AC power supply for station use can be sorted out, grounded according to unified specifications, the self-switching function of the low-voltage self-switching equipment can be verified, the rated current of each level of AC and DC circuit breakers can be checked according to the grading specifications, a clear grading drawing of the internal power distribution of the station can be formed, the residual current values of each level can be monitored and displayed in real time, early warnings can be given for line insulation deterioration and equipment insulation faults according to the residual current values, and the safe and reliable operation of the internal electrical system of the station can be guaranteed. Once, a low-voltage AC cable fire occurred in a 500 kV substation, causing damage to the insulation of the DC cable, and finally resulting in the operation of two sets of 500 kV bus differential protections. Finally, it was found through investigation that there were mainly two reasons for the low-voltage AC cable fire: one was that when a metal short circuit occurred in the cable, the sensitivity of the protective circuit breaker was insufficient and it could not be opened in a short time, causing the cable to catch fire; the other was that when the cable suffered from insulation damage, creepage and arcing or short circuit to the armor occurred, it belonged to "high-resistance grounding", and the circuit breaker could not be opened, but at this time the temperature of the arc path or short circuit point was very high, causing the cable to catch fire. In response to the second type of problem, a solution for rectifying the residual current on-line protection function of the cable was proposed; the residual current on-line monitoring and protection device for the AC power supply system of a substation for station use mainly includes an industrial control computer, a GFSU, a display screen, a data acquisition module and a data receiving module; among them, the industrial control computer, the GFSU and the display screen are used as the background system to complete the processing and display of the collected current data; the data acquisition module and the data receiving module are used as the acquisition front end to complete the real-time acquisition and transmission of the current data.

[0003] Implementing online monitoring of residual current is a major part of the protection system design. Currently, there are two common ways to implement current detection devices: one is to install intelligent switches with residual current data acquisition functions at relevant nodes for automatic detection. The intelligent switches with residual current data acquisition functions have problems such as large volume, the need to cut off power during installation, which affects users' electricity consumption, no data networking function, no reuse function, and the data collected by each device can only be viewed independently, and it is impossible to browse and analyze the data of all nodes on a unified platform; the other is to use a clamp-on residual current ammeter for manual detection, which is the main tool for measuring the residual current value at present. It consists of two parts: a clamp-on meter head and a meter body. The clamp-on meter head is a residual current transformer that can be freely closed. Clamping the meter head on the measured line can obtain the residual current signal on the measured line, and then through conversion and analysis, finally, the measured value is displayed on the display screen of the meter body. When using a clamp-on residual current ammeter, there are problems such as poor battery life, no rain protection function, low data acquisition frequency, only being able to collect the residual current data that always exists, no data networking function, unable to browse and analyze the data of all nodes on a unified platform, and small memory that cannot support long-term operation and large-scale storage.

[0004] In summary, there is currently no intelligent residual current monitoring and protection system that can simultaneously measure the residual current of multiple lines and wirelessly transmit it to the terminal for monitoring. Most of the existing residual current detection and monitoring devices are for wired monitoring and manual measurement, and are not suitable for the intelligent monitoring of multiple lines in the substation. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide an intelligent residual current monitoring and protection system that can simultaneously measure the residual current of multiple lines and wirelessly transmit it to the terminal for monitoring.

[0006] To solve the above technical problem, the technical solution adopted by this utility model is:

[0007] A residual current online monitoring and protection device for the AC power supply system of a substation includes a residual current transformer unit, a 485 communication acquisition unit, a wireless LORA acquisition unit, a ferromagnetic core unit, a data aggregation unit, and a comprehensive monitoring and management terminal;

[0008] The ferromagnetic core unit and the residual current transformer unit are both arranged on the external cables to be monitored. The residual current transformer unit is electrically connected to the 485 communication acquisition unit and the wireless LORA acquisition unit respectively. The wireless LORA acquisition unit is electrically connected to the comprehensive monitoring and management terminal through the data aggregation unit. The ferromagnetic core unit is electrically connected to the wireless LORA acquisition unit. The 485 communication acquisition unit is electrically connected to the comprehensive monitoring and management terminal.

[0009] Further, the residual current transformer unit includes a plurality of current transformers. The input ends of the plurality of current transformers are all electrically connected to an external cable. The output ends of a part of the current transformers in the residual current transformer unit are all electrically connected to a 485 communication acquisition unit, and the output ends of another part of the current transformers in the residual current transformer unit are all connected to a wireless LORA acquisition unit.

[0010] Further, the 485 communication acquisition unit includes a first voltage conditioning circuit, a programmable analog switch circuit, a first MCU chip, and a first isolated 485 communication circuit. The input end of the first voltage conditioning circuit is electrically connected to the output end of the residual current transformer unit. The output end of the first voltage conditioning circuit is electrically connected to the input end of the programmable analog switch circuit. The first MCU chip is electrically connected to the programmable analog switch circuit and the first isolated 485 communication circuit respectively. The first isolated 485 communication circuit is electrically connected to the integrated monitoring and management terminal.

[0011] Further, the first voltage conditioning circuit includes a transformer T13, an operational amplifier U12, an operational amplifier U14, an RMS conversion chip U15, and an operational amplifier U16;

[0012] The primary winding of the transformer T13 is electrically connected to the output end of the residual current transformer unit. The two ends of the secondary winding of the transformer T13 are respectively electrically connected to the non-inverting input end and the inverting input end of the operational amplifier U12. The output end of the operational amplifier U12 is electrically connected to the non-inverting input end of the operational amplifier U14. The output end of the operational amplifier U14 is respectively electrically connected to the non-inverting input end and the inverting input end of the operational amplifier U16 through the RMS conversion chip U15. The output end of the operational amplifier U16 is electrically connected to the input end of the programmable analog switch circuit.

[0013] Further, the first isolated 485 communication circuit includes an isolation chip U4. The isolation chip U4 is electrically connected to the first MCU chip and the integrated monitoring and management terminal respectively.

[0014] Further, the wireless LORA acquisition unit includes a second voltage conditioning circuit, a second MCU chip, and a first LORA communication module;

[0015] The input end of the second voltage conditioning circuit is electrically connected to the output end of the residual current transformer unit. The output end of the second voltage conditioning circuit is electrically connected to the input end of the first LORA communication module through the second MCU chip. The output end of the first LORA communication module is electrically connected to the integrated monitoring and management terminal through a data aggregation unit.

[0016] Further, the data aggregation unit includes a second LORA communication module, a third MCU chip, and a second isolated 485 communication circuit;

[0017] The input end of the second LORA communication module is electrically connected to the wireless LORA acquisition unit, the output end of the second LORA communication module is electrically connected to the input end of the third MCU chip and the second isolated 485 communication circuit, and the output end of the second isolated 485 communication circuit is electrically connected to the integrated monitoring and management terminal.

[0018] Further, an industrial control computer and a display module are also included, and the industrial control computer is electrically connected to the integrated monitoring and management terminal and the display module respectively.

[0019] Further, a mobile terminal is also included, and the mobile terminal is electrically connected to the industrial control computer.

[0020] Further, an Ethernet interface chip is also included, and the industrial control computer and the integrated monitoring and management terminal are electrically connected through the Ethernet interface chip.

[0021] The beneficial effects of the present utility model are as follows:

[0022] In this solution, by setting a residual current transformer unit, a 485 communication acquisition unit, a wireless LORA acquisition unit, a magnet core unit, a data aggregation unit, and an integrated monitoring and management terminal, the residual current transformer unit collects and transmits current data to the 485 communication acquisition unit or the wireless LORA acquisition unit through the principle of electromagnetic induction; according to different user requirements, the residual current transformer unit can be connected to two different data acquisition units. One is when the user needs to perform wireless current acquisition, the current transformer is paired with a wireless LORA acquisition unit with LORA communication inside, and the other is when the user selects local current direct monitoring, the current transformer is paired with a 485 communication acquisition unit; the wireless LORA acquisition unit is connected to the magnet core unit to complete the design of passive power acquisition; the wireless LORA acquisition unit has the function of wireless communication, establishes communication with the data aggregation unit through wireless LORA technology, and uploads the current data obtained from the residual current transformer unit to the data aggregation unit through wireless LORA communication; the 485 communication acquisition unit is connected to the residual current transformer unit and the integrated monitoring and management terminal respectively through the RS485 communication method, and transmits the current data obtained by the residual current transformer unit to the integrated monitoring and management terminal to realize the measurement of residual current of multiple lines at the same time. Description of the Drawings

[0023] Figure 1 It is the connection block diagram of the residual current on-line monitoring and protection device for the substation station-use AC power supply system of the present utility model;

[0024] Figure 2This is the circuit schematic diagram of the first voltage conditioning circuit of the residual current on-line monitoring and protection device for the AC power supply system used in the substation of the present utility model;

[0025] Figure 3 This is the circuit schematic diagram of the first isolated 485 communication circuit of the residual current on-line monitoring and protection device for the AC power supply system used in the substation of the present utility model;

[0026] Label description:

[0027] 1. Residual current transformer unit;

[0028] 2. 485 communication acquisition unit; 201. First voltage conditioning circuit; 202. Program-controlled analog switch circuit; 203. First MCU chip; 204. First isolated 485 communication circuit;

[0029] 3. Wireless LORA acquisition unit; 301. Second voltage conditioning circuit; 302. Second MCU chip; 303. First LORA communication module;

[0030] 4. Concentrated magnetic core unit;

[0031] 5. Data aggregation unit; 501. Second LORA communication module; 502. Third MCU chip; 503. Second isolated 485 communication circuit;

[0032] 6. Integrated monitoring and management terminal;

[0033] 7. Industrial control computer;

[0034] 8. Display module;

[0035] 9. Mobile terminal;

[0036] 10. Cable. Specific implementation manner

[0037] To describe in detail the technical content, achieved purpose and effect of the present utility model, the following is described in conjunction with the implementation manner and accompanied by the drawings.

[0038] Please refer to Figure 1 , the technical solution adopted by the present utility model is:

[0039] A residual current on-line monitoring and protection device for the AC power supply system used in the substation includes a residual current transformer unit, a 485 communication acquisition unit, a wireless LORA acquisition unit, a concentrated magnetic core unit, a data aggregation unit and an integrated monitoring and management terminal;

[0040] Both the poly-magnet core unit and the residual current transformer unit are arranged on the cable to be monitored externally. The residual current transformer unit is electrically connected to the 485 communication acquisition unit and the wireless LORA acquisition unit respectively. The wireless LORA acquisition unit is electrically connected to the integrated monitoring and management terminal through the data aggregation unit. The poly-magnet core unit is electrically connected to the wireless LORA acquisition unit. The 485 communication acquisition unit is electrically connected to the integrated monitoring and management terminal.

[0041] As can be seen from the above description, the beneficial effects of the present utility model are as follows:

[0042] In this solution, by setting up the residual current transformer unit, 485 communication acquisition unit, wireless LORA acquisition unit, poly-magnet core unit, data aggregation unit and integrated monitoring and management terminal, the residual current transformer unit transmits the current data collected through the principle of electromagnetic induction to the 485 communication acquisition unit or the wireless LORA acquisition unit; according to different user requirements, the residual current transformer unit can be connected to two different data acquisition units. One is when the user needs to perform wireless current acquisition, the current transformer is paired with a wireless LORA acquisition unit with LORA communication inside. The other is when the user selects local current direct monitoring, the current transformer is paired with a 485 communication acquisition unit; the wireless LORA acquisition unit is connected to the poly-magnet core unit to complete the design of power supply without power source; the wireless LORA acquisition unit has the function of wireless communication, and establishes communication with the data aggregation unit through wireless LORA technology, and uploads the current data obtained from the residual current transformer unit to the data aggregation unit through wireless LORA communication; the 485 communication acquisition unit is connected to the residual current transformer unit and the integrated monitoring and management terminal respectively through the RS485 communication method, and transmits the current data obtained by the residual current transformer unit to the integrated monitoring and management terminal to realize the measurement of residual current of multiple lines at the same time.

[0043] Further, the residual current transformer unit includes a plurality of current transformers. The input ends of the plurality of current transformers are all electrically connected to the external cable. The output ends of a part of the current transformers in the residual current transformer unit are all electrically connected to the 485 communication acquisition unit. The output ends of another part of the current transformers in the residual current transformer unit are all connected to the wireless LORA acquisition unit.

[0044] As can be seen from the above description, by electrically connecting the output terminals of a part of the current transformers in the residual current transformer unit to the 485 communication acquisition unit, and the output terminals of another part of the current transformers in the residual current transformer unit to the wireless LORA acquisition unit, a residual detection display with dual-path mutual inductance can be realized. Most of the current detection devices on the market are for local detection and single-path wireless upload detection, and have poor battery life; the dual-path mutual inductance residual detection display has the advantages of local residual current liquid crystal display, wireless LORA data upload, and passive power supply, solving the problem of measuring the residual current of cables with separated phase and neutral lines, solving the problem of measuring the residual current at the power supply end of a dual-loop power supply system, and solving the problem of long-term power supply.

[0045] Further, the 485 communication acquisition unit includes a first voltage conditioning circuit, a programmable analog switch circuit, a first MCU chip, and a first isolated 485 communication circuit. The input end of the first voltage conditioning circuit is electrically connected to the output end of the residual current transformer unit, the output end of the first voltage conditioning circuit is electrically connected to the input end of the programmable analog switch circuit, the first MCU chip is electrically connected to the programmable analog switch circuit and the first isolated 485 communication circuit respectively, and the first isolated 485 communication circuit is electrically connected to the integrated monitoring and management terminal.

[0046] As can be seen from the above description, the residual current signal in the residual current transformer unit passes through the first voltage conditioning circuit. After the current signal is converted, amplified, and adjusted, it is transmitted to the first MCU chip through the programmable analog switch circuit for channel selection. The first MCU chip processes the signal and converts the data, and the final data is sent to the integrated monitoring and management terminal through the first isolated 485 communication circuit.

[0047] Further, the first voltage conditioning circuit includes a transformer T13, an operational amplifier U12, an operational amplifier U14, an RMS conversion chip U15, and an operational amplifier U16;

[0048] The primary winding of the transformer T13 is electrically connected to the output end of the residual current transformer unit. The two ends of the secondary winding of the transformer T13 are respectively electrically connected to the non-inverting input end and the inverting input end of the operational amplifier U12. The output end of the operational amplifier U12 is electrically connected to the non-inverting input end of the operational amplifier U14. The output end of the operational amplifier U14 is respectively electrically connected to the non-inverting input end and the inverting input end of the operational amplifier U16 through the RMS conversion chip U15. The output end of the operational amplifier U16 is electrically connected to the input end of the programmable analog switch circuit.

[0049] As can be seen from the above description, the transformer T13 converts the large current of the residual current transformer unit into a smaller current signal. The diode D5 is a TVS transient voltage suppressor, which protects the circuit from high-voltage transients (such as static electricity, lightning strikes, etc.). The functions of the diodes D3, D4, and D6 are rectification, preventing current backflow, and clamping at the diode D6. Through the voltage conversion and conditioning of the operational amplifiers U12 and U14 and the resistor network, the residual current AC signal is sent to the RMS conversion chip U15, which converts the AC signal into a DC voltage and sends it to the operational amplifier U16 to adjust the voltage to the range of 0 to 3.3V for output.

[0050] Further, the first isolated 485 communication circuit includes an isolation chip U4, and the isolation chip U4 is electrically connected to the first MCU chip and the integrated monitoring and management terminal respectively.

[0051] As can be seen from the above description, the first isolated 485 communication circuit converts the TTL level of the first MCU chip into the RS-485 bus standard through the isolation chip U4 to achieve long-distance and high-reliability communication.

[0052] Further, the wireless LORA acquisition unit includes a second voltage conditioning circuit, a second MCU chip, and a first LORA communication module;

[0053] The input end of the second voltage conditioning circuit is electrically connected to the output end of the residual current transformer unit. The output end of the second voltage conditioning circuit is electrically connected to the input end of the first LORA communication module through the second MCU chip. The output end of the first LORA communication module is electrically connected to the integrated monitoring and management terminal through the data aggregation unit.

[0054] Further, the data aggregation unit includes a second LORA communication module, a third MCU chip, and a second isolated 485 communication circuit;

[0055] The input end of the second LORA communication module is electrically connected to the wireless LORA acquisition unit. The output end of the second LORA communication module is electrically connected to the input end of the second isolated 485 communication circuit through the third MCU chip. The output end of the second isolated 485 communication circuit is electrically connected to the integrated monitoring and management terminal.

[0056] Further, an industrial computer and a display module are also included, and the industrial computer is electrically connected to the integrated monitoring and management terminal and the display module respectively.

[0057] Further, a mobile terminal is also included, and the mobile terminal is electrically connected to the industrial computer.

[0058] Further, it also includes an Ethernet interface chip, and the industrial control computer is electrically connected to the integrated monitoring and management terminal through the Ethernet interface chip.

[0059] As can be seen from the above description, the Ethernet interface chip provides a wired network connection function to realize data transmission and remote monitoring.

[0060] Please refer to Figures 1 to 3 shown, Embodiment 1 of the present utility model is:

[0061] Please refer to Figure 1 , a residual current on-line monitoring and protection device for the AC power supply system of a substation, including a residual current transformer unit 1, a 485 communication acquisition unit 2, a wireless LORA acquisition unit 3, a magnetic core unit 4, a data aggregation unit 5 and an integrated monitoring and management terminal 6;

[0062] Both the magnetic core unit 4 and the residual current transformer unit 1 are arranged on the external cable 10 to be monitored. The residual current transformer unit 1 is electrically connected to the 485 communication acquisition unit 2 and the wireless LORA acquisition unit 3 respectively. The wireless LORA acquisition unit 3 is electrically connected to the integrated monitoring and management terminal 6 through the data aggregation unit 5. The magnetic core unit 4 is electrically connected to the wireless LORA acquisition unit 3, and the 485 communication acquisition unit 2 is electrically connected to the integrated monitoring and management terminal 6.

[0063] In this embodiment, the magnetic core unit 1 uses a commonly used magnetic core on the market, such as a magnetic core with the model UF65-UU80.

[0064] The residual current transformer unit 1 includes a plurality of current transformers. The input ends of the plurality of current transformers are all electrically connected to the external cable 10. The output ends of a part of the current transformers (32 in this embodiment) in the residual current transformer unit 1 are all electrically connected to the 485 communication acquisition unit 2, and the output ends of another part of the current transformers in the residual current transformer unit 1 are all connected to the wireless LORA acquisition unit 3.

[0065] The 485 communication acquisition unit 2 includes a first voltage conditioning circuit 201 (32 channels in this embodiment), a programmable analog switch circuit 202, a first MCU chip 203 and a first isolated 485 communication circuit 204. The input end of the first voltage conditioning circuit 201 is electrically connected to the output end of the residual current transformer unit 1. The output end of the first voltage conditioning circuit 201 is electrically connected to the input end of the programmable analog switch circuit 202. The first MCU chip 203 is electrically connected to the programmable analog switch circuit 202 and the first isolated 485 communication circuit 204 respectively. The first isolated 485 communication circuit 204 is electrically connected to the integrated monitoring and management terminal 6.

[0066] In this embodiment, the 32 residual current signals of the 32 current transformers in the residual current transformer unit 1 respectively pass through 32 first voltage conditioning circuits 201. After the current signals are converted, amplified and adjusted, they are transmitted to the ADC acquisition pins of the first MCU chip 203 through a programmable analog switch circuit 202 (including 16 groups of programmable analog switches in this embodiment) for channel selection. The first MCU chip 203 processes the signals and converts the data, and the final data is sent to the integrated monitoring and management terminal 6 through the first isolation 485 communication circuit 204.

[0067] Please refer to Figure 2 , the circuit structures of each of the first voltage conditioning circuits 201 are the same. The first voltage conditioning circuit 201 includes a transformer T13, an operational amplifier U12, an operational amplifier U14, an RMS conversion chip U15, and an operational amplifier U16;

[0068] The primary winding of the transformer T13 is electrically connected to the output end of the residual current transformer unit 1. The two ends of the secondary winding of the transformer T13 are respectively electrically connected to the non-inverting input end and the inverting input end of the operational amplifier U12. The output end of the operational amplifier U12 is electrically connected to the non-inverting input end of the operational amplifier U14. The output end of the operational amplifier U14 is respectively electrically connected to the non-inverting input end and the inverting input end of the operational amplifier U16 through the RMS conversion chip U15. The output end of the operational amplifier U16 is electrically connected to the input end of the programmable analog switch circuit 202.

[0069] The first voltage conditioning circuit 201 further includes a diode D5, a resistor R21, a resistor R19, a resistor R22, a capacitor C20, a diode D3, a diode D4, a resistor R18, a diode D6, a resistor R20, a resistor R26, a resistor R28, a resistor R24, a capacitor C22, a capacitor C21, a resistor R25, a resistor R27, and a resistor R23. For the specific connection relationship between its various components, please refer to Figure 2 ;

[0070] The transformer T13 converts the large current of the residual current transformer unit 1 into a smaller current signal. The diode D5 is a TVS transient voltage suppressor to protect the circuit from high-voltage transients (such as static electricity, lightning strikes, etc.). The functions of the diodes D3, D4, and D6 are rectification to prevent current backflow and play a clamping role at the diode D6. Through the voltage conversion and conditioning of the operational amplifier U12, the operational amplifier U14, and the resistor network, the residual current AC signal is sent to the RMS conversion chip U15 to convert the AC signal into a DC voltage and send it to the operational amplifier U16 to adjust the voltage to the range of 0 - 3.3V for output.

[0071] Please refer toFigure 3 The first isolated 485 communication circuit 204 includes an isolation chip U4, and the isolation chip U4 is electrically connected to the first MCU chip 203 and the integrated monitoring and management terminal 6 respectively.

[0072] The first isolated 485 communication circuit 204 further includes a capacitor C1, a capacitor C2, a resistor R3, a resistor R4, a capacitor C7, a capacitor C8, a capacitor C3, a capacitor C4, a diode D1, a resistor R6, a capacitor C9, a capacitor C10, and a thermistor RT1. For the specific connection relationship between its various components, please refer to Figure 3 ;

[0073] The first isolated 485 communication circuit 204 converts the TTL level of the first MCU chip 203 into the RS-485 bus standard through the isolation chip U4 to achieve long-distance and high-reliability communication. Among them, the capacitors C1, C2, C7, and C8 are power decoupling capacitors used to filter out high-frequency noise on the power supply to ensure the stability of the power supply; the diode D1 (model: P6SMB6.8CA) is a transient voltage suppression diode used to protect the RS-485 bus interface from damage by electrical transients and spike voltages; the thermistor RT1 (model: SPMZB-10) can increase the resistance value when the current is too large to protect the circuit from damage by overcurrent; the resistor R6 is a current-limiting resistor used to limit the current magnitude; 485_A and 485_B are the A and B differential signal lines of the RS-485 bus, and long-distance data communication is carried out through these pins.

[0074] The wireless LORA acquisition unit 3 includes a second voltage conditioning circuit 301, a second MCU chip 302, and a first LORA communication module 303;

[0075] The input end of the second voltage conditioning circuit 301 is electrically connected to the output end of the residual current transformer unit 1. The output end of the second voltage conditioning circuit 301 is electrically connected to the input end of the first LORA communication module 303 through the second MCU chip 302. The output end of the first LORA communication module 303 is electrically connected to the integrated monitoring and management terminal 6 through the data aggregation unit 5.

[0076] In this embodiment, the circuit structure of the second voltage conditioning circuit 301 is the same as that of the first voltage conditioning circuit 201.

[0077] In this embodiment, the first LORA communication module 303 includes a first LORA chip of model SX1268;

[0078] In this embodiment, the model number of the second MCU chip 302 is STM32F103. The chip with the model number STM32F103 is a low-power microcontroller, which is used to collect and process signals from the first voltage conditioning circuit 201. The ADC0 pin of the second MCU chip 302 is used for analog-to-digital conversion, converting the conditioned analog signal from the current transformer into a digital signal. The second MCU chip 302 is also responsible for data communication with the first LORA communication module 303 through the SPI interface, and wirelessly sending the collected current data to the data aggregation unit 5.

[0079] The wireless LORA acquisition unit 3 is mainly used to convert the current signal detected by the residual current transformer unit into a wireless signal and perform long-distance transmission through the first LORA communication module 303.

[0080] The data aggregation unit 5 includes a second LORA communication module 501, a third MCU chip 502, and a second isolated 485 communication circuit 503.

[0081] The input end of the second LORA communication module 501 is electrically connected to the wireless LORA acquisition unit 3. The output end of the second LORA communication module 501 is electrically connected to the input end of the third MCU chip 502 and the second isolated 485 communication circuit 503. The output end of the second isolated 485 communication circuit 503 is electrically connected to the integrated monitoring and management terminal 6.

[0082] In this embodiment, the circuit structure of the second isolated 485 communication circuit 503 is the same as that of the first isolated 485 communication circuit 204.

[0083] In this embodiment, the model number of the third MCU chip 502 is STM32F103.

[0084] In this embodiment, the second LORA communication module 501 includes a second LORA chip with the model number SX1268, collects the data sent by the first LORA chip using the modbus protocol, reads the data through the SPI bus of the third MCU chip 502, and uploads the data to the integrated monitoring and management terminal 6 through the 485 bus via the second isolated 485 communication circuit 503.

[0085] It also includes an industrial computer 7 (model number CE-IED-4000) and a display module 8. The industrial computer 7 is electrically connected to the integrated monitoring and management terminal 6 and the display module 8 respectively.

[0086] It also includes a mobile terminal 9 (model number CE-ZYW-100M). The mobile terminal 9 is electrically connected to the industrial computer 7.

[0087] It also includes an Ethernet interface chip (model: W5500), and the industrial control computer 7 is electrically connected to the integrated monitoring and management terminal 6 through the Ethernet interface chip; the Ethernet interface chip provides a wired network connection function to realize data transmission and remote monitoring; the integrated monitoring and management terminal 6 is also electrically connected to a KEY button function module to provide user input and control functions; the display module 8 includes an LCD / LVDS display screen interface and a display screen, and the LCD / LVDS display screen interface is used to connect and drive the display screen to display monitoring data and system status in real time; the integrated monitoring and management terminal 6 is also electrically connected to a USB2.0 interface to provide expansion and peripheral connection functions; the integrated monitoring and management terminal 6 is also electrically connected to a UART interface for serial communication to connect debugging devices or other external modules; the integrated monitoring and management terminal 6 is also electrically connected to a 4G communication module to provide mobile data communication functions, which is applicable to scenarios where wired networks cannot be accessed; the overall function of the integrated monitoring and management terminal 6 is to collect and upload the current signals detected by multiple current transformers to the industrial control computer 7 through a multiple-channel voltage conditioning unit (using RS-485 or LoRa wireless mode).

[0088] This solution is applicable to the monitoring of the residual current of single-phase circuits (or devices), three-phase circuits (or devices), single-phase and three-phase hybrid devices, and the residual current when the phase and neutral wires of hybrid devices are separated.

[0089] The residual current transformer unit 1 is the bottom component of the residual current on-line monitoring and protection system. The current transformer is installed on the cable 10 to be monitored. For armored cables, the armored cable must be grounded at one end. The current transformer is clamped outside the cable armor in the cable trench of the cable 10. The armored shielding layer is wound out from inside the current transformer. The current transformer collects and transmits current data to the 485 communication acquisition unit 2 or the wireless LORA acquisition unit 3 through the principle of electromagnetic induction. According to different user requirements, the current transformer can be connected to two different data acquisition units. One is when the user needs to perform wireless current acquisition, the current transformer is paired with the wireless LORA acquisition unit 3 with LORA communication inside. The other is when the user selects local current direct monitoring, the current transformer is paired with the 485 communication acquisition unit 2. The wireless LORA acquisition unit 3 is connected to the magnet core unit 4 to complete the design of passive power acquisition. The magnet core unit 4 sleeves the circular iron core on the cable 10. The magnetic core senses the magnetic field around the cable 10 and induces electrical energy through the magnetic ring coil. The electrical energy reaches the power supply system inside the wireless LORA acquisition unit 3 through the coil end to supply power to it. The wireless LORA acquisition unit 3 has the function of wireless communication and establishes communication with the data aggregation unit 5 through wireless LORA technology, and uploads the current data obtained from the residual current transformer unit 1 to the data aggregation unit 5 through wireless LORA communication. The data aggregation unit 5 has two communication methods, one is wireless LORA communication, and the other is RS485 communication. The wireless LORA communication is to establish a connection with the wireless LORA acquisition unit 3 to complete the aggregation of current data. The RS485 communication is to establish a connection with the integrated monitoring and management terminal 6, and transmit the current data aggregated from the wireless LORA acquisition unit 3 to the integrated monitoring and management terminal 6 through the RS485 communication method. The 485 communication acquisition unit 2 is connected to the residual current transformer unit 1 and the integrated monitoring and management terminal 6 respectively through the RS485 communication method, and transmits the current data obtained by the residual current transformer unit 1 to the integrated monitoring and management terminal 6. The integrated monitoring and management terminal 6 is a modern high-tech product intelligent device integrating on-line residual current measurement, data acquisition, data analysis and control functions. It provides a communication interface that can be connected to the computer monitoring system, supports the RS485 interface MODBUS-RTU communication protocol, the communication baud rate can be set, and an optional Ethernet communication interface is available. It establishes connections with the data aggregation unit 5 and the 485 communication acquisition unit 2 through the RS485 communication method, receives and processes the current data transmitted by the data aggregation unit 5 and the 485 communication acquisition unit 2. At the same time, the integrated monitoring and management terminal 6 is connected to the industrial control computer 7 through a network cable, and uploads the received and processed current data to the industrial control computer 7. The industrial control computer 7 realizes the design of the residual current monitoring software. Through the residual current monitoring software, the current data, the current alarm situation, the current alarm history and the current historical data can be viewed.The display module 8 is connected to the industrial control computer 7 via VGA to complete the display of the residual current monitoring software designed by the industrial control computer 7; the mobile terminal 9 is a portable monitoring device, and the interface of the residual current monitoring software is consistent with that of the industrial control computer 7 to achieve the function of remote monitoring; the mobile terminal 9 and the industrial control computer 7 establish communication through the cloud server. First, the industrial control computer 7 uploads the current data to the cloud server, then the mobile terminal 9 obtains the current data through the cloud server, and finally the residual current is monitored on the residual current monitoring software of the mobile terminal. By rectifying the on-line protection function of the residual current in the substation, the grounding methods of each level of distribution power supply in the station service alternating current can be sorted out, grounded according to unified specifications, the self-switching function of the low-voltage automatic switching device can be verified, the rated current of each level of AC and DC circuit breakers can be checked according to the grading specifications, a clear in-station distribution grading drawing can be formed, the residual current values of each level can be monitored and displayed in real time, and the insulation deterioration of the line and the insulation fault of the equipment can be warned in advance according to the residual current value to ensure the safe and reliable operation of the in-station electrical system.;

[0090] This solution can complete the design of the Residual Current On-line Monitoring and Protection System APP by using Labview 2020 as the development platform; the operation steps of the Residual Current On-line Monitoring and Protection System APP are as follows:

[0091] The first step is to turn on the industrial control computer 7's operating system. After booting up, open the monitoring software and enter the monitoring software login interface. After entering the account and password on the monitoring software login interface, enter the home page of the monitoring software. The home page of the monitoring software is set with function blocks for online display of monitoring devices, display of alarm quantity and level, and display of running time. The device online function block can show how many remaining current aggregation units are currently working. The alarm quantity and level function block shows whether the operating state of the device is abnormal and can prompt the alarm level. The running time function block shows how long the device has been working from the start of operation to the current viewing time. The home page interface is also designed with a function menu selection module including: home page unit, device unit, configuration unit, alarm unit, report unit, and exit unit. The function of the home page unit is to switch to the home page display when running under other function modules. After entering the device unit, any online device can be selected on the device interface. Click on the device details selection display function to view all real-time data of the online device. After selecting to enter the configuration unit, the configuration is an intuitive diagram drawn according to the in-station topology diagram. The remaining current of each branch will be displayed on each branch. It is divided into two parts: indoor and outdoor. Under normal circumstances, it is displayed in green. When the remaining current of a certain branch increases and exceeds the set threshold, the color will be displayed in red. Click on "Details" to view the name of each branch. Click on "Outdoor Browsing Diagram" to view the remaining current situation of each outdoor terminal box. After selecting to enter the alarm unit, the alarm interface will display the current alarm status. When there is an alarm, the alarm quantity will be displayed on the alarm navigation bar. The alarm location, start time, and alarm reason can be viewed in the device alarm list. After selecting to enter the report unit, the report interface can display various alarm and remaining current historical data, and at the same time, the historical curve can be switched to facilitate users to more directly observe the historical data. After selecting the exit unit, exit the remaining current monitoring software.

[0092] Compared with the existing technology, the advantages of the remaining current online monitoring and protection device for the substation station service AC power supply system designed in this solution are as follows:

[0093] 1. This solution designs a remaining current detector with dual-path mutual inductance. Most of the current detection devices on the market are for local detection and single-path wireless upload detection, and have poor battery life. The dual-path mutual inductance remaining current detector has the advantages of local remaining current liquid crystal display, wireless LORA data upload, and passive power extraction, solving the problem of measuring the remaining current of cables with separated phase and neutral lines, solving the problem of measuring the remaining current at the power supply end of a double-loop power supply system, and the problem of long-term power supply.

[0094] 2. This solution measures the residual current of the armored cable by using a wiring method that winds the shielding layer of the armored cable out of the current transformer. Currently, the common measurement method for armored multi-core cables is to measure each single core one by one at the cable port, which wastes manpower and material resources. This solution saves the use of current transformers and greatly reduces the cost of detecting the residual current of armored cables.

[0095] 3. The data of each residual current detection unit is centralized to the central display unit. The central display unit displays the residual current of the line and equipment according to the topological diagram of the in-station distribution line structure. The magnitude and change of the residual current are clear at a glance, and historical data can be traced for a long time. Combined with the background monitoring software, it can manage the equipment at all levels of the substation more perfectly.

[0096] In summary, an on-line monitoring and protection device for the residual current of the AC power supply system used in a substation provided by the present utility model includes a residual current transformer unit, a 485 communication acquisition unit, a wireless LORA acquisition unit, a magnetic core unit, a data aggregation unit, and a comprehensive monitoring and management terminal. The residual current transformer unit collects and transmits current data to the 485 communication acquisition unit or the wireless LORA acquisition unit through the principle of electromagnetic induction. According to different user requirements, the residual current transformer unit can be connected to two different data acquisition units. One is when the user needs to perform wireless current acquisition, the current transformer is paired with a wireless LORA acquisition unit with LORA communication inside. The other is when the user selects local current direct monitoring, the current transformer is paired with a 485 communication acquisition unit. The wireless LORA acquisition unit is connected to the magnetic core unit to complete the design of passive power acquisition. The wireless LORA acquisition unit has the function of wireless communication and establishes communication with the data aggregation unit through wireless LORA technology, and uploads the current data obtained from the residual current transformer unit to the data aggregation unit through wireless LORA communication. The 485 communication acquisition unit is connected to the residual current transformer unit and the comprehensive monitoring and management terminal respectively through the RS485 communication method, and transmits the current data obtained by the residual current transformer unit to the comprehensive monitoring and management terminal to realize the measurement of the residual current of multiple lines at the same time.

[0097] The above are only the embodiments of the present utility model, and do not limit the patent scope of the present utility model accordingly. Any equivalent transformation made by using the content of the specification and drawings of the present utility model, or directly or indirectly applied in the related technical fields, shall be equally included in the patent protection scope of the present utility model.

Claims

1. An on-line monitoring and protection device for residual current of the AC power supply system used in a substation, characterized in that, It includes a residual current transformer unit, a 485 communication acquisition unit, a wireless LORA acquisition unit, a magnetic core unit, a data aggregation unit, and an integrated monitoring and management terminal; The magnetic core unit and the residual current transformer unit are both arranged on the cable to be monitored externally. The residual current transformer unit is electrically connected to the 485 communication acquisition unit and the wireless LORA acquisition unit respectively. The wireless LORA acquisition unit is electrically connected to the integrated monitoring and management terminal through the data aggregation unit. The magnetic core unit is electrically connected to the wireless LORA acquisition unit. The 485 communication acquisition unit is electrically connected to the integrated monitoring and management terminal.

2. The residual current on-line monitoring and protection device for the AC power supply system of a substation according to claim 1, characterized in that The residual current transformer unit includes several current transformers. The input ends of several current transformers are all electrically connected to the external cable. The output ends of a part of the current transformers in the residual current transformer unit are all electrically connected to the 485 communication acquisition unit. The output ends of another part of the current transformers in the residual current transformer unit are all connected to the wireless LORA acquisition unit.

3. The residual current on-line monitoring and protection device for the AC power supply system of a substation according to claim 1, characterized in that, The 485 communication acquisition unit includes a first voltage conditioning circuit, a programmable analog switch circuit, a first MCU chip, and a first isolated 485 communication circuit. The input end of the first voltage conditioning circuit is electrically connected to the output end of the residual current transformer unit. The output end of the first voltage conditioning circuit is electrically connected to the input end of the programmable analog switch circuit. The first MCU chip is electrically connected to the programmable analog switch circuit and the first isolated 485 communication circuit respectively. The first isolated 485 communication circuit is electrically connected to the integrated monitoring and management terminal.

4. The residual current on-line monitoring and protection device for the substation AC power supply system according to claim 3, characterized in that, The first voltage conditioning circuit includes a transformer T13, an operational amplifier U12, an operational amplifier U14, an effective value conversion chip U15, and an operational amplifier U16; The primary winding of the transformer T13 is electrically connected to the output end of the residual current transformer unit. The two ends of the secondary winding of the transformer T13 are respectively electrically connected to the non-inverting input end and the inverting input end of the operational amplifier U12. The output end of the operational amplifier U12 is electrically connected to the non-inverting input end of the operational amplifier U14. The output end of the operational amplifier U14 is respectively electrically connected to the non-inverting input end and the inverting input end of the operational amplifier U16 through the effective value conversion chip U15. The output end of the operational amplifier U16 is electrically connected to the input end of the programmable analog switch circuit.

5. The residual current on-line monitoring and protection device for the substation AC power supply system according to claim 3, characterized in that, The first isolated 485 communication circuit includes an isolation chip U4. The isolation chip U4 is electrically connected to the first MCU chip and the integrated monitoring and management terminal respectively.

6. The residual current on-line monitoring and protection device for the substation's AC power supply system according to claim 1, characterized in that, The wireless LORA acquisition unit includes a second voltage conditioning circuit, a second MCU chip, and a first LORA communication module; The input end of the second voltage conditioning circuit is electrically connected to the output end of the residual current transformer unit. The output end of the second voltage conditioning circuit is electrically connected to the input end of the first LORA communication module through the second MCU chip. The output end of the first LORA communication module is electrically connected to the integrated monitoring and management terminal through the data aggregation unit.

7. The residual current on-line monitoring and protection device for the AC power supply system of a substation station according to claim 1, characterized in that, The data aggregation unit includes a second LORA communication module, a third MCU chip, and a second isolated 485 communication circuit; The input end of the second LORA communication module is electrically connected to the wireless LORA acquisition unit, the output end of the second LORA communication module is electrically connected to the input end of the third MCU chip and the second isolated 485 communication circuit, and the output end of the second isolated 485 communication circuit is electrically connected to the integrated monitoring and management terminal.

8. The residual current on-line monitoring and protection device for the substation AC power supply system according to claim 1, characterized in that, It further includes an industrial computer and a display module, and the industrial computer is electrically connected to the integrated monitoring and management terminal and the display module respectively.

9. The residual current on-line monitoring and protection device for the substation AC power supply system according to claim 8, characterized in that, It further includes a mobile terminal, and the mobile terminal is electrically connected to the industrial computer.

10. The residual current on-line monitoring and protection device for the AC power supply system of a substation according to claim 9, characterized in that, It further includes an Ethernet interface chip, and the industrial computer and the integrated monitoring and management terminal are electrically connected through the Ethernet interface chip.

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