The present invention will be described in detail below with reference to the drawings and specific embodiments.
 The structure of an embodiment of the monitoring system of the present invention, such as figure 1 As shown, it includes a repeater 2, a converter 3, and a local workstation 4 connected in sequence. The repeater 2 is also connected to multiple monitoring extensions 1. The repeater 2 uses an RS-485 repeater, and the converter 3 Use RS-485 converter.
 The structure of the monitoring extension 1 in the monitoring system of the present invention, such as figure 2 As shown, the microcontroller 5 is included. The microcontroller 5 is connected to the LCD 6, the key module 7, the temperature and humidity sensor 8, the serial communication interface 9, the wireless receiving module 10, the buzzer 13, the indicator light 14 and the relay 15. The wireless receiving module 10 is connected to the 9 wireless temperature sensor nodes 11 wirelessly, and the 9 wireless temperature sensor nodes 11 are connected to the induction power supply 12 respectively.
 A set of monitoring extension 1 contains 9 wireless temperature sensor nodes 12, which complete the monitoring of 9 contacts and cabinet temperature, and 9 wireless temperature sensor nodes 12 simultaneously send the collected information and data to the wireless receiving module 10 on the extension , The wireless receiving module 10 sends the collected information data to the microcontroller 5 through the serial port, and each wireless temperature sensor node 12 sends an 8-byte data packet every second, and each set of monitoring extensions There is only one microcontroller 5 in 1, and the speed of microcontroller 5 is required to be very fast, so microcontroller 5 uses C8051F020http://www.ic37.com/hot/C8051F020.htm microcontroller, which is a mixed signal SoC Type 8-bit single-chip microcomputer with high integration level and pipeline instruction structure; 70% of the instruction execution time is one or two system clock cycles, and the speed can reach 25MIPS (when the clock frequency is 25MHz), which can realize real-time monitoring of wireless temperature sensors The information sent by the node 11 is processed. Monitoring extension 1 is connected to local workstation 4 through RS485 or CAN bus.
 The wireless receiving module 10 receives the information data transmitted by the wireless temperature sensor node 11, and transmits the received information data to the microcontroller 5. The microcontroller 5 receives the information and data input from the wireless receiving module 10, and also receives the information and data installed in the high voltage For the temperature information collected by the temperature and humidity sensor 8 of the switchgear cabinet, the microcontroller 5 performs a difference operation on the two received information, calculates the temperature rise value of the switchgear, and displays the temperature rise value on the liquid crystal display 6. The microcontroller 5 also needs to compare the temperature rise value with the pre-set warning value and alarm value. When the calculated temperature rise value is higher than the preset value, the microcontroller 5 opens the high-voltage switch installed in the high-voltage switch through the relay 15. The indicator 14 on the cabinet body and the buzzer 13 are turned on to give an early warning or alarm to remind the inspector to take corresponding measures.
 The wireless receiving module 10 realizes the wireless communication between the contact temperature monitoring node and the monitoring extension 1, which is equivalent to a full-function device (FFD) in the ZigBee network. The wireless receiving module 10 is vertically inserted on the main circuit board (due to the wireless receiving module It is a high-frequency circuit board, which can be inserted vertically on the main circuit board to reduce its impact on the main circuit board). Its structure is as follows image 3 As shown, it includes a microprocessor 16, a ZigBee physical layer chip 17, and an antenna 19 connected in sequence. The microprocessor 16 and the wireless module 17 are respectively connected to the power module 18.
 The microprocessor 16 uses MC9S08Q68. The ZigBee physical layer chip 17 uses MC13192.
 The wireless temperature sensor node 11 is equivalent to a reduced function device (RFD) in the ZigBee network, and is composed of a wireless module 17, a DS18B20 digital temperature sensor, and a power module 18.
 The 9-channel wireless temperature sensor node 11 and the wireless receiving module 10 form a small ZigBee network. The ZigBee network uses the ZigBee protocol stack with reduced functions. Its main functions include SPI interface read and write operations, ZigBee chip initialization, data transmission, and data transmission. Reception, CCA detection, PHY data structure generation and MAC layer data structure generation, etc. The ZigBee protocol stack can form a star network to realize the basic data transmission function of the monitoring system. The MC13192 adopted by the wireless module 17 has a collision avoidance strategy and an idle channel energy evaluation strategy, so that the monitoring extension 1 in a fixed area will not misreceive or not receive the information sent by the wireless temperature sensor node 11 of a branch.
The power module 18 is composed of an induction coil and a rectifier filter circuit. The induction coil is composed of iron core and winding wire. The entire induction coil is cast and encapsulated in epoxy resin and then sleeved on the contact arm. Since the current flowing through the contact of the high-voltage switchgear is an alternating current, the induction coil is (Equivalent to a transformer) takes electricity from the primary current loop, generates an induced current, and delivers the induced current to the rectifier filter circuit. The rectifier filter circuit rectifies and filters the input induced current to provide the wireless module 17 with a voltage of 3.3V. After testing, the primary loop current of the induction coil is within the range of 40A~8000A. The induction coil can work stably. When the primary loop current of the induction coil is less than 40A, for high-current and high-voltage equipment, it is considered that the contact does not generate heat. Therefore, the induction coil When the primary loop current is less than 40A, there is no need to detect the temperature of the contact, and the wireless temperature sensor node 11 does not need to work at this time. The structure and design parameters of the iron core and the coil are determined according to the shape and size of the contact and the outer shape of the contact arm.
 The DS18B20 digital temperature sensor in the power supply module 18 is connected to the power supply board through a high-voltage shielded wire, and provides a 9-bit temperature reading indicating the temperature of the measured device. The temperature information of the measured device is sent to or from the temperature sensor through a single-wire interface, and only one wire (and ground) is required to be connected between the microprocessor 16 and the DS18B20 digital temperature sensor. The power required for reading, writing and completing the temperature conversion of the temperature sensor is provided by the data line itself, without the need for an external power supply. Its measurement range is from -55°C to +125°C, with an incremental value of 0.5°C.
 There is an electrically erasable programmable read-only memory AT24C02 in the power module of the wireless temperature sensor node 11, which is used to store the address of the wireless temperature sensor node 11, and the address can be modified multiple times.
 High-voltage switchgear operates in a high-voltage, high-current environment, and the moment of an accident in the power transmission and transformation system, there are often strong electromagnetic transient processes, which produce strong electric fields, strong magnetic fields and strong electromagnetic interference, which are not conducive to microelectronics systems And weak signal processing. The wireless temperature sensor node 11 is close to the contacts of the circuit breaker. In order to avoid the interference of strong electric field, strong magnetic field and strong electromagnetic, the wireless temperature sensor node 11 is cast and encapsulated in epoxy resin, using the high dielectric properties of the epoxy resin system. The excellent performance of resistance to surface leakage and arc resistance, plays a very good role in isolation. The DS18B20 temperature sensor in the wireless temperature sensor node 11 extends from the epoxy resin and is directly fixed on the contact arm of the contact to be tested. It is at the same potential as the temperature measurement point, reducing the influence of electric field, and quickly and accurately sensing the temperature of the contact Variety. In order to eliminate the interference of random factors, using the characteristics of relatively slow temperature change of the contact, the temperature signal of the detection point is repeatedly received and collected multiple times to eliminate abnormal data to ensure the reliability of the data.
 The program flow chart of monitoring extension 1, such as Figure 4 Shown. The process is an infinite loop. The wireless temperature sensor node 11 and the temperature and humidity sensor 8 continuously monitor the status of the switch cabinet, contacts and switch cabinet buttons, and input the monitored information into the microcontroller 5 and microcontroller 5. The received information is processed, and at the same time, corresponding instructions can be input to the microcontroller 5 through the button module 7, so that the microcontroller 5 outputs various control signals in real time, and finally clears the watchdog counter to confirm the normal operation of the system.
 The system presets that the alarm priority is higher than the early warning priority. As long as the temperature rise value of the received contact is higher than the alarm value, it will directly alarm. Every time an early warning or alarm signal (early warning or warning light flashes on the front panel) is issued, the system returns to the monitoring status for query and judgment. After an early warning or alarm, the temperature reached at the gateway node is lower than the pre-set early warning or alarm value 2? Below, the indicator light used for early warning or alarm will be extinguished, which prevents the early warning or alarm indicator from flashing randomly due to repeated temperature changes.
 The working process of the monitoring system of the present invention:
 The monitoring extension 1 first receives the parameter data sent by the host computer through the serial communication interface 9, and displays the received data on the liquid crystal display 6. At the same time, the liquid crystal display 6 displays the actual temperature and the actual temperature of the contact transmitted by the wireless temperature sensor node 11 The difference between the cabinet temperature and the external environmental temperature and humidity monitored by the temperature and humidity sensor 8 are controlled by the microcontroller 5 to control the buzzer 13 to sound and the indicator 14 to emit light according to the set contact temperature value to realize early warning and error alarm. And through the serial communication interface 9 to report alarm information and communication to the local workstation 4, report query temperature, status information and change the system temperature settings. The 6-digit keyboard data entry is completed through the key module 7; power is provided to the temperature and humidity sensor 8 and information collection is completed. Through the serial communication interface 9 and the wireless receiving module 10, the collection of wireless communication data, system data packaging processing, level conversion reporting and return, data processing to drive LCD and control 3 relays according to temperature values, and control by 3 relays 3-way indicator light installed on the front panel of the switch cabinet. Under the condition that does not affect the normal operation, new alarm data can be input online, and the new data will take effect after the confirmation key is pressed.
 This monitoring system is compatible with multiple operating systems, and can monitor the temperature rise of the contacts of the high-voltage switchgear in real time in high voltage, high temperature and strong magnetic fields, and complete the collection, storage, query and report output of the data of each aggregation node. Conveniently support the secondary development of users.