Abstract:This article proposes a wireless temperature monitoring system for power equipment from the perspective of power safety production. The key technologies for system implementation are studied in detail, and the hardware equipment composition and application software design of the system are introduced.

KeywordsPower equipment; Temperature monitoring; wireless communication

1. Introduction

There are a large number of electrical connection points in various links of the power system, including generation, transmission, distribution, and use. These connection points have varying degrees of contact resistance due to various reasons. The contact resistance directly causes the temperature at the contact point to rise, and during operation, these connection points further increase the contact resistance due to mechanical vibration, overheating oxidation, expansion relaxation, surface corrosion, and other reasons. This leads to local melting of the metal at the connection point, generating sparks or even arc discharges, affecting the surrounding insulation materials, causing electrical equipment damage, power outages, fires or explosions, and threatening the economic and operational safety of the power grid. During the production process, accidents caused by overheating of electrical equipment contacts account for a large proportion of overall electrical accidents. If not detected in a timely manner, it will not only consume electrical energy in vain and increase line losses, but more importantly, it will become a hidden danger of accidents and pose a threat to safe power supply. Based on the above objectives, this article proposes a real-time, online temperature monitoring and warning solution based on wireless sensor network communication technology.

2. System composition

This system consists of wireless temperature sensors, data repeaters, data concentrators (communication repeaters), temperature displays, and backend monitoring and analysis software. The system composition is shown in Figure 1. The system adopts a hierarchical distributed structure both physically and functionally to ensure flexibility in system configuration and convenience in functional configuration. The wireless temperature sensor, data repeater, data concentrator, and temperature display are all equipped with a 16 bit ID, which does not require any configuration and can be installed and used immediately. The number of sensors, repeaters, concentrators, and displays can be configured as needed without any scale limitations, as long as there are no duplicate IDs within the wireless communication distance. Therefore, it can adapt to the needs of temperature monitoring and early warning projects of various scales; Wireless communication has communication anomaly alarm and self recovery functions.

Figure 1 Structure diagram of temperature monitoring and early warning system for power equipment

3. Hardware Design

Wireless temperature sensors have adaptive capabilities such as automatic RF power adjustment, network routing discovery and maintenance, and network routing (relay) selection, which can reduce power consumption and extend battery life. Utilizing the universal ISM and SRD unlicensed frequency bands for RF communication, and adopting the simplified ZigBee wireless sensor network communication protocol to transmit temperature and working status information, the communication is stable, efficient, and consumes less power. The temperature display instrument is used to display the temperature values collected by the data repeater and data concentrator at each temperature measurement point, the working status of each sensor, and generate alarm information.

4. Backend management software functionality

The monitoring computer can exchange data with several communication concentrators and configure the working parameters of the entire station or temperature sensors, data repeaters, data concentrators, and temperature display instruments.

Figure 2 User interface of temperature monitoring and warning system for power equipment

The engineering instance screen of the management software is shown in Figure 2. The management software provides various common electrical equipment symbols (supporting user expansion) to design or modify display screens, alarm settings, and reports according to on-site needs. It can also embed on-site geographic distribution maps, images of transformers, circuit breakers, and isolating switches, and use these images as backgrounds to place text boxes, thermometers, and other symbols, intuitively displaying the temperature of equipment joints. By setting alarm limits for each temperature measurement point, an alarm can be generated when the temperature exceeds the set value, the temperature rises rapidly and its rate of change is higher than the set value, or the three-phase temperature imbalance exceeds the threshold. The temperature values of each busbar joint, cable joint, and switch contact are saved in a historical database according to the set method, and can be queried by combining temperature measurement points, electrical intervals, monitoring periods, alarm records, and other conditions. The results are automatically generated into a report, which can be adjusted according to user needs, including columns and styles, and supports dynamic data connection functions. In order to facilitate different personnel in relevant positions to timely understand information, the management software embeds a WEB server and designs SSL based authorization access. Computers in local area networks (such as scheduling data private networks) can implement monitoring host functions on local network browsers.

5. Introduction to Ankerui Wireless Temperature Measurement Products

5.1 Temperature Sensor

a. Battery powered wireless temperature sensor

A sensor installed in the heating area to collect temperature data and transmit it wirelessly.

There are currently three types of wireless temperature sensors:

b. CT induction power wireless temperature sensor

Sensors installed at high current locations such as circuit breaker contacts, busbars, and cable junctions to collect temperature readings and transmit them wirelessly.

There are currently two types of wireless temperature sensors:

5.2 Reception/Display Unit

a. Receiving unit

b. Display unit

6. Conclusion

The results show that the temperature monitoring and early warning system based on wireless network technology can accurately report the temperature rise of the heating components of the tested high-voltage equipment, eliminate the blind spots of traditional temperature, timely eliminate hidden dangers, reduce accidents, and minimize economic losses. It has important practical significance for improving the reliability and safety of power grid operation.