| The accidents happened during power transmission are mostly due to the over-range of joints temperature caused by the increase of contact resistance. As a result, long term of power cut was inevitable, and a fortune was cost. Thus, as a weak point of power transmission, the temperature monitoring of transmission line joints becomes significant. this dissertation described a new joints temperature measuring system that can obtain both temperatures of transmission lines and transmission line joints, get the absolute temperature difference between them, complete data communication between gateway and child nodes, and with the assistance of GPRS/GSM mechanism, realize the transmission line joints temperature measurement of multiple nodes under low costs.The frontal two chapters include contents of significations and current methods of the transmission line joints temperature online monitoring, as well as the scheme selection of our implementation approach. Chapter one introduces the significations and current methods of the transmission line joints temperature online monitoring. Through the analysis and comparison of current approaches, there presents the advantages and necessities of the novel device design and development described in the later parts of the dissertation. Chapter two makes the selection of ZigBee technology constructed upon IEEE 802.15.4 standard, through a comparison and contrast among popular wireless technologies.Chapter three of this dissertation introduces the hardware design of the device based on the required parameters of the system scheme. First, starting with the whole body structure arrangement, the beginning segment elaborates the important parts of MCU control, power supply, data acquisition and GPRS transmission. Next, the dissertation especially expounds the ZigBee platform to accomplish the wireless sensor networks, including the network topology design and hardware selection. Finally, in the last part presents the hardware interfaces and connections, PCB design of selected MCU and RF chip.As to the implementation of the wireless sensor networks function mostly rely on the controlling software embedded in the designed hardware, the following section of this dissertation described the most important and difficult: the embedded software implementation and debugging. Chapter four completes the ZigBee stack components and application end device implementation after a brief analysis of the stack structure. Chapter five gives details of the network formation algorithm and data communication mechanism. These contents ensure the accomplishment of a wireless sensor network that can function as an ad-hoc network.Considering the installation position of the device should be on the high-voltage transmission tower, where the electromagnetic and climate environment is harsh, a simulation test is arranged with a manual up-flow equipment to make sure the system stability, especially the wireless communication stability. The test result shows that the transmission line joints temperature online monitoring device can maintain a stable operation. The last but not least important chapter summarizes the system development experience, and makes an expectation for the system improvement.After all, not only have the new system implemented the functions as a joints temperature online monitor, but also realized a brand new monitor combining the character of flexibility with utility, and made a big progress on the way to large-scale monitoring of the grid network. |
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