Performance Analysis And Research Of Wireless Sensors In Discharge Environment

EHV and UHV transmission is a key link in power grid construction.The traditional method to monitoring transmission lines is manual inspection.But it is slow and inefficiency,and due to worker’s status,not all the possible problems can be discovered immediately,and sometimes may even report wrong or error information.So,using WSN for automatic monitoring is a trend,and it is under construction or already in service in some places.However,due to the special environment around the high voltage transmission lines,the performance of wireless sensor cannot be compared with that working in normal places.Some sensors are even not working or totally damaged.Especially,the sudden change of the electric field caused by discharge of the transmission line,which brings much higher intensity than usual,could have a stronger impact on sensors.This graduation thesis is based on a project of State Grid,the research on intelligent information diagnosis technology for UHV large span transmission tower health monitoring system,and mainly does researches as follows:First,we analyze the discharge environment of EHV and UHV transmission line.EHV and UHV towers contain high voltage and most of them are not easy to access.The general impact mode of transmission lines is manifested in two forms: electric field interference and magnetic field interference.Since electric field interference is the main mode of influence in the close range,so we analyze it around transmission lines.Finite element method is used to analyze and solve the surrounding electric field of corona discharging transmission line and tip discharging and grasp the regular pattern of the distribution.Secondly,an analysis is made to the WSN.We combine radiation field interference and wireless sensor module and make a research on the main type of interference.The antenna part of the wireless sensor is affected by the electric field to generate an interference current,and the circuit itself is affected by the vary magnetic field to generate an induced voltage.Overall,the closed-loop coupling creates interference that causes the sensor to be malfunctional,and the electric and magnetic fields affect different parts of the sensor,respectively.Last,the experimental platform was set up to test the working condition and communication situation of the wireless sensor in the discharging environment.The results of the corona continuous discharging test show that the electric field strength has a large influence on the sensor itself,which directly leads to an increase in the bit error rate,and the main reason for the loss of packet loss rate is the distance between the sensors.Then the Marx generator is used to simulate the tip discharge.The experimental results show that the tip discharge has a limited effect on the sensor within a certain range,but once the limit is broken,the sensor could be directly damaged,and the impact is irreversible.