Research On Key Technology Of Low-voltage Power Trunk Carrier Communication

The use of wireless communication in explosion-proof electrical environments will bring some hidden dangers,so power line carrier communication is the most ideal communication method.The power carrier communication technology based on the low-voltage power network can effectively network the explosion-proof electrical equipment of various manufacturers,which is the basis for the management,monitoring and safety prevention of various explosion-proof electrical equipment through the power carrier communication system platform.Power line channel characteristics include noise characteristics,impedance characteristics,and attenuation characteristics.The combination of the three is a prerequisite for reliable communication in low-voltage power lines.The long distance(more than several hundred meters)from the distribution transformer to the low-voltage main line of the workshop will cause signal attenuation,and the use of some high-power equipment in the workshop will cause serious noise interference.These problems are the difficulties in establishing carrier communication,and they are also the focus of this article.The thesis mainly completed the following:Firstly,the measurement methods of the noise characteristics,attenuation characteristics and impedance characteristics of the power line channel are designed.This paper uses the combination of electromagnetic field simulation tools and actual measurements to accurately obtain the unit length parameters of the four-core power line,establishes a four-core cable model of the low-voltage trunk line,and verifies the model by actual measurement.Secondly,the channel characteristics of low-voltage power lines are measured and analyzed in the laboratory environment and industrial environment.The results show that the use of frequencies above 500 k Hz as the communication band can take into account the effects of noise,impedance,and attenuation.Based on this conclusion,this paper designs a carrier communication prototype using multiple technologies such as multi-carrier and mixing,and conducts field tests.On-site communication test results prove that the prototype has a good communication effect and can achieve a communication rate of more than 20 kbps.Finally,the short-time Fourier transform and cyclic spectrum analysis methods are used to analyze the noise characteristics of the channel.According to the correlation and periodicity of the noise,the adaptive filtering method is used to deal with the noise,and good filtering is achieved effect.