Wireless Channel Measurement And Characteristics Analysis In Substation Scenarios

With the rapid development of information technology,the Internet of Things technology arises at the historic moment.It is an important trend of today’s and future science and technology development to realize the intelligent construction of internet of everything and man-machine intercommunication.As the key technology of information construction,wireless communication provides a solution for the construction of the Internet of Things.Ubiquitous power Internet of Things is a part of the application of Internet of Things in power scenarios.It connects all links of the power system and realizes an intelligent system with comprehensive state perception through wireless communication technology.As the core of the power system,the wireless network coverage of the substation is indispensable.Different from ordinary scenes,there are a large number of metal electrical equipment in this scene,which will have a great impact on the radio wave propagation and reduce the reliability of the wireless communication system.In order to meet the ubiquitous demand of power Internet of Things,channel measurement is carried out in the typical electrical scene of substation to explore the difference of channel parameters between the existing standardization and the actual environment,master the channel parameters,build a reasonable channel model,and promote the construction of smart substation wireless network.This thesis completes the construction of wireless channel measurement system,using the frequency domain channel measurement method to obtain the channel impulse response,by eliminating the system response to obtain more consistent with the real space channel data,and in the laboratory simulation and measured verification.The wireless channel measurement system built in this thesis includes two application modes.One is to use the single antenna measurement system to measure the channel characteristic parameters in the time delay domain and power domain.Secondly,multi-antenna(based on phased array)measurement system is used to measure the channel characteristic parameters in the angle domain,and an angle measurement method based on phased array channel measurement is proposed.By taking advantage of the narrow beam of phased array antenna,the directional Power Angular Delay Profile is obtained through beam scanning.A specific algorithm is used to extract the effective multipath,and the departure angle,arrival angle,delay and power of multipath are obtained,which provides a reference for the research of spatial characteristics of wireless channels.At the same time,according to different scenes and different frequency points of the substation,the measuring system is used to carry out the channel measurement work for the 110 k V indoor substation and 220 k V outdoor substation.Based on the actual measured data,the logarithmic distance shadow fading model of line-of-sight(LOS)and non-line-of-sight(NLOS)scenes in multi-area substation is obtained.By comparing the changes of multipath number and root-mean-square delay spread,the outdoor substation has more complex propagation environment and more obvious channel fading characteristics than the indoor substation with smaller scale.By analyzing the distribution of angular power spectrum in typical regions,it is found that the angular power spectrum in NLOS scenario is more dispersive,multipath is more abundant and angular spread is larger than that in the scene with LOS direct radiation.The above research provides a theoretical reference for the wireless channel research and network coverage of substation scene.