| Smart power grid is the intelligence of power grid system.It has the characteristics of wide application scenarios,various services and high transmission stability.It is the development trend of power system in the world at present.Power Line communication(PLC)is the main communication technology of smart grid because of its wide coverage and simple wiring.However,because of its channel characteristics,power line communication has strong channel attenuation and impulse noise.Wireless communication has also become one of the communication technologies of smart power grid due to its flexible wiring and good scalability.However,due to the complex network topology of smart power grid,a wide variety of access electrical equipment,and high transmission reliability requirements,only one communication technology cannot meet the transmission requirements of smart grid.Therefore,the hybrid power line and wireless heterogeneous network can give full play to the advantages of the two communication modes,which is an important means to improve the transmission efficiency and reliability of smart grid and is also the development direction of smart grid.So,the research significance of this thesis is to realize the hybrid power line and wireless channels and improve the diversity gain of dual-mode communication system.Based on the hybrid power line and wireless dual-mode,this thesis mainly analyzes and researches the models of power line and wireless dual-mode system,the technology of multi-channel diversity combination,and impulse noise suppression technology.The research content of this thesis is summarized as follows:1.The characteristics of power line and wireless channel are analyzed,and the power line channel model and noise model are studied and simulated,and the wireless channel model and noise model are analyzed and studied.2.Based on the physical layer protocol of low-voltage power line broadband carrier communication,the single-mode physical layer system based on OFDM modulation technology is introduced.On the basis of single-mode physical layer,three dual-mode modes are extended and corresponding system models are established.The three dualmode modes are divided by the positional relationship of merging and OFDM demodulation.The first dual-mode is merging before OFDM demodulation,the second dual-mode is merging after FFT,and the third dual-mode is merging after solving constellation mapping.The dual-mode system adopts the same data frame structure,encoding mode and OFDM modulation system as the single-mode system.3.Aiming at the problem of dual-mode merging,three common diversity merging algorithms in wireless systems are introduced.Then,the proposed dual-mode merging algorithm is combined with diversity merging algorithm.In dual-mode one,three merging algorithms are combined respectively,in dual-mode two,equal gain merging and maximum ratio merging are combined respectively,and in dual-mode three,equal gain merging is combined,and their performance is simulated by Matlab in different scenarios.The simulation results show that the performance of each dual-mode combination scheme is better than that of the single-mode system,among them,the performance of combined scheme two is better than the other two schemes.4.Aiming at the problem of impulse noise in dual-mode system,the traditional nonlinear noise suppression algorithm and compressive sensing algorithm theory are studied and analyzed firstly,and finally the impulse noise suppression algorithm based on compressive sensing and adaptive threshold is proposed.The proposed algorithm can effectively suppress impulse noise.And by comparing the performance of the single mode system,the noise suppression ability of the algorithm is verified. |
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