Research And Implementation Of Key Technologies In OFDM-based Power Line Communication System

Power Line Communication(PLC)is not a new concept.With the continuous development and evolution of the smart grid,the PLC technology faces new opportunities and challenges.Traditional narrowband PLC technology provided very limited capabilities on data transmission,and could not meet the needs of developing the smart grid.It is imminent to apply a new generation PLC technology with higher transmission capacity.In order to combat the strong noise,interference and severe frequency selective fading of the power transmission lines,some new generation of narrowband PLC systems,such as PRIME and G3-PLC from European,tend to adopt an Orthogonal Frequency Division Multiplexing(OFDM)technology that is of high flexibility and anti-multipath fading capability.At present,the standardizaiton of a new generation national standards on narrowband PLC of China is on the way,it takes the G3-PLC standard as an important reference.Fully grasping of the core technology of G3-PLC will be very helpful to meet the rapid implementation and deployment of national standard equipments of the new generation narrowband PLC in the future.In this thesis,we focus on the design and implementation of OFDM-based G3-PLC system.On the foundation of analyzing the G3-PLC standard in detail,the simulation model of the communication system is built.The implementation and debugging on the self-designed DSP hardware platform are completed,and these are prepared for the next Application Specific Integrated Circuit(ASIC)conversion.Firstly,we make a brief review of the history of the PLC development and present situation.Then we compare the current widespread mainstream PLC standards,and give the similarities and differences of important technical indicators between similar ones.Secondly,we introduce the OFDM-based G3-PLC standard.The Physical Layer(PHY)specification is described especially,and the overall structure of the OFDM-based PLC system is given.On the basis of a description of the OFDM technology technology,the key technologies of the system are discussed.Thirdly,based on the PHY specification of the G3-PLC standard,the simulation model of the whole system is built on MATLAB Simulink platform.The system model adopts modular circuit construction oriented hardware implementation.The details of the structure of each module and the configuration of their parameters are given.To verify the correctness and effectiveness of the designed algorithm,the simulations of the system model are performed with different parameters.The simulation results provide theoretical support for the next hardware implementation.Finally,the OFDM-based PLC system is implemented on the slef-designed DSP hardware platform.The adopted hardware platform and core chips are introduced,and the top-level scheme of the system and designed Interrupt Service Routines(ISRs)are explained.In order to facilitate the interaction between the chips,a private data register for MCU and front-end chip are developed respectively.This design makes an effective interaction between DSP and MCU,as well as the DSP and front-end chip.Due to the limited memory of the DSP chip,according to the usage and design condition,an appropriate memory mapping scheme is shown,and this practice optimizes the data access processing.Based on the single-thread property of DSP,the processing flow of the designed transmitter and receiver are described.The function and characteristics of each module in the system are specified,especially to the implementation of the correlationwaveform detecting algorithm based on the correlation characteristics of the preamble.At last,a typical test scenario and test performance are given,which verify the validity and reliability of the designed system.