Research Of Compressed Sensing Channel Estimation And Wavelet Signal Detection Method

With the grid intelligent level getting higher and higher, more and more electric energy data acquire terminal equipped with communication function has been used in the power grid. That lead to a growing demands for low-voltage power line carrier communication, and a large number production of harmonics which bring about more difficulties in the electric parameters detection. Regarding the requirement of electric energy data acquire terminal equipped with communication function, and substantial increase of the transmission rate because of OFDM technology applied to the LV-PLC, OFDM low-voltage power line carrier communication channel estimation problem has become a new challenge in the process of the smart grid development. For the electric parameters detection, some wavelet signal detection method has been proposed, but there are still some problems that need to be further solved.Firstly, this paper introduces the production, research status, basic principles and algorithm implementation of compressed sensing and wavelet transform theory, discusses the research status and development trends of OFDM channel estimation and electric parameters detection.Secondly, this paper deeply studies the basic principles of OFDM, gives the block diagram of OFDM system, establishes the OFDM baseband transmission system, and deduces the mathematical model of OFDM pilot signal transmission. The mathematical model presents the relationship between sender pilot signal and receiver pilot signal, which provides the premise condition for applying compressed sensing to the OFDM low-voltage power line carrier communication channel estimation.Thirdly, specific to the LV-PLC multipath channel, this paper analyzes the carrier signal transmission process in LV-PLC multipath channel, and establishes the multipath channel transmission characteristics model of the LV-PLC. Based on the multipath channel transmission characteristics model and the model parameters, this paper proves the amplitude-frequency characteristic curve and impulse response of multipath channel through experiments.Then, this paper studies the LS and MMSE channel estimation methods and interpolation method based on DFT, proves that the mathematical model of OFDM pilot signal transmission is satisfied with the CS conditions, converts multipath channel estimation problem to CS signal reconstruction problem, and first proposes the OFDM LV-PLC compressed sensing channel estimation method. The experimental results show that:OFDM LV-PLC compressed sensing channel estimation method had better performance than LS and MMSE channel estimation method.Finally, this paper studies the wavelet sub-band decomposition method, gives the electrical parameters wavelet representation method, analyzes and deduces the structure of IIR multiphase structure wavelet signal detection filter bank, first proposes the IIR multiphase structure wavelet signal fast detection method. The experimental results show that:IIR multiphase structure wavelet signal fast detection method had obvious advantages in computational efficiency, meanwhile this method was suitable for electric parameters detection situation of complex harmonic and high real-time requirements.