| In the face of the increasing environmental degradation and energy shortage,China has actively carried out energy-saving and emission reduction work,optimized the energy supply structure,and deepened the construction of a new energy system.Due to the high randomness and volatility of renewable energy,large-scale grid connection of new energy generation will bring risks to the power grid system.Through microgrid systems,efficient utilization and on-site consumption of renewable energy can be achieved.Switched Reluctance Generator(SRG)has the advantages of simple and reliable structure,wide speed range,and is suitable for wind power generation and other working environments.This thesis focuses on the SRG wind power generation system in a DC microgrid and studies three power/signal synchronous transmission strategies.Firstly,this thesis elaborates on the working principle of the SRG system,establishes a mathematical model of the SRG,and derives expressions for the phase current and commutation ripple of the motor,and analyzes three basic control methods and their compatibility with power/signal synchronous transmission strategies.Secondly,a power/signal composite modulation strategy based on time-division multiplexing is proposed to achieve synchronous transmission of multiple signals.This method modulates the signal at different stages of output voltage ripple,uses commutation ripple characteristics instead of synchronous codes in time-division multiplexing frame structure to improve the signal transmission efficiency and avoid false synchronization.At the signal receiving end,the demodulation method of fast Fourier analysis is used to realize the signal demodulation,and the feasibility of the proposed signal modulation method is verified.Then,based on the frequency division multiplexing transmission strategy,two power/signal composite modulation strategies for SRG are proposed.By utilizing the overlapping characteristics of the motor winding during the power generation stage and modulating the output currents of different windings at the same time,two sets of voltage ripple with different frequency characteristics are injected into the power line.A coupled resonant circuit is designed and combined with the SRG power/signal composite modulation strategy to achieve parallel transmission of signals.The signal ripples and spectrum of the two methods are analyzed and compared to provide reference for the parameter optimization of power/signal synchronous transmission strategies.Finally,in order to improve the concealment and anti-interference of signal transmission,a power/signal synchronous transmission strategy for SRG based on frequency hopping spread spectrum is proposed.The carrier frequency is modulated based on the frequency hopping spread spectrum sequence,and the pulse duty cycle is modulated based on the output current state to suppress the commutation ripple component in the output voltage.The fast Fourier operation results are processed according to the frequency hopping sequence of the ripple frequency to achieve the demodulation of the frequency hopping signal.There are 72 figures,5 tables and 86 references in this thesis. |
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