Switched Reluctance Wind Power Generation System Based On Variable Generation Voltage Converter

Wind energy is a clean, efficient and renewable energy resource, and it is developed and used widely all over the world. On the one hand, developing wind power generation is beneficial to adjust the power structure; on the other hand, developing wind power generation can help reduce environmental pollution and promote social process. Switched Reluctance Generator (Switched Reluctance Generator, SRG for short) has a number of advantages, including simple and robust structure, more controllable parameters, high torque-to-inertia ratio, wide speed-regulating range, high power density and so on. Hence it has broad application prospects in the wind power generation system.The conventional asymmetric bridge converter is commonly used as power converter of SRG driver. When the wind speed is low, the wind turbine rotational speed is also low, then SRG corresponds to the optimum rotational speed is lower than the rated speed, thus the back-EMF of the SRG may be lower than the generation voltage. As a result, the phase current will not increase at the generation stage, moreover, the machine utilization coefficient and conversion efficiency of the system are reduced. Therefore, avoiding the phase current decreasing is one of the goals must be concerned in the switched reluctance wind power generation system when a SRG is operating at medium and low speed.In order to overcome the above disadvantages, this paper presents a variable generation voltage converter topology which can control the generation voltage independently. When the SRG is operating at different speeds, it can get different generation voltages which are less than the back-EMF at the generation stage, avoiding the phase current decreasing. Besides, it can regulate the generation voltage completely decoupled from the excitation voltage through controlling the switching device turned on or turned off in the Buck-boost cuicuit of the variable generation voltage converter. In addition, compared with the asymmetric bridge converter, each phase of the variable generation volatage converter reduces one switch and one diode since continuous current operating mode is not required. The proposed converter reduces the system cost and switching losses.The model of a three phase 12/8 SRG wind power generation system is built and simulated using MATLAB/SIMULINK simulation software. The simulation results show the switched reluctance wind power generation system based on variable generation voltage converter can improve the phase current waveform efficiently, increase conversion efficiency of the system and also verify the validity and feasibility of the proposed converter.