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Action research is a preferred research method among primary and secondary school teachers. However, due to the lack of in-depth understanding of action research, teachers have encountered various challenges in the actual research process. Establishing a structural model for developing action research capabilities can help frontline teachers accurately grasp the essence of action research and truly understand what it is and how to conduct it. Based on research and analysis of relevant literature, combined with teaching practice, a "stepped-multifaceted" ability structure model has been extracted, with core competency elements such as "problem awareness, communication and collaboration skills, research skills, analytical and summarization skills, and reflection and improvement skills". This model visualizes the action research ability of primary and secondary school teachers. Based on this model, the following pathways have been proposed to enhance teachers' action research capabilities and promote their professional development: creating a community that encourages teacher communication and collaboration skills, using the concept of "community" to enhance their participation abilities; using research projects to drive teachers' development of research skills by allowing them to learn through practical experience; encouraging teachers to engage in continuous reflection throughout the entire research process, thereby stimulating their problem awareness and research consciousness; emphasizing the importance of lifelong learning and improving one's abilities through the cyclical process of "learning-action".

Low-frequency transmission system (LFTS) based on modular multilevel matrix converter (M3C) has great application potential in offshore wind power transmission,urban power grid and long-distance power transmission. In order to study the startup process and the control strategies of LFTS and connect the converter station to the low-frequency transmission line without voltage or current impulse of M3C,a startup method of undisturbed grid connection is proposed. Firstly,the structure and operating principle of the LFTS are analyzed. Then,the selection principle of sub modules and the charging process of M3C are analyzed with two-terminal LFTS as the target. Taking the advantage that the blocked M3C does not exchange power with the low-frequency power grid when the capacitor is at rated voltage,the problems of over-voltage and over-current that tend to occur during LFTS startup can be solved by flexible control of M3C and reasonable design of startup strategy,without additional control devices and detecting the synchronization of the breaker. Finally,a real time digital simulation system (RTDS) is built to verify the proposed startup method. The simulation results show that converter stations connect to the low-frequency transmission line without voltage or current impulse. Also,the proposed strategy is correct and has a great prospect of the engineering application.