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In order to effectively compensate negative sequence current (NSC) of the V/v traction system and reduce the capacity and cost of railway power conditioner (RPC), a low-cost hybrid railway power conditioner (HRPC) technology scheme considering regenerative braking energy is proposed in this paper. The proposed HRPC consists of an RPC with a modular multilevel converter structure (MMC-RPC) and a railway static var compensator (RSVC). First, the circuit topology of the proposed scheme and the principle of NSC compensation considering regenerative braking energy are given. Then, the capacity configurations of MMC-RPC and RSVC are presented to reduce the capacity of active equipment and further lower the investment cost of HRPC. On this basis, the HRPC with energy storage units (ESU-HRPC) is studied to recycle the remaining regenerative braking energy, and the difference from the proposed HRPC is further analyzed. Subsequently, the capacities of HRPC and ESU-HRPC are designed based on the measured power data from a heavy-haul railway in China as an example. Besides, the system control strategy is given. Finally, the proposed technical schemes are verified by the hardware in loop (HIL) experiments. [ABSTRACT FROM AUTHOR]

Introduction: Orthodontic treatment and adenotonsillectomy (AT) are both conventional treatments for paediatric obstructive sleep apnoea (OSA). Each approach has distinct treatment advantages; however, there is currently a lack of solid evidence to support their efficacy comparison. We hypothesise that the objective effect of orthodontic treatment is not inferior to AT in children with moderate OSA and mandibular retrognathia, but orthodontic treatment has the advantage of promoting dentofacial growth., Methods and Analysis: This is a randomised, open-label, parallel-group, active controlled trial that will study the efficacy of orthodontic treatment versus AT in children with moderate OSA accompanied by tonsillar adenoid hypertrophy and mandibular retrognathia. A total of 98 patients will be enrolled and randomised in a 2:1 ratio to either orthodontic treatment or AT group. Participants will be recruited at Shanghai Stomatological Hospital, Shanghai Children's Hospital of Shanghai Jiaotong University and Children's Hospital of Fudan University, which are all located in Shanghai, China. The primary endpoint is the per cent change in the obstructive apnoea-hypopnoea index from baseline (month 0) to the primary endpoint (month 7), and the mean reduction in A point, nasion and B point angle on cephalometric measurements by lateral X-ray films. Important secondary efficacy endpoints include sleep duration with oxygen saturation below 90% according to polysomnography and subjective symptoms (assessed by the OSA-20 questionnaire), etc. Safety endpoints will also be evaluated., Ethics and Dissemination: The study was approved by the ethics committees of Shanghai Stomatological Hospital (approval no. (2021)002), Shanghai Children's Hospital of Shanghai Jiaotong University (approval no. 2021R046-F01) and Children's Hospital of Fudan University (approval no. (2021)136). Before enrolment, a qualified clinical research assistant will obtain written informed consent from both the participants and their guardians after full explanation of this study. The results will be presented at national or international conferences and published in peer-reviewed journals., Trial Registration Number: ChiCTR2000037288., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)