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As the long‐term consequences of coronavirus disease 2019 (COVID‐19) have not been defined, it is necessary to explore persistent symptoms, long‐term respiratory impairment, and impact on quality of life over time in COVID‐19 survivors. In this prospective cohort study, convalescent individuals diagnosed with COVID‐19 were followed‐up 2 and 3 years after discharge from hospital. Participants completed an in‐person interview to assess persistent symptoms and underwent blood tests, pulmonary function tests, chest high‐resolution computed tomography, and the 6‐min walking test. There were 762 patients at the 2‐year follow‐up and 613 patients at the 3‐year follow‐up. The mean age was 60 years and 415 (54.5%) were men. At 3 years, 39.80% of the participants had at least one symptom; most frequently, fatigue, difficulty sleeping, joint pain, shortness of breath, muscle aches, and cough. The participants experienced different degrees of pulmonary function impairment, with decreased carbon monoxide diffusion capacity being the main feature; results remained relatively stable over the 2–3 years. Multiple logistic regression analysis demonstrated that female sex and smoking were independently associated with impaired diffusion capacity. A subgroup analysis based on disease severity was performed, indicating that there was no difference in other parameters of lung function except forced vital capacity at 3‐year follow‐up. Persistent radiographic abnormalities, most commonly fibrotic‐like changes, were observed at both timepoints. At 3 years, patients had a significantly improved Mental Component Score compared with that at 2 years, with a lower percentage with anxiety. Our study indicated that symptoms and pulmonary abnormalities persisted in COVID‐19 survivors at 3 years. Further studies are warranted to explore the long‐term effects of COVID‐19 and develop appropriate rehabilitation strategies. [ABSTRACT FROM AUTHOR]

Under unbalanced grid voltages, the output active power, reactive power, and current in the stator of a doubly fed induction generator (DFIG) exhibit harmonic frequency fluctuations and distortion. Conventional control strategies to eliminate these effects only focus on one control objective at a time. This paper proposes a genetic algorithm‐based multi‐objective coordinated control strategy to eliminate multiple undesired effects in DFIGs under unbalanced power supply conditions. In order to enhance its low‐voltage ride‐through (LVRT) capability and effectively reduce the impact of the grid current on the power grid, this strategy first introduces adjustment coefficients when calculating the directive current of the rotor, and constructs a unified analytic expression for multiple control objectives. Next, the multi‐objective optimization model is constructed using the minimization of the fluctuations in active and reactive powers as the control objective and the total harmonic distortion (THD) of the stator current as the constraint condition. Finally, the adjustment coefficients are optimized using the multi‐objective genetic algorithm. From the perspective of the overall requirements of generators under a voltage unbalance fault condition, the optimized adjustment coefficients aim to limit the THD of the stator current within an acceptable safety range while simultaneously minimizing the fluctuations in the active and reactive powers. The effectiveness and feasibility of the proposed control strategy are proven by both simulation and experimental results. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]