Abstract. Guangzhou, one of China's megacities, is beset with frequent occurrence of high-concentration ozone events. In this study, online instruments were used to simultaneously monitor ozone, nitrogen oxides (NO x ) and volatile organic compounds (VOCs) at GPACS (the Guangzhou Panyu Atmospheric Composition Station) of the China Meteorological Administration, from June 2011 to May 2012, in order to determine their characteristics, the effect of VOCs on ozone photochemical production and the relationship between VOC / NO x ratio and ozone formation. The results showed that during the observation period, the seasonal variation of ozone concentration was lower in spring and winter compared to summer and autumn, which is opposite that for VOCs and NO x . In terms of VOCs, aromatics had the largest ozone formation potential, among which toluene, xylenes, ethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene were the most important species, with a total contribution of about 44 %. As the VOC / NO x ratios were very high during high-concentration ozone events that occur all year round, we speculate ozone production was likely to be NO x -limited regime (12:00-16:00 LT) in Guangzhou. Further investigation based on numerical models is needed in the future to obtain more detailed and robust conclusions.

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This paper investigates the modeling, simulation and implementation of a wind power system based on a Permanent Magnet Synchronous Generator (PMSG). A comprehensive portfolio of control schemes are discussed and verified by Matlab/Simulink simulations, in the context of grid integration and Maximum Power Point Tracking (MPPT) operations. Particularly, to investigate the Fault-Ride-Through (FRT) and robustness capabilities, various wind speed scenarios and a line voltage droop are introduced to the wind power system to investigate its dynamic performance. A reference power curve, i.e., power versus generator speed, is employed in the turbine model to implement the MPPT. In addition, a position/speed sensorless operation approach based on Sliding Mode Observer (SMO) is implemented to reduce system cost and improve control reliability. Simulation and experimental results demonstrate the robust control of the power and speed in the PMSG wind power systems.

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