As a high-standard verdant method of transportation, electric-powered-vehicles have become the development hotspot of the automotive business in recent years. Large scale access to electric-powered vehicles can form a distributed energy storage system, which can improve the operational performance of power grid peak shaving and frequency modulation, and improve the comprehensive utilization efficiency of system energy. But at the same time, large-scale electric-powered vehicles connected to the DC distribution network will have a certain impact on its topology. Therefore, this paper studies the impact of the access location and number of electric-powered vehicles on the network topology and establishes a multi-dimensional evaluation system of the DC distribution network topology. The application of this result can play an evaluation and guidance role in the operation stability of the DC distribution network in the case of large-scale access to electric-powered vehicles.

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Visibility is closely related to air quality and is therefore a source of concern. Using data from the National Basic Weather Station (NBWS), this study measured visibility variation in Zhengzhou from 2008 to 2017. The effects of PM2.5 and meteorological parameters on visibility were also assessed. Results indicated that the mean annual visibility fluctuated between 8.07 km and 14.02 km, decreasing during the period from 2008 to 2013 and then increasing slightly after 2013. The seasonal mean visibility was 11.69 km in spring (the highest value), 11.37 km in summer, 9.42 km in autumn, and 8.98 km in winter (the lowest value). The mean annual concentrations of PM2.5 from 2015 to 2017 were 90.83 μg m-3, 79.89 μg m-3, and 66.69 μg m-3, respectively. These were 159.51%, 128.26%, and 90.54% higher than 35 μg m-3 of the second grade of China National Ambient Air Quality Standards (CNAAQS). Additionally, direct radiation, total radiation, temperature, and relative humidity were positively correlated with visibility, whereas PM2.5 mass concentration, scattered radiation, and wind velocity were negatively correlated with visibility. Further research is needed to analyse the effect of PM2.5 on visibility and the mechanism through which this occurs.

This paper studies the silicone rubber insulation coating material used for the modification of overhead bare wires. The influence of two reinforcing fillers of silicone rubber on the density, mechanical properties and electrical properties of insulating coating materials was explored. Finally,25 copies of white carbon black were selected as a reinforcing filler to prepare a low-density, high-strength, and good insulating silicone insulating coating material.