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The ReaxFF molecular dynamics simulation and Monte Carlo method were adopted to analyze the pyrolysis process of cellulose in insulating papers from the perspective of microscopic atom. Molecular dynamics failed to continuously describe the motion behavior of an atom. According to this principle, the system can only calculate the atomic state on the node and then move the atom by a time step to continue calculating the atom. This paper would put forward the optimal step setting method of cellulose thermal decomposition in insulating paper: setting one step every other 0.1 fs. Specifically, for small molecules with a simple structure, such as H 2 O, the step size was set to 0.4 fs or less, while the step size of macromolecules with complex structures (CH 2 O 2) should be set to 0.2 fs or less. In addition, the relationship between the step size and the temperature to which the system was heated was given as well in this paper. In previous literatures, empirical values were used to set the step size. This study would not only provide a theoretical basis for the study on the bond formation and fracture process of cellulose pyrolysis products, but also offer the data and guidance for related fields in the future, thus rendering an efficient simulation process. INDEX TERMS Molecular dynamics, step size, cellulose, pyrolysis.

This paper presents the dynamic simulation and testing to verify the smart substation solutions designed for a brown field 110 kV retrofitting project. An IEC 61850 based aotomation design, transitioning the conventional substation into a smart substation, where existing current/voltage transformers remain in service, and smart Field Apparatus Interface Units (FAIUs) are utilised to bridge the conventional primary system to the IEC 61850 based secondary system. While outdoor switchgears and field instrument transformers are equipped with FAIUs, MV indoor switchgears are installed with IEDs mounted on the top. Direct point-to-point connections serve as process buses, and a single PRP/RSTP LAN is employed at station bus level. Extensive dynamic simulation and testing were conducted in the Smart Substation Technologies Lab, and test results show the smart substation performance meets and exceeds the substation reliability requirement. IntroductionAt present, China is undergoing the development of a large-scale strong solid power grid. The complexities of power systems associated with various operational modes, demands smart and intelligent apparatus, and more efficient information exchange at all levels. New substations should be built in a new way, in order to facilitate easy engineering, shorten installation and commissioning time, and be capable of performing incremental upgrades in the future in a flexible and robust way. The new national-wide initiative for smart substations aims at tapping to the latest technology available for innovative solutions [1] [2].The global standard IEC 61850 facilitates seamless information exchange between apparatus and the network based secondary system. Moving towards an information highway for protection, control, automation and beyond, opens up a world of opportunities in engineering, construction, commissioning, operation and maintenance. With the ample proof of its significant savings incurred in thousands projects world-wide [3]-[5], IEC 61850 based smart substation solutions are proven to be viable and cost effective [6]-[8].This paper investigates an IEC 61850 related smart substation solution, where intelligent field interface units (FAIUs) are employed to transfer conventional current/voltage transformers and outdoor switchgears into smart

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