After large-scale wind power and photovoltaic power is connected with the grid, the inherent intermittent and volatility of wind power and photovoltaic power may have adversely affects on the security and stability of power grid. With the rapid development of wind power and photovoltaic power generation, this problem is increasingly outstanding. So it is very important to development the technology research of large-scale battery energy storage system (BESS). The article respectively carried out comparative analysis on the converter and the filter, which were the components of power conversion system (PCS) as an important component of BESS. Based on the existing battery technology, the results show that the converter only containing DC/AC link and the converter containing Z-source network and DC/AC link both have the characteristics of higher energy conversion efficiency and simple control, compared with traditional converter which contains DC/DC link and DC/AC link. Compared with the traditional L filter and LC filter, the LCL filter can restrain high harmonics better, effectively reduce the inductance value, improve the dynamic performance of the system, and be less affected by the grid. Combined with analysis conclusion, the article put forward two new topological structures of PCS.