Photovoltaic LLC Converter Design and Droop Control of Metro Traction Power Supply System

With the rapid development of urban rail transit, the energy demand of subway system is increasing, and new energy is widely introduced in various fields. It has become the development trend of green urban rail to connect new energy sources such as photovoltaic power generation to the subway power supply system. Photovoltaic systems have complex nonlinear characteristics, so a DC/DC converter is a key technology for photovoltaic utilization. Directly connecting photovoltaics to the subway DC traction network has the advantages of high energy-saving benefits and low energy consumption, but it is also necessary to study its grid-connected control. Based on this background of photovoltaic access to subway 1500V DC, this paper designs an LLC resonant converter as photovoltaic converter, and uses a variable step disturbance observation method as the control method. After that, the droop control is studied for photovoltaic grid connection, and an improved droop control is used to realize a stable operation of the converter.