Research on Control Strategy of Solid State Transformer Based on Improved MPC Method

Abstract

As the core equipment of smart grid, solid-state transformer (SST) needs to have good power quality regulation capability under grid side faults and load side faults. To ensure that the high-voltage side converter works at unity power factor and smooth DC voltage. At the same time, the three-phase output voltages need to have high steady-state accuracy and strong anti-interference capability. In this paper, an improved model predictive control scheme was proposed. First, a theoretical modeling analysis of the high and low voltage side of a solid-state transformer was performed. Then, power and voltage prediction models are developed for the high-voltage side converter and low-voltage side converter of the SST, respectively. Three voltage vectors are selected for prediction by the cost function, and the equivalent voltage vector in the two-phase stationary coordinate system is synthesized and modulated to control the converter. Finally, simulation was conducted to compare and analyze various operating conditions of SST under different control schemes. The control effect of solid-state transformer under improved model predictive control is better than traditional finite control set model predictive control and proportional integral control, which can better regulate power quality.

Keywords

• Solid-state transformer
• model predictive control
• three-vector
• two-phase stationary coordinate system