Performance study of solid state transformer applying BP artificial neural network PID regulator

On the basis of its working principle and topology, a mathematical model of three-phase AC-DC-AC-type solid state transformer is built. The control strategies of the AC-DC rectifier, DC-DC converter and DC-AC inverter are studied respectively. Due to the nonlinearity and time-varying uncertainty in a SST system, it is difficult to get a precise model, resulting in the unsatisfactory control results gained via adopting the traditional PID regulator. To enhance the robustness and adaptability of the SST system, a neural network PID controller is designed which modifies the proportional coefficient, integral coefficient and differential coefficient in the real-time online adjustment process. A simulation model is constructed based on Simulink and the results show that the SST model can achieve unit input power factor, constant output voltage and stability against load variation and grid disturbance.