A distributed feedforward control method for power electronic transformers

Because of its advantages such as small size and light weight, power electronic transformers (PET) are increasingly used in power transmission and distribution systems. The traditional centralized control method requires each cascaded power module to communicate with the central controller through a high-speed communication link, which increases the computational and communication burden of the central controller and reduces the expandability and modularity of a PET system. In this paper, a distributed feedforward control method for a cascaded H-bridge (CHB) converter-based PET is proposed. The pulse width modulation, input current regulation, voltage balance control, power balance control, output voltage regulation and output current regulation are assigned to the distributed local controllers. Therefore, the computational and communication burden of the central controller can be significantly reduced. The number of fibers connected to the central controller can be significantly reduced. Meanwhile, the proposed control method can greatly improve the dynamic response of the load disturbance, and a smooth start-up process of the PET system can be achieved. Simulation results are given to show the effectiveness of the proposed method.