Hardware Implementation and Control Design of Generator Emulator in Multi-Converter System

In this project to develop a reconfigurable electrical grid emulator, a Hardware Test-Bed (HTB) is being developed that emulates large scale power system generators and loads by using power electronic converters. Source converters in the HTB system are designed to emulate generators. A synchronous generator model is implemented in the converter to calculate the voltage references in the dq axis, and a voltage controller is added to achieve zero steady state error. A traditional cascade controller with inner current control and outer voltage control brings additional output impedance to the generator model, and causes voltage tracking error during transients. To minimize the controller output impedance and eliminate controller influence on the generator model, a single voltage loop with current differential feedback is proposed in this paper. Combined with rescaled generator parameters, circulating current elimination, and dead time compensation, simulation and experiments are performed in the HTB. The results verify the effectiveness of the controller and demonstrate the dynamic generator emulator behavior.