  In order to improve dynamic characteristics of the power system with
high-proportion renewable energy sources (RESs), it is necessary for the
voltage source converter (VSC), interfaces of RESs, to provide inertial and
frequency regulation. In practical applications, VSCs are better to be
controlled as a current source due to its weak overcurrent capacity. According
to the characteristic, a dual synchronous theory is proposed to analyze the
synchronization between current sources in this paper. Based on dual
synchronous idea, a dual synchronous generator (DSG) control is applied in VSC
to form inertial current source. In addition, a braking control is embedded in
DSG control to improve the transient stability of VSC. Finally, experimental
results verify the effectiveness of the theory and the control method.
