A modeling approach for AC/DC distribution systems based on average dynamic phasor method

Abstract

In order to achieve high-precision stability evaluation and time-domain simulation of AC/DC distribution systems, and improve the analysis efficiency of complex systems, an average dynamic phasor modeling method of AC/DC distribution systems was proposed with considering the current reconstruction of dual-active bridge (DAB) high frequency transformer and the error correction of phase shifting duty cycle. Based on the average dynamic phasor model of voltage source converters (VSCs) and DABs established, the equivalent phase shift duty cycle of DAB was used as a modified algebraic variable to reduce the deviation caused by ignoring high-order dynamic phasors in modeling process and Fourier series are used to reconstruct the winding current of the high frequency transformer, respectively, to realize the accurate characterization of the DC and AC variables in average dynamic phasor models. Then an expandable global model of AC/DC distribution systems has been established by introducing the distribution line equations. Finally, according to the time-domain simulation based on MATLAB/Simulink software, the influence of model stability when the operating frequency and the leakage inductance of high frequency transformer changes was analyzed, and the correctness and accuracy of the proposed average dynamic phasor model was verified under the two scenarios of load mutation and disconnection fault.

Keywords

• AC/DC distribution system
• Average dynamic phasor
• Voltage-source converter
• Dual-active bridge
• Current reconstruction
• Single phase shift modulation