Power Flow Calculation and Operating Parameter Optimization of Fractional Frequency Power Transmission System

Fractional frequency Transmission System (FFTS) owns the advantages of traditional High Voltage AC (HVAC) and High Voltage DC (HVDC) Transmission systems, and can meet the grid-connected demands of large-capacity and long-distance offshore wind farms. The power flow calculation model for a novel Modular Multilevel Matrix Converter is proposed, based on which the alternating iterative power flow algorithm for AC-AC hybrid system with FFTS is designed. With this method, the voltage fluctuation and reactive power compensation of FFTS and HVAC system are calculated and compared through two cases. In order to reduce the power loss and make full use of flexible parameters in FFTS, two dynamic optimal operation schemes are proposed and their unified equations are derived, which apparently decrease power loss in the two cases.