Pole-Phase Transformation for AC/DC Hybrid Power Grids

AC/DC hybrid power grid is the new form of power grid development. The traditional analysis method of AC power grid is not suitable for AC/DC hybrid power grid. DC transmission system can be regarded as a two-port network. Thus it must be equivalent to an AC circuit and problems in AC/DC hybrid grids can be simplified to them in AC grids. Take this idea, the paper has done some preliminary works: based on LCC-HVDC under steady-state, a method of equivalent DC lines and converter stations to three-phase AC lines is proposed, which is called pole-phase transformation. The effectiveness of the method is verified in the simulation of LCC-HVDC model. The simulation results show that AC/DC hybrid power grids with LCC-HVDC can be equivalent to an AC grid built by the proposed pole-phase transformation method in the steady state.