Stability Analysis and Collaborative Optimization of All-DC Offshore Wind Renewable Energy

Series-connected-based offshore wind farms have the advantages of low cost and large capacity, and has been widely used in grid. The power of series-connected-based offshore wind farms can be transport by voltage source converter based high voltage direct current transmission (VSC-HVDC) efficiently. The stability of VSC-HVDC-based DC collecting system of offshore wind farms gets attention from society. This paper develops the output analytical impedance model of VSC-HVDC-based DC collection system, including HVDC transmission line, VSC-HVDC receiving-side inverter station and the AC grid based on the harmonic linearization method. Analyzing the oscillation mechanism of VSC-HVDC-based DC collecting system of PMSG-based offshore wind farms by impedance models characteristic analysis. The research provides a theoretical basis for the construction and stable operation of all-DC offshore wind farms in the future.