Design of a Parallel All-DC Wind Power System With Turbine-Side Boost Based on a New DC Conversion

Abstract

All-DC wind power system is one of the important directions of wind power development in the future, and its safe and reliable topology and stable control strategy are the key to the stable operation of the system. In order to solve the problems of poor control flexibility, difficulty of self-starting and low reliability of DC fault crossing in the current all-DC wind farm, this paper presented a topological structure of the parallel all-DC wind power system with turbine-side boost based on a new DC conversion. Based on the dynamic connection mode that each bridge arm of the new DC converter was charged in parallel on the low voltage side and discharged in series on the high voltage side, this paper designed the control strategy of the all-DC wind farm and analysed the operation mode of the all-DC wind farm in the steady state operation stage, the self-starting stage and the DC fault crossing period. Based on PSCAD/EMTDC, the simulation model of the parallel all-DC wind power system with turbine-side boost based on a new DC converter was established. Through the simulation of all-DC wind farm under normal operating conditions, such as steady state and dynamic operation, and fault conditions, such as dynamic cut-in and cut-out of faulty wind turbine and short circuit of DC bus, it was verified that the topology structure of the proposed parallel all-DC wind power system with turbine-side boost based on a new DC converter could improve the control flexibility, reduce the difficulty of self-starting, and ensure the high reliability of DC fault crossing under the premise of feasibility.INDEX TERMS All-DC wind power system, new DC converter, parallel, topological structure, control strategy.