Control strategy of series–parallel DC wind farm with fault isolation

Abstract

The series–parallel DC wind farm composed of a large number of DC wind turbine (DCWT) is a potential scheme for offshore wind power collection with lower construction costs and power losses. However, enhanced coupling issues, such as energy curtailment and fault isolation, exist in the DC wind farm. To overcome the difficulties, a series–parallel DC collection system is proposed, where DCWTs based on the single active bridge (SAB) are connected in series and then are connected in parallel via DC/DC converters. The coupling mechanism among series–parallel strings is analyzed first, and a coordinate control strategy for the whole system is proposed based on the characteristics of SAB. DC fault located at different strings is analyzed and strategies are proposed to protect the whole system. Simulation results in PSCAD/EMTDC verifies the proposed control strategy with the less coupling among series–parallel DC wind farms under unequal wind speeds and fault.