New control approach for high performance of offshore wind farm under DC fault using three-level NPC VSC-HVDC and DC chopper

摘要

In this paper new control approach to achieve high performance under DC fault using three-level NPC voltage source converter based high voltage direct current (VSC-HVDC) transmission for offshore wind farm, are proposed. The proposed configuration allows optimal integration of highly distributed large scale offshore wind farm and demonstrates good performance of VSC-HVDC under presence of quickly cleared DC line fault. Furthermore, it is able to maintain stable operation of the existing power converters. The proposed control is based on detection of the positive to ground fault by measuring the level of cable voltage and the derivatives of the DC voltage and current. In addition, the protection control action of DC chopper extinguishes the fault current to restore the power transmission after the fault has been cleared, improving network reliability and power quality. Modeling and simulation tests are provided to validate the robustness of the proposed design, as well as, the developed control approaches.