Analysis of bidirectional 15 MW current source DC/DC converter for series-connected superconducting-based 1 GW/100 kV offshore wind farm

A wind farm with series de collection can potentially eliminate the costly offshore platform and its step-up components. Multiple series strings can be connected in parallel to extend the power capacity for a given voltage. In such arrangement, the DC/DC converters for individual generators are rated at only a fraction of the transmission voltage. The maturity of superconducting cable technology will eliminate the difficulty of transmission losses with high current low voltage systems. This paper presents a feasibility study on the DC/DC converter design for a parallel-series-connected wind farm. The isolated front-to-front (F2F) mixed voltage source converter (VSC) and current source converter (CSC) is examined with power back-feeding capability during wind calm periods for a 15 MW generator. A novel configuration using 3-level (3L) VSC and thyristor-based CSC with combinational control of AC voltage magnitude, frequency, and thyristor delay angle is proposed and evaluated for a 1 GW/100 kV parallel/series wind farm based on the superconducting cable. Detailed converter model including power loss estimation in PSCAD is presented to support the converter design recommendations.

Automated summary

This paper introduces a feasibility study on the design of DC/DC converters for a wind farm with series connections, where multiple series strings can be connected in parallel to increase power capacity. The advantages of using superconducting cable technology in wind power systems to reduce transmission losses are also examined.