DC-link voltage regulation in all-DC offshore wind farms

Offshore wind farms located far from the shore currently use AC-based collection systems with bulky line frequency transformers. Due to limited space, this approach is challenging and expensive. As an alternative, Medium Voltage DC (MVDC) collector systems have been proposed as a cost-effective solution for integrating offshore wind farms. One crucial area of research for these systems is DC-link voltage regulation to ensure safe, reliable, and stable operation of the entire system. In this study, an adaptive voltage regulator is designed to stabilize low low-voltage DC-link around the nominal voltage against disturbances. Additionally, current observers are suggested to eliminate the need for current sensors, increasing reliability and reducing implementation costs. To validate the control method and test the observer’s performance, simulations and Hardware-in-the-Loop tests (HIL) were conducted on a 10-MW wind turbine.