Robust black start of an offshore wind farm with DRU based HVDC link using power synchronization control

TL;DR

This paper presents a universal power synchronization controller for offshore wind farm HVDC links, enabling robust black start procedures by managing delays and power sharing with a novel control approach.

Contribution

It introduces a new power synchronization controller with voltage-power droop and virtual power concepts for stable offshore wind farm black start operations.

Findings

Controller effectively manages large delays during black start.

Ensures balanced power sharing and stable operation.

Case studies confirm robustness of the proposed method.

Abstract

This paper introduces a universal power synchronization controller for grid-side control of the wind turbine conversion systems in an offshore wind farm with a diode rectifier in the offshore substation of the HVDC link. The controller incorporates voltage-power droop controllers in the outer loop to enable the operation of this setup. To effectively handle the impact of large delays during black start and power ramp phases, virtual active and reactive power quantities are defined. These quantities are computed based on the current references prior to any modifications that might be needed to meet converter current and voltage limits or source constraints. Utilizing them in the outer loop ensures a balanced power sharing and a stable operation whenever the original (unmodified) current references are not realized. Case studies confirm the robustness of the proposed controller.