Performance of Differential Protection Applied to Collector Cables of Offshore Wind Farms with MMC-HVDC Transmission

TL;DR

This paper evaluates the effectiveness of differential protection schemes for offshore wind farm collector cables with MMC-HVDC, highlighting challenges posed by inverter-based resources and proposing enhanced strategies for reliable fault detection.

Contribution

It analyzes the limitations of conventional differential protection in MMC-HVDC offshore wind systems and compares them with improved methods considering sequence components.

Findings

Conventional differential protection faces challenges with inverter-based resources.

Enhanced protection strategies improve fault detection sensitivity.

Simulation results guide better protection design for future grids.

Abstract

The ongoing global transition towards low-carbon energy has propelled the integration of offshore wind farms, which, when combined with Modular Multilevel Converter-based High-Voltage Direct Current (MMC-HVDC) transmission, present unique challenges for power system protection. In collector cables connecting wind turbines to offshore MMC, both ends are supplied by Inverter-Based Resources (IBRs), which modify the magnitude and characteristics of fault currents. In this context, this paper investigates the limitations of conventional differential protection schemes under such conditions and compares them with enhanced strategies that account for sequence components. Using electromagnetic transient simulations of a representative offshore wind farm modeled in PSCAD/EMTDC software, internal and external fault scenarios are assessed, varying fault types and resistances. The comparative evaluation provides insights into the sensitivity and selectivity of differential protection and guides a deeper conceptual understanding of the evolving protection challenges inherent to future converter-dominated grids.