The North Sea Wind Power Hub (NSWPH) consortium was established in 2017 to cope with challenges associated planning and pre-development of hub-and-spoke projects based on a modular concept, utilizing HVDC building blocks of bipolar 2 GW 525 kV DC MMC converters with metallic return. NSWPH proposed a Simplistic Test Benchmarks (STB) methodology to define functional requirements and parameter ranges for these building blocks. This paper addresses several key DC grid control functional requirements, focusing on primary and secondary DC voltage controls, and post-fault active power recovery (PFAPR) to provide insights and recommendations. Primary DC voltage control, based on the DC voltage droop control scheme, is influenced by assigned droop gains and controller response speed. The paper proposes an analytical formula, supported by demonstrations using a STB model, and a systematic methodology for determining droop gains to ensure post-contingency voltage deviation constraints. Secondary DC voltage control requirements are discussed, highlighting the need for restoring voltage and adjusting power flow setpoints due to reduced security margins, demonstrated by a simulation. Lastly, a sensitivity analysis regarding PFAPR requirements is conducted, helping identify impacting factors to be considered in specifications, ultimately contributing to effective DC grid control strategies.
Kosei Shinoda, Pascal Torwelle; Ahmed Zama, ; Bertinato, Alberto; Van Doorn, Joris; Kryezi, Fitim
Presented at CIGRE B4-Colloquium Vienna 2023