Identification and suppression methodology for wideband oscillations in LCC-MMC in UHVDC transmission system

Abstract The Hebei Province Ultra-High-Voltage-Direct Current transmission system is one of China’s first cross-provincial transmission channels designed to support large-scale wind and photovoltaic power bases in desert, Gobi, and barren regions. However, the system faces stability challenges due to wideband oscillations caused by renewable energy fluctuations transmitted through the DC system and the integration of large-capacity DC into the weak receiving-end grid. This paper systematically reviews the key technical difficulties of the project, analyzes the dynamic interaction between sending-end renewable power fluctuations and receiving-end load characteristics, and clarifies the excitation mechanism of wideband oscillations from the impedance and control characteristics of the LCC station. Furthermore, it examines the MMC station control strategy at the receiving end to reveal the mechanisms of oscillation generation, propagation, and suppression. The study aims to provide references for the development of renewable energy bases in arid regions and for AC/DC system planning in systems with high penetration of power electronics.