Data and Model Hybrid Driven Non-Intrusive Wideband Impedance Measurement for LCC-HVDC Systems

Line commutated converter based high-voltage direct-current (LCC-HVDC) systems connected to weak grids are susceptible to wideband oscillations, threatening system stability. In this paper, a data driven modeling based non-intrusive wideband impedance measurement method is proposed for LCC-HVDC systems to monitor the dynamic characteristics of the receiving-end grid and assess the risk of wideband oscillations, without the need for additional primary equipment or external harmonic disturbances injection. First, the harmonic state-space (HSS) impedance model of LCC-HVDC is established, and the harmonic interaction mechanism between LCC system and the receiving-end grid is analyzed. Then, an impedance measurement method based on data-driven modeling is developed, incorporating an adaptive variable time-step (AVTS) sampling scheme and a dynamic frequency warping (DFW) technique to enable real-time assessment of oscillation risk profiles with reduced computational burden. Finally, the proposed method is validated by using the CIGRE benchmark system as well as the hardware-in-the-loop (HIL) tests.