Interactions analysis and quadrature voltage compensation control for stabilizing LCC-HVDC system with multiple STATCOMs

•The interaction paths among LCC, STATCOMs and weak AC network are presented. Then, the impacts of the interactions among them on the system damping characteristic and oscillation modes are further analyzed.•A stability-enhancing control called quadrature voltage compensation control is proposed, which is easy to implement and will not slow down response speed of STATCOM.•The physical explanations on the instability caused by increasing the number of online STATCOMs are given from two physical perspectives, which help in understanding such unstable phenomenon intuitively and easily.