HVDC Grid Post-DC Fault Recovery Enhancement

Fast and stable post-fault recovery is an essential part of a fault clearing strategy in HVDC grids. As the may involve de-blocking converters, unwanted oscillations be noticed voltages currents. These occur at resonant frequencies, which stem from interaction between converter grid. Methods to identify grid resonances exist, but focus mainly on control interactions instead during transient conditions such as recovery. This paper provides method analyze process, discusses their origins proposes two methods mitigate these. It found that these are due incompatibility converter- grid-side DC voltage moment de-blocking, low damping characteristic frequencies. The first mitigation approach acts aspect avoids triggering by matching de-blocking. second increasing DC-side through controls. Time domain simulations have shown both effectively reduce seen system