Cut-sets pre-screening for adaptive splitting control of AC/DC power systems

Adaptive islanding control is applied to preventing the collapse of a large-scale interconnected power gird. However, opening lines when the system is in emergency state also brings about disturbances such as three-phase voltage asymmetry (TPVA), which may lead to commutation failures (CFs) of high voltage direct current (HVDC). This article presents a practical method to determine the crucial AC buses which are of great impact on the safe operation of HVDC, and the lines that connect to the buses should be excluded from the splitting cut-set. A TPVA index for each bus is proposed first. After that, a dependency matrix is constructed to describe the relationship between an AC bus and the TPVA indices of other buses including those in HVDC converter stations. Based on the dependency matrix, K-core decomposition is used to find crucial buses. Finally, the method is validated by simulation on Guangdong power grid.