A novel method of restoration path optimization for the AC-DC bulk power grid after a major blackout

Abstract

The restoration control of the modern alternating current-direct current (AC-DC) hybrid power grid after a major blackout is difficult and complex. Taking into account the interaction between the line-commutated converter high-voltage direct current (LCC-HVDC) and the AC power grid, this paper proposes a novel optimization method of restoration path to reconfigure the skeleton network for the blackout power grid. Based on the system strength, the supporting capability of the AC power grid for the LCC-HVDC is first analysed from the aspects of start-up and operation of LCC-HVDCs. Subsequently, the quantitative relationship between the restoration path and the restoration characteristic of LCC-HVDC is derived in detail based on the system strength indices of the short-circuit capacity and the frequency regulation capability. Then, an optimization model of restoration path considering non-tree paths is formulated and a feasible optimization algorithm is proposed to achieve the optimal path restoration scheme. A modified IEEE 39-bus system and a partial power grid of Southwest China are simulated to show that the proposed method is suitable for the restoration of AC-DC power grids and can improve restoration efficiency. This research can be an important guidance for operators to rapidly restore the AC-DC power grid.