Power shift‐based optimal corrective control for bipolar multi‐terminal high‐voltage direct current grid

Abstract

The bipolar modular multi-level converter-based multi-terminal high voltage direct current (MTDC) grid offers an attractive solution to cope with the increased renewable power generation integration and power transfer capability. However, the N − 1 outage of direct current transmission lines and converters may result in overloads of other components and renewable power generation congestion. This study presents a power shift-based optimal corrective control method to guarantee the operational security of the system with bipolar MTDC grid embedded. First, the principle of power shift in the bipolar MTDC grid is analysed. The grid features in isolated positive and negative poles and can provide up to 50% transmission redundancy. Following an N − 1 contingency, certain power can be shifted from the faulty pole to the healthy pole or between different converter stations. Second, two optimisation models are, respectively, established for the MTDC and alternating current grids to address the power shift-based optimal corrective control. The proposed method guarantees operational security of the system while the amount of renewable power generation accommodation by the MTDC grid is maximised. Finally, the method is applied to the real-life Zhangbei ±500 kV four-terminal bipolar high-voltage direct current grid. Numerical results and electromagnetic transient simulation verify the effectiveness of the presented method.