Multi-stage Optimization of Inter-regional Flexibility with HVDC Tie-line

Renewable energy resources are often far from load centers, requiring long-distance power transmission. High-voltage direct current (HVDC) tie-line is successful deployed in many countries in recent years, and is expected to deliver more renewable energy. This work proposes a novel multistage HVDC transmission planning model, aiming to unlock the potential flexibility in the HVDC transmission system and increase the renewable penetration. We focus on the inter-regional flexibility, which can be delivered by HVDC. A multistage recourse action is employed to guarantee the solution robustness and nonanticipativity. Implicit decision method is developed to solve the problem. We perform the case study in a real-world inter-regional grid. Numerical results show that the proposed approach unlocks more inter-regional flexibility and helps increase the renewable hosting capacity.