Modeling and Assessment of a Two-Stage Congestion Management Framework Based on Temporary Admissible Thermal Loading and Corrective HVDC Control

The increasing penetration of renewable energy sources has intensified transmission congestion in modern power systems, primarily due to the spatial mismatch between generation and demand. Conventional congestion management relies on preventive redispatch constrained by Permanent Admissible Transmission Loading (PATL), which ensures system security but often leads to high redispatch volumes and increased operational costs. This thesis investigates a two-stage congestion management framework that enhances transmission utilization by allowing temporary line loadings up to Temporary Admissible Transmission Loading (TATL) and subsequently resolving overloads using corrective High Voltage Direct Current (HVDC) control, supplemented by curative redispatch if necessary.
The proposed framework is implemented on a modified IEEE 30-bus test system using a DC optimal power flow (DC-OPF) formulation. A comparative analysis is performed against a purely preventive PATL-constrained base model over a time series of 480 timesteps representing varying load and wind generation conditions. The methodology integrates PTDF-based HVDC corrective actions and examines the impact of key parameters such as TATL margin and curative HVDC reserve allocation.
Results show that the proposed framework can reduce cumulative redispatch volume by up to 14% under the reference configuration, with further improvements observed under relaxed HVDC reserve constraints. The effectiveness of the approach is strongly dependent on operating conditions, network topology, and the sensitivity of congested lines to HVDC control. While larger TATL margins increase redispatch savings, they also lead to a higher share of curative redispatch, highlighting a trade-off between economic efficiency and operational robustness. The allocation of HVDC capacity between preventive and curative stages is identified as a critical factor influencing performance.
Overall, the study demonstrates that coordinated use of temporary thermal loading margins and fast corrective HVDC control can significantly improve congestion management efficiency compared to conventional preventive strategies. However, optimal configuration requires balancing redispatch reduction with the availability of corrective flexibility to ensure secure operation.