Browsing by Author "Saarinen, Ilmari"

Now showing 1 - 1 of 1

Robustness analysis for reinforcement actions in distribution grids
(2024-01-10) Saarinen, Ilmari
Perustieteiden korkeakoulu | Bachelor's thesis
Electricity distribution networks are a crucial part of critical infrastructure. Thus, making them as reliable as possible is a priority for the distribution system operator (DSO). External hazards, such as weather conditions and cyber-attacks, threaten the reliability of distribution grids. The DSO can protect the distribution system against these hazards by selecting combinations of reinforcement actions. The portfolio of reinforcement actions, which maximizes system reliability on a certain budget level, can be constructed by portfolio decision analysis (PDA) techniques. Finding optimal portfolios of reinforcement actions requires precise estimation of reinforcement actions' effectiveness and hazards' severity. Accurate estimation is not always possible, e.g. due to a lack of information about certain hazards. Performing robustness and sensitivity analysis helps understand how the reinforcement actions' and hazards' uncertain parameters affect the reliability of distribution grids. In this thesis, the stability of the optimal portfolio of reinforcement actions is examined by changing how much reinforcement actions improve the distribution system's reliability and how much hazards decrease it. By the stability of the portfolio, we mean how the optimal actions change due to these modifications in the effectiveness of actions or severity of hazards. Robust actions, which are used in most reinforcement strategies, are identified. Studying the robustness of the selection process helps the DSO to exclude redundant actions from the set of possible actions, which makes the problem of choosing an optimal portfolio more efficient. The sensitivity of the reliability is studied by making a first-stage decision to apply reinforcement actions following changes in the effectiveness of actions or hazards. The reliability of the system with original actions and hazards is then compared to its reliability with the changed actions or hazards. Hazard and action parameters, which affect the reliability most, can be identified. This can help the DSO to determine which parameter accuracy improvements to prioritize.