Choosing portfolios of reinforcement actions for distribution grids based on partial information

The cost-efficiency of individual reinforcement actions in mitigating risks of external hazards in distribution grids depends on the entire portfolio of implemented actions. Thus, when seeking to reinforce distribution grids, it is pertinent to assess portfolios of reinforcement actions to account for dependencies between them. Motivated by this recognition, we develop a systemic framework to support Distribution System Operators (DSOs) in allocating scarce resources to portfolios of reinforcement actions that help protect multiple grids against hazards in the light of complementary reliability indices. This decision problem is structured as an influence diagram that contains scenarios representing combinations of realizations for different types of hazards. For cases where scenario probabilities, perceived importance of the grids, and relevance of reliability indices are known, the framework solves a mixed-integer linear programming problem to determine optimal portfolios. If this is not the case, the framework accommodates partial information about these parameters. Building on this partial information, it computes all the non-dominated portfolios by obtaining optimal portfolios for specific parameters and screening the other feasible portfolios. The non-dominated portfolios are analyzed to guide the choice of reinforcement actions at different budget levels. The framework is illustrated with a case study where the DSO seeks to mitigate risks associated with three types of hazards in three distribution grids. The novelty of the proposed optimization-based framework lies in (i) combining Portfolio Decision Analysis (PDA) and reliability models to determine cost-efficient reinforcement portfolios and (ii) accommodating partial information about parameters required by PDA and reliability models.