Resilience Enhancement Strategies for Power Distribution Network Coupled With Urban Transportation System

Traffic lights play a critical role in mitigating traffic congestions, which can be energized by distributed generators (DGs) when power outages occur in urban areas. This paper studies the resilience enhancement strategy by line hardening and DG placement when outages occur in distribution lines and traffic lights in the coupled power distribution system and urban transportation system (PDS-UTS). A tri-level optimization model is formulated with a limited budget for line hardening and DG placement to minimize the cost of load shedding and aggregated vehicle travel time. The first level determines line hardening and DG placement strategies, the second level searches for the worst case of faulted lines that would maximize load shedding and aggregated vehicle travel time, and the third level minimizes the corresponding costs of load shedding and travel. In urban transportation system, a dynamic user equilibrium model is established in a cell transmission model and solved by a linear complementarity approach. As the number of unavailable lines and traffic lights are definite in the inner-most level, the coupled PDS-UTS is considered as two decoupled systems. Accordingly, the tri-level model is converted into an equivalent bi-level model through Karush-Kuhn-Tucker conditions, which is then solved by a greedy search method. Case studies corroborate the effectiveness of the proposed model and relevant solution method for the coupled PDS-UTS.