Abstract: Distribution network, located at the end of the power grid, is the direct link of power supply. However, frequent natural disasters have caused serious damage to the distribution network, resulting in large-scale and long-term power outage. The deployment and operation of distributed generation units with natural gas as energy plays an important role in improving the ability of distribution network to deal with natural disasters, but it also increases the interdependence between power grid and natural gas network. Therefore, it is particularly important to consider the cooperative operation of power grid and natural gas network. In this paper, a two-stage robust optimization model with a three-level optimization structure is proposed, which takes into account the uncertainty of line damage and the cooperative operation of power grid and natural gas network. Nonconvex natural gas flow constraints are relaxed into second-order cone (SOC) constraints, then the SOC-based column-and-constraint generation algorithm is employed to solve the proposed two-stage robust optimization problem. Simulations tested on 33-bus-6 node IEEE distribution test system show that the key distribution lines under the coordinated operation of power grid and natural gas network have a higher priority for hardening, and the rationality of considering the coordinated operation of power grid and natural gas network is verified.

Key words: distribution network; natural gas network; line hardeningdecision; robust optimization; second order cone relaxation