Two-layer recovery strategy of active distribution networks with the integration of hydrogen and natural gas systems

The integration and application of hydrogen energy can significantly enhance the resilience and self-healing capability of distribution networks under extreme events. In this work, with the coordination of hydrogen, natural gas and electricity as well as the collaboration of multiple resources such as mobile emergency resources (MERs), hydrogen refueling stations (HRSs), and hydrogen-mixed gas turbines (HMGTs) considered, a two-layer recovery strategy is proposed for the pre-event and post-event resilience enhancement of the active distribution network (ADN). In the pre-event layer, a two-stage robust deployment model for positioning MERs and repair crews (RCs) in advance for quick reactions to extreme events is presented considering the uncertainty of faulted conditions. In the post-event layer, a robust restoration model incorporating multiple emergency resources, hydrogen energy, network reconfigurations, and the coordination between the ADN and the hydrogen-enriched compressed natural gas network (HCNGN) is proposed to attain an efficient restoration scheme. A node-based temporal-spatial network model is presented to represent the movement patterns of MERs and RCs in the two-layer recovery strategy. To improve the computational efficiency of the proposed robust models, a customized solution algorithm based on the Nested Column-and-Constraint Generation method is used. Simulations results show the proposed two-layer recovery strategy decreases the total unserved load by 72.3% and 81.6% compared with the strategies without pre-event deployment and without considering HRSs and HCNG, which demonstrate the effectiveness of the two-layer recovery strategy.