This paper presents a flexible model for microgrid formation in the integrated electricity-gas system by optimal sizing, siting and operation of combined heat and power (CHPs) in order to improve the system operation/resilience and reduce the operational/energy cost. The resilience is defined in terms of critical load restoration following events. The upstream grid blackout, CHP outage and power line outage are modeled as the events. All the power lines (32 lines of the grid) may be subject to outage. The events are applied on the system as single event as well as consecutive events. The system is designed to be able to handle all these events. Under the events, the grid is sectionalized into several microgrids. The created microgrids are allowed to change their structure under different single and multiple disruptions. The partial and full overlap between the microgrids is modeled and studied. The results demonstrate that the end-buses of the grid are the best locations for CHPs in order to achieve the defined objectives all together. The CHPs reduce the overall cost by 11.6 % and supply all critical loads under single and multiple events.
