Abstract: Along with the promotion of carbon neutrality and clean heating in countryside areas，operational

flexibility plays a more important role in electric power systems. Following this trend，a novel method was proposed

for evaluating the flexibility of biogas driven combined heat and power（CHP）considering the thermal inertia of

district heating systems. First，the structure and operating scheme of the zero-carbon rural integrated energy system

were introduced. The biogas driven CHP，biogas storage system and district heating systems were modelled. On this

base，key performance indices and evaluation methodology were proposed to characterize the flexibility of this

system. To deal with the optimal control problem with time delays in flexibility evaluation，a decomposition and

aggregation method was proposed，which ensure the heat supply to buildings while supporting the operation of the electrical system. The results show that district heating systems enhance the flexibility of the CHP by accommodating the imbalance in heat supply and demand，also，the use of district heating system can help the operator avoid dumping heat when increasing the CHP power output.

      Key words: rural integrated energy system；biogas driven combined heat and power（CHP）；electricity

flexibility；district heating systems