  In energy systems with high shares of weather-driven renewable power sources,
gas-fired power plants can serve as a back-up technology to ensure security of
supply and provide short-term flexibility. Therefore, a tighter coordination
between electricity and natural gas networks is foreseen. In this work, we
examine different levels of coordination in terms of system integration and
time coupling of trading floors. We propose an integrated operational model for
electricity and natural gas systems under uncertain power supply by applying
two-stage stochastic programming. This formulation co-optimizes day-ahead and
real-time dispatch of both energy systems and aims at minimizing the total
expected cost. Additionally, two deterministic models, one of an integrated
energy system and one that treats the two systems independently, are presented.
We utilize a formulation that considers the linepack of the natural gas system,
while it results in a tractable mixed-integer linear programming (MILP) model.
Our analysis demonstrates the effectiveness of the proposed model in
accommodating high shares of renewables and the importance of proper natural
gas system modeling in short-term operations to reveal valuable flexibility of
the natural gas system. Moreover, we identify the coordination parameters
between the two markets and show their impact on the system's operation and
dispatch.
