The synergies between electricity and other energy resources could promote energy utilization efficiency in electricity market. Within this context

this paper proposes a bi-level stochastic optimization model for the joint operation of a coordinated wind power plant (WPP) and natural gas generating (NGG)-power to gas (P2G) suppliers participating in the day-ahead (DA) market and real-time (RT) market as well as providing real-time auxiliary services. The coordinated supplier's payoff is maximized in the upper level with consideration of the uncertainties of WPP output capacity and RT electricity price

while the social welfare of the grid is maximized in the lower level. Simulation results demonstrate the effectiveness of the proposed bidding model of the coordinated WPPs and NGG-P2G suppliers by examining its bidding behaviors and benefits with comparisons of four other bidding models.