With increasing interdependence among electricity

district heating

and natural gas systems in economy and physics

this paper focuses on the optimal bidding problem of a dominant gas-fired CHP unit in synchronized electricity-heat-gas markets with real-life step-wise energy offer format. Gas-fired CHP generators act as price makers and submit price-quantity offering curves in independently cleared electricity and district heating markets. A novel loss-embedded power flow model is proposed for market clearing which accounts for active power loss

congestion

reactive power flow

and voltage constraints. Adding penalty terms into the objective function eliminates additional binary variables

which eases computation burden. A two-stage trading mechanism is designed for gas-fired CHP generators to simultaneously participate in the multi-energy market. Based on a mathematical program with equilibrium constraints

an optimal bidding model is established in which the bilinear terms are eliminated by applying the binary expansion method. A diagonalization algorithm can be nested in the proposed trading mechanism if we intend to study the Nash equilibrium of the N-person Cournot oligopoly market. Numerical tests with different scales are carried out to validate the proposed methodology in detail.