A multi-objective NCUC model co-optimizing GHG emissions and market costs using multiple ancillary services in high-renewable systems

The dual challenge of decarbonization and reduction of network operating costs remains a critical focus for power system operators and researchers. This article addresses this challenge by proposing an operational framework that co-optimizes greenhouse gas (GHG) emission reduction and operational cost (OC) minimization through the simultaneous implementation of day-ahead energy and spinning reserve markets. The framework is formulated as a multi-objective network-constrained unit commitment (NCUC) problem designed for systems with high penetration of wind and solar generation. To achieve these objectives, the study incorporates multiple ancillary services, including demand response (DR), battery energy storage transportation (BEST), and transmission switching (TS). Furthermore, the framework examines two critical aspects: the impact of network security on GHG emissions and the effect of emission taxation policies. These investigations are conducted through three distinct methodological approaches implemented on a modified IEEE RTS-79 24-bus test system. Simulation results demonstrate that the proposed framework successfully achieves simultaneous reduction of GHG emissions and operational costs across all three approaches, validating the effectiveness of coordinated ancillary service implementation in high-renewable power systems.