Hierarchical Optimization of Integrated RES-NG Provider Participating in Multi-Type Markets with Dynamic HCNG Pricing

With the deployment of Hydrogen-enriched Compressed Natural Gas (HCNG) technology, establishing market mechanisms adapted to its physical characteristics is crucial for renewable energy accommodation. However, existing studies lack HCNG pricing mechanisms that reflect calorific value fluctuations and often overlook the dynamic carbon emission characteristics of Hydrogen Mixed Gas Turbines (HMGTs). To address these gaps, this paper proposes a hierarchical optimization framework for Integrated RES-NG Providers (IRNPs) participating in multi-type markets. In the upper level, a bidding model involving electricity, HCNG, hydrogen, and CEP-GEC joint markets is established. A dynamic HCNG pricing mechanism based on the Wobbe Index is introduced to capture composition variations, and a refined HMGT model based on the modified Arrhenius equation is employed to quantify combustion-emission physicochemical kinetics. The lower level formulates market clearing models for social welfare maximization, which are transformed into a Mathematical Program with Equilibrium Constraints (MPEC) via KKT conditions. Case studies demonstrate that: (1) the refined HMGT model captures the dynamic fluctuation of the carbon emission factor between 0.6074 and 0.6216, correcting the bias of traditional static models; (2) the introduction of the dynamic HCNG pricing mechanism significantly enhances flexibility, increasing the renewable energy accommodation rate from 90.47% to 100%; (3) IRNPs maximize profits through multi-market arbitrage, achieving a daily total revenue of ¥2.231 million, a 30.9% increase compared to participating only in electricity–gas markets; (4) The critical thresholds for cross-market arbitrage are identified, and hydrogen is diverted to the hydrogen market when prices exceed 9.6 ¥/kg and completely prioritized over HCNG blending when prices surpass 15.6 ¥/kg.