Dynamic modelling and control of a micro-CHP system based on a light-duty SI-ICE fuelled by methane and green hydrogen blends for hybrid energy grid applications

Abstract

The paper focuses on the modelling, control and analysis of a micro-combined heat and power plant based on a light-duty (1.6 liter, four-cylinder) spark-ignition internal combustion engine fuelled by methane and (green) hydrogen blends. The engine is modelled and simulated using advanced predictive one-dimensional commercial codes with the combustion process tailored to reflect the characteristics of methane–hydrogen mixtures. The electrical machine connected to the engine is described through established equivalent electrical circuit equations for a three-phase permanent magnet synchronous machine with sinusoidal flux. The recoverable thermal power from engine waste heat is estimated using a model that combines simulation results and literature data. A robust model-based control system, adaptable to variations in hydrogen content, is designed and numerically validated. The paper provides a comprehensive characterisation of the system under different steady-state and dynamic power loads, as well as varying hydrogen concentrations. A novel primary energy savings index is introduced to evaluate the cogeneration benefits when green hydrogen is mixed with fossil fuels for engine fuelling. The proposed micro-combined heat and power system can also function as a programmable power source, mitigating the non-programmability of renewable energy sources. The developed model enables the analysis of hybrid energy grids scenarios, promoting the sustainable use of mixed renewable and fossil fuels.

Keywords

• Combined heat and power
• Internal combustion engine
• Hydrogen
• Modelling
• Automatic control
• Hybrid energy grids