Work

Frequency Response Characteristics Analysis and Inertia Enhancement Methods of Free Piston Stirling Generator in Islanded Microgrid

Year: 2026

Type: article

Abstract: ABSTRACT Dish‐Stirling solar‐thermal generation is a highly promising sustainable development technology. As its power conversion unit, the free piston Stirling generator (FPSG) possesses excellent inertia support capability and a high overload margin, effectively improving the frequency stability of an islanded microgrid (MG). However, FPSG is essentially a strongly coupled thermo‐mechanical‐electrical high‐order nonlinear system with complex dynamic characteristics, making its frequency response mechanism difficult to characterise precisely. This poses challenges for the accurate analysis of its key influencing parameters, thereby limiting further improvement of its inertia support capacity. In light of this, the Schmidt model is first simplified to derive the relationship between frequency deviation and design parameters. Based on this, the Morris screening method is employed for sensitivity analysis. By revealing the underlying mechanism, an adaptive cooperative inertia support control strategy is proposed. This method alters the output characteristics of the FPSG by adjusting spring stiffness and achieves efficient coordination with energy storage systems (ESS), thereby significantly enhancing the reliability of the power supply system. Finally, the effectiveness of the proposed method is validated at both the single and system levels, which indicate that the frequency nadir and the rate of change of frequency (RoCoF) can be improved by 25.58% and 34.38%.

Source: IET Renewable Power Generation

DOI: 10.1049/rpg2.70393