A Power Balancing Strategy of Virtual Asynchronous Machine/Synchronous Generator for STEM During Full Operating Conditions

The solar thermoelectric module (STEM) serves as a versatile interface for the conversion between thermal and electrical energy. It typically operates in two modes: thermoelectric heater (TEH) and thermoelectric generator (TEG). However, traditional control methods, such as the virtual synchronous generator (VSG), primarily focus on power balance in TEG mode. The potential of STEM in TEH mode for grid regulation is often overlooked. Therefore, this paper proposes a novel control strategy for STEM to achieve power balance during both power generation and load operation. Firstly, a thermodynamic model of the STEM considering the Thomson effect and external heat exchange is developed. Secondly, this paper develops a unified equivalent circuit based on the thermodynamic models and rated operating parameters of TEG and TEH. The equivalent circuit supports the bidirectional operation of the STEM. Moreover, a source–load seamless-switching control strategy for STEM is proposed, using VSG in TEG mode and the virtual asynchronous machine (VAM) in TEH mode. This enables STEM to achieve real-time power balance under all working modes. Finally, six operating scenarios are set for the proposed strategy, and the performance and effectiveness are verified through simulation and hardware-in-the-loop (HIL) experiments.