Background Diesel generator (DG) sets are vital to modern power systems, providing critical power for various applications. Their performance is directly affected by the interaction between mechanical and electrical subsystems, which is often overlooked in existing studies. As DG sets advance toward increased power density and enhanced electromechanical integration, this interaction becomes a key bottleneck for further performance improvement. Purpose This study aims to investigate the interaction and underlying mechanisms between the mechanical and electrical subsystems, providing theoretical guidance for electromechanical co-design of DG sets, and thereby enhancing system stability and reliability. Methods To this end, an electromechanical coupling (EMC) model is proposed to characterize the interaction between the mechanical and electrical subsystems. This model is experimentally validated on a DG set under both steady-state and transient operating conditions, demonstrating prediction errors of less than 5.0%. A detailed analysis of the EMC characteristics is subsequently conducted to investigate their effects on the performance and stability of the DG set. Moreover, to enhance the impact resistance of the system, the influence of critical mechanical and electrical parameters is thoroughly examined. Results The results show that the mechanical and electrical subsystems interact to form a self-excited oscillatory system, exhibiting notable EMC effects that influence both vibration behavior and electrical dynamics of the DG set. These effects are particularly intensified under transient load conditions. Torque step changes under such conditions generate low-frequency broadband excitations that excite the first-order torsional mode (fN1), causing pronounced transient vibrations. Furthermore, parametric analysis reveals that reducing dynamic torsional stiffness (kTdyn) further exacerbates EMC effects. When kTdyn decreases to 75% of its original value, load disturbances induce severe EMC resonance, with extreme additional torque in the flexible coupling and current sidebands. Adjusting the engine speed controller PID parameters effectively suppresses fN1-related oscillations, preventing EMC resonance. Conclusion These findings advance electromechanical co-design of DG sets and facilitate the management of EMC-related faults, thereby ensuring their sustained reliability and efficiency in power generation, particularly in critical or demanding environments.

Dynamic Modeling and Electromechanical Coupling Characteristics Analysis in Diesel Generator Sets

期刊论文
发表日期：

2025年11月21日

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Jie Tao,
Lianghu Meng,
Jinyin Han,
Qi Yang,
Wanyou Li,
Yibin Guo

摘要

Background

Diesel generator (DG) sets are vital to modern power systems, providing critical power for various applications. Their performance is directly affected by the interaction between mechanical and electrical subsystems, which is often overlooked in existing studies. As DG sets advance toward increased power density and enhanced electromechanical integration, this interaction becomes a key bottleneck for further performance improvement.

Purpose

This study aims to investigate the interaction and underlying mechanisms between the mechanical and electrical subsystems, providing theoretical guidance for electromechanical co-design of DG sets, and thereby enhancing system stability and reliability.

Methods

To this end, an electromechanical coupling (EMC) model is proposed to characterize the interaction between the mechanical and electrical subsystems. This model is experimentally validated on a DG set under both steady-state and transient operating conditions, demonstrating prediction errors of less than 5.0%. A detailed analysis of the EMC characteristics is subsequently conducted to investigate their effects on the performance and stability of the DG set. Moreover, to enhance the impact resistance of the system, the influence of critical mechanical and electrical parameters is thoroughly examined.

Results

The results show that the mechanical and electrical subsystems interact to form a self-excited oscillatory system, exhibiting notable EMC effects that influence both vibration behavior and electrical dynamics of the DG set. These effects are particularly intensified under transient load conditions. Torque step changes under such conditions generate low-frequency broadband excitations that excite the first-order torsional mode (f_N1), causing pronounced transient vibrations. Furthermore, parametric analysis reveals that reducing dynamic torsional stiffness (k_Tdyn) further exacerbates EMC effects. When k_Tdyn decreases to 75% of its original value, load disturbances induce severe EMC resonance, with extreme additional torque in the flexible coupling and current sidebands. Adjusting the engine speed controller PID parameters effectively suppresses f_N1-related oscillations, preventing EMC resonance.

Conclusion

These findings advance electromechanical co-design of DG sets and facilitate the management of EMC-related faults, thereby ensuring their sustained reliability and efficiency in power generation, particularly in critical or demanding environments.