Gao Changwei, Sun Yongchang, Zheng Weiqiang, Wang Wei
College of Electrical and Automation Engineering, Liaoning Institute of Science and Technology, Benxi, 117004, China.
Dalian Economic and Technological Development Zone Heat Supply Co., LTD, Dalian, 116600, China.
Sci Rep. 2023 Aug 3;13(1):12598. doi: 10.1038/s41598-023-39121-6.
In the parallel supply system of synchronous generator and virtual synchronous generator, the physical structure and control structure of the two kinds of power supply are quite different, and it is difficult to distribute the transient power of the two kinds of power supply evenly when the load changes abruptly. Especially in the case of sudden load increase, virtual synchronous generator bears too much load in the transient process because of its fast adjustment speed, and even causes short-term overload, which makes the capacity of virtual synchronous generator can not be fully utilized. In view of this problem, firstly, the mechanism of transient power uneven distribution of two heterogeneous power sources is explained from the differences of frequency modulation, voltage regulation and output impedance. Secondly, virtual speed regulation, virtual excitation and dynamic virtual impedance are added to the traditional virtual synchronous generator control to simulate the speed regulation characteristics and electromagnetic transient characteristics of the synchronous generator, so as to realize the transient and steady-state power equalization between heterogeneous power supplies when the virtual synchronous generator and the synchronous generator run in parallel. Thirdly, in order to ensure the fast dynamic response characteristics of the virtual synchronous generator in independent operation mode, the traditional virtual synchronous generator control algorithm is still maintained in independent operation mode, and the mode switching control link based on state tracking is designed to realize smooth switching between the two working modes. Finally, the hardware in loop experiment results based on RT-LAB show that the proposed control method can realize the transient and steady-state power equalization when the virtual synchronous generator and the synchronous generator operate in parallel, it can keep the fast voltage regulation and frequency modulation ability when the virtual synchronous generator operates independently, and can realize smooth switching between independent and parallel operation modes.
在同步发电机与虚拟同步发电机的并联供电系统中，两种电源的物理结构和控制结构差异较大，当负载突然变化时，难以均匀分配两种电源的暂态功率。特别是在负载突然增加的情况下，虚拟同步发电机由于调节速度快，在暂态过程中承担了过多负载，甚至导致短期过载，使得虚拟同步发电机的容量无法得到充分利用。针对这一问题，首先从调频、调压和输出阻抗的差异出发，解释了两种异构电源暂态功率分配不均的机理。其次，在传统虚拟同步发电机控制中加入虚拟调速、虚拟励磁和动态虚拟阻抗，以模拟同步发电机的调速特性和电磁暂态特性，从而在虚拟同步发电机与同步发电机并联运行时，实现异构电源间的暂态和稳态功率均衡。第三，为确保虚拟同步发电机在独立运行模式下具有快速的动态响应特性，在独立运行模式下仍维持传统虚拟同步发电机控制算法，并设计基于状态跟踪的模式切换控制环节，实现两种工作模式的平滑切换。最后，基于RT-LAB的硬件在环实验结果表明，所提控制方法能够在虚拟同步发电机与同步发电机并联运行时实现暂态和稳态功率均衡，在虚拟同步发电机独立运行时能够保持快速的调压和调频能力，并能实现独立与并联运行模式间的平滑切换。
