基于虚拟同步机的微网逆变器无频差控制

Method of Frequent Deviation-Free Control of Microgrid Inverter Based on Virtual Synchronous Generator Control

虚拟同步机控制可克服传统并网逆变器无惯性给电网带来的冲击,可提升电网接纳可再生能源的能力,在微电网中受到了广泛关注。但由于虚拟同步机采用传统的有功?频率下垂控制,在孤网模式下存在频率偏移,这会对接入微网中的负载产生不利的影响。提出了一种无频差的有功-频率控制算法,即在转子运动方程中,用频率比例积分反馈代替传统的阻尼环节,消除了孤网模式下的频率偏移,同时能够实现微网逆变器的多模式控制。建立系统降阶小信号模型,以系统的稳态性能、动态性能和微网系统相关参数指标为约束条件对所提控制器参数进行优化设计。最后,仿真和实验结果证实了控制算法的有效性和可行性。

Virtual synchronous generator control（VSGC） could overcome impact of traditional grid-connected inverter without inertia to power grid, thus improving ability of grid to accommodate renewable energy, and attracting wide attention in microgrid（MG）. But conventional active power-frequency droop control algorithm was used for VSGC in standalone mode, resulting in permanent frequency deviation, harmful to loads connected to MG system. An improved active power-frequency control algorithm was proposed in this paper, using proportion integration（PI） block to replace damping block in rotor motion equation. It eliminated frequency deviation in standalone mode and enabled MG inverters to realize multi-modal control. Reduced order small signal model was set up to optimize controller parameters based on steady-state and dynamic performances and parameter indexes of MG system. Finally, both simulation and experience results are provided to validate effectiveness and feasibility of the proposed method.