同步控制逆变电源并网预同步过程分析

在下垂特性的基础上,通过引入虚拟调速器和虚拟励磁器等概念,赋予了逆变电源频率与电压惯性保持特性,使其动态特性类似于同步发电机。研究了非理想并网合闸条件下,下垂控制同步逆变电源和虚拟同步发电机控制逆变电源并入电网的预同步动态过程。在分析逆变电源并网预同步过程中,为了突出比较两种逆变电源的动态特性,考虑电网的惯量,可以将逆变电源并入同步发电机带负荷系统。在MATLAB/Simulink仿真环境中,对无惯量和有惯量同步电源与微电网在并网动态过程中频率和电压变化进行了对比分析。研究表明,基于下垂控制的同步电源在并网预同步动态过程中,其频率和电压出现突变,变化率较大,而基于虚拟同步发电机控制的逆变电源,其频率和电压不出现突变,具有较平缓的变化幅度。

Analysis of Grid-connecting Pre-synchronized Process for Synchronously Controlled Inverter Power Source

Based on the droop control characteristics, the concept of virtual governor and exciter is introduced to endow the inverter power source with frequency inertia and voltage inertia and dynamic characteristics similar to a synchronous generator. Attention focuses on the research of the grid-connecting pre-synchronized dynamic process of the inverter power sources based on droop control and virtual synchronous generator control in the non-ideal condition. In order to highlight the comparison of external characteristics of two inverters while considering the inertia of the grid, the inverter power source can be annexed to the synchronous generator with a load in the grid-connecting pre-synchronized process. The frequency and voltage dynamic characteristics during the grid-connecting pre-synchronized process of the two power sources above are compared and analyzed with MATLAB/Simulink. Simulation results show that the frequency and voltage of inverter power source based on the droop control changes suddenly and the change rate is large, while the inverter power source based on the virtual synchronous generator has no abrupt change but one that is rather gentle in the grid-connecting pre-synchronized process. This work is supported by National Basic Research Program of China (973 Program) (No. 2013CB228200).