直流逆变分布式电源降阶模型及小扰动稳定分析

分布式电源类型及控制方式多样,致使含多种分布式电源的小扰动机电暂态分析的电网模型复杂,分析难度加大.针对应用较广的光伏和燃料电池两种分布式电源,在对其全阶状态空间模型的特征分析和电池动特性时间尺度分析的基础上,提出了前馈解耦控制下考虑电池U-I外特性和逆变控制系统动特性的光伏发电系统降阶模型和忽略逆变系统快动态特性的燃料电池降阶模型,并应用于4机2区域系统并网小扰动分析.研究结果表明:直流DG并网主要通过改变系统潮流及平衡点影响系统阻尼特性;直流DG出力增加时,与采用降低出力增加旋转备用运行方式的常规机组强相关的模式阻尼特性会呈现增大的趋势.

The Small Signal Stability Analysis of the Grid Connected DC Distributed Generation with Reduced Order Model

Compared with the traditional power, many different kinds of micro sources and control modes are used in distributed generation (DG) , which makes the small signal electromechanical transient analysis of the power grid difficult. This study established a reduced order model of photovoltaic (PV) power generation considering the behavior of battery and inverter, and presented a power source model of solid-oxide fuel cell (SOFC) by analyzing the characteristic patterns of the full-order state-space model and the time constant of SOFC and PV. Then, the model was used to study the effect of grid-connected DC distributed generation on power system small signal stability through simulation examples. The research shows that SOFC or PV affects the system damping characteristics by changing the power flow and the system equilibrium point. When the output increases, due to the increasing spinning reserve of the conventional unit, the damping characteristics are strongly related to the conventional unit, in which working in the operation mode of reducing output will show a tendency to increase.