基于暂态分析和系统辨识的光伏并网逆变器建模

建立并网光伏发电系统的模型是研究其与电网交互过程的基础.光伏系统的暂态特性不仅受天气情况、电网工况等环境因素的影响,还取决于商用逆变器的内部结构以及控制策略,然而它们并不对外公开,这给系统的分析带来了困难.为了解决这个问题,该文提出一种基于暂态分析和系统辨识的光伏并网逆变器通用建模方法.将光伏逆变器视作内部结构以及控制算法未知的黑箱,通过先后施加扰动和测取响应并结合系统辨识的方法来建立其模型.以一个3kW的商用光伏逆变器为研究对象,搭建硬件在环实验系统来研究并验证这一建模方法.结果显示,在多种扰动对应的暂态过程中,模型的输出均准确地拟合了逆变器的实际输出,证明了这一建模方法的有效性.

Modelling of Commercial Grid-Connected PV Inverters Based on Transient Analysis and System Identification

The modelling of grid-connected photovoltaic (PV) generation systems is the basis for studying their interaction with the grid. The transients of PV systems are determined by weather and grid conditions, as well as the characteristics of commercial inverters, whose topology and control algorithm are usually unknown. This hinders the analysis of the impacts that PV systems might have on the grid. For this purpose, a generic process for modelling PV systems based on transient analysis and system identification is presented. By viewing a PV system as a black-box without knowledge of its internal components, structure or control algorithm, the model was established through measured input-output data and system identification. Transfer functions were taken as the model structure based on classic control theories. A power hardware-in-the-loop system was used to verify the process by collecting instantaneous input-output data from the terminals of a commercial 3kW PV inverter. The results show that the developed model reproduces accurately the transients of the inverter under various disturbances, demonstrating the effectiveness of this generic modelling process.