Resonance Risk in Infirm-interconnected Grid Considering Photovoltaic Devices

Due to the long transmission line and low level of load, the resonance is of severity in the infirm-interconnected grid with power electronic components. This paper uses modal analysis method to analyze the resonance risk of infirm-interconnected grid considering photovoltaic power generation devices (PV). Firstly, the harmonic model of PV, as well as the transmission line, transformer, is established. Meanwhile, in order to reduce the complexity of eigenvalue computation, the harmonic modal impedance of main grid is transformed to that of PCC node connecting the infirm interconnected grid by Gauss elimination. Then a practical infirm interconnected grid in western China is used as the case study and modal analysis is utilized to study the resonance risk. The result indicates that the L-C-L filter of PV would be the main factors affecting the resonance point.