Study of direct current bus instability driving by photovoltaic source with constant power load

Abstract

Instability phenomena in Distributed Power System (DPS) usually occur when two or more subsystem combines together. This phenomenon occurs since converter has its internal control function, for example to regulate the converter output voltage. Consequently, the converter tends to draw a constant power which therefore creates negative incremental input impedance within the bandwidth of the converter control which may cause the DC bus instability in a DPS. In this project, a passive damping network has been analysed and designed to overcome the stability problem in a system which consists of a DC source connected to the CPLs via LC filter network. Furthermore, photovoltaic array (PVA) has been modelled as a DC source and extensive study was carried out to investigate its effectiveness in DPS to replace linear DC voltage supply. Passive RC damping network was examined in both DC sources. The system was simulated using MATLAB/Simulink software. The results show that with the help of the passi ve damping, the DC bus voltage more stable when driven by the PVA source compared to linear DC voltage source.