Stability improvement of dc bus in multiple input distributed power system using passive damping circuit

Abstract

Direct current (DC) technologies have drawn more consideration because of the expanding use of (DC) energy sources, energy storages, and loads in power systems. The integration of renewable energy sources into distributed power systems (DPS) usually requires a power converter which can deal with a widely varying input voltage. DPS consist of large complex system build up from many power electronic converters which have internal voltage control process that can regulate the output voltage. Tightly regulated converters, however may cause instability in such systems due to the negative incremental input impedance of constant-power loads (CPLs). Although there is various research for this topic, there still have some limitations regarding on the performance of DPS in term of DC bus voltage fluctuation and damping circuits. In this project, multiple input PV source consists of various series array strings with different (V-I) characteristics distributed power system connected to passive damper circuit was designed and simulated in MATLAB/SIMULINK program. The modelling of passive damper circuit was designed as series (RL), parallel (RL), and (RC) networks and the best performance among the structures was selected. The system is tested to three different values of CPL power which are (2.5, 5, 8 kW) respectively. It was noticed that, the installation of RC damper has shown good results in reducing the CPL effect. Moreover, the effect of combine both damping network and (LC) filter capacitor also discussed. In addition, the selected model was simulated with several filter cut-off frequency and the results were also analysed and explained. Furthermore, the improvement on the performance of the damper was also observed in this project. In conclusion, this project was examined directly the issue in power quality and stability along the distributed power system design and development.