Decentralized Secondary Frequency Control in an Optimized Diesel PV Hybrid System

This research aims at investigating if a diesel-based isolated electrical system can be optimized by integrating a high share of solar photovoltaic (PV) generation and if the frequency stability of such system can be improved by including the PV participation in frequency regulation. A case study is developed in order to explore an island’s expansion of the installed generating capacity and its optimization. This study uses the tool HOMER Energy Pro to solve the optimization problem and PowerFactory to verify the frequency stability of the proposed system. The PV integration allows for a reduction of diesel fuel consumption, emissions and generation costs. Additionally, in high PV penetration scenarios, the reduced inertia in such systems can lead to high frequency deviations that may trip the system protection. The study demonstrates that the instantaneous frequency deviation after a load and generation imbalance can be reduced by designing the PVs to operate with an allocated reserve and a decentralized time-based secondary frequency control. The system remained stable under different disturbance scenarios with high PV penetration and reduced available inertia, indicating that high PV integration is economically and technically feasible in a small island system.QC 20200421