Centralized vs Distributed Wind Power Generation in Microgrids with Energy Storage

The connection of wind power generation (WPG) into ac microgrids (MGs) is steadily increasing. This incorporation can bring problems onto the power quality and dynamics of the electrical grid due to the lack of controllability over the wind and by the type of generation system implemented. This work presents a study of the impact on voltage and frequency of a MG operating in island mode when an important fault occurs. The study is carried out considering different penetration levels of centralized or distributed WPG, and the operation or non-operation of energy storage devices (SDs). For the SDs, a multi-level control scheme is suggested. This scheme includes two control modes of operation of the SD. The first one is used to maintain constant the voltage at the point of common coupling. And the second one is used to contribute to the frequency control when important faults arise in the system. Results show that the models and developed control algorithms of the proposed SDs work satisfactorily. The SD contributes to the recovery of the frequency and enhances the voltage profile when significant disturbances occur in the MG. Therefore, with the SD and control modes proposed, the power quality and the operation security of the MG with high penetration levels of WPG are improved. Moreover, it is observed that the behavior of the frequency is practically the same, either centralized or distributed systems, and a better voltage profile is observed for the distributed system.