Coordinated Control Design for Reconnection of Islanded Generation

Abstract

In countries with large hydroresources, generation formed by small hydropower plants may have a significant participation in distributed power generation. Small hydropower plants are connected at subtransmission or distribution level and usually are disconnected after contingencies and islanding. Islanded operation requires adequate system dynamics after disconnection and smooth reconnection. The increase in wind generation and photovoltaic sources requires that utilities consider these sources in islanded operation. In this paper, the design of coordinated controllers for reconnection of distributed generation including hydro- and wind power plants after islanding is considered. The design method is based on constrained optimal control, which allows the design of structured controls such as PI, PID and decentralized. The proposed method is applied to a test system with two small hydropower plants and a wind farm. The results show that the proposed method provides a systematic design approach to ensure smooth reconnection of the islanded network to the main network.