Detection of Islanding Feasibility in Subtransmission Systems

The penetration of Renewable Energy Sources (RES) is increasing in modern power systems. The integration of large amounts of RES is a challenge but the technology provides many tools to exploit them for uses and functions considered, so far, a prerogative of more traditional power plants. For example, since a large amount of RES is installed in HV subtransmission grids, it is possible to exploit them in wanted and unwanted islanding conditions. In this paper, a procedure for evaluating off-line the feasibility of islanded operation and planning it is presented. This procedure defines which generators and loads could remain connected after islanding to balance the real power of the island. For each possible set of islanding events, the set of discrete control actions (opening switches) is determined and communicated to local Substation Automation Systems, to be put in place in case of actual islanding. Results, including dynamic simulation responses, are shown with reference to real power systems.