Electric Power Systems Security Analysis in Smart Grids with Renewable Energy

External Master ThesisWith the current increase of penetration of distributed energy sources (DES), distribution network operators (DSOs) face new challenges in achieving reliable operation of their networks. One of these challenges is uncontrolled islanding. Uncontrolled live islands may occur when an outage part of a network has online generation for which the DSO has no real-time control or previously established management protocol. In the presence of this issue, the DSO would be forced to implement tight frequency and voltage range in their protection schemes that do are not necessarily compatible with European Network Codes. The purpose of this study is to identify live islands that occur in distribution networks in case of line outages due to contingencies or other reasons. Once live islands are identified, their feasibility is determined by performing a nodal power assessment and calculating for power mismatch, frequency stability and voltage stability. An assessment is made for the best course of action to achieve appropriate conditions for either reconnecting the island or perform a controlled shutdown. This course of action can be complementary steps taken on the demand side (demand response) or generation side (generation response). Previously established protocols along with enhanced communication between the network and the dispatch center will ultimately lead to efficient asset management and improved reliability for the custome