Autonomous operation of a MV grid with high penetration of CHP

The increasing penetration of Distributed Generation (DG) units connected to the distribution network, driven mainly by environmental reasons, gives the opportunity to consider islanded operation of electricity distribution grids. Grid disturbances at the transmission level can lead to power interruptions in extended areas. This paper examines the possibility to operate an area with a significant penetration level of Combined Heat and Power plants (CHP) connected to a Medium Voltage (MV) grid autonomously. In this way, a loss of the connection with the High Voltage (HV) grid due preplanned or unplanned events could be survived instead of resulting in an outage. For this purpose the operation of DG units, how these units manage to contribute to the voltage and frequency control during the switch to autonomous operation and how this affects the operational parameters (voltage and frequency) of the network are investigated. Finally it investigates the possibility to reconnect to the HV grid when this has recovered.