Transition Management of Microgrids With High Penetration of Renewable Energy

Microgrids are receiving attention due to the increasing need to integrate distributed generations and to ensure power quality and to provide energy surety to critical loads. Some of the main topics concerning microgrids are transients and stability concerns during transitions including intentional and unintentional islanding and reconnection. In this paper, the standard IEEE 34 bus distribution feeder is adapted and managed as a microgrid by adding distributed generations and load profiles. Supervisory power managements have been defined to manage the transitions and to minimize the transients on voltage and frequency. Detailed analyses for islanding, reconnection, and black start are presented for various conditions. The proposed control techniques accept inputs from local measurements and supervisory controls in order to manage the system voltage and frequency. An experimental system has been built which includes three 250 kW inverters emulating natural gas generator, energy storage, and renewable source. The simulation and experimental results are provided which verifies the analytical presentation of the hardware and control algorithms.