Construction, operation and control of a laboratory-scale microgrid

To provide a test facility for possible demonstrations of advanced distributed generation system integration strategies, a single-phase laboratory-scale Microgrid system is set up. Two distributed generators are included in this Microgrid, a photovoltaic simulator and a wind turbine simulator. Both of them are connected to the AC grid via flexible power electronic interface respectively. For stable collaborative operation, a battery energy storage interfaced with a bi-directional inverter is necessary in this Microgrid. In the grid-connected mode, both the distributed generators converters and the bi-directional inverter are the grid-following unit. While switching from grid-connected mode to islanded mode, the bi-directional inverter is setting the voltage and frequency of the Microgrid through absorbing or releasing energy. The operation experimental results show that the laboratory-scale Microgrid system can operate in grid-connected or islanded mode, with a seamless transfer from one mode to the other, and hence increase the reliability of energy supplies.