Combined Pre-Synchronization and Power Sharing Control for Microgrid Applications

With the increased penetration of distributed generation in the power distribution systems, it becomes a requirement for microgrids to switch between islanding and grid-connected operation modes. When the line impedance of each micro-source in the microgrid is different, this will cause a mismatch in the output power of the micro-sources. The power mismatch can be overcome in islanded operation by employing power sharing control that provides the power references to the generators. Before connecting to the grid, a pre-synchronization procedure is applied which contradicts with the power-sharing operation as both are controlling generators voltage and frequency to achieve different targets. This paper proposes a control method that combines improved pre-synchronization and power-sharing control that ensures a smooth grid connection and stable operation of the entire system without violating generator power ratings.

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