Synchronous generator-based grid-interface converter for energy storage systems integration

The common, and with some exceptions the only method to interconnect high power renewable energy sources and energy storage systems to the grid has been using power electronics converters that operate as current sources to the grid for the purpose of achieving the maximum primary-source power tracking. When grid is not available, such sources would not be allowed to continue operating and will be shut-down after anti-islanded algorithms recognize the loss of the grid. Although existing standards and requirements still limit grid-interface converters to regulate voltage in the grid, this functionality will inevitably be the part of the power system operation in the future. This paper addresses physical and mathematical equivalency between power electronics converters and synchronous generators, and emphasizes how an inherent synchronization feature of the synchronous generators can be used to improve the performance of the grid-interface converters. It has also been shown that if operated as a voltage source, grid-interface converter could have significant stabilizing effect on the system dynamics due to the non-delayed power delivery.