Converter Topology to Integrate Battery Storage with Modular Multilevel Converter

The voltage and frequency stability of the existing AC grid are becoming volatile with the integration of renewable energy based generation. Due to the fitful nature of the power generated by these units, balancing the real/reactive powers and supporting the grid during contingencies has become pivotal. Thus, it compelled to use a system that can help the gridcodes at the Point of Common coupling (PoC) of a renewable power generating unit. This kind of system can be termed as ‘Storage Enabled Statcom (SES)’. A configuration using a Modular Multilevel Converter (MMC) with a battery storage system has been proposed in this paper. The configuration is formed by integrating the low voltage storage modules at the dc-link of the Modular Multilevel Converter (MMC) using a dual-active bridge (DAB). The DAB provides a better conversion ratio and higher efficiency. The effectiveness of the proposed configuration as SES is verified for a grid connected wind power generation system. The proficiency of the proposed configuration for the SES application and the recommended controls has been validated at the PoC of a wind park using the PSCAD/EMTDC platform, and the results are persuasive.