Battery Chemistry Agnostic Grid-Tied Secondary Use Energy Storage System

M. Chinthavali, M. Starke, S. Marti, R. Krishnamoorthy, P. Bhowmik
Oak Ridge National Laboratory,
United States

Keywords: power electronics, secondary use


As more and more renewable energy resources, energy storage systems, and loads are being adopted, more grid-connected power conversion systems are being introduced into buildings, too. Some of the components used in these systems are redundant increasing the cost of the equipment and reducing the efficiency. These loads and sources are not typically from the same company or use the same communication protocols, which make it difficult for an energy management system to efficiently manage the building power demand and generation. The concept proposed here solves all these issues and introduces a scalar, modular, and efficient power electronics hardware system. Today, each inverter company builds inverters typically for one application. This approach does not allow integration inverters for different applications using some common components to save cost. Each battery source and load require a different power conversion system, which results in redundancy, complex coordination, and reduced energy conversion efficiency. This can be solved with a centralized solution that allows coordinated integration of different battery sources and loads, elimination of extra power conversion stages. In this project the overall goal is to reduce the balance of systems costs associated with grid-tied energy storage systems by making systems modular and with a simple plug and play feature. For this proposed concept, a modular and scalable power electronics interface was designed to integrate various battery sources with different chemistries to ac and dc loads efficiently with reduced power conversion stages. This is a novel method of integrating batteries and power electronics to provide efficient coupling between the two for improved power conversion. ORNL has designed a multi-port modular power electronics interface for a grid-tied energy storage system. The system includes 25-kW modular dc-dc converters and a dc-ac inverter for 480 V grid system. The energy storage system also includes a software interface that hosts the algorithms and the overall control scheme which integrates the functionality of the multi-port power electronics hardware unit. This includes the different battery systems integrated into a single battery system.