Distributed High Power Density Converters for Renewable Energy Resources with Optional Energy Storage Systems

点击翻译按钮获取中文摘要

Due to negative environmental impacts and inefficiency of central power plants, renewable distributed generation (DG) systems have proliferated in electrical grid systems. Renewable DGs may include solar, fuel cells, wind, or other renewable energy sources. A major issue confronting designers and users of renewable DGs is the random, fluctuating nature of these energy resources. As such systems are intermittent and prone to stability issues, the use of storage has become crucial and the integration of storage into DG systems has become the mainstream. Tax incentives such as "Storage 2013 Act" in the states, subsidies on energy storage systems in Germany, recent investments by U.S. army, and launching of recent projects by consortium of several partners in Europe and Canada are a few examples that attest to the importance of energy storage systems. Therefore, design and implementation of new power electronic systems (PES) that include energy storage option will be vital in the coming decades.**PESs are designed to extract power from renewable DGs and provide it to loads and electrical grids. However, most of the existing PESs operate only when the live grid exist, known as grid connected mode of operation. Such systems normally do not support supplying power to loads when there is a power outage, known as islanded mode of operation. PESs, supporting both modes of operations, typically require energy storage devices, and are usually custom designed with much more complexity. For photovoltaic (PV) systems, existing PESs that support both modes are mainly designed in "central" configurations where all the PES interface and control systems are designed in one device. Central PESs, however, have exhibited serious shortcomings such as poor energy harvesting in partial shading conditions. Consequently, recent research is focused on the development of "distributed" PESs such as microinverters and module integrated converters. In distributed PESs, each module or cell has a designated PES to maximize energy harvesting. Distributed PESs, due to many theoretical and practical challenges, have not yet been studied and designed for islanded mode of operation. Developing a new distributed PES configuration, with optional energy storage that maximize efficiency and minimize production and installation costs is the general vision of this proposal. The new architecture has both advantages of central and traditional distributed PESs, and adds features such as simplicity, inexpensive scalability, support of both modes of operation, and durability.**The proposed research has the potential to lead to technologies that offer many benefits to every users, with weak or unreliable grid systems, in remote areas, and grid-connected with or without critical loads. The unique character of the research features gradual expansion of the system proportional to the need and affordability. This is specifically beneficial to poor countries or people with limited budgets. Unlike existing renewable DG systems, the use of this technology in large scale residential applications not only exploits the renewable PESs as an uninterruptable power supply, but also contributes to the development of smart grid concept. This is achieved by helping balance the grid through frequency regulation, peak time demand response, reactive power compensation, and harmonic and sag/swell compensation. Furthermore, this technology can be employed by remote communities, suburban areas with limited utility connection time, equipment stations, any mobile units such as special purpose vehicles or military units, telecommunications, and emergency shelters.