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

由于中央发电厂的负面环境影响和低效率，可再生分布式发电（DG）系统在电网系统中激增。 可再生DG可以包括太阳能、燃料电池、风能或其他可再生能源。 可再生DG的设计者和用户面临的一个主要问题是这些能源的随机性和波动性。由于这种系统是间歇性的，并且容易出现稳定性问题，因此存储的使用变得至关重要，并且将存储集成到DG系统中已成为主流。美国的“储能2013法案”等税收激励措施、德国对储能系统的补贴、美国军队最近的投资以及欧洲和加拿大几个合作伙伴财团最近启动的项目都是证明储能系统重要性的几个例子。因此，设计和实施包括储能选项的新型电力电子系统（PES）在未来几十年将至关重要。PES旨在从可再生DG中提取电力并将其提供给负载和电网。然而，大多数现有的PES仅在存在带电电网时运行，称为并网运行模式。这种系统通常不支持在停电时向负载供电，称为孤岛操作模式。支持两种操作模式的PES通常需要能量存储设备，并且通常是定制设计的，具有更大的复杂性。对于光伏（PV）系统，支持两种模式的现有PES主要被设计为“中央”配置，其中所有PES接口和控制系统被设计在一个设备中。然而，中央PES表现出严重的缺点，如在部分遮光条件下能量收集差。因此，最近的研究集中在“分布式”PES的发展，如微型逆变器和模块集成转换器。在分布式PES中，每个模块或电池具有指定的PES以最大化能量收集。分布式PES，由于许多理论和实践的挑战，尚未被研究和设计为孤岛模式的操作。开发一种新的分布式PES配置，具有可选的能量存储，最大限度地提高效率并最大限度地降低生产和安装成本，这是该提案的总体愿景。新的体系结构具有中央和传统分布式PES的优点，并增加了简单性、廉价的可扩展性、支持两种操作模式和耐用性等功能。拟议的研究有可能导致为每个用户提供许多好处的技术，在偏远地区，电网系统薄弱或不可靠，以及有或没有关键负载的电网连接。该研究的独特性质是根据需要和负担能力逐步扩大该系统。这特别有利于贫穷国家或预算有限的人。与现有的可再生DG系统不同，在大规模住宅应用中使用该技术不仅利用可再生PES作为不间断电源，而且还有助于智能电网概念的发展。这是通过频率调节、峰值时间需求响应、无功功率补偿以及谐波和骤降/浪涌补偿来帮助平衡电网来实现的。此外，该技术可以被偏远社区、具有有限的公用设施连接时间的郊区、设备站、任何移动的单元（诸如专用车辆或军事单位）、电信和紧急避难所采用。

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.