System Impacts from Interconnection of Distributed Resources: Current Status and Identification of Needs for Further Development

摘要

Distributed resource (DR) interconnection can contribute to conditions that might go beyond what originally was planned for, designed, and built into the electric grid. A system impact study identifies the electric power system (EPS) impacts that can result if a proposed DR is interconnected without modifications to the area or local EPS. The impact study focuses on potential adverse effects to the operation, safety, and reliability of the area EPS. The decision whether to conduct an engineering system impact review generally lacks a clear, broadly accepted, and strong engineering foundation. Those involved in grid interconnection of DR tend to formulate rules of thumb for impact studies and for establishing their individual preferential resolutions. There are no universally accepted approaches and tools specific to the whole of assessing DR interconnection impacts and resolutions. With the advent of IEEE Standard 1547, modern interconnection equipment has made significant strides by having universal, transparent requirements for interconnection. During grid modernization, however, few changes have been made with the explicit intent to take advantage of accommodating DR to provide benefits to both the DR owner and the grid owner or operator. During these changing times, the grid also is becoming increasingly diverse, and some believe that its existing, site-specific electrical qualities and parameters are less well-known overall. This lack of accommodating DR is not simply a technology issueequipment is available, but the technology needs to be interoperable with other advanced equipment and also with the legacy equipment that makes up the grid, and with grid operations. Further, improved grid operations (e.g., distribution automation) needs to be taken into account. Making the modern grid more robust should include accommodating DR to improve electricity availability for customers, improve grid reliability, and provide additional benefits to both grid operators and their customers. Concurrent with the U.S. Department of Energy research and development (R&D) for grid modernization and with the Energy Independence and Security Act of 2007s smart grid interoperability framework, better approaches, methods, and tools are needed to aid in the consideration of DR interconnected to the grid, for system impact studies, and for resolution that concomitantly promotes and aligns with interoperability and robustness of the U.S. electricity transmission and distribution (T&D) infrastructure. This report documents and evaluates system impacts from the interconnection of distributed resources to T&D systems, including a focus on renewable DR technologies. The report also identifies system impact-resolution approaches and actions, including extensions of existing approaches. Lastly, the report documents the current challenges and examines what is needed to gain a clearer understanding of what to pursue to better avoid or address system impact issues.