The Electric Power Research Institute (EPRI) research in 2011 explored the potential use of battery storage to increase transmission capability in thermal limited transmission paths, an application of energy storage technology that has not been investigated in detail in prior research (see EPRI report 1024586). Researchers performed a conceptual analysis of how batteries connected at either the sending or the receiving end of a congested corridor can be used to increase the transmission capability of the corridor by reducing overload under contingency conditions. A case study on a generic power system model was conducted to further illustrate the concept, including an economic analysis of benefits and costs. An attractive benefit-to-cost ratio from that analysis indicated that further analyses would be justified.
The prior work indicated that research to fully assess the convenience of batteries to deal with thermal overloads, comparing performance and cost with other options, should be performed. Additionally, the use of a battery system for other purposes, providing further benefits to offset the capital cost of the project, should be investigated. For example, a battery can be located at a congestion point to primarily provide support under contingency. Since the battery is charged or discharged only occasionally for contingency mitigation (providing overload relief and/or voltage support), at other times it could be used for other purposes such as contingent reserve power, peak price sales, and other market functions. A battery can also be used during or after a wide-area outage for transmission support under contingency and for system restoration (black start).
The objective for the present effort is to analyze the possibility of using the same battery installation for multiple purposes including circuit overload relief, voltage control, stability improvement, and black start support. The results are reported in this technical update. Research in 2013 is expected to include a comprehensive cost study to assess investment as well as the operation and maintenance cost of batteries for different applications, followed by a full case study on an actual power system.