IEA Implementing Agreement for International Smart Grid Action Network, a Cooperative Program on Smart Grids (ISGAN) discussion papers are meant as input documents to the global discussion about smart grids. Each is a statement by the author(s) regarding a topic of international interest. They reflect works in progress in the development of smart grids in the different regions of the world. Their aim is not to communicate a final outcome or to advise decision-makers, but rather to lay the ground work for further research and analysis. In this report, SIRFN laboratories (Sandia, AIT, RSE and FREA) establish a harmonized Battery Energy Storage System (BESS) evaluation/certification protocol for advanced energy storage functions. The authors present this standardized protocol as an adoption or revision option for jurisdictions when creating or modifying certification testing requirements. To complete this process, each laboratory shared information on national, international, and jurisdictional grid codes and standards for BESS. Based on these requirements, and BESS testing and certification literature, a broad list of interoperability functions, use cases, storage capabilities, and requirements were compiled. This list was then consolidated to a unique set of BESS functions for inclusion in the certification procedure. Draft certification protocols for five initial functions were created by the SIRFN group in order to harmonize the international effort to establish a unified set of procedures for interoperability testing of BESS.
Improved models of energy storage systems are needed to enable the electric grid’s adaptation to increasing penetration of renewables. This paper develops a generic empirical model of energy storage system performance agnostic of type, chemistry, design or scale. Parameters for this model are calculated using test procedures adapted from the US DOE Protocol for Uniformly Measuring and Expressing the Performance of Energy Storage. We then assess the accuracy of this model for predicting the performance of the TransPower GridSaver – a 1 MW rated lithium-ion battery system that underwent laboratory experimentation and analysis. The developed model predicts a range of energy storage system performance based on the uncertainty of estimated model parameters. Finally, this model can be used to better understand the integration and coordination of energy storage on the electric grid.
As grid energy storage systems become more complex, it grows more difficult to design them for safe operation. This paper first reviews the properties of lithium-ion batteries that can produce hazards in grid scale systems. Then the conventional safety engineering technique Probabilistic Risk Assessment (PRA) is reviewed to identify its limitations in complex systems. To address this gap, new research is presented on the application of Systems-Theoretic Process Analysis (STPA) to a lithium-ion battery based grid energy storage system. STPA is anticipated to fill the gaps recognized in PRA for designing complex systems and hence be more effective or less costly to use during safety engineering. It was observed that STPA is able to capture causal scenarios for accidents not identified using PRA. Additionally, STPA enabled a more rational assessment of uncertainty (all that is not known) thereby promoting a healthy skepticism of design assumptions. We conclude that STPA may indeed be more cost effective than PRA for safety engineering in lithium-ion battery systems. However, further research is needed to determine if this approach actually reduces safety engineering costs in development, or improves industry safety standards.