Impacts of battery energy storage system on power grid smartness: Case study of Taiwan Power Company

This case study work aims to quantitatively validate the hypothesis that battery energy storage system (BESS) can enhance the smartness of power grid. Our targeted power grid was the Taiwan Power Company (Taipower), which ranked second worldwide in both 2021 and 2022 according to the Smart Grid Index (SGI), a global grid smartness indicator. Besides collecting data from Taipower, this study examined 53 upstream and downstream energy storage companies and 48 ancillary service companies in Taiwan. Through cross-domain data analysis, the evidences were obtained to verify the hypothesis. The initial piece of evidence suggests that BESS is a key evaluation indicator for determining the smartness of a power grid. Of the 36 and 38 power utilities in 2021 and 2022, 77.8–80 % of power utilities with high smartness scores were equipped with energy storage systems, compared to only 14.3–15 % of power utilities with low scores. Further evidence indicates that the data on two power failure events indicate BESS can prevent power grid accidents. Thus, the supply reliability can be improved. Estimated data shows that annual SAIDI index scores dropped from 14.936 to 11.978 and SAIFI index scores dropped from 0.185 to 0.151 after the implementation of BESS. The third piece of quantitative evidence is that data on grid-level BESS construction achievements shows that SGI scores increased from 28.0 to 94.6 over five years, moving from a ranking lower than the global average to rank second in the world. In addition to verify the hypothesis, the aforementioned evidences also lead to novel results. This case study is pioneering in its first-time analysis of state grid data and the organization of items of smartness within global girds, resulting in a proposed flowchart for constructing a smart grid. The establishment of the flowchart will contribute to enhancing the smartness of power grids through the design of ancillary services.