Energy storage systems (ESS) have attracted significant interest and investments. Despite this interest, industry and utility engineers have not widely considered this technology as a potential solution to improve the power quality supplied for critical loads. This is in part because of the high cost and in part because of the high complexity to assess this type of solution. This paper, therefore, proposes a practical approach to determine whether shunt/series ESS can mitigate voltage sags assuming the availability of system information, as short-circuit impedance and historical voltage sags, and load information. This is done by analyzing a chart obtained analytically, which can be easily constructed based on simple information from the system and load, without resorting to computer simulations. By inspecting this chart, engineers can quickly determine not only the ESS capacity required to mitigate specific sags, but also which is the optimum power factor for operation. Sensitivity studies are provided to reveal key factors affecting ESS capability to mitigate voltage sags and to validate the proposed approach. Results outline that the requirements of shunt ESS depend on the system short-circuit level and X/R ratio, whereas requirements of series ESS depend on the load demand and power factor.

储能系统（ESS）吸引了大量的兴趣和投资。尽管有这种兴趣，但行业和公用事业工程师尚未广泛考虑将此技术作为改善关键负载供电质量的潜在解决方案。这部分是因为成本高，部分是因为评估这种类型的解决方案非常复杂。因此，本文提出了一种实用的方法来确定并联/串联 ESS 是否可以缓解电压骤降，前提是假设系统信息可用，如短路阻抗和历史电压骤降，以及负载信息。这是通过分析以解析方式获得的图表来完成的，该图表可以根据来自系统和负载的简单信息轻松构建，而无需求助于计算机模拟。通过检查这张图表，工程师不仅可以快速确定缓解特定电压骤降所需的 ESS 容量，还可以快速确定运行的最佳功率因数。提供了敏感性研究，以揭示影响 ESS 减轻电压骤降能力的关键因素，并验证所提出的方法。结果表明，并联 ESS 的要求取决于系统短路水平和X / R比，而串联 ESS 的要求取决于负载需求和功率因数。