An evaluation of energy storage techniques for improving ride-through capability for sensitive customers on underground networks

Most customers of Consolidated Edison Company of New York, Inc. (Con Edison) are supplied through extensive secondary distribution network systems. These customers do not experience interruptions or outages, except under very rare circumstances. This is a significant advantage for these customers, since they do not normally need to apply conventional uninterruptible power systems (UPSs) for protection of critical loads against outages. However, voltage sags, which occur whenever there is a fault on the power system, can cause dropout or misoperation of sensitive equipment. Some type of protection may be needed for these loads to provide ride-through support during voltage sags. This paper describes the methodology used in a research project sponsored by the Electric Power Research Institute (EPRI) and Con Edison to evaluate the need for voltage sag ride-through improvement for selected customers. Technologies that can supply the required ride-through and application considerations are evaluated. Two case studies are presented to illustrate the methodology used to perform the evaluations.