Flywheel Technology Helps Life Spring Eternal for Battery Systems: Running a flywheel energy storage system in parallel with VRLA batteries can lengthen their service life and improve reliability

摘要

Every discharge-recharge cycle reduces the life of a battery. In fact, the higher the percentage of total available energy the battery delivers during a discharge, the greater the reduction in its life. Many batteries used in UPS applications tolerate a relatively low number of discharges before they must be replaced. Furthermore, UPS battery warranties are often tied to the number and duration of discharges as well as the length of time the batteries have been in service. Battery manufacturers know that the frequent discharge of batteries in UPS systems causes them to reach end-of-life long before what would be expected in float service. As a result, they consider the use of batteries in UPS systems as limited cycle service. This is the primary reason why some battery manufacturers require the use of battery cycling monitors to validate warranty coverage in UPS applications. Battery discharges occur for every power disturbance that exceeds the input voltage or frequency limits of the UPS, as well as for most large step-load changes on the UPS output. Thus, the battery's useful life and warranty life can be depleted in a very short period. When flywheel energy storage is used in parallel with the battery, the flywheel provides energy to the UPS during step loads and short-term power disturbances, which greatly increases the useful life of the battery.