Woojin Industrial Systems, a leading manufacturer of electric rail vehicles and rail system equipment, has completed installation of its energy storage system (ESS) ultracapacitor-based braking energy recuperation systems in seven Metro stations in Seoul, Daejon, Incheon and the Korea Train eXpress (KTX) high-speed rail depot in Seoul.
Beginning with installation of demonstration systems in 2009 under a contract with the Korean federal government’s Korean Railroad Research Institute (KRRI), Woojin and rail system operators have achieved grid power consumption savings of more than 20 percent and realized additional benefits in the form of system voltage stabilization that reduces power infrastructure requirements and helps to ensure uninterrupted operation. The recuperation systems, ranging from 750 to 1,500 volts, employ Maxwell ultracapacitorsUnconventional internal design yields a larger capacitanceThat property of a system of conductors and dielectrics which permits the storage of electricity when potential difference exists between the conductors. Its value is expressed as the ratio of a quantity of electricity to a potential difference. A capacitance value is always positive. per unit volume than other types. Valuable for high-current and low frequencyThe number of complete cycles or vibrations per unit of time. Rate of alternation in an AC current. Expressed in cycles per second or hertz (Hz). electrical circuits, power supply filters, etc. Applications are similar to those of rechargeable batteries. to absorb energy during rail vehicle braking and deliver the stored energy to the vehicles’ electric motors for propulsion and to stabilize voltage throughout the system.
Each installation employs up to 200 of Maxwell’s 48-volt multi-cell ultracapacitor modules. Based on their positive experience to date, Woojin and rail system operators are planning several additional installations in 2014 and 2015.