doi:10.3850/978-981-08-6396-8_P077

ABSTRACT

An underground 66kV electrical substation (ESS) has been planned on the Singapore Downtown Line (DTL) Mass Rapid Transit (MRT) system project. The ESS, along with the other substations, provides power to the entire DTL. The ESS will be the first substation of its kind in Singapore to be located entirely underground to facilitate better use of land while providing good integration with the surrounding environment. There will be four 66kV/22 kV transformers housed in individual rooms in the ESS. Each transformer is estimated to dissipate up to 330kW of heat when operating at transformer full load condition.

The transformer rooms were initially designed to be mechanically ventilated. Large mechanical ventilation plants were provided to deliver large quantities of air to the rooms to keep the room temperature within acceptable limit for optimal performance of the transformers. Due to concern with high operation and maintenance costs associated with the mechanical ventilation system, natural ventilation was adopted for better energy efficiency and sustainability. For the natural ventilation design, buoyancy effects of hot air, and unique features of the rooms, such as high ceiling and large volume, were exploited. Critical factors such as ventilation louvre arrangement, and separation of intake and exhaust air paths within the rooms were also taken into consideration.

Fluent Version 6.3 was used to perform three dimensional computational fluid dynamics (CFD) simulations to evaluate the effectiveness of the transformer room natural ventilation design. Various operating conditions such as different transformer loading conditions, and outdoor air temperatures, were examined. This paper presents the natural ventilation design of the transformer rooms, and CFD results on the air temperature and velocity profiles within the rooms.

Keywords: Natural ventilation, Underground, Electrical substation.

© 2010 WUTC Organisers