Study on Water Saving Technology for External Cooling System of HVDC Converter Station Equipments

The study focuses on the water saving technology for external cooling system of DC transmission converter station equipment, a water saving design applicable to external cooling system of such key equipment cooled by water as converter valve and transformer in the converter station of the conventional/flexible DC transmission project. Current external cooling method for converter valve equipment in the converter station mostly combines the closed-circuit cooling tower and spray cooling. This method, however, has the disadvantages of, for example, high water consumption and large quantity of blowdown. In view of this, this paper proposes a water saving technology by sewage recycling through spray treatment system based on two-stage reverse osmosis. In this technology, the water in the converter station can be recycled, thus achieving the purpose of water saving and blowdown reduction. For the transformer cooled by external cooling with water, this paper provides an optimized design of common configuration in which the external cooling systems of converter valve and transformer share the same spray pool and spray treatment equipment. This design will not only save water resources, but also facilitate the operation, maintenance and comprehensive management of converter station. It is thus in accord with the green development philosophy of converter station.