Playing a major role
Electricity of Vietnam (EVN) is a state-owned facility charged with generating, transmitting and distributing power throughout Vietnam. It is spearheading the national government’s effort to boost the total installed generating capacity in Vietnam to 53 GW by 2020.
The Son La hydropower plant, located on the Da River about 340 km northwest of Hanoi, is a critical part of that effort. However, the timeframe for building it – three years from contract signing to Unit 1 power generation – was challenging for a project of this scope, so moving rapidly was necessary.
Significant technical and economic advantages
GE installed six 400 MW Francis hydro turbine- generator units, and provided plant engineering and auxiliary balance-of-plant components.
Since the turbine’s thrust bearing configuration in Son La is supported by the turbine head cover, it has a shorter shaft line that helps reduce manufacturing and civil works costs, and a more rigid head cover for improved axial dynamic behavior. The design also eliminates direct transmission of axial hydraulic loads to the concrete structure, and has the thrust load balance the pressure load under the turbine, which reduces head cover deformations.
Associated membrane technology ensures that each pad has a self-equalized load and that the load is always properly distributed between the pads.
The composite material coating the thrust bearing pads has much better load carrying, dimensional integrity and thermal resistance than white metal pads, so there has been less wear and reduced bearing loss, as well as improved safety in running conditions.
Strong, flexible oblique elements that simultaneously withstand radial and tangential forces allowed the frame to absorb torsion along the minimal resistance direction when the core expands. The resulting improvement in frame hot stresses and stator capacity for free, concentric and even expansion in a radial direction will increase the lifetime and secure the safety of the generator.
A huge annual output
The 2,400 MW Son La plant, which was completed ahead of schedule in 2012, can generate up to 10 billion kWh per year, making it the biggest hydropower plant in Southeast Asia. Resourceful actions were applied to help beat the deadline: Six stay ring and spiral case units were applied in advance of the contract-stipulated date, and weather-related transportation obstacles were worked around by completing fabrication in two months with round-the-clock work.