CONNECTING HYDROPOWER TO THE GRID IN SOLOMON ISLANDS
Client: Solomon Power
Location: Honiara, Solomon Islands
Date: Jan 2017 – June 2020
Feasibility studies and detailed design of a 66 kV transmission line from the Tina River hydropower project to the Honiara power grid
Background
The Tina River hydropower plant is set to be the first large utility-scale renewable energy project for the Pacific Island nation of Solomon Islands. It will generate 15 MW of clean energy and meet more than 80% of Honiara’s electricity needs once operational.
Entura has been involved with the project for over a decade, conducting pre-feasibility and full feasibility studies. We were engaged to investigate the options for a 66 kV transmission line for the integration of the project to the Honiara network in 2017, followed by its design in 2020.
The resulting proposal is for two 23 km single-circuit lines from Tina Hydro to Lunga Power Station, traversing hilly terrain and several rivers. The 66 kV line route has to share easement with existing and planned roads as well as a proposed 11 kV feeder.
The project was challenged by difficult survey terrain and the COVID-19 pandemic, which restricted travel to the site.
Solution
Entura was engaged to conduct a feasibility study of four potential options for a 66 kV transmission line connecting the Tina River hydropower plant to the Honiara network.
There were multiple challenges to completing the feasibility studies, including an expansive survey area of 84 km across 11 route sections, a challenging site with difficult terrain and a limited timeframe.
To overcome these, we conducted an aerial survey using LiDAR technology to capture ground points and orthophotos. This information was used to create a 3D model of the terrain and perform optimised route selection and pole spotting studies, allowing us to test each potential route in a shorter timeframe and determine the best solution.
After exploring several iterations, Entura worked closely with the client to coordinate the locations of both the 66 kV and 11 kV poles as well as the proposed road. Four different types of concrete-encased direct buried steel poles with two height options each were proposed to support a single-circuit line with optical ground wire from Tina Hydro to Lunga Power Station.
Entura’s technical support to the client will continue during the build, developing pole specifications and load trees to form part of the technical specifications for construction. We will also prepare foundation designs based on calculated foundation reactions and geotechnical parameters based on site investigations.
Services provided
- route selection and optimisation
- optimum pole spotting and line design
- pole specifications and loading trees
- foundation design
- technical support during construction
Outcome
Entura was able to determine the optimal path for the 66 kV transmission line by using innovative LiDAR modelling and problem solving. Exploring and assessing several options coordinated with other infrastructure within the proposed corridor required a number of iterations that are only possible by having an accurate 3D model.
Despite COVID-19, we maintained a close working relationship with the client during the design phase, using available communication technologies to reduce travel to site.
Our adaptability has enabled us to provide the client with a preferred design, which we will continue to support through the construction phase.
