Polarconsult Alaska Inc.: High Voltage Direct Current Transmission - An Emerging Energy Technology Grant Project
The Polarconsult Small-Scale High Voltage Direct Current (HVDC) project seeks to design, develop, and demonstrate 1) small-scale HVDC converters and 2) innovative complementary transmission infrastructure with the goal of reducing costs for applications in rural Alaska.
Polarconsult Alaska, LLC is a civil engineering firm based in Anchorage, Alaska and the champion for this project. The project is made up of three phases; Phase 1 and 2 were funded by the Denali Commission with the Alaska Center for Energy and Power (ACEP) providing grant management and lessons learned reporting for Phase 2. Phase 2 is the subject of this report.
Lowering the cost of power transmission via HVDC has been suggested as an option to reduce and stabilize the cost of delivering power to Alaska’s rural villages. Power in most villages is provided by diesel powerhouses; the high and volatile price of diesel often means significant economic hardships for those communities. Transmission by Alternating Current (AC) is limited by high costs, and line losses that increase with transmission distance. Direct Current (DC) transmission, in contrast, has fewer infrastructure requirements and lower line losses, and can be economical over long distances. However, existing HVDC technology for the scale of electrical demand of rural villages, typically less than 1 MW, is not available. Therefore, the development of small-scale HVDC systems, power converters, and multi-terminal networks, are of critical need if HVDC technology is to be applied in rural Alaska.
Phase 1 of this project included a feasibility analysis of the proposed HVDC system and construction and testing of a prototype 250 kW 12.5 kV HVDC converter to confirm that the technology met key performance benchmarks. Phase 1 was completed in 2009. Given the successful completion of Phase 1, the Denali Commission approved funding for Phase 2 of the project.
The goals of Phase 2 were to complete full-scale prototyping, construction, and testing of the HVDC converters and transmission system hardware. The end goal was to finalize system designs and construction techniques, and verify construction costs.
Princeton Power Systems (PPS) was selected by Polarconsult to develop, construct, and test prototype-scale converter units suitable for eventual field demonstration in Alaska. Working with key project stakeholders, Polarconsult specified a 1 MVA converter for a 50 kV DC transmission system, consisting of two 500 kVA modules. These units were designed, constructed, and tested at PPS’s facility in New Jersey. In addition, Polarconsult focused on additional transmission infrastructure cost-reduction potential for using HVDC. This culminated in the construction and field testing of an innovative transmission pole design in Fairbanks, Alaska.
During Phase II, a 1 MVA converter for a 50 kV DC transmission system, consisting of two 500 kVA modules, was designed, constructed, and tested. While the project demonstrated the technical feasibility of the converter, several critical hardware issues arose during testing that need to be addressed before further demonstration can occur. Once a fully functional prototype is developed, independent testing of the converters will still be needed to validate efficiency and performance.
Polarconsult conducted a field demonstration of a system composed of a glass fiber-reinforced polymer (GFRP) pole, micro-thermopile pole foundations, micro-thermopile guy anchors, and screw guy anchors. This demonstration successfully displayed a potentially viable alternative approach to developing transmission in Alaska by designing “up” based on location rather than just modifying current industry practice. However, there were concerns identified with the demonstration that limit the ability to assess the demonstrated system, and make recommendations regarding the design, performance, and functionality.
From this demonstration, it is recommended that before further project activities commence, design and performance standards for the envisioned converter technology be formally codified by professional stakeholders. Such standards could include target operating conditions, operations and maintenance requirements, integration and controls functionality, and even materials characterization. It is also recommended that further development of an Alaska-specific design approach to transmission be conducted as a separate activity from the development of small-scale HVDC converters. Significant work remains in terms of developing and demonstrating this approach as a technology that is commercially ready and without significant risks for an Alaskan utility or operator.
There is an additional concept phase to the Polarconsult HVDC project, Phase 3, which seeks to demonstrate the converter technology developed and refined through Phases 1 and 2 in the field. A prototype will need to be deployed on an Alaskan utility system to validate its functionality and reliability in a commercial setting. The field test will also provide an opportunity to observe and meet the nontechnical challenges that exist to deployment in Alaska. Polarconsult is currently seeking funding to execute this phase.
Photo 1: PPS High Voltage Converter Unit Open and Undergoing Inspection. Courtesy Jason Meyer, ACEP.
Photo 2: PPS HVDC System Testing. Courtesy Jason Meyer, ACEP.
Photo 3: PPS High Voltage Converter Unit. Courtesy Jason Meyer, ACEP.