Deploying one DSR per mile per phase can allow operators to increase the line impedance by approximately 2%. The line impedance increase reduces power flow through the line, shifting flow onto other lines with available capacity in the grid. The preliminary results from TVA and SWG's load-flow analysis demonstrate the concept application in meshed networks.
DSRs are self-powered, using line current, and require no more field work than installing them on the targeted lines. The technology is capable of deployment using two-way communications with the installing utility, thus allowing control and contingency support.
Transmission systems are being reconfigured to accommodate the shifting generation landscape. Globally, utilities are seeing a larger range of generation sources and, in many regions, there is a significant redeployment of generation fleets either planned or underway. The magnitude of the problem is significant and expected to grow over the next decade as the generation mix is fundamentally reformulated.
Traditionally, utilities were limited to more expensive methods to address overloaded lines and system capacity constraints. The key to solving transmission system loading constraints in the most cost-effective and coordinated manner is a thorough systems engineering analysis. The final selection of the specific solution technologies is based on a combination of engineering and economic analysis. The choice is a function of the objectives to be achieved, the performance of each solution in attaining the performance specifications and the total costs involved.
TVA expects that DSRs will exhibit many attributes:
Low engineering costs
Low equipment costs
Flexibility — Able to be installed or redeployed quickly to address shifting requirements
Low site costs — Installed on existing transmission lines, no substation engineering or additional substation space requirements
Low balance of plant costs
Fast installation, testing and commissioning
Low ongoing operations and maintenance costs
Easy integration into utility operations, including training.
DSR installations can be engineered, specified and deployed in a matter of weeks. They offer effective power-flow control for the grid and are a cost-effective, simple and reliable alternative to conventional technologies and flexible ac transmission system devices.