Lamar - Back-to-Back Converter Station

The Lamar HVDC project is an important high-voltage direct current (HVDC) transmission system located in Lamar, Colorado. It consists of a back-to-back HVDC converter station that interconnects the Eastern and Western power grids of the United States.

Technical Specifications

The Lamar HVDC link has a power rating of 210 MW continuous capacity. It operates at a DC voltage level of 63.6 kV and connects AC systems at 230 kV (West Lamar/Colorado) and 345 kV (East Finney/Kansas), both at 60 Hz frequency. The converter uses direct-light-triggered thyristors rated at 8 kV.

Design and Construction

The Lamar HVDC project employs an innovative grounding concept for the DC circuit, allowing the use of standard distribution transformers instead of specialized HVDC converter transformers. This design choice results in shorter delivery times and enables higher local manufacturing content, contributing to cost efficiency.

Engineering specifications, procurement, and project management for the Lamar project were performed from Xcel Energy's Denver office. The project has been in commercial operation since January 2005.

Grid Integration and Control

The Lamar HVDC link plays an important role in controlling voltage at the Lamar 230 kV bus. It operates alongside wind generators in the area, such as the Colorado Green wind farm. To prevent control conflicts, a delay/droop mechanism is installed on the wind farm controls.

The project includes subsynchronous resonance (SSR) controls, although the full extent of their interaction with nearby wind farms could not be analyzed due to limitations in wind turbine models.

System Impact and Benefits

The Lamar HVDC link enhances the flexibility and reliability of the regional power grid. It allows for power flow control between the Eastern and Western Interconnections, facilitating energy transfers and improving system stability.

Integration with Regional Markets

The Lamar HVDC link is integrated into regional electricity markets. It participates in the Western Energy Imbalance Market (EIM) and is expected to be part of the proposed Extended Day-Ahead Market (EDAM). These market structures allow for full co-optimization of the HVDC line's dispatch between participating balancing authorities, maximizing its economic and operational benefits.