Project: Plains & Eastern HVDC Clean Line

Service: LCC HVDC, Renewables

Client: Clean Line Energy Partners

Country: USA

Year: 2013 & currently providing on-going support


The Plains & Eastern HVDC Clean Line is a merchant-owned 700 mile 4300 MW three-terminal LCC HVDC transmission line in the USA that is planned to deliver approximately 4300 MW of wind generation in Oklahoma to a 500 MW tap in Arkansas and to a 3500 MW main inverter in Tennessee.

TGS study services:

  • AC Network Reduction— performed using PSS/E
  • Custom PSCAD HVDC Model & Reduced AC system Model Development
  • Custom PSSE Transient Stability HVDC Model Development
  • System Impact Studies — performed using PSS/E
    • Power flow
    • Short circuit
    • Transient stability
  • Detailed Electromagnetic Transient Studies — performed using PSCAD
  • Harmonic Impedance Scans — at each of the HVDC terminals
  • Sub-Synchronous Torsional Interaction (SSTI) Studies

TGS Owner’s Engineer services:

  • Development of the Technical Specification for the HVDC converters
  • On-going technical support during the design phase of the project

TGS Power Quality services:

  • Performed background harmonic measurements for the potential converter locations


One of these challenges with this project was the weakness of the HVDC connection at the rectifier to the AC system. There were ~4500 MW of wind generators connected to a 4300 MW HVDC rectifier, with a very weak connection to the AC system. Numerical stability of the wind generator models in the weak system, combined with a detailed transient stability HVDC model was a challenge that we overcame and learned from. Additionally, the small tap at Arkansas presented a technical challenge to which several possible solutions were presented, including a monopolar tap (instead of bipole), as well as DC controller tuning.