Featured Projects
Bakun-Sabah AC Interconnection
Egypt-Jordan Interconnection
Emerald Switching Station
Isle of Lewis Wind Farm
Wuskwatim Generating Station


Essex Substation STATCOM


Vermont Electric Power


Vermont, USA
     
 
 
Teshmont provided engineering services for a –60/+120 Mvar STATCOM which was installed at the Vermont Electric Power (VELCO) Essex Substation near Burlington Vermont. The purpose of the project was to provide rapid reactive power supply support to the ac system in the event of unexpected line or generation outages. Such outages could lead to voltage collapse under heavy load conditions. The addition of the STATCOM provided the needed voltage support without the need to run uneconomic generation and will allowed deferment of new transmission additions for at least 10 years.

Teshmont prepared a detailed functional specification for the project, which allowed either a conventional SVC or a STATCOM device to be offered. Teshmont worked with VELCO during the evaluation of bids for the project that included both gate commutated turn-off (GCT) and insulated gate bipolar transistors (IGBT) STATCOM alternatives and conventional SVC alternatives.

The project was awarded to Mitsubishi and consisted of two 37.5 Mvar STATCOM units each with an associated 5 Mvar filter and two 24 Mvar shunt capacitor banks. The STATCOM was the first commercial utility application to use gate commutated turn-off (GCT) thyristors rather than gate turn off (GTO) thyristors. GCT valves have lower losses at low output than GTO based valves, as they do not require snubber components. 		 
 
   

Teshmont provided the following services:

  • Preparation of a functional specification which allowed either a conventional SVC or a STATCOM

  • Bid evaluation

  • Development of ac system equivalent models for use in the contractor’s studies

  • Development of models for the existing Highgate HVDC converter station for use in studying the possible interaction between the STATCOM and the HVDC converter station

  • Design review of the contractor’s electrical and civil designs

  • Witnessing equipment factory tests for specialized equipment including the valves and converter transformers

  • Assisting VELCO with system studies for the project

  • Participating in the factory tests of the STATCOM control systems

  • Assistance with commissioning the STATCOM

  • Review of performance issues and control system optimization to meet the needs of the system