SVC for reliability improvement in the NSTAR 115 kV cape cod transmission system

NSTAR Electric Company is operating an ABB SVC on its 115 kV transmission system in Massachusetts, to supply fast-acting voltage support to the transmission system on Cape Cod in the event of loss of two major transmission lines. The system is fully automated to activate and inject reactive power when the transmission system voltage falls below a specified set point. A large part of the area load consists of induction motor loads. A goal of the SVC is to help re-accelerate motor loads after grid faults. The paper describes the transmission system characteristics leading to the decision to invest in SVC. Secondly, it highlights the SVC, as well as offers a few words on RTDS studies to confirm the functionality of the SVC. Thirdly, some operating experiences of the SVC are given demonstrating the usefulness of the SVC under normal operating conditions.