Carnegie Mellon Electricity Industry Center

2002-03 Seminars

Recent Developments in Electric Power Transmission Technology

Dr. Kalyan K. Sen
Fellow Engineer at Curtiss-Wright Electro-Mechanical Corporation and IEEE
Distinguished Lecturer

Abstract

With the transmission lines becoming loaded to their capacity and new lines
being hard to site and build, the ever-growing need for transporting more
electricity can be met either by installing new transmission lines or by
using the existing ones in a more efficient way. The latter approach is to
maximize the active power flow that generates revenue while minimizing the
reactive power flow that only heats up the line and contributes nothing to
the useful energy delivered. Traditional solutions, such as the shunt
compensator, the series compensator, and the phase-shifting transformer
affect both the active and the reactive power flow in the transmission line
simultaneously. With the use of a Unified Power Flow Controller (UPFC),
which is based on Voltage-Sourced Converter (VSC) technology, the active and
the reactive power flow in the line can be regulated independently. All
VSC-based Flexible Alternating Current Transmission Systems (FACTS)
controllers have two major drawbacks. These are their high installation and
operating costs. In order to address these two issues, a new concept in
FACTS controller is proposed. The new concept is more reliable, more
cost-effective, and based on proven technology of transformers and load tap
changers. The Sen Transformer (ST) is a new family of power flow
controlling transformers that provides the same independent active and
reactive power flow control as the UPFC, but with a 5:1 reduction in
equipment cost and 10:1 improvement in operational cost.