Increasing WSCC power system performance with modulation controls on the Intermountain Power Project HVDC system

The interconnected power system in the western US and Canada, designated as the Western Systems Coordinating Council (WSCC), has two DC lines that transmit power for long distances across the system. One of these DC lines, the Intermountain Power Project (IPP) DC transmission system, parallels the east-to-west AC system transmission. The existing AC system has some limitations on power transfers due to power system oscillations at the higher power transfer levels. Utilizing the fast power control available in DC systems, modulation controls on the IPP DC transmission system for improving the performance of the interconnected power system were investigated. It is shown that there is a significant improvement to the performance of the WSCC system when modulation is added to the IPP Southern Transmission System (STS) to damp the 0.7 Hz power oscillations. Adding modulation to the IPP STS has the potential to increase the power transfers or provide additional operating stability between Arizona and California as demonstrated in the 1993-1994 Heavy Winter simulations