Vol. 2, Issue 7, Part N (2016)

Abstract
It is necessary to briefly review the current operation practice on western Oregon subsystem in Pacific Northwest before introducing the slow voltage controller framework. This part of system is a large load area without significant local 43 generation. Power is imported from other parts of Pacific Northwest and western Canada. There are tens of small capacitor/reactor banks and LTC transformers available for voltage control purpose in this area. During normal operation, voltage problems are alleviated by reactive compensation performed by system operators based on their experience, current and predicted network conditions. Switching out in-service devices is preferable than switching in alternate devices such that the maximum number of devices are available for future exercises. Tap changing has lower priority than reactive power compensation switching and tap changing frequency is restricted to several tap changes per day because tap changer failure results in transformer outage. Circular VAR flows are monitored by routinely checking the VAR flows on specific transformer banks and transmission paths and are mitigated by switching of capacitor banks or transformer tap changer settings.