IEEE Power & Energy Magazine - March/April 2016 - 24

Resuscitating Aging HVdc and FACTS Projects

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march/april 2016

It Is hard to ImagIne today's global-scale power grIds
without power electronics technology as it plays such an enormous role in controlling the flow of power and keeping the grid stable. In a world where electric
utilities strive to wring every last watt out of the infrastructure by driving their
systems beyond normal limits, they need the edge this technology gives them.
It's a world where utilities are being urged to increase the capacity of their existing infrastructure efficiently, and power electronics has been helping with that
goal for decades. that's correct, high-voltage dc (hVdc) transmission systems
and flexible ac transmission system (Facts) controllers have been playing a
significant reliability role on the grid for a very long time. so long, in fact, that
many of these electronic wonders have reached the end of their service lives or
are rapidly approaching that point.
like many other pieces of utility electrical apparatus, the design life ranges
from 25 to 30 years for these devices. considering that hVdc schemes have been
deployed on the grid since the 1950s and Facts controllers have been employed
for the past 40 or so years, life extension is becoming an important topic. these
power electronics systems have become so important to their owners and operators that even the passage of time (i.e., aging) cannot be tolerated. consequently,
every effort is being made to keep them operational and functioning as long as
possible. this has become extremely challenging as manufacturers merge or are
no longer in business and the workforce is retiring, with their knowledge base
being lost faster than it can be captured.
of course, the simplest approach would be to replace the entire facility when
the device reaches a specific chronological point in time. but it isn't that easy,
and there are several governing factors that must be considered. these devices
are made up of many subassemblies (for example, thyristors valves, control systems, cooling equipment, and transformers), each with its own service life, which
can vary considerably. replacing the entire system would consign valuable components to a landfill or a metal scrapper's recycling program, costing the utility
a great deal of money that could be better spent on other projects (see Figure 1).
refurbishment of the hVdc or Facts installations offers several advantages
over total replacement. one of the most significant is the much lower costs associated with refurbishment. only the subsystems that have reached the end of
their service life are replaced, allowing long-lived components to continue functioning. there is also the reduction in the construction time frame, transmission
system disruptions are minimized when compared to replacement of the entire
facility, and permits are usually not required.

Refurbishment Is Born
It is important to keep in mind that refurbishment is more than just replacing
components. It is the act of renovation, restoration, overhauling, revamping, or
Digital Object Identifier 10.1109/MPE.2015.2501059
Date of publication: 18 February 2016

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