IEEE Power & Energy Magazine - March/April 2016 - 47

of 430 MW. it came online in 1985, bringing the total HVdc
transfer capability in each direction between the two provinces to 780 MW. the thyristor valves are air cooled, and
they have experienced many deficiencies in the past years,
with no spare parts available. C&p failures have also significantly increased, but until recently, redundant control
systems helped prevent a complete outage.
a refurbishment project is ongoing, and commissioning is
foreseen by the end of 2016. a six-month outage is being estimated for the complete work. it consists of replacing thyristor
valves, C&p systems, and cooling systems. the new equipment will be installed in the same building. new valves will
be self-standing and liquid cooled. the elimination of the aircooled system will free up significant space in the building.
the power transformers will be retained because they are in
good condition and still far from their life expectancy. the
filters will also be kept because they are redundant and can
be maintained on a piece-by-piece replacement basis.

MTDC Network
the Mtdc network interconnects Radisson and nicolet stations in Quebec and sandy pond in new england. each of
these installations includes 2 × 1,000 MW Cgs connected
with a 450-kVdc transmission line. these installations, built
by aBB (asea), were commissioned in 1992.
C&p systems attained their 20-year life expectancy and
started showing an increase in deficiencies. HQ and national
grid agreed to refurbish these systems in their respective
installations. the contract was awarded to aBB to upgrade
this complex system.
an extensive testing period took place at iReQ to minimize risks posed during the project phase and to ensure
proper operation of the new C&p systems. the system
behavior of the new and the existing control replicas was
compared and adjusted until satisfactory operation of the
control system was achieved. then there was a planned shutdown of nicolet station in the fall of 2015 for C&p installation and testing of both poles. During that period, Radisson
continued exporting to sandy pond. the upcoming second
stage will consist of replacing the C&p of sandy pond and
Radisson in the spring of 2016, which will reflect the refurbishment and operating experience gained from nicolet.

Némiscau/Albanel
némiscau and albanel are two similar sVC installations consisting of two sVCs per substation, built by ge in 1982. the
original design consisted of a 12-pulse, air-cooled thyristorcontrolled reactor (tCR) associated with fixed shunt capacitor banks. over the years, defective components in the analog
control were easily replaced. Valves have also been refurbished in collaboration with iReQ. the increased deficiencies
and the lack of spare parts were significant enough to necessitate a complete refurbishment project. since a new transformer
represents a major cost for the project, the transformers were
retained and reused in a modified 12-pulse configuration of
46

ieee power & energy magazine

±300 Mvar consisting of tCRs and thyristor switched capacitors (tsCs), which necessitate a new filter design. a significant
reduction of electrical losses is achieved in this configuration.
Valves were replaced with liquid-cooled thyristor valves and
new digital control systems were implemented. a new prefabricated building was installed to ease the installation.
site work requires extended outages since the new sVCs
are installed in the same physical area as the existing ones.
to limit the impact on the network, only one sVC per year
could be commissioned. the first sVC at nemiscau was
commissioned in november 2013 and the second a year later.
one of the first challenges was to secure the transition period
during which the new sVC was operating in parallel mode
with the existing sVC over the winter peak period. extensive
studies were conducted to characterize the older control and
adapt the new control for parallel operation. the replica of
the new control system was then connected to HQ's digital
simulator, as illustrated in figure 2, to evaluate the temporary control function prior to commissioning.

Remaining SVCs
the remaining sVCs outlined in table 2 need to be refurbished in the medium term. the exact schedule and detailed
refurbishment activities still need to be determined; however,
it has been established that only one sVC outage per year
will be scheduled.

New Brunswick Power-Eel River
Eel River HVdc Station Background
the eel River HVdc station is located in northeastern new
Brunswick about 20 km from the Québec-new Brunswick border, as shown in figure 1. the eel River HVdc
station is a BtB station capable of importing or exporting
up to 350 MW. the station has two 175 MW circuits that
allow it to maintain one circuit while leaving the other
circuit in operation.
the eel River HVdc station came online in 1972 as the
first HVdc station in the world built from solid-state HV,
high-current silicon thyristors with the use of fiber optics.
previous designs had utilized mercury-arc valves. in 1986,
the station's single-phase converter transformers were
upgraded from 55 MVa to 60 MVa per transformer. in
2011, the ieee recognized this first-of-a-kind technological
achievement and presented the eel River HVdc converter
station, and its owner new Brunswick power (nBp), with
the ieee 116th Milestone award, the 12th Milestone award
received in Canada.
the main driver for construction of the station in the early
1970s was the development of the Churchill falls hydro
project, which provided a significant block of inexpensive
surplus energy to eastern Canada. the 350-MW transfer
capability between Québec and new Brunswick through eel
River enabled nBp to transmit energy from Québec and labrador to new Brunswick and to other neighboring markets. in
march/april 2016

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