IEEE Power & Energy Magazine - March/April 2016 - 79

A number of factors needed to be considered
when designing a solution to perform
the refurbishments.

The Nebo SVC refurbishment included one thyristor
switch capacitor (TSC) and one thyristor controlled reactor
(TCR). Both required replacement of the thyristor valves and
accessories, thyristor cooling system, and the complete control and protection system. Powerlink Queensland requested
the refurbishment be performed in two stages. The first stage
was to replace the TSC valve since it was damaged and out
of service. The second stage was for the complete control
and protection system of the Nebo SVC.
One of the big challenges for the Nebo SVC refurbishment was the integration of a Siemens TSC valve into a nonSiemens control and protection system. It was important to

figure 5. A mobile SVC with cables installed at site.
(Image used with permission from Siemens Industry, Inc.)

figure 6. The cable bundles on site. (Image used with
permission from Siemens Industry, Inc.)
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ieee power & energy magazine

quickly recover the Nebo SVC from its damaged state. The
control and protection system was completely replaced at
a later time. This required Siemens to initially perform an
extensive investigation to properly interface with the existing control. The new thyristor valves and cooling system
were delivered and installed within five months. The complete control and protection system and the TCR valve were
successfully refurbished at a later date.
The nine other SVCs for the railway system are located
approximately 1,000 km northwest of Brisbane. The location of each SVC is shown in Figure 4. The Nebo SVC is
excluded as it had its own standard refurbishment discussed
already. The remaining nine refurbishments involved replacing the thyristor valves, the cooling systems, and the webbased control and protection systems. The refurbishments
were necessary due to this equipment being almost 20 years
old with a high risk of failure.
A number of factors needed to be considered when
designing a solution to perform the refurbishments. Extended
outages or the removal of any of the SVCs would have an
unfavorable impact on the electrical network of the railway.
Therefore a critical design criterion was keeping outage time
to a minimum. The hardware needed to meet the electrical
requirements, be readily transportable, and able to be rapidly
installed and removed. Changes at each individual site had
to be flexible and adjustable and consist of only minor wiring
changes and software alterations. The power connections to
the busbar needed to be flexible and easily removable to
minimize downtime. The components would be designed
for possible short circuits, and a standard interface was used
for the control cables. The dimensions had to be such that
it would fit into available space at each substation due to
size constraints. Finally, the design had to account for harsh
environmental conditions, such as very hot temperatures and
dangerous wildlife, and be safe for the equipment as well as
the personnel performing the work.
The solution involved constructing a mobile SVC using
a 40-ft skeleton trailer to house all of the necessary components that kept within the size constraints. This allowed
the solution to be applicable to all of the sites that required
refurbishment. The component ratings were designed to
accommodate the largest SVC (Coppabella). This made
the components capable of handling the requirements of
the smaller SVC installations too. Ratings of the different
sites are shown in Table 1. The execution involved only
one mobile SVC that relocated from site to site after each
march/april 2016

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - March/April 2016