IEEE Power & Energy Magazine - March/April 2016 - 72

These powerful driving forces demonstrate how midlife
or proactive improvements in their systems can save operators
valuable time and money.

It is located at the ZESA Insukamini 330 kV substation
in Zimbabwe, close to the coupling point for the 400-kV
interconnection to South Africa. This 405-km-long link
forms part of an ac connection running in parallel with
the Cahora Bassa HVdc link. In 2014, an upgrade of the
SVC was performed. The purpose of the compensator is to
provide high-speed dynamic voltage control under certain
system loading and outage conditions. The single 400-kV
interconnection between Matimba and Insukamini is relatively weak, and unless proper measures are taken, poorly
damped, low-frequency (<0.5 Hz) active power oscillations
tend to appear between South Africa and Zimbabwe. The
SVC is equipped with a power oscillation damper to mitigate these power oscillations. With the SVC in operation,
stability and power transfer margins have been increased
by approximately 150 MW in the existing power corridor.
The SVC consists of a thyristor-controlled reactor rated
150 Mvar, a thyristor-switched capacitor rated 150 Mvar,
and harmonic filters rated together at 50 Mvar. By control
of these branches, the -100/+200 Mvar operating range of
the SVC is achieved.
In 2014, after many years of successful operation, it was
decided to upgrade the Insukamini SVC in Zimbabwe by
replacing vintage key components with the latest technology,
thereby extending the life span of the SVC. The two thyristor valves including cooling plant were exchanged, and new
protective equipment was installed. The control system was
upgraded to ABB's latest generation of MACH, a microprocessor-based system that is built around an industrial PC with
add-in circuit boards and I/O racks connected via standardtype field buses. Facilities for remote operation and supervision are integrated into the system.

Provide Lifetime Support
The availability and reliability of HVdc and FACTS links is
of prime importance. Owners must address needs for training; spare parts and consumables; maintenance; repairs;
engineering and consulting; life extensions, upgrades, and
retrofits; end of life services; and replacements. Outside contractors or manufacturers can provide these services.
An example of a long-term commitment is the Estlink
HVdc light project, where the following services have been
provided since the link was commissioned in 2006:
✔ HVdc converter station regular weekly inspections
✔ regular preventive and corrective maintenance
✔ yearly planned maintenance
march/april 2016

✔ 24/7 telephone support for troubleshooting assistance,

complemented by remote access capability of the control and protection systems by technical experts
✔ additional services, such as spare part supplies.
Recent FACTS service contracts include industry/mining and
utility customers, where the following services have been provided:
✔ emergency response 24/7 including on-site and remote
service
✔ scheduled maintenance, onsite and remote
✔ spare parts and updates
✔ training
✔ long-term service agreement with Evergreen.
Old HVdc and FACTS systems are still very reliable due to
their original rigid design, equipment, installation, and service. This
original advantage, combined with careful and methodical maintenance of the equipment and system, as well as midlife equipment
and system upgrades, will enable these installations to provide
many additional years of successful operation. Upgrades increase
the performance of existing systems, extend their lifetimes, reduce
maintenance requirements, increase availability and reliability, and
significantly improve system technology. These powerful driving
forces demonstrate how midlife or proactive improvements in their
systems can save operators valuable time and money.

For Further Reading
H. Bjorklund, "Upgrading the control system of the Square
Butte HVDC transmission," in Proc. CIGRE Osaka Symp.,
Nov. 2007, Paper 214, pp. 1-7.
P. Goosen, C. Reddy, B. Jonsson, T. Holmgren, O. Saksvik, and H. Bjorklund, "Upgrade of the Apollo HVDC converter station," in Proc. CIGRÉ 6th Southern Africa Regional
Conf., Aug. 2009, Paper 107, pp. 1-6.
M. J. Beshir and H. Bjorklund, "Upgrading the intermountain HVDC project to handle 480 MW additional wind
power," in Proc. CIGRÉ, Paris, 2012, Paper B4-108, pp. 1-8.
H. Björklund and A.Thelenius, "First-class service," pp.
40-43, July 2014.

Biographies
Hans Björklund is with ABB, Sweden.
Anna Thelénius is with ABB, Sweden.
Urban Elgqvist is with ABB, Sweden.
Jens Peter Kjærgaard is with Energinet.dk, Denmark.
Colin Reddy is with Eskom Holdings Limited, South Africa.
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