Ultra High Voltage DC Systems
Ultra High Voltage DC Systems
Ultra High Voltage DC Systems
3500
3000
2500
MUSD
Losses
2000
Line cost
1500
1000 Station cost
500
0
765 kV AC 500 kV DC 800 kV DC
2 ABB
800 kV UHVDC
Number
of lines:
ABB 3
800 kV HVDC
Transformer bushing testing Dielectric testing of 800 kV UHVDC valve hall bushing
4 ABB
800 kV UHVDC
* STRI is an independent
technology consulting
company and accredited
high-voltage laboratory
located in Ludvika,
Sweden.
www.stri.se
The key issues handled in the project the transformer subject to high DC voltages.
1. With up to 9 000 MW being carried on one The photos on pages 4 and 7 show the
pair of overhead lines, extreme reliability is transformer and wall bushing during test.
obviously essential. Therefore a completely 4. Design criteria for air clearance have been esta-
new station design has been developed to blished. Extensive tests were done at extre-
achieve these requirements. The converters mely high, previously unused voltages. The
must not fail more than once every twenty-five photo to the right show a discharge at over
years. Increased availability is achieved by ex- 2 million volts. These flashes are more than Valve hall clearance testing. Testing
of multiple air gap in corner. Several
tensive sectioning of both the main circuit and ten meters long. The photo is taken during flashovers superimposed in one photo.
the auxiliary systems. In addition, all control an insulation gap test in one of the high-vol-
and protection systems are duplicated, as well tage laboratories in Ludvika.
as auxiliary systems such as auxiliary power 5. The DCC 800 control and protection system
and emergency battery systems. is a futher development of the proven Mach2
2. New types of all the high-voltage devices subject system. Focus has been to satisfy the extreme
to DC have been developed and fitted with reliability demands.
newly-developed polymer insulating materials. 6. A new thyristor and thyristor valve have been
Examples of such devices are voltage dividers, developed to handle the increased voltage
bypass switches, radio interference capacitors, and current.
disconnectors and post insulators.
7. Finally, all critical devices are undergoing
3. One of the main goals of the project was to de- endurance testing in a special endurance
velop a transformer and a bushing for 800 kV. testing station built by ABB at STRI* in Lud-
The foundation for this was the basic research vika. The elevated voltage test extends over a
mentioned above. Prototype bushings were year. The purpose of the test is to verify the
produced and type-tested. For the transformer, long-term characteristics of the components
a mock-up was built to simulate the parts of used.
ABB 5
800 kV UHVDC
The market today and tomorrow and southern parts of the country, so the genera-
In China and India, the demand for energy is ted electricity must be transmitted 1 500 to 2 000
growing dramatically. Every year, China installs kilometers (up to 1 200 miles). Up until now, 600 kV
new power generating capacity equivalent to DC has been used for long-distance transmission
the entire installed capacity of Sweden. Major of electric power, over distances of around 1 000
expansion of available hydro power will be kilometers (about 600 miles).
needed to satisfy this demand. With the introduction of 800 kV DC it will be possible
For China, this means to further exploit large to transmit power as far as 3 000 kilometers (over
hydro resources in the West of the country. 1 850 miles) with reasonable transmission losses.
However, the power is needed in the eastern China is currently planning to build one 800 kV
6 ABB
800 kV UHVDC
DC line per year over the next ten years, with a Apart from China and India, investigations are
capacity of between 5 000 and 6 400 MW per line. going on to use 800 kV lines in southern parts
India plans to expand hydro power in the north- of Africa and Brazil.
eastern part of the country. As in China, the de- The conclusion is that 800 kV DC will account
mand for power is far away from the resources, for a significant part of world growth in power
so also here the power will have to be transmitted transmission capacity over at least the next ten
as far as 2 000 km (up to 1 200 miles). India is years.
currently planning to build one 800 kV DC line
every two years over the next ten years, with a
capacity of 6 000 MW per line.
ABB 7
ABB Power Technologies AB
Grid Systems - HVDC
SE-771 80 Ludvika, Sweden
Tel: +46 240 78 20 00
Fax: +46 240 61 11 59
www.abb.com/hvdc Pamphlet no POW-0043