From genuine challenge to world record

ABB brings extruded 525kV high-voltage direct current transmission systems to life

ABB’s record-breaking extruded cable 525 kilovolt (kV) high-voltage direct current (HVDC) transmission system lays the foundation for stronger, smarter and greener electricity networks.

Extruded HVDC cables systems have been used in voltage source converter (VSC) applications on land and under the sea. There are two types of HVDC – the classic technology using thyristors for voltage conversion, and VSC (voltage source converter) technology called HVDC LightTM, which uses transistors (IGBTs) for conversion. ABB introduced HVDC Light in 1999 at the 80 kV level as an adaptation of HVDC that transmits electricity in lower power ranges – under 100 to 1,200 megawatts (MW) – over short and medium distances. HVDC Light technology uses environmentally friendly oil-free underground, underwater or overhead lines.

In the ten years since its initial introduction, the voltage rating of HVDC Light systems increased six-fold to 320 kV in a relatively straight-forward line of development. However, a true paradigm shift was needed increase capacity beyond 320 kV for extruded cable applications, because insulating 525,000 volts (V) DC from ground with only a few centimeters of insulation is a genuine challenge.

It was a challenge worth tackling, however, because 525 kV systems can transmit so much more power – up to 2,600 MW in a cable pair, underground or subsea. This equals the power generated by several large nuclear power plants, or more than 500 large wind power plants. This HVDC system enables the transmission of more power over longer distances in a more compact way than traditional AC power transmissions. The cables can also be used underground where it is difficult or impossible to use overhead lines, e.g. for environmental concerns or in city in-feed applications.

A cable system comprises cables, joints and terminations. This system’s modified cross-linked polyethylene (XPLE) cable insulation material was developed in cooperation with Borealis, a leading manufacturer of polyethylene (PE) and polypropylene (PP) products. This material is extruded onto a copper or aluminum conductor. A 525 kV joint based on rubber technology was developed for prefabricated underground applications, i.e. when cables are delivered on drums for land applications. Also, an in-house factory joint for sea applications was developed for jointing batches of cables into a long length loaded onto a ship. The 525 kV terminations are inspired by ABB’s high-voltage bushing technology. You can find more details in our white paper.

The new world record-setting cable voltage is yet another example of the strength of ABB’s business unit Grid Systems, which is the sole supplier of converters, power semiconductors and cable systems for HVDC applications. I am very proud of this pioneering accomplishment by a cross-functional team made up of dozens of experts and skilled technologists. This achievement is the result of more than six years focused, hard work from initial testing of various promising material compositions to final type tests in our high-voltage laboratories. A key enabler for success has been decades of devotion to materials technology driven by our corporate research laboratories. As with all great innovations, even sliced bread, harvesting cannot be done unless the seeds are properly planted.

I believe the introduction of our new extruded 525 kV cable system is a tremendous way for ABB to celebrate the 60th anniversary of HVDC cable transmission. It demonstrates that despite 60 years of experience and more than 170 commercial installations, ABB continues to push the envelope of HVDC technology, which continues to develop rapidly. I have no doubt ABB’s newest high-power cable transmission system will play a major role in building the grid of the future. Come visit us at our stand during the Cigré technology fair next week to see an exhibit of the new 525 kV cable system!

ABB’s Grid Systems business unit supplies utilities and industrial companies with onshore High-Voltage Direct Current (HVDC) solutions, turnkey AC and DC connections for offshore wind farms, high-voltage DC and AC power cable systems, power semiconductors and power system studies.

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About the author

Magnus Callavik

Vice president and General Manager ABB Sifang Power Co. Ltd., Previously Technology Manager for BU Grid Integration, a part of ABB’s Power Grids division
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