When a major wind turbine manufacturer placed an order for ABB’s PCS6000 converters for a project in the United States, ABB began the complex process of obtaining UL certification for the product. Certification by UL is mandatory for wind turbine converters delivered to the US market. One factor that complicated the issue was the lack of an applicable UL Standard for MV wind turbine converters.
“This was a first-of-its-kind project and new technology for the market, and there was no applicable UL Standard we could utilize,” says Mirko Bautz, Vice President of Global Accounts at UL. “We started by working with ABB to determine which UL Standard would be most relevant. We decided the best approach would be to apply an existing safety Standard, UL 6141. We worked closely with ABB throughout the certification process and brought it to a successful conclusion.”
Personnel from UL’s offices in Europe and from UL’s headquarters in Northbrook, Illinois, worked with ABB staff from the wind turbine converter engineering unit in Switzerland and the factory in Poland. The process included extensive component and design reviews, as well as type testing.
Low and medium voltage converters for all main markets
“UL certification for the PCS6000 converter, following collaboration to develop the new Standard, is great news for turbine OEMs and operators in North America,” says Chris Poynter, Managing Director of ABB System Drives. “They can take advantage of the simplicity and performance of medium voltage converter technology, and there is now a clear benchmark for safety, performance and grid connectivity for everyone.”
“We are the only manufacturer able to provide both medium and low voltage converters for wind turbines, and UL certification enables us to supply our entire range to customers in all the world’s main markets.”
ABB is the leading supplier of MV converters, and up to now the main focus has been on the European and Chinese markets. With UL certification there is great potential for sales of MV converters in North America.
Helene Ebach, Daniel Schmelzle, Frank Kinces, Jonas Wahlström, Alessandro Severino 
ABB's wind converter 
ABB's PCS6000 wind turbine converter
Helping wind park operators to maintain profitability
Wind turbine power levels are currently increasing, especially offshore, because higher powers enable wind park operators to maintain profitability at a time when subsidies are declining. Medium voltage operation is a good fit with this trend because it provides a number of benefits at higher power levels.
The higher voltage level of MV converters means lower currents in the electrical drivetrain. As a result, smaller and less expensive cabling can be used. The converter has a more compact footprint and is lighter in weight. The PCS6000 converter also features high efficiency IGCT (integrated gate-commutated thyristor) technology, as well as an advanced control algorithm that optimizes the operation of the generator while minimizing losses in the generator windings. The converter’s low part count and fuseless design ensure high availability. These advantages help wind park operators to achieve a good return on their investment while getting the lowest LCOE (levelized cost of energy). The PCS6000 MV converter is already operating in the world’s highest power turbines.
In addition to UL certification, the PCS6000 has product certification from the China General Certification Center, CGC, and from DNV-GL. It meets grid code requirements in the United States, major European and several other countries.
More than 200 PCS6000 MV converters are operating in offshore wind parks in the North Sea, Baltic Sea and off the coasts of China. ABB’s deliveries of low voltage wind turbine converters total more than 15,000 units.
