Power converter eliminates wind turbine downtime

The Switch, a provider of megawatt-class permanent magnet generator and full-power converter packages for wind power and other new energy applications, announces it has launched its next-generation full-power converter (FPC) series. The new converter eliminates wind turbine downtime, ensuring that turbines continually produce energy for the grid.

The new FPC is the result of a comprehensive R&D effort undertaken to meet the evolving needs of major players in the global wind power industry. Of the numerous improvements The Switch made in its FPC series, most focus on increasing wind turbine reliability. Optimum converter performance ensures turbine availability, a key metric of wind energy production. Recent tests prove the FPC is fully compliant with the strictest grid code requirements and fault ride-through standards, including those set by the International Electrotechnical Commission (IEC). 

While turbines with permanent magnet generators (PMGs) haven’t yet been deployed in large numbers, the technology is rapidly gaining adoption among high-profile turbine manufacturers. According to a recent report released by Denmark-based MAKE Consulting, PMGs have emerged as a preferred technology for new multi-megawatt and offshore turbines due to such factors as increasing turbine size, and the need for improved grid compatibility and efficiencies. 

To reach the highest reliability standards, The Switch’s software solutions enable tight communication and coordination between the FPC and wind turbine control systems, which gather data for turbine management. The converter tracks commands from the turbine controller and transfers everything it measures to the turbine control system for processing. If the turbine experiences a lack of coolant flow, for example, the converter interacts with the controller to adjust production accordingly, ensuring against shutdown so the turbine produces the maximum amount of energy possible.

Other key features include:

  • Improved thermal management: Converting energy from one form to another results in energy loss, and generates heat that can harm turbine components. For the new FPC, The Switch improved thermal management and cooling functionality, increasing operational reliability and ensuring longer life for all components. 

  • Enhanced generator-side functionality: On the generator side, The Switch has developed a number of enhancements, including a new liquid-cooled DU/DT filter to smooth generator waveforms; a generator inverter that converts electricity from ac to dc, as well as controlling generator torque; and a controlled compact generator breaker that isolates the PMG from the converter when the turbine is at a standstill.

  • DC link: In the dc link, which connects the generator inverter and the grid inverter, the FPC includes a dc pre-charging circuit that prevents excessive in-rush currents during start-up. The dc link capacitors are integrated in the inverters, making the module compact and easily cooled. A dynamic electric brake, comprising the dc chopper and resistor bank, prevents the dc link from overvoltage during sudden grid loss, enabling smooth torque control through the event. With the optional heavy-duty resistor bank, the converter keeps torque and speed constant during a grid fault, protecting the generator and other mechanical structures within the wind turbine from stress during grid fault ride-through. 

  • Improved grid-side performance: Grid-side performance has been significantly improved, with fault ride-through and lower grid harmonic content. Improved synchronization means in-rush current is lower when the converter connects to the grid. Further, the grid inverter converts electricity from dc to ac and controls the dc link by feeding generator power to the grid. The new grid LC filter, with its choke and capacitor bank, smooths grid waveforms. 

  • Smarter protective components: With smart protection management, the failure of one component does not impact other components. Protective components include the main circuit breaker, which provides isolation from the grid and integrated digital protection relay, and fast semiconductor fuses that protect the converter in case of failure.
Improved onboard diagnostics: Controllers can now readily collect data from the converter and analyze it. Converter power modules integrate dedicated fault-event buffers, which store a pre-set number of alarms and faults with the most important status and monitoring values.

For more information, contact The Switch, 11 Executive Dr., Hudson, NH 03051. Phone: (603) 886-9010.

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