Feed-in converter SD2R as Basis for the Utilization of Renewable Energy

The feed-in converter SD2R system can be integrated in many innovative solutions and acts as interface between a high-speed generator and the public low-voltage grid. The device is now available with output powers of 15 kW and 100 kW.

Independent of the functional principle of the innovative system, usually a high-speed generator converts rotational energy into electric energy. The generator operates in a speed range between approximately 15,000 to 120,000 revolutions per minute. But frequencies of up to 2000 Hz result in considerable demands on the downstream power electronics. Feed-in converters of the series SD2R by SIEB & MEYER feed the generated current into the public grid. The series comes with different dimensions and powers between 15 and 100 kW. "The feed-in converters are used in ORC systems, for example, that generate electricity from waste heat. Other fields of application are expansion or micro gas turbines as well as high-speed flywheel energy storage units", says Ralph Sawallisch, key account manager for feed-in technology at SIEB & MEYER.

The feed-in system SD2R is a complete solution including the frequency converter with the corresponding mains inverter. It complies with the applicable standard VDE AR-N 4105. The electronics especially developed for high-speed motors and generators are the basis of the system that allows generator operation as well as motor operation with excellent control performance. Thereby SD2R accounts for all technical requirements of the generator and processes. The integrated ballast circuit affects the DC intermediate circuit and prevents excess voltage. This protects the turbine against overspeed even when a mains failure occurs. An external ballast resistor picks up the power. Interesting side effect: Since the intermediate circuit supplies the system with energy, the voltage supply of the control is not interrupted in case of a mains failure as long as the generator rotates. Therefore, monitoring the operating state during braking is possible.

SD2R can be dimensioned and designed flexibly according to the specific environment and requirements of an application. This makes the system particularly attractive for all special applications. One possible design is a 15 kW control panel with LCD display and air cooling to be integrated in the system. Another option is a stand-alone switch cabinet with liquid cooling and an output power of 40 kW or 100 kW. During system design additional functions for emergency supply of important components, e.g. magnetic bearings, as well as safety functions, e.g. grid monitoring or ballast circuit, can be implemented. A sensorless speed control of SD2R reduces costs and increases the availability of the system.

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