Optimized Steam Turbine Governor Controlling Single or Multiple Grid Faults

Abstract

This paper uses simulation results to figure out how SIEMENS handles a single grid fault of a three–phase short circuit close to the power plant and a multiple grid fault of a load rejection due to a three–phase short circuit close to the power plant. The correct response of the steam turbine governor to the single and the multiple grid fault can increase power plant availability, prevent steam turbine trips and reduce overspeed. Therefore the power supply to the electrical grid can still be maintained, and in case of a de-stabilized electrical grid a black-out could be prevented. If the steam turbine trips caused by the single or the multiple grid fault the steam turbine runs down and has to be restarted. This could take several hours as worst case. During this time the power plant is not available to support and stabilize the electrical grid. If the steam turbine governor is able to handle the single grid fault, the power plant is still connected to the grid. This will not further stress the de-stabilized electrical grid. If the steam turbine governor is able to handle the multiple grid fault, the house load of the power plant will still be provided by the steam turbine. The operator could re-synchronize the power plant with the de-stabilized electrical grid as fast as possible. In both cases for the single and the multiple grid fault the power plant remains available by the optimized steam turbine governor.