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Within power plants, several physical, chemical and mechanical processes are conducted to transfer the energy, stored in fossil fuel, into electrical energy. This energy conversion is divided into several stages. Hitherto, the largest conventional power plants employ steam turbines as prime movers to drive a generator. Hence, a steam turbine is one module to convert heat energy into mechanical energy. And thus it is one link in the chain of energy conversions with the aim of generating electrical energy. Today, steam turbine industry faces numerous challenges concerning efficiency, commissioning time, start-up times, operation, availability, safety, cost-effectiveness, etc. Many of these tasks can be supported by simulating the transient operational behaviour of the turbine in advance. For example, the commissioning time can be shortened if the turbine controllers are initialized with well-tuned pre-set parameters; cost-effectiveness can be increased by setting aside unnecessary devices and exactly determining material specifications; safety may be increased by predicting the impacts of failures and thus taking the necessary precautions. Different tasks require different details regarding the employed turbine simulation model. Thus, the turbine controller may be well tuned with less complex simulation models of turbine, generator and electrical grid, whereas detailed studies of failures, mainly the transient behaviour which may lead to serious damages, may require detailed modelling of the turbine-internal thermodynamic processes. Here, a brief overview of models which simulate the transient thermodynamic behaviour of a steam turbine is presented. Three different approaches will be introduced and compared with respect to different operating situations. Also, special attention is directed towards the time dependence of critical states, mainly turbine speed and pressure development in certain areas. The first model is based on a simple, linear approach and is suitable of giving a quick overview. The second one incorporates more details and is useful if the operating point is close to the design point. Finally, the last model incorporates mass and energy balances as well as the major non-linearities. Hence it depicts the turbine behaviour over a large range of operating points.

For the experimental verification of a new emergency stop and control valve design extended tests on a low pressure as well as a high pressure air test rig were performed. As the required thermodynamic parameters for a full scale test cannot be met, a scaled version of the valve design was tested. The scaling was done taking into account the laws of similitude. The inherent valve characteristics as well as pressure distributions and forces were gathered by means of steady and unsteady probes. While the tests in the low pressure test rig were performed at similar Mach numbers, the high pressure tests were performed also with Reynolds numbers sufficiently similar. A transformation of the pressure pulsations to the real steam valve was done by means of the Strouhal number. In the low pressure test rig ambient conditions were used for the inlet air. A vacuum pump was delivering the airflow through the tested valve model. The valve model was equipped with approximately 50 test points. For the high pressure test rig a six-stage radial compressor with interstage cooling was used. The valve model was equipped with approximately 40 test points. Due to the limitations of the compressor and other adjacent systems the tests in the high pressure test rig were conducted with a stepped operational concept using different mass flows and inlet pressures for the tested valve model. The inherent flow characteristics as well as the pressure pulsations of both measuring campaigns were compared with one another. Matches as well as mismatches are discussed. Additionally, the results were compared with steady state and transient CFD simulations, which is described in Part 2 (GT2014-25117).

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