With the increasing prevalence of renewables, it is important to optimize combined cycle power plants during transient conditions to better compliment the variable generation of renewable energy generators. There is a demand for dynamic heat recovery steam generators (HRSG) models that may enable improved control designs. Sufficiently accurate real-time simulations of HRSGs may serve as soft sensors and state estimators during transient conditions. Furthermore, real-time simulations of HRSGs can be used for operator training which does not incur the inherit risk of using plant hardware. The focus of this research is on the development towards an integrated dynamic closed loop HRSG model, including a three-pressure level HRSG and a steam turbine, capable of real-time simulation. To that end, a simple dynamic steam turbine model was developed and integrated with the HRSG to accurately model the dynamic interaction of both systems. A dynamic control volume was used to model the mixing of IP steam turbine steam exhaust and LP superheater steam. Attemperators were modeled at superheater exits in the HP bypass flow path. Steam turbine and bypass flow paths were modeled, including their respective valves, enabling the simulation of transient conditions. During testing, simultaneous operation of both valves was used to simulate an HRSG and steam turbine running with hot start conditions. Simulation results for the integrated HRSG and steam turbine show good agreement with data provided by Siemens Energy. Once the closed loop simulations were demonstrated, a full HRSG model was created. This model was compiled and downloaded to Siemens PLC hardware and run without active controls at steady state conditions. The simulation results demonstrated numerical stability when run at real-time.


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Graduation Date





Das, Tuhin


Master of Science in Mechanical Engineering (M.S.M.E.)


College of Engineering and Computer Science


Mechanical and Aerospace Engineering

Degree Program

Mechanical Engineering; Mechanical Systems


CFE0009154; DP0026750





Release Date

August 2022

Length of Campus-only Access


Access Status

Masters Thesis (Open Access)