Testing and model validation for combined-cycle power plants

One of the most significant changes in the generation of electric power over the last few years is the widespread application of combined-cycle technology for new power plants. As the new generation coming on-line is predominantly gas turbines and combined-cycle the importance of accurate models of these types of plants is growing rapidly. Larger blocks of these units will have a major effect on the response of the power system voltage and frequency to major disturbances. Accurate simulation models are required to analyze the system response to such disturbances. The accuracy of simulation models is dependent on two key factors: having appropriate model structures and having the proper parameters to fit into that model structure. Testing of generating units to determine generator, excitation system, and governor parameters has been occurring for some time. The extension of the techniques developed in these efforts to the testing of combined-cycle plants is discussed in this paper. This paper focuses on the testing approach required and gives examples of the results acquired in several tests. It shows how simulation models can be developed that closely match the recorded responses