Solar hybrid gas turbine technology has the potential to increase the efficiency of future solar thermal power plants by utilizing solar heat at a much higher temperature level than state of the art plants based on steam turbine cycles. In a previous paper the authors pointed out, that further development steps are required for example in the field of component development and in the investigation of the system dynamics to realize a mature technology for commercial application [1].

In this paper new findings on system dynamics are presented based on the simulation model of a solar hybrid gas turbine with parallel arrangement of the combustion chamber and solar receivers. The operational behavior of the system is described by means of two different scenarios. The System operation in a stand-alone electrical supply network is investigated in the first scenario. Here it is shown that fast load changes in the network lead to a higher shaft speed deviation of the electric generator compared to pure fossil fired systems. In the second scenario a generator load rejection, as a worst case, is analyzed. The results make clear that additional relief concepts like blow-off valves are necessary as the standard gas turbine protection does not meet the specific requirements of the solar hybrid operation. In general the results show, that the solar hybrid operational modes are much more challenging for the gas turbines control and safety system compared to pure fossil fired plants due to the increased volumetric storage capacity of the system.

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