8. Gas Turbine Modelling for Power System Dynamic Simulation Studies

Gas turbines possess unique frequency response characteristics, as compared to other conventional (synchronous) generation technologies, which can significantly influence power system dynamics and stability during disturbances in the network. Many power systems are seeing increasing penetrations of combined cycle gas turbines (CCGTs), along with variable renewables, such as wind and solar generation, so an improved understanding of gas turbine characteristics during high- and low-frequency events and network faults is required in order to mitigate potential adverse system impacts. In particular, the impact of ambient conditions on unit rating, the temperature control system, gas turbine compressor intake, and associated components such as inlet guide vanes (IGVs) must be accurately modelled, particularly when operating at high output, in order to accurately assess the impact of CCGTs on stability issues. Therefore, this chapter aims to provide a comprehensive guide to developing a CCGT model using the DIgSILENT dynamic simulation language (DSL), including model initialisation. In addition, modelling of an open cycle gas turbine (OCGT) will be presented. Finally, a dynamic comparison of the CCGT and OCGT models will be examined using a demonstration test system.