Особенности представления газотурбинных и парогазовых установок в расчетах переходных процессов в электроэнергетической системе

Abstract

Gas turbine units and combined-cycle plants account for a significant share in the mix of generating capacities. New conditions of the energy market have an effect on the electric power system features. In some countries, gas turbines have become the main reserve for frequency control in the grid. Under such conditions, accurate modeling of gas turbines with due regard to their specific features is becoming of significant importance. A detailed gas turbine model cannot be constructed without carefully analyzing the behavior of the gas turbine unit control systems during transients. The article describes the specific features of gas turbine units and combined-cycle plants that have to be taken into account in studying electromechanical transients and frequency control matters in the grid. These features include, in particular, a drop of the gas turbine maximum power output during frequency excursions with respect to its nominal level, unstable operation of control systems, and blowout under the conditions of large disturbances caused by short-circuit faults or abrupt changes of load. The gas turbine models used in the modern software systems are subjected to a comparative analysis, and recommendations on selecting the gas turbine model are given depending on the study objectives and power plant operating modes. Calculations of electromechanical transients in an electric power system carried out using different gas turbine models are presented. Differences between the behavior of gas turbine unit and combined-cycle plant control systems during transients are shown. Some problems concerned with the influence of gas turbine units on the performance of a power system containing a large fraction of renewable sources of energy are discussed.