Dynamic simulation and control of a combustion turbine process for biogas derived methane

Abstract

Combined cycle power plants that use both gas and steam turbines have much higher efficiencies than traditional steam power plants and are increasingly utilized for both natural gas and biogas based power generation. Gas is burned using high-pressure air to produce a high-temperature, high-pressure gas that is fed into a gas turbine driving a generator. The lower-pressure exhaust gas from the combustion turbine is still at high temperature, so it can be used to produce steam to drive a steam turbine that generates additional power.This paper illustrates that the dynamic simulation of these turbine systems is not straightforward because of numerical integration and variable specification (free or fixed) issues. An effective control structure for handling the very large hour-to-hour daily disturbances in electric power load is developed. The numerical example is for a low-pressure biogas process, but the turbine simulation procedure is applicable to any combustion turbine process.