Optimization of Combined Cycle Power Plant Using Sequential Quadratic Programming

Abstract

The thermal-economic optimization of a combined cycle power plant (CCPP) which can provide 140 MW of electrical power is discussed in this paper. The CCPP is composed of a gas turbine cycle (including, air compressor, combustion chamber, gas turbine), heat recovery steam generator (HRSG), steam turbine, condenser system, and a pump. The design parameters of such a plant are compressor pressure ratio (rAC), compressor isentropic efficiency (ηAC) gas turbine isentropic efficiency (ηGT), and turbine inlet temperature (T3), pinch difference temperature (ΔTpinch), steam turbine inlet temperature (Ta), steam turbine isentropic efficiency (ηST), and pump isentropic efficiency (ηPUMP). The objective function was the total cost of the plant in terms of dollar per second, including sum of the operating cost related to the fuel consumption, and the capital investment for equipment purchase and maintenance costs. The optimal values of decision variables were obtained by minimizing the objective function using sequential quadratic programming (SQP). The effects of change in the demanded power and fuel price on the design parameters werestudied for, 100, 120, and 140MW of net power output.