Economic Analysis On Peak-regulation Of GTCC Cogeneration Unit With Extraction Heating

Gas turbine combined cycle（GTCC）power and cogeneration units are facing deep peak-load regulation with the development in high-proportion renewable energy.This paper studies the peak-regulating range and peak-regulating economy,which provides some guidance to the peak-load regulation operation of cogeneration unit.The simulation model for overall part-load characteristics of cogeneration system based on heavy-duty gas turbine was built,including stage-stacking method for compressor and modular analysis for performances of heat recovery steam boiler.By comparing and analyzing the operation line of gas turbine under different regulation modes,it is necessary to make clear the exhaust temperature of gas turbine or the law of sliding pressure of steam turbine for the performance simulation of cogeneration unit.In order to investigate the economy of domestic cogeneration projects,the cost model based on Levelized Cost of Energy was built to calculate the generating cost of GTCC power projects on different class and capacity;and the sensitivity analysis of the generating cost of GTCC power project on different factors was made.The simulation process was applied in the case of a 390MW-class cogeneration unit,and by introducing output to fuel cost ratio,the thermal economy analysis of combined cycle cogeneration unit was made,where the load regulation depth and output to fuel cost ratio were investigated at overall part-load conditions.The variation of the peak-regulating capacity and the comprehensive energy utilization rate of the system with the heat supply and IGV degree was studied.It concludes that,the load regulation depth of the system comes to 31.24%at designed heat-power ratio r₀=0.4.When price ratio of power/fuel is 2.806 and that of heat/fuel is 1.215,at designed heat-power ratio r₀=0.2,output to fuel cost ratio nearly stabilizes at 1.611,which indicates weak influence of power peak regulation on the economy;at r₀>0.2,the system gains a positive economic advantage from power peak regulation.However,in the case of output to fuel cost ratio expected as 1.41,the cogeneration unit bears a loss when the power load rate is less than about 60%at pure condensation.This work provides theoretical and practical reference for decision-making of GTCC power project.