Study On Natural Gas Combined Cooling Heating And Power Energy System Operation Optimization

It is a time of increasing concerns over combined cooling,heating and power(CCHP),and CCHP does not need long-distance transmission of large power grids and construction of extra high voltage transmission lines.So the development of CCHP can reduce the line loss and the investment cost of the power transmission and distribution construction is decreased significantly.In addition,with the development of the society and more and more serious influences of fog and haze weather,awareness of environmental protection is increasing gradually.Natural gas more and more receives the favor by the clean energy.Study on natural gas CCHP system operation optimization is a hotspot currently working to achieve matching and coordination between energy supply and customer load.Detailed analysis on CCHP system before and after retrofit is made in this paper.Mathematical models are built on gas turbine,boiler,steam turbine,auxiliary boiler,absorption chiller and electric refrigerator.It makes the results of operation optimization on gas-steam combined cycle system more accurate.This paper takes lowest running costs as single objective function,and highest energy economic ratio together with CO2 reduction rate as multiple objective function.This optimization model is formulated as typically mixed-integer nonlinear programming(MINLP)problem.LINGO and MATLAB is used to solve this model and analyze the optimization results.Through comparative analysis,it shows that electricity price plays a dominant role when taking lowest running costs as single objective function,and peak-to-valley period of time plays an important role to the optimization results.When taking highest energy economic ratio together with CO2 reduction rate as multiple objective function,meeting the user demands with gas plant is a priority,and using electricity from grid under the condition of capacity is not enough.Moreover,CCHP has a very obvious positive effect on energy conservation and environment protection.Comprehensive evaluation index system is built in this paper and economy index,energy conservation index,environmental protection index,technical advancement,reliability and security are all analyzed in detail and taken into account in assessment of natural gas CCHP system.It brings more comprehensive evaluation result and improves the deficiencies that other researchers only pay attention to economy.Original 1-9 method for weight scale of the evaluation index,analytic hierarchy process,expert scoring method,half-trapezoid fuzzy membership degree function are contributed to the building-up of the CCHP system assessment model.It combines subjective views with objective data to make the evaluation result more scientific and reasonable,and improves the deficiencies that traditional methods are too subjective.It makes a case study using this model according to the practical application in the last part of the article.