Ultra-supercritical(USC) unit is more and more popular in coal-fired power industry.In this paper,closed-loop identification based on subspace model identification(SMI) is introduced for superheated steam temperature ...Ultra-supercritical(USC) unit is more and more popular in coal-fired power industry.In this paper,closed-loop identification based on subspace model identification(SMI) is introduced for superheated steam temperature system of USC unit.Closed-loop SMI is applied to building step response model of the unit directly.The parameters selection method is proposed to deal with the parameter sensitivity and improve the reliability of the model.Finally,the model is used in model identification of real USC unit.展开更多
Improving the primary steam parameters is one of the most direct ways to improve the cycle efficiency of a powergeneration system. In the present study, the typical problem connected to the excessively high superheat ...Improving the primary steam parameters is one of the most direct ways to improve the cycle efficiency of a powergeneration system. In the present study, the typical problem connected to the excessively high superheat degree ofextraction steam in an ultra-supercritical (USC) double-reheat unit is considered. Using a 1000 MW power plantas an example, two systems (case 1 and case 2) are proposed, both working in combination with a regenerativesteam turbine. The thermal performances of these two systems are compared with that of the original systemthrough a heat balance method and an exergy balance strategy. The results reveal that the two coupled systemscan significantly reduce the superheat degree of extraction steam, turbine heat rate, and coal consumption of theunit and improve the energy utilization efficiency. These results will provide useful theoretical guidance to futureinvestigators wishing to address the general problem relating to energy conservation and modelling of the coupledextraction steam regenerative system of USC double-reheat units.展开更多
Ultra-supercritical(USC) coal-fired unit is more and more popular in these years for its advantages.But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling...Ultra-supercritical(USC) coal-fired unit is more and more popular in these years for its advantages.But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling among inputs and outputs. In this paper, model predictive control(MPC) method based on multi-model and double layered optimization is introduced for coordinated control of USC unit running in sliding pressure mode and fixed pressure mode. Three inputs(i.e. valve opening, coal flow and feedwater flow) are employed to control three outputs(i.e. output power, main steam temperature and main steam pressure). The step responses for the dynamic matrix control(DMC) are constructed using the three inputs by the three outputs under both pressure control mode. Piecewise models are built at selected operation points. In simulation, the output power follows load demand quickly and main steam temperature can be controlled around the setpoint closely in load tracking control. The simulation results show the effectiveness of the proposed methods.展开更多
700°C double reheat advanced ultra-supercritical power generation technology is one of the most important development directions for the efficient and clean utilization of coal.To solve the great exergy loss prob...700°C double reheat advanced ultra-supercritical power generation technology is one of the most important development directions for the efficient and clean utilization of coal.To solve the great exergy loss problem caused by the high superheat degrees of regenerative steam extractions in 700°C double reheat advanced ultra-supercritical power generation system,two optimization systems are proposed in this paper.System 1 is integrated with the back pressure extraction steam turbine,and system 2 is simultaneously integrated with both the outside steam cooler and back pressure extraction steam turbine.The system performance models are built by the Ebsilon Professional software.The performances of optimized systems are analyzed by the unit consumption method.The off-design performances of optimization systems are analyzed.The results show that:the standard power generation coal consumption rates of optimization systems 1 and 2 are decreased by 1.88 g·(kW·h)^(–1),2.97 g·(kW·h)^(–1)compared with that of the 700°C reference system;the average superheat degrees of regenerative steam extractions of optimized systems 1 and 2 are decreased by 122.2°C,140.7°C(100%turbine heat acceptance condition),respectively.The comparison results also show that the performance of the optimized system 2 is better than those of the optimized system 1 and the 700°C reference system.The power generation standard coal consumption rate and the power generation efficiency of the optimized system 2 are about 232.08 g·(kW·h)^(–1)and 52.96%(100%turbine heat acceptance condition),respectively.展开更多
基金National Natural Science Foundation of China(No.60974119)
文摘Ultra-supercritical(USC) unit is more and more popular in coal-fired power industry.In this paper,closed-loop identification based on subspace model identification(SMI) is introduced for superheated steam temperature system of USC unit.Closed-loop SMI is applied to building step response model of the unit directly.The parameters selection method is proposed to deal with the parameter sensitivity and improve the reliability of the model.Finally,the model is used in model identification of real USC unit.
基金the Shandong Electric Power Engineering Consulting Institute science and technology project(Grant No.37-K2014-33).
文摘Improving the primary steam parameters is one of the most direct ways to improve the cycle efficiency of a powergeneration system. In the present study, the typical problem connected to the excessively high superheat degree ofextraction steam in an ultra-supercritical (USC) double-reheat unit is considered. Using a 1000 MW power plantas an example, two systems (case 1 and case 2) are proposed, both working in combination with a regenerativesteam turbine. The thermal performances of these two systems are compared with that of the original systemthrough a heat balance method and an exergy balance strategy. The results reveal that the two coupled systemscan significantly reduce the superheat degree of extraction steam, turbine heat rate, and coal consumption of theunit and improve the energy utilization efficiency. These results will provide useful theoretical guidance to futureinvestigators wishing to address the general problem relating to energy conservation and modelling of the coupledextraction steam regenerative system of USC double-reheat units.
基金the National Nature Science Foundation of China(No.60974119)the Subject Construction of Shanghai University of Engineering Science(No.2018xk-B-09)the Young Teacher Training Scheme of Shanghai Universities(No.ZZGCD15007)
文摘Ultra-supercritical(USC) coal-fired unit is more and more popular in these years for its advantages.But the control of USC unit is a difficult issue for its characteristic of nonlinearity, large dead time and coupling among inputs and outputs. In this paper, model predictive control(MPC) method based on multi-model and double layered optimization is introduced for coordinated control of USC unit running in sliding pressure mode and fixed pressure mode. Three inputs(i.e. valve opening, coal flow and feedwater flow) are employed to control three outputs(i.e. output power, main steam temperature and main steam pressure). The step responses for the dynamic matrix control(DMC) are constructed using the three inputs by the three outputs under both pressure control mode. Piecewise models are built at selected operation points. In simulation, the output power follows load demand quickly and main steam temperature can be controlled around the setpoint closely in load tracking control. The simulation results show the effectiveness of the proposed methods.
基金financially supported by National key research and development program of China(No.2017YFB0602101,2018YFB0604404)。
文摘700°C double reheat advanced ultra-supercritical power generation technology is one of the most important development directions for the efficient and clean utilization of coal.To solve the great exergy loss problem caused by the high superheat degrees of regenerative steam extractions in 700°C double reheat advanced ultra-supercritical power generation system,two optimization systems are proposed in this paper.System 1 is integrated with the back pressure extraction steam turbine,and system 2 is simultaneously integrated with both the outside steam cooler and back pressure extraction steam turbine.The system performance models are built by the Ebsilon Professional software.The performances of optimized systems are analyzed by the unit consumption method.The off-design performances of optimization systems are analyzed.The results show that:the standard power generation coal consumption rates of optimization systems 1 and 2 are decreased by 1.88 g·(kW·h)^(–1),2.97 g·(kW·h)^(–1)compared with that of the 700°C reference system;the average superheat degrees of regenerative steam extractions of optimized systems 1 and 2 are decreased by 122.2°C,140.7°C(100%turbine heat acceptance condition),respectively.The comparison results also show that the performance of the optimized system 2 is better than those of the optimized system 1 and the 700°C reference system.The power generation standard coal consumption rate and the power generation efficiency of the optimized system 2 are about 232.08 g·(kW·h)^(–1)and 52.96%(100%turbine heat acceptance condition),respectively.
