Research On Dynamic Performance And Operation Strategy Of Integrated Solar Combined Cycle Power Generation System

Integrated solar combined cycle(ISCC)system is an efficient and clean power generation technology,which can not only decrease the fuel consumption and CO2 emission compared with the combined cycle plant,but also has the less investment than solar thermal power plant.In this paper,the trough solar field complementary combined cycle system is selected as the research object,the operation strategies of the ISCC system under different operation conditions are presented,and the transient performance of the ISCC system is studied.Three kinds of trough solar field ISCC systems are introduced,which use the heat transfer oil(HTO),water/steam,gas as the heat transfer fluid in the solar field,respectively.The thermal performances are discussed and compared among three kinds of ISCC systems.The differences in thermal performances of the three systems are obtained through the simulations of typical daily and annual operating conditions.After that,the economic performances are compared among the three ISCC systems.At last,due to the problems of operation in the actual power plant,the ISCC system with HTO as the working medium in the solar field is selected as the case study in the following research.The dynamic modeling of the main equipment in the ISCC system is built based on the STAR-90 software platform,such as solar collector,oil-water heat exchanger and superheater.After that,according to the working process of the ISCC system,each device is connected in sequence,and modeling of the whole ISCC system is finished,the dynamic simulation of different operating conditions can be conducted.To improve the economic performance,some parameters of ISCC system need to be optimized.The HTO velocity in the collectors is optimized by putting forward the concept of solar field conversion efficiency,the thermal efficiency of solar field and the energy consumption of HTO pump are taken into account,then the optimal velocities of the HTO in the collectors under different DNIs are obtained finally.Besides,based on the maximum net profit of the solar field,the starting and stopping times of the solar field are also optimized.After that,the processes of startup and stop of the solar field are simulated.Based on the dynamic model and parameter optimization above,aiming to two ISCC systems(with/without the thermal storage system),different operation strategies are proposed.The dynamic performances of the two ISCC systems are compared under the whole day operation condition.The results show that both of these two systems can operate safety,while,the operational stability of the ISCC system with thermal storage system is better than the other one obviously.Besides,the operation parameters,include the main steam and reheat parameters,the output power of the ISCC system with thermal storage system has no fluctuations when it operates.The effects of DNI fluctuation on the stability of ISCC system is reduced.In order to verify the universality of the operation strategy of the ISCC system with thermal storage system,the simulation is conducted under different operation conditions.The results show that the ISCC system can operate safely and stably no matter whether the solar radiation is weak or strong.It shows that the operation strategy has a good match with the system.In addition,the transient performance of the system is simulated when the temperature and the DNI vary concurrently,and the dynamic responses of the system parameters with the variations of the weather are explored under the operation strategy.Due to the problems of operation safety,the solar energy capacity integrated into the combined cycle is limited.To improve the output power proportion of renewable energy,a new Multi-energy complementary power generation(MECPG)system based on ISCC system is proposed,which has ISCC subsystem,photovoltaic subsystem,and wind subsystem.The operation strategy and transient performance of the new system are discussed.The results show that,the new system has good security and stability during the operation,and all the wind and solar energy can be used,there are no curtailments of wind and light.With the same operating condition(typical daily operating condition),the proportion of renewable energy power generation in the new system is 2.3%higher than that of the ISCC system.At last,the economic performance of the new system is analyzed,the LCOE of the new system is 0.0512$/kWh,a little better than the ISCC system.