Performance Study Of A Solar Aided Coal-fired Power Plant(SACPP) With Thermal Energy Storage System

China is a big country depending greatly on traditional energy especially coal and a lot of pollution are produced during the power production process in coal-fired power plant which endangers the national physical and mental health.The space for energy saving and emission reduction has been smaller by increasing the parameters and increasing the efficiency of the unit,so it is necessary to use alternative energy to achieve sustainable development.It is an effective usage for solar power and a good way to save coals in power plant that integrates solar power into traditional coal-fired power station.Considering the instability of solar power,an thermal energy storage(TES)system is needed which is the security for a steady integrated system.The model researched in this paper is a 660MW power station integrated with a solar power tower plants and uses two-tank molten salt storage system that all the energy from collector field enter the system firstly before working in different heat exchanger.The thermal energy storage(TES)system which can store energy and release energy simultaneously works as a buffer that make the output totally steady.A new operation mode is also proposed that the boiler in 75%THA condition cooperating with the output of solar side works with the turbine in 80%-90%THA condition.This study is conducted in two cases,the Case 1 of units following solar energy side and the Case 2 of solar energy side following units,and a computer simulation model is also established to analyse the whole-month performance of TES system and its impact on integrated system in each season.The control strategies fitting different seasons for TES system are also worked out and the aperture area of heliostats and the capacity of thermal storage are optimized.The conclusion is that The solar-to-electricity efficiency of the integration system with the TES is 26.42-26.89%and the reduced coal consumption rate of the integration system is 5.78%-15.55%referring to 80%-90%THA condition.The TES system can extend the total running time(increase about 75%in spring and summer and 40%in autumn and winter)and keep the solar energy side output completely steady.The LCOE(levelized cost of electricity)of the solar energy side of the integration system is 0.0513 $/kWh in Case 1 and 0.0572 $/kWh in Case 2 and Case 1 is the better mode of operation.