Performance Study And Optimization On The Solar Aided Coal-fired Power Unit

China as a big traditional energy country,coal-fired power plants provide nearly 70% of the electricity,but also cause a lot of pollution and emissions.Therefore,there is an urgent need for energy conservation and emission reduction in China.We need to find clean energy to reduce the use of traditional energy and solar energy is a very suitable ideal clean energy for this situation.But independent solar power plants have some shortcomings,such as low efficiency and large area.This paper combines solar energy as mixed energy with traditional coal-fired power plants,uses solar high-pressure feed water heater H0 and secondary reheating system to generate electricity in cooperation with coal-fired units respectively,and proposes solar-aided coal-fired power plant and solar double-reheated hybrided with coal-fired power plants system.Based on MATLAB/Simulink,the whole operating mode model of the system is established and simulated.Solar-aided coal-fired power plant system uses solar energy to heat feed-water through high-pressure H0,so as to increase the temperature of boiler inlet feed water.In this paper,the maximum solar energy input for the safe operation of the system is determined based on all-condition simulation,and the thermal economy of the cooperative system is evaluated.The case of a 600 MW ultra supercritical unit in Zhuhai shows that the boiler efficiency and solar photoelectric efficiency decrease with the increase of solar energy input.When the input of solar energy increases from 16663 kW to 66544 kW(100% THA),the photoelectric efficiency of solar energy decreases from 23.33% to 20.33%.The solar-aided coal-fired power plant has higher photoelectric efficiency at high load,and higher coal-saving rate at low load.Solar double-reheated hybrided with coal-fired power plants system uses solar energy to reheat the exhaust steam at the outlet of the middle pressure cylinder,so that the inlet steam into the low pressure cylinder can achieve temperature rise,reduce the moisture loss of the low pressure cylinder and improve the thermal economy of the system.In this paper,the maximum solar energy input for the safe operation of the cooperative scheme is determined based on full-condition simulation.At the same time,the thermal economy evaluation index of the solar coal-to-light ratio is proposed,which can better evaluate the actual solar energy conversion rate.The case of a 600 MW ultra-supercritical unit in Zhuhai shows that when the input energy of solar energy is 24592 kW,the ratio of solar energy to coal power increases to 0.0629 at 100% THA and 0.0731 at 40% THA.With the increase of solar energy input,the efficiency of steam turbine and solar photoelectric efficiency increase.The solar photoelectric efficiency of the cooperative power station with solar secondary reheating is over 28%,and the solar photoelectric efficiency increases with the increase of the input solar energy.When solar energy input increases from 0 kW to 24592 kW,the photoelectric efficiency of solar energy increases from 28.91% to 29.65% under 100% THA condition,which proves that the solar secondary reheat cooperative coal-fired power station is one of the best ways of thermal economy at present.