With the continuous progress of the work of "carbon neutrality and carbon peak", the installed scale of photovoltaic, wind power and other new energy is expanding, energy saving and consumption reduction as well as flexibility improvement become the two key tasks the thermal power units faced. Through mathematical modeling and hourly calculation analysis for the hybrid system, performance and economic characters for solar-thermal systems replacing high pressure heaters are obtained. The calculation results indicate that, using solar thermal and coal fired hybrid system can realize sharp decline of the unit coal consumption, which is a most direct and effective method for coal saving and reducing consumption, it has great significance for life prolonging of the units to be retired from active service because of high coal consumption indexes. However, the economic benefit of the system itself is insufficient. So it can be supplemented with molten salt electric heater to improve the system's frequency modulation ability and enhance the project's profitability. According to the calculation, when the frequency modulation income is not considered, the system's yield is only 6.0%, but it can be increased to 8.0% after considering the frequency modulation income. Therefore, the hybrid system has double effects in improvement of both coal saving transformation and flexibility transformation.

solar photothermal  /  coal-fired power generation  /  frequency modulation  /  peak shaving  /  economy